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Sample records for arid alluvial basins

  1. Spatio-temporal recharge patterns in a semi-arid alluvial basin with irrigated crops

    NASA Astrophysics Data System (ADS)

    Ruud, N. C.; Harter, T.; Naugle, A. W.

    2001-12-01

    Recharge in semi-arid regions with irrigated crops is predominantly driven by irrigation technology and cropping patterns, but also by the seasonal distribution of rainfall and the availability of irrigation water. A significant amount of basin recharge occurs from ephemeral streams and unlined irrigation canals. A spatially distributed, GIS-based hydrologic model of water application and water use at the land-atmosphere interface was developed to estimate transient recharge to the deep vadose zone and into the unconfined alluvial aquifer. The spatial basis for the hydrologic model are individual landuse units (diffuse recharge) and a network of streams and canals with water seepage (lineal recharge). The land-atmosphere interface and unsaturated zone model component (LAIUZ) is coupled to a surface water supply model component (SWSM) that provides surface water deliveries by district or sub-district, depending on available information. Using LAIUZ and SWSM, we investigate the regional behavior and spatio-temporal variability of deep vadose zone recharge in the 3,800 square kilometer Tule groundwater basin of the San Joaquin Valley, California. Surface water management in the topographically flat basin is divided between two dozen irrigation and water districts. All surface water is imported or is natural discharge into the basin. Groundwater extractions are managed by landowners on a field-by-field basis. Monthly varying recharge and groundwater pumping rates are computed for the hydrologic years 1970 through 2000. The average size of the GIS landuse units is 0.4 sq. kilometers. The GIS coverage distinguishes over 60 landuse types. Applied and consumptive water use are computed based on actual evapotranspiration and known irrigation or water use efficiencies for each landuse unit. Seepage from streams is computed by mass balance. The resulting model estimates of groundwater recharge and pumping are in good agreement with measured groundwater level changes for the thirty-year period (model validation). Throughout the region, the deep vadose zone (up to 30 m deep) is found to account for a significant amount of intermediate-term basin storage, particularly during wet year cycles. The hydrologic model demonstrates that practically all of the annual precipitation (230 mm) is available for intermediate storage in the root zone, crop water uptake, or deep percolation. No direct losses to evaporation occur, presumably because most precipitation occurs during the winter months. Diffuse recharge is 110 mm/year (range: 38 - 200 mm/year). Lineal recharge accounts for one-third of the total recharge (170 mm/year) in the basin. In wet years, lineal recharge along streams and in intentional recharge basins may account for over 50% of the total recharge, whereas in dry years it may be as little as 8%.

  2. Impacts of Urbanization on Groundwater Quality and Recharge in a Semi-arid Alluvial Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The management of groundwater resources is paramount in semi-arid regions experiencing urban development. In the southwestern United States, enhancing recharge of urban storm runoff has been identified as a strategy for augmenting groundwater resources. An understanding of how urbanization may impac...

  3. Characterizing arid region alluvial fan surface roughness with airborne laser swath mapping digital topographic data

    NASA Astrophysics Data System (ADS)

    Frankel, Kurt L.; Dolan, James F.

    2007-06-01

    Range-front alluvial fan deposition in arid environments is episodic and results in multiple fan surfaces and ages. These distinct landforms are often defined by descriptions of their surface morphology, desert varnish accumulation, clast rubification, desert pavement formation, soil development, and stratigraphy. Although quantifying surface roughness differences between alluvial fan units has proven to be difficult in the past, high-resolution airborne laser swath mapping (ALSM) digital topographic data are now providing researchers with an opportunity to study topography in unprecedented detail. Here we use ALSM data to calculate surface roughness on two alluvial fans in northern Death Valley, California. We define surface roughness as the standard deviation of slope in a 5-m by 5-m moving window. Comparison of surface roughness values between mapped fan surfaces shows that each unit is statistically unique at the 99% confidence level. Furthermore, there is an obvious smoothing trend from the presently active channel to a deposit with cosmogenic 10Be and 36Cl surface exposure ages of ˜70 ka. Beyond 70 ka, alluvial landforms become progressively rougher with age. These data suggest that alluvial fans in arid regions smooth out with time until a threshold is crossed where roughness increases at greater wavelength with age as a result of surface runoff and headward tributary incision into the oldest surfaces.

  4. Estimating the surface age of arid-zone alluvial fans using spaceborne radar data

    NASA Astrophysics Data System (ADS)

    Hetz, Guy; Mushkin, Amit; Blumberg, Dan G.; Baer, Gidi

    2013-10-01

    Alluvial fans constitute important recorders of tectonic and climatic signals. Thus, determining the age of alluvial deposits is a common and pivotal component in many quantitative studies of recent tectonic activity, past climatic variations and landscape evolution processes. In this study we build on the established relation between surface age and surface roughness and examine the use of radar backscatter data as a calibrated proxy for constraining the age of alluvial surfaces in such environments. This study was conducted in the hyper-arid environment of the southern Arava rift valley north of the Gulf of Aqaba. ALOS-PALSAR L-Band dual-polarized (i.e., HH, HV) data with different incidence angles (24°, 38°) and resolutions (6.25m, 12.5m) were examined for 11 alluvial surfaces, for which surface ages ranging from 5-160 ka were previously determined. As expected, radar backscatter in such low-relief hyper-arid desert environments responded primarily to SR at pixel-scales and below. Nonetheless, measured backscatter values for single pixels were found to be unsuitable proxies for surface age because of the natural variability in SR across alluvial units of a given age. Instead, we found the statistical properties of radar pixel populations within a given unit to be the most effective proxies for surface age. Our results show that the mean backscatter value within representativeROI's (region of interest) provided the best predictor for surface age: Lower mean backscatter values correlated well with older and smoother alluvial surfaces. The HHpolarized image with ~38° incidence angle and 6.25 m/pixel resolution allowed the best separation of surface ages. This radar-based approach allows us to quantitatively constrain the age of alluvial surfaces in the studied region at comparable uncertainty to that of "conventional" surface dating techniques commonly used.

  5. Chemical and Physical Weathering in a Hot-arid, Tectonically Active Alluvial System (Anza-Borrego Desert, CA)

    NASA Astrophysics Data System (ADS)

    Joo, Y. J.; Elwood Madden, M.; Soreghan, G. S.

    2014-12-01

    Climate and tectonics are primary controls on bedrock erosion, and sediment production, transport, and deposition. Additionally, silicate weathering in tectonically active regions is known to play a significant role in global climate owing to the high rates of physical erosion and exposure of unweathered bedrock to chemical weathering, which removes CO2 from the atmosphere. Therefore, the feedback between weathering and climate is key to understanding climate change through Earth history. This study investigates chemical and physical weathering of alluvial sediments in the Anza-Borrego Desert, California, located in the southern part of the San Andreas Fault System. This setting provides an ideal opportunity to study weathering in a hot and arid climate with mean annual temperatures of ~23 °C and mean annual precipitation of ~160 mm in the basin. Samples were collected along a proximal-to-distal transect of an alluvial-fan system sourced exclusively from Cretaceous tonalite of the Peninsular Range. The single bedrock lithology enables exploration of the effects of other variables — climate, transport distance, drainage area, and tectonics— on the physical and chemical properties of the sediments. Although minimal overall (CIA = 56-61), the degree of chemical weathering increases down transect, dominated by plagioclase dissolution. BET surface area of the mud (<63µm) fraction decreases distally, which is consistent with coarsening grain-size. Chemical alteration and BET surface area both increase in a distal region, within the active Elsinore Fault zone. Extensive fracturing here, together with a more-humid Pleistocene climate likely facilitated in-situ bedrock weathering; specifically, dissolution of primary minerals (e.g. plagioclase), preceding the arid alluvial erosion, transport, and deposition in the Holocene. This study further seeks to disentangle the complex record of the climate and tectonic signals imprinted in these sediments.

  6. Alluvial plain dynamics in the southern Amazonian foreland basin

    NASA Astrophysics Data System (ADS)

    Lombardo, U.

    2015-10-01

    Alluvial plains are formed with sediments that rivers deposit on the adjacent flood-basin, mainly through crevasse splays and avulsions. These result from a combination of processes, some of which push the river towards the crevasse threshold, while others act as triggers. Based on the floodplain sedimentation patterns of large rivers in the southern Amazonian foreland basin, it has been suggested that alluvial plain sediment accumulation is primarily the result of river crevasse splays triggered by above normal precipitation events due to La Niña. However, more than 90 % of the Amazonian river network is made of small rivers and it is unknown whether small river floodplain sedimentation is influenced by the ENSO cycle as well. Using Landsat images from 1984 to 2014, here I analyse the behaviour of all the twelve tributaries of the Río Mamoré with a catchment in the Andes. I show that these are very active rivers and that the frequency of crevasses is not linked to ENSO activity. I found that most of the sediments eroded from the Andes by the tributaries of the Mamoré are deposited in the alluvial plains, before reaching the parent river. The mid- to late Holocene paleo-channels of these rivers are located tens of kilometres further away from the Andes than the modern crevasses. I conclude that the frequency of crevasses is controlled by intrabasinal processes that act on a year to decade time scale, while the average location of the crevasses is controlled by climatic or neo-tectonic events that act on a millennial scale. Finally, I discuss the implications of river dynamics on rural livelihoods and biodiversity in the Llanos de Moxos, a seasonally flooded savannah covering most of the southern Amazonian foreland basin and the world's largest RAMSAR site.

  7. Issues associated with the distinction between climatic and tectonic controls on Permian alluvial fan deposits from the Kotzen and Barnim Basins (North German Basin)

    NASA Astrophysics Data System (ADS)

    Kallmeier, Enrico; Breitkreuz, Christoph; Kiersnowski, Hubert; Geißler, Marion

    2010-01-01

    Facies analysis focussing on coarse-grained sediments has been carried out on more than 2500 m of drill cores from seven wells from southern margins of the North German Basin (NGB). The NGB forms a central element of the Southern Permian Basin (SPB). The wells exposed conglomerates and sandstones of the Rotliegend Grüneberg and Parchim Formations deposited in the Kotzen Basin and the Barnim Basin. 17 lithofacies types have been grouped into six lithofacies associations. The studied successions are dominated by fluid gravity flow deposits (hyperconcentrated flows and stream flows) of alluvial fan and alluvial plain systems. Maximum particle size/bed thickness plots (MPS/BTh) support the interpretation as fluid gravity flow deposits. The MPS and BTh data have also been used to differentiate coarsening-thickening and fining-thinning trends of the fan systems. The dominance of water-rich mass flow processes together with sedimentary structures such as dewatering structures and outwashed tops suggests the presence of wet-type fans and plains under semi-humid to semi-arid seasonal climates in the central SPB. The investigated sediments show variation in clast composition subsequent to deep erosion processes on basin margins and changes of source areas. Synsedimentary normal faults and clastic dykes have been interpreted as indicators of tectonic activity of grabens itself and its frames. On a larger scale, then evolution from a half-graben to a graben is apparent for the Tuchen Sub-basin at least. The progradational/retrogradational cycles of the studied alluvial fan systems document combined local tectonic movements and influences of climatic changes. However, our data did not allow for a clear distinction between climatic and tectonic signals. Furthermore, a one-to-one correlation of fan cycles with depositional trends in the NGB basin centre would appear to be oversimplistic.

  8. 10Be in Quartz Gravel from the Gobi Desert and Evolutionary History of Alluvial Sedimentation in the Ejina Basin, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Lyu, Y.

    2014-12-01

    Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate. However, such work is limited by a lack of suitable dating material preserved in the Gobi Desert, but cosmogenic 10Be has great potential to date the Gobi deserts. In the present study, 10Be in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages. Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago, whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka. The latter developed gradually northward and eastward to modern terminal lakes of the river. These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin. Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin. Intense floods and large water volumes would mainly occur during the short deglacial periods.

  9. Water availability and use pilot; methods development for a regional assessment of groundwater availability, southwest alluvial basins, Arizona

    USGS Publications Warehouse

    Tillman, Fred D; Cordova, Jeffrey T.; Leake, Stanley A.; Thomas, Blakemore E.; Callegary, James B.

    2011-01-01

    Executive Summary: Arizona is located in an arid to semiarid region in the southwestern United States and is one of the fastest growing States in the country. Population in Arizona surpassed 6.5 million people in 2008, an increase of 140 percent since 1980, when the last regional U.S. Geological Survey (USGS) groundwater study was done as part of the Regional Aquifer System Analysis (RASA) program. The alluvial basins of Arizona are part of the Basin and Range Physiographic Province and cover more than 73,000 mi2, 65 percent of the State's total land area. More than 85 percent of the State's population resides within this area, accounting for more than 95 percent of the State's groundwater use. Groundwater supplies in the area are expected to undergo further stress as an increasing population vies with the State's important agricultural sector for access to these limited resources. To provide updated information to stakeholders addressing issues surrounding limited groundwater supplies and projected increases in groundwater use, the USGS Groundwater Resources Program instituted the Southwest Alluvial Basins Groundwater Availability and Use Pilot Program to evaluate the availability of groundwater resources in the alluvial basins of Arizona. The principal products of this evaluation of groundwater resources are updated groundwater budget information for the study area and a proof-of-concept groundwater-flow model incorporating several interconnected groundwater basins. This effort builds on previous research on the assessment and mapping of groundwater conditions in the alluvial basins of Arizona, also supported by the USGS Groundwater Resources Program. Regional Groundwater Budget: The Southwest Alluvial Basins-Regional Aquifer System Analysis (SWAB-RASA) study produced semiquantitative groundwater budgets for each of the alluvial basins in the SWAB-RASA study area. The pilot program documented in this report developed new quantitative estimates of groundwater budget components using recent (2000-2007) data and methods of data analysis. Estimates of inflow components, including mountain-front recharge, incidental recharge from irrigation of agriculture, managed recharge from recharge facilities, interbasin underflow from upgradient basins, and streamflow losses, are quantified for recent time periods. Mountain-front recharge is the greatest inflow component to the groundwater system and was estimated using two methods: a basin characteristic model and new precipitation information used in a previously developed regression equation. Annual mountain-front recharge for the study area for 1940-2007 estimated by the two methods is 730,000 acre-ft for the basin characteristic model and 643,000 acre-ft for the regression equation, representing 1.5 percent and 1.3 percent of precipitation, respectively. Outflow components, including groundwater withdrawals, evapotranspiration, and interbasin flow to downgradient basins, are also presented for recent time periods. Groundwater withdrawals accounted for the largest share of the water budget, with nearly 2.4 million acre-ft per year withdrawn from the study area in recent years. Evapotranspiration from groundwater was estimated at nearly 1.3 million acre-ft per year for the study area using a newly developed method incorporating vegetation indices from satellite images and land cover information. For water-budget components with temporal variation that could be assessed from available data, estimates for intervening time periods since before development were also developed. An estimate of aquifer storage change, representing both gains to and losses from the groundwater system since before development, was derived for the most developed basins in the study area using available estimates of groundwater-level changes and storage coefficients. An overall storage loss of 74.5 million acre-ft was estimated for these basins within the study area. Demonstration

  10. IBIEM modelling of the amplification of seismic waves by a three-dimensional layered alluvial basin

    NASA Astrophysics Data System (ADS)

    Liu, Zhongxian; Liang, Jianwen; Huang, Yihe; Liu, Lei

    2016-02-01

    We develop an indirect boundary integral equation method (IBIEM) to solve the scattering of seismic waves by a 3-D layered alluvial basin. We adopt the dynamic Green's functions for concentrated loads for a layered half-space derived from the modified stiffness method. This new algorithm of Green's function can solve the near-source response efficiently and accurately, and also facilitates the meshless implementation of the IBIEM. The numerical accuracy and stability of the IBIEM are tested for a homogeneous, hemispherical alluvial basin, and a two-layered model. Based on the IBIEM, the effects of several important parameters, such as the incident frequency, the angle of incidence and the properties of the alluvial layers are investigated for incident plane P and SV waves, respectively. The results show that the local amplification effects of a 3-D layered alluvial basin on the ground motion are strikingly significant, and that the spatial variation of the displacement response is drastic. We also find that the thickness of the near-surface low-velocity alluvial layer has a pronounced influence on the frequency spectrum of ground motion within the basin. As for the thick low-velocity layer, the amplification effect on the displacement amplitude spectrum appears in a wide range of frequencies, with more resonant models in the same frequency range. As for the thin low-velocity layer, in contrast, the amplification effect is close to the homogeneous case but becomes more significant for high-frequency waves. The displacement amplification for a basin with a soft intermediate layer is larger than that of the homogeneous basin for the lower frequencies, but seems to be weakened for high-frequency waves. Additionally, the damping ratio of the alluvial layer can substantially reduce the displacement amplitude in the basin, especially in the range of resonant frequencies. Our results provide a better understanding of the 3-D wave focusing and basin-edge effect within 3-D layered alluvial basins.

  11. Late Quaternary landscape evolution in the Kunlun Mountains and Qaidam Basin, Northern Tibet: A framework for examining the links between glaciation, lake level changes and alluvial fan formation

    USGS Publications Warehouse

    Owen, L.A.; Finkel, R.C.; Haizhou, M.; Barnard, P.L.

    2006-01-01

    The Qaidam Basin in Northern Tibet is one of the largest hyper-arid intermontane basins on Earth. Alluvial fans, pediment surfaces, shorelines and a thick succession of sediments within the basin, coupled with moraines and associated landforms in the adjacent high mountain catchments of the Kunlun Mountains, record a complex history of Late Quaternary paleoenvironmental change and landscape evolution. The region provides an ideal natural laboratory to examine the interaction between tectonics and climate within a continent-continent collision zone, and to quantify rates of landscape evolution as controlled by climate and the associated glacial and hydrological changes in hyper-arid and adjacent high-altitude environments. Geomorphic mapping, analysis of landforms and sediments, and terrestrial cosmogenic radionuclide surface exposure and optically stimulated luminescence dating serve to define the timing of formation of Late Quaternary landforms along the southern and northwestern margins of the Qaidam Basin, and in the Burhan Budai Shan of the Kunlun Mountains adjacent to the basin on the south. These dates provide a framework that suggests links between climatic amelioration, deglaciation, lake desiccation and alluvial fan evolution. At least three glacial advances are defined in the Burham Budai Shan of the Kunlun Mountains. On the northern side of this range these occurred in the penultimate glacial cycle or early in the last glacial cycle, during the Last Glacial Maximum (LGM)/Lateglacial and during the Holocene. On the south side of the range, advances occurred during the penultimate glacial cycle, MIS-3, and possibly the LGM, Lateglacial or Holocene. Several distinct phases of alluvial fan sedimentation are likewise defined. Alluvial fans formed on the southern side of the Kunlun Mountains prior to 200 ka. Ice-contact alluvial fans formed during the penultimate glacial and during MIS-3. Extensive incised alluvial fans that form the main valley fills north of the Burham Budai and extend into the Qaidam Basin are dated to ???30 ka. These ages suggest that there was a period of alluvial fan aggradation and valley filling that persisted until desiccation of the large lakes in the Qaidam Basin post ???30 ka led to base level lowering and active incision of streams into the valley fills. The continued Lateglacial and Holocene desiccation likely led to further degradation of the valley fills. Ice wedge casts in the Qaidam Basin date to ???15 ka, indicating significant Lateglacial climatic amelioration, while Holocene loess deposits north of the Burham Bdudai suggest that aridity has increased in the region since the early Holocene. From these observations, we infer that the major landscape changes within high glaciated mountains and their adjacent hyper-arid intermontane basins, such as the Kunlun Mountains and Qaidam Basin, occur rapidly over millennial timescales during periods of climatic instability. ?? 2006 Elsevier Ltd and INQUA.

  12. Variation in sedimentology and architecture of Eocene alluvial strata, Wind River and Washakie basins, Wyoming

    SciTech Connect

    Patterson, P.E.; Larson, E.E. )

    1991-03-01

    Eocene continental, alluvial strata of the Wind River Formation (Wind River Basin) and the Cathedral Bluffs Member of the Wasatch Formation (Washakie basin) provide two examples of Laramide intermontane basin aggradation. These alluvial sediments primarily represent overbank flood deposits marginal to channel complexes. Their sedimentology and architecture, although grossly similar, appear to vary somewhat with proximity to Laramide uplifts. In both cases, repetitive sedimentation on the floodplain produced a succession of depositional couplets, each composed of a light-gray sand overlain by a red clay-rich silt or sand. The lower sands are tabular bodies that, near their distal margins, taper discernibly. They commonly display planar and ripple-drift laminations. Upper clay-rich layers, which are laminated, are also generally tabular. Those floodplain strata depositional proximal to Laramide uplifts show little evidence of scouring prior to deposition of the next, overlying couplet. Most of these sedimentary layers, therefore, are laterally continuous (up to 2 km). This alluvial architecture results in relatively uniform porosity laterally within depositional units but variable porosity stratigraphically through the sequence. In contrast, alluvial sediments deposited farther from the Laramide uplifts have undergone sporadic incision (either during rising flood stage or subsequently) followed by aggradation. As a result, many of these floodplain couplets are discontinuous laterally and, hence, exhibit large-scale lateral variability in porosity. Both alluvial sequences have undergone similar types and extents of burial diagenesis.

  13. Orbital forcing in the early Miocene alluvial sediments of the western Ebro Basin, Northeast Spain

    NASA Astrophysics Data System (ADS)

    Garces, M.; Larrasoaña, J. C.; Muñoz, A.; Margalef, O.; Murelaga, X.

    2009-04-01

    Paleoclimatic reconstructions from terrestrial records are crucial to assess the regional variability of past climates. Despite the apparent direct connection between continental sedimentary environments and climate, interpreting the climatic signature in ancient non-marine sedimentary sequences is often overprinted by source-area related signals. In this regard, foreland basins appear as non-ideal targets as tectonically-driven subsidence and uplift play a major control on the distribution and evolution of sedimentary environments and facies. Foreland basins, however, often yield among the thickest and most continuous stratigraphic records available on continents. The Ebro Basin (north-eastern Spain) is of particular interest among the circum-mediterranean alpine foreland basins because it evolved into a land-locked closed basin since the late Eocene, leading to the accumulation of an exceptionally thick (>5500 m) and continuous sequence of alluvial-lacustrine sediments over a period of about 25 Myr. In this paper we present a detailed cyclostratigraphic study of a 115 m thick section in the Bardenas Reales de Navarra region (western Ebro Basin) in order to test orbital forcing in the Milankovitch frequency band. The study section corresponds to the distal alluvial-playa mud flats which developed in the central sector of the western Ebro Basin, with sediments sourced from both the Pyrenean and Iberian Ranges. Sediments consist of brown-red alluvial clay packages containing minor fine-grained laminated sandstones sheet-beds and channels, grey marls and thin bedded lacustrine limestones arranged in 10 to 20 m thick fining-upwards sequences. Red clayed intervals contain abundant nodular gypsum interpreted as representing a phase of arid and low lake level conditions, while grey marls and limestones indicate wetter intervals recording the expansion of the inner shallow lakes. A magnetostratigraphy-based chronology indicates that the Peñarroya section represents a time interval of about 500 kyr centered around chron C6r, although inferred absolute ages diverge depending on the assumed calibration of geomagnetic reversals with the astronomical time scale (Billups et al., 2004, Lourens et al., 2004). The section was sampled with a portable drill at regular intervals of about 30 cms, representing a time resolution of near 1 kyr. Spectral analysis of different measured parameters (lithology code, color, magnetic susceptibility and other rock magnetic parameters) revealed significant power at 20.4 m, 9.6 m and 4.2 m, which correspond to a ratio of 1:2.1:4.9 similar to that given by the Milankovitch cycles of eccentricity, obliquity and precession. Maximum power in the spetrum is focused in the eccentricity and obliquity bands while signal corresponding to precession is weakly expressed. The existing uncertainties in the astronomical tuning of the Early Miocene geomagnetic polarity time scale prevents us from using magnetostratigraphy to anchor the Peñarroya record with the astronomical solutions (Laskar et al., 2004). Instead, we have tried the expression of the eccentricity cycle to tune the Peñarroya section. We correlated the thick red clayed (dry phase) intervals with eccentricity minima, a phase relationship which is in agreement with that derived from earlier studies in marine and continental records from the Miocene of the Iberian plate (Abels et al., 2008, Sierro et al., 2000). The resulting tuning of the Peñarroya section yields an age for the base of geomagnetic chron C6r which fits with earlier work of Billups et al., (2004), while the top of C6r gives a significantly younger age. References Abels, H., Abdul Aziz, A., Calvo, J.P. and Tuenter, E., 2008. Shallow lacustrine carbonate microfacies document orbitally paced lake-level history in the Miocene Teruel Basin (North-East Spain), Sedimentology doi: 10.1111/j.1365-3091.2008.00976.x. Billups, K., Pälike, H., Channell, J.E.T., Zachos, J. and Shackleton, N.J., 2004. Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time sca

  14. Depositional facies and Hohokam settlement patterns of Holocene alluvial fans, N. Tucson Basin, Arizona

    SciTech Connect

    Field, J.J.

    1985-01-01

    The distribution of depositional facies on eight Holocene alluvial fans of varying dimensions is used to evaluate prehistoric Hohokam agricultural settlement patterns. Two facies are recognized: channel gravelly sand facies and overbank silty sand facies. No debris flow deposits occur. The channel facies is characterized by relatively well sorted stratified sands and gravels with common heavy mineral laminations. Overbank facies deposits are massive and very poorly sorted due to heavy bioturbation. Lithostratigraphic profiles from backhoe trenches and sediment size analysis document headward migration of depositional facies which results in fining upward sequences. Each sequence is a channel fan lobe with an underlying coarse grained channel sand which fines to overbank silty sands. Lateral and vertical variations in facies distributions show that depositional processes are affected by drainage basin area (fan size) and distance from fan head. Gravelly channel sands dominate at the headward portions of the fan and are more pervasive on large fans; overbank silty sands are ubiquitous at fan toes and approach closer to the fan head of smaller alluvial fans. When depositional facies are considered as records of water flow over an alluvial surface, the farming potential of each fan can be analyzed. Depositional models of alluvial fan sedimentation provide the basis for understanding Hohokam settlement patterns on active alluvial surfaces.

  15. Late Quaternary Alluvial Fans and Beach Ridge Systems in Jakes Valley, Central Great Basin, USA

    NASA Astrophysics Data System (ADS)

    Garcia, A. F.; Stokes, M.; Benitez, L.

    2002-12-01

    Alluvial fan and lake beach ridge landforms provide archives of the geomorphic response to Late Quaternary climate change within the Great Basin region. This study presents the first detailed results of landform mapping and soil characterization from Jakes Valley, a high altitude (1920m) and internally drained basin, located within a previously unstudied part of White Pine County, East-Central Nevada. Mountain front alluvial fans sourced from the White Pine and Egan Ranges (west-east basin margins) are characterized by four morphostratigraphic units: Qf0 (oldest) through to Qf3 (youngest). Analysis of the soil properties of these stratigraphic units reveals two landform-soil assemblages: 1) Qf0-1, characterized by well-developed calcic soils (stages III+ to IV) and 2) Qf2-3, characterized by less well-developed calcic soils (stages I to II). Beach ridge systems formed during pluvial lake highstands are extensively developed into the mid and distal parts of alluvial fans. Integrated field and aerial photograph mapping has revealed a sequence of between 4-6 ridges with linear and / or highly curved / arcuate morphologies. Beach ridge soil properties are characterized by less well-developed calcic soils (stages I+ to II) that are similar to soils formed in Qf2 alluvial fan units. The interaction between the alluvial fan and beach ridge landforms can be utilized to explore the geomorphic response in relation to climatic amelioration during the Late Pleistocene-Holocene transition. Of particular interest is the common occurrence of the curved / arcuate beach ridges which may correspond to a period of fan progradation coincident with base-level lowering.

  16. Estimating recharge distribution by incorporating runoff from mountainous areas in an alluvial basin in the Great Basin region of the southwestern United States.

    PubMed

    Stone, D B; Moomaw, C L; Davis, A

    2001-01-01

    A method is described to estimate the distribution of ground water recharge within hydrographic basins in the Great Basin region of the southwestern United States on the basis of estimated runoff from high mountainous areas and subsequent infiltration in alluvial fans surrounding the intermontane basins. The procedure involves a combination of Geographic Information System (GIS) analysis, empirical surface-runoff modeling, and water-balance calculations. The method addresses the need to develop and incorporate constraints on the distribution of recharge in regional-scale ground water flow modeling of arid and semiarid environments. The conceptual approach and methodology were developed for Crescent Valley, Nevada. However, the concept and method are generally applicable to any region where excess precipitation in upland areas is conveyed to lower elevations before it infiltrates to recharge the ground water system. Application of the procedure to a ground water flow model of Crescent Valley appears both qualitatively and quantitatively to result in a more accurate representation of actual recharge conditions than might otherwise have been prescribed. PMID:11708447

  17. Groundwater and Surface Water Interaction of Several Irrigation Systems in the Mississippi River Basin Alluvial Aquifer

    NASA Astrophysics Data System (ADS)

    Reba, M. L.; Rigby, J.; Czarnecki, J.; Rawlings, L.

    2013-12-01

    The Lower Mississippi River Basin alluvial aquifer provides irrigation water for agriculture in most of eastern Arkansas, western Tennessee, southeastern Missouri, western Mississippi and northeastern Louisiana. The alluvial aquifer depth to water has been declining by approximately 1 foot per year due to unsustainable pumping levels. Replacing groundwater with surface water sources in the Lower Mississippi River Basin is one of the many solutions to declining groundwater stores that has taken root in the region, especially in eastern Arkansas. Surface water irrigation systems consist of an on-farm reservoir and tailwater recovery. The reservoir is used to store water for later use during wet periods of the year and the tailwater recovery creates a closed basin of the irrigation system, allowing for use and re-use of irrigation water. Several irrigation systems were instrumented to further understand the interaction between surface water and groundwater in alluvial aquifer region. Three reservoirs, 9 streams and ditches, and 8 groundwater wells were instrumented in fall of 2011. Groundwater potentiometric surface under the storage reservoirs showed a rebound while a potentiometric surface falls sharply south and west moving away from the storage reservoirs. Preliminary results from the findings from these sites are presented.

  18. Hydrogeochemical indicators of groundwater flow systems in the Yangwu River alluvial fan, Xinzhou Basin, Shanxi, China.

    PubMed

    Han, Dongmei; Liang, Xing; Jin, Menggui; Currell, Matthew J; Han, Ying; Song, Xianfang

    2009-08-01

    Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater delta(2)H and delta(18)O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water-rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. (87)Sr/(86)Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water-rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems. PMID:19548025

  19. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada.

    SciTech Connect

    Donald S. Sweetkind; Ronald M. Drake II

    2007-01-22

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  20. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  1. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill-Hole Data in Yucca Flat, Nye County, Nevada

    USGS Publications Warehouse

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill-hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin such as alluvial fan, channel, basin axis, and playa deposits.

  2. Abo Formation alluvial facies and Associated Basin Fill, Sacramento Mountains, New Mexico

    SciTech Connect

    Speer, S.W.

    1986-03-01

    Outcrops of the Abo Formation (Wolfcampian to early Leonardian age) in the Sacramento Mountains of south-central New Mexico record the evolution of a dry alluvial fan system as it was deposited off the pedernal uplift into the Orogrande basin. The location and orientation of present-day outcrops allow us to observe an inferred east-to-west transverse facies tract consisting of: (1) proximal alluvial fans (lower Abo), which are contiguous in places with underlying Laborcita Formation fan-deltaic sediments; (2) medial anastomosed streams (middle Abo); and (3) distal low-gradient mud-dominated flood basins characterized by either distributary streams (upper Abo) or clastic tidal flats (Lee Ranch Tongue of the Abo) with associated marine carbonates (Pendejo Tongue of the Hueco Formation). Tectonism in the Pedernal highlands, which climaxed during the Late Pennsylvanian, apparently continued well into the Wolfcampian in this region, as evidenced by a major basal Abo unconformity and distinct stacked megasequences of lower Abo alluvial fan lithofacies. However, by the middle Abo, tectonic activity had quiesced and the uplift began eroding and retreating to the north and east. By the late Abo, a pediment surface had formed that was subsequently onlapped by upper Abo and eventually Yeso Formation sediments.

  3. Alluvial and bedrock aquifers of the Denver Basin; eastern Colorado's dual ground-water resource

    USGS Publications Warehouse

    Robson, Stanley G.

    1989-01-01

    Large volumes of ground water are contained in alluvial and bedrock aquifers in the semiarid Denver basin of eastern Colorado. The bedrock aquifer, for example, contains 1.2 times as much water as Lake Erie of the Great Lakes, yet it supplies only about 9 percent of the ground water used in the basin. Although this seems to indicate underutilization of this valuable water supply, this is not necessarily the case, for many factors other than the volume of water in the aquifer affect the use of the aquifer. Such factors as climatic conditions, precipitation runoff, geology and water-yielding character of the aquifers, water-level conditions, volume of recharge and discharge, legal and economic constraints, and water-quality conditions can ultimately affect the decision to use ground water. Knowledge of the function and interaction of the various parts of this hydrologic system is important to the proper management and use of the ground-water resources of the region. The semiarid climatic conditions on the Colorado plains produce flash floods of short duration and large peak-flow rates. However, snowmelt runoff from the Rocky Mountains produces the largest volumes of water and is typically of longer duration with smaller peak-flow rates. The alluvial aquifer is recharged easily from both types of runoff and readily stores and transmits the water because it consists of relatively thin deposits of gravel, sand, and clay located in the valleys of principal streams. The bedrock aquifer is recharged less easily because of its greater thickness (as much as 3,000 feet) and prevalent layers of shale which retard the downward movement of water in the formations. Although the bedrock aquifer contains more than 50 times as much water in storage as the alluvial aquifer, it does not store and transmit water as readily as the alluvial aquifer. For example, about 91 percent of the water pumped from wells is obtained from the alluvial aquifer, yet water-level declines generally have not exceeded 40 feet. By contrast, only 9 percent of the water pumped from wells is obtained from the bedrock aquifer, yet water-level declines in this aquifer have exceeded 500 feet in some areas. Depth to water in the alluvial aquifer generally is less than 40 feet, while depth to water in the bedrock aquifer may exceed 1,000 feet in some areas. Cost of pumping water to the surface and cost of maintaining existing supplies in areas of rapidly declining water levels in the bedrock aquifer affect water use. Water use is also affected by the generally poorer quality water found in the alluvial aquifer and, to a lesser extent, by the greater susceptibility of the alluvial aquifer to pollution from surface sources. Because of these factors, the alluvial aquifer is used primarily as a source of irrigation supply, which is the largest water use in the area. The bedrock aquifer is used primarily as a source of domestic or municipal supply, which is the smaller of the two principal uses, even though the bedrock aquifer contains 50 times more stored ground water than the alluvial aquifer.

  4. Distinguishing early groundwater alteration effects from pedogenesis in ancient alluvial basins: examples from the Palaeogene of southern Portugal

    NASA Astrophysics Data System (ADS)

    Pimentel, N. L.; Wright, V. P.; Azevedo, T. M.

    1996-08-01

    Colour mottling and horizons of secondary carbonates are common in ancient alluvial sequences and are normally interpreted as pedogenic features. They have been used to assess palaeoclimates, soil drainage conditions and deposition rates. Palaeogene alluvial deposits in the Sado and Lisbon basins of Portugal exhibit prominent colour variations and mottle patterns, as well as carbonate accumulations both at the bases of fining-upwards cyclothems and as thick units (up to 20 m) capping alluvial megasequences. However, these colour and carbonate features are interpreted as the products of shallow, saline, reducing groundwaters, unrelated to pedogenesis. Such non-pedogenic products are easily mistaken for soil-formed ones and criteria for differentiating the two are reviewed to assist interpretations in other alluvial deposits. Key criteria are thickness, gradational tops and bases, absence of soil horizon features, occurrence in coarser alluvium and prevalence of hydromorphic colour and mottling patterns.

  5. Upper Fort Union coals in western Powder River Basin, Wyoming: alluvial-plain deposits

    SciTech Connect

    Flores, R.M.; Hardie, J.K.; Coss, J.M.; Weaver, J.N.; Van Gosen, B.S.

    1984-04-01

    Stratigraphic distribution of coals and associated lithofacies in the upper Fort Union Formation (Paleocene) was investigated in outcrop and subsurface from southeast of Sussex to south of Buffalo, Wyoming. In this area, Ayers and Kaiser in 1982 proposed that upper Fort Union coals accumulated in deltas and interdeltas, and pinched out into a lake. Our study does not support these interpretations. The upper 1000 ft (300 m) of the Fort Union Formation in the western Powder River basin comprises interbedded conglomerates, conglomeratic sandstones, sandstones, siltstones, mudstones, carbonaceous shales, and coals. The conglomerates, consisting of pebbles and cobbles reworked from Mesozoic and Paleozoic rocks, are in scour-based bodies as thick as 25 ft (8 m). A 300-ft (90 m) thick, 12-mi (19 km) long conglomeratic channel-sandstone complex is in the lower part of the interval. In the upper part of the interval, conglomeratic single- and multistory channel sandstones reach thickness of 100 ft (30 m) and widths of 4000 ft (1200 m). These channel sandstones grade into overbank-floodplain sediments, which are interbedded with backswamp deposits of coals and carbonaceous shales. The conglomeratic channel sandstones are interbedded with coal beds as thick as 20 ft (6 m). These coal beds probably are laterally equivalent to the 178-ft (54 m) thick Sussex coal deposit to the east. Lithofacies associated with the coals in the western Powder River basin suggest an alluvial-plain paleoenvironment. The alluvial plain consisted of braided and meandering streams flanked by well-drained and poorly drained backswamps. These streams probably are northeasterly flowing tributaries of trunk streams.

  6. Architecture and development of the alluvial sediments of the Upper Jurassic Tordillo Formation in the Cañada Ancha Valley, northern Neuquén Basin, Argentina

    NASA Astrophysics Data System (ADS)

    López-Gómez, José; Martín-Chivelet, Javier; Palma, Ricardo M.

    2009-07-01

    The Upper Jurassic Tordillo Formation at Cañada Ancha area, northern Neuquén Basin, Argentina, comprises a multi-stage suit of predominantly alluvial sediments that is heterolithic in nature. In that suit, several lithofacies, architectural elements, and bounding surfaces of different order have been identified and their lateral and vertical distribution characterized. This analysis allowed the differentiation of 3 main units (lower, middle and upper), 20 subunits (C-1 to C-20), and the characterization of their alluvial styles. The lower unit (which comprises subunits C-1 to C-4) is mainly formed by fine- to medium-grained sandstones, which become medium- to coarse-grained towards the top. These sandstones characterize settings ranging from floodplains with isolated, unconfined flows, to more complex, vertically stacked, multi-storey sheet sandstones of braided fluvial systems. The middle unit (C-5 to C-10) is dominated by pale brown-grey fine-to coarse-grained sands and medium size subangular to angular conglomerates, which reflect amalgamated complexes of sandstone sheets and downstream accretion macroforms. Remarkably, this alluvial sedimentation was episodically punctuated by volcaniclastic flows. The upper unit (C-11 to C-20) consists of finer sediments, mainly pink to white fine-to medium grained sandstones and red to green siltstones. Towards the top, bioturbation becomes important, and also the presence of volcanosedimentary flows is noticeable. Fluvial settings include braided sheet sandstones with waning flood deposits evolving to isolated high-sinuosity fluvial systems, with flash flood deposits. At the top of this unit, facies may suggest marine influence. Vertical changes in the fluvial style result from both climatic and tectonic controls. A semiarid to arid climate and the active tectonism linked to the eastward migration of the Andean volcanic arc determined major bounding surfaces, fluvial style evolution and the presence of the volcano-sedimentary deposits. Different stages of high and low subsidence rates has been deduced from the vertical stacking of sediments.

  7. Ground-water quality in alluvial aquifers in the eastern Iowa basins, Iowa and Minnesota

    USGS Publications Warehouse

    Sadorf, Eric M.; Linhart, S. Michael

    2000-01-01

    The quality of shallow alluvial ground water that is used for domestic supplies in the Wapsipinicon, Cedar, Iowa, and Skunk River Basins (Eastern Iowa Basins) is described. Water samples from 32 domestic-supply wells were collected from June through July 1998. This study of ground-water quality in alluvial aquifers in the Eastern Iowa Basins is part of the U.S. Geological Survey's National Water-Quality Assessment Program. Calcium and bicarbonate were the dominant ions in solution, likely derived from the dissolution of carbonate minerals in the alluvial aquifer material. Concentrations of iron exceeded the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level (300 micrograms per liter) for drinking water in 53 percent of the samples, and 50 percent of the samples exceeded the Secondary Maximum Contaminant Level for manganese (50 micrograms per liter). pH and alkalinity increased and sulfate concentrations decreased with increasing well depth. Nitrite plus nitrate nitrogen was detected in 53 percent of the samples and exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 milligrams per liter for drinking water in 13 percent of the samples. Nitrite plus nitrate nitrogen concentrations were negatively correlated with well depth and positively correlated with percentage of oxygen saturation. Ammonia plus organic nitrogen concentrations were positively correlated with well depth, and ratios of nitrite plus nitrate to ammonia were positively correlated with percentage of oxygen saturation. The majority of samples, 72 percent, contained water recharged since the early 1950's. The recharge date of water was earlier in deeper wells. Nitrite plus nitrate and total pesticide concentrations were greater in more recently recharged water. Eight pesticides and eight pesticide metabolites were detected in ground-water samples. Atrazine was the most commonly detected pesticide, and metolachlor ethanesulfonic acid was the most commonly detected metabolite. No pesticide detections exceeded U.S. Environmental Protection Agency drinking-water Maximum Contaminant Levels. The effects of land use on ground-water quality also were examined. There was a positive correlation between percentage of land used for soybean production and concentrations of metolachlor, metolachlor ethanesulfonic acid, and metolachlor oxanilic acid in ground-water samples. Data from this study and from previous studies in the Eastern Iowa Basins were compared statistically by well type (domestic, municipal, and monitoring wells). Well depths were significantly greater in domestic and municipal wells than in monitoring wells. pH, calcium, sulfate, chloride, and atrazine concentrations were significantly higher in municipal-well samples than in domestic-well samples. pH and sulfate concentrations were significantly higher in municipal-well samples than in monitoring-well samples. Ammonia was significantly higher in domestic-well samples than in monitoring-well samples, chloride was significantly higher in monitoring-well samples than in domestic-well samples, and fluoride was significantly higher in domestic-well samples than in municipal-well samples.

  8. Alluvial dolines in the central Ebro basin, Spain: a spatial and developmental hazard analysis

    NASA Astrophysics Data System (ADS)

    Soriano, María Asuncíon; Simón, JoséLuis

    1995-03-01

    Alluvial dolines are abundant in Quaternary terraces and pediments overlying Neogene gypsum in the Zaragoza area (central Ebro basin). Spatial analysis and experimental simulation show that sulphate content in the groundwater, grain size of the detrital cover, topography of the Tertiary/Quaternary boundary, annual variation of the water table and thickness of the detrital cover are the main factors controlling their development. Taking into account these variables a theoretical spatial hazard model has been elaborated, expressed as a mathematical equation and a hazard map. Both experiments and field data show a high correspondance between two basic mechanisms of evacuation and subsidence (dragging slow subsidence and collapse of cavities) and two basic types of morphology and internal structure of dolines (basin doline — funnel structure and well doline — vault structures, respectively). A genetic classification of dolines and some evolutionary patterns based on these criteria are developed. Historical changes observed in doline distribution, as well as field surveys of urban damage and microtopographic profiles allow us to evaluate the present day activity of dolines. Local subsidence rates measured in urban areas range from 2.5 to 10 cm/year, although doline generation and reactivation in the whole area tend to be compensated by filling by human activity.

  9. Alluvial aquifer of the Cache and St. Francis River basins, northeastern Arkansas

    USGS Publications Warehouse

    Broom, Matthew E.; Lyford, Forest P.

    1981-01-01

    The alluvial aquifer underlies about 9,000 square miles of the study area. Well yields from the aquifer commonly are from 1,000 to 2,000 gallons per minute. Flow toward the main area of pumping stress is eastward from the Cache River and westward from the St. Francis River. The Memphis aquifer acts as a conduit through Crowleys Ridge for induced flow from the St. Francis River basin to the Cache River basn. Water use from the alluvial aquifer since the early 1900 's has been mostly for rice irrigation. Total pumpage for rice in 1978 was about 1,650 ,000 acre-feet, of which about 88 percent was pumped from the aquifer west of Crowleys Ridge. Water levels in wells west of the ridge in parts of Poinsett, Cross, and Craighead Counties in 1978 were 75 feet below land surface and declining about 2 feet per year. Digital-model analysis indicated that at the end of 1978 water was being removed from aquifer storage at the rate of 540,000 acre-feet per year, and streamflow, mostly from the Cache River and Bayou DeView, was being captured at the rate of 430,000 acre-feet per year. Projecting the 1978 pumping rate of 1,460,000 acre-feet per year, the pumping rate would have to be reduced by about 110,000 acre-feet per year by 1990 to sustain sufficient aquifer saturation for water needs through the year 2000 in all parts of Poinsett, Craighead, and Cross Counties west of Crowleys Ridge. (USGS)

  10. Modern sediment yield compared to geologic rates of sediment production in a semi-arid basin, New Mexico: Assessing the human impact

    USGS Publications Warehouse

    Gellis, A.C.; Pavich, M.J.; Bierman, P.R.; Clapp, E.M.; Ellevein, A.; Aby, S.

    2004-01-01

    In the semi-arid Arroyo Chavez basin of New Mexico, a 2.28 km2 sub-basin of the Rio Puerco, we contrasted short-term rates (3 years) of sediment yield measured with sediment traps and dams with long-term, geologic rates (???10 000 years) of sediment production measured using 10Be. Examination of erosion rates at different time-scales provides the opportunity to contrast the human impact on erosion with background or geologic rates of sediment production. Arroyo Chavez is grazed and we were interested in whether differences in erosion rates observed at the two time-scales are due to grazing. The geologic rate of sediment production, 0-27 kg m-2 a -1 is similar to the modern sediment yields measured for geomorphic surfaces including colluvial slopes, gently sloping hillslopes, and the mesa top which ranged from 0.12 to 1.03 kg m -2 a-1. The differences between modern sediment yield and geologic rates of sediment production were most noticeable for the alluvial valley floor, which had modern sediment yields as high as 3.35 kg m-2 a-1. The hydraulic state of the arroyo determines whether the alluvial valley floor is aggrading or degrading. Arroyo Chavez is incised and the alluvial valley floor is gullied and piped and is a source of sediment. The alluvial valley floor is also the portion of the basin most modified by human disturbance including grazing and gas pipeline activity, both of which serve to increase erosion rates. ?? 2004 John Wiley and Sons, Ltd.

  11. Paleoecological inferences of recent alluvial damming of a lake basin due to retrogressive permafrost thaw slumping

    NASA Astrophysics Data System (ADS)

    Quinlan, R.; Delaney, S.; Lamoureux, S. F.; Kokelj, S. V.; Pisaric, M. F.

    2014-12-01

    Expected climate impacts of future warming in the Arctic include thawing of permafrost landscapes in northern latitudes. Thawing permafrost is expected to have major consequences on hydrological dynamics, which will affect the limnological conditions of Arctic lakes and ponds. In this study we obtained a sediment core from a small lake (informally named "FM1") near Fort McPherson, Northwest Territories, Canada, with a large retrogressive thaw slump (nearly 1 kilometre in diameter) within its catchment. A radiocarbon date from the base of the FM1 sediment core suggests the lake formed between 990-1160 Cal AD. The analysis of aerial photographs indicate the thaw slump initiated between 1970-1990, and sediment geochemistry analysis indicated major changes in sediment content at 54-cm sediment core depth. Analyses of subfossil midge (Chironomidae) fossils inferred that, pre-slump, lake FM1 was shallow with a large bog or wetland environment, with midge assemblages dominated by taxa such as Limnophyes and Parametriocnemus. Post-thaw midge assemblages were dominated by subfamily Chironominae (Tribe Tanytarsini and Tribe Chironomini) taxa, and the appearance of deepwater-associated taxa such as Sergentia suggests that lake FM1 deepened, possibly as a result of alluvial damming from slump materials washing into the lake near its outlet. Most recent stratigraphic intervals infer a reversion back to shallower conditions, with a slight recovery of bog or wetland-associated midge taxa, possibly due to rapid basin infilling from increased deposition rates of catchment-derived materials. Results emphasize that there may be a variety of different outcomes to Arctic lake and pond ecosystems as a result of permafrost thawing, contingent on system-specific characteristics such as slump location relative to the lake basin, and relative inflow and outflow locations within the lake basin.

  12. Groundwater recharge and agricultural contamination in alluvial fan of Eastern Kofu basin, JAPAN

    NASA Astrophysics Data System (ADS)

    Nakamura, T.

    2009-12-01

    Agriculture has significant effects on the rate and composition of groundwater recharge. The chemical loading into groundwater have been dominated by the constituents derived directly or indirectly from agricultural practices and additives. The contamination of groundwater with nitrate is a major public health and environmental concern around the world. The inorganic constituents like, K+, Ca2+, Mg2+, SO42-, Cl- and variety of other minor elements of groundwater are often used as agricultural additives; and the natural occurrence of these elements are dominated by the agricultural sources. A recent study has reported that Kofu basin groundwater aquifer is contaminated by nitrate from agricultural areas because of the fertilizer application for the orchard (Kazama and Yoneyama, 2002; Sakamoto et al., 1997, Nakamura et al., 2007). The water-oxygen and hydrogen stable isotope (δ18O and δD) and nitrate-nitrogen stable isotope (δ15N) of groundwater, river water and precipitation samples were investigated to identify the source of groundwater and nitrate nitrogen contamination in groundwater in the Fuefukigawa and Hikawa_Kanegawa alluvial fans in Kofu basin. The plot of δD versus δ18O values of groundwater, river water and precipitation samples suggest that the groundwater is a mixture of precipitation and river water. And nitrate-nitrogen isotope values have suggested the nitrate contamination of groundwater is from agricultural area. The study revealed positive correlation between groundwater δ18O values and NO3-, Cl-, SO42-, Ca2+, Mg2+ concentration, which shows the agricultural contamination is carried by the recharge of groundwater from precipitation in alluvial fan. Whereas, NO3-, Cl-, SO42-, Ca2+, Mg2+ are diluted by the river water recharges. This study showed the quality of groundwater is resulted from the mixing of water from the different source during the groundwater recharge in the study area. References Kazama F, Yoneyama M (2002) Nitrogen generation in the Yamanashi prefecture and its effects on the groundwater pollution. Int. Envir. Science Vol. 15:293-298. (in Japanese) Sakamoto Y, Nakamura F, Kazama F (1990) Spatial Distribution of Nitrate Concentration in Groundwater-Derived Potable. Reports of the Faculty of Engineering Yamanashi University Vol.41:139-144. (in Japanese) Nakamura T, Satake H, Kazama F (2007) Effects of groundwater recharge on nitrate-nitrogen loadings. Journal of Water and Environment Technology Vol.5:87-93.

  13. Analysis of the Carmel Valley alluvial ground-water basin, Monterey County, California

    USGS Publications Warehouse

    Kapple, Glenn W.; Mitten, Hugh T.; Durbin, Timothy J.; Johnson, Michael J.

    1984-01-01

    A two-dimensional, finite-element, digital model was developed for the Carmel Valley alluvial ground-water basin using measured, computed, and estimated discharge and recharge data for the basin. Discharge data included evapotranspiration by phreatophytes and agricultural, municipal, and domestic pumpage. Recharge data included river leakage, tributary runoff, and pumping return flow. Recharge from subsurface boundary flow and rainfall infiltration was assumed to be insignificant. From 1974 through 1978, the annual pumping rate ranged from 5,900 to 9,100 acre-feet per year with 55 percent allotted to municipal use principally exported out of the valley, 44 percent to agricultural use, and 1 percent to domestic use. The pumpage return flow within the valley ranged from 900 to 1,500 acre-feet per year. The aquifer properties of transmissivity (about 5,900 feet squared per day) and of the storage coefficient (0.19) were estimated from an average alluvial thickness of 75 feet and from less well-defined data on specific capacity and grain-size distribution. During calibration the values estimated for hydraulic conductivity and storage coefficient for the lower valley were reduced because of the smaller grain size there. The river characteristics were based on field and laboratory analyses of hydraulic conductivity and on altitude survey data. The model is intended principally for simulation of flow conditions using monthly time steps. Time variations in transmissivity and short-term, highrecharge potential are included in the model. The years 1974 through 1978 (including "pre-" and "post-" drought) were selected because of the extreme fluctuation in water levels between the low levels measured during dry years and the above-normal water levels measured during the preceding and following wet years. Also, during this time more hydrologic information was available. Significantly, computed water levels were generally within a few feet of the measured levels, and computed flows were close to gaged riverflows for this simulation. However, the nonuniqueness of solutions with respect to different sets of data indicates the model does not necessarily validate the correctness of the individual variables. The model might be improved with additional knowledge of the distribution of confining sediments in the lower end of the valley and the aquifer properties above and below them. The solution algorithm could account for confinement or partial confinement in the lower end of the valley plus contributions from the Tularcitos aquifer.

  14. Estimates of net infiltration in arid basins and potential impacts on recharge and solute flux due to land use and vegetation change

    NASA Astrophysics Data System (ADS)

    Robertson, Wendy Marie; Sharp, John M.

    2015-03-01

    Human impacts on land use and vegetation in arid basins have, in some regions, altered infiltration, recharge, and groundwater chemistry. However, some modeling approaches currently used do not account for these effects. In the Trans-Pecos region of Texas the presence of modern water, increasing groundwater NO3- concentrations, and vadose zone cores flushed of naturally accumulated solutes belie the notion that basin groundwater is unaffected by overlying land use and vegetation change. Recharge to the Trans-Pecos basins is spatially and temporally variable, and due to human impacts it has likely changed since pre-western settlement time (circa 1850s). By using the INFIL 3.0.1 model, a spatially distributed model of net infiltration, the volume and spatial distribution of net infiltration was examined for two basins, Wild Horse/Michigan Flats and Lobo/Ryan Flats, with model simulations designed to examine the effects of irrigated agriculture and human impacts on vegetation. Model results indicate that recharge to the basins is not limited to mountain-front zones and discrete features (i.e., alluvial channels), rather, irrigation return flow contributes an estimated 6.3 × 107 m3 (408 mm) of net infiltration over 40 yrs and net infiltration on the basin floors could contribute between 7% and 11.5% of annual basin recharge. Model results also indicate that net infiltration may be higher under current vegetation regimes than in pre-western settlement conditions; the removal of thick dense grasslands in INFIL model simulations enhanced net infiltration by 48% or more. Results from distributed models (like INFIL) improve upon scientific understanding of the links between vegetation regime and hydrological processes; this is important for the sustainable management of arid basin aquifers in Texas and elsewhere.

  15. Great Basin semi-arid woodland dynamics during the late quaternary

    SciTech Connect

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E.

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  16. A Synthetic View of Delta Progradation, Distributary Channel Stability and Alluvial Aggradation in Terms of the Control of Basin Water Depth

    NASA Astrophysics Data System (ADS)

    Muto, T.

    2014-12-01

    Recent progress in experimental stratigraphy of river deltas has brought an implication that basin water depth seriously affects not only delta progradation, but also distributary channel behavior and alluvial aggradation of the delta plain. A series of experiments conducted with differential basement suggests that a prograding delta can retain its isotropic shoreline configuration even though there is significant variation in basin water depth in the transverse direction, and thus that local basin water depth affects local residence time and avulsion frequency of distributary channels. With deeper basin water, a delta progrades slowly, distributary channels migrate slowly and avulse less frequently, and the feeder alluvial system aggrades slowly. Another series of experiments, which were conducted to produce a 2D graded alluvial channel, reveals that a delta facing a very deep water basin does not prograde, its distributary channels do not migrate, and the feeder alluvial system does not aggrade at all (i.e. the state of grade). These experimental facts imply a synthetic understanding of delta progradation, distributary channel stability and alluvial aggradation, in terms of the control of basin water depth. This novel understanding can be expressed in part by a simple geometrical model. Dimensionless rates of (1) delta progradation, (2) channel migration and (3) alluvial aggradation are expressed with an identical numerical formula that can be specified only with dimensionless basin water depth and alluvial slope normalized with the delta's foreset slope. Values of those dimensionless rates, ranging between 0 and 1, denote how close the feeder alluvial system is to grade: 0 for grade and 1 for perfect aggradation. The three dimensionless rates, or grade index, are also applicable to a river delta growing with sea level change, as far as it retains an isotropic shoreline configuration.

  17. Changes in alluvial architecture associated with Eocene hyperthermals: Preliminary results from the Bighorn Basin Coring Project

    NASA Astrophysics Data System (ADS)

    Acks, R.; Kraus, M. J.

    2012-12-01

    The Paleocene-Eocene Thermal Maximum (PETM) was followed by two lesser hyperthermal events: ETM2 and H2 both at ~53.7 Ma. The carbon isotope excursion for ETM2 was approximately half that of the PETM and the H2 excursion even smaller, indicating lower increases in temperature than during the PETM. The paleohydrologic responses to these events are less well understood than the response to PETM warming. Although the ETM2 and H2 events are better known from marine than continental strata, both events have been identified from outcrops of the alluvial Willwood Formation from the Deer Creek and Gilmore Hill areas of the Bighorn Basin, Wyoming (Abels et al., 2012). Here, we analyze two cores drilled from stratigraphically equivalent Willwood strata from Gilmore Hill. The cores provide an opportunity to examine the impact of these events on the architecture of fluvial strata. Willwood strata are composed largely of channel sandstones, heterolithic deposits generated by channel avulsion, and paleosols that formed on overbank deposits. The paleosols provide qualitative and quantitative information on changes in soil moisture and precipitation through this interval. The cores also show a distinct change in the stacking of paleosols The core is subdivided into three parts: (1) the lowest ~third has thinner, more densely spaced paleosols, (2) the middle has thicker paleosols that are more widely spaced, and (3) the upper third has thicker and more common channel sandstones interspersed with avulsion deposits and fewer red paleosols; this corresponds to the hyperthermal interval. In particular, a ~20 m thick sandstone complex caps the section and appears to truncate part of the hyperthermal interval. Although vertical variations in alluvial architecture can reflect tectonic or climatic change, the correspondence of the sandstone-rich part of the cores with the hyperthermals suggests climate was the major control on their formation. Thick purple paleosols associated with the hyperthermals at Deer Creek suggest wetter conditions, and our preliminary interpretation is that a change to wetter conditions caused increased discharge and deposition of coarser (sandy) sediment. The thick sandstone complex at Gilmore Hill is underlain by paleosols with abundant calcrete nodules, which indicate drier soil conditions prior to deposition of the sandstone, and the change from drier to wetter conditions probably also caused increased sediment yield.

  18. Hydrogeologic features of the alluvial deposits in the Greybull River valley, Bighorn Basin, Wyoming

    USGS Publications Warehouse

    Cooley, M.E.; Head, W.J.

    1979-01-01

    The alluvial aquifer along the Greybull River in Wyoming, consists principally of the Greybull terrace doposits and flood-plain alluvium but also includes Burlington terrace deposits east of Burlington, the McKinnie terrace, and the younger, generally undissected alluvial-fan deposits. Well-log data and 18 surface-resistivity measurements at four localities indicate that the thickness of the alluvial aquifer is as much as 60 feet thick only near Burlington and Otto. The most favorable area for development of ground water from the alluvial aquifer is near Burlington and Otto where relatively large amounts of water can be obtained from the Greybull terrace deposits and the flood-plain alluvium. Elsewhere, the deposits of the alluvial aquifer yield only small amounts of water to wells. (Woodard-USGS)

  19. Hydrogeology and simulation of flow between the alluvial and bedrock aquifers in the upper Black Squirrel Creek basin, El Paso County, Colorado

    USGS Publications Warehouse

    Watts, K.R.

    1995-01-01

    Anticipated increases in pumping from the bedrock aquifers in El Paso County potentially could affect the direction and rate of flow between the alluvial and bedrock aquifers and lower water levels in the overlying alluvial aquifer. The alluvial aquifer underlies about 90 square miles in the upper Black Squirrel Creek Basin of eastern El Paso County. The alluvial aquifer consists of unconsolidated alluvial deposits that unconformably overlie siltstones, sandstones, and conglomerate (bedrock aquifers) and claystone, shale, and coal (bedrock confining units) of the Denver Basin. The bedrock aquifers (Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) are separated by confining units (upper and lower Denver and the Laramie confining units) and overlie a relatively thick and impermeable Pierre confining unit. The Pierre confining unit is assumed to be a no-flow boundary at the base of the alluvial/ bedrock aquifer system. During 1949-90, substantial water-level declines, as large as 50 feet, in the alluvial aquifer resulted from withdrawals from the alluvial aquifer for irrigation and municipal supplies. Average recharge to the alluvial aquifer from infiltration of precipitation and surface water was an estimated 11.97 cubic feet per second and from the underlying bedrock aquifers was an estimated 0.87 cubic foot per second. Water-level data from eight bedrock observation wells and eight nearby alluvial wells indicate that, locally, the alluvial and bedrock aquifers probably are hydraulically connected and that the alluvial aquifer in the upper Black Squirrel Creek Basin receives recharge from the Denver and Arapahoe aquifers but-locally recharges the Laramie-Fox Hills aquifer. Subsurface-temperature profiles were evaluated as a means of estimating specific discharge across the bedrock surface (the base of the alluvial aquifer). However, assumptions of the analytical method were not met by field conditions and, thus, analyses of subsurface-temperature profiles did not reliably estimate specific discharge across the bedrock surface. The vertical hydraulic diffusivity of a siltstone and sandstone in the lower Denver confining unit was estimated, by an aquifer test, to be about 8 x 10'4 square foot per day. Physical and chemical characteristics of water from the bedrock aquifers in the study area generally differ from the physical and chemical characteristics of water from the alluvial aquifer, except for the physical and chemical characteristics of water from one bedrock well, which is completed in the Laramie-Fox Hills aquifer. In the southern part of the study area, physical and chemical characteristics of ground water indicate downward flow of water from the alluvial aquifer to the Laramie-Fox Hills aquifer. A three-dimensional numerical model was used to evaluate flow of water between the alluvial aquifer and underlying bedrock. Simulation of steady-state conditions indicates that flow from the bedrock aquifers to the alluvial aquifer was about 7 percent of recharge to the alluvial aquifer, about 0.87 cubic foot per second. The potential effects of withdrawal from the alluvial and bedrock aquifers at estimated (October 1989 to September 1990) rates and from the bedrock aquifers at two larger hypothetical rates were simulated for a 50-year projection period. The model simulations indicate that water levels in the alluvial aquifer will decline an average of 8.6 feet after 50 years of pumping at estimated October 1989 to September 1990 rates. Increases in withdrawals from the bedrock aquifers in El Paso County were simulated to: (1) Capture flow that currently discharges from the bedrock aquifers to springs and streams in upland areas and to the alluvial aquifer, (2) induce flow downward from the alluvial aquifer, and (3) accelerate the rate of waterlevel decline in the alluvial aquifer.

  20. Tectonic controls of the North Anatolian Fault System (NAFS) on the geomorphic evolution of the alluvial fans and fan catchments in Erzincan pull-apart basin; Turkey

    NASA Astrophysics Data System (ADS)

    Sarp, Gulcan

    2015-02-01

    The Erzincan pull-apart basin is located in the eastern section of the North Anatolian Fault System (NAFS). The tectonic evolution of this basin is mostly controlled by strike slip master faults of the NAFS. This study examines the topography-structure relationships in an effort to evaluate the tectonic signatures in the landscape, paying special attention to recent tectonic activity. In the study, the main focus is on the tectonic controls of the NAFS on the geomorphic evolution of alluvial fans and fan catchments in the Erzincan pull-apart basin. The observations of the amount of tilting of the alluvial fans (?) and its relation with morphometric (Asymmetry Factor (AF), Hypsometric Integral (HI), Fractal analysis of drainage networks (D)) properties of the fan catchments provide valuable information about the tectonic evolution of the basin area. The results of the analyses showed that the alluvial fan and fan catchment morphology in the pull-apart basin are mainly controlled by the ongoing tectonic activity of the NAFS. The fault system in the basin has controlled the accommodation space by causing differential subsidence of the basin, and aggradation processes by causing channel migration, channel incision and tilting the alluvial fans.

  1. Discriminating sediment archives and sedimentary processes in the arid endorheic Ejina Basin, NW China using a robust geochemical approach

    NASA Astrophysics Data System (ADS)

    Yu, Kaifeng; Hartmann, Kai; Nottebaum, Veit; Stauch, Georg; Lu, Huayu; Zeeden, Christian; Yi, Shuangwen; Wünnemann, Bernd; Lehmkuhl, Frank

    2016-04-01

    Geochemical characteristics have been intensively used to assign sediment properties to paleoclimate and provenance. Nonetheless, in particular concerning the arid context, bulk geochemistry of different sediment archives and corresponding process interpretations are hitherto elusive. The Ejina Basin, with its suite of different sediment archives, is known as one of the main sources for the loess accumulation on the Chinese Loess Plateau. In order to understand mechanisms along this supra-regional sediment cascade, it is crucial to decipher the archive characteristics and formation processes. To address these issues, five profiles in different geomorphological contexts were selected. Analyses of X-ray fluorescence and diffraction, grain size, optically stimulated luminescence and radiocarbon dating were performed. Robust factor analysis was applied to reduce the attribute space to the process space of sedimentation history. Five sediment archives from three lithologic units exhibit geochemical characteristics as follows: (i) aeolian sands have high contents of Zr and Hf, whereas only Hf can be regarded as a valuable indicator to discriminate the coarse sand proportion; (ii) sandy loess has high Ca and Sr contents which both exhibit broad correlations with the medium to coarse silt proportions; (iii) lacustrine clays have high contents of felsic, ferromagnesian and mica source elements e.g., K, Fe, Ti, V, and Ni; (iv) fluvial sands have high contents of Mg, Cl and Na which may be enriched in evaporite minerals; (v) alluvial gravels have high contents of Cr which may originate from nearby Cr-rich bedrock. Temporal variations can be illustrated by four robust factors: weathering intensity, silicate-bearing mineral abundance, saline/alkaline magnitude and quasi-constant aeolian input. In summary, the bulk-composition of the late Quaternary sediments in this arid context is governed by the nature of the source terrain, weak chemical weathering, authigenic minerals, aeolian sand input, whereas pedogenesis and diagenesis exert only limited influences. Hence, this study demonstrates a practical geochemical strategy supplemented by grain size and mineralogical data, to discriminate sediment archives and thereafter enhance our ability to offer more intriguing information about the sedimentary processes in the arid central Asia.

  2. Hydrogeologic features of the alluvial deposits in the Owl Creek Valley, Bighorn Basin, Wyoming

    USGS Publications Warehouse

    Cooley, M.E.; Head, W.J.

    1982-01-01

    The alluvial acquifer principally of the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits and consists subordinately of alluvial-fan deposits. Thickness of the alluvial aquifer is generally 20 to 40 feet. Dissolved-solids concentration of water in the alluvial aquifer ranges from about 500 to more than 3,000 milligrams per liter. The most favorable areas for groundwater development are the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits; however, in much of these units, the water contains more than 2,000 milligrams per liter of dissolved solids. Measurements of specific conductance of the flow of Owl Creek indicate a progressive increase in the down stream direction and range between 15 and 355 micromhos per centimeter at 25C per mile. The increases are due to return flow of irrigation water, inflow from tributaries, and inflow from groundwater. Conspicuous terraces in Owl Creek Valley included an unnamed terrace at 500 feet above Owl Creek, the Embar Ranch terrace 160 to 120 feet above the creek, and the Arapahoe Ranch terrace 50 to 20 feet above the creek. (USGS)

  3. S2-Project: Near-fault earthquake ground motion simulation in the Sulmona alluvial basin

    NASA Astrophysics Data System (ADS)

    Faccioli, E.; Stupazzini, M.; Galadini, F.; Gori, S.

    2008-12-01

    Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http://nuovoprogettoesse2.stru.polimi.it/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et al., 2003). In particular, while "the OpenSHA collaboration model envisions scientists developing their own attenuation relationships and earthquake rupture forecasts, which they will deploy and maintain in their own systems" , the main purpose of S2 project is to provide a flexible computational tool for SHA, primarily suited for the needs of DPC, which not necessarily are scientific needs. Within S2, a crucial issue is to make alternative approaches available to quantify the ground motion, with emphasis on the near field region. The SHA architecture envisaged will allow for the use of ground motion descriptions other than those yielded by empirical attenuation equations, for instance user generated motions provided by deterministic source and wave propagation simulations. In this contribution, after a brief presentation of Project S2, we intend to illustrate some preliminary 3D scenario simulations performed in the alluvial basin of Sulmona (Central Italy), as an example of the type of descriptions that can be handled in the future SHA architecture. In detail, we selected some seismogenic sources (from the DISS database), believed to be responsible for a number of destructive historical earthquakes, and derive from them a family of simplified geometrical and mechanical source models spanning across a reasonable range of parameters, so that the extent of the main uncertainties can be covered. Then, purely deterministic (for frequencies < 2Hz) and hybrid deterministic- stochastic source and propagation simulations are carried out for different fault rupture scenarios (but including important features such as the dominant near-surface geology), and the results in terms of representative ground motion parameters appropriately enveloped. The fully 3D problem is solved using the Spectral Element (SE) method, extensively published by Faccioli and his co-workers, and Quarteroni and co- workers, starting from 1996, and the computational code GeoELSE (http://GeoELSE.stru.polimi.it/). Finally, numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near-fault regions elsewhere. Based on the results of this work, the unfavorable interaction between fault rupture, radiation mechanism and complex geological conditions may give rise to large values of peak ground velocity (exceeding 1 m/s) even in low-to-moderate seismicity areas, and therefore increase considerably the level of seismic risk, especially in highly populated and industrially active regions, such as the Central Italy.

  4. Magnetostratigraphy of The Astronomically-forced Alluvial Fan To Lacustrine Sequences of The Teruel Basin (late Miocene, Spain)

    NASA Astrophysics Data System (ADS)

    van Dam, J.; Aziz, H. Abdul; Hilgen, F. J.; Krijgsman, W.

    During the last years, more and more examples of allocyclic, astronomical forced variations in the continental record have been documented. Sedimentary hiatuses, tra- ditionally regarded as the primary reason for the absence of clear patterns of orbital signature in the terrestrial domain, may be absent or short, given the appropriate set- ting. Spanish endoreic basins, for instance, form a ideal setting for the registration of orbital-forced climate change, as has been demonstrated for the Middle Miocene distal-alluvial fan-floodplain to lacustrine deposits of the Calatayud Basin. Astronom- ical forcing of sedimentary cycles has also been demonstrated in the Late Miocene distal alluvial fan to lacustrine sequences of the Teruel Basin. The early Late Miocene Cascante and Cañizar sections South of the town of Teruel show distinct cyclic bed- ding of red and/or green mottled mudstones alternating with white carbonate beds, whereby the alternation is mainly controlled by precession and eccentricity. The car- bonate beds are interpreted as (shallow) lake highstands, which occur in response to submergence of the alluvial fan distal plain. Small mammal teeth have been recov- ered from organic-richer layers at the base of the carbonate cycles in the Cascante and Cañizar sections. The recovery of mammal remains in terrestrial Milankovitch forced settings is crucial for several reasons: 1) it provides a first approximate age estimation for the sequence, thereby constraining other sources of temporal information such as magnetostratigraphy; 2) it infers very accurate ages of the mammal localities after as- tronomical tuning of the cyclic patterns; 3) it formulates hypotheses on the climatic regime and its variability using precise correlations to the insolation curve and in- terpretation of phase relations; and 4) it confronts the astronomically-based climatic reconstruction with the paleoecological reconstructions and faunal changes observed in the mammals themselves. This will lead to a better understanding of the nature of the response terrestrial organisms exhibit to climatic change. Based on the cyclo- and magnetostratigraphy, two age models for the sections (10.1-9.4 Ma; 10.3-9.6 Ma) are possible. However, spectral analysis results and estimated duration of subchrons indicate a preference for the younger age model. Additional sampling for mammals and paleomagnetism is needed to solve the problem of the age models, to date more 1 precisely mammal subzones J1, 2 and 3, and to establish the exact relations between changes in the mammal communities and short- and long-term astronomical cycles. 2

  5. GIS Analysis of Size Relationships between Drainage Basins and Alluvial Fans

    NASA Astrophysics Data System (ADS)

    Wright, S. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

    2014-12-01

    Imagery from the global database of modern sedimentary basins compiled by Weissman et al. (2010) allows us to test whether a size relationship between drainage basin area and distributive fluvial system (DFS) area exists. We are testing this hypothesis using a combination of SRTM-based digital elevation models and Landsat satellite imagery in ArcGIS. Sedimentary basins are delineated by preforming a Gaussian smoothing on the DEM, followed by optimal edge detection through application of a modified Canny edge detector. The pour points defining the link between contributing hydrologic basins and these sedimentary basins are then located by generating a stream network in ArcGIS and intersecting the stream network arcs with the sedimentary basin polygons. From these pour points we delineate the adjacent contributing drainage basin using the watershed tool in ArcGIS. We manually digitize the boundary and geometry of the DFS identified for each drainage basin, using the higher resolution imagery found on Google Earth for visual confirmation if the scale or resolution of the Landsat imagery requires it. We then extract drainage basins and DFS polygon parameters and calculate areal extents in order to evaluate whether such a size relationship exists within basins, regionally across several basins, or across different basin types (e.g., endorheic vs exhoreic). A limitation of this approach is that we cannot evaluate sediment volumes, only aerial coverage. Results from this study may provide a better understanding of extrabasinal processes that control DFS shape and size.

  6. Pedogenic and early diagenetic processes in Palaeogene alluvial fan and lacustrine deposits from the Sado Basin (S Portugal)

    NASA Astrophysics Data System (ADS)

    Pimentel, N. L. V.

    2002-04-01

    The Palaeogene deposits of the Sado Basin were deposited in a continental basin that shows a typical pattern with alluvial fans system in the margins of the basin, passing towards distal areas of mudflat facies where, in some areas, the installation of shallow water bodies favoured the development of palustrine conditions. The deposits of this basin vary form coarse conglomerates and sandstones to palustrine carbonates. These sediments were affected by pedogenesis and early diagenetic processes that promoted important modifications on their primary features. These modifications have been studied by the analyses of four profiles, developed on proximal, middle and distal fan deposits and the fourth one on lacustrine deposits. The overall analyses of the sedimentological, pedogenic, diagenetic features and their relationships indicate that three main processes took place throughout the basin: soil formation, palygorskite neoformation and dolomitization. Soil formation processes led to illuviation of clays and carbonate precipitation mostly around roots. Pedogenic carbonates increase towards distal areas, whereas hydromorphic features are present throughout the basin. Palygorskite neoformation was partially diagenetic, being maximum in proximal areas and palustrine deposits. This neoformation is attributed to the percolation of alkaline Mg-rich soil and groundwaters through smectitic-rich sediments, promoting important clay transformation. Dolomitization was an early diagenetic process that occurred mainly in carbonate-rich deposits of distal and lacustrine environments, as a result of the increasing Mg/Ca ratio of the percolating groundwaters. In all these processes there has been a close spatial and temporal interplay between pedogenesis and diagenesis, driven by the chemistry of soil particles and groundwaters.

  7. Tectonic significance of Upper Cretaceous alluvial-fan deposits in the Peninsular Ranges forearc basin complex, Baja California (Mexico)

    SciTech Connect

    Fulford, M.; Busby-Spera, C. )

    1990-05-01

    Recent evidence suggests that forearc basins, previously depicted as broad downwarps, may experience syndepositional faulting and/or folding. The upper Campanian El Gallo Formation, which was deposited along the northern margin of the Rosario embayment of the peninsula Ranges forearc basin complex, records tilting of the underlying arc massif basement contemporaneous with dissection of the arc source terrane. The La Escarpa member at the base of the El Gallo Formation consists of a 100-180-m thick upward-fining sequence, interpreted as a retrogradational proximal to distal alluvial-fan deposit. Overlying the La Escarpa member is the 1,000-m thick El Disecado member, which lies at the top of the El Gallo Formation and consists of sandy fluvial deposits. Conglomerate clast counts from the La Escarpa member and point-count data from sandstones throughout the El Gallo Formation show an upsection increase in granitic and metasedimentary rock fragments relative to volcanic/metavolcanic rock fragments, reflecting unroofing and progressive headward erosion of the source terranes in the Peninsular Ranges. Paleocurrent data from the La Escarpa and El Disecado members suggest a rotation of approximately 110{degree} with time, from west-northwesterly to southerly, reflecting tilting of the basin floor. This may have been accomplished by downdropping along an east-west-trending fault that divided the Rosario embayment into separate subbasins during the Cretaceous.

  8. Predicting the Affects of Climate Change on Evapotranspiration and Agricultural Productivity of Semi-arid Basins

    NASA Astrophysics Data System (ADS)

    Peri, L.; Tyler, S. W.; Zheng, C.; Pohll, G. M.; Yao, Y.

    2013-12-01

    Many arid and semi-arid regions around the world are experiencing water shortages that have become increasingly problematic. Since the late 1800s, upstream diversions in Nevada's Walker River have delivered irrigation supply to the surrounding agricultural fields resulting in a dramatic water level decline of the terminal Walker Lake. Salinity has also increased because the only outflow from the lake is evaporation from the lake surface. The Heihe River basin of northwestern China, a similar semi-arid catchment, is also facing losses from evaporation of terminal locations, agricultural diversions and evapotranspiration (ET) of crops. Irrigated agriculture is now experiencing increased competition for use of diminishing water resources while a demand for ecological conservation continues to grow. It is important to understand how the existing agriculture in these regions will respond as climate changes. Predicting the affects of climate change on groundwater flow, surface water flow, ET and agricultural productivity of the Walker and Heihe River basins is essential for future conservation of water resources. ET estimates from remote sensing techniques can provide estimates of crop water consumption. By determining similarities of both hydrologic cycles, critical components missing in both systems can be determined and predictions of impacts of climate change and human management strategies can be assessed.

  9. Integrative geomorphological mapping approach for reconstructing meso-scale alluvial fan palaeoenvironments at Alborz southern foothill, Damghan basin, Iran

    NASA Astrophysics Data System (ADS)

    Büdel, Christian; Majid Padashi, Seyed; Baumhauer, Roland

    2013-04-01

    Alluvial fans and aprons are common depositional features in general Iranian geomorphology. The countries major cities as well as settlements and surrounding area have often been developed and been built up on this Quaternary sediment covers. Hence they periodically face the effects of varying fluvial and slope-fluvial activity occurring as part of this geosystem. The Geological Survey of Iran therefore supports considerable efforts in Quaternary studies yielding to a selection of detailed mapped Quaternary landscapes. The studied geomorphologic structures which are settled up around an endorheic basin in Semnan Province represent a typical type of landform configuration in the area. A 12-km-transect was laid across this basin and range formation. It is oriented in north-south direction from the southern saltpan, called "Kavir-e-Haj Aligholi"/"Chah-e-Jam" ("Damghan Kavir"), across a vast sandy braided river plain, which is entering from the north east direction of the city of Shahroud. At its northern rim it covers alluvial sediment bodies, which are mainly constituted by broad alluvial aprons, fed by watersheds in Alborz Mountains and having their genetic origins in Mio-/Pliocene times. During this study a fully analytical mapping system was used for developing a geodatabase capable of integrating geomorphological analyses. Therefore the system must provide proper differentiation of form, material and process elements as well as geometric separation. Hence the German GMK25 system was set up and slightly modified to fit to the specific project demands. Due to its structure it offers most sophisticated standards and scale independent hierarchies, which fit very well to the software-determinated possibilities of advanced geodatabase applications. One of the main aspects of mapping Quaternary sediments and structures is to acquire a proper description and systematic correlation and categorization of the belonging mapping-objects. Therefore the team from GSI and University of Würzburg performs additional geochronologic and stratigraphic studies of different alluvial surfaces in the investigation area. Relative and absolute dating methods are applied, as well as non-invasive and invasive methods for studying subsurface sedimentation and layering. The ongoing mapping work has revealed a progradational sequence of at least five more or less dissected surfaces of alluvial deposits. These can be distinguished by optically taken morphometric and spectrometric parameters and material reflectance using remote sensing imagery data. An important role for geomorphometric measurements and landform identification was occupied by DEM data. In the field these parameters could be correlated with differently developed covers of desert pavement, and changes in curvature, roughness and levels of sediment surfaces. The studied alluvium has been formed by several phases of debris flow activity and braided river dynamics over a distance of more than 3.5 km and is reworked recently. Gradual differences in structure and form may be linked to changes in depositional process and quaternary environmental development as well as neotectonic activity. Future correlation between alluvium and sediment cores from the playa is targeting on better understanding of depositional milieus during activity phases.

  10. Palaeohydrological and palaeoecological studies on South Cameroonian alluvial sedimentary basins - New evidence on the palaeoenvironmental evolution of western Central Africa since the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Sangen, M.

    2009-04-01

    A new valuable and innovative contribution will be presented to ascertain the timing and extension of climatic and ecological changes in western equatorial Africa. Main focus is laid on the dynamics of climate, fluvial systems and the high sensitive tropical ecosystems (dense evergreen and semi-deciduous rain forest and savanna-rain forest margin) since the Late Pleistocene (~50 kyrs. BP). For this purpose extended fieldworks were carried out in South Cameroon (2004-2008) by the ReSaKo-Project (sub-project of DFG-Project 510) with abundant investigations on alluvial sedimentary basins of equatorial tropical fluvial systems. Suitable alluvial sediment-archives for palaeoenvironmental research were uncovered along selected braiding, meandering and anabranching/anastomosing reaches of major southwestern, into the Gulf of Guinea (Ntem, Nyong and Sanaga) and southeastern, into the Congo basin (Boumba, Dja and Ngoko) draining rivers (RUNGE et al. 2006, SANGEN 2008). Among geomorphological investigations and cross section discussions, 150 corings (Edelman, 20 cm layers) reaching maximum depths of 550 cm were carried out on river benches, levees, cut-off and periodical branches, islands and terraces as well as in seasonal inundated floodplains and backswamps. Corresponding sedimentary profiles and catenae recovered multilayered, sandy to clayey alluvia containing sedimentary form-units and palaeosurfaces which contribute to the reconstruction of palaeoenvironmental conditions in western equatorial Africa. Several (59) radiocarbon (AMS) dated samples (Erlangen and Lecce) from fossil organic layers and macro-rests embedded in these units yielded Late Pleistocene to recent ages (14C-ages around 48 to 0.2 kyrs. BP), spanning also the Last Glacial Maximum (LGM) and Holocene record. Abrupt grain-size modifications and alternating form-units (sandy and clayey layers, palaeosurfaces) in the stratigraphic records display fluctuations in the fluvial-morphological response of the fluvial systems to climatic variability and other extrinsic and intrinsic impacts. Although the sedimentary record varies among the studied river reaches, fossil organic sediment layers (palaeosurfaces) containing valuable proxy data were found in almost all alluvia basins of examined southern Cameroonian rivers. Around 56 ^13C-values corresponding to the dated samples (-31.4 to -18.0 ) evidence that despite major disturbances of the African rain forest over geological times (MALEY 2001) mainly rain forest ecosystems have prevailed during the corresponding time periods, presumably as gallery forests, which were able to persist in this fluvial habitat ("fluvial refuge"), even during arid periods (e.g. LGM). The results are consistent with earlier findings from lacustrine (SERVANT & SERVANT-VILDARY 2000), marine (WELDEAB et al. 2007) and additional sediment archives (GASSE et al. 2008) and will add additional insights and information to the unravelling of the complex respond of the African monsoon, the Central African ecosystems and fluvial systems to Late Quaternary climatic and environmental fluctuations within a globally teleconnected system. References: GASSE, F., CHALIé, F., VINCENS, A., WILLIAMS, M.A.J. & WILLIAMSON, D. (2008): Climatic patterns in equatorial and southern Africa from 30,000 to 10,000 years ago reconstructed from terrestrial and near-shore proxy data. Quaternary Science Reviews, 27 (25-26), 2316-2340. MALEY, J. (2001): The impact of arid phases on the African rain forest through geological history. In: WEBER, W., WHITE, L., VEDDER, A., NAUGHTON-TREVES, L. (Eds.): African rain forest ecology and conservation - An interdisciplinary perspective. Yale University Press, New Haven, 68-87. RUNGE, J., EISENBERG, J., SANGEN, M. (2006): Geomorphic evolution of the Ntem alluvial basin and physiogeographic evidence for Holocene environmental changes in the rain forest of SW Cameroon (Central Africa) - preliminary results. Z. Geomorph. N.F., Suppl. Bd. 145, 63-79. SERVANT, M. & SERVANT-VILDARY, S. (2000): Dynamique à long terme des écosystèmes forestiers intertropicaux. Publications issues du Symposium international « Dynamique à long terme des écosystèmes forestiers intertropicaux », Paris, 20-22 mars 1996. Paris, UNESCO, 1-434. WELDEAB, S., LEA, D.W., SCHNEIDER, R.R. & ANDERSEN, N. (2007): 155,000 years of West African monsoon ocean thermal evolution. Science, 316, 1303-1307.

  11. Integrated neural networks for monthly river flow estimation in arid inland basin of Northwest China

    NASA Astrophysics Data System (ADS)

    Huo, Zailin; Feng, Shaoyuan; Kang, Shaozhong; Huang, Guanhua; Wang, Fengxin; Guo, Ping

    2012-02-01

    Streamflow model including rainfall-runoff and river flow models play an important role in water resources management, especially in arid inland area. Traditional conceptual models have the disadvantage of requirement of spatial variation parameters about the physical characteristics of the catchments. To overcome this difficulty, in this study, several integrated Artificial Neural Networks (ANNs) were presented to estimate monthly river flow, and the models include the semi-distributed forms of ANNs that can explore spatial variation in hydrological process (such as rainfall distribution and evaporation distribution) and no requirement of physical characteristic parameters of the catchments. In an arid inland basin of Northwest, integrated ANNs were developed using hydrological and agricultural data, and its performance was compared with that of lumped ANN and local linear regression model (LLR). Results showed that the integrated ANNs perform well to estimate the monthly streamflow at outlet of mountain with Root Mean Square Error ( RMSE) of 0.36 × 10 7 m 3 and Relative Error ( RE) of 9%. Similarly, the integrated ANNs can also accurately estimate the monthly river flow downstream of the basin with RMSE of 0.35-0.38 × 10 7 m 3 and RE of 22-27%. When compared with integrated ANNs, the lumped ANN and LLR models have lower precision to simulate monthly streamflow in arid inland basin. Presented integrated ANN models retain the advantages of the semi-distributed models considering the heterogeneity and spatial variation of hydrological factors and the physical characteristics in the catchment, while taking advantage of the potential of ANNs as an effective tool in nonlinear mapping or functional relationship establishment. In contrast to traditional models either in the lumped ANN or in empirical regression forms, the new approach of integration of Artificial Neural Networks has shown great potential in streamflow modeling.

  12. Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

    1998-01-01

    Landsat thematic mapper data are used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation -the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

  13. Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

    1997-01-01

    Landsat Thematic Mapper data is used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation-the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

  14. Alluvial fan susceptibility to thermoerosion in a small arctic basin,Pangnirtung, NU

    NASA Astrophysics Data System (ADS)

    Gosselin, P.; Allard, M.; Falardeau-Marcoux, C.

    2011-12-01

    An exceptional rainstorm, high air temperature, thick snow cover and low soil permeability due to high permafrost table in early summer are some of the main causes that led to an extreme peak discharge of the Duval River, in Pangnirtung, Nunavut, on June 8, 2008. The 95 km2 catchment is located on mountainous terrain and the river flows in a steep channel down to a large Holocene alluvial fan on which the community is partially built. In a matter of several hours, an estimated volume of 91 000 m3 of sediments were eroded by the combined mechanical and thermal action of flowing water (thermoerosion). The bouldery main channel of the river was overdeepened by nearly 10 m while the permafrost river banks were undercut up to ~ 80 m laterally. The weight of the undercut bank eventually exceeded the strength of the permafrost and they collapsed, permanently damaging two bridges. As the Duval River flows through the community, the damage to the bridges resulted in limited access to some vital services such as distribution of drinking water and sewage transport. This event shows how climate change and, more specifically, the potential increase in the recurrence of extreme climatic events can trigger landscape hazards, raising safety concerns and infrastructure issues in northern communities. In order to help develop a more resilient community, this study focuses on understanding the process of thermal erosion and on assessing the potential risk of reoccurrence of a high magnitude fluvial event in Pangnirtung. The susceptibility to thermoerosion of the alluvial fan on which the river flows was determined by measuring the main characteristics of the permafrost (grain size, temperature profile, water and ice content) and of the Duval River (water temperature, discharge, channel slope). The unconsolidated sediments (silty-sand matrix till), the low ice-content and the relatively high permafrost temperature at the 12 m depth (-2.8 °C) are all factors promoting thermal erosion. However, the bouldery pavement of the river bed and at the foot of the river banks limits contact between water and permafrost and therefore inhibits heat transfer. The size of the boulders (over a meter in diameter) indicates that a particularly strong discharge is necessary to move them in order to expose permafrost to water. As the river is not gauged and precipitation data are sparse, estimates of the flow regime at the time of the thermal erosion event were derived from the assessment of the convective heat transport coefficient based on the size and rate of cutting of the thermal erosion notch as observed and photographed by community members.

  15. Potential incremental seepage losses in an alluvial channel in the Rio Grande Basin, New Mexico

    USGS Publications Warehouse

    Gold, R.L.

    1985-01-01

    A two-dimensional, digital, cross-sectional model was used to simulate seepage of water from an alluvial channel, which had the general characteristic of the Rio Grande channel, into the underlying alluvium within the reach from Cochiti Dam to Elephant Butte Reservoir. Seepage rates were determined for losing and gaining reaches, and reaches affected by pumping of ground water. The seepage rates were computed for stream surcharges (height of additional water applied on top of base flow) ranging from 0.5 foot to 3 feet and for application periods ranging from 1 to 100 days. The net seepage rates, which were nearly identical for each type of reach, ranged from 0.0 cubic foot per second per mile of channel length for a 0.5 foot surcharge applied for 1 day to 0.37 cubic foot per second per mile of channel length for a 3 feet surcharge applied for 100 days, followed by a 180 day seepage return flow from the aquifer. (USGS)

  16. Ichnofossils of the alluvial Willwood Formation (lower Eocene), Bighorn Basin, northwest Wyoming, U.S.A

    USGS Publications Warehouse

    Bown, T.M.; Kraus, M.J.

    1983-01-01

    The ichnofossil assemblage of the lower Eocene Willwood Formation consists of at least nine distinct endichnia that are preserved in full relief. Four forms (three ichnogenera and four ichnospecies) are new and represent fodinichnia and domichnia of oligochaete worms, an insect or spider, an unknown vertebrate (probably a mammal), and domichnia of an unidentified organism. Other potential trace makers of the ichnofauna include insects, mollusks, and decapods. In contrast to an Egyptian Oligocene fluvial ichnofauna produced largely by animals that burrowed in stream channel deposits, the Willwood assemblage is principally of flood-plain origin. Though the ichnofauna occurs in a variety of paleosol types, most of the fossils are restricted in distribution to specific sediment and soil types and, within paleosols, to specific identifiable horizons. This attribute will make them valuable indiced of paleoenvironment once they are better known in other ancient alluvial sequences. The environment suggested by the Willwood trace fossils (damp, but not wet soils with fluctuating water tables) is consistent with the warm temperate to subtropical (possibly monsoonal) conditions that are interpreted for the Willwood Formation by independent evidence of body fossils and paleopedology. ?? 1983.

  17. Ground water in the alluvial deposits of Cottonwood Creek Basin, Oklahoma

    USGS Publications Warehouse

    Stacy, B.L.

    1960-01-01

    Cottonwood Creek basin is a 377 square mile area in central Oklahoma. The rim of the basin has altitudes as high as 1,300 feet, and the mouth is at an altitude of 910. Deposits of Quaternary age consist of alluvium along the stream courses and high terrace deposits along the southern rim of the basin. The alluvium contains a high percentage of clay and silt, ranges in thickness from a few inches to 40 feet, and underlies about 36 square miles of the basin. Sandstone, siltstone, and shale of Permian age, which form the bedrock, consist of the Garber sandstone along the eastern edge, the Hennessey shale through the central part, and Flowerpot shale along the western edge. Replenishment of water in the alluvium is from precipitation, lateral seepage and runoff from adjoining areas, and infiltration from the stream channels during high flows. The major use of ground water in the alluvium is transpiration by cottonwood and willow trees. Virtually no water is withdrawn from the alluvium by wells. (available as photostat copy only)

  18. Seasonalizing mountain system recharge in semi-arid basins-climate change impacts.

    PubMed

    Ajami, Hoori; Meixner, Thomas; Dominguez, Francina; Hogan, James; Maddock, Thomas

    2012-01-01

    Climate variability and change impact groundwater resources by altering recharge rates. In semi-arid Basin and Range systems, this impact is likely to be most pronounced in mountain system recharge (MSR), a process which constitutes a significant component of recharge in these basins. Despite its importance, the physical processes that control MSR have not been fully investigated because of limited observations and the complexity of recharge processes in mountainous catchments. As a result, empirical equations, that provide a basin-wide estimate of mean annual recharge using mean annual precipitation, are often used to estimate MSR. Here North American Regional Reanalysis data are used to develop seasonal recharge estimates using ratios of seasonal (winter vs. summer) precipitation to seasonal actual or potential evapotranspiration. These seasonal recharge estimates compared favorably to seasonal MSR estimates using the fraction of winter vs. summer recharge determined from isotopic data in the Upper San Pedro River Basin, Arizona. Development of hydrologically based seasonal ratios enhanced seasonal recharge predictions and notably allows evaluation of MSR response to changes in seasonal precipitation and temperature because of climate variability and change using Global Climate Model (GCM) climate projections. Results show that prospective variability in MSR depends on GCM precipitation predictions and on higher temperature. Lower seasonal MSR rates projected for 2050-2099 are associated with decreases in summer precipitation and increases in winter temperature. Uncertainty in seasonal MSR predictions arises from the potential evapotranspiration estimation method, the GCM downscaling technique and the exclusion of snowmelt processes. PMID:22091994

  19. Timescales of alluvial fan development by precipitation on Mars

    NASA Astrophysics Data System (ADS)

    Armitage, John J.; Warner, Nicholas H.; Goddard, Kate; Gupta, Sanjeev

    2011-09-01

    Dozens of large, low-gradient alluvial fans are present within impact crater basins on the cratered highlands of Mars. The timescales and climate conditions that were required to generate such fans are unknown, but testable through our understanding of terrestrial hill slope erosion in the presence of precipitation. Previous estimates of fan formation time vary from years to millions of years. Here, we use an idealised physical model of 2-D catchment-fan evolution to present a framework within which the development of Martian alluvial fans should be considered. We simplify the erosional and depositional system so that there are only three variables: erodibility due to gravity, amount of water runoff due to precipitation, and catchment-fan boundary elevation. Within this framework, to generate large, low-gradient (<6°) alluvial fans on Mars requires significant periods of erosion due to runoff. We suggest two climate scenarios, either: (1) rates of precipitation that are similar to arid terrestrial climates over timescales of 107 to 108 yr or (2) a shorter duration of semiarid to temperate climate conditions over a period on the order of 106 yr. Hyper-arid conditions generate low-gradient alluvial fans under conditions of a topographically lowered fan-catchment boundary and only over timescales >108 yr if the substrate is extremely erodible relative to terrestrial examples.

  20. Interaction of a river with an alluvial basin aquifer: Stable isotopes, salinity and water budgets

    NASA Astrophysics Data System (ADS)

    Eastoe, Christopher J.; Hutchison, William R.; Hibbs, Barry J.; Hawley, John; Hogan, James F.

    2010-12-01

    SummaryDetailed sets of tracer data (isotopes, salinity) and the results of MODFLOW modeling of water budgets provide an unprecedented opportunity for comparing modeling with field data in the area where the Rio Grande enters the Hueco Bolson basin of Texas and Chihuahua. Water from the Rio Grande has recharged the Hueco Bolson aquifer to a depth of 300 m below the surface in the El Paso-Ciudad Juárez area, the depth of infiltration corresponding to the depth of ancestral Rio Grande fluvial sediments. Groundwater beneath the river exhibits complex isotope and salinity stratification. Post-dam (post -1916, type A) river water has infiltrated to depths up to 80 m. Pre-dam (type B) river water has infiltrated to 300 m depth near downtown El Paso, and has mixed with, or been displaced further downstream by high-salinity native Hueco Bolson groundwater (type C, present in the basin north of the river). Salinity and isotope boundaries do not correspond precisely. Isotope stratification corresponds to water residence time and (for type C) to degree of evaporation; the highest salinities are associated with the most evaporated water. Modeling of water budgets in the basin fill beneath the river predicts present-day mixing of water types B and C where changing rates of pumping have caused a reversal of groundwater flow direction between El Paso and Ciudad Juárez, and deep recharge of type B water under conditions prevailing in the 1960s.

  1. Controls of alluvial stratigraphy in the Upper Pennsylvania-Lower Permian Dunkard Basin

    SciTech Connect

    Dominic, D.F. )

    1991-08-01

    The Casselman, Pittsburgh, and Waynesburg formations exposed in northern West Virginia were deposited within a foreland basin adjacent to the Alleghenian fold and thrust belt. Sandstones were deposited in fluvial channels on an aggrading and prograding coastal plain. however, unlike mid-continental cyclothems, these channels were isolated from eustatic changes because previous delta progradation had blocked circulation between the local depositional basin and the larger mid-continental sea. Thus, eustatic changes had no direct or strong influence on Dunkard basin deposition, a conclusion supported by interbasinal correlation. Also, climate was largely stable during this interval. The evolution of channel properties, therefore, most likely reflects the influence of intrabasinal controls and possibly tectonism. Detailed correlation indicates that coeval channel belts were separated by about 50 km with an intervening area of slower subsidence and deposition. Quantitative reconstruction of bankfull hydraulics and geometry indicates that channels were of moderate sinuosity, were not braided, and were of two distinct sizes (average widths, 80 and 250 m, respectively). An overall decrease in discharge in the smaller channels throughout the studied interval may be attributed to a slowing of subsidence rates as the locus of sedimentation prograded beyond the northwestern margin of the Rome Trough or to thrustward migration of a forebulge following episodic thrusting. The increase in size and discharge of channels in the uppermost Waynesburg Formation is attributed to progradation of the upper fluvial-deltaic plain over the lower fluvial-deltaic plain, a progradation that may likewise have been promoted by thrusting.

  2. Clay sized fraction and powdered whole-rock X-ray analyses from alluvial basin deposits in central and southern New Mexico

    USGS Publications Warehouse

    Anderholm, S.K.

    1985-01-01

    As part of the study of the water quality and geochemistry of Southwest Alluvial Basins (SWAB) in parts of Colorado, New Mexico, and Texas, which is a Regional Aquifer-System Analysis (RASA) program, whole rock x-ray analysis and clay-size fraction mineralogy (x-ray) analysis of selected samples from alluvial basin deposits were done to investigate the types of minerals and clay types present in the aquifers. This was done to determine the plausible minerals and clay types in the aquifers that may be reacting with groundwater and affecting the water quality. The purpose of this report is only to present the whole rock x-ray and clay-fraction mineralogy data. Nineteen surface samples or samples from outcrop of Tertiary and Quaternary alluvial basin deposits in the central and southern Rio Grande rift were collected and analyzed. The analysis of the samples consisted of grain size analysis, and clay-size fraction mineralogy and semiquantitative analysis of the relative abundance of different clay mineral groups present. (USGS)

  3. Hydraulic processes on alluvial fans

    SciTech Connect

    French, R.H.

    1987-01-01

    Alluvial fans are among the most prominent landscape features in the American Southwest and throughout the semi-arid and arid regions of the world. The importance of developing a qualitative and quantitative understanding of the hydraulic processes which formed, and which continue to modify, these features derives from their rapid and significant development over the past four decades. As unplanned urban sprawl moved from valley floors onto alluvial fans, the serious damage incurred from infrequent flow events has dramatically increased. This book presents a discussion of our current and rapidly expanding knowledge of hydraulic processes on alluvial fans. It addresses the subject from a multidisciplinary viewpoint, acquainting the reader with geological principles pertinent to the analysis of hydraulic processes on alluvial fans.

  4. Conceptual model of the Great Basin carbonate and alluvial aquifer system

    USGS Publications Warehouse

    2011-01-01

    Prior to groundwater development, total groundwater discharge was estimated to be 4,200,000 acre-ft/yr with an uncertainty of ± 30 percent (± 1,300,000 acre-ft/yr). The two major components of discharge are evapotranspiration and springs. Estimated groundwater discharge to evapotranspiration and springs for predevelopment conditions was 1,800,000 acre-ft/yr and 990,000 acre-ft/yr, respectively. Other forms of discharge include discharge to basin-fill streams/lakes/reservoirs (660,000 acre-ft/yr), disc

  5. Sustainability of Water Resources in Arid Ecosystems: A View from Hei River Basin, China (Invited)

    NASA Astrophysics Data System (ADS)

    Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.

    2009-12-01

    The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex interactions and feedbacks between ecosystem functioning and water resources in an arid inland watershed. The findings will provide scientific basis for sustainable water resource management that maximizes the economic benefits without irreparably damaging the ecosystem.

  6. Evaluation of soil and water conservation measures in a semi-arid river basin in Tunisia using SWAT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Merguellil catchment (Central Tunisia) is a typical Mediterranean semi-arid basin which suffers from regular water shortage aggravated by current droughts. During the recent decades the continuous construction of small and large dams and Soil and Water Conservation Works (i.e. Contour ridges) ha...

  7. Simulation of Populus euphratica root uptake of groundwater in an arid woodland of the Ejina basin, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Ejina Basin is an extremely arid subwatershed in Northwest China. The predominant natural tree species in the area, Populus euphratica (P. euphratica), depends on groundwater for sustenance. In recent decades, groundwater overdraft and increased water diversions from the Heihe River caused wat...

  8. Estimation of alluvial-fill thickness in the Mimbres ground-water basin, New Mexico, from interpretation of isostatic residual gravity anomalies

    USGS Publications Warehouse

    Heywood, Charles E.

    2002-01-01

    The geologic structure of the Mimbres ground-water basin in southwest New Mexico is characterized by north- and northwest-trending structural subbasins. Sedimentation of Miocene and Pliocene age has filled and obscured the boundaries of these subbasins and formed poten- tially productive aquifers of varied thickness. The location and depth of the subbasins can be esti- mated from analysis of isostatic residual gravity anomalies. Density contrasts of various basement lithologies generate complex regional gravity trends, which are convolved with the gravity signal from the Miocene and Pliocene alluvial fill. An iterative scheme was used to separate these regional gravity trends from the alluvial-fill grav- ity signal, which was inverted with estimated depth-density relations to compute the thickness of the alluvial fill at 1-kilometer spacing. The thickness estimates were constrained by explor- atory drill-hole information, interpreted seismic- refraction profiles, and location of bedrock lithol- ogy from surficial geologic mapping. The result- ing map of alluvial-fill thickness suggests large areas of thin alluvium that separate deep structural subbasins.

  9. Coupled basin-scale water resource models for arid and semiarid regions

    NASA Astrophysics Data System (ADS)

    Winter, C.; Springer, E.; Costigan, K.; Fasel, P.; Mniewski, S.; Zyvoloski, G.

    2003-04-01

    Managers of semi-arid and arid water resources must allocate increasingly variable surface sources and limited groundwater resources to growing demands. This challenge is leading to a new generation of detailed computational models that link multiple interacting sources and demands. We will discuss a new computational model of arid region hydrology that we are parameterizing for the upper Rio Grande Basin of the United States. The model consists of linked components for the atmosphere (the Regional Atmospheric Modeling System, RAMS), surface hydrology (the Los Alamos Distributed Hydrologic System, LADHS), and groundwater (the Finite Element Heat and Mass code, FEHM), and the couplings between them. The model runs under the Parallel Application WorkSpace software developed at Los Alamos for applications running on large distributed memory computers. RAMS simulates regional meteorology coupled to global climate data on the one hand and land surface hydrology on the other. LADHS generates runoff by infiltration or saturation excess mechanisms, as well as interception, evapotranspiration, and snow accumulation and melt. FEHM simulates variably saturated flow and heat transport in three dimensions. A key issue is to increase the components’ spatial and temporal resolution to account for changes in topography and other rapidly changing variables that affect results such as soil moisture distribution or groundwater recharge. Thus, RAMS’ smallest grid is 5 km on a side, LADHS uses 100 m spacing, while FEHM concentrates processing on key volumes by means of an unstructured grid. Couplings within our model are based on new scaling methods that link groundwater-groundwater systems and streams to aquifers and we are developing evapotranspiration methods based on detailed calculations of latent heat and vegetative cover. Simulations of precipitation and soil moisture for the 1992-93 El Nino year will be used to demonstrate the approach and suggest further needs.

  10. Water quality in alluvial aquifers of the southern Rocky Mountains Physiographic Province, upper Colorado River basin, Colorado, 1997

    USGS Publications Warehouse

    Apodaca, Lori Estelle; Bails, Jeffrey B.

    2000-01-01

    Water-quality samples were collected in the summer of 1997 from 45 sites (43 wells and 2 springs) in selected alluvial aquifers throughout the Southern Rocky Mountains physiographic province of the Upper Colorado River Basin study unit as part of the U.S. Geological Survey National Water-Quality Assessment Program. The objective of this study was to assess the water-quality conditions in selected alluvial aquifers in the Southern Rocky Mountains physiographic province. Alluvial aquifers are productive aquifers in the Southern Rocky Mountains physiographic province and provide for easily developed wells. Water-quality samples were collected from areas where ground water is used predominantly for domestic or public water supply. Twenty-three of the 45 sites sampled were located in or near mining districts. No statistical differences were observed between the mining sites and sites not associated with mining activities for the majority of the constituents analyzed. Water samples were analyzed for major ions, nutrients, dissolved organic carbon, trace elements, radon-222, pesticides, volatile organic compounds, bacteria, and methylene blue active substances. In addition, field parameters consisting of water temperature, specific conductance, dissolved oxygen, pH, turbidity, and alkalinity were measured at all sites.Specific conductance for the ground-water sites ranged from 57 to 6,650 microsiemens per centimeter and had higher concentrations measured in areas such as the northwestern part of the study unit. Dissolved oxygen ranged from 0.1 to 6.0 mg/L (milligrams per liter) and had a median concentration of 2.9 mg/L. The pH field values ranged from 6.1 to 8.1; about 4 percent of the sites (2 of 45) had pH values outside the range of 6.5 to 8.5 and so did not meet the U.S. Environmental Protection Agency secondary maximum contaminant level standard for drinking water. About 5 percent (2 of 43) of the samples exceeded the U.S. Environmental Protection Agency recommended turbidity value of 5 nephelometric turbidity units; one of these samples was from a monitoring well. The U.S. Environmental Protection Agency secondary maximum contaminant levels for dissolved solids, sulfate, iron, and manganese were exceeded at some of the sites. Higher dissolved-solids concentrations were detected where sedimentary rocks are exposed, such as in the northwestern part of the Southern Rocky Mountains physiographic province. The dominant water compositions for the sites sampled are calcium, magnesium, and bicarbonate. However, sites in areas where sedimentary rocks are exposed and sites located in or near mining areas show more sulfate-dominated waters. Nutrient concentrations were less than the U.S. Environmental Protection Agency drinking-water standards. Only one site had a nitrate concentration greater than 3.0 mg/L, a level indicating possible influence from human activities. No significant differences among land-use/land-cover classifications (forest, rangeland, and urban) for drinking-water wells (42 sites) were identified for dissolved-solids, sulfate, nitrate, iron or manganese concentrations. Radon concentrations were higher in parts of the study unit where Precambrian rocks are exposed. All radon concentrations in ground water exceeded the previous U.S. Environmental Protection Agency proposed maximum contaminant level for drinking water, which has been withdrawn pending further review.Pesticide detections were at concentrations below the reporting limits and were too few to allow for comparison of the data. Eight volatile organic compounds were detected at six sites; all concentrations complied with U.S. Environmental Protection Agency drinking-water standards. Total coliform bacteria were detected at six sites, but no Escherichia coli (E. coli) was detected. Methylene blue active substances were detected at three sites at concentrations just above the reporting limit. Overall, the water quality in the Southern Rocky Mountains physiograph

  11. Modeling the Hydrological Response to Climate Change in an Arid Inland River Basin

    NASA Astrophysics Data System (ADS)

    Zheng, C.; Zhang, A.; Tian, Y.; Zheng, Y.; Liu, J.

    2014-12-01

    Located deep in the hinterlands of Eurasia, the Heihe River Basin (HRB) is an arid inland river basin in northwest China where the hydrologic regime responds sensitively to climate change. From the headwater region to terminal lakes, the HRB can be roughly divided into three sections, i.e., the upstream Qilian Mountains, the midstream oases and the downstream Gobi Desert. Runoff generated in the upstream mountainous terrains, dominated by climate variations, is the critical water resource for the whole river basin. With increasing intensification of climate change, there is an urgent need to understand future changes of water resources and water-related disasters to support regional water management. This study investigates the potential impact of climate change on hydrologic processes in the upper HRB for the future period of 2021~2150. Downscaled temperature and precipitation projections from six General Circulation Models under two emission scenarios (RCP4.5 and RCP8.5) are adopted to drive a commonly used flow model, Soil Water Assessment Tool (SWAT), for the upper HRB. The impacts of climate change on the total runoff and its components are quantified based on the future climate scenario analysis and the results of SWAT simulation. To understand how the climate change affects the availability and distribution of water resources in the middle and lower HRB where irrigated agriculture and ecosystem conservation compete for water resources, runoffs from the upper HRB are used as the boundary conditions for an integrated groundwater-surface water model based on the USGS GSFLOW for the middle and lower HRB. The integrated model assimilated multiple types of data including groundwater levels at monitoring wells, streamflow at gaging stations, and evapotranspiration (ET) derived from remote sensing data. The calibrated model was able to adequately reproduce the observed hydrological variables. The integrated model was then used to assess the potential response of the water cycle to both climate change and human activities, as well as the effectiveness of the current restoration practice. This study enhances our understanding of the complex interactions between future climate and watershed hydrology and provides the scientific basis for sustainable water resources management in arid inland river basins.

  12. Dynamics of Dissolved Inorganic Carbon in the Waterways of Antropogenically Influenced Closed Semi-Arid Basins

    NASA Astrophysics Data System (ADS)

    Jameel, M. Y.; Bowen, G. J.

    2014-12-01

    Inland aquatic carbon cycling is an important component of global carbon cycle and recent work has shown that anthropogenic activities can significantly alter the flux of terrestrial carbon through these systems to oceans and lakes. The study of dissolved carbon species in rivers provides detailed information about the natural and anthropogenic processing of carbon within a watershed. We measured water chemistry and stable isotope ratios (δ13C, δ18O, δ2H) of three major rivers (Bear, Jordan and Weber) seasonally, within the Great Salt Lake Basin to understand sources and processes governing the carbon cycling within the basin. Our preliminary data suggest strong correlation between the DIC concentration and land use/land cover for all the three waterways, with DIC increasing as the rivers flow through agricultural and urban regions. We also observed significant decrease in the DIC with the addition of fresh water from the tributaries which was most significant during the spring sampling. All the three rivers are super saturated in dissolved CO2 with respected to the atmospheric CO2 concentration, with pCO2 ranging from 1-5 times the atmospheric value and also showing strong seasonal variations. Coupling the pCO2 data with the isotopic value and concentration of DIC suggests that the variations within and among the rivers are manifestation of the different sources of DIC, further altered by in-situ processes such as organic respiration and photosynthesis. Our result suggest that human induced changes in land use and land cover have significantly altered the carbon budget of waterways of the Great Salt Lake Basin and carbon flux to the Great Salt Lake itself. Our future work will further quantify these changes, increasing our understanding of past, present and future changes in carbon cycling in closed semi-arid basins, and its importance in the global carbon cycle.

  13. Scaling up the Hydrologic Effects of Forest Thinning in Semi-Arid Basins of Arizona

    NASA Astrophysics Data System (ADS)

    Moreno, H. A.; White, D. D.; Gupta, H. V.; Vivoni, E. R.; Sampson, D. A.

    2013-12-01

    Understanding the effects of intensive forest thinning on the hydrology of semi-arid basins is critical to achieving water resources sustainability in the water limited Southwestern US, where disturbances to headwater catchment forests, can scale up to significant perturbations of the basin-scale water balance components. In northern Arizona, the Four Forest Restoration Initiative (4FRI) is being developed with the goal of restoring 2.4 million acres of Ponderosa pine along the Mogollon Rim. In this study, we examine the potential impacts of the 4FRI initiative on the hydrology of the Verde, Tonto and Salt rivers, which provide much of the water supply to the Phoenix Metropolitan Area. Long-term (20 year) simulations conducted using the tRIBS physically based spatially distributed model reveal shifts in the spatio-temporal regimes, and in the triggering processes, of runoff and integrated discharge as a response to feasible forest thinning scenarios. Specifically, our analysis suggests that alterations to the interception, evapotranspiration, recharge and snow processes within the forested areas will result in changes to long term water yield, and to extreme (peak and low flow) values. The results are helping local and regional water managers and policy makers to better understand the potential consequences of intensive forest removal and thereby influence decision making related to land use and the management of water resources.

  14. Sediment transport analysis at event scale in a semi-arid basin of Southern-Italy

    NASA Astrophysics Data System (ADS)

    Bisantino, T.; Gentile, F.; Milillo, F.; Romano, G.; Trisorio Liuzzi, G.

    2009-04-01

    Erosion at basin scale is a main issue in nowadays research since it plays a role of first level in sustainable management of natural resources (land and water). In particular, in arid and semi-arid regions natural vegetative cover is sparse and runoff events cause high rates of sediment transport, while long periods of drought can be observed. Several types of erosion phenomena affect the torrents in the north-western area of the Puglia Region (Southern-Italy) where flood events are characterised by a considerable amount of suspended solids. In this area the solid load was monitored until 1989 by the National Hydrographic Service using manual sampling. To accurately estimate the sediment transport during flood events and in order to improve the methodologies to assess and predict soil erosion, a watershed representative of the area (Carapelle torrent) was selected, where an experimental station was set up for the continuous measuring of suspended solids. The station is equipped with a dual function infrared sensor (turbidity/suspended solids), a remote data acquisition system, an electromechanical and an ultrasound stage meter. A laboratory test of the turbidity sensor was preliminary performed to evaluate the dual functionality of the instrument (turbidity and suspended sediment concentration) in relation to the variations of sediment concentration and grain size distribution. Successively a field calibration was carried out to determine the relationship between optical and gravimetric data and to check the housing device. Afterwards, the high temporal resolution data collected over a 3-years period (2007-2009) were used to analyze the sediment transport dynamics. The aim of the study is to investigate the relationships in unsteady flows between the sediment concentration and the discharge, and to analyze the relationships at event scale between the sediment budget and some hydrological variables, in order to select the model that best represents the local conditions.

  15. Sahra integrated modeling approach to address water resources management in semi-arid river basins

    SciTech Connect

    Springer, E. P.; Gupta, Hoshin V. ,; Brookshire, David S.; Liu, Y.

    2004-01-01

    Water resources decisions in the 21Sf Century that will affect allocation of water for economic and environmental will rely on simulations from integrated models of river basins. These models will not only couple natural systems such as surface and ground waters, but will include economic components that can assist in model assessments of river basins and bring the social dimension to the decision process. The National Science Foundation Science and Technology Center for Sustainability of semi-Arid Hydrology and Riparian Areas (SAHRA) has been developing integrated models to assess impacts of climate variability and land use change on water resources in semi-arid river basins. The objectives of this paper are to describe the SAHRA integrated modeling approach and to describe the linkage between social and natural sciences in these models. Water resources issues that arise from climate variability or land use change may require different resolution models to answer different questions. For example, a question related to streamflow may not need a high-resolution model whereas a question concerning the source and nature of a pollutant will. SAHRA has taken a multiresolution approach to integrated model development because one cannot anticipate the questions in advance, and the computational and data resources may not always be available or needed for the issue to be addressed. The coarsest resolution model is based on dynamic simulation of subwatersheds or river reaches. This model resolution has the advantage of simplicity and social factors are readily incorporated. Users can readily take this model (and they have) and examine the effects of various management strategies such as increased cost of water. The medium resolution model is grid based and uses variable grid cells of 1-12 km. The surface hydrology is more physically based using basic equations for energy and water balance terms, and modules are being incorporated that will simulate engineering components such as reservoirs or irrigation diversions and economic features such as variable demand. The fine resolution model is viewed as a tool to examine basin response using best available process models. The fine resolution model operates on a grid cell size of 100 m or less, which is consistent with the scale that our process knowledge has developed. The fine resolution model couples atmosphere, surface water and groundwater modules using high performance computing. The medium and fine resolution models are not expected at this time to be operated by users as opposed to the coarse resolution model. One of the objectives of the SAHRA integrated modeling task is to present results in a manner that can be used by those making decisions. The application of these models within SAHRA is driven by a scenario analysis and a place location. The place is the Rio Grande from its headwaters in Colorado to the New Mexico-Texas border. This provides a focus for model development and an attempt to see how the results from the various models relate. The scenario selected by SAHRA is the impact of a 1950's style drought using 1990's population and land use on Rio Grande water resources including surface and groundwater. The same climate variables will be used to drive all three models so that comparison will be based on how the three resolutions partition and route water through the river basin. Aspects of this scenario will be discussed and initial model simulation will be presented. The issue of linking economic modules into the modeling effort will be discussed and the importance of feedback from the social and economic modules to the natural science modules will be reviewed.

  16. Geohydrology, water quality, and preliminary simulations of ground-water flow of the alluvial aquifer in the Upper Black Squirrel Creek basin, El Paso County, Colorado

    USGS Publications Warehouse

    Buckles, D.R.; Watts, K.R.

    1988-01-01

    The upper Black Squirrel Creek basin in eastern El Paso County, Colorado, is underlain by an alluvial aquifer and four bedrock aquifers. Groundwater pumpage from the alluvial aquifer has increased since the mid-1950's, and water level declines have been substantial; the bedrock aquifers virtually are undeveloped. Groundwater pumpage for domestic, stock, agricultural, and municipal uses have exceeded recharge for the past 25 years. The present extent of the effect of pumpage on the alluvial aquifer was evaluated, and a groundwater flow model was used to simulate the future effect of continued pumpage on the aquifer. Measured water level declines from 1974 through 1984 were as much as 30 ft in an area north of Ellicott, Colorado. On the basis of the simulations, water level declines from October 1984 to April 1999 north of Ellicott might be as much as 20 to 30 ft and as much as 1 to 10 ft in most of the aquifer. The groundwater flow models provided a means of evaluating the importance of groundwater evapotranspiration at various stages of aquifer development. Simulated groundwater evapotranspiration was about 43% of the outflow from the aquifer during predevelopment stages but was less than 3% of the outflow from the aquifer during late-development stages. Analyses of 36 groundwater samples collected during 1984 indicated that concentrations of dissolved nitrite plus nitrate as nitrogen generally were large. Samples from 5 of the 36 wells had concentrations of dissolved nitrite plus nitrate as nitrogen that exceeded drinking water standards. Water from the alluvial aquifer generally is of suitable quality for most uses. (USGS)

  17. [Transpiration of Hedysarum scoparium in arid desert region of Shiyang River basin, Gansu Province].

    PubMed

    Xia, Gui-min; Kang, Shao-zhong; Du, Tai-sheng; Yang, Xiu-ying; Zhang, Ji

    2007-06-01

    By using heat pulse technique, an investigation on the transpiration of Hedysarum scoparium was conducted in the arid desert region of Shiyang River basin, Gansu Province. The results indicated that with increasing inserted depth of probe, the sap flow velocity in H. scoparium xylem had a trend from high to low. In the taproot with smaller diameter, the average sap flow velocity at different positions was faster, and the change range was bigger. Among the taproots with different diameters, there existed a larger difference in the magnitude of sap flux, but the change trend was similar, i. e., smaller at nighttime and larger at daytime, and showing a multi-peak curve. A linear correlation was observed between the diurnal sap flux and the reference crop evapotranspiration, and the transpiration mainly occurred during the period from June to September, occupying 79.04% of the total annual transpiration. The diurnal sap flux of H. scoparium at its later growth period had significant correlation with the moisture content in 0-50 cm sand layer, but no correlations with that in other sand layers. The effects of main meteorological factors on the sap flux of H. scoparium were in the sequence of air temperature > vapor pressure difference > wind speed. PMID:17763715

  18. Drainage Basin Erosion Rates Along the Death Valley Fault Zone, California From In-Situ Cosmogenic 14C in Alluvial Sediment: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Frankel, K. L.; Pigati, J. S.; Hoeft, J. S.; Lifton, N. A.; Dolan, J. F.

    2004-12-01

    Catchment-wide erosion rates and drainage basin evolution are poorly understood processes in arid and hyper-arid climates. We collected samples from two small catchments in Death Valley, CA to determine basin-wide erosion rates using in-situ cosmogenic 14C to help understand drainage development in a hyper-arid setting. Death Valley is a tectonically active pull-apart system with a normal fault-bounded basin in the center and strike-slip faults to the north and south. On average, the area receives < 5 cm of precipitation per year. Two basins were sampled from different parts of the fault zone; one along the normal fault-bounded segment in the Black Mountains and one from the southern strike-slip segment in the Owlshead Mountains. Topography along the dip-slip segment of the fault zone in the Black Mountains is youthful with steep, high relief catchments, triangular facets, and young fault scarps at the base of the range. Drainage basins in the Black Mountains have high ratios of basin excavated volume to planimetric area and high first-order stream gradients. Additionally, basins formed along the normal fault-bounded segment typically have large, 10-20 m high knickpoints and highly convex channel profiles. In contrast, the Owlshead Mountains are relatively low relief, and appear to be in a state of topographic decay. Samples were collected above and below a ˜20 m high knickpoint in the Badwater catchment, above and below a smaller (5 m high) knickzone in the Owlshead Mountains, and at the mouths of both catchments. In-situ 14C can be used to determine erosion rates in rapidly denuding areas that are integrated over a period of several thousand years. We are particularly interested in post-last glacial maximum erosion rates, which could be a function of climate change and the drying up of glacial Lake Manly, relative base-level fall resulting from recent movement on the fault zone, or a combination of both. Previous studies have shown that climate change since the last glacial maximum appears to have had little or no effect on erosion rates in eastern California. Because of this, drainage basin erosion rates may express a link between ground-rupturing earthquake activity on the Death Valley fault zone and denudation. The catchment-wide erosion rates may also help characterize fault zone segmentation, in conjunction with paleoseismologic, slip rate, and topographic metrics data.

  19. How Widely Applicable is River Basin Management? An Analysis of Wastewater Management in an Arid Transboundary Case

    NASA Astrophysics Data System (ADS)

    Dombrowsky, Ines; Almog, Ram; Becker, Nir; Feitelson, Eran; Klawitter, Simone; Lindemann, Stefan; Mutlak, Natalie

    2010-05-01

    The basin scale has been promoted universally as the optimal management unit that allows for the internalization of all external effects caused by multiple water uses. However, the basin scale has been put forward largely on the basis of experience in temperate zones. Hence whether the basin scale is the best scale for management in other settings remains questionable. To address these questions this paper analyzes the economic viability and the political feasibility of alternative management options in the Kidron/Wadi Nar region. The Kidron/Wadi Nar is a small basin in which wastewater from eastern Jerusalem flows through the desert to the Dead Sea. Various options for managing these wastewater flows were analyzed ex ante on the basis of both a cost benefit and a multi-criteria analysis. The paper finds that due to economies of scale, a pure basin approach is not desirable from a physical and economic perspective. Furthermore, in terms of political feasibility, it seems that the option which prompts the fewest objections from influential stakeholder groups in the two entities under the current asymmetrical political setting is not a basin solution either, but a two plant solution based on an outsourcing arrangement. These findings imply that the river basin management approach can not be considered the best management approach for the arid transboundary case at hand, and hence is not unequivocally universally applicable.

  20. How widely applicable is river basin management? An analysis of wastewater management in an arid transboundary case.

    PubMed

    Dombrowsky, Ines; Almog, Ram; Becker, Nir; Feitelson, Eran; Klawitter, Simone; Lindemann, Stefan; Mutlak, Natalie

    2010-05-01

    The basin scale has been promoted universally as the optimal management unit that allows for the internalization of all external effects caused by multiple water uses. However, the basin scale has been put forward largely on the basis of experience in temperate zones. Hence whether the basin scale is the best scale for management in other settings remains questionable. To address these questions this paper analyzes the economic viability and the political feasibility of alternative management options in the Kidron/Wadi Nar region. The Kidron/Wadi Nar is a small basin in which wastewater from eastern Jerusalem flows through the desert to the Dead Sea. Various options for managing these wastewater flows were analyzed ex ante on the basis of both a cost benefit and a multi-criteria analysis. The paper finds that due to economies of scale, a pure basin approach is not desirable from a physical and economic perspective. Furthermore, in terms of political feasibility, it seems that the option which prompts the fewest objections from influential stakeholder groups in the two entities under the current asymmetrical political setting is not a basin solution either, but a two plant solution based on an outsourcing arrangement. These findings imply that the river basin management approach can not be considered the best management approach for the arid transboundary case at hand, and hence is not unequivocally universally applicable. PMID:20383707

  1. The Italian Project S2 - Task 4:Near-fault earthquake ground motion simulation in the Sulmona alluvial basin

    NASA Astrophysics Data System (ADS)

    Stupazzini, M.; Smerzini, C.; Cauzzi, C.; Faccioli, E.; Galadini, F.; Gori, S.

    2009-04-01

    Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http://nuovoprogettoesse2.stru.polimi.it/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et al., 2003). In particular, while "the OpenSHA collaboration model envisions scientists developing their own attenuation relationships and earthquake rupture forecasts, which they will deploy and maintain in their own systems", the main purpose of S2 project is to provide a flexible computational tool for SHA, primarily suited for the needs of DPC, which not necessarily are scientific needs. Within S2, a crucial issue is to make alternative approaches available to quantify the ground motion, with emphasis on the near field region. The SHA architecture envisaged will allow for the use of ground motion descriptions other than those yielded by empirical attenuation equations, for instance user generated motions provided by deterministic source and wave propagation simulations. In this contribution, after a brief presentation of Project S2, we intend to illustrate some preliminary 3D scenario simulations performed in the alluvial basin of Sulmona (Central Italy), as an example of the type of descriptions that can be handled in the future SHA architecture. In detail, we selected some seismogenic sources (from the DISS database), believed to be responsible for a number of destructive historical earthquakes, and derive from them a family of simplified geometrical and mechanical source models spanning across a reasonable range of parameters, so that the extent of the main uncertainties can be covered. Then, purely deterministic (for frequencies < 2Hz) and hybrid deterministic- stochastic source and propagation simulations are carried out for different fault rupture scenarios (but including important features such as the dominant near-surface geology), and the results in terms of representative ground motion parameters appropriately enveloped. The fully 3D problem is solved using the Spectral Element (SE) method, extensively published by Faccioli and his co-workers, and Quarteroni and co- workers, starting from 1996, and the computational code GeoELSE (Stupazzini et al., 2009; http://GeoELSE.stru.polimi.it/). Finally, numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near-fault regions elsewhere. Based on the results of this work, the unfavorable interaction between fault rupture, radiation mechanism and complex geological conditions may give rise to large values of peak ground velocity (exceeding 1 m/s) even in low-to-moderate seismicity areas, and therefore increase considerably the level of seismic risk, especially in highly populated and industrially active regions, such as the Central Italy. Faccioli E., Maggio F., Paolucci R. and Quarteroni A. (1997),2D and 3D elastic wave propagation by a pseudo-spectral domain decomposition method, Journal of Seismology, 1, 237-251. Field, E.H., T.H. Jordan, and C.A. Cornell (2003), OpenSHA: A Developing Community-Modeling Environment for Seismic Hazard Analysis, Seism. Res. Lett. 74, 406-419. Stupazzini M., R. Paolucci, H. Igel (2009), Near-fault earthquake ground motion simulation in the Grenoble Valley by a high-performance spectral element code, accepted for publication in Bull. of the Seism. Soc. of America.

  2. Well-log signatures of alluvial-lacustrine reservoirs and source rocks, Lagoa-Feia Formations, Lower Cretaceous, Campos Basin, offshore Brazil

    SciTech Connect

    Abrahao, D.; Warme, J.E.

    1988-01-01

    The Campos basin is situated in offshore southeastern Brazil. The Lagoa Feia is the basal formation in the stratigraphic sequence of the basin, and was deposited during rifting in an evolving complex of lakes of different sizes and chemical characteristics, overlying and closely associated with rift volcanism. The stratigraphic sequence is dominated by lacustrine limestones and shales (some of them organic-rich), and volcaniclastic conglomerates deposited on alluvial fans. The sequence is capped by marine evaporites. In the Lagoa Feia Formation, complex lithologies make reservoirs and source rocks unsuitable for conventional well-log interpretation. To solve this problem, cores were studied and the observed characteristics related to log responses. The results have been extended through the entire basin for other wells where those facies were not cored. The reservoir facies in the Lagoa Feia Formation are restricted to levels of pure pelecypod shells (''coquinas''). Resistivity, sonic, neutron, density, and gamma-ray logs were used in this work to show how petrophysical properties are derived for the unconventional reservoirs existing in this formation. The same suite of logs was used to develop methods to define geochemical characteristics where source rock data are sparse in the organic-rich lacustrine shales of the Lagoa Feia Formation. These shales are the main source rocks for all the oil discovered to date in the Campos basin.

  3. Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA.

    PubMed

    Arkle, Robert S; Pilliod, David S

    2015-09-01

    A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species' range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change, factors which threaten local or regional persistence. PMID:26380699

  4. Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA

    PubMed Central

    Arkle, Robert S; Pilliod, David S

    2015-01-01

    A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change, factors which threaten local or regional persistence. PMID:26380699

  5. The organic and mineral matter contents in deposits infilling floodplain basins: Holocene alluviation record from the K?odnica and Osob?oga river valleys, southern Poland

    NASA Astrophysics Data System (ADS)

    Wójcicki, K. J.; Marynowski, L.

    2012-07-01

    The work examines the timing and environmental conditions of floodplain sedimentation in the valleys of the upland K?odnica and piedmont Osob?oga rivers in the Upper Odra River basin. A distribution of 52 14C-ages shows relatively high floodplain sedimentation at the Late Glacial-Holocene transition, more stable floodplain environments since the Early (in the K?odnica Valley) and Middle Holocene (in the Osob?oga Valley) and a gradual increase in floodplain deposition in the Late Holocene (since < 3.4 kyr BP). Organic matter [OM] and mineral matter [MM] fluctuations were correlated with variables responsible for the activation of erosion (i.e. vegetation changes, human impact and hydrological events) as well as factors affecting the local record of sedimentation (i.e. valley morphology, hydrologic conditions and episodes of local erosion). A clear relationship is shown between an increase in alluviation and climate- or human-induced extension of unforested areas. The deposition of mineral-rich sediments increases rapidly during periods characterized by non-arboreal pollen values exceeding approximately 8% in pollen diagrams. On the other hand, the results obtained do not confirm significant interactions between Holocene changes in forest composition and alluviation. Despite the settlement of agrarian groups, the sedimentary record of human activity in the Osob?oga catchment is very poor during the Neolithic and early Bronze Age. A large-scale alluviation of the Osob?oga and K?odnica valleys was initiated during the settlement of people of the Lusatian culture from the middle Bronze Age and escalated in the early Middle Ages and Modern Times. The deposition of products of soil erosion was limited to between ca. 1.9-1.2 kyr BP, probably due to demographic regression during the Migration Period. Comparison of OM/MM fluctuations with phases of increased fluvial activity does not show a relationship between Holocene wetter phases and catchment sediment yield. Sedimentary episodes in the Upper Odra basin also show a low degree of correlation with the probability density curve of the 14C-ages. The results obtained in the K?odnica and Osob?oga valleys indicate a strong to moderate correlation between the spatial distribution of the study sites and the origin of MM-rich deposits, but a weak correlation between the spatial distribution of the study sites and TOC content. Such a pattern suggests that OM/MM fluctuations relate predominantly to the changes in sediment yield, although morphological conditions have a significant impact on the capture potential of sedimentary basins during phases of alluviation. Additionally, high OM content is not a simple function of an increase in wetness of the sedimentary environment. On the other hand, hydrologically-conditioned hiatuses as well as erosion episodes impoverish the sedimentary record, complicating the consideration on the geochronology of deposits and making it difficult to calculate reliable accumulation rates. However, they do not reduce the value of OM/MM fluctuations as an indicator of alluviation events for a preserved series of sediments.

  6. Palaeoenvironments and palaeotectonics of the arid to hyperarid intracontinental latest Permian- late Triassic Solway basin (U.K.)

    NASA Astrophysics Data System (ADS)

    Brookfield, Michael E.

    2008-10-01

    The late Permian to late Triassic sediments of the Solway Basin consist of an originally flat-lying, laterally persistent and consistent succession of mature, dominantly fine-grained red clastics laid down in part of a very large intracontinental basin. The complete absence of body or trace fossils or palaeosols indicates a very arid (hyperarid) depositional environment for most of the sediments. At the base of the succession, thin regolith breccias and sandstones rest unconformably on basement and early Permian rift clastics. Overlying gypsiferous red silty mudstones, very fine sandstones and thick gypsum were deposited in either a playa lake or in a hypersaline estuary, and their margins. These pass upwards into thick-bedded, multi-storied, fine- to very fine-grained red quartzo-felspathic and sublithic arenites in which even medium sand is rare despite channels with clay pebbles up to 30 cm in diameter. Above, thick trough cross-bedded and parallel laminated fine-grained aeolian sandstones (deposited in extensive barchanoid dune complexes) pass up into very thick, multicoloured mudstones, and gypsum deposited in marginal marine or lacustrine sabkha environments. The latter pass up into marine Lower Jurassic shales and limestones. Thirteen non-marine clastic lithofacies are arranged into five main lithofacies associations whose facies architecture is reconstructed where possible by analysis of large exposures. The five associations can be compared with the desert pavement, arid ephemeral stream, sabkha, saline lake and aeolian sand dune environments of the arid to hyperarid areas of existing intracontinental basins such as Lake Eyre and Lake Chad. The accommodation space in such basins is controlled by gradual tectonic subsidence moderated by large fluctuations in shallow lake extent (caused by climatic change and local variation) and this promotes a large-scale layer-cake stratigraphy as exemplified in the Solway basin. Here, the dominant fine-grained mature sandstones above the local basal reg breccias suggest water-reworking of wind-transported sediment, as in the northern part of the Lake Chad basin. Growth faulting occurs in places in the Solway basin, caused by underlying evaporite movement, but these faults did not significantly affect pre-late Triassic sedimentation and did not expose pre-Permian units above the basal breccias. There is no evidence of post-early Permian rifting anywhere during deposition of the late Permian to middle Triassic British succession although the succession is often interpreted with a rift-basin model. The arid to hyperarid palaeoclimate changed little during deposition of the Solway basin succession, in contrast to Lakes Eyre and Chad: and this is attributed to tectonic and palaeolatitude stability. Unlike the later Mesozoic- Cenozoic, only limited plate movements took place during the Triassic in western Europe, palaeolatitude changed little, and the Solway Basin remained in the northern latitudinal desert belt from early to mid-Triassic times. However, the influence of the early Triassic impoverished biota on environmental interpretations needs further study.

  7. Regional groundwater-flow model of the Redwall-Muav, Coconino, and alluvial basin aquifer systems of northern and central Arizona

    USGS Publications Warehouse

    Pool, D.R.; Blasch, Kyle W.; Callegary, James B.; Leake, Stanley A.; Graser, Leslie F.

    2011-01-01

    A numerical flow model (MODFLOW) of the groundwater flow system in the primary aquifers in northern Arizona was developed to simulate interactions between the aquifers, perennial streams, and springs for predevelopment and transient conditions during 1910 through 2005. Simulated aquifers include the Redwall-Muav, Coconino, and basin-fill aquifers. Perennial stream reaches and springs that derive base flow from the aquifers were simulated, including the Colorado River, Little Colorado River, Salt River, Verde River, and perennial reaches of tributary streams. Simulated major springs include Blue Spring, Del Rio Springs, Havasu Springs, Verde River headwater springs, several springs that discharge adjacent to major Verde River tributaries, and many springs that discharge to the Colorado River. Estimates of aquifer hydraulic properties and groundwater budgets were developed from published reports and groundwater-flow models. Spatial extents of aquifers and confining units were developed from geologic data, geophysical models, a groundwater-flow model for the Prescott Active Management Area, drill logs, geologic logs, and geophysical logs. Spatial and temporal distributions of natural recharge were developed by using a water-balance model that estimates recharge from direct infiltration. Additional natural recharge from ephemeral channel infiltration was simulated in alluvial basins. Recharge at wastewater treatment facilities and incidental recharge at agricultural fields and golf courses were also simulated. Estimates of predevelopment rates of groundwater discharge to streams, springs, and evapotranspiration by phreatophytes were derived from previous reports and on the basis of streamflow records at gages. Annual estimates of groundwater withdrawals for agriculture, municipal, industrial, and domestic uses were developed from several sources, including reported withdrawals for nonexempt wells, estimated crop requirements for agricultural wells, and estimated per capita water use for exempt wells. Accuracy of the simulated groundwater-flow system was evaluated by using observational control from water levels in wells, estimates of base flow from streamflow records, and estimates of spring discharge. Major results from the simulations include the importance of variations in recharge rates throughout the study area and recharge along ephemeral and losing stream reaches in alluvial basins. Insights about the groundwater-flow systems in individual basins include the hydrologic influence of geologic structures in some areas and that stream-aquifer interactions along the lower part of the Little Colorado River are an effective control on water level distributions throughout the Little Colorado River Plateau basin. Better information on several aspects of the groundwater flow system are needed to reduce uncertainty of the simulated system. Many areas lack documentation of the response of the groundwater system to changes in withdrawals and recharge. Data needed to define groundwater flow between vertically adjacent water-bearing units is lacking in many areas. Distributions of recharge along losing stream reaches are poorly defined. Extents of aquifers and alluvial lithologies are poorly defined in parts of the Big Chino and Verde Valley sub-basins. Aquifer storage properties are poorly defined throughout most of the study area. Little data exist to define the hydrologic importance of geologic structures such as faults and fractures. Discharge of regional groundwater flow to the Verde River is difficult to identify in the Verde Valley sub-basin because of unknown contributions from deep percolation of excess surface water irrigation.

  8. Lower Eocene alluvial paleosols (Willwood Formation, Northwest Wyoming, U.S.A.) and their significance for paleoecology, paleoclimatology, and basin analysis

    USGS Publications Warehouse

    Bown, T.M.; Kraus, M.J.

    1981-01-01

    The lower Eocene Willwood Formation of northwest Wyoming is a 700 m thick accumulation of alluvial floodplain and channel mudstones and sandstones, nearly all of which show paleopedogenic modifications. Pedogenesis of Willwood sandstones is indicated by taproot and vertebrate and invertebrate bioturbation, early local cementation by calcium carbonate, and thin illuviation cutans on clastic grains. Pedogenesis in Willwood mudstones is indicated by plant bioturbation, insect and other invertebrate burrow casts and lebensspuren; free iron, aluminum, and manganese mobilization, including hydromorphic gleying; sesquioxide and calcareous glaebule formation in lower parts of the solum; presence of clay-rich and organic carbon-rich zones; and well differentiated epipedons and albic and spodic horizons. Probable A horizons are also locally well developed. Occurrence of variegated paleosol units in thick floodplain mudstone deposits and their association with thin, lenticular, and unconnected fluvial sandstones in the Willwood Formation of the central and southeast Bighorn Basin suggest that these soils formed during times of rapid sediment accumulation. The tabular geometry and lateral persistence of soil units as well as the absence of catenization indicate that Willwood floodplains were broad and essentially featureless. All Willwood paleosols were developed on alluvial parent materials and are complex in that B horizons of younger paleosols were commonly superimposed upon and mask properties of suspected A and B horizons of the next older paleosols. The soils appear to be wet varieties of the Spodosol and Entisol groups (aquods and ferrods, and aquents, respectively), though thick, superposed and less mottled red, purple, and yellow paleosols resemble some ultisols. Most Willwood paleosols resemble warm temperate to subtropical alluvial soils that form today under alternating wet and dry conditions and (or) fluctuating water tables. The up-section decrease in frequency of gley mottles, increase in numerical proportion and thickness of red versus orange coloration, and increase in abundance of calcrete glaebules indicate better drained soils and probably drier climate in late Willwood time. This drying is believed to be related to creation of rain shadows and spacing of rainfall (but not necessarily decrease in absolute rainfall) due to progressive tectonic structural elevation of the mountainous margins of the Bighorn Basin. ?? 1981.

  9. Mapping Ecological Processes and Ecosystem Services for Prioritizing Restoration Efforts in a Semi-arid Mediterranean River Basin

    NASA Astrophysics Data System (ADS)

    Trabucchi, Mattia; O'Farrell, Patrick J.; Notivol, Eduardo; Comín, Francisco A.

    2014-06-01

    Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin.

  10. Mapping ecological processes and ecosystem services for prioritizing restoration efforts in a semi-arid Mediterranean river basin.

    PubMed

    Trabucchi, Mattia; O'Farrell, Patrick J; Notivol, Eduardo; Comín, Francisco A

    2014-06-01

    Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin. PMID:24728487

  11. Late Pleistocene to Holocene alluvial tableland formation in an intra-mountainous basin in a tectonically active mountain belt ― A case study in the Puli Basin, central Taiwan

    NASA Astrophysics Data System (ADS)

    Tseng, Chia-Han; Lüthgens, Christopher; Tsukamoto, Sumiko; Reimann, Tony; Frechen, Manfred; Böse, Margot

    2016-01-01

    The morphology in Taiwan is a product of high tectonic activity at the convergent margin and East Asian monsoon climate. Tablelands are prominent geomorphic features in the Puli Basin in central Taiwan. These tablelands provide an archive to understand links between past climatic evolution and tectonic events resulting in the formation of the present-day landforms. To establish a geochronological framework for the alluvium underlying the tablelands in the Puli Basin, optically stimulated luminescence dating was applied to obtain burial ages. The numerical data indicate an accumulation phase of alluvial fans in the Late Pleistocene to Early Holocene transition. The study area in the Taomi River catchment, an obvious longer precursor of the Taomi River, originating from west of the Yuchih Basin, transported the sediments forming the present-day southern tablelands. During the Pleistocene-Holocene transition, the climate changed to wetter and warmer conditions, so that slope processes might have changed and an increasing transport in the fluvial system was stimulated. Fluvial and fan terraces in other river catchments in Taiwan also indicate a period of increased fluvial transport and deposition. A geomorphic evolution model in the Puli Basin is reconstructed on the basis of the chronological framework and of sedimentological features. Fluvial processes controlled by climatic change and accompanied by tectonic activities have created the diverse topography in the Puli Basin.

  12. Effect of seasonal flooding cycle on litterfall production in alluvial rainforest on the middle Xingu River (Amazon basin, Brazil).

    PubMed

    Camargo, M; Giarrizzo, T; Jesus, Ajs

    2015-08-01

    The assumption for this study was that litterfall in floodplain environments of the middle Xingu river follows a pattern of seasonal variation. According to this view, litterfall production (total and fractions) was estimated in four alluvial rainforest sites on the middle Xingu River over an annual cycle, and examined the effect of seasonal flooding cycle. The sites included two marginal flooded forests of insular lakes (Ilha Grande and Pimentel) and two flooded forests on the banks of the Xingu itself (Boa Esperança and Arroz Cru). Total litterfall correlated with rainfall and river levels, but whereas the leaf and fruit fractions followed this general pattern, the flower fraction presented an inverse pattern, peaking in the dry season. The litterfall patterns recorded in the present study were consistent with those recorded at other Amazonian sites, and in some other tropical ecosystems. PMID:26691098

  13. A tectonically controlled alluvial fan which developed into a marine fan-delta at a complex triple junction: Miocene Gildirli Formation of the Adana Basin, Turkey

    NASA Astrophysics Data System (ADS)

    Görür, Naci

    1992-12-01

    The sediments of the Gildirli Formation in the Karaisali embayment of the Adana Basin, southern Turkey, records the evolution, under tectonic control at a complex triple junction, of an alluvial fan into a fan-delta during a rapid Early Miocene transgression. The alluvial fan is represented by the lower part of the formation (Çakmak Member) and is characterized by an internal architecture, recording an overall progradation of the coarse proximal fan conglomerates over distal fine-grained sediments. The conglomerates contain mostly Upper Cretaceous limestone clasts of various sizes derived from the faulted mountain front of the Taurus range where this limestone is widely exposed. This active mountain front delimited the Karaisah embayment to the north and provided, during the fault activity, abundant coarse clasts to this area throughout the deposition of both the alluvial fan and the overlying fan-delta sediments. The production of fine detritus during the faulting was very limited and therefore this source contributed little fine grain detritus to the sediments. Provenance studies indicate that the fine clastics in the Gildirli Formation were carried by streams during periods of active faulting and also during periods of tectonic quiescence from a far-distant source in the hinterlands of the Taurus Mountains. The recurrent activity along the northern boundary-fault resulted in the intercalation of these fine clastics with the predominant coarse sediments in this formation. When the study area was flooded from the south by a rapidly deepening Early Miocene sea, the accumulation of all these sediments took place in a fan-delta environment. The fan-delta sediments constitute the upper parts of the Gildirli Formation (Kabalaktepe Member) and display an inverse facies pattern in which foreset beds overlie topsets and hence an upward-fining and deepening sequence. This deviation from a genetic upward-coarsening sequence of a typical marine delta was perhaps the result of a rapid relative rise in sea-level, due to tectonically induced subsidence of the area possibly coupled with a short-term global sea-level rise in the Burdigalian.

  14. Volcaniclastic-alluvial sedimentation interaction in the Tordillo Fm., Upper Jurassic, Neuquén Basin (Argentina): An approach for paleogeographic and tectonic development.

    NASA Astrophysics Data System (ADS)

    López-Gómez, José; Martín-Chivelet, Javier; Lago, Marceliano; Palma, Ricardo; Kietzmann, Diego

    2010-05-01

    The Neuquén Basin is a Mesozoic back-arc basin located in central-western Argentina and eastern Chile and today incorporated into the Andean retro-arc foreland basin. The Upper Jurassic Tordillo Formation at the northern Neuquén Basin, Argentina, was developed during a generalized subsidence with still clear fault influence that followed a Late Triassic-Early Jurassic rifting phase. Although this formation comprises a multi-stage suit of predominantely alluvial sediments that is heterolithic in nature, aeolian and volcaniclastic sediments are also present. Volcaniclastic sediments are mainly andesitic in composition where subaerial pyroclastic flows and fallout deposits (and their remobilised sediments) are common. They are interbedded with fluvial braided and meandering sediments showing a clear interdependence. Sediment supply in the Neuquén Basin was markedly influenced by the uplift and later subsidence controlled by the magmatic activity. Explosive volcanic eruptions coupled with sporadic high rainfall events led to transportation and accumulation of large quantities of coarse volcaniclastic debris, including dm-scale blocks. Defined volcaniclastic facies include pyroclastic and epiclastic deposits of both primary and secondary origin. Pyroclastic deposits include flow and fall deposits, this latter with bombs and lapilli deposits. They are massive or show sequences. These latter normally show erosive base and are represented by 0.4 to 0.8m in thickness of reverse, normal and normal-reverse grading in which traction structures as lamination and cross-bedding appear. Associated flame, load and scour structures are also common at the top of the sequences. All of these deposits are related to a range that varies from subaerial to shallow water in origin. Some of those of shallow water may have resulted from the accumulation of decelerating turbulent suspensions of low density currents. Available detailed information from the evolution of the Neuquén Basin during the episodes without marine deposition is still scarce, particularly for the late Jurassic. This determines great limitations for reconstructing that evolution within a paleogeographic, magmatic and tectonic context. This study gives some clues for a better understanding of these aspects.

  15. Large Alluvial Fans on Mars

    NASA Technical Reports Server (NTRS)

    Moore, Jeffrey M.; Howard, Alan D.

    2004-01-01

    Several dozen distinct alluvial fans, 10 to greater than 40 km long downslope are observed exclusively in highlands craters. Within a search region between 0 deg. and 30 deg. S, alluvial fan-containing craters were only found between 18 and 29 S, and they all occur at around plus or minus 1 km of the MOLA-defined Martian datum. Within the study area they are not randomly distributed but instead form three distinct clusters. Fans typically descend greater than 1 km from where they disgorge from their alcoves. Longitudinal profiles show that their surfaces are very slightly concave with a mean slope of 2 degrees. Many fans exhibit very long, narrow low-relief ridges radially oriented down-slope, often branching at their distal ends, suggestive of distributaries. Morphometric data for 31 fans was derived from MOLA data and compared with terrestrial fans with high-relief source areas, terrestrial low gradient alluvial ramps in inactive tectonic settings, and older Martian alluvial ramps along crater floors. The Martian alluvial fans generally fall on the same trends as the terrestrial alluvial fans, whereas the gentler Martian crater floor ramps are similar in gradient to the low relief terrestrial alluvial surfaces. For a given fan gradient, Martian alluvial fans generally have greater source basin relief than terrestrial fans in active tectonic settings. This suggests that the terrestrial source basins either yield coarser debris or have higher sediment concentrations than their Martian counterpoints. Martian fans and Basin and Range fans have steeper gradients than the older Martian alluvial ramps and terrestrial low relief alluvial surfaces, which is consistent with a supply of coarse sediment. Martian fans are relatively large and of low gradient, similar to terrestrial fluvial fans rather than debris flow fans. However, gravity scaling uncertainties make the flow regime forming Martian fans uncertain. Martian fans, at least those in Holden crater, apparently formed around the time of the Noachian-Hesperian boundary. We infer that these fans formed during an episode of enhanced precipitation (probably snow) and runoff, which exhibited both sudden onset and termination.

  16. Modeling flash flood events in an ungaged semi-arid basin using a real-time distributed model: Fish Creek near Anza Borrego, California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fast responding headwater basins and canyons pose a significant threat to life and property throughout the semi-arid western United States. This paper presents the results from the application of the real-time distributed model KINematic runoff and EROsin model (KINEROS2) to the complex terrain of t...

  17. Responses of shelterbelt stand transpiration to drought and groundwater variations in an arid inland river basin of Northwest China

    NASA Astrophysics Data System (ADS)

    Shen, Qin; Gao, Guangyao; Fu, Bojie; Lü, Yihe

    2015-12-01

    Plant water use characteristics and transpiration responses under dry conditions are considered essential for effective and sustainable ecosystem management in arid areas. This study was conducted to evaluate the response of shelterbelt stand transpiration to precipitation, soil drought and groundwater variations in an oasis-desert ecotone in the middle of the Heihe River Basin, China. Sap flow was measured in eight Gansu Poplar trees (Populus Gansuensis) with different diameter at breast height over three consecutive growing seasons (2012-2014). The groundwater evapotranspiration via plant use was estimated by the White method with diurnal water table fluctuations. The results showed that precipitation increased the stand transpiration but not statistically significant (paired t-test, p > 0.05). The recharge of soil water by irrigation caused stand transpiration acceleration significantly (t-test, p < 0.05). Stand transpiration and canopy conductance increased by 27% and 31%, respectively, when soil water conditions changed from dry to wet. Canopy conductance decreased logarithmically with vapor pressure deficit, while there was no apparent relationship between canopy conductance and solar radiation. The sensitivity of canopy conductance to vapor pressure deficit decreased under dry soil conditions. Groundwater evapotranspiration (0.6-7.1 mm day-1) was linearly correlated with stand transpiration (1.1-6.5 mm day-1) (R2 = 0.71), and these two variables had similar variability. During the drought period, approximately 80% of total stand transpiration came from groundwater evapotranspiration. This study highlighted the critical role of irrigation and groundwater for shelterbelt, and might provide the basis for the development of water requirement schemes for shelterbelt growth in arid inland river basins.

  18. Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production

    NASA Astrophysics Data System (ADS)

    Lockhart, K. M.; King, A. M.; Harter, T.

    2013-08-01

    Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. The San Joaquin Valley, California, is an example of an agricultural landscape with a large diversity of field, vegetable, tree, nut, and citrus crops, but also confined animal feeding operations (CAFOs, here mostly dairies) that generate, store, and land apply large amounts of liquid manure. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (≤ 150 m deep), of which many have been affected by nitrate. Variability in crops, soil type, and depth to groundwater contribute to large variability in nitrate occurrence across the underlying aquifer system. The role of these factors in controlling groundwater nitrate contamination levels is examined. Two hundred domestic wells were sampled in two sub-regions of the San Joaquin Valley, Stanislaus and Merced (Stan/Mer) and Tulare and Kings (Tul/Kings) Counties. Forty six percent of well water samples in Tul/Kings and 42% of well water samples in Stan/Mer exceeded the MCL for nitrate (10 mg/L NO3-N). For statistical analysis of nitrate contamination, 78 crop and landuse types were considered by grouping them into ten categories (CAFO, citrus, deciduous fruits and nuts, field crops, forage, native, pasture, truck crops, urban, and vineyards). Vadose zone thickness, soil type, well construction information, well proximity to dairies, and dominant landuse near the well were considered. In the Stan/Mer area, elevated nitrate levels in domestic wells most strongly correlate with the combination of very shallow (≤ 21 m) water table and the presence of either CAFO derived animal waste applications or deciduous fruit and nut crops (synthetic fertilizer applications). In Tulare County, statistical data indicate that elevated nitrate levels in domestic well water are most strongly associated with citrus orchards when located in areas with a very shallow (≤ 21 m) water table. Kings County had relatively few nitrate MCL exceedances in domestic wells, probably due to the deeper water table in Kings County.

  19. Simulated ground-water flow in the Hueco Bolson, an alluvial-basin aquifer system near El Paso, Texas

    USGS Publications Warehouse

    Heywood, Charles E.; Yager, Richard M.

    2003-01-01

    The neighboring cities of El Paso, Texas, and Ciudad Juarez, Chihuahua, Mexico, have historically relied on ground-water withdrawals from the Hueco Bolson, an alluvial-aquifer system, to supply water to their growing populations. By 1996, ground-water drawdown exceeded 60 meters in some areas under Ciudad Juarez and El Paso. A simulation of steady-state and transient ground-water flow in the Hueco Bolson in westernmost Texas, south-central New Mexico, and northern Chihuahua, Mexico, was developed using MODFLOW-96. The model is needed by El Paso Water Utilities to evaluate strategies for obtaining the most beneficial use of the Hueco Bolson aquifer system. The transient simulation represents a period of 100 years beginning in 1903 and ending in 2002. The period 1903 through 1968 was represented with 66 annual stress periods, and the period 1969 through 2002 was represented with 408 monthly stress periods. The ground-water flow model was calibrated using MODFLOWP and UCODE. Parameter values representing aquifer properties and boundary conditions were adjusted through nonlinear regression in a transient-state simulation with 96 annual time steps to produce a model that approximated (1) 4,352 water levels measured in 292 wells from 1912 to 1995, (2) three seepage-loss rates from a reach of the Rio Grande during periods from 1979 to 1981, (3) three seepage-loss rates from a reach of the Franklin Canal during periods from 1990 to 1992, and (4) 24 seepage rates into irrigation drains from 1961 to 1983. Once a calibrated model was obtained with MODFLOWP and UCODE, the optimal parameter set was used to create an equivalent MODFLOW-96 simulation with monthly temporal discretization to improve computations of seepage from the Rio Grande and to define the flow field for a chloride-transport simulation. Model boundary conditions were modified at appropriate times during the simulation to represent changes in well pumpage, drainage of agricultural fields, and channel modifications of the Rio Grande. The model input was generated from geographic information system databases, which facilitated rapid model construction and enabled testing of several conceptualizations of hydrogeologic facies boundaries. Specific yield of unconfined layers and hydraulic conductance of Quaternary faults in the fluvial facies were the most sensitive model parameters, suggesting that ground-water flow is impeded across the fault planes.

  20. Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production.

    PubMed

    Lockhart, K M; King, A M; Harter, T

    2013-08-01

    Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. The San Joaquin Valley, California, is an example of an agricultural landscape with a large diversity of field, vegetable, tree, nut, and citrus crops, but also confined animal feeding operations (CAFOs, here mostly dairies) that generate, store, and land apply large amounts of liquid manure. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (?150 m deep), of which many have been affected by nitrate. Variability in crops, soil type, and depth to groundwater contribute to large variability in nitrate occurrence across the underlying aquifer system. The role of these factors in controlling groundwater nitrate contamination levels is examined. Two hundred domestic wells were sampled in two sub-regions of the San Joaquin Valley, Stanislaus and Merced (Stan/Mer) and Tulare and Kings (Tul/Kings) Counties. Forty six percent of well water samples in Tul/Kings and 42% of well water samples in Stan/Mer exceeded the MCL for nitrate (10mg/L NO3-N). For statistical analysis of nitrate contamination, 78 crop and landuse types were considered by grouping them into ten categories (CAFO, citrus, deciduous fruits and nuts, field crops, forage, native, pasture, truck crops, urban, and vineyards). Vadose zone thickness, soil type, well construction information, well proximity to dairies, and dominant landuse near the well were considered. In the Stan/Mer area, elevated nitrate levels in domestic wells most strongly correlate with the combination of very shallow (?21 m) water table and the presence of either CAFO derived animal waste applications or deciduous fruit and nut crops (synthetic fertilizer applications). In Tulare County, statistical data indicate that elevated nitrate levels in domestic well water are most strongly associated with citrus orchards when located in areas with a very shallow (?21 m) water table. Kings County had relatively few nitrate MCL exceedances in domestic wells, probably due to the deeper water table in Kings County. PMID:23800783

  1. Why conceptual groundwater flow models matter: a trans-boundary example from the arid Great Basin, western USA

    NASA Astrophysics Data System (ADS)

    Gillespie, J.; Nelson, S. T.; Mayo, A. L.; Tingey, D. G.

    2012-09-01

    Spring and Snake valleys, western USA, are scheduled for development and groundwater export to Las Vegas, Nevada (USA). New work, compared to published studies, illustrates the critical role of conceptual models to underpin water withdrawals in arid regions. Interbasin flow studies suggest that 30-55 % of recharge to Snake Valley arrives from adjacent Spring Valley. This study, however, suggest little or no interbasin flow; rather, Spring and Snake valleys comprise separate systems. Contrary to expectation, ?D and ?18O contours are perpendicular to proposed interbasin flow paths. 14C age gradients up to 10 ka along interbasin flow paths indicate that old waters are not displaced by such fluxes. 14C and 3H patterns indicate local recharge occurs in adjacent mountain ranges and is transferred to basin-fill by losing streams, mountain front recharge, and upward leakage from carbonate bedrock beneath basins. The choice of conceptual models is critical for groundwater development. Simple analyses of water withdrawals indicate that monitoring discharges at desert springs is an inadequate protective measure. Once flows decline, recovery is lengthy even if pumping is stopped. The conceptual framework behind quantitative evaluations of sustainable yield is critical to determine the ability of a groundwater system to deliver sustained withdrawals.

  2. ERODIBILITY OF URBAN BEDROCK AND ALLUVIAL CHANNELS, NORTH TEXAS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Major erosion of urban stream channels is found in smaller basins in the North Texas study area with contributing drainage areas of less than ten square miles. Within these basins, four basic channel types are identified based on bed and bank lithologies: alluvial banks and bottoms, alluvial banks ...

  3. Northwest Arid Lands : an introduction to the Columbia Basin shrub-steppe

    SciTech Connect

    O'Connor, Georganne P. ); Wieda, Karen J. )

    2001-04-15

    This book explores the rich variety of life in shrub-steppe lands of the Columbia River Basin. It describes, for a non-technical audience, the flora, fauna, and geology of the lower Columbia Basin in and around the Tri-Cities, Washington. Features include color photos and maps of shrub-steppe plants and animals; lists and illustration of common plants, mammals, reptiles, amphibians, birds, fish, and species of conservation concern; tips on places to see wildflowers and wildlife; geological travel logs from the Tri-Cities to Seattle and Spokane; and a comprehensive bibliography and definition of ecological terms.

  4. Hydrogeochemical zonation and its implication for arsenic mobilization in deep groundwaters near alluvial fans in the Hetao Basin, Inner Mongolia

    NASA Astrophysics Data System (ADS)

    Jia, Yongfeng; Guo, Huaming; Jiang, Yuxiao; Wu, Yang; Zhou, Yinzhu

    2014-10-01

    High As groundwater has been found in shallow aquifers of the flat plain of the Hetao basin, but little is known about As concentration in deep groundwaters around piedmont areas, which are the major drinking water resources. One hundred and three groundwater samples from wells with depths >50 m and seven samples from one multi-level monitoring well (89 m in depth) were analyzed for chemical compositions and 18O and D isotopes to examine the geochemical processes controlling As mobilization. According to hydrogeological setting, chemical and isotopic characteristics of deep groundwater, three distinguished hydrogeochemical zones are delineated, including Recharge-Oxic Zone (Zone I), Groundwater Flow-Moderate Reducing Zone (Zone II), and Groundwater Flow-Reducing Zone (Zone III). Zone I is located in proximal fans in the recharge area with oxic conditions, where low As groundwater generally occurs. In Zone II, located in the intermediate between the fans and the flat plain with Fe-reduction predominated, groundwater As is moderate. Zone III lies in the flat plain with the occurrence of SO42- reduction, where high As groundwater is mostly found. This indicates that release of As to groundwater is primarily determined by reduction sequences. Arsenic is immobilized in O2 /NO3- reduction stage in Zone I and released in Fe-reducing conditions of Zone II, and displays a significant elevated concentration in SO4-reducing stage in Zone III. Dissolution of carbonate minerals occurs in Zone I, while Ca2+ and Mg2+ are expected to precipitate in Zone II and Zone III. In the multi-level monitoring well, both chemical and isotopic compositions are dependent of sampling depths, with the similar trend to the hydrogeochemical zonation along the flow path. The apparent increases in δD and δ18O values in Zone III reveal the possibility of high As shallow groundwater recharge to deep groundwater. It indicates that deep groundwaters in proximal fans have low As concentrations and are considered as safe drinking water resources in the Hetao basin. However, high As concentration is frequently observed in deep groundwater in the flat plain, which should be routinely monitored in order to avoid chronic As poisoning.

  5. Paired Catchment Modeling Study for a Monsoon Flood Event in Neighboring Semi-Arid Basins, New Mexico

    NASA Astrophysics Data System (ADS)

    Wyckoff, R. L.; Vivoni, E. R.

    2005-12-01

    Flooding in ephemeral stream networks can significantly impact channel geomorphology, sediment transport, biogeochemical cycles, and water availability for consumptive and recreational use. In order to better understand the spatial patterns of flooding, distributed models may provide an opportunity for further investigation of rainfall-runoff dynamics in headwater semi-arid catchments including flood generation in ungauged portions of a watershed. For example, the Rio Puerco in west-central New Mexico is an ephemeral tributary of the Rio Grande spanning approximately 18,896 km2 with mountainous forests to the north and semi-arid desert to the south. In mid-September 2003, a series of late monsoonal storms traversed the northern extent of watershed resulting in a flood pulse which propagated through the main reach of the catchment and into the Rio Grande thereby substantially influencing streamflow as far south as Elephant Butte Reservoir (289 km). Radar data suggests flooding most likely emanated from two neighboring sub-catchments within the upper reaches of the watershed. In order to better understand the source of significant hydrologic events within the catchment, we utilize a fully distributed model to simulate the flood within the gauged Upper Rio Puerco Watershed (1119 km2) as well as the immediately adjacent but ungauged Torreon Wash (1344 km2). The TIN-Based Real-time Integrated Basin Simulator (tRIBS) prioritizes interactions between the vadose and saturated zone through the simulation of downward moving infiltration fronts and a variable groundwater surface. Topography is captured through a multiple resolution triangular irregular network (TIN) which accurately represents changes in elevation and simultaneously diminishes the model's computational demands. In addition to faithfully modeling topographic features, tRIBS requires accurate representation and calibration of soil, land use features, and geomorphic data. Calibration is performed through a manual procedure in which parameter values are adjusted in an effort to match an observed stream hydrograph with the model output for a series of storm and inter-storm periods. Following model calibration, we transfer the parameter set to the neighboring Torreon Wash. Model results for the paired catchment study demonstrate the appropriateness of parameter transfer between two neighboring semi-arid catchments.

  6. Geomorphology of the Alluvial Sediments and Bedrock in an Intermontane Basin: Application of Variogram Modeling to Electrical Resistivity Soundings

    NASA Astrophysics Data System (ADS)

    Khan, Adnan Ahmad; Farid, Asam; Akhter, Gulraiz; Munir, Khyzer; Small, James; Ahmad, Zulfiqar

    2016-02-01

    The study describes a methodology used to integrate legacy resistivity data with limited geological data in order to build three-dimensional models of the near subsurface. Variogram analysis and inversion techniques more typically found in the petroleum industry are applied to a set of 1D resistivity data taken from electrical surveys conducted in the 1980s. Through careful integration with limited geological data collected from boreholes and outcrops, the resultant model can be visualized in three dimensions to depict alluvium layers as lithological and structural units within the bedrock. By tuning the variogram parameters to account for directionality, it is possible to visualize the individual lithofacies and geomorphological features in the subsurface. In this study, an electrical resistivity data set collected as part of a groundwater study in an area of the Peshawar basin in Pakistan has been re-examined. Additional lithological logs from boreholes throughout the area have been combined with local outcrop information to calibrate the data. Tectonic activity during the Himalayan orogeny has caused uplift in the area and generated significant faulting in the bedrock resulting in the formation of depressions which are identified by low resistivity values representing clays. Paleo-streams have reworked these clays which have been eroded and replaced by gravel-sand facies along paleo-channels. It is concluded that the sediments have been deposited as prograding fan-shaped bodies and lacustrine deposits with interlayered gravel-sand and clay-silt facies. The Naranji area aquifer system has thus been formed as a result of local tectonic activity with fluvial erosion and deposition and is characterized by coarse sediments with high electrical resistivities.

  7. Late Miocene episodic lakes in the arid Tarim Basin, western China

    PubMed Central

    Liu, Weiguo; Liu, Zhonghui; An, Zhisheng; Sun, Jimin; Chang, Hong; Wang, Ning; Dong, Jibao; Wang, Huanye

    2014-01-01

    The Tibetan Plateau uplift and Cenozoic global cooling are thought to induce enhanced aridification in the Asian interior. Although the onset of Asian desertification is proposed to have started in the earliest Miocene, prevailing desert environment in the Tarim Basin, currently providing much of the Asian eolian dust sources, is only a geologically recent phenomenon. Here we report episodic occurrences of lacustrine environments during the Late Miocene and investigate how the episodic lakes vanished in the basin. Our oxygen isotopic (δ18O) record demonstrates that before the prevailing desert environment, episodic changes frequently alternating between lacustrine and fluvial-eolian environments can be linked to orbital variations. Wetter lacustrine phases generally corresponded to periods of high eccentricity and possibly high obliquity, and vice versa, suggesting a temperature control on the regional moisture level on orbital timescales. Boron isotopic (δ11B) and δ18O records, together with other geochemical indicators, consistently show that the episodic lakes finally dried up at ∼4.9 million years ago (Ma), permanently and irreversibly. Although the episodic occurrences of lakes appear to be linked to orbitally induced global climatic changes, the plateau (Tibetan, Pamir, and Tianshan) uplift was primarily responsible for the final vanishing of the episodic lakes in the Tarim Basin, occurring at a relatively warm, stable climate period. PMID:25368156

  8. Late Miocene episodic lakes in the arid Tarim Basin, western China.

    PubMed

    Liu, Weiguo; Liu, Zhonghui; An, Zhisheng; Sun, Jimin; Chang, Hong; Wang, Ning; Dong, Jibao; Wang, Huanye

    2014-11-18

    The Tibetan Plateau uplift and Cenozoic global cooling are thought to induce enhanced aridification in the Asian interior. Although the onset of Asian desertification is proposed to have started in the earliest Miocene, prevailing desert environment in the Tarim Basin, currently providing much of the Asian eolian dust sources, is only a geologically recent phenomenon. Here we report episodic occurrences of lacustrine environments during the Late Miocene and investigate how the episodic lakes vanished in the basin. Our oxygen isotopic (δ(18)O) record demonstrates that before the prevailing desert environment, episodic changes frequently alternating between lacustrine and fluvial-eolian environments can be linked to orbital variations. Wetter lacustrine phases generally corresponded to periods of high eccentricity and possibly high obliquity, and vice versa, suggesting a temperature control on the regional moisture level on orbital timescales. Boron isotopic (δ(11)B) and δ(18)O records, together with other geochemical indicators, consistently show that the episodic lakes finally dried up at ∼4.9 million years ago (Ma), permanently and irreversibly. Although the episodic occurrences of lakes appear to be linked to orbitally induced global climatic changes, the plateau (Tibetan, Pamir, and Tianshan) uplift was primarily responsible for the final vanishing of the episodic lakes in the Tarim Basin, occurring at a relatively warm, stable climate period. PMID:25368156

  9. Geomorphic controls on hydrology and vegetation in an arid basin: Turkana district, northern Kenya

    SciTech Connect

    Coppinger, K.D.; Doehring, D.O.; Schimel, D.S.

    1985-01-01

    As part of a broad ecological study of Kenyan pastoralist adaptation to periodic drought, a study was done to determine how arid region geomorphology affects hydrology and subsequently vegetative patterns. In this study area, 100 kilometers south of Lake Turkana, it appears that irregular precipitation is stored in bajada sediments and is available to deeply rooted vegetation over long periods of time. This vegetation provides a relatively constant food source for people's herds of browsers, the camels and goats, whereas cattle, which graze mainly on grasses, are significant producers only during wet seasons. Field observations suggest that the mountain and abutting pediment soils are too shallow to store appreciable water. However, greater quantities of water are stored in the deeper bajada sediments adjacent to the pediment where pastoralists dig temporary wells in ephemeral channels during wet seasons. Density of tree growth is greater along channels, and highest canopy cover values are found about the pediment-bajada interface. Geohydrologic processes in this area provide the basis for continuous occupation by the desert people, in contrast to recurring famines in adjacent areas, by enhancing the growth of woody vegetation.

  10. Changes in Remotely Sensed Vegetation Growth Trend in the Heihe Basin of Arid Northwestern China.

    PubMed

    Sun, Wenchao; Song, Hao; Yao, Xiaolei; Ishidaira, Hiroshi; Xu, Zongxue

    2015-01-01

    The Heihe River Basin (HRB) is the second largest inland river basin in China, characterized by high diversity in geomorphology and irrigated agriculture in middle reaches. To improve the knowledge about the relationship between biotic and hydrological processes, this study used Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (NDVI) data (1982-2006) to analyze spatiotemporal variations in vegetation growth by using the Mann-Kendall test together with Sen's slope estimator. The results indicate that 10.1% and 1.6% of basin area exhibit statistically significant (p < 0.05) upward and downward trends, and maximum magnitude is 0.066/10a and 0.026/10a, respectively. More specifically, an increasing trend was observed in the Qilian Mountains and Hexi Corridor and a decreasing trend detected in the transitional region between them. Increases in precipitation and temperature may be one possible reason for the changes of vegetation growth in the Qilian Mountains. And decreasing trend in transitional region may be driven by the changes in precipitation. Increases of irrigation contribute to the upward trend of NDVI for cropland in the Hexi Corridor, reflecting that agricultural development becomes more intensive. Our study demonstrates the complexity of the response of vegetation growth in the HRB to climate change and anthropogenic activities and correspondingly adopting mechanistic ecological models capable of describing both factors is favorable for reasonable predictions of future vegetation growth. It is also indicated that improving irrigation water use efficiency is one practical strategy to balance water demand between human and natural ecosystems in the HRB. PMID:26284656

  11. Changes in Remotely Sensed Vegetation Growth Trend in the Heihe Basin of Arid Northwestern China

    PubMed Central

    Yao, Xiaolei; Ishidaira, Hiroshi; Xu, Zongxue

    2015-01-01

    The Heihe River Basin (HRB) is the second largest inland river basin in China, characterized by high diversity in geomorphology and irrigated agriculture in middle reaches. To improve the knowledge about the relationship between biotic and hydrological processes, this study used Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (NDVI) data (1982–2006) to analyze spatiotemporal variations in vegetation growth by using the Mann—Kendall test together with Sen’s slope estimator. The results indicate that 10.1% and 1.6% of basin area exhibit statistically significant (p < 0.05) upward and downward trends, and maximum magnitude is 0.066/10a and 0.026/10a, respectively. More specifically, an increasing trend was observed in the Qilian Mountains and Hexi Corridor and a decreasing trend detected in the transitional region between them. Increases in precipitation and temperature may be one possible reason for the changes of vegetation growth in the Qilian Mountains. And decreasing trend in transitional region may be driven by the changes in precipitation. Increases of irrigation contribute to the upward trend of NDVI for cropland in the Hexi Corridor, reflecting that agricultural development becomes more intensive. Our study demonstrates the complexity of the response of vegetation growth in the HRB to climate change and anthropogenic activities and correspondingly adopting mechanistic ecological models capable of describing both factors is favorable for reasonable predictions of future vegetation growth. It is also indicated that improving irrigation water use efficiency is one practical strategy to balance water demand between human and natural ecosystems in the HRB. PMID:26284656

  12. Hydrogeology of an ancient arid closed basin: Implications for tabular sandstone-hosted uranium deposits

    SciTech Connect

    Sanford, R.F. )

    1990-11-01

    Hydrogeologic modeling shows that tabular-type uranium deposits in the grants uranium region of the San Juan basin, New Mexico, formed in zones of ascending and discharging regional ground-water flow. The association of either lacustrine mudstone or actively subsiding structures and uranium deposits can best be explained by the occurrence of lakes at topographic depressions where ground water having different sources and compositions is likely to converge, mix, and discharge. Ascending and discharging flow also explains the association of uranium deposits with underlying evaporites and suggests a brine interface. The simulations contradict previous suggestions that ground water moved downward in the mudflat.

  13. Intensified pluvial conditions during the twentieth century in the inland Heihe River Basin in arid northwestern China over the past millennium

    NASA Astrophysics Data System (ADS)

    Qin, Chun; Yang, Bao; Burchardt, Iris; Hu, Xiaoli; Kang, Xingcheng

    2010-06-01

    Past streamflow variability is of special significance in the inland river basin, i.e., the Heihe River Basin in arid northwestern China, where water shortage is a serious environmental and social problem. However, the current knowledge of issues related to regional water resources management and long-term planning and management is limited by the lack of long-term hydro-meteorological records. Here we present a 1009-year annual streamflow (August-July) reconstruction for the upstream of the Heihe River in the arid northwestern China based on a well-replicated Qilian juniper ( Sabina przewalskii Kom.) ring-width chronology. This reconstruction accounts for 46.9% of the observed instrumental streamflow variance during the period 1958-2006. Considerable multidecadal to centennial flow variations below and above the long-term average are displayed in the millennium streamflow reconstruction. These periods 1012-1053, 1104-1212, 1259-1352, 1442-1499, 1593-1739 and 1789-1884 are noteworthy for the persistence of low-level river flow, and for the fact that these low streamflow events are not found in the observed instrumental hydrological record during the recent 50 years. The 20th century witnessed intensified pluvial conditions in the upstream of the Heihe River in the arid northwestern China in the context of the last millennium. Comparison with other long-term hydrological reconstructions indicates that the intensification of the hydrological cycle in the twentieth century from different regions could be attributable to regional to large-scale temperature increase during this time. Furthermore, from a practical perspective, the streamflow reconstruction can serve as a robust database for the government to work out more scientific and more reasonable water allocation alternatives for the Heihe River Basin in arid northwestern China.

  14. Observed changes of drought/wetness episodes in the Pearl River basin, China, using the standardized precipitation index and aridity index

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Xu, Chong-Yu; Zhang, Zengxin

    2009-09-01

    Monthly precipitation data of 42 rain stations over the Pearl River basin for 1960-2005 were analyzed to classify anomalously wet and dry conditions by using the standardized precipitation index (SPI) and aridity index ( I) for the rainy season (April-September) and winter (December-February). Trends of the number of wet and dry months decided by SPI were detected with Mann-Kendall technique. Furthermore, we also investigated possible causes behind wet and dry variations by analyzing NCAR/NCEP reanalysis dataset. The results indicate that: (1) the Pearl River basin tends to be dryer in the rainy season and comes to be wetter in winter. However, different wetting and drying properties can be identified across the basin: west parts of the basin tend to be dryer; and southeast parts tend to be wetter; (2) the Pearl River basin is dominated by dry tendency in the rainy season and is further substantiated by aridity index ( I) variations; and (3) water vapor flux, moisture content changes in the rainy season and winter indicate different influences of moisture changes on wet and dry conditions across the Pearl River basin. Increasing moisture content gives rise to an increasing number of wet months in winter. However, no fixed relationships can be observed between moisture content changes and number of wet months in the rainy season, indicating that more than one factor can influence the dry or wet conditions of the study region. The results of this paper will be helpful for basin-scale water resource management under the changing climate.

  15. Modeling Spatial Recharge in the Arid Southern Okanagan Basin and Impacts of Future Predicted Climate Change

    NASA Astrophysics Data System (ADS)

    Allen, D. M.; Toews, M. W.

    2007-12-01

    Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of evapotranspiration rates on temperature, and potential shifts in the precipitation amounts and timing. In this study, future predicted climate change from three GCMs (CGCM1 GHG+A, CGCM3.1 A2, and HadCM3 A2) are used to evaluate the sensitivity of recharge in the Oliver region of the Okanagan Valley, south- central British Columbia, where annual precipitation is approximately 300~mm. Temperature data were downscaled using Statistical Downscaling Model (SDSM), while precipitation and solar radiation changes were estimated directly from the GCM data. Results for the region suggest that temperature will increase up to 4°C by the end of the century. Precipitation is expected to decrease in the spring, and increase in the fall. Solar radiation may decrease in the late summer. Shifts in climate, from present to future-predicted, were applied to the LARS-WG stochastic weather generator to generate daily stochastic weather series. Recharge was modeled spatially using output from the HELP hydrologic model applied to one-dimensional soil columns. An extensive valley-bottom soil database was used to determine both the spatial variation and vertical assemblage of soil horizons in the Oliver region. Soil hydraulic parameters were estimated from soil descriptions using pedotransfer functions through the ROSETTA program. Leaf area index (LAI) was estimated from ground-truthed Landsat 5 TM imagery, and surface slope was estimated from a digital elevation model. Irrigation application rates were modified for each climate scenario based on estimates of seasonal crop water demand. Daily irrigation was added to precipitation in irrigation districts using proportions of crop types along with daily climate and evapotranspiration data from LARS-WG. The two dominant crop classes are orchard (including peaches, cherries and apples) and vineyards (grapes). Recharge in irrigated areas is significantly higher, with irrigation return flow between 25--58%. Recharge results show a general increase of annual recharge, with the peak recharge shifting from March to February. Lower recharge rates and higher potential evapotranspiration rates are expected in the summer. The minor increase of annual recharge in future predicted climate states is due the shift of peak recharge from increased temperature. Growing season lengths, as determined from growing degree day accumulation, are expected to lengthen by 3--4 weeks by the 2080s.

  16. Groundwater quality and management in arid and semi-arid regions: Case study, Central Eastern Desert of Egypt

    NASA Astrophysics Data System (ADS)

    Amer, Reda; Ripperdan, Robert; Wang, Tao; Encarnación, John

    2012-07-01

    This study presents a model budget for groundwater in the Central Eastern Desert of Egypt. The stable isotopic composition and hydrochemistry of groundwater samples collected from different aquifers were determined to identify recharge sources and water quality. Stable isotopic values suggest that shallow alluvial and fracture zone aquifers are recharged from seasonal precipitation, while groundwater in deeper sedimentary sub-basins is paleowater that was recharged during periods of less arid regional climate. Hydrochemical analysis indicates elevated salinity in each aquifer type, which is attributed to leaching and dissolution of terrestrial salts and to mixing with marine water. Groundwater from sedimentary sub-basin aquifers can be treated and used for drinking and domestic purposes. Groundwater from shallow alluvial and fracture zone wells is suitable for animal husbandry and mineral ore dressing. A model water budget shows that approximately 4.8 × 109 m3 of recoverable groundwater is stored in sedimentary sub-basin aquifers, or approximately 550 years of water at present utilization rates.

  17. Atmospheric-Ecosystem CO2 Exchange in Sparse Arid Shrublands Across the Great Basin USA Over Multiple Years: Identifying Patterns and Mechanisms

    NASA Astrophysics Data System (ADS)

    Arnone, J. A.; Jasoni, R. L.; Larsen, J. D.; Fenstermaker, L. F.; Wohlfahrt, G.

    2008-12-01

    Up to recently, desert ecosystems have essentially been ignored with respect to their influence on global carbon cycling and their potential role in modulating atmospheric CO2 levels. Because deserts, defined here as ecosystems receiving <280 mm of precipitation annually, cover 35% of Earth's surface, even small positive or negative net ecosystem CO2 exchange (NEE=fluxes) can have globally meaningful effects on atmospheric CO2. Since 2003 we have been measuring NEE and annual NEP at 10 arid shrubland sites around the Great Basin in Nevada, USA using eddy covariance and large static chamber "domes" with the objectives of quantifying seasonal, annual and interannual fluxes and the environmental and ecological factors that may be modulating these fluxes. Surprisingly, annual NEP measured in Mojave Desert creosote bush (Larrea tridentata)-dominated ecosystems, high desert sagebrush steppe (Aremesia tridentata) ecosystems, and greasewood (Sarcobatus vermiculatus) ecosystems have been largely positive (net C uptake by ecosystems; range of zero to 90 g C m-2 yr-1) and often large (as high 100 to 180 g C m-2 yr-1). Thus, the data from these arid shrublands suggest a much larger arid land C sink than has been previously assumed and call for closer tracking of the CO2 fluxes in these ecosystems.

  18. [Influence of soil salinization on soil animal community in an arid oasis of middle Heihe River basin].

    PubMed

    Liu, Ji-Liang; Li, Feng-Rui; Niu, Rui-Xue; Liu, Chang-An; Liu, Qi-Jun

    2012-06-01

    An investigation was conducted on the status of soil salinization and the structure of soil animal community across six land use/cover types in an arid oasis of middle Heihe River basin, and the methods of redundancy analysis, regression analysis, and path analysis were adopted to analyze the responses of the soil animal community under different land use/cover types and different management modes to the various status of soil salinization. The six land use/cover types were 21-year old shrub land without irrigation and fertilization, 28-year old poplar and 33-year-old pine plantations with irrigation, 27- and 100-year-old farmlands with irrigation and fertilization, and natural grassland, from which all the other five land use/cover types were converted. The results demonstrated that land cover change in the absence of management practices did not lead to a significant change in the abundance and group richness of the soil animal community, while land cover change in the presence of management practices resulted in a significant change in the soil animal community. The evolvement of the soil animal community structure was co-affected by soil pH, soluble salt content, and Na+, Cl, HCO3-, and Mg2+ concentrations, among which, soil soluble salt and Na had the greatest contribution, being the key affecting factors. The abundance and group richness of the soil animal community had significant negative exponential correlations with soil soluble salt content and Na+ concentration, and significant quadratic correlations with soil Mg2+ and HCO3- concentrations. The calculated ecological threshold values of soil Mg2+ and HCO3- concentrations for the abundance and group richness of the soil animal community were 38.7-39.4 mg x kg(-1) and 324.9-335.3 mg x kg(-1), at which, the abundance and group richness reached their peaks 40-43 individuals x m(-2) and 13-14 families x m(-2), respectively. When the Mg2+ and HCO3- concentrations increased further, the abundance and group richness decreased. PMID:22937643

  19. Development of a 3D groundwater flow model with scarce data in semi-arid to arid region: the western drainage basin of the Dead Sea (Israel and West Bank)

    NASA Astrophysics Data System (ADS)

    Gräbe, A.; Rink, K.; Fischer, T.; Sun, F.; Rödiger, T.; Kolditz, O.

    2012-04-01

    Water is scarce in the semi-arid to arid region around the Dead Sea where water supply mostly relies on restricted groundwater resources. Because of population increase the regional groundwater body is exposed to additional stress, which also results in a continuous decrease of the Dead Sea level. As the interdependency between water demand from population increase and the decrease in groundwater availability will proceed over the next years, the stressed water supply situation appears to proceed also and possibly worsens unless sustainable changes are introduced. These changes however, can only be suggested if the hydrogeological situation in the tectonically complex region is fully understood. A number of simplified models of the Judea Group aquifer have been formulated and employed using a two-dimensional (one horizontal layered) numerical simulation of groundwater flow (Baida et al. 1978; Goldschtoff & Shachnai, 1980; Guttman, 2000; Laronne Ben-Itzhak & Gvirtzmann, 2005). However, all previous approaches focused only on a limited area of the Judea Group aquifer. We developed a high resolution regional groundwater flow model for the entire western basin of the Dead Sea. Whereas the structural model could be defined using a large geological dataset, the challenge was to generate the groundwater flow model with only limited well data. With the help of the scientific software OpenGeoSys (OGS) the challenge was reliably solved resulting in a simulation of the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system, which was calibrated using PEST.

  20. Understanding hydrologic budgets, dynamics in an arid basin and explore spatial scaling properties using Process-based Adaptive Watershed Simulator (PAWS)

    NASA Astrophysics Data System (ADS)

    Fang, K.; Shen, C.; Salve, R.

    2013-12-01

    The Southern California hot desert hosts a fragile ecosystem as well as a range of human economic activities, primarily mining, energy production and recreation. This inland arid landscape is characterized by occasional intensive precipitation events and year-round strong potential evapotranspiration. In this landscape, water and especially groundwater is vital for ecosystem functions and human use. However, the impact of recent development on the sustainability of groundwater resources in the area has not been thoroughly investigated. We apply an integrated, physically-based hydrologic-land surface model, the Process-based Adaptive Watershed Simulator + Community Land Model (PAWS+CLM) to evaluate the sustainability of the groundwater resources in the area. We elucidate the spatio-temporal patterns of hydrologic fluxes and budgets. The modeling results indicate that mountain front recharge is the essential recharging mechanism for the alluvial aquifer. Although pumping activities do not exceed annual-average recharge values, they are still expected to contribute significantly to groundwater drawdown in business-as-usual scenario. The impact of groundwater withdrawals is significant on the desert ecosystem. The relative importance of groundwater flow on NPP rises significantly as compared to other ecosystems. We further evaluate the fractal scaling properties of soil moisture in this very arid system and found the relationship to be much more static in time than that found in a humid continental climate system. The scaling exponents can be predicted using simple functions of the mean. Therefore, multi-scale model based on coarse-resolution surrogate model is expected to perform well in this system. The modeling result is also important for assessing the groundwater sustainability and impact of human activities in the desert environment.

  1. Alluvial Fans on Mars

    NASA Technical Reports Server (NTRS)

    Kraal, E. R.; Moore, J. M.; Howard, A. D.; Asphaug, E. A.

    2005-01-01

    Moore and Howard [1] reported the discovery of large alluvial fans in craters on Mars. Their initial survey from 0-30 S found that these fans clustered in three distinct regions and occurred at around the +1 km MOLA defined Mars datum. However, due to incomplete image coverage, Moore and Howard [1]could not conduct a comprehensive survey. They also recognized, though did not quantitatively address, gravity scaling issues. Here, we briefly discuss the identification of alluvial fans on Mars, then consider the general equations governing the deposition of alluvial fans and hypothesize a method for learning about grain size in alluvial fans on Mars.

  2. Using a physically-based model, tRIBS-Erosion, for investigating the effects of climate change in semi-arid headwater basins.

    NASA Astrophysics Data System (ADS)

    Francipane, Antonio; Fatichi, Simone; Ivanov, Valeriy Y.; Noto, Leonardo V.

    2013-04-01

    Soil erosion due to rainfall detachment and flow entrainment of soil particles is a physical process responsible for a continuous evolution of landscapes. The rate and spatial distribution of this phenomenon depend on several factors such as climate, hydrologic regime, geomorphic characteristics, and vegetation of a basin. Many studies have demonstrated that climate-erosion linkage in particular influences basin sediment yield and landscape morphology. Although soil erosion rates are expected to change in response to climate, these changes can be highly non-linear and thus require mechanistic understanding of underlying causes. In this study, an integrated geomorphic component of the physically-based, spatially distributed hydrological model, tRIBS, the TIN-based Real-time Integrated Basin Simulator, is used to analyze the sensitivity of semi-arid headwater basins to climate change. Downscaled outputs of global circulation models are used to inform a stochastic weather generator that produces an ensemble of climate scenarios for an area in the Southwest U.S. The ensemble is used as input to the integrated model that is applied to different headwater basins of the Walnut Gulch Experimental Watershed to understand basin response to climate change in terms of runoff and sediment yield. Through a model application to multiple catchments, a scaling relationship between specific sediment yield and drainage basin area is also addressed and probabilistic inferences on future changes in catchment runoff and yield are drawn. Geomorphological differences among catchments do not influence specific changes in runoff and sediment transport that are mostly determined by precipitation changes. Despite a large uncertainty dictated by climate change projections and stochastic variability, sediment transport is predicted to decrease despite a non-negligible possibility of larger runoff rates.

  3. Integrated Surface and Ground Water modeling of a tank cascaded sub basin using physically based model in a semi-arid region

    NASA Astrophysics Data System (ADS)

    Ilampooranan, I.; Muthiah, K.; Athikesavan, R.

    2013-05-01

    Hydrological Modeling of tank (small reservoirs) cascaded sub-basin of a semi-arid region is a complex process. Physically based approach can simulate the various processes in surface, unsaturated and saturated ground water zones of such sub basin in an integrated manner. The objectives of the study are (i) to characterize the study area to replicate the physical conditions of surface and saturated zones (ii) to carryout overland flow routing of a tank cascaded basin using physically based modular approach (iii) To simulate the ground water levels in the unconfined aquifer (iv) to study the surface and groundwater dynamics on incorporation of tank cascades in the integrated model. An integrated, physically based model MIKE 11 & MIKE SHE was applied to study the hydrological processes of a tank cascaded semi-arid basin in which flow through tanks were modeled using MIKE 11 and coupled with MIKE SHE in-order to best represent the surface water dynamics in a distributed manner. Sindapalli Uppodai sub-basin, Southern Tamilnadu, India is chosen as study area. There are 15 tanks connected in series forming a tank cascade. Other tanks and depressions in the sub basin are also considered for the study and their effectiveness were analysed. DEM was obtained from SRTM data. The maps such as drainage network, land use and soil are prepared. Soil sampling was carried out. The time series data of rainfall and climate parameters are given as input. The characterization of unconfined aquifer formation was done by Geo-Resistivity survey. 71 observation and pumping wells are monitored within and periphery of sub basin which are used for calibration of the model. The flow routing over the land is done by MIKE SHE's Overland Flow Module, using the diffusive wave approximation of the Saint Venant equation. The hydrograph of routed runoff from the tank cascaded catchment was obtained. The spatial and temporal variation of hydraulic head of the saturated ground water zone is simulated mathematically by three dimensional Darcy equation through ground water solver of MIKE SHE. Comprehensive budgeting of surface and ground water was made which will help the planners towards conserving and managing the scarce resources on a micro watershed level.

  4. Assessing the impacts of cooling methods of energy plants on groundwater resources in an arid basin and the delayed influence on the Colorado River leakance

    NASA Astrophysics Data System (ADS)

    Fang, K.; Shen, C.; Salve, R.

    2014-12-01

    Different cooling methods associated will utility-scale solar energy production utilize vastly different amounts of water. In a hyper-arid Southwestern US basin, where new energy projects are being developed, groundwater is the only available water for such cooling needs. The hydrologic impacts of groundwater withdrawal remain unclear, as recharge to the aquifer and exchange with the Colorado River are poorly quantified. The basin is also a data-scarce region, with few available groundwater parameter measurements for most of the basin. Characterized by a thick alluvium layer and deep aquifer, the basin also has a long response time to forcings. We employ both an integrated, physically-based surface-subsurface processes model (PAWS+CLM) and the MODFLOW+PEST package. The integrated model PAWS+CLM is used to estimate recharge while MODFLOW+PEST is used to estimate the groundwater conductivity fields. Calibration of the two models are iterated to obtain the best estimates of parameter values. We have identified the main area of recharge by forcing the model with both station-based measurements and NLDAS. The Colorado River is losing water in this reach. Using the combined, coupled model, we estimate the influence of cooling methods on the water table and its effect on the land-river exchange.

  5. Modeling the distributed effects of forest thinning on the long-term water balance and stream flow extremes for a semi-arid basin in the southwestern US

    NASA Astrophysics Data System (ADS)

    Moreno, H. A.; Gupta, H. V.; White, D. D.; Sampson, D. A.

    2015-10-01

    To achieve water resources sustainability in the water-limited Southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basin-wise stream flows. In Arizona, the Four Forest Restoration Initiative (4FRI) is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed tRIBS model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde-Tonto-Salt (VTS) system, which provides much of the water supply for the Phoenix Metropolitan Area. Long-term (20 year) simulations indicate that forest removal can trigger significant shifts in the spatio-temporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge, and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum stream flow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snow pack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  6. Comparison of multi-monthly rainfall-based drought severity indices, with application to semi-arid Konya closed basin, Turkey

    NASA Astrophysics Data System (ADS)

    Dogan, Selim; Berktay, Ali; Singh, Vijay P.

    2012-11-01

    SummaryMany drought indices (DIs) have been introduced to monitor drought conditions. This study compares Percent of Normal (PN), Rainfall Decile based Drought Index (RDDI), statistical Z-Score, China-Z Index (CZI), Standardized Precipitation Index (SPI), and Effective Drought Index (EDI) to identify droughts in a semi-arid closed basin (Konya), Turkey. Comparison studies of DIs under different climatic conditions is always interesting and may be insightful. Employing and comparing 18 different timesteps, the objective of comparison is twofold: (1) to determine the effect of timestep for choosing an appropriate value, and (2) to determine the sensitivity of DI to timestep and the choice of a DI. Monthly rainfall data obtained from twelve spatially distributed stations was used to compare DIs for timesteps ranging from 1 month to 48 months. These DIs were evaluated through correlations for various timesteps. Surprisingly, in many earlier studies, only 1-month time step has been used. Results showed that the employment of median timesteps was essential for future studies, since 1-month timestep DIs were found as irrelevant to those for other timesteps in arid/semi-arid regions because seasonal rainfall deficiencies are common there. Comparing time series of various DI values (numerical values of drought severity) instead of drought classes was advantageous for drought monitoring. EDI was found to be best correlated with other DIs when considering all timesteps. Therefore, drought classes discerned by DIs were compared with EDI. PN and RDDI provided different results than did others. PN detected a decrease in drought percentage for increasing timestep, while RDDI overestimated droughts for all timesteps. SPI and CZI were more consistent in detecting droughts for different timesteps. The response of DI and timestep combination to the change of monthly and multi-monthly rainfall for a qualitative comparison of severities (drought classes) was investigated. Analyzing the 1973-1974 dry spell at Beysehir station, EDI was found sensitive to monthly rainfall changes with respect to cumulative rainfall changes, especially more sensitive than other DIs for shorter timesteps. Overall, EDI was consistent with DIs for various timesteps and was preferable for monitoring long-term droughts in arid/semi-arid regions. The use of various DIs for timesteps of 6, 9, and 12 months is essential for long term drought studies. 1-month DIs should not be used solely in comparison studies to present a DI, unless there is a specific reason. This investigation showed that the use of an appropriate timestep is as important as the type of DI used to identify drought severities.

  7. Isotopic evidence for climatic influence on alluvial-fan development in Death Valley, California

    SciTech Connect

    Dorn, R.I.; DeNiro, M.J.; Ajie, H.O.

    1987-02-01

    At least three semiarid to arid cycles are recorded by ..delta../sup 13/C values of organic matter in layers of rock varnishes on surfaces of Hanaupah Canyon and Johnson Canyon alluvial fans, Death Valley, California. These isotopic paleoenvironmental signals are interpreted as indicating major periods of fan aggradation during relatively more humid periods and fan entrenchment during subsequent lengthy arid periods.

  8. End-Pleistocene to Holocene paleoenvironmental record from piston corer samples and the challenge of stratigraphic correlation of playa sediment data with a connected alluvial apron from Damghan Basin, Iran

    NASA Astrophysics Data System (ADS)

    Büdel, Christian; Hoelzmann, Philipp; Wennrich, Volker; Majid Padashi, Sajed; Baumhauer, Roland

    2015-04-01

    The study yields a first characterization and correlation of the end-Pleistocene to Holocene sediment archive of playa and playa lake deposits in the Damghan Basin, northern Iran. The Basin sediments are deposited since Mio- and Pliocene, which is valid for the connected alluvial fans, too. These are covering the area between the playa and mountains and while prograding from the mountain ranges they deliver gravels and fine-sediments to the basins sink. The processes on the studied alluvial apron are described and dated already and can be explained in seven morphodynamic phases, which are linked to a general lake level high-stand in north-east Iran at about 8000-9000 years ago. If and how these phases are passed on from the alluvial record down to the playa sediment record is aim of this study. Today the salt pans margins are highly affected by salt tectonic drifting and access was suboptimal. Only here drilling could be performed through about 280 centimeters of salt-crust unfrequently intercalated with loamy layers. For yielding undisturbed playa sediment records sampling was performed with inliner-tubes deployed in a piston corer (Kullenberg type). Thus at two different drilling sites in summation seven cores could be taken, down to a maximum depth of 129 cm and 1000 cm. Back in Germany the cores had been opened and initially described, photographed and optically scanned with a core logger. Regarding future studies, the aim was a best possible comprehensive documentation of the cores. Therefore basically grainsize measurements (laser diffraction), multi element analyses (XRF, ICP-OES, titrimetry) and mineralogical measurements (XRD) had been deployed on samples taken from every single previously identified layer. Continuous elemental data was secured by use of a XRF-scanning core logger. The sedimentological description together with laboratory element analyses shows saline conditions in the first three meters coincide with general coarser grain sizes. The next three meters are made up by homogenous partly laminated deposits, rich auf clay and silt and with a decreased content of sulphur and halite. Regular Peaks of sulfate and calcium within this unit presumably indicate post-sedimentary precipitation of gypsum. The homogenous sediment unit is followed by layers clearly set up in three major phases of up-fining sediments. Higher Al and Mg contents following this sedimentation phases suggest a considerable amount of syn-sedimentary clay mineral enrichment. The alignment of alluvial fan phases and phases recorded in the playa is challenging. As figured out before, the focused signals in the study are linked to non-local factors affecting supra-regional land surface alteration. But 0 to less than 1 % organic carbon contents decrease the chance of deriving a valid sediment dating and the possibility of chrono-stratigraphic correlation. Anyway, the clear transitional zone from halite dominated to more or less halite-free sediments can serve as a guideline to the development of further correlations.

  9. Rain Basin Design Implications for Soil Microbial Activity and N-mineralization in a Semi-arid Environment

    NASA Astrophysics Data System (ADS)

    Stern, C.; Pavao-Zuckerman, M.

    2014-12-01

    Rain basins have been an increasingly popular Green Infrastructure (GI) solution to the redistribution of water flow caused by urbanization. This study was conducted to examine how different approaches to basin design, specifically mulching (gravel vs. compost and gravel), influence the water availability of rain basins and the effects this has on the soil microbial activity of the basins. Soil microbes are a driving force of biogeochemical process and may impact the carbon and nitrogen dynamics of rain basin GI. In this study we sampled 12 different residential-scale rain basins, differing in design established at Biosphere 2, Arizona in 2013. Soil samples and measurements were collected before and after the onset of the monsoon season in 2014 to determine how the design of basins mediates the transition from dry to wet conditions. Soil abiotic factors were measured, such as moisture content, soil organic matter (SOM) content, texture and pH, and were related to the microbial biomass size within the basins. Field and lab potential N-mineralization and soil respiration were measured to determine how basin design influences microbial activity and N dynamics. We found that pre-monsoon basins with compost had higher moisture contents and that there was a positive correlation between the moisture content and the soil microbial biomass size of the basins. Pre-monsoon data also suggests that N-mineralization rates for basins with compost were higher than those with only gravel. These design influences on basin-scale biogeochemical dynamics and nitrogen retention may have important implications for urban biogeochemistry at neighborhood and watershed scales.

  10. The effect of vegetation and beaver dams on geomorphic recovery rates of incised streams in the semi-arid regions of the Columbia River basin, USA.

    NASA Astrophysics Data System (ADS)

    Pollock, M.; Beechie, T.; Jordan, C.

    2005-05-01

    Channel incision is a common occurrence in semi-arid regions of the Columbia River basin and throughout the world, where a fragile balance between climate, vegetation and geology makes channels susceptible to changes in hillslope erosion, stream discharge and sediment yield. Incision is defined as a rapid downcutting and lowering of the stream bed such that it reduces the frequency and duration of flooding onto the adjacent floodplain. We are studying the feasibility of restoring incised streams throughout the interior Columbia River basin. We hypothesize that under proper land use management, it is possible for them to aggrade such that they reconnect to their former floodplains within relatively short time frames. Theoretical and empirical evidence suggests that over decadal time scales, changes to land management that excludes grazing and allows riparian vegetation to become established can cause significant fill within the incised valleys. Preliminary modeling suggests that factors most affecting the length of time for an incised valley to completely aggrade and reconnect to its pre-incision floodplain are the depth of the incision, sediment production in the watershed, the amount and type of riparian vegetation, and the extent of beaver dam construction. While most natural resource and fisheries managers are aware of widespread incision throughout the Columbia River basin, the extent of incision within the range of the Pacific salmon is largely undocumented. However, we do know many incised streams that historically supported salmon no longer do so, and that habitat conditions are severely degraded in these incised streams. The historical record shows that numerous salmon-bearing streams in the semi-arid region of the interior Columbia River basin once contained narrow and deep, slowly meandering channels lined with cottonwoods, willows and/or sedges, contained numerous beaver dams, contained abundant and easily accessible off-channel habitat on the floodplain and had good flow and cool temperatures throughout most of the year. Today most of these streams are incised and contain little or no riparian vegetation or beaver dams. Stream temperatures are high and flow is ephemeral. Incision is thought to have lowered stream-adjacent water tables, causing both the loss of riparian vegetation and the increase in stream temperature. Many of these streams no longer support fish populations. We hypothesize that if incised streams were restored by creating conditions such that they could aggrade and reconnect to their former floodplains, that habitat conditions would be sufficient to again support salmon populations, and that this would greatly expand their range throughout much of the Columbia River basin.

  11. Enhanced sediment delivery in a changing climate in semi-arid mountain basins: Implications for water resource management and aquatic habitat in the northern Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Goode, Jaime R.; Luce, Charles H.; Buffington, John M.

    2012-02-01

    The delivery and transport of sediment through mountain rivers affects aquatic habitat and water resource infrastructure. While climate change is widely expected to produce significant changes in hydrology and stream temperature, the effects of climate change on sediment yield have received less attention. In the northern Rocky Mountains, we expect climate change to increase sediment yield primarily through changes in temperature and hydrology that promote vegetation disturbances (i.e., wildfire, insect/pathogen outbreak, drought-related die off). Here, we synthesize existing data from central Idaho to explore (1) how sediment yields are likely to respond to climate change in semi-arid basins influenced by wildfire, (2) the potential consequences for aquatic habitat and water resource infrastructure, and (3) prospects for mitigating sediment yields in forest basins. Recent climate-driven increases in the severity and extent of wildfire suggest that basin-scale sediment yields within the next few years to decades could be greater than the long-term average rate of 146 T km - 2 year - 1 observed for central Idaho. These elevated sediment yields will likely impact downstream reservoirs, which were designed under conditions of historically lower sediment yield. Episodic erosional events (massive debris flows) that dominate post-fire sediment yields are impractical to mitigate, leaving road restoration as the most viable management opportunity for offsetting climate-related increases in sediment yield. However, short-term sediment yields from experimental basins with roads are three orders of magnitude smaller than those from individual fire-related events (on the order of 10 1 T km - 2 year - 1 compared to 10 4 T km - 2 year - 1 , respectively, for similar contributing areas), suggesting that road restoration would provide a relatively minor reduction in sediment loads at the basin-scale. Nevertheless, the ecologically damaging effects of fine sediment (material < 6 mm) chronically produced from roads will require continued management efforts.

  12. The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

    NASA Astrophysics Data System (ADS)

    Han, WenXia; Yu, LuPeng; Lai, ZhongPing; Madsen, David; Yang, Shengli

    2014-07-01

    The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0-7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0-7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.

  13. Variations in fluvial deposition on an alluvial plain: an example from the Tongue River Member of the Fort Union Formation (Paleocene), southeastern Powder River Basin, Wyoming, U.S.A.

    USGS Publications Warehouse

    Johnson, E.A.; Pierce, F.W.

    1990-01-01

    The Tongue River Member of the Paleocene Fort Union Formation is an important coal-bearing sedimentary unit in the Powder River Basin of Wyoming and Montana. We studied the depositional environments of a portion of this member at three sites 20 km apart in the southeastern part of the basin. Six lithofacies are recognized that we assign to five depositional facies categorized as either channel or interchannel-wetlands environments. (1) Type A sandstone is cross stratified and occurs as lenticular bodies with concave-upward basal surfaces; these bodies are assigned to the channel facies interpreted to be the product of low-sinuosity streams. (2) Type B sandstone occurs in parallel-bedded units containing mudrock partings and fossil plant debris; these units constitute the levee facies. (3) Type C sandstone typically lacks internal structure and occurs as tabular bodies separating finer grained deposits; these bodies represent the crevasse-splay facies. (4) Gray mudrock is generally nonlaminated and contains ironstone concretions; these deposits constitute the floodplain facies. (5) Carbonaceous shale and coal are assigned to the swamp facies. We recognize two styles of stream deposition in our study area. Laterally continuous complexes of single and multistoried channel bodies occur at our middle study site and we interpret these to be the deposits of sandy braided stream systems. In the two adjacent study sites, single and multistoried channel bodies are isolated in a matrix of finer-grained interchannel sediment suggesting deposition by anastomosed streams. A depositional model for our study area contains northwest-trending braided stream systems. Avulsions of these systems created anastomosed streams that flowed into adjacent interchannel areas. We propose that during late Paleocene a broad alluvial plain existed on the southeastern flank of the Powder River Basin. The braided streams that crossed this surface were tributaries to a northward-flowing, basin-axis trunk stream that existed to the west. ?? 1990.

  14. Silicate weathering in the Ganges alluvial plain

    NASA Astrophysics Data System (ADS)

    Frings, Patrick J.; Clymans, Wim; Fontorbe, Guillaume; Gray, William; Chakrapani, Govind J.; Conley, Daniel J.; De La Rocha, Christina

    2015-10-01

    The Ganges is one of the world's largest rivers and lies at the heart of a body of literature that investigates the interaction between mountain orogeny, weathering and global climate change. Three regions can be recognised in the Ganges basin, with the Himalayan orogeny to the north and the plateaus of peninsular India to the south together delimiting the Ganges alluvial plain. Despite constituting approximately 80% of the basin, weathering processes in the peninsula and alluvial plain have received little attention. Here we present an analysis of 51 water samples along a transect of the alluvial plain, including all major tributaries. We focus on the geochemistry of silicon and its isotopes. Area normalised dissolved Si yields are approximately twice as high in rivers of Himalaya origin than the plain and peninsular tributaries (82, 51 and 32 kmol SiO2 km-2 yr-1, respectively). Such dissolved Si fluxes are not widely used as weathering rate indicators because a large but variable fraction of the DSi mobilised during the initial weathering process is retained in secondary clay minerals. However, the silicon isotopic composition of dissolved Si (expressed as δ30Si) varies from + 0.8 ‰ in the Ganges mainstem at the Himalaya front to + 3.0 ‰ in alluvial plain streams and appears to be controlled by weathering congruency, i.e. by the degree of incorporation of Si into secondary phases. The higher δ30Si values therefore reflect decreasing weathering congruency in the lowland river catchments. This is exploited to quantify the degree of removal using a Rayleigh isotope mass balance model, and consequently derive initial silica mobilisation rates of 200, 150 and 107 kmol SiO2 km-2 yr-1, for the Himalaya, peninsular India and the alluvial plain, respectively. Because the non-Himalayan regions dominate the catchment area, the majority of initial silica mobilisation from primary minerals occurs in the alluvial plain and peninsular catchment (41% and 34%, respectively).

  15. Particle Dynamics: Bedrock versus Alluvial River Segments

    NASA Astrophysics Data System (ADS)

    Wohl, E.

    2014-12-01

    Many channels alternate longitudinally between bedrock and alluvial substrate. These alternations occur over a range of spatial scales and associated temporal scales. Transient bedrock and alluvial patches alternate over downstream distances of a few meters to hundreds of meters, whereas persistent bedrock and alluvial reaches alternate downstream over distances of kilometers to hundreds of kilometers. These longitudinal alternations are significant because of the differences in process and form between bedrock and alluvial reaches. Bedrock reaches limit the response of the channel and the greater drainage basin to relative base level fall. Alluvial reaches limit the rate and distance of particle movement downstream, as well as limiting the habitat available for riverine organisms, biogeochemical reactions and nutrient storage, and water quality. In both types of substrate, particle movement is a limiting factor. (Here, particles include mineral sediment and particulate organic matter.) In bedrock channels, particle movement largely governs the rate and manner of erosion. In alluvial channels, particle movement governs channel form and the stability of habitat. Fundamental research questions for both channel types center on particle dynamics: How do interactions among bedrock substrate, sediment supply, sediment transport, and hydraulics influence rates of bedrock erosion? How do interactions among sediment supply, sediment transport, and biota influence particle transport and residence time? Although bedrock channel segments likely exert a more fundamental influence on river response to relative base level change and landscape evolution, alluvial channel segments likely exert a stronger limiting effect on downstream fluxes of water, solutes, and particles, as well as more critical influences on riverine habitat.

  16. Temporal correlation of fluvial and alluvial sequences in the Makran Range, SE-Iran

    NASA Astrophysics Data System (ADS)

    Kober, F.; Zeilinger, G.; Ivy-Ochs, S.; Dolati, A.; Smit, J.; Burg, J.-P.; Bahroudi, A.; Kubik, P. W.; Baur, H.; Wieler, R.; Haghipour, N.

    2009-04-01

    The Makran region of southeastern Iran is an active accretionary wedge with a partially subaerial component. New investigations have revealed a rather complex geodynamic evolution of the Makran active accretionary wedge that is not yet fully understood in its entity. Ongoing convergence between the Arabian and Eurasian plates and tectonic activity since the late Mesozoic has extended all trough the Quaternary. We focus here on fluvial and alluvial sequences in tectonically separated basins that have been deposited probably in the Pliocene/Quaternary, based on stratigraphic classification in official geological maps, in order to understand the climatic and tectonic forces occurring during the ongoing accretionary wegde formation. Specifically, we investigate the influence of Quaternary climate variations (Pleistocene cold period, monsoonal variations) on erosional and depositional processes in the (semi)arid Makran as well as local and regional tectonic forces in the Coastal and Central Makran Range region. Necessary for such an analysis is a temporal calibration of alluvial and fluvial terrace sequences that will allow an inter-basin correlation. We utilize the exposure age dating method using terrestrial cosmogenic nuclides (TCN) due to the lack of otherwise datatable material in the arid Makran region. Limited radiocarbon data are only available for marine terraces (wave-cut platforms). Our preliminary 21Ne and 10Be TCN-ages of amalgamated clast samples from (un)deformed terrace and alluvial sequences range from ~250 ky to present day (modern wash). These ages agree in relative terms with sequences previously assigned by other investigations through correlation of Quaternary sequences from Central and Western Iran regions. However, our minimum ages suggest that all age sequences are of middle to late Pleistocene age, compared to Pliocene age estimates previously assigned for the oldest units. Although often suggested, a genetical relation and connection of those fluvial sequences to coastal terraces and wave-cut platforms is problematic due to ambiguous ages and obscured stratigraphic linkage. Our data suggest that events of terrace formation are roughly coeval between basins, but do not indicate a distinct climate forcing, though there is some tendency that terraces were formed during interglacial periods. Preliminary incision rates derived from strath terraces are on the order of 0.1-3 mm/yr with non-steady intervals. This in turn is well in the range of uplift rates deduced from coastal terraces. Further investigations are on the way, especially resolving complex exposure histories based on combining cosmogenic radionuclides and 21Ne.

  17. Valley-fill alluviation during the Little Ice Age (ca. A.D. 1400-1880), Paria River basin and southern Colorado Plateau, United States

    USGS Publications Warehouse

    Hereford, R.

    2002-01-01

    Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tributaries of the Paria River and is largely coincident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern Colorado Plateau. The alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca. A.D. 1200-1400 and 1860-1910, respectively. The fill forms a terrace in the axial valleys of major through-flowing streams. This terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of hillslopes of sparsely vegetated, weakly consolidated bedrock, suggesting that eroded bedrock was an important source of alluvium along with in-channel and other sources. Paleoclimatic and high-resolution paleoflood studies indicate that valley-fill alluviation occured during a long-term decrease in the frequency of large, destructive floods. Aggradation of the valleys ended about A.D. 1880, if not two decades earlier, with the beginning of historic arroyo cutting. This shift from deposition to valley entrenchment near the close of the Little Ice Age generally coincided with the beginning of an episode of the largest floods in the preceding 400-500 yr, which was probably caused by an increased recurrence and intensity of flood-producing El Nin??o events beginning at ca. A.D. 1870.

  18. Regional potentiometric-surface map of the Great Basin carbonate and alluvial aquifer system in Snake Valley and surrounding areas, Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada

    USGS Publications Warehouse

    Gardner, Philip M.; Masbruch, Melissa D.; Plume, Russell W.; Buto, Susan G.

    2011-01-01

    Water-level measurements from 190 wells were used to develop a potentiometric-surface map of the east-central portion of the regional Great Basin carbonate and alluvial aquifer system in and around Snake Valley, eastern Nevada and western Utah. The map area covers approximately 9,000 square miles in Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada. Recent (2007-2010) drilling by the Utah Geological Survey and U.S. Geological Survey has provided new data for areas where water-level measurements were previously unavailable. New water-level data were used to refine mapping of the pathways of intrabasin and interbasin groundwater flow. At 20 of these locations, nested observation wells provide vertical hydraulic gradient data and information related to the degree of connection between basin-fill aquifers and consolidated-rock aquifers. Multiple-year water-level hydrographs are also presented for 32 wells to illustrate the aquifer system's response to interannual climate variations and well withdrawals.

  19. Assessment of the hydrogeochemistry and groundwater quality of the Tarim River Basin in an extreme arid region, NW China.

    PubMed

    Xiao, Jun; Jin, Zhangdong; Wang, Jin

    2014-01-01

    The concentrations of the major and trace elements in the groundwater of the Tarim River Basin (TRB), the largest inland river basin of China, were analyzed before and during rainy seasons to determine the hydrogeochemistry and to assess the groundwater quality for irrigation and drinking purposes. The groundwater within the TRB was slightly alkaline and characterized by high ionic concentrations. The groundwater in the northern sub-basin was fresh water with a Ca(2+)-HCO3(-) water type, whereas the groundwater in the southern and central sub-basins was brackish with a Na(+)-Cl(-) water type. Evaporite dissolution and carbonate weathering were the primary and secondary sources of solutes in the groundwater within the basin, whereas silicate weathering played a minor role. The sodium adsorption ratio (SAR), water quality index (WQI), and sodium percentage (%Na) indicated that the groundwater in the northern sub-basin was suitable for irrigation and drinking, but that in the southern and central sub-basins was not suitable. The groundwater quality was slightly better in the wet season than in the dry season. The groundwater could be used for drinking after treatment for B(3+), F(-), and SO4(2-) and for irrigation after control of the sodium and salinity hazards. Considering the high corrosivity ratio of the groundwater in this area, noncorrosive pipes should be used for the groundwater supply. For sustainable development, integrated management of the surface water and the groundwater is needed in the future. PMID:24221557

  20. Assessment of the Hydrogeochemistry and Groundwater Quality of the Tarim River Basin in an Extreme Arid Region, NW China

    NASA Astrophysics Data System (ADS)

    Xiao, Jun; Jin, Zhangdong; Wang, Jin

    2014-01-01

    The concentrations of the major and trace elements in the groundwater of the Tarim River Basin (TRB), the largest inland river basin of China, were analyzed before and during rainy seasons to determine the hydrogeochemistry and to assess the groundwater quality for irrigation and drinking purposes. The groundwater within the TRB was slightly alkaline and characterized by high ionic concentrations. The groundwater in the northern sub-basin was fresh water with a Ca2+-HCO3 - water type, whereas the groundwater in the southern and central sub-basins was brackish with a Na+-Cl- water type. Evaporite dissolution and carbonate weathering were the primary and secondary sources of solutes in the groundwater within the basin, whereas silicate weathering played a minor role. The sodium adsorption ratio (SAR), water quality index (WQI), and sodium percentage (%Na) indicated that the groundwater in the northern sub-basin was suitable for irrigation and drinking, but that in the southern and central sub-basins was not suitable. The groundwater quality was slightly better in the wet season than in the dry season. The groundwater could be used for drinking after treatment for B3+, F-, and SO4 2- and for irrigation after control of the sodium and salinity hazards. Considering the high corrosivity ratio of the groundwater in this area, noncorrosive pipes should be used for the groundwater supply. For sustainable development, integrated management of the surface water and the groundwater is needed in the future.

  1. Study of crop coefficient and the ratio of soil evaporation to evapotranspiration in an irrigated maize field in an arid area of Yellow River Basin in China

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan; Yan, Haofang; Shi, Haibin; Sugimoto, Hideki

    2013-08-01

    A field experiment was conducted in a maize field in 2006 in an arid area of the Yellow River Basin in China. The daytime evapotranspiration (ETc) and soil evaporation beneath the maize canopy ( E g) were measured by Bowen ratio energy balance method and micro-lysimeters, respectively. The results showed that the total ETc during maize growth season was 696 mm, and the maximum values occurred at about 90-140 days after sowing. The crop coefficient ( K c), which was calculated from the ratio of ETc to reference evapotranspiration (ET0), was quite different from the values reported by other researchers in similar climate areas, with average values of 0.34, 0.47, 1.0 and 0.9 for initial, development, mid-season and late-season stages, respectively. High correlations between leaf area index (LAI) and average K c for every 4 days were obtained. The total E g was 201.4 mm with average values ranged from 0.92 to 2.05 for four growth stages of maize; and accounted for around 28.9 % of ETc. The ratio E g/ETc showed high negative relationship with LAI. These results were very important in precise management of irrigation for maize in Yellow River Basin areas.

  2. The problems of overexploitation of aquifers in semi-arid areas: the Murcia Region and the Segura Basin (South-east Spain) case

    NASA Astrophysics Data System (ADS)

    Rodríguez-Estrella, T.

    2012-05-01

    A general analysis of the problems arising from aquifer exploitation in semi-arid areas such as the Autonomous Region of Murcia, which belongs to the Segura Basin is presented, with particular reference to the Ascoy-Sopalmo aquifer, which is the most overexploited aquifer in Spain. It has suffered intense overabstraction over the last forty years, given renewable water resources of 2 Mm3 yr-1 and abstractions amounting to as much as 55 Mm3 yr-1. This has resulted in the drying of springs, continuous drawdown of water levels (5 m yr-1); piezometric drops (over 30 m in one year, as a consequence of it being a karstic aquifer); increase in pumping costs (elevating water from more than 320 m depth); abandoning of wells (45 reduced to 20), diminishing groundwater reserves, and deteriorating water quality (progressing from a mixed sodium bicarbonate-chloride facies to a sodium chloride one). This is a prime example of poor management with disastrous consequences. In this sense, a series of internal measures is proposed to alleviate the overexploitation of this aquifer and of the Segura Basin, with the aim of contributing to a sustainable future.

  3. Responses of surface runoff to climate change and human activities in the arid region of central Asia: a case study in the Tarim River basin, China.

    PubMed

    Xu, Changchun; Chen, Yaning; Chen, Yapeng; Zhao, Ruifeng; Ding, Hui

    2013-04-01

    Based on hydrological and climatic data and land use/cover change data covering the period from 1957 to 2009, this paper investigates the hydrological responses to climate change and to human activities in the arid Tarim River basin (TRB). The results show that the surface runoff of three headstreams (Aksu River, Yarkant River and Hotan River) of the Tarim River exhibited a significant increasing trend since 1960s and entered an even higher-runoff stage in 1994. In the contrary, the surface runoff of Tarim mainstream displayed a persistent decreasing trend since 1960s. The increasing trend of surface runoff in the headstreams can be attributed to the combined effects of both temperature and precipitation changes during the past five decades. But, the decreasing trend of surface runoff in the mainstream and the observed alterations of the temporal and spatial distribution patterns were mainly due to the adverse impacts of human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff in the mainstream. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches. It is now unequivocally clear that water-use conflicts among different sectors and water-use competitions between upper and lower reaches are approaching to dangerous levels in TRB that is thus crying for implementing an integrated river basin management scheme. PMID:23377191

  4. Responses of Surface Runoff to Climate Change and Human Activities in the Arid Region of Central Asia: A Case Study in the Tarim River Basin, China

    NASA Astrophysics Data System (ADS)

    Xu, Changchun; Chen, Yaning; Chen, Yapeng; Zhao, Ruifeng; Ding, Hui

    2013-04-01

    Based on hydrological and climatic data and land use/cover change data covering the period from 1957 to 2009, this paper investigates the hydrological responses to climate change and to human activities in the arid Tarim River basin (TRB). The results show that the surface runoff of three headstreams (Aksu River, Yarkant River and Hotan River) of the Tarim River exhibited a significant increasing trend since 1960s and entered an even higher-runoff stage in 1994. In the contrary, the surface runoff of Tarim mainstream displayed a persistent decreasing trend since 1960s. The increasing trend of surface runoff in the headstreams can be attributed to the combined effects of both temperature and precipitation changes during the past five decades. But, the decreasing trend of surface runoff in the mainstream and the observed alterations of the temporal and spatial distribution patterns were mainly due to the adverse impacts of human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff in the mainstream. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches. It is now unequivocally clear that water-use conflicts among different sectors and water-use competitions between upper and lower reaches are approaching to dangerous levels in TRB that is thus crying for implementing an integrated river basin management scheme.

  5. Using geochemical investigations for determining the interaction between groundwater and saline water in arid areas: case of the Wadi Ouazzi basin (Morocco)

    NASA Astrophysics Data System (ADS)

    El Moukhayar, R.; Bahir, M.; Youbi, N.; Chkir, N.; Chamchati, H.; Caréra, P.

    2015-04-01

    The characteristics of the Essaouira basin water resources are a semi-arid climate, which is severely impacted by the climate (quantity and quality). Considering the importance of the Essaouira aquifer in the groundwater supply of the region, a study was conducted in order to understand groundwater evolution in this aquifer. The Essaouira aquifer is a coastal aquifer located on the Atlantic coastline of southern Morocco, corresponding to a sedimentary basin with an area of nearly 200 km2. The control of the fluid exchange and the influence of mixing zones between the groundwater and saline water was investigated by sampling from 20 wells, drillings and sources belonging to the Plio-Quaternary and Turonian aquifers. It is hypothesized that groundwater major ions chemistry can be employed to determine the interaction between the groundwater and saline water (coastal aquifers). Groundwater samples examined for electric conductivity and temperature showed that waters belonging to the Plio-Quaternary and Turonian aquifers present very variable electric conductivities, from 900 ?s/cm to 3880 ?s/cm. Despite this variability, they are from the same family and are characterized by sodium-chloride facies. However, a good correlation exists between the electrical conductivity and chloride and sodium contents. The lower electrical conductivities are situated in the North quarter immediately to the south of the Wadi Ouazzi.

  6. Linking the End of Glaciation in Gondwana to Aridity in the Tropics: Coupled Sr Chemostratigraphy and Cyclostratigraphy From the Permian Basin, Texas

    NASA Astrophysics Data System (ADS)

    Rasbury, E. T.; Hemming, N. G.; Saller, A. H.; Dickson, J.

    2007-05-01

    Crowell (1978) suggested the Earth was poised on the brink of glaciation throughout the Paleozoic and that closure of the low-latitude seaway between North America and Europe was responsible for diversion of moisture- laden currents to the south to feed the long-lived Carboniferous-Permian glaciers. This same diversion of currents also produced dramatic aridity in the tropics. This is seen in changes in paleosol types as well as in widespread loess and erg deposits. It also coincides with a dramatic decline in Sr isotopes across the Carboniferous-Permian boundary. Sr chemostratigraphy from cores taken across this boundary on the Central Basin Platform (CBP) of the Permian Basin in Texas show the same dramatic shift as seen in data from the type sections in the Urals across this boundary. This confirms that the fusulinid based stage boundaries for the Permian Basin are correct. On the CBP, high-frequency high-amplitude cycles end at a major stepback of the shelf margin at Abo/Clearfork time (Sakmarian). We suggest this transgression represents the end of major Gondwanan glaciation. If we assume the decline in 87Sr/86Sr is reflecting the aridity of the topics and calculate the reduction in continental Sr flux to the oceans, we can relate this to decreased silicate weathering and the consequent increase in atmospheric CO2. Assuming crustal values of [Sr] of 350 ppm, congruent weathering, that the total number of moles of Sr in the ocean is the same as today, and that all of the change is due to a change in flux of Sr from the continents, the change from a late Carboniferous 87Sr/86Sr high of 0.7082 to a value of 0.7078 (the end of cyclothems), equates to an increase in the ocean-atmosphere system of approximately 4 * 106 gigatons of carbon. Preindustrial carbon concentration in the atmosphere is estimated at 578 gigatons. Obviously there are feedbacks that will remove some of the carbon from the ocean-atmosphere system, perhaps to the biosphere, but this simple calculation shows that no special circumstances are needed to account for the increase in pCO2 shown by published proxy data. It also demonstrates why a model that only considers tectonic changes might fail to reproduce this part of the Sr curve. However, the 87Sr/86Sr continues to decrease to a late Permian low of 0.7069 without reversal while the proxy data show a decrease in pCO2 in the middle Permian to near Carboniferous values. Nevertheless, the change is coincident with a flattening in the most recently published Permian Sr curve.

  7. Bedload transport in alluvial channels

    USGS Publications Warehouse

    Bravo-Espinosa, M.; Osterkamp, W.R.; Lopes, V.L.

    2003-01-01

    Hydraulic, sediment, land-use, and rock-erosivity data of 22 alluvial streams were used to evaluate conditions of bedload transport and the performance of selected bedload-transport equations. Transport categories of transport-limited (TL), partially transport-limited (PTL), and supply-limited (SL) were identified by a semiquantitative approach that considers hydraulic constraints on sediment movement and the processes that control sediment availability at the basin scale. Equations by Parker et al. in 1982, Schoklitsch in 1962, and Meyer-Peter and Muller in 1948 adequately predicted sediment transport in channels with TL condition, whereas the equations of Bagnold in 1980, and Schoklitsch, in 1962, performed well for PTL and SL conditions. Overall, the equation of Schoklitsch predicted well the measured bedload data for eight of 22 streams, and the Bagnold equation predicted the measured data in seven streams.

  8. Restoring the Mississippi River Basin from the Catchment to the Coast Defines Science and Policy Issues of Ecosystem Services Associated with Alluvial and Coastal Deltaic Floodplains: Soil Conservation, Nutrient Reduction, Carbon Sequestration, and Flood Control

    NASA Astrophysics Data System (ADS)

    Twilley, R.

    2014-12-01

    Large river systems are major economic engines that provide national economic wealth in transporting commerce and providing extensive agriculture production, and their coastal deltas are sites of significant ports, energy resources and fisheries. These coupled natural and social systems from the catchment to the coast depend on how national policies manage the river basins that they depend. The fundamental principle of the Mississippi River Basin, as in all basins, is to capitalize on the ability of fertile soil that moves from erosional regions of a large watershed, through downstream regions of the catchment where sediment transport and storage builds extensive floodplains, to the coastal region of deposition where deltas capture sediment and nutrients before exported to the oceans. The fate of soil, and the ability of that soil to do work, supports the goods and services along its path from the catchment to the coast in all large river basin and delta systems. Sediment is the commodity of all large river basin systems that together with the seasonal pulse of floods across the interior of continents provide access to the sea forming the assets that civilization and economic engines have tapped to build national and global wealth. Coastal landscapes represent some of the most altered ecosystems worldwide and often integrate the effects of processes over their entire catchment, requiring systemic solutions to achieve restoration goals from alluvial floodplains upstream to coastal deltaic floodplains downstream. The urgent need for wetland rehabilitation at landscape scales has been initiated through major floodplain reclamation and hydrologic diversions to reconnect the river with wetland processes. But the constraints of sediment delivery and nutrient enrichment represent some critical conflicts in earth surface processes that limit the ability to design 'self sustaining' public work projects; particularly with the challenges of accelerated sea level rise. Only through rethinking how we manage the Mississippi River not only to provide for navigation and flood control, but also as the critical source of sediments to stabilize degrading wetlands, will restoration be realized in a 100-year project cycle.

  9. REACH SPECIFIC CHANNEL STABILIZATION BASED ON COMPREHENSIVE EVALUATION OF VALLEY FILL HISTORY, ALLUVIAL ARCHITECTURE AND GROUNDWATER HYDROLOGY IN A MOUNTAIN STREAM IN THE CENTRAL GREAT BASIN, NEVADA

    EPA Science Inventory

    Kingston meadow, located in the Toiyabe Range, is one of many wet meadow complexes threatened by rapid channel incision in the mountain ranges of the central Great Basin. Channel incision can lower the baselevel for groundwater discharge and de-water meadow complexes resulting in...

  10. Tectonic and climatic control on geomorphological and sedimentary evolution of the Mercure basin, southern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Robustelli, Gaetano; Ermolli, Elda Russo; Petrosino, Paola; Jicha, Brian; Sardella, Raffaele; Donato, Paola

    2014-06-01

    The morpho-tectonic and sedimentary evolution of the Mercure intramontane basin (Calabria-Lucania boundary, southern Apennines) has been assessed through facies analysis, morphostratigraphy and geomorphological correlation with adjacent areas. The Mercure basin, one of the most active seismogenic zones of the southern Apennines, is a favorable area for reconstructing the main stages of landscape evolution of the axial zone because of its capability to record changes in base level during the Quaternary. In addition, the presence of both erosional and depositional Palaeosurfaces is a useful marker for reconstructing tectonic and morphogenetic events, and hence to detect the role played by tectonics and climate in its genesis, evolution and extinction. The present study identifies the key role of tectonics and denudation, combined with high-frequency floods, as mechanisms controlling alluvial sedimentation in the study area. During endorheic conditions, denudational processes driven by pulses of extensional deformation of the basin margin caused strong alluvial inputs that resulted in the development of alluvial fans. Alluvial facies are mainly characterized by turbulent, subaerial, hyperconcentrated flood flows deposited during the glacial, semi-arid conditions of MIS 14. The retrogradational stacking pattern of the alluvial system indicates decreasing rates of tectonic activity along with declining river gradients. The Mercure coalescing alluvial fans were inundated by lake transgression during MIS 13 in response to (i) abrupt tectonic subsidence at the basin margins and (ii) large decrease of coarse sediment supply due to the interplay among climate, tectonics and catchment size changes. In this regard, it is suggested that tectonic control on the drainage network along with climate and long-term slope evolution may have caused marked pulses in sediment supply, thus influencing the arrangement of facies associations in the sedimentary succession. In addition, the study points out that the main tectonic landforms developed during each period of the landscape evolution well correspond with some active fault segments.

  11. The implications of geology, soils, and vegetation on landscape morphology: Inferences from semi-arid basins with complex vegetation patterns in Central New Mexico, USA

    NASA Astrophysics Data System (ADS)

    Yetemen, Omer; Istanbulluoglu, Erkan; Vivoni, Enrique R.

    2010-04-01

    This paper examines the relationship between land surface properties (e.g. soil, vegetation, and lithology) and landscape morphology quantified by the catchment descriptors: the slope-area (S-A) relation, curvature-area (C-A) relation, and the cumulative area distribution (CAD), in two semi-arid basins in central New Mexico. The first site is composed of several basins located in today's desert elevations with mesic north-facing and xeric south-facing hillslopes underlain by different lithological formations. The second site is a mountainous basin exhibiting vegetation gradients from shrublands in the lower elevations to grasslands and forests at higher elevations. All three land surface properties were found to have significant influences on the S-A and C- A relations, while the power-law exponents of the CADs for these properties did not show any significant deviations from the narrow range of universal scaling exponents reported in the literature. Among the three different surface properties we investigated, vegetation had the most profound impact on the catchment descriptors. In the S-A diagrams of the aspect-controlled ecosystems, we found steeper slopes in north-facing aspects than south-facing aspects for a given drainage area. In elevation-controlled ecosystems, forested landscapes exhibited the steepest slopes for the range of drainage areas examined, followed by shrublands and grasslands in all soil textures and lithologies. In the C-A diagrams, steeper slopes led to a higher degree of divergence on hillslopes and a higher degree of convergence in the valleys than shallower slopes. The influence of functional types of vegetation detected on observed topography provided some initial understanding of the potential impacts of life on the organization of topography. This finding also emphasizes the critical role of climate in catchment development. We suggest that climatic fluctuations that are capable of replacing vegetation communities could lead to highly amplified hydrological and geomorphic responses.

  12. Assimilation of Gridded Snow Water Equivalent and Satellite Snowcover Products for Semi- arid Mountain Basins in a Hydrologic Model

    NASA Astrophysics Data System (ADS)

    Dressler, K. A.; Moradkhani, H.

    2006-12-01

    This study examines the Particle Filter (PF) assimilation technique for distributed estimates of snow covered area (SCA) and snow-water equivalent (SWE) to update hydrologic model states. PF is a class of Bayesian filtering algorithms derived from a discrete description of Bayes rule well-suited for updating the nonlinear model states, resulting in improved model outputs. Assimilation runs are applied to the USGS Precipitation Runoff Modeling System (PRMS) hydrologic model using 1-km2 SCA derived from NOAA Advanced Very High Resolution Radiometer imagery and 1-km2 SWE estimates interpolated from National Resources Conservation Service Snow Telemetry (SNOTEL) point measurements for a six-year period (1995-2000). Two headwater basins within the Rio Grande (i.e. upper Rio Grande River basin) and Salt River (i.e. Black River basin) drainages in the Southwestern United States are contrasted. Base runs indicate measured SCA and SWE estimates were consistently lower than values estimated from temperature and precipitation within PRMS. The greatest differences occurred in the relatively complex terrain of the Rio Grande basin, as opposed to the relatively homogeneous terrain of the Black River basin, where differences were small. Differences between modeled and measured snow were different for the accumulation period versus the ablation period and had an elevational trend. Direct insertion of measured snowfields into a version of PRMS calibrated to achieve water balance led to reduced performance in estimating streamflow for the Rio Grande and increased performance in estimating streamflow for the Black River basin. However, PF as a sequential Monte Carlo technique is able to take the most advantage of information content in the data which relaxes the need for restrictive assumptions in direct insertion and even other assimilation techniques. Therefore, in this study we demonstrate the features of such a filtering technique with the potential to estimate the uncertainty of updated SCA and SWE in an ensemble framework.

  13. Project 5322 Mid-Term Report: Key Eco-Hydrological Parameters Retrieval And Land Data Assimilation System Development In A Typical Inland River Basin Of Chinas Arid Region

    NASA Astrophysics Data System (ADS)

    Faivre, R.; Colin, J.; Menenti, M.; Lindenbergh, R.; Van Den Bergh, L.; Yu, H.; Jia, L.; Xin, L.

    2010-10-01

    Improving the understanding and the monitoring of high elevation regions hydrology is of major relevance from both societal and environmental points of view for many Asian countries, in particular in terms of flood and drought, but also in terms of food security in a chang- ing environment. Satellite and airborne remote sensing technologies are of utmost for such a challenge. Exist- ing imaging spectro-radiometers, radars, microwave ra- diometers and backscatter LIDAR provide a very com- prehensive suite of measurements over a wide rage of wavelengths, time frequencies and spatial resolu- tions. It is however needed to devise new algorithms to convert these radiometric measurements into useful eco-hydrological quantitative parameters for hydrologi- cal modeling and water management. The DRAGON II project entitled Key Eco-Hydrological Parameters Re- trieval and Land Data Assimilation System Development in a Typical Inland River Basin of Chinas Arid Region (ID 5322) aims at improving the monitoring, understand- ing, and predictability of hydrological and ecological pro- cesses at catchment scale, and promote the applicability of quantitative remote sensing in watershed science. Ex- isting Earth Observation platforms provided by the Euro- pean Space Agency as well as prototype airborne systems developed in China - ENVISAT/AATSR, ALOS/PRISM and PALSAR, Airborne LIDAR - are used and combined to retrieve advanced land surface physical properties over high elevation arid regions of China. The existing syn- ergies between this project, the CEOP-AEGIS project (FP7) and the WATER project (CAS) provide incentives for innovative studies. The investigations presented in the following report focus on the development of advanced and innovative methodologies and algorithms to monitor both the state and the trend of key eco-hydrological vari- ables: 3D vegetation properties, land surface evaporation, glacier mass balance and drought indicators.

  14. Volcanic-sedimentary features in the Serra Geral Fm., Paraná Basin, southern Brazil: Examples of dynamic lava-sediment interactions in an arid setting

    NASA Astrophysics Data System (ADS)

    Petry, Karla; Jerram, Dougal A.; de Almeida, Delia del Pilar M.; Zerfass, Henrique

    2007-01-01

    The formation of volcanic-sedimentary interaction features in extreme arid environments is not a commonly described process. Specifically the occurrence of dynamically mixed sediments and juvenile igneous clasts as peperites, for water has been considered one major important factor in the processes of magma dismantling and mingling with unconsolidated sediment to form such deposits. The study area, located in south Brazil, shows a sequence of lava flows and intertrapic sandstone layers from the Paraná Basin, associated with the formation of clastic dykes, flow striations, peperite and 'peperite-like' breccias. Four processes are suggested for the genesis of the peperites: (a) fragmentation of the flow front and base; (b) sand injection; (c) dune collapse; (d) magma cascade downhill. The continued flow of a lava, while its outer crust is already cooling, causes it to break, especially in the front and base, fragments falling in the sand and getting mixed with it, generating the flow front 'peperite-like' breccia. The weight of the lava flow associated to shear stress at the base cause sand to be injected inwards the flow, forming injection clastic dykes in the cooled parts and injection peperite in the more plastic portions. The lava flow may partially erode the dune, causing the dune to collapse and forming the collapse 'peperite-like' breccia. The shear stress at the base of a flowing lava striates the unconsolidated sand, forming the flow striations. The sand that migrates over a cooled, jointed lava flow may get caught in the cavities and joints, forming the filling clastic dykes. These deposits are analogous to those found in the Etendeka, NW Namibia, and show that sediment-lava interactions in arid settings are widespread throughout the Paraná-Etendeka province during the onset of flood volcanism.

  15. Analysis of trends and changes in the water environment of an inland river basin in an arid area.

    PubMed

    Li, Wei H; Fu, Ai H; Zhou, Hong H; Zhu, Cheng G; Aji, Dilinuer

    2014-02-01

    Lake Bosten is the largest inland freshwater lake in China and plays a key role in the local arid-area ecosystem. This study focuses on the dynamics of water salinity of Lake Bosten in the past 55 years (1955-2009) and intends to quantify the associations between the water salinity and the magnitudes of water level, inflow, outflow, total wastewater drainage into the lake, including industrial and residential wastewater. Correlation analysis reveals that the water salinity has strong associations with those six factors (R = -0.810, -0.510, -0.844, 0.903, 0.855, and 0.685, respectively). We predict that water level, inflow and water salinity of Lake Bosten will decline in 2010-2019. This study recommends a reduction in salt input to the Bosten River by reducing industrial wastewater discharge along the river and the development of clean production technology. PMID:24645540

  16. Indication of Stable Isotope Composition on the Process of Oasification and Desertification in Arid Regions: A Case Study in the Heihe River Basin

    NASA Astrophysics Data System (ADS)

    Ma, J. Y.; Zeng, Q.

    2014-12-01

    Oasification and desertification are the two main land surface processes contrarily correlated with each other in arid regions. It is useful for environmental indication research to clarify the relationship between plants and environment under the oasification and desertification processes in arid regions. In the Heihe River basin, the most representative areas of oasification and desertification in China, we carried out a study to test whether or not we can use plant and soil stable isotope signature as an indicator of changes in key land surface process. Stable carbon (?13C) of plant leaves, hydrogen (?D) and oxygen (?18O) isotopes of plant stem water and potential water sources were analyzed to investigate the water use efficiency (WUE) and water sources of different plant species in three typical habitats (oasis, oasis-desert transitional zone, desert). The results suggest that plants in the desert habitat tended to use water from deeper soil layer (>160 cm). In the oasis-desert transitional zone, Artimisia arenaria and Calligonum mongolicum were likely used water mainly from the soil layer about 20-40 cm in depth, Haloxylon ammodendron utilized water primarily from 60-80 cm in depth, Hedysarum scoparium may use water from soil layer about 100 cm in depth and Tamarix ramosissima obtained its water from deeper soil layer(>120 cm). Plants in the oasis habitat used soil water mainly from 0 to 100 cm soil layers. Calamagrostis pseudophragmites used water about 20 cm in depth, Zea mays extracted soil water from the depth of 20-40 cm, and Tamarix ramosissima and Populus simonii obtained soil water about 60 cm in depth. The ?13C values of C3 plants in each habitat differed significantly. In the oasis zone, WUE of shrubs were more positive than this of grass, which were similar to the conclusions of the previous studies. Among the three habitats, plants in oasis-desert transitional zone had the most positive ?13C values whereas plants in oasis area had the most negative values. This pattern may have resulted from soil texture, soil water content and plant water sources differences among the habitats. Overall, the results of our study illustrated that plant and soil isotope composition are useful for the indication of the processes of oasification and desertification in arid regions.

  17. Hydraulic Modeling of Alluvial Fans along the Truckee Canal using the 2-Dimensional Model SRH2D

    NASA Astrophysics Data System (ADS)

    Wright, J.; Kallio, R.; Sankovich, V.

    2013-12-01

    Alluvial fans are gently sloping, fan-shaped landforms created by sediment deposition at the ends of mountain valleys. Their gentle slopes and scenic vistas are attractive to developers. Unfortunately, alluvial fans are highly flood-prone, and the flow paths of flood events are highly variable, thereby placing human developments at risk. Many studies have been performed on alluvial fans in the arid west because of the uncertainty of their flow paths and flood extents. Most of these studies have been focused on flood elevations and mitigation. This study is not focused on the flood elevations. Rather, it is focused on the attenuation effects of alluvial fans on floods entering and potentially failing a Reclamation canal. The Truckee Canal diverts water from the Truckee River to Lahontan Reservoir. The drainage areas along the canal are alluvial fans with complex distributary channel networks . Ideally, in nature, the sediment grain-size distribution along the alluvial fan flow paths would provide enough infiltration and subsurface storage to attenuate floods entering the canal and reduce risk to low levels. Human development, however, can prevent the natural losses from occurring due to concentrated flows within the alluvial fan. While the concentrated flows might mitigate flood risk inside the fan, they do not lower the flood risk of the canal. A 2-dimensional hydraulic model, SRH-2D, was coupled to a 1-dimensional rainfall-runoff model to estimate the flood attenuation effects of the alluvial fan network surrounding an 11 mile stretch of the Truckee Canal near Fernley, Nevada. Floods having annual exceedance probabilities ranging from 1/10 to 1/100 were computed and analyzed. SRH-2D uses a zonal approach for modeling river systems, allowing areas to be divided into separate zones based on physical parameters such as surface roughness and infiltration. One of the major features of SRH-2D is the adoption of an unstructured hybrid mixed element mesh, which is based on the arbitrarily shared element method for geometric representation. The flexibility of the mesh generation allowed the complex alluvial network of incised channels to be modeled in greater detail. The SRH-2D model was modified to allow for Green-Ampt infiltration losses, thus producing more accurate characterization of the alluvial fan process where such losses can be significant. The SRH-2D model was built using a LiDAR based terrain grid, and the assumed channel mesh was refined using a geologic map. Water conveyance was modeled to coincide with the young geologic unit . By developing lateral inflow hydrographs using the SRH-2D model, a more accurate risk assessment was achieved. Model results show basins without human development have the highest flood attenuation, and development tends to concentrate channel flows. The SRH-2D model improved Reclamation's understanding of flood flows entering the Truckee Canal from alluvial fans.

  18. Alluvial Fan in Icaria Planum, Mars

    NASA Astrophysics Data System (ADS)

    Korteniemi, J.; Raitala, J.; Aittola, M.; Kostama, V.; Hauber, E.; Kronberg, P.; Neukum, G.; HRSC Co-I Team

    2005-12-01

    The Mars Express HRSC data were used to study fluvial history of southern Claritas on Mars (1, 2). Volatiles, transported downslope to the basin, breached through a saddle valley and formed a channel towards Icaria Planum in the west. Along the channel, sapping provided additional water. The channel broke into a 30-km impact crater and formed a temporary lake. The crater rim has terraces and the floor has smooth deposits. A delta was formed in a standing water. After breaching the crater rim through a neck which is higher than the crater floor, water deposited onto Icaria Planum an alluvial fan. This fan was studied using the HRSC colour data by mapping deposit units of the Icaria lowlands in front of the channel. The flood deposits were made visible by the multichannel HRSC data classification. The alluvial structures reflect topography and regional slopes as well as the amount of available water. The hi-resolution HRSC image provides an additional view into the alluvial structures, erosion and sedimentation in the channel formation. These remote sensing approaches facilitate the mapping of characteristic phases in the fluvial development of the area studied. References. (1) Raitala et al., 2005. LPS XXXVI, #1307. (2) Korteniemi, J., Raitala, J., Aittola, M., Kostama V.-P., Hauber E., Kronberg P., Neukum G. and the HRSC Co-I Team, 2005. Fluvial channel resulted in alluvial fan formation in Icaria Planum, Mars. Submitted to 42nd Vernadsky-Brown Microsymposium, Moscow 9-12. 10. 2005.

  19. Morphogenesis and grain size variation of alluvial gold recovered in auriferous sediments of the Tormes Basin (Iberian Peninsula) using a simple correspondence analysis

    NASA Astrophysics Data System (ADS)

    Barrios, S.; Merinero, R.; Lozano, R.; Orea, I.

    2015-07-01

    With present techniques it is difficult to determine whether the gold particles present at fluvial placers have come from one or multiple sources. Knowledge of this would be useful in prospecting for larger gold deposits. The aim of the present work was to test the potential of a technique based on modern visual and classic statistical methods to determine the single or multisource origin of gold particles at different sites in the Tormes Basin (Central Iberian Zone of the Iberian Massif, Iberian Peninsula). This basin contains numerous lode and placer gold deposits that have been exploited since ancient times. Today, gold nuggets (usually associated with quartz, 0.2-6 g in weight, 0.53-3.74 cm long and mostly discoidal in shape and of intermediate roundness) can be recovered from the sediments of the upper reaches of the River Tormes. These nuggets, as well as small gold particles collected at three gravel pits from across the basin (all of which showed abrasion marks) were examined by optical and/or environmental scanning electron microscopy, and the differences in their dimensions and morphological features noted. Simple correspondence analysis of the sphericity and roundness of the nuggets and particles was used to morphologically classify the gold samples collected at each location. The gold nuggets were best classified as elongated rods of intermediate roundness. Surprisingly, the gold particles from the most upstream and downstream gravel pits were best described as discs/sub-discs of rounded appearance, while those from the intermediate gravel pit were discs of intermediate roundness. Analysis of the variance followed by the Tukey honest significant differences test revealed the particles from the most upstream gravel pit to be significantly more flattened and smaller. These were therefore transported further from their source than the particles collected at the other two pits. These results suggest that multiple sources of sedimentary gold exist in the Tormes Basin and that these feed these different gravel pits. Present techniques for classifying gold would not have detected these differences.

  20. Morphogenesis and grain size variation of alluvial gold recovered in auriferous sediments of the Tormes Basin (Iberian Peninsula) using a simple correspondence analysis

    NASA Astrophysics Data System (ADS)

    Barrios, S.; Merinero, R.; Lozano, R.; Orea, I.

    2015-12-01

    With present techniques it is difficult to determine whether the gold particles present at fluvial placers have come from one or multiple sources. Knowledge of this would be useful in prospecting for larger gold deposits. The aim of the present work was to test the potential of a technique based on modern visual and classic statistical methods to determine the single or multisource origin of gold particles at different sites in the Tormes Basin (Central Iberian Zone of the Iberian Massif, Iberian Peninsula). This basin contains numerous lode and placer gold deposits that have been exploited since ancient times. Today, gold nuggets (usually associated with quartz, 0.2-6 g in weight, 0.53-3.74 cm long and mostly discoidal in shape and of intermediate roundness) can be recovered from the sediments of the upper reaches of the River Tormes. These nuggets, as well as small gold particles collected at three gravel pits from across the basin (all of which showed abrasion marks) were examined by optical and/or environmental scanning electron microscopy, and the differences in their dimensions and morphological features noted. Simple correspondence analysis of the sphericity and roundness of the nuggets and particles was used to morphologically classify the gold samples collected at each location. The gold nuggets were best classified as elongated rods of intermediate roundness. Surprisingly, the gold particles from the most upstream and downstream gravel pits were best described as discs/sub-discs of rounded appearance, while those from the intermediate gravel pit were discs of intermediate roundness. Analysis of the variance followed by the Tukey honest significant differences test revealed the particles from the most upstream gravel pit to be significantly more flattened and smaller. These were therefore transported further from their source than the particles collected at the other two pits. These results suggest that multiple sources of sedimentary gold exist in the Tormes Basin and that these feed these different gravel pits. Present techniques for classifying gold would not have detected these differences.

  1. Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia.

    PubMed

    Beyer, Matthias; Gaj, Marcel; Hamutoko, Josefina Tulimeveva; Koeniger, Paul; Wanke, Heike; Himmelsbach, Thomas

    2015-12-01

    The stable water isotope deuterium ((2)H) was applied as an artificial tracer ((2)H2O) in order to estimate groundwater recharge through the unsaturated zone and describe soil water movement in a semi-arid region of northern central Namibia. A particular focus of this study was to assess the spatiotemporal persistence of the tracer when applied in the field on a small scale under extreme climatic conditions and to propose a method to obtain estimates of recharge in data-scarce regions. At two natural sites that differ in vegetation cover, soil and geology, 500?ml of a 70?% (2)H2O solution was irrigated onto water saturated plots. The displacement of the (2)H peak was analyzed 1 and 10 days after an artificial rain event of 20 mm as well as after the rainy season. Results show that it is possible to apply the peak displacement method for the estimation of groundwater recharge rates in semi-arid environments via deuterium labelling. Potential recharge for the rainy season 2013/2014 was calculated as 45 mm a(-1) at 5.6 m depth and 40 mm a(-1) at 0.9 m depth at the two studied sites, respectively. Under saturated conditions, the artificial rain events moved 2.1 and 0.5 m downwards, respectively. The tracer at the deep sand site (site 1) was found after the rainy season at 5.6 m depth, corresponding to a displacement of 3.2 m. This equals in an average travel velocity of 2.8 cm d(-1) during the rainy season at the first site. At the second location, the tracer peak was discovered at 0.9 m depth; displacement was found to be only 0.4 m equalling an average movement of 0.2 cm d(-1) through the unsaturated zone due to an underlying calcrete formation. Tracer recovery after one rainy season was found to be as low as 3.6?% at site 1 and 1.9?% at site 2. With an in situ measuring technique, a three-dimensional distribution of (2)H after the rainy season could be measured and visualized. This study comprises the first application of the peak displacement method using a deuterium labelling technique for the estimation of groundwater recharge in semi-arid regions. Deuterium proved to be a suitable tracer for studies within the soil-vegetation-atmosphere interface. The results of this study are relevant for the design of labelling experiments in the unsaturated zone of dry areas using (2)H2O as a tracer and obtaining estimations of groundwater recharge on a local scale. The presented methodology is particularly beneficial in data-scarce environments, where recharge pathways and mechanisms are poorly understood. PMID:26414647

  2. Attribution of satellite-observed vegetation trends in a hyper-arid region of the Heihe River basin, Western China

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Roderick, M. L.; Shen, Y.; Sun, F.

    2014-09-01

    Terrestrial vegetation dynamics are closely influenced by both climate and by both climate and by land use and/or land cover change (LULCC) caused by human activities. Both can change over time in a monotonic way and it can be difficult to separate the effects of climate change from LULCC on vegetation. Here we attempt to attribute trends in the fractional green vegetation cover to climate variability and to human activity in Ejina Region, a hyper-arid landlocked region in northwest China. This region is dominated by extensive deserts with relatively small areas of irrigation located along the major water courses as is typical throughout much of Central Asia. Variations of fractional vegetation cover from 2000 to 2012 were determined using Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index data with 250 m spatial resolution over 16-day intervals. We found that the fractional vegetation cover in this hyper-arid region is very low but that the mean growing season vegetation cover has increased from 3.4% in 2000 to 4.5% in 2012. The largest contribution to the overall greening was due to changes in green vegetation cover of the extensive desert areas with a smaller contribution due to changes in the area of irrigated land. Comprehensive analysis with different precipitation data sources found that the greening of the desert was associated with increases in regional precipitation. We further report that the area of land irrigated each year can be predicted using the runoff gauged 1 year earlier. Taken together, water availability both from precipitation in the desert and runoff inflow for the irrigation agricultural lands can explain at least 52% of the total variance in regional vegetation cover from 2000 to 2010. The results demonstrate that it is possible to separate the satellite-observed changes in green vegetation cover into components due to climate and human modifications. Such results inform management on the implications for water allocation between oases in the middle and lower reaches and for water management in the Ejina oasis.

  3. Hydrological and land-use controls of watershed exports of DOM and nutrients in a large arid river basin of Western China

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Lu, Y.; Edmonds, J. W.; Zheng, C.; Wang, S.

    2014-12-01

    The Heihe River Basin (HRB) is the second largest inland river basin in arid Western China. The Heihe river has been significantly modified to make human settlements possible, particularly involving regulating water flow and extracting groundwater to support irrigated agriculture. It remains unknown how these engineered modifications alter transfers of carbon and nutrients from the watersheds to the river. We sampled surface water and groundwater in the middle reach of the HRB during contrasting hydrology regimes. In addition to DOM and nutrients (nitrate, nitrite, phosphate), a series of parameters (δ18O, δD, cation, and DIC) were analyzed to constrain water sources. Five DOM fluorescence components were identified, including two terrestrial humic-like components (C1 and C2), two protein-like components (C3 and C4), and one component (C5) indicative of resistant compounds persisting in deep groundwater. During the period of high discharge, high fluxes of DOM and nutrients were observed, and DOM was characterized by higher %C1, %C2 and %C5, lower %C3 and %C4, greater values of humification index, and lower values of fluorescence index (FI). This observation suggests that high riverine flow mobilized soil-derived OM and resistant OM into the river but suppressed the contributions of autochthonous, microbial OM. δ13C-DOC values fell in a general range indicative of the dominance of C3 plants but became more enriched in agricultural areas, indicating the influence of corn OM. A positive correlation between nutrient concentrations versus FI values during the period of low discharge suggests that irrigation return flow was an important source for both nutrients and humic DOM in the river. Our data demonstrate that watershed exports of nutrients and DOM were collectively controlled by hydrology and watershed land use, and the influence of land use was more evident during low discharge regimes.

  4. [Stem sap flow of grape under different drip irrigation patterns and its relationships with environmental factors in arid oasis region of Shiyang River basin].

    PubMed

    Du, Tai-Sheng; Kang, Shao-Zhong; Zhang, Bao-Zhong; Li, Si-En; Yang, Xiu-Ying

    2008-02-01

    This paper studied the stem sap flow of grape in arid oasis region of Shiyang River basin under conventional drip irrigation (CDI), alternate drip irrigation (ADI), and fixed drip irrigation (FDI), and its relationships with meteorological conditions and soil moisture content. The results showed that the stem sap flow of grape had an obvious day-night rhythm synchronous with solar radiation, and was significantly higher under CDI than under ADI and FDI during new branch growth and flowering stages. Solar radiation and air temperature were the main meteorological factors affecting the hourly sap flow, and the daily stem sap flow had linear relationships with daily air temperature and wind speed. The correlation coefficients between the stem sap flow and the meteorological factors ranked in the order of CDI > ADI > FDI. There was a significant correlation between daily stem sap flow and reference crop evapotranspiration (ET0). Compared with CDI, ADI could save 50% of irrigation water while the stem sap flow only reduced by 6.56%, and an obvious compensation effect between stem sap flow and hydraulic conductivity was observed. PMID:18464634

  5. Identification of spatiotemporal patterns of biophysical droughts in semi-arid region - a case study of the Karkheh river basin in Iran

    NASA Astrophysics Data System (ADS)

    Kamali, B.; Abbaspour, K. C.; Lehmann, A.; Wehrli, B.; Yang, H.

    2015-06-01

    This study aims at identifying historical patterns of meteorological, hydrological, and agricultural (inclusively biophysical) droughts in the Karkheh River Basin (KRB), one of the nine benchmark watersheds of the CGIAR Challenge Program on Water and Food. Standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture deficit index (SMDI) were used to represent the above three types of droughts, respectively. The three drought indices were compared across temporal and spatial dimensions. Variables required for calculating the indices were obtained from the Soil and Water Assessment Tool (SWAT) constructed for the region. The model was calibrated based on monthly runoff and yearly wheat yield using the Sequential Uncertainty Fitting (SUFI-2) algorithm. Five meteorological drought events were identified in the studied period (1980-2004), of which four corresponded with the hydrological droughts with 1-3 month lag. The meteorological droughts corresponded well with the agricultural droughts during dry months (May-August), while the latter lasted for a longer period of time. Analysis of drought patterns showed that southern parts of the catchment were more prone to agricultural drought, while less influenced by hydrological drought. Our analyses highlighted the necessity for monitoring all three aspects of drought for a more effective watershed management. The analysis on different types of droughts in this study provides a framework for assessing their possible impacts under future climate change in semi-arid areas.

  6. Phosphorous concentration, solubility and species in the groundwater in a semi-arid basin, southern Malayer, western Iran

    NASA Astrophysics Data System (ADS)

    Jalali, Mohsen

    2009-05-01

    In areas of intensive crop production, continual phosphorous (P) applications as P fertilizer and farmyard manure have been made at levels exceeding crop requirement. As a result, surface soil accumulations of P have occurred to such an extent that loss of P in surface runoff and a high risk for P transfer into groundwater in concentrations exceeding the groundwater quality standard has become a priority management concern. Phosphorous content of groundwater was determined in order to examine dissolved P concentration and species in the groundwater and mineral solubilitiy in a semi-arid region of southern Malayer, western Iran. The speciation for P in groundwater was calculated using geochemical speciation model PHREEQC. The concentration of total P in the groundwater (0.01-2.56 mg P l-1) and estimated concentrations of HPO4 2- (49.5-89%), H2PO4 - (1.5-17.3%), CaHPO4 + (5.7-36.1%), and CaPO4 - (1.4-12.2%) varied considerably amongst the groundwater. Results suggest that the concentration of P in the groundwater could be primarily controlled by the solubility of octacalcium phosphate and ?-tricalcium phosphate. Large amounts of P fertilizer, inadequate management of P fertilization, and low irrigation efficiency, coupled with sandy soils in some parts of the study area could be mainly responsible for the greater P in the groundwater. In general, the greater the dissolved P concentration in the groundwater, the closer the solution was to equilibrium with respect to the more soluble Ca-phosphate minerals. The groundwater P content could be potentially used to identify areas where management approaches, such as P applied and crop type planted, could be adjusted to different types of soils, geology and topography.

  7. Isotopes in the Hueco Bolson aquifer, Texas (USA) and Chihuahua (Mexico): local and general implications for recharge sources in alluvial basins

    NASA Astrophysics Data System (ADS)

    Eastoe, Christopher J.; Hibbs, Barry J.; Olivas, Alfredo Granados; Hogan, James F.; Hawley, John; Hutchison, William R.

    2008-06-01

    Stable isotope data for the Hueco Bolson aquifer (Texas, USA and Chihuahua, Mexico) distinguish four water types. Two types relate to recharge from the Rio Grande: pre-dam (pre-1916) river water with oxygen-18 and deuterium (?18O, ?D, ‰) from (-11.9, -90) to (-10.1, -82), contrasts with present-day river water (-8.5, -74) to (-5.3, -56). Pre-dam water is found beneath the Rio Grande floodplain and Ciudad Juárez, and is mixed with post-dam river water beneath the floodplain. Two other types relate to recharge of local precipitation; evidence of temporal change of precipitation isotopes is present in both types. Recharge from the Franklin and Organ Mountains plots between (-10.9, -76) and (-8.5, -60) on the global meteoric water line (GMWL), and is found along the western side of the Hueco Bolson, north of the Rio Grande. Recharge from the Diablo Plateau plots on an evaporation trend originating on the GMWL near (-8.5, -58). This water is found in the southeastern Hueco Bolson, north of the river; evaporation may be related to slow recharge through fine-grained sediment. Pre-dam water, recognizable by isotope composition, provides information on groundwater residence times in this and other dammed river basins.

  8. Temporal variations of atmospheric water vapor δD and δ18O above an arid artificial oasis cropland in the Heihe River Basin

    NASA Astrophysics Data System (ADS)

    Wen, Xue-Fa

    2015-04-01

    The high temporal resolution measurements of δD, δ18O, and deuterium excess (d) of atmospheric water vapor provide an improved understanding of atmospheric and ecohydrological processes at ecosystem to global scales. Isotope ratio infrared spectroscopy has recently allowed high-frequency in situ measurements of atmospheric water vapor isotopic ratios in China (Wen et al., 2008, Journal of Hydrology; Wen et al., 2012, Journal of Atmospheric and Oceanic Technology). For our group, in situ and continuous observations of δD, δ18O, and d of atmospheric water vapor have been performed at the surface air in Beijing (Wen et al., 2010, Journal of Geophysical Research-Atmospheres; Zhange et al., 2011, Journal of Geographical Sciences), a winter wheat and summer maize cropland in Luancheng (Wen et al., 2012, Oecologia; Xiao et al., 2012, Global Change Biology), a grassland in Duolun (Hu et al., 2014, Journal of Geophysical Research- Biogeosciences), a spring maize cropland (Huang and Wen, 2014, Journal of Geophysical Research-Atmospheres) and a subtropical coniferous plantation (Yang et al., 2015, Agricultural and Forest Meteorology). In this study (Huang and Wen, 2014), δD, δ18O, and d of water vapor and their flux ratios were continuously measured from May to September 2012 using an in situ technique above an arid artificial oasis in the Heihe River Basin, which has a typical continental arid climate. The monthly δD and δ18O increased slowly and then decreased, whereas the monthly d showed a steady decrease. δD, δ18O, and d exhibited a marked diurnal cycle, indicating the influence of the entrainment, local evapotranspiration (ET), and dewfall. The departures of δD, δ18O, and d from equilibrium prediction were significantly correlated with rain amount, relative humidity (RH), and air temperature (T). The "amount effect" was observed during one precipitation event. δD and δ18O were log linear dependent on water vapor mixing ratio with respective R2 of 17% and 14%, whereas d was significantly correlated with local RH and T, suggesting the less influence of air mass advection and more important contribution of the local source of moisture to atmospheric water vapor. Throughout the experiment, the local ET acted to increase δD and δ18O, with isofluxes of 102.5 and 23.50mmolm-2 s-1‰, respectively. However, the dominated effect of entrainment still decreased δD and δ18O by 10.1 and 2.24‰, respectively. Both of the local ET and entrainment exerted a positive forcing on the diurnal variability in d.

  9. Configuration of water resources for a typical river basin in an arid region of China based on the ecological water requirements (EWRs) of desert riparian vegetation

    NASA Astrophysics Data System (ADS)

    Ling, Hongbo; Guo, Bin; Xu, Hailiang; Fu, Jinyi

    2014-11-01

    Desert riparian vegetation is a natural cover promoting the stability and development of inland river ecosystems in arid regions. Calculating the ecological water requirements (EWRs) of desert riparian vegetation is an important step in achieving reasonable water utilization. Therefore, this study examined the Tarim River, located in an extremely arid region of China, and collected relevant data on hydrology, weather and vegetation using remote sensing. Subsequently, we analyzed the spatial distribution of the desert riparian vegetation in four sections of the Tarim River and calculated the EWR of the desert riparian vegetation using the phreatic evaporation model; additionally, we determined the required runoffs at five hydrologic stations based on the water balance principle. Ultimately, the necessary protection ranges and goals for desert riparian vegetation were established according to the water resource variations in the Tarim River. Our research showed that the total area of desert riparian vegetation along the Tarim River is 16,285.3 km2; this distribution area gradually decreased as the distance from the river increased, and areas varied in the different river sections. The EWRs of desert riparian vegetation from Sections 1 to 5 are 5.698 × 108, 7.585 × 108, 4.900 × 108, 4.101 × 108 m3 and 1.078 × 108 m3, respectively. Therefore, the total EWR of the study region is 23.362 × 108 m3. In terms of the transpiration law of the "unimodal type", the peak value of EWR of natural vegetation occurs in July, and the decreasing trend appears in the other months. Based on the water balance principle, the required runoffs in Alar, Xinquman, Yingbaza, Wusiman and Qiala were determined to be 47.105 × 108, 35.174 × 108, 22.734 × 108, 15.775 × 108 and 7.707 × 108 m3, respectively. According to the water resource frequency and the EWR of the desert riparian vegetation along the Tarim River, we divided the region into three protection ranges: key protection (8.9-11.8 km from the river), basic protection (15.8-21.8 km from the river) and influence protection (43.0 km from the river). This research not only provides a reasonable calculation method for EWR on the scale of a river basin but also supports the healthy development of the desert riparian vegetation ecosystem and helps to achieve the optimal water allocation for this river.

  10. Effects of permafrost degradation on alpine grassland in a semi-arid basin on the Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yi, Shuhua; Zhou, Zhaoye; Ren, Shilong; Xu, Ming; Qin, Yu; Chen, Shengyun; Ye, Baisheng

    2011-10-01

    Permafrost on the Qinghai-Tibetan Plateau (QTP) has degraded over the last few decades. Its ecological effects have attracted great concern. Previous studies focused mostly at plot scale, and hypothesized that degradation of permafrost would cause lowering of the water table and drying of shallow soil and then degradation of alpine grassland. However, none has been done to test the hypothesis at basin scale. In this study, for the first time, we investigated the relationships between land surface temperature (LST) and fractional vegetation cover (FVC) in different types of permafrost zone to infer the limiting condition (water or energy) of grassland growth on the source region of Shule River Basin, which is located in the north-eastern edge of the QTP. LST was obtained from MODIS Aqua products at 1 km resolution, while FVC was upscaled from quadrat (50 cm) to the same resolution as LST, using 30 m resolution NDVI data of the Chinese HJ satellite. FVC at quadrat scale was estimated by analyzing pictures taken with a multi-spectral camera. Results showed that (1) retrieval of FVC at quadrat scale using a multi-spectral camera was both more accurate and more efficient than conventional methods and (2) the limiting factor of vegetation growth transitioned from energy in the extreme stable permafrost zone to water in the seasonal frost zone. Our study suggested that alpine grassland would respond differently to permafrost degradation in different types of permafrost zone. Future studies should consider overall effects of permafrost degradation, and avoid the shortcomings of existing studies, which focus too much on the adverse effects.

  11. Combining SAR with LANDSAT for Change Detection of Riparian Buffer Zone in a Semi-arid River Basin

    NASA Astrophysics Data System (ADS)

    Chang, N.

    2006-12-01

    A combination of RADARSAT-1 and Landsat 5 TM satellite images linking the soil moisture variation with Normalized Difference Vegetation Index (NDVI) measurements were used to accomplish remotely sensed change detection of riparian buffer zone in the Choke Canyon Reservoir Watershed (CCRW), South Texas. The CCRW was selected as the study area contributing to the reservoir, which is mostly agricultural and range land in a semi-arid coastal environment. This makes the study significant due to the interception capability of non-point source impact within the riparian buffer zone and the maintenance of ecosystem integrity region wide. First of all, an estimation of soil moisture using RADARSAT-1 Synthetic Aperture Radar (SAR) satellite imagery was conducted. With its all-weather capability, the RADARSAT-1 is a promising tool for measuring the surface soil moisture over seasons. The time constraint is almost negligible since the RADARSAT-1 is able to capture surface soil moisture over a large area in a matter of seconds, if the area is within its swath. RADARSAT-1 images presented at here were captured in two acquisitions, including April and September 2004. With the aid of five corner reflectors deployed by Alaska Satellite Facility (ASF), essential radiometric and geometric calibrations were performed to improve the accuracy of the SAR imagery. The horizontal errors were reduced from initially 560 meter down to less than 5 meter at the best try. Then two Landsat 5 TM satellite images were summarized based on its NDVI. The combination of and NDVI and SAR data obviously show that soil moisture and vegetation biomass wholly varies in space and time in the CCRW leading to identify the riparian buffer zone evolution over seasons. It is found that the seasonal soil moisture variation is highly tied with the NDVI values and the change detection of buffer zone is technically feasible. It will contribute to develop more effective management strategies for non-point source pollution control, bird habitat monitoring, and grazing and live stock handlings in the future. Future research focuses on comparison of soil moisture variability within RADARSAT-1 footprints and NDVI variations against interferometric SAR for studying riparian ecosystem functioning on a seasonal basis.

  12. A debris flow deposit in alluvial, coal-bearing facies, Bighorn Basin, Wyoming, USA: Evidence for catastrophic termination of a mire

    USGS Publications Warehouse

    Roberts, S.B.; Stanton, R.W.; Flores, R.M.

    1994-01-01

    Coal and clastic facies investigations of a Paleocene coal-bearing succession in the Grass Creek coal mine, southwestern Bighorn Basin, Wyoming, USA, suggest that disruption of peat accumulation in recurrent mires was caused by the repetitive progradation of crevasse splays and, ultimately, by a catastrophic mass movement. The mass movement, represented by deposits of debris flow, marked the termination of significant peat accumulation in the Grass Creek coal mine area. Megascopic and microscopic analyses of coal beds exposed along the mine highwalls suggest that these deposits developed in low-lying mires, as evidenced primarily by their ash yields and maceral composition. Disruption of peat accumulation in successive mires was caused by incursions of sediment into the mire environments. Termination by crevasse splay progradation is represented by coarsening-upward successions of mudrock and tabular, rooted sandstone, which overlie coal beds in the lower part of the coal-bearing interval. A more rapid process of mire termination by mass movement is exemplified by a debris flow deposit of diamictite, which overlies the uppermost coal bed at the top of the coal-bearing interval. The diamictite consists of a poorly sorted, unstratified mixture of quartzite cobbles and pebbles embedded in a claystone-rich or sandy mudstone matrix. Deposition of the diamictite may have taken place over a matter of weeks, days, or perhaps even hours, by catastrophic flood, thus reflecting an instantaneous process of mire termination. Coarse clastics and mud were transported from the southwest some 20-40 km as a viscous debris flow along stream courses from the ancestral Washakie Range to the Grass Creek area, where the flow overrode a low-lying mire and effectively terminated peat accumulation. ?? 1994.

  13. Evaluation of the importance of clay confining units on groundwater flow in alluvial basins using solute and isotope tracers: the case of Middle San Pedro Basin in southeastern Arizona (USA)

    NASA Astrophysics Data System (ADS)

    Hopkins, Candice B.; McIntosh, Jennifer C.; Eastoe, Chris; Dickinson, Jesse E.; Meixner, Thomas

    2014-06-01

    As groundwater becomes an increasingly important water resource worldwide, it is essential to understand how local geology affects groundwater quality, flowpaths and residence times. This study utilized multiple tracers to improve conceptual and numerical models of groundwater flow in the Middle San Pedro Basin in southeastern Arizona (USA) by determining recharge areas, compartmentalization of water sources, flowpaths and residence times. Ninety-five groundwater and surface-water samples were analyzed for major ion chemistry (water type and Ca/Sr ratios) and stable (18O, 2H, 13C) and radiogenic (3H, 14C) isotopes, and resulting data were used in conjunction with hydrogeologic information (e.g. hydraulic head and hydrostratigraphy). Results show that recent recharge (<60 years) has occurred within mountain systems along the basin margins and in shallow floodplain aquifers adjacent to the San Pedro River. Groundwater in the lower basin fill aquifer (semi confined) was recharged at high elevation in the fractured bedrock and has been extensively modified by water-rock reactions (increasing F and Sr, decreasing 14C) over long timescales (up to 35,000 years BP). Distinct solute and isotope geochemistries between the lower and upper basin fill aquifers show the importance of a clay confining unit on groundwater flow in the basin, which minimizes vertical groundwater movement.

  14. Inland Aridification of NW China Since the Late Middle Eocene: Stable Isotope Evidence from Western Qaidam Basin

    NASA Astrophysics Data System (ADS)

    Li, L.; Garzione, C. N.; Pullen, A. T.; Chang, H.; Molnar, P. H.

    2014-12-01

    Cenozoic paleoclimate reconstructions of China, based on pollens, fossils and sedimentary deposits, show a change from planetary aridity to inland aridity of NW China by the early Miocene. However, the initiation of this paleoclimate transition is not well-documented and might be much earlier. The surface uplift of the Tibetan Plateau, the retreat of the Para-Tethys sea, and global cooling have all been suggested to influence the establishment of this inland aridity, although their relative significance remains obscure. This paper presents a stable isotope study of a 4435 m long sedimentary section from the western Qaidam Basin, northern Tibetan Plateau, that spans from the late middle Eocene to late Miocene. The lowermost and uppermost parts of the section are dominated by fluvial and alluvial fan deposits, while the majority of the middle of the section represents palustrine, lower fan delta and marginal to shallow lacustrine fine-grained sediments intercalated with coarse sandstone and conglomerate. Our isotope data show sporadic aridity events in the late middle Eocene to early Oligocene, which might mark the transition from planetary aridity to, or the initiation of, inland aridity in NW China, due to the retreat of the Para-Tethys sea, a process that might be significantly influenced by the early topographic growth of the south-central Tibetan Plateau. A negative shift in oxygen isotope values around 19 Ma is also in accordance with other geological evidence suggesting the Oligocene-early Miocene growth of the Kunlun mountains south of the Qaidam basin. Later intensification of aridity occurred at ~12 Ma that corresponds with a regional climate change event, which we attribute to the upward and outward growth of the northern Tibetan Plateau. The final establishment of extreme inland aridity that is comparable to present day was most likely established at ~3.1-2.6 Ma in the Qaidam basin, and therefore global cooling and northern hemisphere glaciation is a major candidate for the cause.

  15. Impact of wind erosion on detecting active tectonics from geomorphic indexes in extremely arid areas: a case study from the Hero Range, Qaidam Basin, NW China

    NASA Astrophysics Data System (ADS)

    Wu, Lei; Xiao, Ancheng; Yang, Shufeng

    2014-11-01

    Geomorphologic analysis has been used widely to detect active tectonics in regions where fluvial incision is the major erosional process. In this paper, however, we assess the feasibility of utilizing these frequently-used geomorphic indexes (e.g., hypsometric curves, longitudinal channel profiles, normalized stream length-gradient (SLK) index) to determine active tectonics in extremely arid areas where wind erosion also plays an important role. The case study is developed on the Hero Range in the western Qaidam Basin, one of the driest regions on Earth with severe wind erosion since late Pliocene. The result shows that in the west and south sectors, as well as the western part of the east sector, of the Hero Range where fluvial incision prevails, these geomorphic indexes are good indicators of active faulting and consistent with the geological result based on study of fault traces, scarps, faulted Holocene fans and historical seismicity within the past four decades. In contrast, along the northeastern margin (the NE and the SE parts of the east sector) of the range where wind erosion is also important, the results from the geomorphic indexes show quite active tectonics, contrary with the geological evidence favoring weakly active tectonics. Moreover, the positive SLK anomaly lies oblique to the fault trace and the anticline axis but parallel to the wind direction. To reconcile the contradiction, we propose that wind erosion caused by northwestern winds has a tendency to make geomorphic indexes exhibit anomalous values that indicate higher activities, by way of (1) lowering the base-level to generate knickpoints on the longitudinal channel profiles and therefore positive SLK anomalies, and (2) lateral erosion of the mountain front making the hypsometric curves and even the longitudinal channel profiles more convex, and producing obvious slope breaks.

  16. Evolution and palaeoenvironment of the Bauru Basin (Upper Cretaceous, Brazil)

    NASA Astrophysics Data System (ADS)

    Fernandes, Luiz Alberto; Magalhães Ribeiro, Claudia Maria

    2015-08-01

    The Bauru Basin was one of the great Cretaceous desert basins of the world, evolved in arid zone called Southern Hot Arid Belt. Its paleobiological record consists mainly of dinosaurs, crocodiles and turtles. The Bauru Basin is an extensive region of the South American continent that includes parts of the southeast and south of Brazil, covering an area of 370,000 km2. It is an interior continental basin that developed as a result of subsidence of the central-southern part of the South-American Platform during the Late Cretaceous (Coniacian-Maastrichtian). This sag basin is filled by a sandy siliciclastic sequence with a preserved maximum thickness of 480 m, deposited in semiarid to desert conditions. Its basement consists of volcanic rocks (mainly basalts) of the Lower Cretaceous (Hauterivian) Serra Geral basalt flows, of the Paraná-Etendeka Continental Flood Basalt Province. The sag basin was filled by an essentially siliciclastic psammitic sequence. In lithostratigraphic terms the sequence consists of the Caiuá and Bauru groups. The northern and northeastern edges of the basin provide a record of more proximal original deposits, such as associations of conglomeratic sand facies from alluvial fans, lakes, and intertwined distributary river systems. The progressive basin filling led to the burial of the basaltic substrate by extensive blanket sand sheets, associated with deposits of small dunes and small shallow lakes that retained mud (such as loess). Also in this intermediate context between the edges (more humid) and the interior (dry), wide sand sheet areas crossed by unconfined desert rivers (wadis) occurred. In the central axis of the elliptical basin a regional drainage system formed, flowing from northeast to southwest between the edges of the basin and the hot and dry inner periphery of the Caiuá desert (southwest). Life in the Bauru Basin flourished most in the areas with the greatest water availability, in which dinosaurs, crocodiles, turtles, fish, amphibians, molluscs, crustaceans, and charophyte algae lived. The fossil record mainly consists of transported bones and other skeletal fragments. In the northeastern and eastern marginal regions fossils are found in marginal alluvial fan deposits, broad plains of braided streams and ephemeral alkaline water lakes. In the basin interior the fossil record is related to deposits in sand sheets with braided streams, small dunes, and shallow lakes. In the great Caiuá inner desert a few smaller animals could survive (small reptiles and early mammals), sometimes leaving their footprints in dune foreset deposits. The aim of this article is to present and link the basin sedimentary evolution, palaeoecological features and palaeontological record.

  17. Point sources of emerging contaminants along the Colorado River Basin: Source water for the arid Southwestern United States

    USGS Publications Warehouse

    Jones-Lepp, Tammy L.; Sanchez, Charles; Alvarez, David A.; Wilson, Doyle C.; Taniguchi-Fu, Randi-Laurant

    2012-01-01

    Emergingcontaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the UnitedStates. The objective of this study was to evaluate pointsources of ECs along the ColoradoRiver, from the headwaters in Colorado to the Gulf of California. At selected locations in the ColoradoRiver Basin (sites in Colorado, Utah, Nevada, Arizona, and California), waste stream tributaries and receiving surface waters were sampled using either grab sampling or polar organic chemical integrative samplers (POCIS). The grab samples were extracted using solid-phase cartridge extraction (SPE), and the POCIS sorbents were transferred into empty SPEs and eluted with methanol. All extracts were prepared for, and analyzed by, liquid chromatography-electrospray-ion trap mass spectrometry (LC-ESI-ITMS). Log Dow values were calculated for all ECs in the study and compared to the empirical data collected. POCIS extracts were screened for the presence of estrogenic chemicals using the yeast estrogen screen (YES) assay. Extracts from the 2008 POCIS deployment in the Las Vegas Wash showed the second highest estrogenicity response. In the grab samples, azithromycin (an antibiotic) was detected in all but one urban waste stream, with concentrations ranging from 30 ng/L to 2800 ng/L. Concentration levels of azithromycin, methamphetamine and pseudoephedrine showed temporal variation from the Tucson WWTP. Those ECs that were detected in the main surface water channels (those that are diverted for urban use and irrigation along the ColoradoRiver) were in the region of the limit-of-detection (e.g., 10 ng/L), but most were below detection limits.

  18. Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A.

    NASA Astrophysics Data System (ADS)

    Elliott, William S.; Suttner, Lee J.; Pratt, Lisa M.

    2007-12-01

    Continental sediments of the Cloverly and Lakota Formations (Lower Cretaceous) in Wyoming are subdivided into three depositional systems: perennial to intermittent alluvial, intermittent to ephemeral alluvial, and playa. Chert-bearing sandstones, conglomerates, carbonaceous mudrocks, blocky mudrocks, and skeletal limestones were deposited by perennial to intermittent alluvial systems. Carbonaceous mudrocks contain abundant wood fragments, cuticle and cortical debris, and other vascular plant remains representing deposition in oxbow lakes, abandoned channels, and on floodplains under humid to seasonal conditions. Intraformational conglomerates, sandstones, bioturbated and blocky mudrocks with caliche nodules, and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems. Bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo-slickensides. The presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi-arid conditions. Caliche nodules, pseudo-slickensides, and carbonate-rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi-arid climatic conditions. Laminated mudrocks, siltstones, vuggy carbonates, bedded to nodular evaporites, pebbly mudrocks, and diamictites were deposited in evaporative alkaline lakes or playas. Pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa, resulting from intense rain events within the basin. The areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the Early Cretaceous Cordilleran foreland basin in Wyoming. The lower part (A-interval) of the Cloverly and Lakota Formations is characterized by deposits of perennial to intermittent rivers that existed 300 to 1000 km east of the Sevier fold-and-thrust belt. Proximal to the Sevier fold-and-thrust belt, the A-interval of the Cloverly Formation and upper Ephraim Formation of the Gannett Group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains. In the middle part (B-interval) of the Cloverly Formation, intermittent to ephemeral alluvial systems expand to 600 km into the basin. The upper part (C-interval) of the Cloverly Formation is characterized by playa deposits in the Bighorn and Wind River Basins and intermittent to ephemeral alluvial deposits along the front of the ancestral Sevier Mountains. Deposits of perennial to intermittent alluvial systems in the C-interval of the Cloverly and Lakota Formations are restricted to the Black Hills region, almost 900 km to the east of the Sevier Mountains. The change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the Sevier Mountains in the Early Cretaceous.

  19. Mid-Eocene alluvial-lacustrine succession at Gebel El-Goza El-Hamra (Shabrawet area, NE Eastern Desert, Egypt): Facies analysis, sequence stratigraphy and paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Wanas, H. A.; Sallam, E.; Zobaa, M. K.; Li, X.

    2015-11-01

    This study aims to provide the depositional facies, sequence stratigraphic and paleoclimatic characteristics of the Mid-Eocene (Bartonian) continental succession exposed at Gebel El-Goza El-Hamra (Shabrawet Area, NE Eastern Desert, Egypt). The studied succession consists of siliciclastic rocks followed upward by carbonate rocks. Detailed field observation and petrographic investigation indicate accumulation in floodplain-dominated alluvial and shallow lacustrine systems. The floodplain-dominated alluvial facies (45 m thick) is composed mainly of carbonate nodules-bearing, mottled mudrock with subordinate sandstone and conglomerate beds. The conglomerate and pebbly sandstone bodies interpreted as ephemeral braided channel deposits. The massive, laminated, planner cross-bedded, fine- to medium-grained sandstone bodies interlayered within mudstone reflect sheet flood deposits. The mudrocks associated with paleosols represent distal floodplain deposits. The shallow lacustrine facies (15 m thick) is made up of an alternation of marlstone, micritic limestone, dolostone and mudrock beds with charophytes and small gastropods. Both the alluvial and lacustrine facies show evidence of macro-and micro-pedogenic features. Pollen assemblages, stable δ18O and δ13C isotopes, and paleopedogenic features reflect prevalence of arid to semi-arid climatic conditions during the Bartonian. The sequence stratigraphic framework shows an overall fining-upward depositional sequence, consisting of Low- and High-accommodation Systems Tracts (LAST, HAST), and is bounded by two sequence boundaries (SB-1, SB-2). Conglomerate and pebbly sandstone deposits (braided channel and sheet flood deposits) of the lower part of the alluvial facies reflect a LAST. Mudrock and silty claystone facies (distal floodplain deposits) of the upper part of alluvial facies and its overlying lacustrine facies correspond to a HAST. The LAST, HAST and SB were formed during different accommodation-to-sediment supply (A/S) ratio phases. The variation in A/S ratios was mainly controlled by sea-level change as well as by local tectonic subsidence and uplift of the basin coincident with the reactivation of the Syrian Arc System during the Bartonian.

  20. Pleistocene calcareous aeolian-alluvial deposition in a steep relief karstic coastal belt (island of Hvar, eastern Adriatic, Croatia)

    NASA Astrophysics Data System (ADS)

    Pavelić, Davor; Kovačić, Marijan; Vlahović, Igor; Wacha, Lara

    2011-07-01

    Pleistocene aeolian and alluvial deposits occur on the island of Hvar, belonging to the eastern Adriatic karstic coastal belt along the north-eastern Mediterranean margin. The depositional mechanism of the aeolian, alluvial and talus sediments are interpreted based on facies analysis and mineralogical composition. Aeolian deposits are represented by cross-bedded, cross-laminated, and sub-horizontally laminated fine- to medium-grained calcareous sands. The cross-bedded units form tabular sets stacked into cosets. Sets and cosets are separated by distinct low-angle bounding surfaces which mostly dip towards the east interpreted as the upwind direction. Cross-laminated units form isolated sets within the cross-bedded and sub-horizontally laminated units. Cross-bedded and cross-laminated units represent dunes dominated by grain fall and wind ripple deposition, respectively. Dunes produced by sand flow also occur, but are less common. The cross-bedding is truncated by reactivation surfaces. Transverse dunes and some small dome-shaped dunes were also present. Sub-horizontally laminated sandy units represent aeolian sand sheets developed by wind ripple migration in the interdune area. A few wind-rippled dune apron deposits also occur. Trace fossils are locally very abundant within the aeolian deposits, mostly produced by plants. Soft-sediment deformation, such as contorted cross-bedding and pocket structures occur scattered, and rare reddish horizons show pedogenesis. Unlikely most Quaternary coastal aeolian sands, these sands do not include marine bioclasts in composition. The sands are composed of extraclasts dominated by limestone with subordinate chert, quartz-sericite schist, quartzite and quartz. Amphiboles, pyroxene and epidote are the most abundant translucent heavy minerals. The mineralogical composition and palaeoflow directions indicate that the Dinarides were the main provenance of the sand transported by primary easterly and northerly continental winds causing migration of dunes towards the palaeo-Adriatic Sea. Alluvial deposits are intercalated with the aeolian sands. They are composed of breccia derived from a nearby steep hill-ridge, and by resedimented aeolian sand deposited by traction currents during flash floods. Talus fragments reached the aeolian sands only sporadically. Climate strongly affected aeolian, alluvial and talus depositions. During arid conditions dunes migrated forming a dune field, whilst more humid climate triggered heavy rains and generated erosion of aeolian deposits, alluvial sedimentation, colonisation of plants and pedogenesis. Deposition was in a topographic basin, and was controlled by capacity of source area and wind. However, local orography characterised by developed and steep karstic relief strongly affected wind directions, and in that way had specific controls on the dune field evolution. Dominating winds caused seaward dune migration differing from most Mediterranean Quaternary coastal aeolian dune localities characterised by landward migration.

  1. Application of a stochastic weather generator to assess climate change impacts in a semi-arid climate: The Upper Indus Basin

    NASA Astrophysics Data System (ADS)

    Forsythe, N.; Fowler, H. J.; Blenkinsop, S.; Burton, A.; Kilsby, C. G.; Archer, D. R.; Harpham, C.; Hashmi, M. Z.

    2014-09-01

    Assessing local climate change impacts requires downscaling from Global Climate Model simulations. Here, a stochastic rainfall model (RainSim) combined with a rainfall conditioned weather generator (CRU WG) have been successfully applied in a semi-arid mountain climate, for part of the Upper Indus Basin (UIB), for point stations at a daily time-step to explore climate change impacts. Validation of the simulated time-series against observations (1961-1990) demonstrated the models' skill in reproducing climatological means of core variables with monthly RMSE of <2.0 mm for precipitation and ?0.4 °C for mean temperature and daily temperature range. This level of performance is impressive given complexity of climate processes operating in this mountainous context at the boundary between monsoonal and mid-latitude (westerly) weather systems. Of equal importance the model captures well the observed interannual variability as quantified by the first and last decile of 30-year climatic periods. Differences between a control (1961-1990) and future (2071-2100) regional climate model (RCM) time-slice experiment were then used to provide change factors which could be applied within the rainfall and weather models to produce perturbed ‘future' weather time-series. These project year-round increases in precipitation (maximum seasonal mean change:+27%, annual mean change: +18%) with increased intensity in the wettest months (February, March, April) and year-round increases in mean temperature (annual mean +4.8 °C). Climatic constraints on the productivity of natural resource-dependent systems were also assessed using relevant indices from the European Climate Assessment (ECA) and indicate potential future risk to water resources and local agriculture. However, the uniformity of projected temperature increases is in stark contrast to recent seasonally asymmetrical trends in observations, so an alternative scenario of extrapolated trends was also explored. We conclude that interannual variability in climate will continue to have the dominant impact on water resources management whichever trajectory is followed. This demonstrates the need for sophisticated downscaling methods which can evaluate changes in variability and sequencing of events to explore climate change impacts in this region.

  2. Climatic and Tectonic Controls on Alluvial Fan Evolution: The Lost River Range, Idaho

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.; Pierce, J. L.; Sharp, W. D.; Pierce, K. L.

    2006-12-01

    In the northern Basin &Range, alluvial fans developed along the Lost River range-front consist of several distinct inset fan segments with concave-up radial profiles. Multiple large radius (>5 km), shallow (2- 3°), alluvial fans extend across and beyond the active, ~140-km-long, normal Lost River fault. These large fans are relict features, formed by major sheetfloods that occurred intermittently between ~15-180 ka. More recent deposition has been dominated by debris-flows that form small-radius (<2 km), steep (8- 17°), fans closely confined to the mountain front [1,2]. In order to determine the timing of fan surface stabilization, we have undertaken precise mass spectrometric 230Th/U dating of pedogenic carbonate from calcic soils that mantle fan surfaces on the Arco fault segment. Careful selection of mg-size samples of dense soil carbonate pebble coats, from within a trench that cuts through gravelly fan deposits, indicates that the fan soils are geochemically suitable for uranium-series dating (median U=7ppm, 232Th=0.09ppm, 232Th/230Th=154). 230Th/U analysis of these calcic soils can thus provide precise temporal constraints on intervals of surface stability and subsequent soil formation. The oldest fan surface (Qfo1, 178+/-8 ka), exposed within the footwall of the trench, suggests an interval of surface stability, indicating that the fan was likely abandoned due to incision early in MIS 6. Incision may have resulted from surface faulting along the Arco segment of the Lost River fault, but could relate to changes in stream power or sediment supply associated with climatic change or with auto-cyclic variations within the drainage basin. A younger incised and faulted fan surface (Qfo2, 69+/-6 ka), likely represents active alluviation at the beginning of MIS 4 and, since it formed as hanging-wall alluvial gravel, provides age limits on an episode of fault displacement between Qfo1 and Qfo2. In situ pedogenic carbonate coats on sub-angular gravels within the colluvial fault wedge date at 68+/-2 ka, suggesting that either faulting occurred soon after Qfo2 stabilized or that soil carbonate coats were recycled into the colluvial wedge from the faulted surface. Further studies in the Lost River Range will assess the timing of fan deposition, surface stabilization and fault activity since the late Pleistocene using coupled application of Optically Stimulated Thermoluminescence (OSL) dating of loess and fine-sands, and 230Th/U-dating of pedogenic carbonate formed within well- exposed fan stratigraphy. Defining intervals of erosion, deposition and stability within the context of regional records of Quaternary climate change will yield new insights into the interplay between faulting, climate change and alluvial fan deposition and incision in semi-arid environments. [1] Pierce, K.L., Scott, W.E., 1982. Idaho Mines &Geol. Bull. 26. [2] Patterson, S.J., 2006. M.S. Thesis, Montana State University

  3. The origin of groundwater in Zhangye Basin, northwestern China, using isotopic signature

    NASA Astrophysics Data System (ADS)

    Chen, Jiansheng; Liu, Xiaoyan; Sun, Xiaoxu; Su, Zhiguo; Yong, Bin

    2014-03-01

    Zhangye Basin, in arid northwestern China, has recently been repeatedly flooded by rising groundwater. Isotope signatures of sampled waters gained insight into the recharge source of the groundwater. The summer Heihe River water and most of the spring water in Zhangye and Yongchang basins plotted above the global meteoric water line (GMWL) on the ?18O-?D plot. The spring water had R/Ra ratio >1, low TDS and high tritium, which indicates origin from Qilian Mountain glacier meltwater. The groundwater of Qilian Mountains was transported to the Hexi Corridor (in which Zhangye Basin is located) through underground fault zones. Additionally, some of the groundwater in the alluvial plain, and all spring water surrounding Zhangye Basin, plotted below the GMWL on the ?18O-?D plot along an evaporation line, and had R/Ra ratio < 1 and high TDS. It is proposed that the Tibetan rivers or lakes source the Hexi Corridor groundwater through either the NE-trending or NW-trending buried fault zones. The isotopic signatures presented as part of this study rule out the conventional viewpoint that groundwater of the Zhangye Basin was recharged by local precipitation and infiltration of Heihe River water on the alluvial plain.

  4. Dynamics of Transmissionlosses In Arid Stream Channels

    NASA Astrophysics Data System (ADS)

    Lange, J.; Mostert, A.; Wessels, C.

    In dry areas streamflow losses of ephemeral rivers are important contributions to groundwater recharge. The importance of these losses increases with aridity U in hy- perarid areas they often form the only freshwater source for aquifers sustaining water supply and life of the local population. However, just in these areas little is known about processes involved, as gauging and monitoring of surface water flow is made difficult due to the low population, remoteness of hydrological stations and short du- rations of floods. Using a physically based flow routing scheme on an event basis this study wants to contribute to the knowledge of the nature and dynamics of chan- nel transmission losses in large arid stream channels. In the 15500 km2 Kuiseb River catchment, western Namibia, annual rainfall decreases from 275 in the east to just about 0 in the west. With a distinct drop in altitude the downstream part of the basin makes up one of the driest regions in the world. A 200 km channel in the lower reaches of the Kuiseb River serves as an ideal field laboratory to simulate the transmission of flash floods because of the following reasons: i) Almost 20 years of flow records up and downstream ii) Negligible lateral inflow along the reach due to hyperarid condi- tions iii) Comparatively frequent flows due to the semiarid headwaters Hydrographs of two upstream stations serve as input for the routing scheme in a 5 min time step. Geometric information required is taken from aerial photography, topographical maps and surveyed cross sections. At the downstream end of the reach 20 simulated hy- drographs are compared with gauged events. Without calibration the routing scheme nicely documents that small floods (< 60-80 m3/s) are not significantly reduced, if they travel on a wet channel, while under the same circumstances large floods (> 120- 140 m3/s) loose up to 50% of their runoff peak. This difference is important for the assessment of groundwater recharge and may be explained by a flow-dependent scour of silty channel deposits and by the flooding of overbank areas. Hence a realistic trans- mission loss component for flow routing schemes in ephemeral rivers should account for limited alluvial storage and for a runoff-dependent infiltration rate. In the present study two parameters of such a component (i.e. the depth of the active alluvium and a two-stage infiltration rate) are determined by model calibration. In future it is planned to verify these parameters by additional field data and afterwards to apply the routing scheme to the downstream channel reach, the recharge area of an important coastal aquifer.

  5. Seasonality of groundwater recharge in the Basin and Range Province, western North America

    NASA Astrophysics Data System (ADS)

    Neff, Kirstin Lynn

    Alluvial groundwater systems are an important source of water for communities and biodiverse riparian corridors throughout the arid and semi-arid Basin and Range Geological Province of western North America. These aquifers and their attendant desert streams have been depleted to support a growing population, while projected climate change could lead to more extreme episodes of drought and precipitation in the future. The only source of replenishment to these aquifers is recharge. This dissertation builds upon previous work to characterize and quantify recharge in arid and semi-arid basins by characterizing the intra-annual seasonality of recharge across the Basin and Range Province, and considering how climate change might impact recharge seasonality and volume, as well as fragile riparian corridors that depend on these hydrologic processes. First, the seasonality of recharge in a basin in the sparsely-studied southern extent of the Basin and Range Province is determined using stable water isotopes of seasonal precipitation and groundwater, and geochemical signatures of groundwater and surface water. In northwestern Mexico in the southern reaches of the Basin and Range, recharge is dominated by winter precipitation (69% +/- 42%) and occurs primarily in the uplands. Second, isotopically-based estimates of seasonal recharge fractions in basins across the region are compared to identify patterns in recharge seasonality, and used to evaluate a simple water budget-based model for estimating recharge seasonality, the normalized seasonal wetness index (NSWI). Winter precipitation makes up the majority of annual recharge throughout the region, and North American Monsoon (NAM) precipitation has a disproportionately weak impact on recharge. The NSWI does well in estimating recharge seasonality for basins in the northern Basin and Range, but less so in basins that experience NAM precipitation. Third, the seasonal variation in riparian and non-riparian vegetation greenness, represented by the normalized difference vegetation index (NDVI), is characterized in several of the study basins and climatic and hydrologic controls are identified. Temperature was the most significant driver of vegetation greenness, but precipitation and recharge seasonality played a significant role in some basins at some elevations. Major contributions of this work include a better understanding of recharge in a monsoon-dominated basin, the characterization of recharge seasonality at a regional scale, evaluation of an estimation method for recharge seasonality, and an interpretation of the interaction of seasonal hydrologic processes, vegetation dynamics, and climate change.

  6. Implementation of Drainage Water Management in Open Ditch Drainage Systems of the Mississippi Alluvial Valley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased riverine nutrients linked to agricultural activities in the Mississippi River Basin have contributed to degraded surface waters within the basin as well as to the hypoxic zone along the Louisiana Gulf coast. In the Mississippi Alluvial Valley (MAV), these nutrients are transported from agr...

  7. Deep arid system hydrodynamics 2. Application to paleohydrologic reconstruction using vadose zone profiles from the northern Mojave Desert

    USGS Publications Warehouse

    Walvoord, M.A.; Phillips, F.M.; Tyler, S.W.; Hartsough, P.C.

    2002-01-01

    Site-specific numerical modeling of four sites in two arid alluvial basins within the Nevada Test Site employs a conceptual model of deep arid system hydrodynamics that includes vapor transport, the role of xeric vegetation, and long-term surface boundary transients. Surface boundary sequences, spanning 110 kyr, that best reproduce measured chloride concentration and matric potential profiles from four deep (230-460 m) boreholes concur with independent paleohydrologic and paleoecological records from the region. Simulations constrain a pluvial period associated with infiltration of 2-5 mm yr-1 at 14-13 ka and denote a shift linked to the establishment of desert vegetation at 13-9.5 ka. Retrodicted moisture flux histories inferred from modeling results differ significantly from those determined using the conventional chloride mass balance approach that assumes only downward advection. The modeling approach developed here represents a significant advance in the use of deep vadose zone profile data from arid regions to recover detailed paleohydrologic and current hydrologic information.

  8. Risk-assessment of post-wildfire hydrological response in semi-arid basins: The effects of varying rainfall representations in the KINEROS2/AGWA model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Representation of precipitation is one of the most difficult aspects of modeling post-fire runoff and erosion and also one of the most sensitive input parameters to rainfall-runoff models. The impact of post-fire convective rainstorms, especially in semi-arid watersheds, depends on the overlap betwe...

  9. Integration of channel and floodplain suites. I. Developmental sequence and lateral relations of alluvial paleosols.

    USGS Publications Warehouse

    Bown, T.M.; Kraus, M.J.

    1987-01-01

    The lower Eocene Willwood Formation of the Bighorn Basin, northwest Wyoming, consists of about 770 m of alluvial rocks that exhibit extensive mechanical and geochemical modifications resulting from Eocene pedogenesis. Five arbitrary stages are proposed to distinguish these soils of different maturities in the Willwood Formation. An inverse relationship exists between soil maturity and short-term sediment accumulation rate. Illustrates several important principles of soil-sediment interrelationships in aggrading alluvial systems that have broad application to other deposits.-from Authors

  10. Tuffaceous ephemeral lake deposits on an alluvial plain, Middle Tertiary of central California

    USGS Publications Warehouse

    Bartow, J.A.

    1994-01-01

    The Oligocene and Miocene Valley Springs Formation represents a large fluvial depositional system that extended westward from sediment-filled palaeovalleys in the high Sierra Nevada to a piedmont alluvial plain under the present Central Valley. The Valley Springs Formation consists largely of tuffaceous mudrocks, tuffaceous sandstone, polymict conglomerate and rhyodacitic tuff. The tuffaceous mudrock lithofacies probably represents a complex of ephemeral lake and marsh environments on a low gradient alluvial plain. The inferred abundance of shallow lakes, ponds and marshes implies a climate that was wetter than the semi-arid climate of the region today. -from Author

  11. Braided alluvial fan in the Terra Sirenum region, Mars

    NASA Astrophysics Data System (ADS)

    Adeli, S.; Hauber, E.; Le Deit, L.; Kleinhans, M. G.; Platz, T.; Fawdon, P.; Jaumann, R.

    2015-10-01

    Here we report the presence of an Amazonian-aged outflow channel located on the rim of the Ariadnes Colles basin (37°S/178°E) that has an alluvial fan on its downstream part. The study area is located in the Noachian highlands of Terra Sirenum, the site of a large hypothesized paleolake [3]. This so-called Eridania lake existed during the Late Noachian -Early Hesperian and drained into Ma'adim Vallis, one of the largest valleys on Mars. The Ariadnes Colles basin was part of the Eridania paleolake and hosted later a closed lake.

  12. Active Tectonics and Alluvial Rivers

    NASA Astrophysics Data System (ADS)

    Talwani, Pradeep

    Flying into San Francisco, California, for the AGU Fall Meeting from the east coast of the United States, one sees an ever-changing pattern of rivers below. From straight channels, the rivers take on a meandering pattern, become braided, and form oxbow lakes. Their drainage patterns change from regional directions in response to local structures and tectonic activity This carving of the landscape is the response of alluvial rivers to active tectonics manifested locally by ongoing tectonic uplift, river erosion, and alluvial deposition.

  13. Aridity Modulates N Availability in Arid and Semiarid Mediterranean Grasslands

    PubMed Central

    Delgado-Baquerizo, Manuel; Maestre, Fernando T.; Gallardo, Antonio; Quero, José L.; Ochoa, Victoria; García-Gómez, Miguel; Escolar, Cristina; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Noumi, Zouhaier; Derak, Mchich; Wallenstein, Matthew D.

    2013-01-01

    While much is known about the factors that control each component of the terrestrial nitrogen (N) cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC) on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia), including both biotic (e.g. plant cover) and abiotic (e.g. soil OC and pH). If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region. PMID:23565170

  14. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    PubMed

    Delgado-Baquerizo, Manuel; Maestre, Fernando T; Gallardo, Antonio; Quero, José L; Ochoa, Victoria; García-Gómez, Miguel; Escolar, Cristina; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Noumi, Zouhaier; Derak, Mchich; Wallenstein, Matthew D

    2013-01-01

    While much is known about the factors that control each component of the terrestrial nitrogen (N) cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC) on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia), including both biotic (e.g. plant cover) and abiotic (e.g. soil OC and pH). If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region. PMID:23565170

  15. Directional scales of heterogeneity in alluvial fan aquifers

    SciTech Connect

    Neton, M.J.; Dorsch, J.; Young, S.C.; Olson, C.D. . Dept. of Geological Sciences Tennessee Valley Authority Engineering Lab., Norris, TN )

    1992-01-01

    Abrupt lateral and vertical permeability changes of up to 12 orders of magnitude are common in alluvial fan aquifers due to depositional heterogeneity. This abrupt heterogeneity is problematic, particularly in construction of a continuous hydraulic conductivity field from point measurements. Site characterization is improved through use of a scale-and-directionally-related model of fan heterogeneities. A directional classification of alluvial fan aquifer heterogeneities is proposed. The three directional scales of heterogeneity in alluvial fan aquifers are: (1) within-fan, (2) between-fan (strike-parallel), and (3) cross-fan (strike-perpendicular). Within-fan heterogeneity ranges from very small-scale intergrain relationships which control the nature of pores, to larger scale permeability trends between fan apex and toe, and includes abrupt lateral and vertical facies relationships. Between-fan heterogeneities are of a larger-scale and include differences between adjacent (non)coalescent fans along a basin-margin fault due primarily to changes in lithology between adjacent upland source basins. These differences produce different (a) grain and pore fluid compositions, (b) lithologic facies and proportions, and (c) down-fan fining trends, between adjacent fans. Cross-fan heterogeneities extend from source to basin. Fan deposits are in abrupt contact upgradient with low permeability, basin-margin source rock. Downgradient, fan deposits are in gradational to abrupt contact with time-equivalent, generally lower permeability deposits of lake, desert, longitudinal braided and meandering river, volcanic, and shallow marine environments. Throughout basin history these environments may abruptly cover the fan with low permeability horizons.

  16. Sedimentology of Holocene debris flow-dominated alluvial fans, northwest Wyoming: Contributions to alluvial fan facies models

    SciTech Connect

    Cechovic, M.T.; Schmitt, J.G. . Dept. of Earth Sciences)

    1993-04-01

    Facies models for debris flow-dominated alluvial fans are based exclusively upon studies of relatively few fans in the arid American southwest. Detailed geomorphic, stratigraphic, and sedimentologic analyses of several highly-active, debris flow-dominated alluvial fans in northern Yellowstone National Park, WY (temperature, semi-arid) serve to diversify and increase the usefulness of alluvial fan facies models. These fans display an intricate distributary pattern of incised active (0--6 m deep; 700--900 m long) and abandoned channels (1--4 m deep; 400 m long) with levees/levee complexes (<3 m high; <20 m wide; <750 m long) and lobes constructed by pseudoplastic to plastic debris flows. The complex pattern of debris flow deposits is due to repeated channel back filling and overtopping by debris flows behind in-channel obstructions which subsequently lead to channel abandonment. Debris-flow deposition is dominant due to: (1) small, steep (up to 35 degrees) source area catchments, (2) extensive mud rock outcrops in the source area, and (3) episodic summer rainfall events. Proximal to distal fan surfaces exhibit sheetflood deposits several cm thick and up to 70 m in lateral extent. Vertical lithofacies profiles reveal: (1) massive, matrix- and clast-supported gravel units (1--2 m thick) deposited by clast-poor and clast-rich debris flows respectively, with reworked; scoured tops overlain by thin (<0.25 m) trough cross-bedded gravel and ripple cross-laminated sand intervals, and (2) volumetrically less significant 1--2 m thick intervals comprising fining-upward sequences of interbedded cm-scale trough cross-bedded pebbly gravel, massive sand, horizontally stratified sand, and mud rock deposited by hyperconcentrated flow and stream flow during decelerating sheetflood events. Organic rich layers record periods of non-deposition. Channelized stream flow is restricted to minor reworking of in-channel debris flow and hyperconcentrated flow deposits.

  17. Late Miocene to Plio-Pleistocene fluvio-lacustrine system in the Karacasu Basin (SW Anatolia, Turkey): Depositional, paleogeographic and paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Alçiçek, Hülya; Jiménez-Moreno, Gonzalo

    2013-06-01

    The sedimentary record of the late Cenozoic Karacasu Basin, a long-lived continental half-graben from southwestern Turkey, is characterized by siliciclastic and carbonate deposits. Sedimentation was controlled by an active NW-SE trending major normal fault along the basin's southern margin and by climatically-induced lake-level changes. Detailed facies analysis subdivides the entire Neogene-Quaternary basin-fill into three distinct litostratigraphic units representing paleogeographic changes and sedimentation patterns throughout the basin evolution. Sedimentation commenced in the late Miocene with the deposition of proximal-medial alluvial fan and fluvial facies (Damdere Formation; FA1). At this stage, alluvial fans developed in elevated areas to the south, prograding towards the basin center. At the beginning of the Pliocene, fresh to slightly alkaline, shallow lake deposits (FA2a) of the Karacaören Formation formed. The lake became open and meromictic conditions developed (FA2b). Pollen data from the FA2b facies show that climate was arid to humid. Climate probably changed cyclically through time producing alternation of Artemisia steppe (cold and dry periods) and more forested vegetation (warm and wet). The open lake facies passes upwards into lake margin facies (FA2c), but it was still dominated by alkaline to slightly saline lake conditions. Sedimentation was almost continuous from the late Miocene to Pleistocene. In the early Quaternary, the basin was dissected by the re-activation of basin bounding faults. The unconformable base of the overlying Quaternary deposits (Karacasu Formation; FA3) reflected the basin's transformation from a half-graben into a full-graben system. Oxygen isotope data from carbonates show an alternation of humid climatic periods, when freshwater settings predominated, and semiarid/arid periods in which the basin hosted alkaline and saline water lakes. Neotectonic activity has rejuvenated many of the basin-bounding faults, causing development of talus aprons and local alluvial fans. The basin was progressively incised by modern rivers that have largely smoothed out the topographic relief of the graben margins. id="ab0010" The study highlights to the paleo-geography/-climatology in the east Mediterranean.

  18. Taphonomy and paleoecology of nonmarine mollusca: indicators of alluvial plain lacustrine sedimentation, upper part of the Tongue River Member, Fort Union Formation ( Paleocene), Northern Powder River Basin, Wyoming and Montana ( USA).

    USGS Publications Warehouse

    Hanley, J.H.; Flores, R.M.

    1987-01-01

    The composition, species abundances, and spatial and temporal distributions of mollusc assemblages were controlled by the environments in which they lived and the depositional processes that affected the molluscs after death and before final burial. Post-mortem transport, reworking and concentration of shells, and mixing of faunal elements from discrete habitats produced a taphonomic 'overprint' on assemblage characteristics that directly reflects the processes of alluvial plain and floodbasin lacustrine sedimentation. The 'overprint' can be interpreted from outcrop analysis of molluscan biofabric, which consists of: 1) orientation, fragmentation, size-sorting, abrasion, density, and dispersion of shells, 2) the nature and extent of shell-infilling, and 3) ratio of articulated to disarticulated bivalves. Taphonomic characteristics were used with sedimentological properties to differentiate in-place, reworked, transported, and ecologically mixed mollusc assemblages. This study also defines the paleoecology of habitat preferences of mollusc species as a basis for recognition of the environments in which these assemblages were deposited: 1) large floodbasin lakes, 2) small floodbasin lakes, and 3) crevasse deltas and splays. Integration of sedimentology and paleoecology provides an interdisciplinary approach to the interpretation of alluvial environments through time in the Tongue River Member. -Authors

  19. Surface roughness as a calibrated proxy for dating alluvial surfaces

    NASA Astrophysics Data System (ADS)

    Mushkin, A.; Sagy, A.; Trabelci, E.

    2012-12-01

    Determining the age of alluvial deposits, which often constitute effective recorders of tectonic and climatic signals, is a pivotal component in many quantitative studies of recent tectonic activity, past climatic variations and landscape evolution processes. In arid to semi-arid desert environments the scarcity in suitable materials for dating commonly implies that numerical dating of alluvial surfaces remains a challenging and fairly expensive task, carried out on an opportunistic basis and typically requiring substantial commitment of resources. With the goal of addressing this problem, we present a new and widely applicable surface dating technique that builds on surface roughness as a quantitative calibrated proxy for the age of alluvial surfaces in desert environments. The well-studied development of reg soils provides the physical basis for the approach, and recent technological advances in the form of portable ground-based laser scanners (LiDAR), facilitate its application by allowing quantitative high resolution (~several millimeters) 3D characterization of the roughness of alluvial chronosequences as they mature into smooth and stable desert pavements. We construct regional age-roughness calibration curves using 'conventional' numerical dating techniques and LiDAR to quantitatively characterize the evolution trends and time-scales associated with roughness changes of reg soils through time. Here, we present results from two previously dated late Quaternary alluvial chronosequences along the Dead Sea Transform in the hyper-arid Negev desert of southern Israel. LiDAR scanning was applied on representative areas (~30-50 m2) of 10 separate terraces ranging from rough (active surfaces) to fairly smooth surfaces with well-developed pavements displaying an OSL age of 87 kyr. Power spectral density (PSD) analysis was used to characterize the roughness evolution trend of these terraces: We find typical and recurring time-dependent changes in the offset as well as shape of the PSD curves in both chronosequences: PSD offset is continuously reduced over time reflecting the overall reduction in the amplitude of roughness at all wavelengths. All PSD curves display moderation of slopes at the longer wavelengths, which consistently increases with increasing surface age. The kink point itself in the PSD curves is systematically shifted to shorter wavelengths. This characteristic evolution of PSD offset and slope moderation at longer wavelengths reflects the typical break up of boulder-sized clasts through time as such reg soil surfaces mature into well-developed desert pavements. Deviation of the PSD curve from the characteristic evolution pattern also serves as an indication in cases where the natural surface evolution was interrupted. Accordingly, we thus suggest that with suitable regional calibration curves, PSD analysis of desert alluvial surfaces can serve as a practical and quantitative proxy for constraining surface age in places where 'conventional' dating cannot be applied.

  20. Radiogenic 3He/4He Estimates and Their Effect on Calculating Plio-Pleistocene Cosmogenic 3He Ages of Alluvial-Fan Terraces in the Lower Colorado River Basin, USA

    NASA Astrophysics Data System (ADS)

    Fenton, C.; Pelletier, J.

    2005-12-01

    Several alluvial-fan terraces near Topock, AZ were created by successive entrenchment of Pliocene and Pleistocene alluvial-fan gravels shed from the adjacent Black Mountains along the lower Colorado River corridor below Hoover Dam. These fans interfinger with and overlie main-stem Colorado River sands and gravels and grade to terrace levels that correspond with pre-existing elevations of the Colorado River. Absolute dates for the ages of Quaternary deposits on the lower Colorado River are rare and cosmogenic 3He age estimates of these surfaces would help constrain the timing of aggradation and incision in the lower Colorado River corridor. We analyzed individual basalt boulders from several terrace surfaces for total 3He/4He concentrations to calculate cosmogenic 3He ages of each fan terrace; 3He/4He values, expressed as R/Ra where Ra is the 3He/4He of air, range from 0.29 to 590. Black Mountain volcanic rocks have reported K-Ar ages between 15 and 30 Ma and basalt samples from adjacent alluvial fans contain 0.42 to 47× 1012 at/g of 4He, which has likely accumulated due to nuclear processes. The amount of radiogenic 3He/4He can be significant in old rocks with young exposure ages and can complicate determination of cosmogenic 3 He content. Alpha-decay of U, Th, and their daughter isotopes produces large amounts of 4He, whereas significant amounts of radiogenic 3He are only produced through the neutron bombardment of Li and subsequent beta-decay of tritium. We measured Li, U, Th, major and rare-earth element concentrations in whole-rock basalts and mineral separates. These concentrations are used to estimate the ratio of radiogenic helium contributed to the total helium system in our samples. Li concentrations typically range from 6 to 17 ppm, with one outlier of 62 ppm. U contents range from <0.1 to 2.7 ppm and Th contents range from 0.4 to 15.3 ppm. Based on these values, our calculations predict that the average radiogenic helium (R/Ra) contributed to the total helium in Black Mountain basalt samples is 0.011. Other noble gas studies have shown that radiogenic 3He/4He is independent of the U content, nearly independent of the Th content, and strongly influenced by the Li content of a rock; we find the same results. It is assumed that mantle gases are released when the sample is crushed into a fine powder before melting in a furnace under vacuum. To correct for the possible presence of mantle gases in our age-calculations, we crushed two samples under vacuum to measure the R/Ra value (7.9 and 16.03) of mantle helium trapped in fluid inclusions in olivines and pyroxenes. Based on our 3He corrections and calculations, boulders on these alluvial fans range in age from 10 ka to 2.7 Ma.

  1. Geochemical signature and properties of sediment sources and alluvial sediments within the Lago Paranoá catchment, Brasilia DF: a study on anthropogenic introduced chemical elements in an urban river basin.

    PubMed

    Franz, C; Makeschin, F; Weiß, H; Lorz, C

    2013-05-01

    One of the largest urban agglomerations in Brazil is the capital Brasilia and its surrounding area. Due to fast urban sprawl and accelerated land use changes, available water supplies are near their limits. The water supply depends largely on surface water collected in reservoirs. There are increasing concerns regarding water shortages due to sediment aggradations, and of water quality due to geochemical modification of sediments from human activities. The concentration of 18 chemical elements and five sediment properties was analyzed from different potential land-based sediment sources and deposited alluvial sediment within the Lago Paranoà catchment. The goal of this study was to assess the distribution of chemical elements and geochemical/physical properties of potential sediment sources in the Lago Paranoá catchment. Principal component analysis and hierarchical cluster analysis were used to investigate the influence of different land use types on the geochemistry of sediments. Geochemical fingerprints of anthropogenic activities were developed based on the results of the cluster analysis grouping. The anthropogenic input of land use specific geochemical elements was examined and quantified by the calculation of enrichment factors using the local geological background as reference. Through comparison of the geochemical signature of potential sediment sources and alluvial sediments of the Lago Paranoá and sub-catchments, the relative contribution of land use specific sediment sources to the sediment deposition of the main water reservoir were estimated. The existing findings suggest a strong relationship between land use and quantifiable features of sediment geochemistry and indicate that urban land use had the greatest responsibility for recent silting in the Lago Paranoá. This assessment helps to characterize the role of human activities in mixed-used watersheds on sediment properties, and provides essential information to guide management responses towards more effective source-reduction strategies. PMID:23542435

  2. Anthropogenic driven modern recharge and solute flux to arid basin aquifers: Results and implications for sustainability based on field observations and computational modeling

    NASA Astrophysics Data System (ADS)

    Robertson, W. M.; Sharp, J. M.

    2013-12-01

    Development of natural grass and scrubland for agricultural use (grazing and irrigated agriculture) has changed recharge mechanisms and raised questions about the sustainability of groundwater resources in the Trans-Pecos region of Texas. When quantifying the availability of water in the region, previous research relied upon the ';classic' conceptual model; minimal modern recharge, no widespread recharge on basin floors, and no recharge from anthropogenic sources such as irrigation return flow. Increasing nitrate (NO3-) concentrations in basin groundwater from the 1950's to present (median increase of 3-4 mg/L (as NO3-) over approximately 40 years) belie the model of limited modern recharge and pose a risk to water quality throughout the basins. We posit that grazing practices and irrigated agriculture have affected hydrologic processes in the basins by altering 1) the vegetation regime on the basin floors and 2) the magnitude and spatial distribution of infiltrating water. These impacts have increased recharge and transported Cl- and mobile nitrogen (N) from the vadose zone to the underlying groundwater. Using a spatially distributed net infiltration model, we estimate that between 7-20% of recharge occurring in the basins results from widespread recharge on the basin floors and that between 1960 and 2000 an additional 8.5 x 10^3 to 1.2 x 10^6 cubic meters of irrigation water has potentially been returned through irrigation return flow. Vadose zone cores collected from beneath land used for agricultural purposes document changes in water content and pore water chemistry that imply an increase in downward flux of moisture and solute resulting from human alteration of the natural system; reservoirs of NO3- and Cl- typically observed beneath the rooting depth of un-impacted vegetation are either displaced downward or flushed beyond the core depth under land with historical or ongoing irrigated agriculture. There are significant implications for the sustainability of groundwater resources in this system based upon the trends in groundwater NO3- concentrations, vadose zone core data, and results of the net infiltration models: 1) there may be more recharge to the basins than previously estimated and 2) there is a potential long-term concern for water quality. Due to the thick unsaturated zone in much of the system, long travel times are expected between the base of the root zone and the water table. It is unclear if the flux of NO3- and Cl- to the groundwater has peaked or if effects from the alteration of the natural vegetation regime will continue for years to come.

  3. Nitrate in Arid Basin Groundwater: How Historical Trends in Water Quality, Pumping Practices, and Land Use Inform our Understanding of Flow in these Systems

    NASA Astrophysics Data System (ADS)

    Robertson, W. M.; Sharp, J. M., Jr.

    2011-12-01

    During the past 60 years, an overall increase in nitrate (NO3-) concentration has been observed in basinal groundwaters of the Trans-Pecos region of West Texas. In wells where data from multiple decades are available (n = 60), 75% had an increase in NO3- concentration of greater than 1mg/L that appears largely independent of changes in salinity; some wells experienced an increase in NO3- and TDS while others experienced an increase in NO3- with no change or a decrease in TDS. These changes in water quality are rapid in comparison to previously estimated rates of recharge to these basins (~10,000 yrs). We infer that changes in land use and pumping practices over the past 6 decades are partially responsible for the observed changes in water quality and water level in the basin aquifers. In the summer of 2011, we collected water quality information (including NO3 and TDS) from approximately 80 wells in five basins located in the Trans-Pecos Region of West Texas; Red Light Draw, Lobo and Ryan Flats, Eagle Flats, Wild Horse and Michigan Flats, and the Northern Salt Basin. We have combined these data with past water quality data, water level monitoring, pumping records, and historical land use data (including historical aerial photographs and historical land cover data sets) to examine how anthropogenic effects have altered recharge, flow systems, and water quality in these basins over the past 60 years. We observe that the largest historical users of water in the region have water with some of the highest NO3- concentrations and the largest increases in NO3- during the period of examination; this indicates a potential anthropogenic source for (at least some of) the NO3- in the basin aquifers. Water tables have rebounded and salinity has decreased in areas of some basins where irrigated agriculture has been curtailed, though the trends in NO3- concentrations are less clear. These observations point to flow systems that are more preferentially permeable and more complex than is reflected in current groundwater models.

  4. Co-contamination of As and F in alluvial aquifer

    NASA Astrophysics Data System (ADS)

    Kim, S.; Kim, K.; Kim, B.; Zhu, W.; Lee, E.; Ko, K.

    2010-12-01

    Co-contamination of As and F is frequently observed in alluvial aquifers of many countries including Argentina, Mexico, China, and Pakistan. However, processes causing this phenomenon are still poorly understood. In arid or semi-arid areas, the aquifers are generally under oxidizing condition and As and F show a good correlation. In contrast, groundwaters under reducing condition generally show a poorer correlation. In this study, we explored the geochemical mechanisms causing the co-contamination of As and F and their poorer correlation in the reducing environment by investigating alluvial groundwaters of the Mankyeong River floodplain, Korea. For this study, we collected 72 groundwater samples from 42 shallow wells placed into the alluvial aquifer. Desorption experiments using soils collected from the study area were also performed. Groundwater chemistry data showed that waters are under strong reducing condition and the reductive dissolution of Fe oxides was the main process increasing As concentration in groundwaters. The co-contamination was also observed in the study area and F did not show a good correlation with As. F showed concentrations increasing with pH. Desorption experiments also showed the dependences of As and F on pH. The experiments using soils treated with Na citrate-NaHCO3-dithonite solution indicated that iron oxides were the main phases hosting both As and F in soils. In our study area, pH of groundwaters increases due to a series of reduction reactions, and which increased F concentration by desorption from iron oxides. This result suggests that sharing the same adsorption hosts and the pH increased by reduction reactions are the main reason for the co-occurrence of As and F in alluvial groundwater under reducing environments. The lack of correlation between As and F was derived by the precipitation of As as sulfides in sulfate reducing condition. However, the correlation could be much better in the oxidizing condition because As released from iron oxides by pH increase cannot be removed as sulfides.

  5. Assessing groundwater recharge in an Andean closed basin using isotopic characterization and a rainfall-runoff model: Salar del Huasco basin, Chile

    NASA Astrophysics Data System (ADS)

    Uribe, Javier; Muñoz, José F.; Gironás, Jorge; Oyarzún, Ricardo; Aguirre, Evelyn; Aravena, Ramón

    2015-11-01

    Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial plains. Salt flats in the closed basins in arid northern Chile are extremely important ecological niches. The Salar del Huasco, one of these salt flats located in the high plateau (Altiplano), is a Ramsar site located in a national park and is composed of a wetland ecosystem rich in biodiversity. The proper management of the groundwater, which is essential for the wetland function, requires accurate estimates of recharge in the Salar del Huasco basin. This study quantifies the spatio-temporal distribution of the recharge, through combined use of isotopic characterization of the different components of the water cycle and a rainfall-runoff model. The use of both methodologies aids the understanding of hydrological behavior of the basin and enabled estimation of a long-term average recharge of 22 mm/yr (i.e., 15 % of the annual rainfall). Recharge has a high spatial variability, controlled by the geological and hydrometeorological characteristics of the basin, and a high interannual variability, with values ranging from 18 to 26 mm/yr. The isotopic approach allowed not only the definition of the conceptual model used in the hydrological model, but also eliminated the possibility of a hydrogeological connection between the aquifer of the Salar del Huasco basin and the aquifer that feeds the springs of the nearby town of Pica. This potential connection has been an issue of great interest to agriculture and tourism activities in the region.

  6. Trends and climatic sensitivities of vegetation phenology in semiarid and arid ecosystems in the US Great Basin during 1982-2011

    NASA Astrophysics Data System (ADS)

    Tang, G.; Arnone, J. A., III; Verburg, P. S. J.; Jasoni, R. L.; Sun, L.

    2015-12-01

    We quantified the temporal trend and climatic sensitivity of vegetation phenology in dryland ecosystems in the US Great Basin during 1982-2011. Our results indicated that vegetation greenness in the Great Basin increased significantly during the study period, and this positive trend occurred in autumn but not in spring and summer. Spatially, increases in vegetation greenness were more apparent in the northwestern, southeastern, and eastern Great Basin but less apparent in the central and southwestern Great Basin. In addition, the start of growing season (SOS) was not advanced while the end of growing season (EOS) was delayed significantly at a rate of 3.0 days per decade during the study period. The significant delay in EOS and lack of earlier leaf onset caused growing season length (GSL) to increase at a rate of 3.0 days per decade. Interestingly, we found that the interannual variation of mean vegetation greenness calculated for the period of March to November (spring, summer, and autumn - SSA) was not significantly correlated with mean surface air temperature in SSA but was strongly correlated with total precipitation. On a seasonal basis, the variation of mean vegetation greenness in spring, summer, and autumn was mainly attributable to changes in pre-season precipitation in winter and spring. Nevertheless, climate warming appeared to play a strong role in extending GSL that, in turn, resulted in the upward trend in mean vegetation greenness. Overall, our results suggest that changes in wintertime and springtime precipitation played a stronger role than temperature in affecting the interannual variability of vegetation greenness, while climate warming was mainly responsible for the upward trend in vegetation greenness we observed in Great Basin dryland ecosystems during the 30-year period from 1982 to 2011.

  7. Estimating the spatial distribution of snow water equivalent and simulated snowmelt runoff modeling in headwater basins of the semi-arid Southwest

    NASA Astrophysics Data System (ADS)

    Dressler, Kevin A.

    The spatial distribution of snowpack in relation to snow water equivalent (SWE) and covered extent is highly variable in time both seasonally and interannually. In order to assess basin water resources, SWE must be distributed to areal estimates. This spatially distributed SWE connects the point scale to the larger scale of the basin (i.e. macro-scale), requiring a combination approach of statistical interpolation techniques and snowpack extent constraint from remote sensing. This research connects those multiple spatial scales and applies the combined remote sensing and ground-based SWE products in a hydrologic model setting to aid in improving streamflow forecasting in the mountainous terrain of snowmelt-dominated basins, a current modeling gap. Four specific advancements were achieved: (1) a comprehensive assessment of spatial distribution techniques in interpolating point snow water equivalent (SWE) measurements at snow telemetry (SNOTEL) stations to the macro-scale was made and an optimal technique for distributing SWE on this scale was obtained; (2) differences between two major data sources of SWE (SNOTEL and snowcourse) were quantified for both point-scale variability and interpolated macro-scale variability to determine spatial and temporal differences in data sources for dry, average and wet years to better inform water resources management applications; (3) basin-scale estimates of ground-based SWE and snow covered area (SCA) from remote sensing were evaluated relative to equivalent fields calculated by a hydrologic model and the effect of assimilating the remote sensing products into the model were investigated; and (4) in the context of (3), improvements were made in macro-scale SCA estimates through both a canopy correction and a low pass statistical filter in an effort to correct for the relatively low resolution of remotely sensed estimates.

  8. INFLUENCE OF SEDIMENT SUPPLY, LITHOLOGY, AND WOOD DEBRIS ON THE DISTRIBUTION OF BEDROCK AND ALLUVIAL CHANNELS

    EPA Science Inventory

    Field surveys in the Willapa River basin, Washington State, indicate that the drainage area?channel slope threshold describing the distribution of bedrock and alluvial channels is influenced by the underlying lithology and that local variations in sediment supply can overwhelm ba...

  9. Using the Bidirectional Reflectance Distribution Function (BRDF) for remotely mapping surface roughness on alluvial fans: A comparison of Death Valley, CA to Mojave Crater on Mars

    NASA Astrophysics Data System (ADS)

    Doyle, S. L.; Wilkinson, M. J.; Scuderi, L. A.; Weissmann, G. S.; Scuderi, L. J.

    2011-12-01

    The Bidirectional Reflectance Distribution Function (BRDF) describes how incoming light from a given direction is reflected from specific surfaces in response to different incoming solar radiation angles. The amount and directionality of reflected light is a function of surface roughness and orientation. The goal of this study is to assess whether a BRDF based approach may be applicable for creating surface roughness maps for Martian alluvial fans. Landsat 7 satellite imagery is used to make classifications of surfaces with different roughness and spectral properties for alluvial fan surfaces in Death Valley, California. The resulting classes have been interpreted to represent surfaces of different ages and also different deposit types. In Death Valley, older surfaces are classified based on the amount of shadowing due to gully formation, differences in the amount of surface smoothness from desert pavement formation, and desert varnish color variations. In contrast, the most recently formed surfaces have an assemblage of classes that represent surface deposits of different grain size and sorting, as well as different landform types - incised channels and elevated bars. Many Death Valley fans have a telescoping morphology where progressively younger surfaces reach basin-ward. This is more evident on some fans using a BRDF classification. A similar map was made for depositional landforms within Mojave Crater on Mars, identified as sub-kilometer alluvial fans by Williams and Malin (2008). These alluvial fans are the youngest found on Mars (Amazonian age) and have topographic similarities to fans in the southwestern US. Any geomorphic similarities between Death Valley fans and those within Mojave Crater can be assessed using surface roughness. Imagery from both the High Resolution Imaging Experiment (HiRISE) and Context Camera (CTX) onboard the Mars Reconnaissance Orbiter (MRO) were used to compare differences in spatial resolution on BRDF classifications. The resulting surface roughness maps are strikingly similar in classes and patterns to many fans within Death Valley. The surfaces interpreted by Williams and Malin (2008) to be evidence of multiple flow events are clearly classified using BRDF. In addition to age differences, possible locations of materials with different grain size and sorting are also identified. Since the BRDF classes of certain surface features on Earth and Mars fans largely overlap, field observations for each class type made for Death Valley fan surfaces may be useful for understanding the past fluvial processes on Mars and their similarities with fan forming processes in arid regions on Earth. This remote sensing approach has the potential to provide a tool for studying fans that may be inaccessible or too large for extensive fieldwork.

  10. Anabranching Channel Patterns: the Kingdom of Large Alluvial Rivers

    NASA Astrophysics Data System (ADS)

    Latrubesse, E. M.

    2014-12-01

    For a long time anabranching patterns were primarily restricted to "exotic and remote" zones in arid systems such as Australia. For that reason, they were not accepted as a major topic of discussion in our discipline, which was based on concepts principally derived from case studies in the Northern Hemisphere. However, anabranching alluvial patterns are widespread in a variety of environments and scales, from arid small rivers to alluvial reaches of giant rivers such as the Amazon, Congo, and Negro. The largest rivers of the world in water discharge are anabranching, and the majority of the forty-five largest rivers (water discharges >5000m3s-1) are dominantly anabranching systems. Only a small number of rivers with meandering patterns, or sinuous with branches (meandering-tendency to anabranch) are part of the largest rivers group. The present large anabranching rivers with well developed floodplains flowing on lowlands have in common a characteristic very slow slopes, specific stream power of < 25 Wm-2 and sandy bed load with sand sizes dominantly ranging from 0.1 < D50 <0.5 mm. Large axial anabranching rivers also contain the largest floodplains. The diversity of planforms and island morphologies in large anabranching rivers result from autogenic adjustments to millennial scales in broad valleys and to century-decadal scale channel-floodplain processes. The variety of anabranching styles are not specifically related to a single explanatory "physically based theory" but to a variety of morphological processes, complex-channel floodplain interactions and the geologic characteristics of the valleys. Once considered a kind of oddity, anabranching rivers must be considered major and fundamental representatives of the fluvial world.

  11. Anabranching Channel Patterns: the Kingdom of Large Alluvial Rivers

    NASA Astrophysics Data System (ADS)

    Latrubesse, Edgardo

    2015-04-01

    For a long time anabranching patterns were primarily restricted to "exotic and remote" zones in arid systems such as Australia. For that reason, they were not accepted as a major topic of discussion in our discipline, which was based on concepts principally derived from case studies in braided and meandering rivers of the Northern Hemisphere. However, anabranching alluvial patterns are widespread in a variety of environments and scales, from arid small rivers to alluvial reaches of giant rivers such as the Amazon, Congo, and Negro. The largest rivers of the world in water discharge are anabranching, and the majority of the forty-five largest rivers (water discharges >5000m3s-1) are dominantly anabranching systems. Only a small number of rivers with meandering patterns, or sinuous with branches (meandering-tendency to anabranch) are part of the largest rivers group. The present large anabranching rivers flowing on lowlands and well developed floodplains have in common a characteristic very slow slopes, specific stream power of < 25 Wm-2 and sandy bed load with sand sizes dominantly ranging from 0.1 < D50 <0.5 mm. The diversity of planforms and island morphologies in large anabranching rivers result from autogenic adjustments to millennial scales in broad valleys and to century-decadal scale channel-floodplain processes. The variety of anabranching styles are not specifically related to a single explanatory "physically based theory" but to a variety of morphological processes, complex-channel floodplain interactions and the geologic characteristics of the valleys. Once considered a kind of oddity, anabranching rivers must be considered major and fundamental representatives of the fluvial world.

  12. Meander wavelength of alluvial rivers.

    PubMed

    Schumm, S A

    1967-09-29

    Data on river channel and sediment characteristics were collected at 36 cross sections of stable alluvial river channels in Australia and western United States. These data demonstrate that the meander wavelength of a river is dependent not only on water discharge, but also on the type of sediment load moved through the channel. The meander wavelength of rivers that are transporting a high proportion of their total sediment load as both sand and gravel will be greater than the meander wavelengths of channels of similar discharge which are transporting mainly fine sediment loads. PMID:17816939

  13. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    PubMed

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime. PMID:24737419

  14. Key Eco-Hydrological Parameters Retrieval and Land Data Assimilation System Development in a Typical Inland River Basin of China's Arid Region- Final Results

    NASA Astrophysics Data System (ADS)

    Li, Xin; Wang, Shuguo; Han, Xujun

    2013-01-01

    During Dragon 2 period, fruitful results have been achieved with regard to the estimation of land surface parameters and the development of a catchment scale land data assimilation system in the Heihe River Basin (HRB), China. By using multi-platforms (satellite, aircraft, crane-based, ground station etc.), various observation results have been obtained, paving the way for carrying out a variety of dedicated and novel retrieval investigations related to eco-hydrological parameters, e.g. precipitation, snow properties, soil moisture (SM), land surface temperature (LST), evapotranspiration (ET), canopy resistance, leaf chlorophyll content, bi-directional reflectance, albedo. In addition, the Heihe data assimilation system has been developed to make use of these multi-source observations at the catchment scale, in order to improve the estimation of SM, soil temperature, ET, snow and streamflow at 1 km spatial resolution with a temporal resolution of 1 hour.

  15. Report from working group on alluvial pedogenesis

    USGS Publications Warehouse

    Autin, W.J.; Aslan, A.; Bettis, E.A.; Walthall, P.M.

    1998-01-01

    These uses illustrate the complexity of alluvial pedogenesis as it relates to the analysis and interpretation of paleosols. Difficulties with interpretations of alluvial paleosols are probably greatest when applied to the preserved sedimentary record, where direct evidence of paleolandscape variability is scanty or lacking.

  16. Differentiating tectonic from climatic factors in the evolution of alluvial fans

    SciTech Connect

    Wilson, D.S.; West, R.B. . Dept. of Geology)

    1993-04-01

    Alluvial fans are integral parts of landscapes of arid and semi-arid regions and are most commonly found along the flanks of tectonically active mountain ranges. Alluvial fans are sensitive indicators of tectonic and climatic activity through time. Three dimensional fan modelling has the potential to discriminate between these two forces and provide quantitative estimates of deformation of fan surfaces due to tilting, faulting, or folding. The model has tremendous potential for seismic hazard evaluation at both the reconnaissance and detailed level of investigation. The ability to recognize deformation of alluvial fans alleviates the need for postulation of complex interactions between climate and internal variables in the depositional system leading to present fan morphology. The greatest problems associated with fan modelling come from failure to identify individual segments. Inclusion of more than one segment can lead to poor model performance or, more likely, inaccurate results. The long term tectonic influence on a fan's evolution can be assessed from the differences in deformation of different segments. Reliable correlations of segments from different fans along the same mountain front can provide a means to asses regional deformation. Once tectonic effects are taken into account, then climatic effects can be evaluated. Previous fan models have failed to recognize areal limitations, failed to account for deformation, or assumed deformation geometry.

  17. Modeling of groundwater level fluctuations using dendrochronology in alluvial aquifers

    NASA Astrophysics Data System (ADS)

    Gholami, V.; Chau, K. W.; Fadaee, F.; Torkaman, J.; Ghaffari, A.

    2015-10-01

    Groundwater is the most important water resource in semi-arid and arid regions such as Iran. It is necessary to study groundwater level fluctuations to manage disasters (such as droughts) and water resources. Dendrochronology, which uses tree-rings to reconstruct past events such as hydrologic and climatologic events, can be used to evaluate groundwater level fluctuations. In this study, groundwater level fluctuations are simulated using dendrochronology (tree-rings) and an artificial neural network (ANN) for the period from 1912 to 2013. The present study was undertaken using the Quercus Castaneifolia species, which is present in an alluvial aquifer of the Caspian southern coasts, Iran. A multilayer percepetron (MLP) network was adopted for the ANN. Tree-ring diameter and precipitation were the input parameters for the study, and groundwater levels were the outputs. After the training process, the model was validated. The validated network and tree-rings were used to simulate groundwater level fluctuations during the past century. The results showed that an integration of dendrochronology and an ANN renders a high degree of accuracy and efficiency in the simulation of groundwater levels. The simulated groundwater levels by dendrochronology can be used for drought evaluation, drought period prediction and water resources management.

  18. The origin and geologic evolution of the East Continent Rift Basin

    SciTech Connect

    Drahovzal, J.A. . Kentucky Geological Survey)

    1992-01-01

    The East Continent Rift Basin (ECRB) is a newly recognized, dominantly sedimentary-volcanic Proterozoic rift basin that apparently represents the southern extension of the Keweenawan Midcontinent Rift. The ECRB extends from central Michigan at least as far south as south-central Kentucky. The inferred age of the rift fill is approximately 1,000 Ma. Evidence supporting a rift origin for the ECRB includes: interbedding of continental flood basalts and felsic volcanics with siliciclastics; sedimentary fill consisting of distal, arid-climate alluvial fan sediments that lack metamorphic lithologies; close proximity and similar lithologic succession to the Keweenawan rift-fill rocks of the Michigan Basin; and inferred marginal block faulting of Granite-Rhyolite Province rocks near the western edge of the ECRB. ECRB evolution is interpreted as follows: (1) formation of Granite-Rhyolite Province rocks (1,500--1,340 Ma); (2) Keweenawan crustal extension and rifting with development of central mafic complexes, emplacement of volcanic rocks, and deposition of siliciclastic fill from eroded marginal Granite-Rhyolite Province tilted fault blocks (ca 1,000 Ma); (3) overthrusting of the Grenville allochthon and associated foreland thrusting and folding of the rift sequence rocks together with deposition of foreland basin sediments (975---890 Ma); (4) Late Proterozoic erosional removal of the foreland basin sediments and interpreted wrench faulting along the Grenville Front (post-975 to pre-570 Ma); and (5) tectonic inversion, with the ECRB area remaining relatively high during major cambrian subsidence in central Kentucky (590--510 Ma).

  19. Cenozoic North American Drainage Basin Evolution, Sediment Yield, and Accumulation in the Gulf of Mexico Basin

    NASA Astrophysics Data System (ADS)

    Galloway, W.; Ganey-Curry, P. E.

    2010-12-01

    The Cenozoic fill of the Gulf of Mexico basin contains a continuous record of sediment supply from the North American continental interior for the past 65 million years. Regional mapping of unit thickness and paleogeography for 18 depositional episodes defines patterns of shifting entry points of continental fluvial systems and quantifies the total volume of sediment supplied during each episode. Eight fluvio-deltaic depocenters, named for geographic similarities to entry points and drainage basins of modern rivers, are present. From southwest to northeast, they are the Rio Bravo, Rio Grande, Guadalupe, Colorado, Houston-Brazos, Red, Mississippi, and Tennessee axes. Sediment volume was calculated from hand-contoured unit thickness maps compiled from basin-wide well and seismic control. Using a GIS algorithm to sum volumes within polygons bounding interpreted North American river contribution, the total extant volume was then calculated. General compaction factors were used to convert modern volume to quantitative approximations of total grain volume. Grain volume rate of supply for each depositional episode was then calculated. Values vary by more than an order of magnitude. Supply rate has commonly varied by two-fold or more between successive depositional episodes. Sediment supply is a significant, independent variable in development of stratigraphic sequences within the Gulf basin. Paleogeographic maps of the continental interior for eleven Cenozoic time intervals display the evolving and complex interplay of intracontinental tectonism, climate change, and drainage basin evolution. Five tectono-climatic eras are differentiated: Paleocene late Laramide era; early to middle Eocene terminal Laramide era; middle Cenozoic (Late Eocene—Early Miocene) dry, volcanogenic era; middle Neogene (Middle—Late Miocene) arid, extensional era; and late Neogene (Plio—Pleistocene) monsoonal, epeirogenic uplift era. Sediment supply to the GOM reflects the interplay of (1) areal extent of river drainage basins, (2) source area relief, (3) climate of the source areas and tributary systems, (4) source lithology, and (5) sediment storage within the upper drainage basin. Climate has played an important and complex role in modulating supply. In wet tropical to temperate climate regimes, abundant runoff efficiently removed entrained sediment. Arid climate limited runoff; resultant transport-limited tributaries and trunk streams deposited aggradational alluvial aprons, storing sediment in the drainage basin even in the absence of a structural depression. Eolian deposition commonly accompanied such alluvial aggradation. In contrast, seasonality and consequent runoff variability favored erosion and efficient sediment evacuation from the upper parts of drainage basins. Tectonism has played a prominent but equally complex role. Elevation of uplands by compression, crustal heating, or extrusive volcanism created primary loci of erosion and high sediment yield. At the same time, accompanying subsidence sometimes created long-lived sediment repositories that intercepted and sequestered sediment adjacent to sources. Regional patterns of uplift and subsidence relocated drainage divides and redirected trunk stream paths to the Gulf margin.

  20. Aggradation-incision transition in arid environments at the end of the Pleistocene: An example from the Negev Highlands, southern Israel

    NASA Astrophysics Data System (ADS)

    Faershtein, Galina; Porat, Naomi; Avni, Yoav; Matmon, Ari

    2016-01-01

    One of the most significant environmental processes that occurred at the transition from the last glacial phase into the present inter-glacial phase in arid regions was the shift from aggradation to incision in the drainage systems. This is evident by the sharp transition from a fluvial regime depositing fine-grained sediment within the wadis to intensive incision which formed gullies and narrow channels that dissected the late Pleistocene sediments. In order to investigate this transition, we studied three small-scale basins in the arid region of the Negev Highlands, southern Israel. Although the selected basins drain toward different base levels, their geomorphological parameters, particle size distribution of alluvial units and their OSL ages are similar. Sediments from the penultimate glacial cycle are found in patches in the bigger catchments. Fluvial loess was widely deposited since at least 67 ka until after 28 ka, covering valleys and slopes. Between ~ 28 and ~ 24 ka, loess was washed from the slopes into the channels, exposing the underlying colluvium. At ~ 24 ka erosion began with the transport of slope colluvium as gravels into the valleys that eroded the underlying loess sediments. Incision became dominant at ~ 12 ka and is still ongoing and intensifying. Dust and reworked loess continued to be deposited during the main incision stages. It is proposed that the transition from aggradation to incision was controlled by rates of loess supply and removal. Until ~ 24 ka dust choked the drainage system and only after reduction in dust supply was erosion and incision possible. It began first on the slopes and then in the channels. Our results show that an increase in precipitation is not a prerequisite for initiation of incision as is often assumed. Similar processes are described in other arid zones around the world.

  1. Changing Nitrate Concentrations in Arid Basin Aquifers- How Anthropogenic and Natural Processes Affect Water Quality and Availability in Trans-Pecos, TX

    NASA Astrophysics Data System (ADS)

    Robertson, W. M.; Bohlke, J. K.; Sharp, J. M.

    2012-12-01

    For the past six decades nitrate concentrations in groundwater of the West Texas Bolson Aquifers have been increasing. Long-term records (from 1950 to present) indicate an average increase of 3-5 mg/L (as nitrate) with some wells increasing by over 40 mg/L within 1-2 decades. While irrigated agriculture is the second largest land use in the region (range land being the largest), isotopic analyses indicate that direct leaching of synthetic fertilizers is not a primary source of nitrate to the groundwater; the isotopic composition of the nitrate in the groundwater (delta 18-O of +2 to +10 per mil and delta 15-N of +6 to +13 per mil) is more similar to that of natural soil-derived nitrate in the region, or possibly manure-derived nitrate. Various anion ratios (chloride/bromide, nitrate/chloride, and nitrate/bromide) provide additional insight into the likely sources of groundwater nitrate and the mechanisms by which it is transported through the unsaturated zone; compared to atmospheric deposition, groundwater N/Cl and N/Br ratios appear to be relatively low, consistent with net N loss accompanied by relatively high delta 15-N of residual N. The observed decadal scale changes in groundwater nitrate concentration and presence of young (<70 year old) recharge (as measured using CFCs) are coincident with the growth of irrigated agriculture and intensive grazing within the basins. We hypothesize that past and present land use practices have contributed to the increase in nitrate in the groundwater in three ways; 1) plowing and grazing of previously undisturbed grasslands led to mobilization of soil nitrogen, 2) irrigation of crops has increased recharge beneath agricultural fields and mobilized naturally occurring nitrate from the unsaturated zone, and 3) deposition of manure by grazing animals may have contributed to high delta 15-N values, and in the case of now disused CAFO operations (confined feed lots) may have contributed locally to the total mass of reactive nitrogen. These effects are likely temporally and spatially variable, but have a substantial impact on strategies for addressing water quality and sustainability concerns in these basins and similar environments elsewhere.

  2. Impact and sustainability of low-head drip irrigation kits, in the semi-arid Gwanda and Beitbridge Districts, Mzingwane Catchment, Limpopo Basin, Zimbabwe

    NASA Astrophysics Data System (ADS)

    Moyo, Richard; Love, David; Mul, Marloes; Mupangwa, Walter; Twomlow, Steve

    Resource-poor smallholder farmers in the semi-arid Gwanda and Beitbridge districts face food insecurity on an annual basis due to a combination of poor and erratic rainfall (average 500 mm/a and 345 mm/a, respectively, for the period 1970-2003) and technologies inappropriate to their resource status. This impacts on both household livelihoods and food security. In an attempt to improve food security in the catchment a number of drip kit distribution programmes have been initiated since 2003 as part of an on-going global initiative aimed at 2 million poor households per year. A number of recent studies have assessed the technical performance of the drip kits in-lab and in-field. In early 2005 a study was undertaken to assess the impacts and sustainability of the drip kit programme. Representatives of the NGOs, local government, traditional leadership and agricultural extension officers were interviewed. Focus group discussions with beneficiaries and other villagers were held at village level. A survey of 114 households was then conducted in two districts, using a questionnaire developed from the output of the interviews and focus group discussions. The results from the study showed that the NGOs did not specifically target the distribution of the drip kits to poor members of the community (defined for the purpose of the study as those not owning cattle). Poor households made up 54% of the beneficiaries. This poor targeting of vulnerable households could have been a result of conditions set by some implementing NGOs that beneficiaries must have an assured water source. On the other hand, only 2% of the beneficiaries had used the kit to produce the expected 5 harvests over the 2 years, owing to problems related to water shortage, access to water and also pests and diseases. About 51% of the respondents had produced at least 3 harvests and 86% produced at least 2 harvests. Due to water shortages during the dry season 61% of production with the drip kit occurred during the wet season. This suggests that most households use the drip kits as supplementary irrigation. Conflicts between beneficiaries and water point committees or other water users developed in some areas especially during the dry season. The main finding from this study was that low cost drip kit programs can only be a sustainable intervention if implemented as an integral part of a long-term development program, not short-term relief programs and the programme should involve a broad range of stakeholders. A first step in any such program, especially in water scarce areas such as Gwanda and Beitbridge, is a detailed analysis of the existing water resources to assess availability and potential conflicts, prior to distribution of drip kits.

  3. Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin.

    PubMed

    Pell, Albert; Márquez, Anna; López-Sánchez, José Fermín; Rubio, Roser; Barbero, Mercedes; Stegen, Susana; Queirolo, Fabrizio; Díaz-Palma, Paula

    2013-01-01

    This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp. PMID:22981629

  4. Geomorphic Processes and Remote Sensing Signatures of Alluvial Fans in the Kun Lun Mountains, China

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Chadwick, Oliver A.

    1996-01-01

    The timing of alluvial deposition in arid and semiarid areas is tied to land-surface instability caused by regional climate changes. The distribution pattern of dated deposits provides maps of regional land-surface response to past climate change. Sensitivity to differences in surface roughness and composition makes remote sensing techniques useful for regional mapping of alluvial deposits. Radar images from the Spaceborne Radar Laboratory and visible wavelength images from the French SPOT satellite were used to determine remote sensing signatures of alluvial fan units for an area in the Kun Lun Mountains of northwestern China. These data were combined with field observations to compare surface processes and their effects on remote sensing signatures in northwestern China and the southwestern United States. Geomorphic processes affecting alluvial fans in the two areas include aeolian deposition, desert varnish, and fluvial dissection. However, salt weathering is a much more important process in the Kun Lun than in the southwestern United States. This slows the formation of desert varnish and prevents desert pavement from forming. Thus the Kun Lun signatures are characteristic of the dominance of salt weathering, while signatures from the southwestern United States are characteristic of the dominance of desert varnish and pavement processes. Remote sensing signatures are consistent enough in these two regions to be used for mapping fan units over large areas.

  5. Use of TOPSAR digital elevation data to determine the 3-dimensional shape of an alluvial fan

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.

    1995-01-01

    Landforms in arid regions record the interplay between tectonic forces and climate. Alluvial fans are a common landform in desert regions where the rate of uplift is greater than weathering or sedimentation. Changes in uplift rate or climatic conditions can lead to isolation of the currently forming fan surface through entrenchment and construction of another fan either further from the mountain front (decreased uplift or increased runoff) or closer to the mountain front (increased uplift or decreased runoff). Thus, many alluvial fans are made up of a mosaic of fan units of different age, some older than 1 million years. For this reason, determination of the stages of fan evolution can lead to a history of uplift and runoff. In an attempt to separate the effects of tectonic (uplift) and climatic (weathering, runoff, sedimentation) processes on the shapes of alluvial fan units, a modified conic equation developed by Troeh (1965) was fitted to TOPSAR digital topographic data for the Trail Canyon alluvial fan in Death Valley, California. This allows parameters for the apex position, slope, and radial curvature to be compared with unit age.

  6. Lake Urmia (Iran): can future socio-ecologically motivated river basin management restore lake water levels in an arid region with extensive agricultural development?

    NASA Astrophysics Data System (ADS)

    Fazel, Nasim; Berndtsson, Ronny; Bertacchi Uvo, Cintia; Klove, Bjorn; Madani, Kaveh

    2015-04-01

    Lake Urmia, one of the world's largest hyper saline lakes located in northwest of Iran, is a UNESCO Biosphere Reserve and Ramsar site, protected as a national park and, supports invaluable and unique biodiversity and related ecosystem services for the region's 6.5 million inhabitants. Due to increased development of the region's water resources for agriculture and industry and to a certain extent climate change, the lake has started to shrink dramatically since 1995 and now is holding less than 30 percent of its volume. Rapid development in agricultural sector and land-use changes has resulted in immense construction of dams and water diversions in almost all lake feeding rivers, intensifying lake shrinking, increasing salinity and degrading its ecosystem. Recently, lake's cultural and environmental importance and social pressure has raised concerns and brought government attention to the lake restoration plans. Along with poor management, low yield agriculture as the most water consuming activity in the region with, rapid, insufficient development is one of the most influential drivers in the lake desiccation. Part of the lake restoration plans in agricultural sector is to restrict the agricultural areas in the main feeding river basins flowing mostly in the southern part of the lake and decreasing the agricultural water use in this area. This study assess the efficiency and effectiveness of the proposed plans and its influence on the lake level rise and its impacts on economy in the region using a system dynamics model developed for the Lake consist of hydrological and agro-economical sub-systems. The effect of decrease in agricultural area in the region on GDP and region economy was evaluated and compared with released water contribution in lake level rise for a five year simulation period.

  7. Tectonic Versus Climatic Controls On Alluvial Systems: New Insights Into Sediment Flux From Central Spain

    NASA Astrophysics Data System (ADS)

    Hall, P.; Jones, S. J.

    Sediment flux to a basin is a primary first order control on sequence stratigraphic architecture, acting as a control on far reaching intra -basinal sedimentation. The rate of uplift, sediment flux, gradient, outlet spacing along a basin margin are important primary parameters controlling sediment distribution from source to sink. Consequently, a quantitative and qualitative understanding of how drainage systems operate, over geomorphological and geological time -scales, in differing tectonic and climatic settings is of fundamental imp ortance for basin fill and landscape modelling. The most obvious and easily accessible setting for appreciating sediment supply and geometries along the margin of a basin in through the detailed evaluation of alluvial fans. Detailed facies analysis, provenance reconstructions, fan development evolution, tectonic framework history and theoretical modelling of fan progradation are utilised for Triassic alluvial fans of the Central Iberian Ranges of central Spain. These alluvial fans clearly display the difficulties in differentiating between tectonic and climatic sedimentary signatures. However, recent detailed studies have revealed the interbedded nature of fine-grained sandstones and coarse fluvial dominated gravel which characterise the fan deposits. The boundaries of each facies are sharp, laterally extensive, illustrate little to no reworking, and in turn, poorly developed paleosols can be found draping over the coarse fan sediments. These characteristics can not be easily explained by tectonic readjustment of the fan or drainage basin. It is clear that the coarse sediments were deposited by high magnitude, low frequency flood events controlled by climate. This research illustrates the importance of climate driving sediment supply to the basin, once a sediment routing system has been established. It is always tempting to interpret coarse sediment influx in ancient basin settings as indicative of renewed tectonism. However, the examples from the Triassic central Iberian rift basin of Spain demonstrate that climate is just as likely to control sediment flux to a fan, and into a basin. This study offers new insights into the interpretation of alluvial fans at tectonically basin margins and how sediment is redistributed into basin centres, previously neglected in the literature.

  8. Changes in soil organic carbon and nitrogen capacities of Salix cheilophila Schneid along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jia, Z. Q.

    2014-11-01

    The Gonghe Basin is a sandified and desertified region of China, but the distribution of soil organic carbon (SOC) and total nitrogen (TN) along the cultivation chronosequence across this ecologically fragile region is not well understood. This study was carried out to understand the effects of restoration with Salix cheilophila for different periods of time (6, 11, 16, 21 years) to test whether it enhanced C and N storage. Soil samples, in four replications from seven depth increments (0-10, 10-20, 20-30, 30-50, 50-100, 100-150 and 150-200 cm), were collected in each stand. Soil bulk density, SOC, TN, aboveground biomass and root biomass were measured. Results indicated that changes occurred in both the upper and deeper soil layers with an increase in revegetation time. The 0-200 cm soil showed that the 6-year stand gained 3.89 Mg C ha-1 and 1.00 Mg N ha-1, which accounted for 40.82% of the original SOC and 11.06% of the TN of the 0-year stand. The 11-year stand gained 7.82 Mg C ha-1 and 1.98 Mg N ha-1 in the 0-200 cm soil layers, accounting for 58.06% of the SOC and 19.80% of the TN of the 0-year stand. The 16-year stand gained 11.32 Mg C ha-1 and 3.30 Mg N ha-1 in the 0-200 cm soil layers, accounting for 66.71% of the SOC and 21.98% of the TN of the 0-year stand. The 21-year stand gained 13.05 Mg C ha-1 and 5.45 Mg N ha-1 from the same soil depth, accounting for 69.79% of the SOC and 40.47% of the TN compared with the 0-year stand. The extent of these changes depended on soil depth and plantation age. The results demonstrated that, as stand age increased, the storage of SOC and TN increased. These results further indicated that restoration with S. cheilophila has positive impacts on the Gonghe Basin and has increased the capacity of SOC sequestration and N storage. The shrub's role as carbon sink is compatible with system management and persistence. The findings are significant for assessing C and N sequestration accurately in semi-arid degraded high, cold sandy regions in the future.

  9. Changes in soil organic carbon and nitrogen capacities of Salix cheilophila Schneid along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jia, Q. Z.

    2014-08-01

    The Gonghe Basin is a sandified and desertified region of China, but the distribution of soil organic carbon (SOC) and total nitrogen (TN) along the cultivation chronosequence across this ecologically fragile region is not well understood. This study was carried out to understand the effects of afforestation with Salix cheilophila for different periods of time (6, 11, 16, 21 years) to test whether it enhanced C and N storage. Soil samples, in four replications from seven depth increments (every 10 cm from 0 to 30 cm, every 20 cm from 30 to 50 cm and every 50 cm from 50 to 200 cm), were collected in each stand. Soil bulk density, SOC, TN, aboveground biomass and root biomass were measured. Results indicated that changes occurred in both the upper and deeper soil layers with an increase in revegetation time. The 0-200 cm soil showed that the 6-year stand gained 3.89 Mg C ha-1 and 1.00 Mg N ha-1, which accounted for 40.82% of the original SOC and 11.06% of the TN of the 0-year stand. The 11-year stand gained 7.82 Mg C ha-1 and 1.98 Mg N ha-1 in the 0-200 cm soil layers, accounting for 58.06% of the SOC and 19.80% of the TN of the 0-year stand. The 16-year stand gained 11.32 Mg C ha-1 and 3.30 Mg N ha-1 in the 0-200 cm soil layers, accounting for 66.71% of the SOC and 21.98% of the TN of the 0-year stand. The 21-year stand gained 13.05 Mg C ha-1 and 5.45 Mg N ha-1 from the same soil depth, accounting for 69.79% of the SOC and 40.47% of the TN compared with the 0-year stand. The extent of these changes depended on soil depth and plantation age. The results demonstrated that as stand age increased, the storage of SOC and TN increased. These results further indicated that afforestation with S. cheilophila has positive impacts on the Gonghe Basin and has increased the capacity of SOC sequestration and N storage. Shrub's role as carbon sink is compatible with system's management and persistence. The findings are significant for assessing C and N sequestration accurately in semi-arid degraded high-cold sandy regions in the future.

  10. Modern and ancient alluvial fan deposits

    SciTech Connect

    Nilsen, T.H.

    1985-01-01

    Understanding the structure and depositional processes of alluvial fans (river outwash deposits) has a special interest for those involved with the exploration of petroleum and many minerals. This collection of facsimile reprints of significant and classical research papers sheds new light on the subject. This reference covers the stratigraphy, sedimentology, and depositional processes of modern and ancient alluvial fans. Geographical areas considered include Arctic Canada, the American Southwest, Australia, Wyoming, Norway, and Spain. It includes a state-of-the-art introduction by the editor along with commentaries on all the papers included, a master author citation index and a subject index, and a chronological listing of early studies of alluvial fans.

  11. Carbonates in alluvial fan systems. An approach to physiography, sedimentology and diagenesis

    NASA Astrophysics Data System (ADS)

    Nickel, Enno

    1985-01-01

    This paper deals with the modes of accumulation and distribution of terrestrial carbonates in semi-arid alluvial-fluvial, generally clastic sedimentary environments. It is shown that composition and distribution of the carbonate phases are controlled by physical (transportation energy), morphological (slope gradient), chemical (precipitation, evaporization) processes and biochemical interaction with the respective subenvironment of mainly cyanophytes. Evaluation of recent and fossil examples from semi-arid alluvial settings indicate that the physical processes produce carbonate sequences which, like the clastic ones, are fining-upward, corresponding to the intermittently active sedimentation on an alluvial fan. The mineralogy of the carbonates seems to depend upon disproportioning of dissolved compounds in subsurface waters in down-fan directions. There is obviously a shift towards more "evaporitic" minerals in the distal parts in favour of high-Mg-calcite, dolomite or even gypsum. Biochemical carbonate production is in direct correspondence with the respective sedimentary subenvironment. In terms of transport energy and sediment supply there is evidence that high-energy (proximal) regimes are producing isolated biosedimentary structures, whereas low energy areas (distal, interchannel, floodplains) are favourable for continuous structures like algal stromatolites and algal mats. A newly proposed classification system based upon transport/precipitation mode and sediment type is thought to be more useful for environmental analysis and reconstructions than purely descriptive ones neglecting the process of formation. This is especially the case for the non-active phases of alluvial fans when the area of deposition is sediment-starved, referring to the clastics. The system takes into account that there are two general carbonate groups: detrital allochthonous and chemical/biochemical autochthonous ones. The latter may be formed within the pores of the clastic sediments or may be due to sedimentation in open water. Pedogenic processes may themselves be the carbonate-forming factor or they may "superprint" non-pedogenic processes.

  12. Characterization of dust emission from alluvial sediments using aircraft observations and modeling

    NASA Astrophysics Data System (ADS)

    Schepanski, K.; Flamant, C.; Chaboureau, J.; Kocha, C.; Banks, J.; Brindley, H. E.; Lavaysse, C.; Marnas, F.; Pelon, J.; Tulet, P.

    2013-12-01

    Recent studies using satellite observations show that numerous dust sources are located in the foothills of arid and semi-arid mountain regions such as over North Africa. Alluvial sediments deposited on the valley bottoms and flood plains are very prone to wind erosion and frequently serve as dust source. High surface wind speeds related to the break-down of the nocturnal low-level jet (LLJ) during the morning hours are identified as a frequent driving mechanism for dust uplift. We investigate dust emission from alluvial dust sources located within the upland region in northern Mauritania and discuss the impact of valleys with regard to their role as dust source. Measures for local atmospheric dust burden were retrieved from airborne observations, MSG SEVIR dust AOD fields and MesoNH model simulations, and analyzed in order to provide complementary information on dust source activation and local dust transport at different horizontal scales. Vertical distribution of atmospheric mineral dust was obtained from the LNG backscatter lidar system flying aboard the French Falcon-20 aircraft. Lidar extinction coefficients were compared to topography, aerial photographs, and dust AOD fields to confirm the relevance of alluvial sediments at the valley bottoms as dust source. The observed dust emission event was further evaluated using the regional model MesoNH. A sensitivity study on the impact of the horizontal grid spacing highlights the importance of the spatial resolution on simulated dust loadings. The results further illustrate the importance of an explicit representation of alluvial dust sources in such models to better capture the spatial-temporal distribution of airborne dust concentrations.

  13. Geoenvironmental and structural studies for developing new water resources in arid and semi-arid regions using remote sensing and GIS

    NASA Astrophysics Data System (ADS)

    Amer, Reda Mohammed

    2011-12-01

    Water crises are rising with increasing world population and decreasing of freshwater resources. This problem is magnified in the arid and semi-arid regions because surface water resources are very limited and highly unreliable and therefore groundwater is the primary source of water supply in these regions. This study presents an integrated approach for the identification of groundwater occurrences using remote sensing, geological, and geophysical data, and establishing sustainable paths to groundwater management. The Central Eastern Desert (CED) of Egypt was selected as a test site for this study because its climate is arid and there is an urgent need to identify potential areas for groundwater accumulations. Field investigations indicated that the CED has three types of aquifers; shallow alluvial (SA), and fracture zone (FZ) aquifers in the valley depressions, and deep aquifers in the sedimentary succession that range in age from Late Cretaceous to Recent in the marginal extensional sub-basins (ESB) along the Red Sea coast. I developed three models: (1) a Geographic Information System (GIS) model for groundwater potential in the SA and FZ shallow aquifers; (2) a kinematic model for the development of the ESB; and (3) a groundwater budget model for the ESB aquifers. The GIS model is based on the analysis of remote sensing data of the Phased Array L-band Synthetic Aperture Radar, the Landsat Enhanced Thematic Mapper Plus, and the Advanced Spaceborne Thermal Emission and Reflection Radiometer digital elevation model. The model was evaluated and proven successful against the existing shallow water wells, and by geophysical surveys using Ground Penetrating Radar and Geoelectric methods. The kinematic model indicated that the ESB were formed in the orthogonal rifting phase in the late Oligocene that is followed by oblique rifting phase during the early Miocene which resulted to the en-echelon pattern of the inland ESB and nucleation of the rift depression into segments separated by oblique-slip accommodation zones. The groundwater budget model shows that the ESB aquifers have considerable amounts of paleowater that can be purified and used for drinking. The renewable groundwater of SA and FZ aquifers can be used for herding, irrigation, and ore dressing in the mining zones.

  14. Bedrock versus alluvial channel geometry

    NASA Astrophysics Data System (ADS)

    Church, M. A.; Venditti, J. G.; Rennie, C. D.

    2012-12-01

    We present observations of channel geometry obtained on a 524 km long continuous traverse of Fraser River, British Columbia, Canada, as it passes through the Fraser canyons. The channel alternates between gravel-bedded reaches that are incised into semi-consolidated glacial deposits and bedrock-bound reaches (7.7% of the reach above Hope). We obtained data of 71 cross-sections using 600 kHz and 1200 kHz aDcp and, in addition, obtained measures of channel width from Google® imagery at 0.5 km spacing throughout the traverse. To homogenize the data of sectional geometry along the river (to compensate increasing flows at tributary junctions), we computed w/Q^1/2 and d/Q^1/3, following commonly observed scaling relations. For the sounded cross sections Q is the recorded flow at the time of the survey; for the map measurements, Q is mean annual flood for the reach, leading to some difference between the two sets of statistics. From the more abundant map data, alluvial reaches are 2.3x wider than and, from soundings, 0.60 as deep as rock-bound reaches, implying that mean velocity is accelerated in rock reaches by 38%. These data are based on section averages: extremes of depth and velocity in rock canyons are substantially greater. There is also variation from reach to reach along the river controlled by variation in rock lithologies, with the narrowest canyons occurring in Fraser Canyon proper (w/Q^1/2 = 0.083 compared with 1.4 elsewhere). The uppermost ('Marguerite') and lowermost ('Agassiz') alluvial reaches are considerably wider (w/Q^1/2 = 3.9 and 7.1 respectively) than intervening ones (~2.35). These reaches have lower gradients and exhibit wandering channels. Because of lithological control, the downstream hydraulic geometry of the river does not, in fact, conform with the common pattern, even when sections are analyzed according to boundary material. However, river gradient is well correlated with scaled width, inversely for gravel reaches and directly, but with little sensitivity for rock-bound reaches. We show distributions of channel width and depth along the river.

  15. Morphometric Characterization and Classification of Alluvial Fans in Eastern Oman

    NASA Astrophysics Data System (ADS)

    Leuschner, Annette; Mattern, Frank; van Gasselt, Stephan

    2015-04-01

    Morphologic characteristics of alluvial fans are a product of fluvial erosion, transportation and deposition. Consequently, fans have been described and defined on the basis of their shape, their composition, conditions and processes under which they from, their so-called "controlling factors", and their geomorphic and tectonic settings. The aim of our study is to reconstruct the morphologic evolution and to relate it to past and present climate conditions. In order to achieve this, we first characterize alluvial fans based on their climatic settings and conditions and classify them accordingly using satellite image data and digital elevation models. For mapping of different alluvial fan bodies multispectral images of the Landsat Enhanced Thematic Mapper (ETM+) with a scale of 15-30 m/px were utilized. For the detection of morphometric parameters as input data for subsequent hydrological studies digital terrain model data of the Shuttle Radar Topography Mission (SRTM) and the ASTER GDEM with a scale of 90 m/px and 30m, respectively, were used. Using these datasets morphological characteristics, such as sizes of drainage basins, transport areas and areas of deposition derived from spatial semi-automatic analysis, have been computed. The area of Muscat at the Oman Mountains has been selected as a study area because of its size, accessibility and climate conditions and it is considered well-suited for studying the development of alluvial fans and their controlling factors. The Oman Mountains are well-known for the world's largest intact and best exposed obducted ophiolite complex, the Semail Ophiolite. They are today subjected to a mild desert climate (Bwh), influenced by the Indian Ocean but they have experienced extensive pluvial periods in the geologic past. Formation of alluvial fans was, therefore, likely triggered by the interplay of increased sediment production caused by high rainfalls with enhanced erosion of hillslopes and transport rates during pluvial periods. Typical morphometric parameters controlled by hydrological conditions are sizes of catchment areas, the morphometry of associated rivers and slope angles as well as sizes of alluvial fans. In order to distinguish the catchment areas, semi-automatized spatial analyses based on DEM data were carried out within a commercial GIS environment. Our analyses generally verify that there is a positive correlation between, e.g., fan areas and sizes of catchment areas as well as between fan areas and lengths of valley lines of associated rivers. Furthermore, our analyses show a negative correlation between average fan slopes and sizes of catchment areas. The observations are in good agreement with previous analyses from other areas we conducted. The applied methodology has shown to be adequate to be compared to and combined with future field investigations. Flow events are dominant in fan evolution, but the way in which alluvial fan systems responded to fluvial environmental conditions differs between systems under different climate conditions. We compared our results with data from other places located in different climate zones around the world. This allows us to constrain boundary conditions and their potential influence on shapes in a more efficient way.

  16. Application of the groundwater-balance equation to indicate interbasin and vertical flow in two semi-arid drainage basins, Mexico

    NASA Astrophysics Data System (ADS)

    Carrillo-Rivera, J. J.

    2000-09-01

    An analysis of horizontal inflow and outflow in the groundwater-budget equation and the significance for interbasin flow are presented. Two field cases in Mexico, one in the Baja California peninsula and another in central Mexico, highlight the influence of interbasin flow. A significant proportion (approximately 70%) of the ed (thermal) groundwater probably originates outside the drainage basin. A conclusion is that a groundwater-balance study is an unsatisfactory method for determining some parameters, such as storativity (S). Specifically, the groundwater-balance approach provides unreliable results when vertical inflow is ignored or cannot be adequately defined. Vertical flow is indicated by the presence of groundwater temperatures as much as 23 °C higher than ambient temperature. Regional faults could be the pathways for upward flow. When vertical inflow is ignored, uncertainty in the estimation of the storativity through regional groundwater-balance calculation results. On the basis of the groundwater-balance equation, a value of S=0.19 appears to represent the confined condition of the developed part of the aquifer; this result is several orders of magnitude higher than would be reasonable according to the geological conditions. Findings are useful in evaluating whether a groundwater resource is being "overexploited". Conclusions are instructive in the application of transient-flow computer models, in which vertical flow of less dense water from beneath is not included. Résumé. L'article présente une analyse des entrées et des sorties horizontales dans l'équation du bilan d'une nappe et leur signification dans les écoulements entre bassins. Deux exemples provenant du Mexique, l'un dans la péninsule de Basse Californie, l'autre dans le centre du Mexique, mettent en lumière l'influence de l'écoulement entre bassins, où une proportion significative (environ 70%) de l'eau souterraine extraite, thermale, a probablement son origine hors du bassin. Une conclusion est qu'une étude par bilan de la nappe est une méthode qui n'est pas satisfaisante pour déterminer certains paramètres comme le coefficient d'emmagasinement. En particulier, l'approche par le bilan de la nappe donne des résultats qui ne sont pas fiables lorsque l'on ignore la drainance verticale ou que l'on ne peut pas la définir correctement. L'existence d'une drainance verticale est prouvée par des températures de l'eau souterraine pouvant être supérieures de 23 °C à la température ambiante. Des failles régionales peuvent permettre ces écoulements vers le haut. Lorsque l'on ignore la drainance verticale, on introduit une incertitude sur l'estimation de l'emmagasinement à partir des calculs du bilan régional de la nappe. Sur la base de l'équation du bilan de la nappe, une valeur de S=0,19 semble représenter les conditions captives de la partie développée de l'aquifère ce résultat est plus élevé, de plusieurs ordres de grandeur, que celui que l'on peut raisonnablement attendre des conditions géologiques. Ces résultats sont utiles pour évaluer si une ressource en eau souterraine est "surexploitée". Ces conclusions sont intéressantes lorsque l'on applique des modèles d'écoulement transitoire dans lesquels on ne prend pas en compte la drainance verticale d'une eau plus légère remontant. Resumen. En este trabajo, se investigan las entradas y salidas de flujo horizontal en la ecuación de balance de agua subterránea, así como el papel que desempeñan en el flujo entre cuencas. Se analizan dos ejemplos de México, uno en la Península de Baja California y otro en la parte central del país. En ambos, destaca la influencia del flujo entre cuencas, ya que se estima que una parte importante (aproximadamente el 70%) del agua termal extraída procede de una cuenca superficial externa. Se concluye que el método basado en cálculos de balance de agua subterránea no es satisfactorio para determinar algunos parámetros, como, por ejemplo, el coeficiente de almacenamiento (S). En particular, la ecuación de balance de agua subterránea proporciona resultados poco fiables cuando el flujo vertical es ignorado o no puede ser evaluado de forma adecuada. El flujo vertical se identifica por un incremento de temperatura del agua subterránea, que puede llegar a superar la temperatura ambiental en hasta 23 °C. La presencia de fallas regionales y las extracciones pueden favorecer el flujo vertical. Cuando éste es ignorado, aumenta la incertidumbre en la estimación del coeficiente de almacenamiento mediante un balance de agua subterránea. El valor obtenido con este médodo (S=0,19) es característico de acuíferos libres, pero resulta varios órdenes de magnitud mayor que el que sería esperable teniendo en cuenta las condiciones hidrogeológicas. Estos hallazgos son útiles para evaluar si los recursos de agua subterránea están siendo "sobreexplotados". Las conclusiones obtenidas son instructivas de cara a la aplicación de modelos numéricos de flujo transitorio que no consideran el flujo vertical por densidad.

  17. Dependable water supplies from valley alluvium in arid regions.

    PubMed

    Van Haveren, Bruce P

    2004-12-01

    Reliable sources of high-quality water for domestic use are much needed in arid regions. Valley alluvium, coarse sand and gravel deposited by streams and rivers, provides an ideal storage medium for water in many regions of the world. However, river sediments will not accumulate in a valley without a natural or artificial barrier to slow the water. Sediments will deposit upstream of a barrier dam and form an alluvial deposit of relatively well-sorted material. The alluvium then acts as both an underground water-supply reservoir and a water filter, yielding a constant flow of high-quality water. Trap dams that store water in alluvial sediments and slowly release the filtered water represent an appropriate and inexpensive technology for combating desertification and mitigating the effects of drought at the community level. Small trap dams may be built as a community project using local materials and local labor. PMID:15641388

  18. Use of morphometric analysis and self-organizing maps for alluvial fan classification: case study on Ostorankooh altitudes, Iran

    NASA Astrophysics Data System (ADS)

    Mokarram, Marzieh; Seif, Abdollah; Sathyamoorthy, Dinesh

    2014-06-01

    The aim of this study is to classify alluvial fans formed by high-gradient braided streams and torrents that discharge into the Oshtorankook altitudes in the Lorestan province, Iran. The morphology of the fans and their watershed is quantitatively described through estimated morphometric parameters. For relationships between geomorphological features of the fans and their drainage basins, self-organizingmaps (SOM) were used. In SOM, according to both qualitative data and morphometric variables, the clustering tendency of alluvial fans was investigated using 15 alluvial fans parameters. The results of the analysis showed that several morphologically different fan types were recognizedbased on their geomorphological characteristics in the study area. A strong positive relationship was found between the drainage basin area and size of the fan with a simple power function. In addition, the relationship between fan slope and drainage area was found to be negative and moderately strong with a simple power function.

  19. Investigating Source to Sink Processes with Cosmogenic 10Be Concentrations in Multiple Alluvial Grain Sizes

    NASA Astrophysics Data System (ADS)

    Marstellar, T. L.; Frankel, K. L.; Belmont, P.

    2010-12-01

    Recent studies suggest that concentrations of terrestrial cosmogenic nuclides (TCN) in varying grain sizes can provide important information about sediment source to sink pathways. However, some basic questions remain regarding the role that geomorphic processes play in determining TCN concentrations in alluvial sediment. As a result, there exists a critical need for an increased understanding of how sediment transport histories effect the interpretation of TCN concentrations in alluvium, and hence, the denudation rates and surface exposure ages derived from these data sets. We are using 10Be TCN concentrations in various alluvial sediment grain sizes to investigate the geomorphic processes responsible for eroding and transporting sediments from hillslopes, through drainage networks, and ultimately to sedimentary depocenters in two contrasting tectonic and climatic environments. The first is Red Wall Canyon in northern Death Valley, California, an arid tectonically active region. The second is the Blue Ridge Escarpment in the southern Appalachian Mountains, a humid tectonically inactive region. We collected sand (0.025-0.050 cm) and gravel (3-6cm) from active channels within the study areas for analysis of 10Be concentrations in the two distinct grain sizes; 19 samples were collected from Red Wall Canyon and 16 samples from the Blue Ridge Escarpment. By analyzing TCN concentrations in multiple alluvial grain sizes this project will explore the geomorphic processes responsible for transporting sediments from source area to depocenter, determine the geomorphic controls on TCN concentrations among variable grain size fractions in alluvial sediment, and ultimately help establish the most appropriate sample material for dating alluvial fans and measuring catchment-wide denudation rates.

  20. Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

    NASA Astrophysics Data System (ADS)

    de Hamer, W.; Love, D.; Owen, R.; Booij, M. J.; Hoekstra, A. Y.

    Groundwater use by accessing alluvial aquifers of non-perennial rivers can be an important additional water resource in the semi-arid region of southern Zimbabwe. The research objective of the study was to calculate the potential water supply for the upper-Mnyabezi catchment under current conditions and after implementation of two storage capacity measures. These measures are heightening the spillway of the ‘Mnyabezi 27’ dam and constructing a sand storage dam in the alluvial aquifer of the Mnyabezi River. The upper-Mnyabezi catchment covers approximately 22 km 2 and is a tributary of the Thuli River in southern Zimbabwe. Three coupled models are used to simulate the hydrological processes in the Mnyabezi catchment. The first is a rainfall-runoff model, based on the SCS-method. The second is a spreadsheet-based model of the water balance of the reservoir. The third is the finite difference groundwater model MODFLOW used to simulate the water balance of the alluvial aquifer. The potential water supply in the Mnyabezi catchment under current conditions ranges from 2107 m 3 (5.7 months) in a dry year to 3162 m 3 (8.7 months) in a wet year. The maximum period of water supply after implementation of the storage capacity measures in a dry year is 2776 m 3 (8.4 months) and in a wet year the amount is 3617 m 3 (10.8 months). The sand storage dam can only be used as an additional water resource, because the storage capacity of the alluvial aquifer is small. However, when an ephemeral river is underlain by a larger alluvial aquifer, a sand storage dam is a promising way of water supply for smallholder farmers in southern Zimbabwe.

  1. Geological and geochemical characteristics of sedimentary rocks in Kremna, basin (Serbia)

    NASA Astrophysics Data System (ADS)

    Perunović, Tamara; Jovančićević, Branimir; Brčeski, Ilija; Šajnović, Aleksandra; Stojanović, Ksenija; Simić, Vlada; Kašanin-Grubin, Milica

    2014-05-01

    Studying lacustrine sediments is important because of their potential economic value since they often bear coal, oil shales and non-metallic mineral raw materials. Besides this, lacustrine sediments offer valuable information on the climate conditions which existed during the sedimentation. In Serbia there are 14 lacustrine basins spanning in age from Oligocene to Lower Pliocene. The aim of this study was to examine Lower Miocene Kremna basin, located in southwest Serbia. Kremna basin is a small basin, covering 15km2, but sedimentologically very interesting. For the purpose of this study, 43 sediment samples were taken from a borehole at different depths, from surface to 343 m depth of the basin. The borehole ended in weathered serpentinite. Mineralogical composition of sediments was determined using thin-sections and X-ray diffraction analysis, contents of macro-and microelements and rare-earth elements were determined by ICP-ES and ICP-MS techniques. Also, elemental analysis was applied to determine the contents of carbon, sulphur and nitrogen and n-alkanes, isoprenoide aliphatic alkanes and bitumen were also determined using GC-MS technique. Mineralogical analyses proved presents of several lithological types in Kremna basin: clastic sediments, tuffs, tuffaceous sediments, marlstones, dolomites, magnezites, and coal of non-economic value. Occurrence of sirlezite and sepiolite was also determined. Furthermore, according to all obtained results two faciae were determined: alluvial-marginal lacustrine and intrabasinal. Alluvial-marginal facies originated from predominantly ultramafic rocks which underlie the basin. Magnezites and Mg-marls and Mg-dolomites are dominant sediments in this facies. These sediments formed under arid, slightly saline conditions. Intrabasinal facies is represented mostly with marls, Mg-marls and dolomitic limestones. These sediments were deposited under a more humid climate with increase in paleoproductivity. The uppermost sediments of Kremna basin are represented with marly dolomite. Due to the swallowing of the basin sediments became relatively rich in predominantly land plant material. Tuffs and tuffaceous sediments were determined in both faciae.

  2. Geometry and evolution of a syntectonic alluvial fan, Southern Pyrenees

    SciTech Connect

    Arminio, J.F. ); Nichols, G.J. )

    1993-02-01

    Syntectonic alluvial fans formed on the northern margin of the Ebro Foreland Basin along the South Pyrenean thrust front during late orogenic thrust movements in the late Oligocene/early Miocene. The present-day geometry, structural relations and sedimentology of one of these fans, the Aguero fan in the province of Huesca, Spain, were studied. Field observations of the architecture of depositional facies and the geometries of syn-tectonic folds and unconformities indicate that the Aguero fan formed as the result of several phases of sedimentation which were primarily controlled by periods of tectonic activity and quiescence. The syntectonic unconformities and growth folds in the fan deposits provide a detailed record of the evolution of a fan adjacent to an active thrust front. Using a computer program to simulate sedimentation and deformation of an alluvial fan it is possible to constrain rates of both sedimentary and tectonic processes by modeling the evolution of the fan body. A facies model for the fan phases indicates that the facies change from proximal (coarse-grained, amalgamated) to distal (finger grained, stacked fining up cycles) in less than 1 km across a fan of radius estimated to be about 2 km.

  3. Responses of Riparian Cottonwoods to Alluvial Water Table Declines.

    PubMed

    SCOTT; SHAFROTH; AUBLE

    1999-04-01

    / Human demands for surface and shallow alluvial groundwater have contributed to the loss, fragmentation, and simplification of riparian ecosystems. Populus species typically dominate riparian ecosystems throughout arid and semiarid regions of North American and efforts to minimize loss of riparian Populus requires an integrated understanding of the role of surface and groundwater dynamics in the establishment of new, and maintenance of existing, stands. In a controlled, whole-stand field experiment, we quantified responses of Populus morphology, growth, and mortality to water stress resulting from sustained water table decline following in-channel sand mining along an ephemeral sandbed stream in eastern Colorado, USA. We measured live crown volume, radial stem growth, annual branch increment, and mortality of 689 live Populus deltoides subsp. monilifera stems over four years in conjunction with localized water table declines. Measurements began one year prior to mining and included trees in both affected and unaffected areas. Populus demonstrated a threshold response to water table declines in medium alluvial sands; sustained declines >/=1 m produced leaf desiccation and branch dieback within three weeks and significant declines in live crown volume, stem growth, and 88% mortality over a three-year period. Declines in live crown volume proved to be a significant leading indicator of mortality in the following year. A logistic regression of tree survival probability against the prior year's live crown volume was significant (-2 log likelihood = 270, chi2 with 1 df = 232, P < 0.0001) and trees with absolute declines in live crown volume of >/=30 during one year had survival probabilities <0.5 in the following year. In contrast, more gradual water table declines of thick similar0.5 m had no measurable effect on mortality, stem growth, or live crown volume and produced significant declines only in annual branch growth increments. Developing quantitative information on the timing and extent of morphological responses and mortality of Populus to the rate, depth, and duration of water table declines can assist in the design of management prescriptions to minimize impacts of alluvial groundwater depletion on existing riparian Populus forests. PMID:9950697

  4. Impacts of hydroelectric dams on alluvial riparian plant communities in Eastern Brazilian Amazonian.

    PubMed

    Ferreira, Leandro Valle; Cunha, Denise A; Chaves, Priscilla P; Matos, Darley C L; Parolin, Pia

    2013-09-01

    The major rivers of the Amazon River basin and their biota are threatened by the planned construction of large hydroelectric dams that are expected to have strong impacts on floodplain plant communities. The present study presents forest inventories from three floodplain sites colonized by alluvial riparian vegetation in the Tapajós, Xingu and Tocantins River basins in eastern Amazonian. Results indicate that tree species of the highly specialized alluvial riparian vegetation are clearly distinct among the three river basins, although they are not very distinct from each other and environmental constraints are very similar. With only 6 of 74 species occurring in all three inventories, most tree and shrub species are restricted to only one of the rivers, indicating a high degree of local distribution. Different species occupy similar environmental niches, making these fragile riparian formations highly valuable. Conservation plans must consider species complementarily when decisions are made on where to place floodplain forest conservation units to avoid the irreversible loss of unique alluvial riparian vegetation biodiversity. PMID:24068089

  5. Sedimentology and stratigraphy of Cenozoic deposits in the Ka??zman-Tuzluca Basin, northeastern Turkey

    NASA Astrophysics Data System (ADS)

    Varol, Baki; ?en, ?evket; Ayy?ld?z, Turhan; Sözeri, Koray; Karaka?, Zehra; Métais, Grégoire

    2015-06-01

    The Ka??zman-Tuzluca Basin is located in the northeastern Anatolia, to the east of the intersection point (near Karl?ova) of the major North and East Anatolian Fault systems. This intermontane basin displays a thick sequence (over 2000 m) of mostly terrestrial deposits represented by repetitive alternations of the lake and fluvial environments ranging from ?Late Eocene/Oligocene to Middle/? Late Miocene. A marine incursion only mappable in the southeastern margin of the basin deposited limestones and sandy limestones rich in marine mollusks and nummulites, in particular N. fichteli that constrain an Early Oligocene age for this marine unit (Ka?an Fm). The terrestrial basin-fill deposits show different thicknesses throughout the basin due to irregular bottom topography and tectonic configuration of the basin margins. The thickest deposits were accumulated along the different margins of the basin, which received high quantities of siliciclastics from meandering river, alluvial and coastal fans, fan delta/Gilbert-type delta and wave-worked fluvial delta. Climate changes have also driven the development of lake environments during distinct depositional periods. Siliciclastic-dominated overfilled lakes (Hal?k??lak and K?z?lkaya formations) and chemical-dominated underfilled lakes (Turabi and Tuzluca formations) were formed. They have been also classified as "Newark-type" and "Fundy-type" lakes, respectively. Fluvial systems evolved from high-energy meandering rivers deposited under humid climate (Güngören Formation) to low-energy meandering rivers resulted from arid and semiarid climates (Çincavat Formation). The transitional intervals from ephemeral river-dry mudflat (Çincavat Formation) to saline pan/lake (Tuzluca Formation) indicate wadi-sand flat-playa fluvial systems. The chronostratigraphic constrains of the entire sequence remain poor and so far solely based on vertebrate fossil assemblages. The evaporitic Tuzluca Formation would be Middle Miocene in age due to its stratigraphic position over the Çincavat Formation.

  6. Geomorphological evidence of neotectonic deformation in the Carnarvon Basin, Western Australia

    NASA Astrophysics Data System (ADS)

    Whitney, Beau B.; Hengesh, James V.

    2015-01-01

    This study examines channel-scale morphodynamics of ephemeral streams in the onshore Carnarvon basin in arid west-central Western Australia. The rivers in this region have low gradients, the landscape has low relief, and the rates of climatically and tectonically driven geomorphic processes also are low. As a result, the rivers in the Carnarvon alluvial plain are highly sensitive to minor perturbations in base level, channel slope, and fluvial energy. We use channel planform adjustments, stream gradient changes, and floodplain profiles across multiple ephemeral streams within a variety of catchments and flow regimes to determine if tectonically driven land level changes are affecting channel form and fluvial processes. Growth of individual fold segments is shown to have altered stream and floodplain gradients and triggered repeated avulsions at structurally controlled nodes. Aligned perturbations in channel form across multiple channel-fold intersections provide systematic geomorphic evidence for the location and orientation of neotectonic structures in the region. These features occur as a belt of low relief anticlines in the Carnarvon alluvial plain.

  7. Aridity in Vojvodina, Serbia

    NASA Astrophysics Data System (ADS)

    Hrnjak, Ivana; Luki?, Tin; Gavrilov, Milivoj B.; Markovi?, Slobodan B.; Unkaševi?, Miroslava; Toši?, Ivana

    2014-01-01

    For investigating aridity in Vojvodina, two parameters were used: the De Martonne aridity index and the Pinna combinative index. These indices were chosen as the most suitable for the analysis of climate in Vojvodina (a region in northern part of Serbia). Also, these indices were calculated from data obtained from 10 meteorological stations for the period from 1949 to 2006. The spatial distribution of the annual and seasonal De Martonne and the Pinna combinative indices as well as the mean monthly values of the De Martonne index and aridity trends of these indices are presented. There were two, four, and five types of climate on a yearly, seasonal, and monthly basis in Vojvodina, according to the De Martonne climate classification which consists of a total of seven types. In addition, semi-humid and humid climate types were represented in the region, on a yearly basis. The winter season was dominated by wetter types of climate, while the summer season was characterized by drier ones. During the spring and autumn seasons, there were types of climate which range between both aforementioned types. Two out of three climate types, which can be identified using the Pinna combinative index, were registered in Vojvodina region. The most dominant climate type was the semidry Mediterranean with formal Mediterranean vegetation, while the humid type was only identified in one small part of southwestern Vojvodina. The calculated values of both aridity indices showed that there were no annual trends. Therefore, it can be considered that there were no recent aridity changes during the observed period. For paleoclimate, the general story is more complex. The lack of aridity trends in the recent period from 1949 to 2006 supports the fact that Vojvodina has very well preserved loess-palaeosol sequences from the Middle and Late Pleistocene, which indicates that crucial point for their preservation was caused by the weak aridity variability in the region.

  8. The paradox of large alluvial rivers (Invited)

    NASA Astrophysics Data System (ADS)

    Latrubesse, E. M.

    2010-12-01

    Large alluvial rivers exhibit large floodplains, very gentle slopes, a good selection of bed materials (generally sand), low specific stream power, and could represent the ultimate examples of “dynamic equilibrium” in fluvial systems. However, equilibrium can be discussed at different temporal scales. Base level changes by tectonic or climatic effects, modifications in sediment and water supply or different kinds of human impacts are the traditional causes that could trigger “disequilibrium” and changes in the longitudinal profile. Simultaneously, adjustments of longitudinal profiles were thought to be evolving from downstream to upstream by several processes, being the most common receding erosion. Some authors,have demonstrated that when changes in base level happen, a variety of adjustments can be reached in the lower course in function of the available sediment and water discharge, slopes articulations between the fluvial reach and the continental shelve, among others, and that the adjustments can be transferred upstream significantly in small rivers but not far upstream along large fluvial systems. When analyzing the Quaternary fluvial belts of large rivers in the millennium scale, paleohydrological changes and modifications in floodplain constructional processes or erosion, are associated normally to late Quaternary climatic changes. The study of several of the largest rivers demonstrates that climatic changes and fluvial responses are not always working totally in phase and those direct cause-consequences relations are not a rule. This paper describes floodplain evolution and the lagged geomorphic responses of some large river system to recent climatic changes. Information from some of the largest rivers of the world such as the Amazon, Parana, several tributaries of the Amazon (Negro, Xingú, Tapajos) as well as some large Siberian Rivers was used. Since the last deglaciation, these large fluvial systems have not had enough time to reach equilibrium conditions along whole the river and present several stages of “incomplete floodplains”. Furthermore, minor climatic changes during the Holocene have possibly also affected their fluvial style, producing additional and partial adjustments. A main concept presented here is that large rivers achieved equilibrium conditions mainly from upstream to downstream by partially filling up their valleys and local sedimentary basins/sediment sinks (e.g. wide valleys, flood basins and permanent water saturated floodplains, tectonic sunken blocks, among others) with a variety of morpho-sedimentological processes, and transferring equilibrium conditions from upstream to downstream. When the “available space” (sedimentary sink) becomes as full of sediments as possible, the rivers adjust on a more efficient corridor of channels in quasi-equilibrium conditions. Valley infilling processes progress downstream as a prograding system on areas of the channel-floodplain system that have not yet reached quasi-equilibrium conditions Because most results in the literature are focused on small to medium size rivers, these results intend to open a new discussion about floodplain mechanisms of construction, demystifying some traditional concepts relating floodplains and equilibrium, and climatic changes and river responses in large rivers.

  9. Extremely arid soils of the Ili Depression in Kazakhstan

    NASA Astrophysics Data System (ADS)

    Lebedeva, M. P.; Gerasimova, M. I.; Golovanov, D. L.; Yamnova, I. A.

    2015-01-01

    On the basis of macro- and micromorphological and analytical studies of extremely arid soils of the Ili Depression in Kazakhstan, a comparative analysis of pedogenetic processes shaping these soils on piedmont plains of different ages and heights is performed. The types of soil horizons and their combinations are analyzed in the context opf modern Russian and international soil classification systems. The genesis of extremely arid soils is controlled by the climatic conditions and by their geomorphic position on alluvial fans of piedmont plains. The following processes are diagnosed in these soils: soil crusting with vesicular porosity, the development of desert pavements with rock varnish, rubification, surface salinization, and iron depletion around the pores. It is suggested that the initial factor-based name (extremely arid) of these soils can be replaced by the name vesicular-crusty soils with the corresponding AKL diagnostic horizon, which is more consistent with the principles of substantive-genetic classification systems. In order to determine the classification position of these soils in terms of the new Russian soil classification system, new diagnostic horizons—AKL and CS—have to be introduced in this system. According to the WRB classification, the studied soils belong to the group of Gypsisols; the soil with strong salinization fits the criteria of the group of Solonchaks. A qualifier [yermic] is to be added to reflect the development of desert pavement and vesicular layer under extreme arid conditions.

  10. Sediments in Semi-arid Wetlands: US Southern High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Playas are ephemeral wetlands on the semi-arid U.S. Southern High Plains that serve as runoff catchment basins and are thought to be focal points of Ogallala aquifer recharge. Sediments in playas alter biodiversity and hydroperiods. The purpose of this study was to evaluate the effects of outerbas...

  11. Morphodynamic equilibrium of alluvial estuaries

    NASA Astrophysics Data System (ADS)

    Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni

    2014-05-01

    The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final equilibrium state is reached through an erosional wave, which leads to bed degradation of the upstream 'fluvial reach'. For a given river discharge, the length of the tidal reach increases quite rapidly with tidal amplitude, up to some threshold value of the tidal amplitude above which the length of the estuary becomes comparable with the length of the tidal wave. When the channel plan-form is convergent, deposition of sediments of fluvial origin in the funnel-shaped region drastically changes the equilibrium configuration. The effect of an increasing channel convergence is thus to induce bed aggradation close to the inlet. Nevertheless, tidal forcing only slightly changes the non-tidal profile. The effect of increasing tidal oscillations again leads to an increase of the bed slope at the inlet and to a general bed degradation upstream. The effects of varying sediment supply, flow discharge and river width in the upstream reach have also been investigated and play an important role. Further geomorphological implications of these results will be discussed at the meeting. References Dalrymple, R. W., and K. Choi (2007), Morphologic and facies trends through the fluvialmarine transition in tide-dominated depositional systems: A schematic framework for environmental and sequence-stratigraphic interpretation, Earth-Science Reviews, 81(3-4), 135-174, doi:10.1016/j.earscirev.2006.10.002. Seminara, G., M. Bolla Pittaluga, and N. Tambroni (2012), Morphodynamic equilibrium of tidal channels, Environmental Fluid Mechanics: Memorial Volume in Honour of Prof. Gerhard H. Jirka, 153-174

  12. Detection and Mapping of Sedimentary Features on Alluvial Fans Using High-Resolution Overhead Thermal Imaging

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Moersch, J. E.; Whisner, S.

    2008-12-01

    In this study we evaluate the utility of thermal imagery for revealing geomorphic features and evidence of sedimentary processes on the surfaces of alluvial fans. Prior studies of alluvial fans have made extensive use of visible imagery and traditional field-based mapping techniques to identify surface geomorphic features and sedimentary processes. Here we present a comparison of features mapped using thermal images acquired from the ground, a light aircraft (altitude ~5000 ft, resolution ~2 m/pixel) and ASTER satellite imagery (resolution 90 m/pixel), to a preexisting ground-based map of features on an example alluvial fan in Owens Valley, California. Thermal images from a light aircraft were acquired at several times of day to determine how the surface temperatures of the alluvial fan rise and fall throughout a diurnal cycle. We have also acquired thermal images of the same fan from the ground at 5 minute intervals over the course of a full diurnal cycle. ASTER thermal data also covers the Owens Valley, and was used to determine if this technique can be used from orbit at significantly lower resolution (90 m/pixel). In an arid climate with low vegetation cover, the temperature of a surface at any given time of day is a complex function of many parameters, including slope, azimuth, composition, degree of induration, and grain size. By analyzing the temperatures on the surface of an alluvial fan with comparable slopes, azimuth, and composition, we make estimates of the relative particle size or degree of induration. We utilize the fact that several sedimentary processes acting on the surface of alluvial fans sort particles by size. For example, both debris flow and channelized flow processes can form linear features of large and small clasts. Therefore, thermal imagery could be expected to reveal evidence of these processes at the surfaces of alluvial fans in the form of spatial patterns of surface thermal properties. Process-related sedimentary features, such as clast-rich and clast-poor debris flows, debris-flow levees, and the change in particle size at the toe of the fan are all clearly revealed in the aerial thermal images of the Dolomite Fan in Owens Valley, California. The locations of these features in the thermal imagery match the locations of the features as mapped using traditional ground-based field sedimentology techniques by Blair and McPherson (1998). All debris flows that are exposed at the fan surface are evident in the aerial thermal imagery, including those that have been heavily weathered and are difficult to observe in visible aerial or orbital imagery. ASTER satellite thermal image data does not show the same sedimentary features as our aerial thermal images, presumably due to the significantly poorer spatial resolution of the satellite data. Our aerial thermal imagery suggests that higher resolution satellite data from a future satellite experiment could be used to detect sedimentary processes on alluvial fans anywhere on Earth. High resolution thermal imagery from above can be used to provide preliminary reconnaissance of an alluvial fan, suggest what processes have most recently acted on the surface of the fan, and to prioritize sites for detailed study on the ground. Future work will expand our database of alluvial fans and the list of process-related surface features that can be identified with thermal imagery.

  13. Influence of compaction on alluvial architecture

    SciTech Connect

    Anderson, S.

    1989-03-01

    Two- and three-dimensional studies of alluvial architecture were undertaken on laterally continuous coastal exposures of the Middle Jurassic nonmarine Scalby Formation of North Yorkshire, England. Sandstones and mudstones were collected and analyzed to quantify the processes involved in compaction and to investigate the influence of differential compaction on alluvial architecture. The original geometry of alluvial deposits is distorted during burial due to the juxtaposition of sediments of different compressibilities inherent in the alluvial environment. Mudstones, having higher initial porosities, compact at a greater rate than sandstones, with the result that small faults and folds may develop within the mudstone to accommodate the different compaction rates. More importantly, differential compaction affects the flood-plain topography during sedimentation and, therefore, influences the subsequent pattern of facies distribution, most notably channel-sandstone body stacking patterns. The Scalby Formation consists of a basal, complex, multilateral sheet sandstone that passes upward into meandering stream deposits, which exhibit both inclined homolithic and heterolithic stratification. Decompaction models of the sedimentary rocks reveal the original depositional architecture before differential compaction produced the present-day geometry. The decompacted sandstone/mudstone geometry provides a more accurate estimate of mudstone channel-fill thickness and inclined homolithic and heterolithic stratification dimensions, both of which are used in estimating paleochannel dimensions.

  14. Alluvial Fan, Rocky Mountain National Park

    USGS Multimedia Gallery

    The Alluvial Fan is a fan-shaped area of disturbance in Rocky Mountain National Park. It was created on July 15, 1982, when the earthen Lawn Lake Dam above the area gave way, flooding the Park and nearby town of Estes Park with more than 200 million gallons of water. Enormous boulders were displaced...

  15. Arsenate adsorption by unsaturated alluvial sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenate adsorption as a function of solution arsenic concentration and solution pH was investigated on five alluvial sediments from the Antelope Valley, Western Mojave Desert, California. Arsenate adsorption increased with increasing solution pH, exhibited a maximum around pH 4 to 5, and then decr...

  16. Late Cenozoic evolution of the upper Amargosa River drainage system, southwestern Great Basin, Nevada and California

    SciTech Connect

    Huber, N.K.

    1988-12-31

    A major part of the upper Amargosa River drainage system is centered on Timber Mountain, a high central area within a volcanic caldera northeast of Beatty, Nevada, on the west margin of the Nevada Test Site. The basic drainage pattern in this area was established soon after caldera collapse and resurgent dome formation about 11 million years ago. The gross drainage pattern has changed little since then, although subsequent volcanic activity has temporarily blocked drainage channels. As there have been no significant changes in subbasin geometry, general tectonic stability of the region during this time is implied. A major change in alluvial regimen occurred with the end of major alluvial-fan construction within the drainage system and the beginning of fanhead erosion that formed incised washes. The size and shape of incised channels differ, but they show a similar relation to the geomorphic parameters of their respective drainage basins---including such diverse-appearing washes as the deep Fortymile Wash and the wide, shallow wash on the Amargosa River downstream from Beatty. If the subbasin drainages have not changed appreciably during the Quaternary, then the forcing mechanism for the change in alluvial regimen is most likely either climatic or tectonic. Because this change appears to have occurred at about the same time throughout the upper Amargosa River drainage system, a climatic cause is preferred; its nature and timing are still speculative, but probably was increasing aridity that reached a threshold in the middle Pleistocene. This analysis also concludes that a postulated Pleistocene drainage capture by the Fortymile Canyon drainage system did not occur and that a large Pliocene lake in the Amargosa Desert, the postulated ``Lake Amargosa``, is equivocal.

  17. Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front

    USGS Publications Warehouse

    Sohn, M.F.; Mahan, S.A.; Knott, J.R.; Bowman, D.D.

    2007-01-01

    Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

  18. Seismic responses of pipelines laid through alluvial valleys

    SciTech Connect

    Liang, J.W.; Jia, S.; Hou, Z.

    1995-12-31

    In this paper, dynamic characteristics of pipelines laid through alluvial valleys are analyzed. The scattering solution of SH-waves by a shallow circular alluvial valley is used to evaluate ground motion, and pipeline-soil interaction is considered. The results show that the alluvial valley has spectacular effects on dynamic behaviors of the pipelines, and for a narrow valley, damage will appear at two interfaces between the alluvial deposit and the riverbed, and for a wider valley, the damage will appear not only at two interfaces but also in the alluvial deposit, this depends on the valley width and the wavelength of incidence seismic waves.

  19. Spatial patterns of ecohydrologic properties on a hillslope-alluvial fan transect, central New Mexico

    USGS Publications Warehouse

    Bedford, D.R.; Small, E.E.

    2008-01-01

    Spatial patterns of soil properties are linked to patchy vegetation in arid and semi-arid landscapes. The patterns of soil properties are generally assumed to be linked to the ecohydrological functioning of patchy dryland vegetation ecosystems. We studied the effects of vegetation canopy, its spatial pattern, and landforms on soil properties affecting overland flow and infiltration in shrublands at the Sevilleta National Wildlife Refuge/LTER in central New Mexico, USA. We studied the patterns of microtopography and saturated conductivity (Ksat), and generally found it to be affected by vegetation canopy and pattern, as well as landform type. On gently sloping alluvial fans, both microtopography and Ksat are high under vegetation canopy and decay with distance from plant center. On steeper hillslope landforms, only microtopography was significantly higher under vegetation canopy, while there was no significant difference in Ksat between vegetation and interspaces. Using geostatistics, we found that the spatial pattern of soil properties was determined by the spatial pattern of vegetation. Most importantly, the effects of vegetation were present in the unvegetated interspaces 2-4 times the extent of vegetation canopy, on the order of 2-3??m. Our results have implications for the understanding the ecohydrologic function of semi-arid ecosystems as well as the parameterization of hydrologic models. ?? 2007 Elsevier B.V. All rights reserved.

  20. Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Southwestern United States

    USGS Publications Warehouse

    McKinney, Tim S.; Anning, David W.

    2009-01-01

    The Southwest Principal Aquifers study area consists of most of California and Nevada and parts of Utah, Arizona, New Mexico, and Colorado; it is about 409,000 square miles. The Basin-fill aquifers extend through about 201,000 square miles of the study area and are the primary source of water for cities and agricultural communities in basins in the arid and semiarid southwestern United States (Southwest). The demand on limited ground-water resources in areas in the southwestern United States has increased significantly. This increased demand underscores the importance of understanding factors that affect the water quality in basin-fill aquifers in the region, which are being studied through the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program. As a part of this study, spatial datasets of natural and anthropogenic factors that may affect ground-water quality of the basin-fill aquifers in the southwestern United States were developed. These data include physical characteristics of the region, such as geology, elevation, and precipitation, as well as anthropogenic factors, including population, land use, and water use. Spatial statistics for the alluvial basins in the Southwest have been calculated using the datasets. This information provides a foundation for the development of conceptual and statistical models that relate natural and anthropogenic factors to ground-water quality across the Southwest. A geographic information system (GIS) was used to determine and illustrate the spatial distribution of these basin-fill variables across the region. One hundred-meter resolution raster data layers that represent the spatial characteristics of the basins' boundaries, drainage areas, population densities, land use, and water use were developed for the entire Southwest.

  1. Evidence of late early Miocene aridification intensification in the Xining Basin caused by the northeastern Tibetan Plateau uplift

    NASA Astrophysics Data System (ADS)

    Zhang, Chunxia; Xiao, Guoqiao; Guo, Zhengtang; Wu, Haibin; Hao, Qingzhen

    2015-05-01

    Few early Miocene terrestrial climate records exist from the Asian interior and as a result the evolution of Central Asian aridification and the driving forces behind it remain unclear. Here we report sedimentary, mineralogy and geochemical proxies from an early Miocene sedimentary sequence (ca. 22.1 to 16.5 Ma) from Xining Basin on the northeastern side of the Tibetan Plateau. Multiple proxies indicate a change of sedimentary facies of a distal alluvial fan from subfluvial to subatmospheric under a dominantly arid climate coupled with a clear two-stage climate change. During ~ 22.1-19.7 Ma (Unit I), the enrichment of I/S (irregular mixed-layers of illite and smectite) content, high values of a*/L* (redness/lightness), and stronger degree of chemical weathering suggest relatively warm and humid climate conditions during a generally arid climate. During 19.7-16.5 Ma (Unit II), the increase of chlorite and dolomite content, the upward decrease of a*/L*, and weaker degree of chemical weathering than Unit I suggest gradually increasing aridity since ca. 19.7 Ma. Comprehensive comparisons among records from central western China demonstrate that the aridification since ca. 19.7 Ma is widespread in northeastern part of the Tibetan Plateau. The climate changes in inner Asia are different to that of global-scale changes, which indicates that global climate changes and the retreat of the Para-Tethys Sea possibly had little influences on this region. The episodic, but persistent tectonic uplift of the north and northeastern Tibetan Plateau during the early Miocene likely played a key role in the aridification of the Xining Basin.

  2. Fire, Holocene Climate Change, and Geomorphic Response Recorded in Alluvial Fan Sediments

    NASA Astrophysics Data System (ADS)

    Pierce, J. L.; Meyer, G. A.

    2004-12-01

    Alluvial fan stratigraphic sequences record fire history in charcoal-rich deposits and buried burned soil surfaces. Deposit characteristics provide information about the magnitude of fire-related sedimentation events and severity of associated fires, and radiocarbon-dating of charcoal establishes the timing of fires. Unlike lakes, alluvial fans are ubiquitous in mountain environments. Although alluvial-fan fire records lack the annual resolution of tree-ring records, compilation of data from many alluvial fan sites provides a statistical sample of fire timing and approximate severity that can be related to climate variations over centennial to millennial timescales. We examine alluvial fan records from xeric Pinus ponderosa-dominated forests of central Idaho, and compare them with similar records from cooler, high-elevation Pinus contorta-dominated forests of Yellowstone National Park. Identification of charcoal macrofossils from Idaho fan deposits limits inbuilt age errors in radiocarbon dating, and shows that similar forest compositions have existed over the last ca. 4000 years in the fan drainage basins. Limited data from ca. 4000-7000 yr ago suggest that Pinus ponderosa was either sparse or absent in the 4 basins represented. Large fire-related debris flows in both Idaho and Yellowstone indicate severe fires during the ca. 1050-750 cal yr BP Medieval Climatic Anomaly (MCA), which included widespread and severe western US droughts. Another such episode 2700-1600 cal yr BP is less prominent in the Idaho record. Numerous small, fire-induced sedimentation events in Idaho ca. 350-500 (Little Ice Age), 1200-1400, and 2800-3000 cal yr BP likely indicate frequent low- to mixed-severity fires, and coincide with indicators of generally cool, moist conditions in the western USA and North Atlantic, and with minimal fire activity in Yellowstone. We infer that these effectively wetter periods allow greater grass growth, fueling frequent surface fires in ponderosa forests, but limiting fires in general in the effectively wetter forests of Yellowstone. Maxima in dated small events may relate to significant droughts within these intervals, e.g. in the late AD 1500s, but widespread severe fires are not indicated. Alluvial-fan records add to data from other charcoal-based proxy records of fire that indicate the importance of centennial- to millennial-scale climate change in modulating fire activity and geomorphic response in conifer forests over the Holocene.

  3. Laboratory alluvial fans in one dimension.

    PubMed

    Guerit, L; Métivier, F; Devauchelle, O; Lajeunesse, E; Barrier, L

    2014-08-01

    When they reach a flat plain, rivers often deposit their sediment load into a cone-shaped structure called alluvial fan. We present a simplified experimental setup that reproduces, in one dimension, basic features of alluvial fans. A mixture of water and glycerol transports and deposits glass beads between two transparent panels separated by a narrow gap. As the beads, which mimic natural sediments, get deposited in this gap, they form an almost one-dimensional fan. At a moderate sediment discharge, the fan grows quasistatically and maintains its slope just above the threshold for sediment transport. The water discharge determines this critical slope. At leading order, the sediment discharge only controls the velocity at which the fan grows. A more detailed analysis reveals a slight curvature of the fan profile, which relates directly to the rate at which sediments are transported. PMID:25215729

  4. Geomorphic changes leading to natural desertification versus anthropogenic land conservation in an arid environment, the Negev Highlands, Israel

    NASA Astrophysics Data System (ADS)

    Avni, Yoav; Porat, Naomi; Plakht, Joseph; Avni, Gideon

    2006-12-01

    The Negev Highlands in southern Israel are currently under an erosive regime causing degradation of soil and vegetation; a process which has often been attributed to land mismanagement and overgrazing caused by the local Bedouin population. To estimate the anthropogenic role in the erosional processes in the Negev Highlands, two similar drainage basins were selected and studied, one undisturbed with almost no human impact and the other with intensive human modification including the establishment of Roman to Early Islamic agriculture. Field observations and luminescence dating indicate that during the Late Pleistocene glacial period (OIS 4 and 3) deposition of fluvio-loess sediments, with minor erosion cycles, occurred in the Negev Highlands. Severe erosion started during OIS 2 and continued into the Holocene. As the climate shifted during the termination of the Pleistocene to the present interglacial phase, higher rain intensity generated the incision of gullies and channels into the fine-grained alluvial sediments of the previous phase, causing extended soil erosion and reducing the natural biomass and the agricultural potential. Establishment of runoff-harvesting farms in the 3rd century interrupted the Holocene natural erosion and gully incision, and led to the redeposition of up to 3.5 m of fine alluvial loess sediments originating from Late Pleistocene loess sections. This accumulation is not related to any late-Holocene pluvial climatic phase and is solely the result of farming. We conclude that since the end of the Pleistocene a dynamic change in the soil/rock ratio related to the long-term process of adjustment of the geomorphologic system to the Holocene climate has been taking place within the drainage basins in the Negev Highlands. The fluvio-loess sediments deposited in the region during OIS 4 and 3 have been eroding since the latest Pleistocene throughout the Holocene. This process causes degradation of the biomass and agricultural potential and leads onto natural desertification of the region. The historical intervention by establishment of runoff-harvesting agriculture, which as a by-product resulted in the accumulation of redeposited loess sediments, counteracted the natural trend of soil erosion. This was in fact a land-conservation act, applied by the ancient farmers in the semi-arid regions of the Middle East deserts. This activity and its geomorphic consequences are in contrast to the well-documented land degradation trend generated by recent anthropogenic impact on marginal lands elsewhere. In any case, the human impact, either contributing to land degradation or to soil conservation, is super-imposed on the natural long-term trend leading toward desertification.

  5. Metagenomic characterization of biodiversity in the extremely arid desert soils of Kazakhstan

    NASA Astrophysics Data System (ADS)

    Kutovaya, O. V.; Lebedeva, M. P.; Tkhakakhova, A. K.; Ivanova, E. A.; Andronov, E. E.

    2015-05-01

    For the first time, the composition of microbiomes in the biological crust (AKL) horizons of extremely arid desert soils (Aridic Calcisols) developed from saline and nonsaline alluvial deposits in the Ili Depression (eastern Kazakhstan) was analyzed. To describe the diversity of microorganisms in the soil samples, a novel method of pyrosequencing (Roche/454 Life Sciences) was applied. It was shown that bacteria from the Proteobacteria, Actinobacteria, Firmicutes, Verrucomicrobia, Acidobacteria, and Bacteroidetes phyla predominate in all the samples; these are typical representatives of the microbiome of soil crusts. A distinctive feature of the extremely arid soils is the high contribution of cyanobacteria (25-30%) to the total DNA. In the soils developed from saline sediments, representatives from the Rubrobacteraceae, Streptococcaceae, and Caulobacteraceae families and from the Firmicutes phylum predominated. In the soils developed from nonsaline gypsiferous deposits, bacteria from the class of Acidobacteria, subgroup Gp3, of the Methylobacteriaceae family and the class of Subdivision 3 from the Verrucomicrobia phylum predominated.

  6. Interaction of fine sediment with alluvial streambeds

    USGS Publications Warehouse

    Jobson, H.E.; Carey, W.P.

    1989-01-01

    An alluvial streambed can have a large capacity to store fine sediments that are extracted from the flow when instream concentrations are high and it can gradually release fine sediment to the flow when the instream concentrations are low. Several types of storage mechanisms are available depending on the relative size distribution of the suspended load and bed material, as well as the flow hydraulics. -from Authors

  7. Aridity changes in the Tibetan Plateau in a warming climate

    DOE PAGESBeta

    Gao, Yanhong; Li, Xia; Leung, Lai-Yung R.; Chen, Deliang; Xu, Jianwei

    2015-03-10

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of P/PET (precipitation to potential evapotranspiration) as an aridity index to indicate changes in dryness and wetness in a given area, P/PET was calculated using observed records at 83 stations in the TP, with PET calculated using the Penman–Monteith (PM) algorithm. Spatial and temporal changes of P/PET in 1979-2011 are analyzed.more » Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter and stations in the semi-humid southeastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with precipitation, sunshine duration and diurnal temperature range changes at confidence level of 99.9% from two-tail t-test. Temporal correlations also confirm the significant correlation between aridity changes with the three variables, with precipitation being the most dominant driver of P/PET changes at interannual time scale. PET changes are insignificant but negatively correlated with P/PET in the cold season. In the warm season, however, correlation between PET changes and P/PET changes are significant at confidence level of 99.9% when the cryosphere melts near the surface. Significant correlation between wind speed changes and aridity changes occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring.« less

  8. Aridity changes in the Tibetan Plateau in a warming climate

    NASA Astrophysics Data System (ADS)

    Gao, Yanhong; Li, Xia; Leung, L. Ruby; Chen, Deliang; Xu, Jianwei

    2015-03-01

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of increasing climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of precipitation to potential evapotranspiration (P/PET) as an aridity index, we used observed meteorological records at 83 stations in the TP to calculate PET using the Penman-Monteith algorithm and the ratio. Spatial and temporal changes of P/PET in 1979-2011 were analyzed. Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter, and half of the stations in the semi-humid eastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with the change patterns of precipitation, sunshine duration and diurnal temperature range. Temporal correlations between the annual P/PET ratio and other meteorological variables confirm the significant correlation between aridity and the three variables, with precipitation being the dominant driver of P/PET changes at the interannual time scale. Annual PET are insignificantly but negatively correlated with P/PET in the cold season. In the warm season, however, the correlation between PET and P/PET is significant at the confidence level of 99.9% when the cryosphere near the surface melts. Significant correlation between annual wind speed and aridity occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring.

  9. Aridity changes in the Tibetan Plateau in a warming climate

    SciTech Connect

    Gao, Yanhong; Li, Xia; Leung, Lai-Yung R.; Chen, Deliang; Xu, Jianwei

    2015-03-10

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of P/PET (precipitation to potential evapotranspiration) as an aridity index to indicate changes in dryness and wetness in a given area, P/PET was calculated using observed records at 83 stations in the TP, with PET calculated using the Penman–Monteith (PM) algorithm. Spatial and temporal changes of P/PET in 1979-2011 are analyzed. Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter and stations in the semi-humid southeastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with precipitation, sunshine duration and diurnal temperature range changes at confidence level of 99.9% from two-tail t-test. Temporal correlations also confirm the significant correlation between aridity changes with the three variables, with precipitation being the most dominant driver of P/PET changes at interannual time scale. PET changes are insignificant but negatively correlated with P/PET in the cold season. In the warm season, however, correlation between PET changes and P/PET changes are significant at confidence level of 99.9% when the cryosphere melts near the surface. Significant correlation between wind speed changes and aridity changes occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring.

  10. Sources and controls for the mobility of arsenic in oxidizing groundwaters from loess-type sediments in arid/semi-arid dry climates - evidence from the Chaco-Pampean plain (Argentina).

    PubMed

    Nicolli, Hugo B; Bundschuh, Jochen; García, Jorge W; Falcón, Carlos M; Jean, Jiin-Shuh

    2010-11-01

    In oxidizing aquifers, arsenic (As) mobilization from sediments into groundwater is controlled by pH-dependent As desorption from and dissolution of mineral phases. If climate is dry, then the process of evaporative concentration contributes further to the total concentration of dissolved As. In this paper the principal As mobility controls under these conditions have been demonstrated for Salí River alluvial basin in NW Argentina (Tucumán Province; 7000 km(2)), which is representative for other basins or areas of the predominantly semi-arid Chaco-Pampean plain (1,000,000 km(2)) which is one of the world's largest regions affected by high As concentrations in groundwater. Detailed hydrogeochemical studies have been performed in the Salí River basin where 85 groundwater samples from shallow aquifers (42 samples), deep samples (26 samples) and artesian aquifers (17 samples) have been collected. Arsenic concentrations range from 11.4 to 1660 ?g L(-1) leaving 100% of the investigated waters above the provisional WHO guideline value of 10 ?g L(-1). A strong positive correlation among As, F, and V in shallow groundwaters was found. The correlations among those trace elements and U, B and Mo have less significance. High pH (up to 9.2) and high bicarbonate (HCO(3)) concentrations favour leaching from pyroclastic materials, including volcanic glass which is present to 20-25% in the loess-type aquifer sediments and yield higher trace element concentrations in groundwater from shallow aquifers compared to deep and artesian aquifers. The significant increase in minor and trace element concentrations and salinity in shallow aquifers is related to strong evaporation under semi-arid climatic conditions. Sorption of As and associated minor and trace elements (F, U, B, Mo and V) onto the surface of Fe-, Al- and Mn-oxides and oxi-hydroxides, restricts the mobilization of these elements into groundwater. Nevertheless, this does not hold in the case of the shallow unconfined groundwaters with high pH and high concentrations of potential competitors for adsorption sites (HCO(3), V, P, etc.). Under these geochemical conditions, desorption of the above mentioned anions and oxyanions occurs as a key process for As mobilization, resulting in an increase of minor and trace element concentrations. These geochemical processes that control the concentrations of dissolved As and other trace elements and which determine the groundwater quality especially in the shallow aquifers, are comparable to other areas with high As concentrations in groundwater of oxidizing aquifers and semi-arid or arid climate, which are found in many parts of the world, such as the western sectors of the USA, Mexico, northern Chile, Turkey, Mongolia, central and northern China, and central and northwestern Argentina. PMID:21035830

  11. Evolution of the groundwater system under the impacts of human activities in middle reaches of Heihe River Basin (Northwest China) from 1985 to 2013

    NASA Astrophysics Data System (ADS)

    Mi, Lina; Xiao, Honglang; Zhang, Jianming; Yin, Zhenliang; Shen, Yongping

    2016-01-01

    Investigation of the evolution of the groundwater system and its mechanisms is critical to the sustainable management of water in river basins. Temporal and spatial distributions and characteristics of groundwater have undergone a tremendous change with the intensity of human activities in the middle reaches of the Heihe River Basin (HRB), the second largest arid inland river basin in northwestern China. Based on groundwater observation data, hydrogeological data, meteorological data and irrigation statistical data, combined with geostatistical analyses and groundwater storage estimation, the basin-scaled evolution of the groundwater levels and storage (from 1985 to 2013) were investigated. The results showed that the unbalanced allocation of water sources and expanded cropland by policy-based human activities resulted in the over-abstraction of groundwater, which induced a general decrease in the water table and groundwater storage. The groundwater level has generally fallen from 4.92 to 11.49 m from 1985 to 2013, especially in the upper and middle parts of the alluvial fan (zone I), and reached a maximum depth of 17.41 m. The total groundwater storage decreased by 177.52 × 108 m3; zone I accounted for about 94.7 % of the total decrease. The groundwater balance was disrupted and the groundwater system was in a severe negative balance; it was noted that the groundwater/surface-water interaction was also deeply affected. It is essential to develop a rational plan for integration and management of surface water and groundwater resources in the HRB.

  12. Estimating alluvial fan surface ages using Landsat 8 multispectral imagery

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Mason, Philippa J.; Whittaker, Alexander C.; Roda Boluda, Duna C.

    2015-04-01

    Accurate exposure age models are now essential for geomorphological and stratigraphic field research, and generally depend on laboratory analyses such as radiocarbon, cosmogenic nuclide or luminescence approaches. However, these techniques cannot be deployed in situ in the field, meaning other methods are needed to produce a preliminary age model, map depositional surfaces of different ages, and select sampling sites for the types of laboratory analyses outlined above. With the widespread availability of high-resolution multispectral imagery, a promising approach is to use remotely sensed data to discriminate depositional surfaces with different ages. Here, we use new Landsat 8 Operational Land Imager (OLI) multispectral imagery to characterise the reflectance of 35 alluvial fan surfaces in the semi-arid Owens Valley, California. These surfaces have been mapped in detail in the field, have similar granitic compositions, and have well-constrained exposure ages ranging from modern to ~ 125 ka, measured using a high density of 10-Be cosmogenic nuclide samples. We identify a clear age signal recorded in the spectral properties of these surfaces. With increasing exposure age, there is a predictable redshift effect in the reflectance of the surfaces across the visible and short-wave infrared spectrum. Simple calculations, such as the brightness ratio of red/blue wavelengths, produce sensitive power law relationships with exposure age for at least 125 ka, meaning Landsat 8 imagery can be used to estimate surface exposure age remotely, at least in this calibrated dryland location. The ability to remotely sense exposure age has useful implications for field mapping, selecting suitable sampling sites for laboratory-based exposure age techniques, and correlating existing age constraints to previously un-sampled surfaces. We present the uncertainties associated with this spectral approach to exposure dating, evaluate its likely physical origins, and discuss its applicability in other locations and with other remotely sensed datasets.

  13. The application of remotely sensed data to pedologic and geomorphic mapping on alluvial fan and playa surfaces in Saline Valley, California

    NASA Technical Reports Server (NTRS)

    Miller, D. A.; Petersen, G. W.; Kahle, A. B.

    1986-01-01

    Arid and semiarid regions yield excellent opportunities for the study of pedologic and geomorphic processes. The dominance of rock and soil exposure over vegetation not only provides the ground observer with observational possibilities but also affords good opportunities for measurement by aircraft and satellite remote sensor devices. Previous studies conducted in the area of pedologic and geomorphic mapping in arid regions with remotely sensed data have utilized information obtained in the visible to near-infrared portion of the spectrum. Thermal Infrared Multispectral Scanner (TIMS) and Thematic Mapping (TM) data collected in 1984 are being used in comjunction with maps compiled during a Bureau of Land Management (BLM) soil survey to aid in a detailed mapping of alluvial fan and playa surfaces within the valley. The results from this study may yield valuable information concerning the application of thermal data and thermal/visible data combinations to the problem of dating pedologic and geomorphic features in arid regions.

  14. Development and lithogenesis of the palustrine and calcrete deposits of the Dibdibba Alluvial Fan, Kuwait

    NASA Astrophysics Data System (ADS)

    AlShuaibi, Arafat A.; Khalaf, Fikry I.

    2011-08-01

    A model is proposed for the development of the Quaternary palustrine carbonate-calcrete association, which occurs as hard crust capping low hills at a distal flood plain of Al Dibdibba alluvial fan located at southwestern Kuwait. Field occurrence, detailed petrographic investigation and geochemical analysis revealed that a single cycle of groundwater calcrete with vertical gradational maturity pattern was developed. This represents a continuous sedimentological cycle during which flood sheet conditions prevailed with intermittent periods of humid and arid conditions. Subsequently, calcitic micrite was continuously precipitated from small, shallow, local, isolated and short lived ponds fringed by freshwater marshes with abundant charophyte meadows. The latter were developed as a result of flooding scattered depressions by groundwater supersaturated with respect to calcite due to rise of groundwater table. The deposition of two facies of carbonate muds, namely; biomicrite and pelintraclasts skeletal micrites was followed by a drought phase which witnessed desiccation of the fresh water ponds and significant drop in groundwater level. A sequence of pedogenic and diagenetic processes acted on the deposited carbonate muds are manifested by: (a) desiccation cracks, (b) micrite neomorphism, (c) infilling of root burrows and some cracks by aeolian siliciclastics, (d) karstification, (e) marmorization, (f) calcretization of root burrow infill and development of pseudo-rhizocrete, (g) calcite cementation and mineral authigenesis, and (h) silcretization. These processes are responsible for the development of hard palustrine carbonate crust. At the advent of aridity, the whole system of Al Dibdibba alluvial fan was subjected to deflation. This resulted in reversing the paleotopography of the hard crusted palustrine depressions into carbonate capped domal hills.

  15. Appraisal of nuclear waste isolation in the vadose zone in arid and semiarid regions (with emphasis on the Nevada Test Site)

    SciTech Connect

    Wollenberg, H.A.; Wang, J.S.Y.; Korbin, G.

    1983-05-01

    An appraisal was made of the concept of isolating high-level radioactive waste in the vadose zone of alluvial-filled valleys and tuffaceous rocks of the Basin and Range geomorphic province. Principal attributes of these terranes are: (1) low population density, (2) low moisture influx, (3) a deep water table, (4) the presence of sorptive rocks, and (5) relative ease of construction. Concerns about heat effects of waste on unsaturated rocks of relatively low thermal conductivity are considered. Calculations show that a standard 2000-acre repository with a thermal loading of 40 kW/acre in partially saturated alluvium or tuff would experience an average temperature rise of less than 100{sup 0}C above the initial temperature. The actual maximum temperature would depend strongly on the emplacement geometry. Concerns about seismicity, volcanism, and future climatic change are also mitigated. The conclusion reached in this appraisal is that unsaturated zones in alluvium and tuff of arid regions should be investigated as comprehensively as other geologic settings considered to be potential repository sites.

  16. Turkana Grits - a Cretaceous braided alluvial system in northern Kenya

    SciTech Connect

    Handford, C.R.

    1987-05-01

    Rather spotty but excellent exposures of the Cretaceous-age Turkana Grits occur near the western shore of Lake Turkana, northern Kenya. These very coarse to pebbly arkosic sandstones and sandy conglomerates were derived from and rest unconformably upon Precambrian metamorphic basement; they are overlain by late Tertiary basaltic flows that comprise much of the volcanics in the East African Rift Zone. The formation ranges up to 2000 ft thick in the Laburr Range. Several outcrops contain sauropod, crocodile, and tortoise remains as well as abundant trunks of petrified wood (Dryoxylon). Five major facies make up the Turkana Grits and record a major episode of continental fluvial deposition in basins flanked by Precambrian basement. Facies 1 is crudely stratified, cobble and boulder conglomerate (clast-supported); Facies 2 is crudely stratified pebble-cobble conglomerate and pebbly sandstone; Facies 3 is trough cross-bedded, very coarse sandstones containing fossils wood and vertebrate remains; Facies 4 is crudely stratified to massive sandstones with ironstone nodules; and Facies 5 is red, purple, and gray mudstone and mud shale with carbonate nodules. Facies 1 through 3 record deposition in proximal to medial braided-stream channel, longitudinal bar and dune complexes. Facies 4 is a lowland, hydromorphic paleosol, and Facies 5 represents overbank and abandoned channel-fill sedimentation in an alluvial plain.

  17. Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah

    USGS Publications Warehouse

    Reheis, M.C.; Reynolds, R.L.; Goldstein, H.; Roberts, H.M.; Yount, J.C.; Axford, Y.; Cummings, L.S.; Shearin, N.

    2005-01-01

    In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding to the peak of summer monsoon influence, during which soils formed relatively quickly by infiltration of eolian silt and clay, and trees and grasses were more abundant. (4) A drier period between ca. 8.5 and 6 ka during which sheetwash deposits accumulated and more desertlike vegetation was dominant; some dunes were reactivated at ca. 8 ka. (5) Episodic eolian and fluvial deposition during a wetter, cooler period that began at ca. 6 ka and ended by ca. 3-2 ka, followed by a shift to drier modern conditions; localized mobilization of dune sand has persisted to the present. These interpretations are similar to those of studies at the Chaco dune field, New Mexico, and the Tusayan dune field, Arizona, and are consistent with paleoclimate interpretations of pollen and packrat middens in the region. A period of rapid deposition and infiltration of eolian dust derived from distant igneous source terranes occurred between ca. 12 and 8 ka. Before ca. 17 ka, and apparently back to at least 45 ka, paleosols contain little or no such infiltrated dust. After ca. 8 ka, either the supply of dust was reduced or the more arid climate inhibited translocation of dust into the soils. ?? 2005 Geological Society of America.

  18. Dynamic Modeling of Meandering Alluvial Channels

    NASA Astrophysics Data System (ADS)

    Lan, Yongqiang

    1990-01-01

    The migration of meandering alluvial channels is investigated theoretically, numerically, and experimentally. An equation for the rate of bank erosion is derived from a two-dimensional continuity equation for sediment transport linked with the depth-averaged dynamic flow equations. A simple one-dimensional theoretical analysis of meander migration leads to a relationship between the migration rate and the relative channel curvature and sediment properties. The simple model appropriately simulates the pattern and rate of meander expansion and migrations of the White River, Indiana and the East Nishnabotna River, Iowa. Application of the one-dimensional model to sine -generated alluvial channels indicates that meander migration reaches its maximum when the relative radius of curvature reaches about 4.8, or when the sinuosity of meander approaches 1.3. A two-dimensional numerical model, DYNAMIC, which predicts both lateral and longitudinal migration of alluvial channels is then developed, based on a system of quasi -steady depth-averaged flow dynamic equations, a sediment continuity equation, and a bank erosion equation. A linear analysis of the two-dimensional model leads to a convolutional relation between the rate of meander migration and flow and sediment properties. In the two-dimensional numerical analysis, a numerical algorithm called FLOWSOL is developed to solve the flow dynamic equations. The flow algorithm is then linked to the sediment continuity equation and bank erosion equation to simulate bed deformation and bank erosion. The developed two-dimensional model is applied to calculate the velocity profiles in Rozovskii's experiments and the bed deformation and shear stress in Hooke's experiments. Good agreement is obtained between the calculated and measured velocities, shear stresses and bed profiles in all experiments. Small scaled meandering rivers are developed successfully on a floodplain with or without cohesive materials (about 3%) in a wide recirculating flume. The lateral migration of miniature rivers under relatively constant flow discharge is documented, analyzed, and compared with simulation results by the two-dimensional numerical model.

  19. The volcano-sedimentary evolution of a post-Variscan intramontane basin in the Swiss Alps (Glarus Verrucano) as revealed by zircon U-Pb age dating and Hf isotope geochemistry

    NASA Astrophysics Data System (ADS)

    Letsch, Dominik; Winkler, Wilfried; von Quadt, Albrecht; Gallhofer, Daniela

    2015-01-01

    The Late Palaeozoic Glarus Verrucano basin (GVB, Glarus Alps, eastern Switzerland) formed as an intramontane graben in the aftermath of the Variscan orogeny. Its fill, the Glarus Verrucano, consists of immature alluvial fan and playa lake deposits with intercalated bimodal volcanics (basalts and rhyolites). Despite its importance for local and regional geology, no modern sedimentologic or stratigraphic studies on the GVB exist. By means of sedimentologic and geochronologic studies, we reconstruct the volcano-sedimentary evolution of the GVB: it developed at the Carboniferous/Permian boundary and experienced a first (bimodal) volcanic phase around 285 Ma. For the same time, indications for temporarily humid climate in the otherwise rather arid Early Permian are demonstrated (e.g. pyrite-bearing sandstones). During the Middle and Early Late Permian, increasing aridity is indicated by playa deposits, fanglomerates and subaerial ignimbrites, which mark a second (silicic) volcanic phase at 268 Ma. The detrital zircon age spectra are dominated by Late Variscan ages and thus demonstrate that older sedimentary and metamorphic rocks once forming the Variscan nappe edifice were already mostly eroded at that time. Finally, some larger-scale speculations are given which could indicate a causal connection between the widespread tectono-magmatic Mid-Permian Episode and the local development of the Glarus Verrucano basin.

  20. CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.

    USGS Publications Warehouse

    Simon, Andrew; Hupp, Cliff R.

    1987-01-01

    This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

  1. Controls on alluvial fan long-profiles

    USGS Publications Warehouse

    Stock, J.D.; Schmidt, K.M.; Miller, D.M.

    2008-01-01

    Water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans. On alluvial fans where water transport of gravel predominates, channel slopes tend to decrease downfan from ???0.10-0.04 to ???0.01 across wide ranges of climate and tectonism. Some have argued that this pattern reflects grain-size fining downfan such that higher threshold slopes are required just to entrain coarser particles in the waters of the upper fan, whereas lower slopes are required to entrain finer grains downfan (threshold hypothesis). An older hypothesis is that slope is adjusted to transport the supplied sediment load, which decreases downfan as deposition occurs (transport hypothesis). We have begun to test these hypotheses for alluvial fan long-profiles using detailed hydraulic and particle-size data in sediment transport models. On four alluvial fans in the western U.S., we find that channel hydraulic radiiare largely 0.5-0.9 m at fan heads, decreasing to 0.1-0.2 m at distal margins. We find that median gravel diameter does not change systematically along the upper 60%-80% of active fan channels as slope declines, so downstream gravel fining cannot explain most of the observed channel slope reduction. However, as slope declines, channel-bed sand cover increases systematically downfan from areal fractions of <20% above fan heads to distal fan values in excess of 70%. As a result, entrainment thresholds for bed material might decrease systematically downfan, leading to lower slopes. However, current models of this effect alone tend to underpredict downfan slope changes. This is likely due to off-channel gravel deposition. Calculations that match observed fan long-profiles require an exponential decline in gravel transport rate, so that on some fans approximately half of the load must be deposited off channel every -0.20-1.4 km downfan. This leads us to hypothesize that some alluvial fan long-proffies are statements about the rate of overbank deposition of coarse particles downfan, a process for which there is currently no mechanistic theory. ?? 2007 Geological Society of America.

  2. High resolution sequence stratigraphy and reservoir architecture of proximal alluvial deposits: The Buntsandstein facies of central Spain

    SciTech Connect

    Oliver, L.; Desaubliaux, G.; Verdier, F.

    1995-08-01

    The Buntsandstein facies outcrops along a 12 km long, 150 m thick cuesta near Ayllon (Central Spain). The outcrop study is based on vertical sedimentological sections and continuous photo paneling, and demonstrates the presence of two depositional systems: an alluvial fan system in the lower half of the outcrop, and a straight and braided river system in the upper part of the outcrop. This overall evolution is probably related to base-level fall to base-level rise cycle, in which the reservoir architecture is linked to genetic units stacking pattern: during the base-level fall, the alluvial fan is prograding over sand flat and sandy alluvial plain deposits. Coarse and pebbly proximal sandsheets are interbedded with finer reddish distal deposits. Reservoirs units are laterally continuous, but silty alluvial plain deposits constitute vertical permeability barriers, during base-level stillstand, erosive channels and sandsheets are vertically amalgamated. Reservoirs units are laterally continuous and vertically connected, during the base-level rise, alluvial fan deposits are overlapped by straight river deposits. Reservoirs units are laterally connected but silty argillaceous alluvial plain horizons are preserved, at the end of the base-level rise, braided and straight river deposits are amalgamated. Fully connected, these reservoirs units have a very large lateral extension. A lithofacies database is compiled on this outcrop, and variograms, horizontal and vertical proportion curves are completed. Each stage of the base-level cycle is then quantitatively characterized by a specific heterogeneity pattern. The outcrop study will improve the prediction of reservoir extension and architecture in subsurface gas storage of the Paris basin.

  3. Ground Penetrating Radar Imaging of the Emigrant Peak Fault Zone and Alluvial Fan

    NASA Astrophysics Data System (ADS)

    Christie, M. W.; Tsoflias, G. P.

    2006-12-01

    Near-surface geophysical studies at the University of Kansas are investigating active faulting in the Eastern California Shear Zone. The Emigrant Peak Fault, in Fish Lake Valley, Nevada, is a normal fault that aids in the transfer of right-lateral deformation associated with the Furnace Creek/Fish Lake/Death Valley fault system of the Walker Lane Belt/Eastern California Shear Zone. During the spring and summer of 2006 we collected ground penetrating radar (GPR) across the deformed alluvial fan associated with the Emigrant Peak Fault. The GPR study is conducted in conjunction with high resolution shallow seismic and geologic investigations underway to more fully characterize the fault zone. The GPR data crosses the surface expression of the Emigrant Peak Fault and it is comprised of a 50 MHz 3-D grid and 25 MHz 2-D lines. The 3-D grid covers an area of 115m X 500m at 1m trace spacing, 5m in-line spacing and intersecting cross-lines at 50, 100, 150, 250, and 450m across the in-lines. 2-D GPR lines were acquired at coincident locations with the shallow seismic data and along a 1500m regional line over the fault and alluvial fan deposits. Depth of imaging ranged between 17m for the 50 MHz data and 25m for the 25 MHz data. GPR imaging aids in the characterization of the fault zone structurally as well as characterizing alluvial fan stratigraphy. Data shows stratigraphic reflectors on a 1m scale. Reflector geometries are quite complex, showing continuous coherent events, as well as areas that are less coherent which appear to signal a change to more boulder/cobble-rich deposition, a common characteristic in debris-flow dominated alluvial fans. The reflectors are also heavily influenced by the structural components that are imaged. The GPR shows a number of west-dipping faults that seem to migrate towards the basin. The faults are not imaged merely as interrupted reflectors, but the fault surfaces are actually imaged. Stratigraphic reflectors truncate at the faults in many instances. Some of the reflectors do not truncate, but instead roll-over into steeply dipping reflectors. The GPR data shows that not only is it useful for determining the near-surface stratigraphy of alluvial fans, but is very useful in determining the shallow structures associated with normal fault deformation in the alluvial fan as well as imaging the fault surface.

  4. Sedimentology and palaeontology of the Upper Jurassic Puesto Almada Member (Cañadón Asfalto Formation, Fossati sub-basin), Patagonia Argentina: Palaeoenvironmental and climatic significance

    NASA Astrophysics Data System (ADS)

    Cabaleri, Nora G.; Benavente, Cecilia A.; Monferran, Mateo D.; Narváez, Paula L.; Volkheimer, Wolfgang; Gallego, Oscar F.; Do Campo, Margarita D.

    2013-10-01

    Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine-palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine-Palustrine-pedogenic facies association with a 'conchostracan'-ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, and yielding 'conchostracans', body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the source of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding 'conchostracans', insect ichnofossils, and a palynoflora mainly consisting of planktonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.

  5. Geomorphology, internal structure and evolution of alluvial fans at Motozintla, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Sánchez-Núñez, J. M.; Macías, J. L.; Saucedo, Ricardo; Zamorano, J. J.; Novelo, David; Mendoza, M. E.; Torres-Hernández, J. R.

    2015-02-01

    Alluvial fans and terraces develop in diverse regions responding to different tectonic and climatic conditions. The Motozintla basin is located in the State of Chiapas, southern Mexico and has an E-W orientation following the trace of the left-lateral Polochic Fault. The evolution of the Motozintla basin and the alluvial plain is related to several factors, such as fault movement, intense erosion by hydrometeorological events, and anthropogenic activity. This study presents the geomorphology of the alluvial plain that between the villages of Motozintla and Mazapa de Juárez exposes 31 alluvial fans, 5 hanging terraces and 13 ramps. Fourteen of these alluvial fans have been truncated by the Polochic fault, exposing maximum uplifts of ~ 12 m. The internal structure of truncated fans consists of single massive beds (monolithologic fans) or stacked beds (polygenetic fans). The fans' stratigraphy is made of debris flow deposits separated by paleosols and minor hyperconcentrated flows, fluviatile beds, and pyroclastic fall deposits. The reconstruction of the stratigraphy assisted by radiocarbon geochronology suggests that these fans have been active since late Pleistocene (25 ka) to the present. This record suggests that at least 10 events have been recorded at the fan interior during the past ~ 1840 years. One of these events at 355 ± 65 14C yrs. BP (cal yrs. AD 1438 to 1652) can be correlated across the fans and is likely associated with an extreme hydrometeorologic event. The presence of a 165 ± 60 14C yrs. BP (cal yrs. AD 1652-1949) debris flow deposit within the fans suggests that movement along the Polochic fault formed the fans' scarp afterwards. In fact, a historic earthquake along the fault occurred east of Motozintla on July 22, 1816 with a Mw of 7.5-7.75. Recent catastrophic floods have affected Motozintla in 1998 and 2005 induced by extreme hydrometeorological events and anthropogenic factors. Therefore, scenarios for Motozintla involved several types of mass movement processes that pose a serious hazard and threat to the inhabitants of the region.

  6. Late Cretaceous to Mid-Tertiary Basin Evolution in the Central Tibetan Plateau: Changing Environments in Response to Tectonic Partitioning, Aridification, and Regional Elevation Gain

    NASA Astrophysics Data System (ADS)

    Decelles, P. G.; Kapp, P.

    2006-12-01

    Located in the Bangong-Nujiang suture (BNS) between the Lhasa and Qiangtang terranes of central Tibet, the Nima basin records Cretaceous through Late Miocene sediment accumulation during a period of drastically changing paleogeography, paleoclimate, and paleoelevation. The BNS formed during Latest Jurassic-Early Cretaceous time as the Lhasa terrane collided with the Qiangtang terrane. During Early to mid-Cretaceous time the region was located at or below sea level. By Aptian time (115 Ma), Nima basin was above sea level and strongly influenced by local volcanic activity and crustal shortening in the reactivated BNS zone. In the southern Nima basin, a roughly 50 Myr (Late Cretaceous through Paleocene) depositional hiatus correlates with significant crustal shortening and ensuing voluminous ignimbrite eruptions in the Lhasa terrane. In the northern Nima basin, deposition continued during latest Cretaceous time, recording arid paleoclimate in evaporitic lacustrine and eolian dunefield deposits. By Oligocene time the Nima basin comprised two depocenters accumulating coarse-grained alluvial, fluvial, lacustrine (evaporitic) and fan-delta deposits in close association with reactivated thrusts in the BNS zone. Stable carbon and oxygen isotopic data indicate that climate was arid and regional paleoelevation during the Late Oligocene was about 4.7 km, as it is today. Overall the Nima basin depositional record, combined with structural and geochronological studies, demonstrates that the BNS was reactivated during mid-Cretaceous and mid-Tertiary time, that the intervening 50 Myr interval was a time of regional upper crustal shortening in the Lhasa terrane followed by widespread ignimbrite eruptions, and that arid paleoclimate and high paleoelevation were established by Late Cretaceous and Late Oligocene time, respectively. Within the context of other data sets from the Lhasa terrane, the Nima record is consistent with low-angle subduction of Neotethyan oceanic lithosphere during Early Cretaceous time, followed by shortening within the Gangdese retroarc and northern Lhasa terrane thrust belts during mid- Cretaceous to early Tertiary time (105 to 50 Ma), accompanied, but also outlasted, by lithospheric delamination/dripping and regional magmatic flare-up during latest Cretaceous through Eocene time, followed by underthrusting of Indian lower crust and lithosphere as far north as the BNS during Late Oligocene time.

  7. Macro-roughness model of bedrock-alluvial river morphodynamics

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Parker, G.; Stark, C. P.; Inoue, T.; Viparelli, E.; Fu, X.; Izumi, N.

    2015-02-01

    The 1-D saltation-abrasion model of channel bedrock incision of Sklar and Dietrich (2004), in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise to unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation that specifically tracks the spatiotemporal variation in both bedload transport and alluvial thickness. It does so by relating the bedrock cover fraction to the ratio of alluvium thickness to bedrock macro-roughness, rather than to the ratio of bedload supply rate to capacity bedload transport. The new formulation (MRSAA) predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances, and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection-diffusion of a sediment pulse over an alluvial bed. A solution for alluvial-incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, thus blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial-bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A tectonically more complex case of rock uplift subject to a localized zone of subsidence (graben) yields a steady-state solution that is not attainable with the original saltation-abrasion model. A solution for the case of bedrock-alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressively buried not far below the alluvium. Because the model tracks the spatiotemporal variation in both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial-bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.

  8. Macro-roughness model of bedrock-alluvial river morphodynamics

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Parker, G.; Stark, C. P.; Inoue, T.; Viparelli, E.; Fu, X.; Izumi, N.

    2014-05-01

    The 1-D saltation-abrasion model of channel bedrock incision of Sklar and Dietrich, in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation which specifically tracks the spatiotemporal variation of both bedload transport and alluvial thickness. It does so by relating the cover fraction not to a ratio of bedload supply rate to capacity bedload transport, but rather to the ratio of alluvium thickness to a macro-roughness characterizing the bedrock surface. The new formulation predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection-diffusion of a sediment pulse over an alluvial bed. A solution for alluvial-incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, so blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial-bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A solution for the case of a zone of rock subsidence (graben) bounded upstream and downstream by zones of rock uplift (horsts) yields a steady-state solution that is unattainable with the original saltation-abrasion model. A solution for the case of bedrock-alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressive buried not far below the alluvium. Because the model tracks the spatiotemporal variation of both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial-bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.

  9. Fire, climate, and alluvial system dynamics: A Holocene record from Yellowstone National Park

    SciTech Connect

    Meyer, G.A. . Dept. of Geology); Wells, S.G. . Dept. of Earth Sciences); Jull, A.J. . NSF-Arizona Accelerator Facility For Isotope Dating)

    1992-01-01

    Many large debris-flow, hyperconcentrated-flow, and flood-streamflow sediment transport events have been produced in steep basins that were burned in the 1988 fires in northeaster Yellowstone National Park. The charcoal- and fines-rich character of fire-related debris-flow deposits and the abundance of similar facies in Holocene fan sections have allowed them to construct a [sup 14]C-dated chronology of fire-related sedimentation in the Soda Butte and Slough Creek drainages for the last 3500 years. Major periods of fire-related alluvial fan aggradation are interpreted as drought-dominated with the support of local paleoenvironmental data and statistical analyses of historical climate-fire relations; however, some fire-related events may occur due to high climatic variability and severe short-term drought within generally moist intervals. The last major episode of fire-related debris-flow activity encompasses the Medieval Warm Period of 900--1300 AD and peaks ca. 1150 AD; a prior episode culminates ca. 350--100 BC. Wetter periods contain minimal fire-related fan sedimentation; however, floodplain broadening and aggradation occurs along axial streams. Higher average snowmelt runoff discharges are probably involved, such that the dominant alluvial activity shifts to removal of sediment from alluvial fan storage and transport to downstream floodplains. The Little Ice Age (ca. 1300--1900 AD) contains minimal fire-related debris0flow activity and is associated with floodplain aggradation of the T4 terrace, and independent evidence suggests substantially wetter conditions during T3 aggradation ca. 350--650 AD. Thus, small-scale climate changes of the late Holocene effectively control the dominant mode of alluvial activity.

  10. Modelling the response of an alluvial aquifer to anthropogenic and recharge stresses in the United States Southern Great Plains

    NASA Astrophysics Data System (ADS)

    Zume, Joseph T.; Tarhule, Aondover A.

    2011-08-01

    This paper uses Visual MODFLOW to simulate potential impacts of anthropogenic pumping and recharge variability on an alluvial aquifer in semi-arid northwestern Oklahoma. Groundwater withdrawal from the aquifer is projected to increase by more than 50% (relative to 1990) by the year 2050. In contrast, climate projections indicate declining regional precipitation over the next several decades, creating a potential problem of demand and supply. The following scenarios were simulated: (1) projected groundwater withdrawal, (2) a severe drought, (3) a prolonged wet period, and (4) a human adjustment scenario, which assumes future improvements in water conservation measures. Results indicate that the combined impacts of anthropogenic pumping and droughts would create drawdown of greater than 12 m in the aquifer. Spatially, however, areas of severe drawdown will be localized around large-capacity well clusters. The worst impacts of both pumping and droughts will be on stream-aquifer interaction. For example, the projected aquifer pumpage would lead to a total streamflow loss of 40%, creating losing stream system regionally. Similarly, a severe drought would lead to a total streamflow loss of >80%. A post-audit of the model was also carried out to evaluate model performance. By simulating various stress scenarios on the alluvial aquifer, this study provides important information for evaluating management options for alluvial aquifers.

  11. Fertilizers mobilization in alluvial aquifer: laboratory experiments

    NASA Astrophysics Data System (ADS)

    Mastrocicco, M.; Colombani, N.; Palpacelli, S.

    2009-02-01

    In alluvial plains, intensive farming with conspicuous use of agrochemicals, can cause land pollution and groundwater contamination. In central Po River plain, paleo-channels are important links between arable lands and the underlaying aquifer, since the latter is often confined by clay sediments that act as a barrier against contaminants migration. Therefore, paleo-channels are recharge zones of particular interest that have to be protected from pollution as they are commonly used for water supply. This paper focuses on fertilizer mobilization next to a sand pit excavated in a paleo-channel near Ferrara (Italy). The problem is approached via batch test leaking and columns elution of alluvial sediments. Results from batch experiments showed fast increase in all major cations and anions, suggesting equilibrium control of dissolution reactions, limited availability of solid phases and geochemical homogeneity of samples. In column experiments, early elution and tailing of all ions breakthrough was recorded due to preferential flow paths. For sediments investigated in this study, dispersion, dilution and chemical reactions can reduce fertilizers at concentration below drinking standards in a reasonable time frame, provided fertilizer loading is halted or, at least, reduced. Thus, the definition of a corridor along paleo-channels is recommended to preserve groundwater quality.

  12. Groundwater quality in the Northern Coast Ranges Basins, California

    USGS Publications Warehouse

    Mathany, Timothy M.; Belitz, Kenneth

    2015-01-01

    Recharge to the groundwater system is primarily from mixture of ambient sources, including direct percolation of precipitation and irrigation waters, infiltration of runoff from surrounding hills/areas, seepage from rivers and creeks, and subsurface inflow (from non-alluvial geologic units that bound the alluvial basins). The primary sources of discharge are evaporation, discharge to streams, and water pumped for municipal supply and irrigation.

  13. Simulating Fine grained Alluvial Fan Sedimentation on Mars

    NASA Astrophysics Data System (ADS)

    Morgan, A. M.; Howard, A. D.; Moore, J. M.; Beyer, R. A.

    2013-12-01

    The alluvial fans on Mars date to as late as the Hesperian Period and may be representative of the last major episode of widespread fluvial modification to the red planet's surface. These fans lie within enclosed crater basins, and are characterized by their large size (tens of km in length) and gentle gradient (less than 1-3°). The fans generally feature a network of channel distributaries floored with coarser sediment and what we have interpreted to be fine grained overbank deposits that comprise the bulk of the fan material [1]. We have developed a landform evolution model based on the approach of [2] to simulate the growth of these fans in order to answer several questions about their formation, including: (1) what are the characteristics of water discharge (flow magnitude and duration) and sediment supply (quantity and grain size); and (2) what are the associated implications for the responsible climatic environment (e.g. amount and frequency of precipitation sourcing the fans). The model combines discharge and sediment deposition with channel avulsion and abandonment, allowing for an analysis of both the micro and macro scale processes concerning fan formation. Water and sediment is routed through a distributary network that can branch, recombine, and avulse. The model simulates deposition of both coarse-grained bedload and a fine-grained suspended load material that can be deposited overbank during flood events. The model records the stratigraphy of the deposited material in terms of the relative proportions of coarse and fine-grained sediment. Using measures such as channel width, relative proportions of channel versus overbank deposited sediment, and frequency of channel branching, output is statistically compared with digital elevation models that have been produced from high-resolution CTX and HiRISE stereo pairs. Initial results suggest fans formed from hundreds of flow events over many thousands of years. Fan formation processes appear to be similar to those active in terrestrial fans in northern Chile's Atacama Desert. Additional model runs will simulate fan development under different patterns of precipitation (uniform over the fan versus an orographic pattern of greater precipitation on upper crater walls) and variations in sediment size distribution. References: [1] Morgan, A. M., Howard, A. D., Hobley, D. E. J., Moore, J. M., Dietrich, W. E., Williams, R. M. E., Burr, D. M., Grant, J. A., Wilson, S. A., and Matsubara, Y. (in review) Sedimentology and Climatic Environment of Alluvial Fans in the Martian Saheki Crater and a Comparison with Terrestrial Fans in the Atacama Desert [2] Sun, T., C. Paola, G. Parker, and P. Meakin (2002), Water Resour. Res., 38, no.8, 10.

  14. Monti Martani (umbria, Italy) Alluvial Fans: Hazards Sites and Occurrence

    NASA Astrophysics Data System (ADS)

    Taramelli, A.; Melelli, L.

    In this paper we proposed modeling and simulation approaches for testing the debris flows occurrence hypothesis. The approach is an empirically and process based, and use multiple physically-based simulations to evaluate hazard down-slope from initiation sites in alluvial fans of the Terni basin-northern area (Umbria, Italy). The northern part of the area is bounded by the M. Martani normal fault that controls the drainage network where produces a large debris piedimont deposition. The main fault scarp is cut by narrow streams that represents the dominant constructional process by three alluvial fans generations. Field-based and remote sensing observations from the area will be used to provide a sound empirical evaluation of the new landslide occurrence hypothesis. In humid, soil-mantled environments in particular, debris flow always originate in fine-scale valleys in steep, rhythmically dissected terrain. Concave planform contours define topographic swales, referred to as "hollows" in the nomenclature, that typically contain colluvial soils significantly thicker than those found on adjacent slope. Areas underlain by massive, resistant bedrock, show that the majority of debris flows originated in colluvium-filled hollows. Hollows consequently define a mappable debris flow hazard. The association of debris flow with hollows is governed by relations between sediment transport, hillslope hydrology and slope stability. Consequently, colluvial deposits in hollows are particularly susceptible to landsliding. Furthermore topographic converge also focuses subsurface runoff into hollows, so high intensity rainfall cells indicate that a lack of historic landsliding from specific hollow is by no means an indicator of future stability. The strong likelihood that the 25m resolution DEM can be used in this project means that we will have the topographic control to do more detailed modeling of hill slope hydrology to account for spatial and temporal variability in groundwater saturation on hillslopes, and the consequences for slope failure. We will use a software tools for multiflow routing of runoff given a precipitation model, a DEM, and a probabilistic model of finding pockets of colluvium on hillslopes which is demonstrated for the synthetic hillslope.

  15. Denudation rates from mass balance on alluvial fans in the chinese Tian Shan

    NASA Astrophysics Data System (ADS)

    Guerit, Laure; Barrier, Laurie; Métivier, François; Jolivet, Marc; Fu, Bihong

    2015-04-01

    Denudation is a key process for mountain ranges evolution as it is an essential parameter to study the mass transfer over the Earth surface, the evolution of reliefs, or the complex relationships between climate, erosion and landscape changes. Several methods have been develop to quantify denudation such as the estimation of paleo-sediment fluxes from mass budget. In fact, markers of erosion within drainage areas are often scarce, temporary and difficult to reach. At the outlet of mountain belts, more continuous and perennial records of deposition can be found in sedimentary basins. Sediment budget is thus a powerful approach, generally used at the scale of sedimentary basins. However, this method can also be applied on smaller sedimentary systems, such as alluvial fans. Yet, it is seldom used on these systems, and consequently, its accuracy is barely questioned. We propose to implement such a method on several alluvial fan systems in the Chinese part of the Tian Shan Range, where estimations of denudation rates have already been proposed. Based on the reconstruction of two generations of alluvial fans, we estimate the volume of sediment exported out of the drainage system of the range for the Middle- Late Pleistocene (300 000 to ~11 000 y) and for the Holocene (~11 000 y to present). From these volumes, we derive denudation rates of ~135 m/My at maximum for these two periods, in good agreement with previous mass balance studies. Despite a strong change in the morphology of the piedmont at the onset of the Holocene, denudation rate seems quite stable within the hinterland mountains. This value is quite low for such a range. Based on a comparison of denudation rates observed in other areas over the world with comparable shortening or precipitation rates, we suggest that the low denudation rate observed in the chinese Tian Shan is related to the limited amount of precipitation.

  16. Mapping Quaternary Alluvial Fans in the Southwestern United States based on Multi-Parameter Surface Roughness of LiDAR Topographic Data

    NASA Astrophysics Data System (ADS)

    Regmi, N. R.; McDonald, E.; Bacon, S. N.

    2012-12-01

    Quaternary alluvial fans, common landforms in hyper- to semi-arid regions, have diverse surface morphology, desert varnish accumulation, clasts rubification, desert pavement formation, soil development, and soil stratigraphy. Their age and surface topographic expression vary greatly within a single fan between adjacent fans. Numerous studies have demonstrated that the surface expression and morphometry of alluvial fans can be used as an indicator of their relative age of deposition, but only recently has there been an effort to utilize high resolution topographic data to differentiate alluvial fans with automated and quantifiable routines We developed a quantitative model for mapping the relative age of alluvial fan surfaces based on a multi-parameter surface roughness computed from 1-meter resolution LiDAR topographic data. Roughness is defined as a function of scale of observation and the integration of slope, curvature (tangential), and aspect topographic parameters. Alluvial fan roughness values were computed across multiple observation scales (3m×3m to 150m×150m moving observation windows) based on the standard deviation (STD) of slope, curvature, and aspect. Plots of roughness value versus size of observation scale suggest that the STD of each of the three topographic parameters at 7m×7m observation window best identified the signature of surface roughness elements. Roughness maps derived from the slope, curvature, and aspect at this scale were integrated using fuzzy logic operators (fuzzy OR and fuzzy gamma). The integrated roughness map was then classified into five relative morpho-stratigraphic surface age categories (active wash to ~400 ka) and statistically compared with a similar five-fold surface age map of alluvial fans developed using traditional field surveys and aerial photo interpretation. The model correctly predicted the distribution and relative surface age of ~61% of the observed alluvial fan map. The results of the multi-parameter model imply that the first order roughness elements of alluvial fan surfaces have the average wavelength of 7m, and the roughness contributed by these elements decreases with the age of alluvial fans.

  17. Downstream changes in alluvial architecture: An exploration of controls on channel-stacking patterns

    SciTech Connect

    Heller, P.L.; Paola, C.

    1996-03-01

    Various, but related, models have been proposed to explain the architectural arrangement of channel stacking patterns in avulsion-dominated alluvial sequences. The early models published by Leeder, Allen, and Bridge (LAB) addressed the role of changes in sedimentation rate (a proxy for subsidence rate) as a control on stacking patterns. The models decouple avulsion frequency from sedimentation rates, resulting in an inverse relationship between stacking density (or interconnectedness) and sedimentation rates. A key element missing from these models is the likely dependence of avulsion frequency on local sedimentation rate within the active channel belt. The authors consider a simple model whereby avulsion takes place only when a minimum, critical, relief is developed between a channel bank and the adjacent flood plain. They provide an alternative, simple geometric model that links changes in subsidence rate to downstream rate of change in stacking pattern as seen in three dimensions within sedimentary basins. Other controls that are considered include: the geometry of subsidence; whether avulsions take place locally along a river or regionally affect the basin; whether local sedimentation rate of flow depth controls the thickness of sand bodies; and the exact relationship between avulsion frequency and sedimentation rate. The primary result of the model is that subsidence strongly influences the rate at which alluvial architecture changes in the downstream direction, but other controls dictate whether the stacking pattern becomes more dense or less dense downstream.

  18. The Jornada Basin long term ecological research program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chihuahuan Desert landscapes exemplify the ecological conditions, vulnerability, and management challenges in arid and semi-arid regions around the world. The goal of the Jornada Basin Long Term Ecological Research program (JRN LTER) established in 1982 is to understand and quantify the key factors ...

  19. Downstream hydraulic geometry of alluvial rivers

    NASA Astrophysics Data System (ADS)

    Julien, P. Y.

    2015-03-01

    This article presents a three-level approach to the analysis of downstream hydraulic geometry. First, empirical concepts based on field observations of "poised" conditions in irrigation canals are examined. Second, theoretical developments have been made possible by combining basic relationships for the description of flow and sediment transport in alluvial rivers. Third, a relatively new concept of equivalent channel widths is presented. The assumption of equilibrium may describe a perpetual state of change and adjustments. The new concepts define the trade-offs between some hydraulic geometry parameters such as width and slope. The adjustment of river widths and slope typically follows a decreasing exponential function and recent developments indicate how the adjustment time scale can be quantified. Some examples are also presented to illustrate the new concepts presented and the realm of complex river systems.

  20. Sand-flat/playa mud-flat-lacustrine cycles in Fundy rift basin (Triassic-Jurassic), Nova Scotia: implications for climatic and tectonic controls

    SciTech Connect

    Mertz, K.A. Jr.; Hubert, J.F.

    1989-03-01

    Blomidon Formation red beds comprise over 200 m-scale cycles of (1) sand-flat sandstone (distal alluvial-fan deposits) and (2) playa sandy mudstone and/or lacustrine claystones. Rift basin subsidence and local sagging along the Glooscap fault system generated sand-flat/playa mud-flat cycles by shifting loci of active fan sedimentation toward and away from the playa surface as fan lobes migrated toward topographic lows. Episodes of intense aridity are recorded in the sand-flat and playa mud-flat deposits where amalgamated sheetflood packages are characterized by pervasive evaporite mineralization (principally gypsum) controlled by subsurface evolution of a Ca-SO/sub 4/-Na-Cl brine. Aridity is further evidenced by significant disruption of sedimentary fabrics beneath evaporite crusts, deep mud cracks, eolian sandstone layers and patches, and precipitation of authigenic calcium and magnesium-rich illite/smectite and analcime. Carbon isotopic data from early formed, low-magnesium calcite cements (pre-gypsum) reflect slightly to moderately elevated subsurface salinities that accompanied initial brine evolution. During relatively wetter periods, lacustrine platy claystones accumulated in shallow, oxidizing lakes that lapped onto the sand flats. Claystone units lack evaporite minerals and textures, and many units are partially burrowed. Carbon isotopic data from calcite cements are consistently lighter than sand-flat/playa mud-flat calcites and were in equilibrium with relatively fresh subsurface pore waters.

  1. Flood susceptibility assessment in a highly urbanized alluvial fan: the case study of Sala Consilina (southern Italy)

    NASA Astrophysics Data System (ADS)

    Santangelo, N.; Santo, A.; di Crescenzo, G.; Foscari, G.; Liuzza, V.; Sciarrotta, S.; Scorpio, V.

    2011-10-01

    This paper deals with the risk assessment to alluvial fan flooding at the piedmont zone of carbonate massifs of the southern Apennines chain (southern Italy). These areas are prime spots for urban development and are generally considered to be safer than the valley floors. As a result, villages and towns have been built on alluvial fans which, during intense storms, may be affected by flooding and/or debris flow processes. The study area is located at the foothills of the Maddalena mountains, an elongated NW-SE trending ridge which bounds to the east the wide intermontane basin of Vallo di Diano. The area comprises a wide detrital talus (bajada) made up by coalescent alluvial fans, ranging in age from the Middle Pleistocene to the Holocene. Historical analysis was carried out to ascertain the state of activity of the fans and to identify and map the zones most hit by past flooding. According to the information gathered, the Sala Consilina fans would appear prone to debris flows; in the past these processes have produced extensive damage and loss of life in the urban area. The watershed basins feeding the fans have very low response times and may produce debris flow events with high magnitudes. Taking into account the historical damage, the fan surface morphology, and the present urban development (street orientation and hydraulic network), the piedmont area was zoned and various susceptibility classes were detected. These results may represent a useful tool for studies aiming at territorial hazard mapping and civil protection interventions.

  2. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Wu, B.; Zheng, Y.

    2013-12-01

    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  3. Chloride mass-balance method for estimating ground water recharge in arid areas: Examples from western Saudi Arabia

    USGS Publications Warehouse

    Bazuhair, A.S.; Wood, W.W.

    1996-01-01

    The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in time and space it appears to be, with certain assumptions, particularly well suited for and areas with large temporal and spatial variation in recharge. In general, recharge was found to be between 3 to 4% of precipitation - a range consistent with recharge rates found in other arid and semi-arid areas of the earth.

  4. Particle dynamics: The continuum of bedrock to alluvial river segments

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen

    2015-07-01

    Particle dynamics refers to production, erosion, transport, and storage of particulate material including mineral sediment and organic matter. Particle dynamics differ significantly between the end members of bedrock and alluvial river segments and between alluvial river segments with different grain-size distributions. Bedrock segments are supply limited and resistant to change, with relatively slow, linear adjustments and predominantly erosion and transport. Particle dynamics in alluvial segments, in contrast, are transport limited and dominated by storage of mineral sediment and production of organic matter. Alluvial segments are resilient to change, with relatively rapid, multidirectional adjustments and stronger internal influences because of feedbacks between particles and biota. Bedrock segments are the governors of erosion within a river network, whereas alluvial segments are the biogeochemical reactors. Fundamental research questions for both types of river segments center on particle dynamics, which limit network-scale incision in response to base level fall (bedrock segments) and habitat, biogeochemical reactions, and biomass production (alluvial segments). These characterizations illuminate how the spatial arrangement of bedrock and alluvial segments within a river network influence network-scale resistance and resilience to external changes in relative base level, climate, and human activities.

  5. Alluvial Bars of the Obed Wild and Scenic River, Tennessee

    USGS Publications Warehouse

    Wolfe, W.J.; Fitch, K.C.; Ladd, D.E.

    2007-01-01

    In 2004, the U.S. Geological Survey (USGS) and the National Park Service (NPS) initiated a reconnaissance study of alluvial bars along the Obed Wild and Scenic River (Obed WSR), in Cumberland and Morgan Counties, Tennessee. The study was partly driven by concern that trapping of sand by upstream impoundments might threaten rare, threatened, or endangered plant habitat by reducing the supply of sediment to the alluvial bars. The objectives of the study were to: (1) develop a preliminary understanding of the distribution, morphology, composition, stability, and vegetation structure of alluvial bars along the Obed WSR, and (2) determine whether evidence of human alteration of sediment dynamics in the Obed WSR warrants further, more detailed examination. This report presents the results of the reconnaissance study of alluvial bars along the Obed River, Clear Creek, and Daddys Creek in the Obed WSR. The report is based on: (1) field-reconnaissance visits by boat to 56 alluvial bars along selected reaches of the Obed River and Clear Creek; (2) analysis of aerial photographs, topographic and geologic maps, and other geographic data to assess the distribution of alluvial bars in the Obed WSR; (3) surveys of topography, surface particle size, vegetation structure, and ground cover on three selected alluvial bars; and (4) analysis of hydrologic records.

  6. Investigations on the Aridity Paradox

    NASA Astrophysics Data System (ADS)

    Donohue, R. J.; Roderick, M. L.

    2014-12-01

    How global aridity might change in the immediate future is an important question. Several recent analyses have concluded that aridity will, in general, increase over land primarily because of increasing vapour pressure deficit. Taken at face value that result is difficult to understand because a warmer world is also anticipated to be a moister world. For example, at the global scale, climate model projections are for increasing rainfall and runoff. In this presentation we investigate this seeming paradox. We find that the previous analyses have not accounted for the biological impacts of elevated CO2 and when that is incorporated, the climate model projections are for a modest reduction in meteorological and hydrologic aridity and for larger reductions in biological aridity.

  7. Design of flood protection for transportation alignments on alluvial fans

    SciTech Connect

    French, R.H.

    1991-01-01

    The method of floodplain delineation on alluvial fans developed for the national flood insurance program is modified to provide estimates of peak flood flows at transportation alignments crossing an alluvial fan. The modified methodology divides the total alignment length into drainage design segments and estimates the peak flows that drainage structures would be required to convey as a function of the length of the drainage design segment, the return period of the event, and the location of the alignment on the alluvial fan. An example of the application of the methodology is provided. 16 refs., 5 figs.

  8. Distribution and Orientation of Alluvial Fans in Martian Craters

    NASA Technical Reports Server (NTRS)

    Kraal, E. R.; Moore, J. M.; Howard, A. D.; Asphaug, E. I.

    2005-01-01

    We present the results of the complete survey of Martian alluvial fans from 0-30 S, initiated by Moore and Howard. Nineteen impact craters contain alluvial fans. They are regionally grouped into three distinct areas. We present our initial results regarding their distribution and orientation in order to understand what controls their formation. Since alluvial fans are formed by water transport of sediment, these features record wetter episodes of Martian climate. In addition, their enigmatic distribution (in regional groups and in some craters, but not similar adjacent ones) needs to be understood, to see how regional geology, topographic characteristics, and/or climate influence their formation and distribution.

  9. Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq

    NASA Astrophysics Data System (ADS)

    Heyvaert, Vanessa M. A.; Walstra, Jan; Mortier, Clément

    2014-05-01

    The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013). Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes. Here we present a reconstruction of the Late Holocene evolution of the Diyala alluvial fan (one of the main tributaries of the Tigris in Iraq), with particular attention to the relations between alluvial fan development, changes in channel pattern, the construction of irrigation networks and the rise and collapse of societies through historic times. The work largely draws on the use of remote sensing and GIS techniques for geomorphological mapping, and previously published archaeological field data (Adams 1965). By linking archaeological sites of known age with traces of ancient irrigation networks we were able to establish a chronological framework of alluvial activity of the Diyala alluvial fan. Our results demonstrate that centralized and technologically advanced societies were able to maintain a rapidly aggradading distibutary channel system, supplying water and sediment across the entire alluvial fan. As a consequence, during these periods (Parthian, Sasanian and again in modern times), significant human modification of the landscape took place. Periods of societal decline are associated with reduced human impact and the development of a single-threaded incising river system. Adams, R.M. (1965). Land behind Baghdad: A history of settlement on the Diyala plains. University of Chicago Press, Chicago, Illinois. Heyvaert, V.M.A. & Baeteman, C. (2008). A Middle to Late Holocene avulsion history of the Euphrates river: a case study from Tell ed-D-er, Iraq, Lower Mesopotamia. Quaternary Science Reviews, 27, 2401-2410. Heyvaert, V. M. A., Walstra, J., Verkinderen, P., Weerts, H. J. T. & Ooghe, B. (2012). The role of human interference on the channel shifting of the river Karkheh in the Lower Khuzestan plain (Mesopotamia, SW Iran). Quaternary International, 251, 52-63. Heyvaert, V.M.A., Walstra, J., Weerts, H.J.T. (2013). Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran. Abstractbook of the 10th International Fluvial Sedimentology Conference, July 2013,Leeds, United Kingdom. Morozova, G.S. (2005). A review of Holocene avulsions of the Tigris and Euphrates rivers and possible effects on the evolution of civilizations in lower Mesopotamia. Geoarchaeology, 20, 401-423. Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. (2010). Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran). Geodinamica Acta, 23, 267-285. Wilkinson, T.J. (2003). Archaeological Landscapes of the Near East. The University of Arizona Press, Tucson, Arizona.

  10. From source to sink in the sediment cascade of the Hei-River Basin: Implications for late Quaternary landscape dynamics in the Gobi Desert, NW China

    NASA Astrophysics Data System (ADS)

    Schimpf, Stefan; Nottebaum, Veit; Diekmann, Bernhard; Hartmann, Kai; Lehmkuhl, Frank; Wünnemann, Bernd; Zhang, Chi

    2014-05-01

    The Hei River Basin with a catchment size of ~130,000 km² is host to one of the largest continental alluvial fans in the world. The basin comprises: (1) its high-elevated river sources in the glacier and the permafrost zone of the Qilian Mountains, (2) the semi-arid foreland of the Hexi Corridor in the middle reaches and (3) the endorheic Ejina Basin (Gaxun Nur Basin) as its recent sink. The river basin is characterized by small subcatchments of hyper-arid mountain ranges of the Gobi-Tienshan and Beishan as well as of smooth and fuzzy water divides of the Hexi-Corridor and the Badain Jaran Sand Sea. Up to 300 m of Quaternary sediments establish the large Ejina Basin, with a size of 28,000 km², as an excellent archive for environmental reconstructions located at the recent intersection of westerly and monsoonal air masses. Three sediment cores (up to 230 m long) provide evidence of sedimentation dynamics over the last 250,000 years, and cover at least two terminations since OIS 6. The sediments have to be regarded as a result of the interplay between tectonic activity and climate dynamics, accompanied by a related eolian and hydrological response of the catchment. Thus, it is crucial to understand and reconstruct the sedimentary processes along the huge sediment cascades, and to identify the most important sediment sources. Here we present a provenance analysis from mineralogical fingerprints of modern sediments that have been deposited along recent pathways from the sources to the Ejina Basin. The methodical approach combines the analysis of clay minerals, bulk mineralogy, and bulk geochemistry. Furthermore, we use heavy mineral data obtained from automated particle-analysis via a computer-controlled scanning electron microscope (CCSEM) and XRD measurements. We analyzed ~200 surface samples from the whole catchment as reference material, as well as the upper 19 m of cored sediments, to gain insight into temporal changes of depositional processes and provenance. Geostatistical analyses of the compositional data reveal a clear discrimination between sediments from the Qilian Shan in the south and from local basin sediments in the north. Moreover the mineralogical fingerprints allow the differentiation of sources from intrusive rocks that are dominant in the Bei Shan mountain sub-catchment, and from greenschist-bearing metamorphic rocks, that are widespread in the Qilian Mountain catchment. Finally, we draw conclusions about the main transport processes and pathways from assumed source regions to the sink (Ejina Basin). The provenance analysis of the sediment core reveals strong changes from local (Bei Shan) to long-distant (Qilian Shan) sources. The Late Pleistocene record reveals frequently changing sediment supply between periodic high mountain runoff and local episodic runoff. We assume that these variations are related to basin internal processes (e.g. fan dynamics, tectonics) and changing environmental conditions that are linked with variations in meltwater runoff and precipitation in the upper reaches of the southern catchment. These conclusions are supported by grain size characteristics that indicate phases of predominant alluvial activity and limnic deposition around the Late Glacial to Holocene transition and enhanced pre-Holocene eolian activity.

  11. Characterization and architecture of fluvial sand bodies in a intracratonic alluvial fan

    SciTech Connect

    Martinius, A.W.; Cuevas Gozalo, M.C. )

    1993-09-01

    The fluvial deposits of the Tortola alluvial fan of late Oligocene to early Miocene were deposited in the intracratonic Loranca Basin (Spain). the fluvial facies comprise individual and amalgamated sand bodies embedded in flood-plain fines. The succession is a labyrinth-type reservoir analog. A distal and proximal fan locality have been compared. The sand bodies were characterized and quantified by means of three-dimensional (3-D) morphology and facies analysis, sandbody size statistics, permeability and gamma-ray log profiles, and geometry of permeability baffles. A classification of the sand bodies in six genetic types was established: meander-loop, low-sinuosity channel-fill, braided channel-fill, deltaic, interchannel bar, and crevasse-splay deposits. This classification is conditioned by a set og geological rules. The external geometry, internal organization, and spatial arrangement of the genetic types is determined by variation in hydrodynamic conditions, sediment supply, fan morphology, and basin subsidence. Significant differences in reservoir quality exist between the genetic types, and between the two fan localities. Analysis of the sequential development of the two localities shows that the 3-D architecture is the result of coalescing fan depositional systems: a minor fluvial fan systems from the eastern basin margin, and local minor fluvial systems. Shifting of the channels on the fan surface due to avulsion processes, differential basin subsidence, and tectonic movements influenced fan formation and hence reservoir quality.

  12. A classification of Meso-Cenozoic continental basins and their oil-gas potentials in China

    SciTech Connect

    Wu Changlin ); Xue Shuhao )

    1991-03-01

    Most of the oilfields in China are located in Mesozoic-Cenozoic continental basins. Characteristics of continental sediments are controlled by such factors as paleoclimatic zones, distance from oceans, paleogeomorphic features, and tectonic settings. Based on paleoclimatic zonation, the continental basins in China can be divided into humid, arid, and humid-arid transitional types. Furthermore, based on the distances from oceans, they can be classified into inland and onshore types, and based on regional geomorphic features, they can be classified into faulted and depressional types. According to three factors, the Mesozoic-Cenozoic continental petroliferous basins in China can be grouped under ten types as follows: (1) onshore humid faulted type such as Zhujiangkou (Pearl River Mouth; E); (2) onshore humid depressional type such as Songliao (K); (3) inland humid faulted type such as Baise (E); (4) inland humid depressional type such as Ordos (T); (5) onshore arid-humid faulted type such as Bohai Bay (E); (6) inland arid-humid faulted type such as Jiuxi (K); (7) inland arid-humid depressional type such as Junggar (E); (8) onshore arid depressional type such as Tarim (E); (9) inland arid faulted type such as Jianghan (E); and (10) inland arid depressional type such as Tsaidam (E-N). Sedimentary systems in different basins have different depositional characteristics and petroliferous potentials. Onshore basins in humid zone and arid-humid transitional zone have best petroleum prospects, and inland basins in humid and arid-humid transitional zones are second while the basins in arid zone are third.

  13. Reseach of Soil Moisture Measurement in Arid Areas by Using Ground-penetrating Radar

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Yin, X.; Zhao, Q.; Wu, Y.

    2014-12-01

    Inland river basins under an arid rain-fed environment have low and limited water content, in which soil water availability plays a key role in root growth and function and is the prime factor to limit the number and size of plant species. Compared with conventional point measurements and remote sensing method, ground-penetrating radar (GPR) provides an effective methodology for rapidly mapping continuous soil moisture at an intermediate scale, which is of significance to research the processes in arid areas, desert vegetation protection, precision water regulation and water-saving irrigation. By selecting the Urumqi River Basin for experimental observations, this study considered the typical arid landscapes and soil characteristics, and then used ground-penetrating radar to monitor soil moisture in different sites, with time domain reflectometry (TDR) and gravimetric sampling method used synchronously to validate the accuracy and suitability of GPR method.

  14. Geomorphologic flood-hazard assessment of alluvial fans and piedmonts

    USGS Publications Warehouse

    Field, J.J.; Pearthree, P.A.

    1997-01-01

    Geomorphologic studies are an excellent means of flood-hazard assessment on alluvial fans and piedmonts in the southwestern United States. Inactive, flood-free, alluvial fans display well developed soils, desert pavement, rock varnish, and tributary drainage networks. These areas are easily distinguished from flood-prone active alluvial fans on aerial photographs and in the field. The distribution of flood-prone areas associated with alluvial fans is strongly controlled by fanhead trenches dissecting the surface. Where fanhead trenches are permanent features cut in response to long-term conditions such as tectonic quiescence, flood-prone surfaces are situated down-slope from the mountain front and their positions are stable for thousands of years. Since the length and permanency of fanhead trenches can vary greatly between adjacent drainages, it is not appropriate to use regional generalizations to evaluate the distribution and stability of flood-hazard zones. Site-specific geomorphologic studies must be carried out if piedmont areas with a high risk of flooding are to be correctly identified and losses due to alluvial-fan flooding minimized. To meet the growing demand for trained professionals to complete geomorphologic maps of desert piedmonts, undergraduate and graduate geomorphology courses should adopt an instructional unit on alluvial-fan flood hazards that includes: 1) a review of geomorphologic characteristics that vary with surface age; 2) a basic mapping exercise; and 3) a discussion of the causes of fanhead trenching.

  15. Water sources accessed by arid zone riparian trees in highly saline environments, Australia.

    PubMed

    Costelloe, Justin F; Payne, Emily; Woodrow, Ian E; Irvine, Elizabeth C; Western, Andrew W; Leaney, Fred W

    2008-05-01

    The flow regimes of arid zone rivers are often highly variable, and shallow groundwater in the alluvial aquifers can be very saline, thus constraining the availability and quality of the major water sources available to riparian trees-soil water, shallow groundwater and stream water. We have identified water sources and strategies used by riparian trees in more highly saline and arid conditions than previously studied for riparian trees of arid zone rivers. Our research focused on the riparian species Eucalyptus coolabah, one of the major riparian trees of ephemeral arid zone rivers in Australia. The water sources available to this riparian tree were examined using delta(18)O isotope data from xylem, soil water, groundwater and surface water. Additionally, soil chloride and matric potential data were used to infer zones of water availability for root uptake. Despite the saline conditions, the trees used a mixture of soil water and groundwater sources, but they did not use surface water directly. The study identified three strategies used to cope with typically high groundwater and soil water salinities. Firstly, the trees preferentially grow in zones of most frequent flushing by infiltrating streamflow, such as the bank-tops of channels. Secondly, the trees limit water use by having low transpiration rates. Thirdly, the trees are able to extract water at very low osmotic potentials, with water uptake continuing at chloride concentrations of at least 20,000-30,000 mg L(-1). PMID:18270743

  16. A review of stratigraphy and sedimentary environments of the Karoo Basin of South Africa

    NASA Astrophysics Data System (ADS)

    Smith, R. M. H.

    The Karoo Supergroup covers almost two thirds of the present land surface of southern Africa. Its strata record an almost continuous sequence of continental sedimentation that began in the Permo-Carboniferous (280 Ma) and terminated in the early Jurassic 100 million years later. The glacio-marine to terrestrial sequence accumulated in a variety of tectonically controlled depositories under progressively more arid climatic conditions. Numerous vertebrate fossils are preserved in these rocks, including fish, amphibians, primitive aquatic reptiles, primitive land reptiles, more advanced mammal-like reptiles, dinosaurs and even the earliest mammals. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo sequence demonstrates the effects of more localised tectonic basins in influencing depositional style. These are superimposed on a basinwide trend of progressive aridification attributed to the gradual northward migration of southwestern Gondwanaland out of polar climes and accentuated by the meteoric drying effect of the surrounding land masses. Combined with progressive climatic drying was a gradual shrinking of the basin brought about by the northward migration of the subducting palaeo-Pacific margin to the south. Following deposition of the Cape Supergroup in the pre-Karoo basin there was a period of uplift and erosion. At the same time the southern part of Gondwana migrated over the South Pole resulting in a major ice-sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in both upland valley and shelf depositories resulted in the basal Karoo Dwyka Formation. After glaciation, an extensive shallow sea remained over the gently subsiding shelf fed by large volumes of meltwater. Black clays and muds accumulated under relatively cool climatic conditions (Lower Ecca) with perhaps a warmer "interglacial" during which the distinctive Mesosaurus-bearing, carbonaceous shales of the Whitehill Formation were deposited. Deformation of the southern rim of the basin, caused by the subducting palaeo-Pacific plate, resulted in mountain ranges far to the south. Material derived from this source, as well as granitic uplands to the west and morth-east, was deposited on large deltas that built out into the Ecca sea (Upper Ecca). The relatively cool climate and lowland setting promoted thick accumulations of peat on the coastal and delta plains and which now constitute the major coal reserves of southern Africa. Later the prograding deltas coalesced to fill most of the basin after which fluvial sedimentation of the Beaufort Group dominated. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. The central parts of the basin were for the most part drained by fine-grained meanderbelts and semi-permanent lakes. Significant stratabound uranium reserves have been delimited in the channel sandstones of the Beaufort Group in the southwestern parts of the basin. Pulses of uplift in the southern source areas combined with a possible orogenic effect resulted in two coarser-grained alluvial fans prograding into the more central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo sequence progressive aridification dominated depositional style with playa lake and wadi-type environments (Elliot Formation) that finally gave way to a dune sand dominated system (Clarens Formation). Basinwide volcanic activity of the early Jurassic Drakensberg Group brought deposition in the Karoo Basin to a close.

  17. Paleogeographic and paleotectonic setting of sedimentary basins in the Sevier thrust belt and hinterland, eastern Great Basin

    SciTech Connect

    Schmitt, J.G. . Dept. of Earth Sciences); Vandervoort, D.S. . Dept. of Geological Sciences); Suydam, J.D. . Dept. of Geology)

    1993-04-01

    The eastern Great Basin contains a sparse record of broadly distributed Cretaceous sedimentary rocks which record: evolution of intermontane basins during development of the Sevier (Sv)contractional orogen and incipient extensional collapse of the elevated Sv hinterland (east-central NV), and complex tectono-sedimentary interactions between frontal thrust belt structures and the western margin of the adjacent foreland basin. Palinspastic restoration of these strata and associated structures to pre-Tertiary extension positions reveals a clearer pictures of Cretaceous basin paleogeography and allows comparison with the Puna/Altiplano plateau and precordillera thrust belt of the Neogene Andean orogen. Two syntectonic stratal assemblages are present in east-central NV. Lower Cretaceous alluvial strata (Newark Canyon Fm) record basin development coeval with emergence of contractional structures in the Sv hinterland. Localized early Cretaceous basins were possibly piggyback immature; periods of open drainage to the to the east and south suggest connection with the nascent Sv foreland basin to the east (Cedar Mountain/Sanpete Fms) prior to major thrust loading in central Utah. Development of hinterland structures is almost recorded by Aptian-Albian foreland basin alluvial deposits in SW Utah (Dakota Fm) and southern Nevada (Willow Tank Fm). Upper Cretaceous to Eocene strata (Sheep Pass Fm) record inception of regionally abundant alluvial-lacustrine basins which developed in response to onset of latest Cretaceous extension and associated collapse of the Sv hinterland. Evolution of the structurally complex western margin of the Sv foreland basin is recorded in Cretaceous through Eocene strata deposited in: piggyback basins which were at times hydrologically connected to the adjacent foreland basins, and thrust-proximal portions of the foreland basin. These proximal areas are characterized by folding and faulting of basin fill and development of intrabasinal unconformities.

  18. Quaternary climate change and hillslope processes: What can we learn from alluvial fans?

    NASA Astrophysics Data System (ADS)

    Kenworthy, M.; Pierce, J. L.; Rittenour, T. M.; Sharp, W. D.; Pierce, K. L.

    2009-12-01

    Examining the timing of sediment deposition on alluvial fans may clarify relationships among Quaternary changes in climate, sediment production, and sediment removal from uplifted mountain blocks. Deposition on fans indicates that (1) ample sediment is available for transport within contributing basins and (2) that stream power is adequate to move that sediment to the fan environment. Dating alluvial fan deposition clarifies relationships among climatically controlled factors (e.g. precipitation, vegetation, temperature), and hydrologic and geomorphic responses (e.g. weathering rates, frost action, glaciation, stream power) that influence landscape evolution. Numerous 2-5 km radius, low gradient alluvial fans head along the western side of the Lost River Range (LRR) in east-central Idaho. Timing of deposition on these fans is based on optically stimulated luminescence dating (OSL). In addition we described general deposit characteristics and mapped different aged fan surfaces to explore how fan deposition has changed over time. OSL results indicate that evacuation of sediment from contributing basins and deposition on fans was enhanced ~10-14 ka and ~40-50 ka. The younger episode is more robust in this record, with deposition recorded on all five studied fans despite differences in Quaternary glacial extent in contributing basins that varied from ~0-80%. Glacial chronologies from the nearby Sawtooth Range (Thackray, 2008) and Yellowstone-Teton region (Licciardi and Pierce, 2008; Gosse et al, 1995) suggest that this time period may have coincided with and followed the last glacial maxima in the northern Rocky Mountains. Deposition during the ~40-50 ka episode is recorded on the two largest studied fans, both with <10% glaciation in basin areas, as well as a ~40 m terrace of the East Fork Big Lost River that drains the Pioneer Range west of the LRR. A ~60-65 ka moraine in the northern LRR dated by U-series on pedogenic carbonate, an extensive glacio-fluvial terrace in the Wind River Basin (~200 km east of the LRR) dated to >55 ± 8.6 ka (Sharp et al, 2003), and substantial loess accumulation near the Teton Range at ~46-54 ka (Pierce et al, personal comm.) suggest that this episode of fan deposition was late- to post-glacial with respect to the MIS 4 glaciation and associated climatic conditions. Deposition on alluvial fans generally results from (1) increases in the sediment supply and/or (2) changes in stream power that alter the relative balance between sediment supply and stream power. In this region, sediment supply could increase following glacial conditions if reduced effective moisture decreases hillslope vegetation cover, freeing accumulated regolith for transport to fans, or greater temperature fluctuations increase the effectiveness of frost weathering. Stream power following a glacial maxima may have decreased in response to effectively drier climate, but may still have been adequate to transport sediment to fans. It’s also possible that stream power increased following glacial maxima with greater frequency of stochastic events such as rain on snow.

  19. Caribbean basin framework, 3: Southern Central America and Colombian basin

    SciTech Connect

    Kolarsky, R.A.; Mann, P. )

    1991-03-01

    The authors recognize three basin-forming periods in southern Central America (Panama, Costa Rica, southern Nicaragua) that they attempt to correlate with events in the Colombian basin (Bowland, 1984): (1) Early-Late Cretaceous island arc formation and growth of the Central American island arc and Late Cretaceous formation of the Colombian basin oceanic plateau. During latest Cretaceous time, pelagic carbonate sediments blanketed the Central American island arc in Panama and Costa Rica and elevated blocks on the Colombian basin oceanic plateau; (2) middle Eocene-middle Miocene island arc uplift and erosion. During this interval, influx of distal terrigenous turbidites in most areas of Panama, Costa Rica, and the Colombian basin marks the uplift and erosion of the Central American island arc. In the Colombian basin, turbidites fill in basement relief and accumulate to thicknesses up to 2 km in the deepest part of the basin. In Costa Rica, sedimentation was concentrated in fore-arc (Terraba) and back-arc (El Limon) basins; (3) late Miocene-Recent accelerated uplift and erosion of segments of the Central American arc. Influx of proximal terrigenous turbidites and alluvial fans in most areas of Panama, Costa Rica, and the Colombian basin marks collision of the Panama arc with the South American continent (late Miocene early Pliocene) and collision of the Cocos Ridge with the Costa Rican arc (late Pleistocene). The Cocos Ridge collision inverted the Terraba and El Limon basins. The Panama arc collision produced northeast-striking left-lateral strike-slip faults and fault-related basins throughout Panama as Panama moved northwest over the Colombian basin.

  20. A landscape-scale study of land use and parent material effects on soil organic carbon and total nitrogen in the Konya Basin, Turkey

    NASA Astrophysics Data System (ADS)

    Mayes, M. T.; Marin-Spiotta, E.; Ozdogan, M.; Erdogan, M. A.

    2011-12-01

    In ecosystems where intensive farming and grazing have been occurring for millennia, there is poor understanding of how present-day soil biogeochemical properties relate to factors associated with soil parent materials (e.g. texture, mineralogy), and the net effects of long-term land use practices. Soil organic carbon (SOC) and total soil nitrogen (TN) are important for their roles in maintaining soil structure, moisture, fertility and contributing to carbon sequestration. Our research used a state factor approach (Jenny 1981) to study effects of soil parent materials and land use practices on SOC, TN, and other properties across thirty-five sites in the Konya Basin, an arid region in south-central Turkey farmed and grazed for over 8,000 years. This project is one of the first to study land use impacts on soils at a landscape scale (500 km2) in south-central Turkey, and incorporate geospatial data (e.g. a satellite imagery-derived land cover map we developed) to aid selection of field sites. Focusing on the plough layer (0-25cm) in two depth intervals, we compared effects of agriculture, orchard cultivation and grazing land use practices and clay-loam alluvial, sandy-loam volcanic and lacustrine clay soils on soil properties using standard least squares regression analyses. SOC and TN depended strongly on parent materials, but not on land use. Averaged across both depth intervals, alluvial soil SOC and TN concentrations (19.4 ± 1.32 Mg/ha SOC, 2.86 ± 1.23 Mg/ha TN) were higher and significantly different than lacustrine (9.72 ± 3.01 Mg/ha SOC, 1.57 ± 0.69 Mg/ha TN) and volcanic soil concentrations (7.40 ± 1.72 Mg/ha SOC, 1.02 ± 0.35 Mg/ha TN). Land use significantly affected SOC and TN on alluvial soils, but not on volcanic or lacustrine soils. Our results demonstrate the potential for land use to have different effects on different soils in this region. Our data on SOC, TN and other soil properties illustrate patterns in regional SOC and TN variability not shown by previous modeling or soil survey efforts. We provide baseline information on SOC and TN that can inform benchmarks for future soil monitoring and land use planning in an arid region that is likely to be highly impacted by future climatic changes, agricultural intensification and urban development. Our results suggest the importance of accounting for soil physical properties, and land use effects that are dependent on soil parent materials in future efforts to model or account for SOC and TN in similar ancient agricultural landscapes.

  1. Loess is the accumulation of dust, not evidence for aridity

    NASA Astrophysics Data System (ADS)

    Zech, Roland

    2013-04-01

    Loess-paleosol sequences (LPS) are valuable terrestrial archives for Quaternary climate and environmental changes. The famous sections on the Chinese Loess Plateau, for example, document the alternation of warm and humid interglacials (paleosols) and cold and more arid glacials (loess). This, at least partly, reflects the weakening of the monsoonal circulation during glacials and has led to the notion that loess in general documents more arid conditions. Paleosols, on the other hand, are often interpreted to document more humid conditions. We studied the LPS Crvenka in the Carpathian Basin, southeast Europe, which spans the full last glacial cycle, and obtained results that do not fit the above concept: (i) The analysis of plant-derived long-chain n-alkanes indicates the presence of deciduous trees and shrubs during glacials, i.e. sufficient precipitation for tree growth, whereas tree-less grass steppes seem to have prevailed during the Eemian, the last interglacial. (ii) Compound-specific deuterium analyses on the alkanes show only little changes on glacial-interglacial timescale. When compared with the isotopic enrichment of the Mediterranean Sea during the last glacial, this likely documents a combination of increased rainfall, reduced evapo-transpiration and reduced temperatures. (iii) Novel lipid biomarkers derived from soil bacteria (GDGTs, glycerol dialkyl glycerol tetraethers) also indicate humid glacials (BIT index close to 1) and more arid interglacials (BIT<0.8). Our results are in good agreement with modelling studies suggesting a southward shift of the westerlies during glacials, and aridization in the Mediterranean area in response to man-made global warming. More importantly, they remind us of an important fact: Loess is the accumulation of dust, but not (necessarily) evidence for aridity. Pedogenesis may simply not have been able to keep pace with high glacial dust accumulation rates related to intense glacial, periglacial and fluvial activity. Proxies independent of accumulation rates should be further developed and applied in LPS.

  2. Characterization of alluvial formation by stochastic modelling of paleo-fluvial processes: The concept and method

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenjiao; Mariethoz, Gregoire; Farrell, Troy; Schrank, Christoph; Cox, Malcolm

    2015-05-01

    Modelling fluvial processes is an effective way to reproduce basin evolution and to recreate riverbed morphology. However, due to the complexity of alluvial environments, deterministic modelling of fluvial processes is often impossible. To address the related uncertainties, we derive a stochastic fluvial process model on the basis of the convective Exner equation that uses the statistics (mean and variance) of river velocity as input parameters. These statistics allow for quantifying the uncertainty in riverbed topography, river discharge and position of the river channel. In order to couple the velocity statistics and the fluvial process model, the perturbation method is employed with a non-stationary spectral approach to develop the Exner equation as two separate equations: the first one is the mean equation, which yields the mean sediment thickness, and the second one is the perturbation equation, which yields the variance of sediment thickness. The resulting solutions offer an effective tool to characterize alluvial aquifers resulting from fluvial processes, which allows incorporating the stochasticity of the paleoflow velocity.

  3. Reconnaissance mapping of likely alluvial valley floors in five western states

    SciTech Connect

    Schmidt, J.C.; Nimick, D.A.

    1984-12-01

    Regional mapping of areas which potentially qualify as alluvial valley floors has been conducted under contract to the Office of Surface Mining in important coal fields of west-central North Dakota, central Utah, western Colorado, and the entire Powder River basin. Reconnaissance-level data were collected on the hydrology, geomorphology, and agricultural practices in each study area. Identification of unconsolidated deposits found in valleys was based on interpretation of aerial photography, topographic and geologic maps, and field data. Surface-irrigated sites were mapped based on irrigation surveys and an extensive regional inventory conducted during this project. An analysis of patterns of agricultural practices, physiography, geomorphology, and climate resulted in the designation of broad regions with similar styles of irrigation development. Criteria for assigning irrigation capability were developed for each region based on the irrigation practices and key physical components of the developed drainages. Subirrigated areas were interpreted from Landsat imagery taken during the moisture-stress period of mid- to late summer in five different years. Site-specific data available for small areas were used to calibrate the Landsat interpretation. These maps can be useful for planning and decision-making to regulatory and land management agencies as well as industry and public interest groups; they provide a regional perspective of the different components of alluvial valley floors and guidance regarding environmental concerns specific to each valley.

  4. Effects of the Biofuels Initiative on Water Quality and Quantity in the Mississippi Alluvial Plain

    NASA Astrophysics Data System (ADS)

    Welch, H. L.; Green, C. T.; Coupe, R. H.

    2010-12-01

    In the search for renewable fuel alternatives, biofuels have gained strong political momentum. In the last decade, extensive mandates, policies, and subsidies have been adopted to foster the development of a biofuels industry in the United States. The manifestation of the Biofuels Initiative in the Mississippi Delta was a 47-percent decrease in cotton acreage with a concurrent 288 percent increase in corn acreage in 2007. Because corn uses 80 percent more water for irrigation than cotton, and more nitrogen fertilizer is recommended for corn cultivation, this crop type change has implications for water quantity and quality in the Delta. Increased water use for corn is accelerating water-level declines in the Mississippi River Valley alluvial aquifer at a time when conservation is being encouraged due to concerns about sustainability. A mathematical model calibrated to existing conditions in the Delta shows that increased fertilizer applications on corn will increase the extent of nitrate movement into the alluvial aquifer. Estimates based on surface-water modeling results indicate that higher application rates of nitrogen from increased corn production increases the amount of nitrogen exported from the Yazoo River basin to the Gulf of Mexico by about 7 percent; increasing the Delta’s contribution to hypoxic conditions in the Gulf of Mexico.

  5. Martian alluvial fans and fan deltas as climate archives using analogue laboratory experiments

    NASA Astrophysics Data System (ADS)

    Kleinhans, M.; Postma, G.; van Dijk, M.

    The climate and hydrological conditions on early Mars have been the subject of heated debate in the past 40 years. The presence of deltas and fans, e.g. in crater lakes, is evidence for flowing water, but the duration of hydrological activity is highly uncertain. Deltas and fans come in an amazing variety of sizes and morphologies, which contains information on past hydrological conditions and changes therein. The aim of this work is to develop concepts and models to infer past hydrological conditions from delta and fan morphology. The methodology is to compare the Martian cases to deltas and fans created in highly controlled laboratory conditions, supported by palaeo-reconstruction of flow and sediment transport modelling for the Martian cases. We studied the autogenic (self-organised) and allogenic (forced) morphologies of alluvial fans and deltas based on experiments under constant boundary conditions as well as with changing upstream or downstream boundary conditions. The upstream conditions were water and sediment input into a feeder channel (reflecting hydrology and sediment delivery) and the downstream condition was basin water level (reflecting crater lake overflow level). The two experimental basins were 3x3.4m and 1m deep, and 6x8m and 2m deep. Detailed DTMs were collected during the experiments, which typically had durations of days to months. For deltas the water level above the initial sand bed was of the order of cm-s and was varied in some experiments, whereas for alluvial fans the initial beds emerged above the ground water surface in the tank. Based on our experiments with cohesionless sand producing bed load dominated systems representative of gravel systems at the natural terrestrial and martian scales, the following results were obtained. (1) Under constant boundary conditions, the surface slope is constant over time while the fan builds out quasi-radially. Smaller fans and fan deltas have an autogenic quasi-periodic alternation between channelised flow and unconfined sheet flow. Larger systems have frequent avulsing of the active depositional sectors. Shallow basins and higher discharge/sediment ratios show more fingering deltas and deep basins and smaller ratios more rounded fan deltas. (2) An increase of discharge (or decrease of sediment input) generally decreases the surface slope, causing excavation on (initially) the upper delta and unconfined flooding on the lower delta, whereas a decrease of discharge causes steepening of the upper delta. The slope follows directly from the ratio of discharge and sediment for a certain grain size. (3) The height of the delta foreset is directly related to basin depth and any changes therein 1 can be interpreted in terms of base (lake) level change. A rise of the water level causes the formation of second, backstepping deltas on top of the first delta, whereas a fall causes incision of a relatively narrow channel on the lower delta and the building out of secondary delta lobes. The absence of a water-filled basin in the cases of alluvial fans causes a more fingered fan shape with a channelised run-off system at the base of the fan. In literature some crater lake deltas with various terraces have been described, which must be interpreted as a (perhaps event-wise) increase of lake water level. The relatively simple morphology of many fans and deltas indicate a simple basin depth history compared to systems on Earth. Other examples will be given. Palaeoflow reconstruction and sediment transport modelling indicates that typical deltas and channels on Mars may have formed in less than thousands of years. Gravity directly affects the flow and sediment transport rate but this is well known and captured in common, well non-dimensionalised numbers in the models. The effect on the overall morphology of gravity differences between Mars and Earth is negligible compared to that of the other factors. 2

  6. Problems and Prospects of SWAT Model Application on an Arid/Semi-Arid Watershed in Arizona

    EPA Science Inventory

    In arid/semi-arid regions, precipitation mainly occurs during two periods: long-duration, low-intensity rainfall in winter; and short-duration, high-intensity rainfall in summer. Watersheds in arid/semi-arid regions often release water almost immediately after a storm due to spa...

  7. Understanding Hydrologic Processes in Semi-Arid Cold Climates

    NASA Astrophysics Data System (ADS)

    Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

    2004-12-01

    Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition, because precipitation patterns in this semi-arid region tend to be temporally distributed, storage and global climate change issues are significant.

  8. Digital-model simulation of the Toppenish alluvial aquifer, Yakima Indian Reservation, Washington

    USGS Publications Warehouse

    Bolke, E.L.; Skrivan, James A.

    1981-01-01

    Increasing demands for irrigating additional lands and proposals to divert water from the Yakima River by water users downstream from the Yakima Indian Reservation have made an accounting of water availability important for present-day water management in the Toppenish Creek basin. A digital model was constructed and calibrated for the Toppenish alluvial aquifer to help fulfill this need. The average difference between observed and model-calculated aquifer heads was about 4 feet. Results of model analysis show that the net gain from the Yakima River to the aquifer is 90 cubic feet per second, and the net loss from the aquifer to Toppenish Creek is 137 cubic feet per second. Water-level declines of about 5 feet were calculated for an area near Toppenish in response to a hypothetical tenfold increase in 1974 pumping rates. (USGS)

  9. Identification of recharge zones in the Lower Mississippi River alluvial aquifer using high-resolution precipitation estimates

    NASA Astrophysics Data System (ADS)

    Dyer, Jamie; Mercer, Andrew; Rigby, James R.; Grimes, Alexandria

    2015-12-01

    Water resources in the lower Mississippi River alluvial valley play a critical role in agricultural productivity due to the widespread use of irrigation during the growing season. However, the unknown specifics of surface-atmosphere feedbacks in the region, along with diminishing groundwater availability and the non-sustainable trend in irrigation draws from the alluvial aquifer, makes it difficult for water resource managers to make sound decisions for future water sustainability. As a result, it is crucial to identify spatial and temporal associations between local rainfall patterns and groundwater levels to determine the influence of precipitation on regional aquifer recharge. Specifically, it is critical to define the recharge zones of the aquifer so that rainfall distribution can be used to assess potential groundwater recovery. This project addresses the issue of defining areas of recharge in the lower Mississippi River alluvial aquifer (LMRAA) through an assessment of historical precipitation variability using high-resolution radar-derived precipitation estimates. A rotated principal component analysis (RPCA) of both groundwater and precipitation data from October through April is used to define locations where aquifer levels show the greatest variability, with a stepwise regression approach used to define areas where rainfall and groundwater levels show the strongest association. Results show that the greatest recharge through direct rainfall is along the Tallahatchie River basin in the northeastern Mississippi Delta, with recharge along the periphery of the LMRAA likely a result of direct water flux from surface hydrologic features.

  10. Preservation of daily tidal cycles and stacked alluvial swamp deposits: Depositional response to early compaction of buried peat bodies

    SciTech Connect

    Demko, T.M.; Gastaldo, R.A. )

    1990-05-01

    The character of the clastic depositional environments represented in the lower Mary Lee coal zone of the Pennsylvanian Pottsville Formation in the Warrior basin Alabama (tidally influenced mud flats and alluvial swamps) was controlled by the compaction of buried peat bodies. The lowest mineable coal in the Mary Lee coal zone, the Jagger, is overlain by laminated shale and sandstone exhibiting pronounced cycle bedding. This bedding records daily tidal cyclicity in the form of sand-mud couplets. These correspond to flood-current deposition of the coarser fraction followed by fallout of the finer grained fraction during ensuing slack-water periods. These couplets are cyclically bundled-sandier bundles corresponding to spring tides and muddier bundles to neap tides (lamination counts suggest a 24-30-day cycle). The clastic sequence above the overlying Blue Creek coal is characterized by a series of stacked alluvial swamp horizons. These can be identified by autochthonous fossil plants and pedological features indicative of gleyed paleosols. Catastrophic flooding buried and preserved these horizons. The rapid, early compaction of the buried Jagger and Blue Creek peat bodies created accommodation space that allowed both the preservation of tidalites in the Jagger coal to Blue Creek coal interval and the stacking of alluvial swamp paleosols above the Blue Creek seam. Carboniferous peats were comprised of highly compressible plant parts and hence, were sensitive to sediment loading. Once the peat bodies had compressed to a certain extent, stability of the overlying sediment surface created conditions amenable to resumption of peat accumulation.

  11. Dynamics of Bedload Transport in a Bedrock-Alluvial River

    NASA Astrophysics Data System (ADS)

    Hodge, R. A.; Sharma, B. P.; Ferguson, R.; Hardy, R. J.; Warburton, J.

    2014-12-01

    The processes controlling the entrainment, transport and deposition of coarse sediment in bedrock-alluvial systems are key for understanding sediment fluxes in these systems. Theories have been developed for these processes, and assumptions are made about them in models of bedrock incision. However, there are relatively few field datasets from these rivers with which to test these ideas. We report results from a gravel tracer experiment in the bedrock-alluvial Trout Beck, UK. The 410 m long study section consists of alluvial, mixed bedrock-alluvial and bedrock reaches. There are no tributary inputs so discharge is constant throughout. Two sets of 270 magnet-tagged pebbles covering the grain size distribution of the in-situ sediment were seeded in August 2013. Tracers were placed in an alluvial reach and in a bedrock reach, enabling quantification of grain dynamics over different substrates but under the same flow conditions. Tracers were resurveyed six times over nine months. Concurrent measurements of stage, discharge and bedload impacts at various locations in the channel aid interpretation of the tracer measurements. Tracers installed in the bedrock reach were far more mobile than those in the alluvial reach, with mean travel distances of 70.6 and 2.4 m respectively in the first two months. The transport of tracers was largely size independent over the purely bedrock reach. This finding may be explained by bulk hydraulic measurements that indicate that effective shear stress is highest in this section of the channel. Once these tracers reached the downstream mixed bedrock-alluvial reach, transport distances became relatively shorter, though still greater than in the purely alluvial reach (mean distances of 27.6 and 15.4 m from month 2 to month 7), and became size selective. The second set of tracers seeded in the alluvial reach displayed size-selective transport throughout the experimental period. This study demonstrates how reach substrate exerts a strong control on sediment mobility, through influence on both the sediment and the flow.

  12. A case for ancient evaporite basins on Mars

    NASA Astrophysics Data System (ADS)

    Forsythe, Randall D.; Zimbelman, James R.

    1995-03-01

    Observations indicate that a Martian analog to the Earth's salt pans and saline lakes of arid regions may have existed in crater-basins during Mars' early (Noachian) epoch. Terraced and channelized crater-basins point to ponding of surface water as well as possible prolonged and evolving base levels. In addition, supportive (evaporite basin) analogs are offered for three other morphologic features of Martian crater-basins. An evaporite basin model for crater-basins on Mars has major implications for the mechanical, chemical, and even biological processes that potentially have operated in Mars' past, and represent a spectrum of potential mineral resources. resources.

  13. Event scale variability of mixed alluvial-bedrock channel dynamics

    NASA Astrophysics Data System (ADS)

    Cook, Kristen; Turowski, Jens; Hovius, Niels

    2015-04-01

    The relationship between flood events and fluvial behavior is critical for understanding how rivers may respond to the changing hydrologic forcing that may accompany climate change. In mixed bedrock-alluvial rivers, the response of the system to a flood event can be affected by a large number of factors, including coarse sediment availability in the channel, sediment supply from the hillslopes, bedrock-controlled changes in channel width and planform, and the shape of the hydrograph. We use the Daan River Gorge in western Taiwan as a case study to directly observe the effect of individual flood events on channel evolution. The 1200 m long and up to 20 m deep bedrock gorge formed in response to uplift of the riverbed during the 1999 Chi-Chi earthquake. The extremely rapid pace of change ensures that flood events have measurable and often dramatic effects on the channel. Taiwan is subject to both summer typhoons and a spring monsoon, resulting in numerous channel-altering floods with a range of magnitudes. Discharge is therefore highly variable, ranging from 5 to over 2000 m3/s, and changes in the channel are almost entirely driven by discrete flood events. Since early 2009 we have monitored changes in the gorge with repeated RTK GPS surveys, laser rangefinder measurements, and terrestrial LIDAR surveys. Six rainfall stations and five water level gauges provide hydrological data for the basin. We find a distinct relationship between flood magnitude and the magnitude of geomorphic change; however, we do not find a clear relationship between flood characteristics and the direction of change - whether the channel experienced aggradation or erosion in a particular flood. Upstream coarse sediment supply and the influence of abrupt changes in channel width on bedload flux through the gorge appear to have important influences on the channel response. The better understand these controls, we use the model sedFlow (Heimann et al., 2014) to explore the effects of interactions between sediment supply, channel width, and flood characteristics on aggradation and erosion of the channel bed. Heimann, F. U. M., Rickenmann, D., Turowski, J. M., and Kirchner, J. W.: sedFlow - an efficient tool for simulating bedload transport, bed roughness, and longitudinal profile evolution in mountain streams, Earth Surf. Dynam. Discuss., 2, 733-772, doi:10.5194/esurfd-2-733-2014, 2014.

  14. A discontinuity in the late Pleistocene alluvial deposits, Hwacheon-ri, Gyeongju, Korea: Occurrences and paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Paik, In Sung; Kyeong Seol, Weon; Kim, Hyun Joo; Lee, Ho Il; Kang, Hee Cheol

    2015-04-01

    Sedimentary discontinuity surface occurs in the late Pleistocene alluvial deposits exposed along the cliff (about 10 m thick and over 140 m in length) in stream side, Gyeongju, Korea. The discontinuity surface is laterally extensive and marked by distinct carbonaceous dark horizon in the middle part of the deposits. The deposits are divided into lower and upper units by the discontinuity surface. The lower unit overlies unconformably the Cretaceous andesitic rock (basement), and consists of braided-river deposits. Lower part of the lower unit is mainly composed of lenticular-bedded and clast-supported conglomeratic deposits, whereas gray to dark gray sandy to muddy channel-plug deposits occur in the uppermost part of the lower unit. It is characteristic that iron-oxide crusts occur in the lower unit. They are cutting across the lower unit and truncated by the overlying upper unit. Rootlets mineralized by vivianite are present in the channel-plug deposits below the discontinuity surface. The upper unit overlying the lower unit with erosive contact (discontinuity surface) is mostly composed of matrix-supported conglomeratic alluvial fan deposits. Hornfelsic gravels are common in the lower unit, whereas andesitic gravels are predominant in the upper unit, suggesting the provenance change from the lower unit to the upper unit. OSL ages for the lower and the upper units are 125±9 ka and 94±9 ka, respectively, suggesting that the lower unit was deposited in MIS5e and the upper unit was formed in MIS5c to 5b. It is thus interpreted that the shift of depositional environment from a fluvial plain (lower unit) to an alluvial fan (upper unit) was an alluvial response to sea level change inducing fall of base level in an alluvial basin from the interglacial to the glacial stages. The development of iron-oxide crusts and diagenetic vivianite in the discontinuity surface suggest that humid condition persisted during the paleoclimatic shift from the last interglacial to the last glacial stages. Key words: Late Pleistocene, Alluvial deposits, Discontinuity, Iron-oxides, Vivianite

  15. Calibration of the ARID robot

    NASA Technical Reports Server (NTRS)

    Doty, Keith L

    1992-01-01

    The author has formulated a new, general model for specifying the kinematic properties of serial manipulators. The new model kinematic parameters do not suffer discontinuities when nominally parallel adjacent axes deviate from exact parallelism. From this new theory the author develops a first-order, lumped-parameter, calibration-model for the ARID manipulator. Next, the author develops a calibration methodology for the ARID based on visual and acoustic sensing. A sensor platform, consisting of a camera and four sonars attached to the ARID end frame, performs calibration measurements. A calibration measurement consists of processing one visual frame of an accurately placed calibration image and recording four acoustic range measurements. A minimum of two measurement protocols determine the kinematics calibration-model of the ARID for a particular region: assuming the joint displacements are accurately measured, the calibration surface is planar, and the kinematic parameters do not vary rapidly in the region. No theoretical or practical limitations appear to contra-indicate the feasibility of the calibration method developed here.

  16. Hydrological Responses to Climate Change and to LUCC in Asian Arid Zone

    NASA Astrophysics Data System (ADS)

    Feng, Zhaodong

    2013-04-01

    The arid Asian zone is one of the most sensitive areas to the global climate change. For instance, the temperature has been rising at a rate of 0.39K/10yrs in the arid northwestern China during the past an half of century, being 2.78 times of the global average. In the arid Asian zone, water resource is a key factor restricting the socio-economic development and threatening the ecological security. Under the global warming conditions, water resource systems of the arid Asian zone are most likely becoming increasingly vulnerable, especially under the projected increasing population and expanding economy in arid Asian zone. Hydrological data from glacier-supplied rivers in the Tian Shan Mountains for example show that the runoff has been increasing primarily as a result of rising temperature that caused increases in ice melting. But, the decreasing trend of surface runoff in low-elevation basins is undeniable and the decreasing trend is attributable to the increasingly intensified human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches of the arid river basins. In arid northwestern China, about 85% of the water resources are formed in high elevations and the glacier-melting contribution to runoff has been doubled since 1980's. Approaching to the turning point of glacier-melting supplies to runoff will pose a great threat to socio-economic sustainability and to ecological security. The turning point refers to the transition from increasing runoff to decreasing runoff within glacier-melting supplied watersheds under warming climate.

  17. Hydrological Response of Semi-arid Degraded Catchments in Tigray, Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Teka, Daniel; Van Wesemael, Bas; Vanacker, Veerle; Hallet, Vincent

    2013-04-01

    To address water scarcity in the arid and semi-arid part of developing countries, accurate estimation of surface runoff is an essential task. In semi-arid catchments runoff data are scarce and therefore runoff estimation using hydrological models becomes an alternative. This research was initiated in order to characterize runoff response of semi-arid catchments in Tigray, North Ethiopia to evaluate SCS-CN for various catchments. Ten sub-catchments were selected in different river basins and rainfall and runoff were measured with automatic hydro-monitoring equipments for 2-3 years. The Curve Number was estimated for each Hydrological Response Unit (HRU) in the sub-catchments and runoff was modeled using the SCS-CN method at ? = 0.05 and ? = 0.20. The result showed a significant difference between the two abstraction ratios (P =0.05, df = 1, n= 132) and reasonable good result was obtained for predicted runoff at ? = 0.05 (NSE = -0.69; PBIAS = 18.1%). When using the CN values from literature runoff was overestimated compared to the measured value (e= -11.53). This research showed the importance of using measured runoff data to characterize semi-arid catchments and accurately estimate the scarce water resource. Key words: Hydrological response, rainfall-runoff, degraded environments, semi-arid, Ethiopia, Tigray

  18. A summary of methods for the collection and analysis of basic hydrologic data for arid regions

    USGS Publications Warehouse

    Rantz, S.E.; Eakin, T.E.

    1971-01-01

    This report summarizes and discusses current methods of collecting and analyzing the data required for a study of the basic hydrology of arid regions. The fundamental principles behind these methods are no different than those that apply to studies of humid regions, but in arid regions the infrequent occurrence of precipitation, the great variability of the many hydrologic elements, and the inaccessibility of most basins usually make it economically infeasible to use conventional levels of instrumentation. Because of these economic considerations hydrologic studies in arid regions have been commonly of the reconnaissance type; the more costly detailed studies are generally restricted to experimental basins and to those basins that now have major economic significance. A thorough search of the literature and personal communication with workers in the field of arid-land hydrology provided the basis for this summary of methods used in both reconnaissance and detailed hydrologic studies. The conclusions reached from a consideration of previously reported methods are interspersed in this report where appropriate.

  19. Sedimentology and stratigraphy of Cenozoic deposits in the Kağızman-Tuzluca Basin, northeastern Turkey

    NASA Astrophysics Data System (ADS)

    Varol, Baki; Şen, Şevket; Ayyıldız, Turhan; Sözeri, Koray; Karakaş, Zehra; Métais, Grégoire

    2016-01-01

    The Kağızman-Tuzluca Basin is located in the northeastern Anatolia, to the east of the intersection point (near Karlıova) of the major North and East Anatolian Fault systems. This intermontane basin displays a thick sequence (over 2000 m) of mostly terrestrial deposits represented by repetitive alternations of the lake and fluvial environments ranging from ?Late Eocene/Oligocene to Middle/? Late Miocene. A marine incursion only mappable in the southeastern margin of the basin deposited limestones and sandy limestones rich in marine mollusks and nummulites, in particular N. fichteli that constrain an Early Oligocene age for this marine unit (Kağan Fm). The terrestrial basin-fill deposits show different thicknesses throughout the basin due to irregular bottom topography and tectonic configuration of the basin margins. The thickest deposits were accumulated along the different margins of the basin, which received high quantities of siliciclastics from meandering river, alluvial and coastal fans, fan delta/Gilbert-type delta and wave-worked fluvial delta. Climate changes have also driven the development of lake environments during distinct depositional periods. Siliciclastic-dominated overfilled lakes (Halıkışlak and Kızılkaya formations) and chemical-dominated underfilled lakes (Turabi and Tuzluca formations) were formed. They have been also classified as "Newark-type" and "Fundy-type" lakes, respectively. Fluvial systems evolved from high-energy meandering rivers deposited under humid climate (Güngören Formation) to low-energy meandering rivers resulted from arid and semiarid climates (Çincavat Formation). The transitional intervals from ephemeral river-dry mudflat (Çincavat Formation) to saline pan/lake (Tuzluca Formation) indicate wadi-sand flat-playa fluvial systems. The chronostratigraphic constrains of the entire sequence remain poor and so far solely based on vertebrate fossil assemblages. The evaporitic Tuzluca Formation would be Middle Miocene in age due to its stratigraphic position over the Çincavat Formation.

  20. Lake Murray, Fly and Strickland River Basins, Papua, New Guinea

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Lake Murray, a manmade reservoir, lies between the Fly and Strickland River Basins, Papua, New Guinea (7.0S, 141.5E). The region, photographed in sunglint, shows the water level in the reservoir and the full extent of the drainage basins of both river systems as the rivers meander through wide alluvial floodplains. Some forest clearing can be seen in places throughout the region, but most of the area remains in closed canopy forest.

  1. Characterizing avulsion stratigraphy in ancient alluvial deposits

    NASA Astrophysics Data System (ADS)

    Jones, H. L.; Hajek, E. A.

    2007-11-01

    Guidelines for identifying ancient avulsion deposits were set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268], building on the study by Smith et al. [Smith, N.D., Cross, T.A., Dufficy, J.P., Clough, S.R., 1989. Anatomy of an avulsion. Sedimentology 36, 1-23] of the modern Saskatchewan River system (Cumberland Marshes, central Canada), and serve to characterize avulsion depositional sequences in the ancient Willwood and Fort Union Formations (Paleogene, Bighorn Basin, NW Wyoming, USA). We recognize, however, that the model is not universally applicable to avulsion-dominated successions, specifically systems which lack defining "heterolithic avulsion deposits", set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268]. Observations in several fluvial intervals suggest that the avulsion stratigraphy outlined by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268] represents one category of avulsion stratigraphy found in the rock record, but does not capture the nature of avulsion deposits everywhere. Based on observations (using measured sections, outcrop photo-panels, and aerial photographs) in the Willwood Formation (Eocene, Wyoming) and Ferris Formation (Cretaceous/Paleogene, Wyoming), we present two end-member categories of avulsion stratigraphy in ancient deposits; stratigraphically abrupt, when a main paleochannel is stratigraphically juxtaposed directly atop floodplain/overbank deposits, and stratigraphically transitional, where crevasse splays and other non-floodplain/-overbank deposits stratigraphically precede a main paleochannel. This characterization provides a broader, more inclusive way to recognize and describe avulsion stratigraphy in ancient deposits and may be an important factor to consider when modeling connectivity in fluvial reservoirs. Furthermore, our observations show that one type of avulsion channel stratigraphy may prevail over another within an ancient basin, suggesting that system-wide factors such as splay-proneness or avulsion style (i.e. aggradational, incisional, etc.; [Slingerland, R., Smith, N.D., 2004. River avulsions and their deposits. Annual Review of Earth and Planetary Sciences 32, 257-285]) may be primary controls on the type of avulsion stratigraphy deposited and preserved in ancient basin-fills.

  2. Limited hydrological connectivity in arid and semi-arid areas

    NASA Astrophysics Data System (ADS)

    Yair, Aaron

    2014-05-01

    Many studies contend that runoff and erosion rate increase as slope angle and slope length increase. These studies have been often conducted in agricultural areas, on small plots with quite uniform surface conditions;and relatively low slope angles. Such an approach assumes flow continuity and sediment movement along whole hillslopes; or in other terms That runoff concentration time is shorter than the duration of most effective rain events. Question: Can we apply the above approach to dry-land areas where the concentration time, especially over long hillslopes is much longer than the duration of most effective rainshowers. Hydrological data collected at two small instrumented watersheds, located one in an arid rocky area and the other in a semi-arid area (90 and 280 mm average annual rainfall)point to a high frequency of flow discontinuity at the hillslope scale, as well as along channels of first order streams,even at extreme rain events. Connectivity at both scales is higher in the arid than in the semi-arid area. Flow discontinuity increases with increasing slope length. The frequent flow discontinuity at the hillslope scale leads to the development of colluvial deposits at the slope base; characterized by high infiltration rate, that limits flow connectivity at the hillslope-channel interface. THe frequent flow discontinuity in dry land areas is mainly explained by the intermittent character of most rain events. The duration of most effective rainshowers is much shorter than the concentration time require for a continuous flow from the top to the base of the flow. The long term effect of flow discontinuity is very well expressed by soil development along the colluvial mantle; whose upper part if far better leached than its lower oart

  3. Structure of Alluvial Valleys from 3-D Gravity Inversion: The Low Andarax Valley (Almería, Spain) Test Case

    NASA Astrophysics Data System (ADS)

    Camacho, Antonio G.; Carmona, Enrique; García-Jerez, Antonio; Sánchez-Martos, Francisco; Prieto, Juan F.; Fernández, José; Luzón, Francisco

    2015-11-01

    This paper presents a gravimetric study (based on 382 gravimetric stations in an area about 32 km2) of a nearly flat basin: the Low Andarax valley. This alluvial basin, close to its river mouth, is located in the extreme south of the province of Almería and coincides with one of the existing depressions in the Betic Cordillera. The paper presents new methodological work to adapt a published inversion approach (GROWTH method) to the case of an alluvial valley (sedimentary stratification, with density increase downward). The adjusted 3D density model reveals several features in the topography of the discontinuity layers between the calcareous basement (2,700 kg/m3) and two sedimentary layers (2,400 and 2,250 kg/m3). We interpret several low density alignments as corresponding to SE faults striking about N140-145°E. Some detected basement elevations (such as the one, previously known by boreholes, in Viator village) are apparently connected with the fault pattern. The outcomes of this work are: (1) new gravimetric data, (2) new methodological options, and (3) the resulting structural conclusions.

  4. MAP OF ECOREGIONS OF THE MISSISSIPPI ALLUVIAL PLAIN

    EPA Science Inventory

    The ecoregions of The Mississippi Alluvial Plain (73) have been identified, mapped, and described and provide a geographic structure for environmental resources research, assessment, monitoring, and management. This project is part of a larger effort by the U.S. EPA to create a ...

  5. HYDRAULIC ANALYSIS OF BASEFLOW AND BANK STORAGE IN ALLUVIAL STREAMS

    EPA Science Inventory

    This paper presents analytical solutions, which describe the effect of time-variable net recharge (net accretion to water table) and bank storage in alluvial aquifers on the sustenance of stream flows during storm and inter-storm events. The solutions relate the stream discharge,...

  6. Morphostructural characterization of the Charco basin and its surrounding areas in the Chihuahua segment of north Mexican Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Troiani, Francesco; Menichetti, Marco

    2014-05-01

    The Chihuahua Basin and Range (CBR) is the eastern branch of the northern Mexican Basin and Range Province that, from a morphostructural point of view, presently is one amongst the lesser-known zones of the southern portion of the North America Basin and Range Province. The study area covers an approximately 800 km2-wide portion of the CBR and encompasses the fault-bounded Charco basin and its surrounding areas. The bedrock of the area pertains to the large siliceous-igneous province of the Sierra Madre Occidental and consists of volcanoclastic rocks including Oligocene dacite, rhyolite, rhyolitic tuffs, and polimitic conglomerates. The region is characterized by a series of NW-SE oriented valleys delimited by tilted monoclinal blocks bounded by high angle, SW-dipping, normal faults. Abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins are the main morphological elements of the area. The valleys correspond to structural grabens filled with Plio-Pleistocene continental sediments. These grabens are about 10 km wide, while the extensional fault system extend over a distance of more than 15 km. The mountain ranges are in most cases continuous over distances that range from 10 to 70 km including different branches of the extensional and transfer faults. The morphogenesis is mainly erosive in character: erosional landforms (such as rocky scarps, ridges, strath-terraces, erosional pediment, reverse slopes, landslide scar zones, litho-structural flat surfaces) dominate the landscape. In contrast, Quaternary depositional landforms are mainly concentrated within the flat valleys or basins. The Quaternary deposits consist of wide alluvial fans extending to the foot of the main ridges, fluvial and debris-slope deposits. The morphostructural characterization of the area integrated different methodologies, including: i) geomorphological and structural field analyses; ii) remote sensing and geo-morphometric investigations based on aerial photos and Digital Elevation Models (a 28x28 m DEM and high-resolution LIDAR dataset in key sites), and iii) geophysical investigations (high resolution reflection seismic profiling combined with refraction seismic tomography). The main outputs of this research are as follows: i) the Charco basin master-faults and their conjugate extensional system were geometrically characterized and their main associated landforms mapped and described; ii) the morphostratigraphic correlations amongst both deformed and tectonically unaffected Quaternary deposits revealed that the Charco basin master fault has been inactive over the Holocene; iii) the main extensional fault system is associated with conjugate faults, oriented approximately SSW-NNE, that segmented the Charco basin master faults and favored the deposition of the most recent piedmont fans along the eastern margin of the basin; iv) the local morphostructures had played a dominant influence on the Quaternary evolution of both drainage network and relief landforms.

  7. Do invasive riparian Tamarix alter hydrology of riparian areas of arid and semi-arid regions under climate change scenarios?

    NASA Astrophysics Data System (ADS)

    Bhattarai, M. P.; Acharya, K.; Chen, L.

    2012-12-01

    Competitiveness of riparian invasive species, Tamarix, in arid and semi-arid riparian areas of the southwestern United States under climate change scenario (SRES A2) was investigated. Tamarix has been replacing native vegetation along the riparian corridors of these areas for the past several decades and is thought to alter water balance. Changes in depth to groundwater, soil moisture distribution and flood frequency are critical in survival and growth of a facultative phreatophyte such as Tamarix. In this study, a fully coupled 2d surface flow and 3d subsurface flow hydrologic model, HydroGeoSphere, was used to simulate surface-subsurface hydrology of the lower Virgin River basin (4500 sq. km), located in Nevada, Utah and Arizona. The hydrologic model results, depth to groundwater and soil saturation, were then applied to the species distribution model, Maxent, along with other bioclimatic parameters to asses future Tamarix distribution probability. Simulations were made for the climate scenarios of the end of 21st centry conditions. Depth to groundwater is found to be the most important predictor variable to the Maxent model. Future Tamarix distribution range is not uniform across the basin. It is likely to decrease at lower elevations and increase in some higher elevation areas.

  8. Modeling ground water flow in alluvial mountainous catchments on a watershed scale.

    PubMed

    Wolf, Jens; Barthel, Roland; Braun, Jürgen

    2008-01-01

    In large mountainous catchments, shallow unconfined alluvial aquifers play an important role in conveying subsurface runoff to the foreland. Their relatively small extent poses a serious problem for ground water flow models on the river basin scale. River basin scale models describing the entire water cycle are necessary in integrated water resources management and to study the impact of global climate change on ground water resources. Integrated regional-scale models must use a coarse, fixed discretization to keep computational demands low and to facilitate model coupling. This can lead to discrepancies between model discretization and the geometrical properties of natural systems. Here, an approach to overcome this discrepancy is discussed using the example of the German-Austrian Upper Danube catchment, where a coarse ground water flow model was developed using MODFLOW. The method developed uses a modified concept from a hydrological catchment drainage analysis in order to adapt the aquifer geometry such that it respects the numerical requirements of the chosen discretization, that is, the width and the thickness of cells as well as gradients and connectivity of the catchment. In order to show the efficiency of the developed method, it was tested and compared to a finely discretized ground water model of the Ammer subcatchment. The results of the analysis prove the applicability of the new approach and contribute to the idea of using physically based ground water models in large catchments. PMID:18459959

  9. Intelligent mapping of alluvial aquifer characteristics in the Otago region, New Zealand

    NASA Astrophysics Data System (ADS)

    Friedel, Michael; Rawlinson, Zara; Westerhoff, Rogier

    2015-04-01

    We adopt a hybrid approach to map the 3D hydrostratigraphy of an alluvial aquifer using big data collected in the Ettrick basin, Otago New Zealand. First, a subset (1%) of the 18 million regional helicopter frequency-domain electromagnetic (HEM) sounding measurements (300 Hz, Horizontal co-planar; 3300 Hz, vertical co-planar; 8200 Hz, horizontal co-planar; 40 kHz, horizontal co-planar; 137 kHz horizontal coplanar) and their numerically-inverted 1D resistivity (50¬-100 Ω-m) profiles are randomly split. For example, 50% of these data are used for training an unsupervised machine-learning (ML) network, and 50% of these data are used for performance at independent locations. The remaining set of HEM measurements are then presented to the vetted ML network to estimate regional resistivity structure which is compared to previously inverted resistivity. Second, about 50 borehole autocorrelation functions are computed based on cross-component correlations of quantized borehole locations sampled for lithology and HEM sounding data. Third, an unsupervised ML network is trained and performance tested using sparse borehole lithology (fractions of sand, silt, clay, mudstone, schist) and hydraulic properties (storage, hydraulic conductivity), and those HEM sounding data occurring within a radius defined by the maximum borehole autocorrelation distances. Fourth, this ML network is then used together with independent HEM sounding measurements to map the spatial distribution of physical aquifer properties and hydraulic properties across the basin.

  10. A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa

    NASA Astrophysics Data System (ADS)

    Smith, R. M. H.; Eriksson, P. G.; Botha, W. J.

    1993-02-01

    The Karoo Basin of South Africa was one of several contemporaneous intracratonic basins in southwestern Gondwana that became active in the Permo-Carboniferous (280 Ma) and continued to accumulate sediments until the earliest Jurassic, 100 million years later. At their maximum areal extent, during the early Permian, these basins covered some 4.5 million km 2. The present outcrop area of Karoo rocks in southern Africa is about 300 000 km 2 with a maximum thickness of some 8000 m. The economic importance of these sediments lies in the vast reserves of coal within the Ecca Group rocks of northern and eastern Transvaal and Natal, South Africa. Large reserves of sandstone-hosted uranium and molybdenum have been proven within the Beaufort Group rocks of the southern Karoo trough, although they are not mineable in the present market conditions. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo succession in South Africa demonstrates the changes in depositional style caused by regional and localized tectonism within the basin. These depocentres were influenced by a progressive aridification of climate which was primarily caused by the northward drift of southwestern Gondwana out of a polar climate and accentuated by the meteoric drying effect of the surrounding land masses. Changing palaeoenvironments clearly influenced the rate and direction of vertebrate evolution in southern Gondwana as evidenced by the numerous reptile fossils, including dinosaurs, which are found in the Karoo strata of South Africa, Lesotho, Namibia and Zimbabwe. During the Late Carboniferous the southern part of Gondwana migrated over the South Pole resulting in a major ice sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in upland valleys and on the lowland shelf resulted in the Dwyka Formation at the base of the Karoo Sequence. After glaciation, an extensive shallow sea covered the gently subsiding shelf, fed by large volumes of meltwater. Marine clays and muds accumulated under cool climatic conditions (Lower Ecca Group) including the distinctive Mesosaurus-bearing carbonaceous shales of the Whitehill Formation. Subduction of the palaeo-Pacific plate reslted in an extensive chain of mountains which deformed and later truncated the southern rim of the main Karoo Basin. Material derived from these "Gondwanide" mountains as well as from the granitic uplands to the north-east, accumulated in large deltas that prograded into the Ecca sea (Upper Ecca Group). The relatively cool and humid climate promoted thick accumulations of peat on the fluvial and delta plains which now constitute the major coal reserves of southern Africa. As the prograding deltas coalesced, fluvio-lacustrine sediments of the Beaufort Group were laid down on broad gently subsiding alluvial plains. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. Vegetation alongside the meander belts and semi-permanent lakes supported a diverse reptilian fauna dominated by therapsids or "mammal-like reptiles". Pulses of uplift in the southern source areas combined with possible orographic effects resulted in the progadation of two coarse-grained alluvial fans into the central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo Sequence, progressive aridification and tectonic deformation of the basin through the late Triassic and early Jurassic led to the accumulation, in four separate depositories, of "redbeds" which are interpreted as fluvial and flood-fan, playa and dune complexes (Elliot Formation). This eventually gave way to westerly wind-dominated sedimentation that choked the remaining depositories with fine-grained dune sand. The interdune areas were damp and occasionally flooded and provided a habitat for small dinosaurs and the earliest mammals. During this time (Early Jurassic), basinwide volcanic activity began as a precursor to the break-up of Gondwana in the late Jurassic and continued until the early Cretaceous. This extrusion of extensive flood basalts (Drakensberg Group) onto the Clarens landscape eventually brought Karoo sedimentation to a close.

  11. Landform map of the Kaiparowits Coal-Basin area, Utah

    SciTech Connect

    Sargent, K.A.; Hansen, D.E.

    1980-01-01

    A 1:125,000 scale map of the Kaiparowits Coal-Basin area of Utah is presented. The map portrays the shape and erosional resistance of and features, and it is intended to be a modified slope-analysis map for use by planners in their identification of areas suitable for transportation routes and construction sites. Depositional landforms such as alluvial flats, stream courses, dune fields, and alluviated pediments are shown, and a stratigraphic section of the rocks in the area is provided. (JMT)

  12. Stratigraphy of Pennsylvanian detrital reservoirs, Permian basin

    SciTech Connect

    Van Der Loop, M. )

    1992-04-01

    Significant oil reserves have been found to date in stratigraphic traps in Pennsylvanian detrital reservoirs on the Central Basin platform and Reagan uplift of the Permian basin. The 32 MMBOEG Arenoso field area, discovered in 1966, is the largest producing field. Along a 75 mi northwest-southeast trend, 23 other smaller fields will produce an average 850 MBOEG each, for a total estimated ultimate recovery to date in the trend of 52 MMBOEG. These stratigraphic traps are elusive and complex. However, reservoir quality is excellent, and because of the poorly understood trap types, significant reserves remain to be found in the trend. The Pennsylvanian detrital consists of chert cobble conglomerates, coarse sands, red shales, and gray limestones deposited in an environment that grades seaward from alluvial fan to braided stream to shallow marine. The chert cobble conglomerates of the alluvial fan facies and the coarse sands of the braided stream facies are the highest quality pay zones. Porosities range from 5 to 20%, with permeability ranging up to 26 d. The total unit is seldom more than 400 ft thick; reservoir rock thicknesses within the unit range up to 100 ft. Because of the complex nature of the alluvial fan and braided stream deposits, dry development wells can be expected within fields. These Strawn deposits are located adjacent to and overlying the eroded lower Paleozoic uplifts of the southern Central Basin platform. The major source of the chert cobbles is erosion of the Devonian tripolitic chert. Renewed structural uplift combined with sea level drop in the middle Wolfcampian locally truncated some Pennsylvanian detrital alluvial fan deposits, and complicated or destroyed a potential trap by depositing Wolfcamp chert conglomerates on top of the Pennsylvanian conglomerates.

  13. Geostatistical simulations of alluvial sandbodies in the Triassic series of the Chaunoy field, France

    SciTech Connect

    Eschard, R.; Desaubliaux, G.; Eemouzy, P. ); Bacchiana, C.; Parpant, J.; Chautru, J.M.

    1993-09-01

    Chaunoy field, the largest oil field of the Paris basin, is exploiting heterogeneous reservoirs deposited during the Triassic in a large alluvial fan/lacustrine complex. The construction of a realistic reservoir model is difficult in such a setting because of the highly complex architecture of single reservoir units. Geostatistical simulations therefore have been performed to take into account the reservoir heterogeneities in the fluid flow modeling. A first layering has been determined from sedimentological and sequence stratigraphic analysis. The series was deposited in an alluvial outer fan environment. A lower siliciclastic member shows four heterogeneous sand sheets (7 m thick), which have been correlated across the field. Each of them is made up of stacked single channel sequences. The sand sheets are separated by extensive lacustrine and flood plain mudstone layers acting as permeability barriers. An upper siliciclastic/dolomitic member has been divided into two units with porous conglomeratic channels interfingered with cemented lagoonal dolomites. Proportional curves in lithofacies have confirmed this layering, showing the continuity of the permeability barriers, and the variogram analysis has shown that the well spacing is larger than the channel width. Simulations in lithofacies have been performed with the Heresim software using three different variogram ranges (small, medium, and large values). Because a good correlation exists between the lithofacies and the petrophysical attributes, a transcription of the lithofacies simulations into petrophysical attributes therefore was easy and realistic. Scaling-up techniques have given fluid-flow models corresponding to the three correlation ranges. Comparison of the global results of the fluid flow simulations with the observed production history enabled us to choose the more relevant case. The the model using the selected correlation range helped determine optimum well spacing.

  14. Channel Dynamics on Experimental Alluvial Fans with a Bimodal Grain Size Distribution

    NASA Astrophysics Data System (ADS)

    Reitz, M. D.; Moberg, E.; Jerolmack, D. J.

    2008-12-01

    Alluvial fans in arid regions often display two striking patterns: a strongly bimodal grain size distribution of boulders and sand, and a network of well-defined distributary channels even in the absence of cohesive sediment. The spatial distribution of grain sizes is qualitatively linked with the channel network on the fan, with the boulders tending to line the bed and banks of channels. We hypothesize that spatial grain size sorting of a bimodal sediment supply gives rise to persistent channelization under these noncohesive conditions. Using a scaled-down bimodal grain size distribution in the lab, we build alluvial fans under sediment and water input conditions that typically produce sheet flow and ephemeral channels when a single grain size is used. The first order pattern is gradual downstream fining on the upper fan, and the formation of an abrupt boulder/sand transition and its corresponding distinct slope break in the middle fan. Superimposed on this trend is the formation and relocation of well-defined channels which form distributary networks similar to those observed in nature, and which typically require cohesive sediment mixtures to simulate experimentally. We observed the following sequence of channel creation and abandonment: (1) Spontaneous channel formation focuses flow, leading to (2) localized, rapid shoreline progradation at the channel mouth, lowering the fluvial slope and causing (3) aggradation and rapid channel backfilling, leading to (4) abandonment of the filled channel and flooding of the fan surface. Flooding activates numerous small channels and (5) eventually one of the flowpaths - typically having a substantially steeper slope than the previous channel - begins to downcut and focus the flow, leading to formation of a new dominant channel and corresponding lobe at the front of the fan. We varied the relative fraction of our two grain sizes, and also their relative mobility, in order to explore controls on fan formation and channel dynamics. We present results characterizing the co-evolution of surface grain size distribution, fan topography and channel network dynamics through time. Experiments demonstrate a characteristic timescale for avulsion and lobe switching, which we quantitatively link to sediment supply.

  15. Probable flood predictions in ungauged coastal basins of El Salvador

    USGS Publications Warehouse

    Friedel, M.J.; Smith, M.E.; Chica, A.M.E.; Litke, D.

    2008-01-01

    A regionalization procedure is presented and used to predict probable flooding in four ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. The flood-prediction problem is sequentially solved for two regions: upstream mountains and downstream alluvial plains. In the upstream mountains, a set of rainfall-runoff parameter values and recurrent peak-flow discharge hydrographs are simultaneously estimated for 20 tributary-basin models. Application of dissimilarity equations among tributary basins (soft prior information) permitted development of a parsimonious parameter structure subject to information content in the recurrent peak-flow discharge values derived using regression equations based on measurements recorded outside the ungauged study basins. The estimated joint set of parameter values formed the basis from which probable minimum and maximum peak-flow discharge limits were then estimated revealing that prediction uncertainty increases with basin size. In the downstream alluvial plain, model application of the estimated minimum and maximum peak-flow hydrographs facilitated simulation of probable 100-year flood-flow depths in confined canyons and across unconfined coastal alluvial plains. The regionalization procedure provides a tool for hydrologic risk assessment and flood protection planning that is not restricted to the case presented herein. ?? 2008 ASCE.

  16. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon.

    PubMed

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-01-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their (13)C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m(-2), which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21-49 g C m(-2) year(-1)) than SOC (10-39 g C m(-2) year(-1)) over 0-20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China. PMID:26091554

  17. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon

    PubMed Central

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-01-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their 13C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m−2, which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21–49 g C m−2 year−1) than SOC (10–39 g C m−2 year−1) over 0–20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China. PMID:26091554

  18. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon

    NASA Astrophysics Data System (ADS)

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-06-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their 13C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2?kg C m-2, which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21-49?g C m-2 year-1) than SOC (10-39?g C m-2 year-1) over 0-20?cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China.

  19. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

    NASA Astrophysics Data System (ADS)

    Timms, W. A.; Young, R. R.; Huth, N.

    2011-11-01

    The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr-1 rainfall), such as parts of Australia's Murray-Darling Basin (MDB). In this unique study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha-1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ?10 m depth that is not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m-1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m-1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr-1 (0.7-2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditionsafter changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

  20. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

    NASA Astrophysics Data System (ADS)

    Timms, W. A.; Young, R. R.; Huth, N.

    2012-04-01

    The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr-1 rainfall, potential evapotranspiration >2000 mm yr-1) such as parts of Australia's Murray-Darling Basin (MDB). In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha-1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ? 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m-1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m-1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr-1 (0.7-2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditions after changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

  1. Progress and prospects of climate change impacts on hydrology in the arid region of northwest China.

    PubMed

    Chen, Yaning; Li, Zhi; Fan, Yuting; Wang, Huaijun; Deng, Haijun

    2015-05-01

    The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced "sharply" increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a "sharply" increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation. PMID:25682220

  2. Arid lands of the Southwest

    USGS Publications Warehouse

    Thorsteinson, Lyman

    2005-01-01

    When thinking about plants and animals that inhabit hot arid lands of the southwestern U.S., fish are easily overlooked by most people. However, these desert lands often contain isolated springs or cienegas (a Spanish term referring to permanently saturated 'seep wetlands') and streams supporting native fishes that occur no where else in the world. These aquatic remnants from the last Ice Age have survived for thousands of years due to an amazing ability to tolerate harsh environmental conditions, especially extremely high water temperatures, high salinities, and unpredictable water flows.

  3. Modeling analysis of ground water recharge potential on alluvial fans using limited data.

    PubMed

    Munévar, A; Mariño, M A

    1999-01-01

    A modeling approach is developed to evaluate the potential for artificial recharge on alluvial fans in the Salinas Valley, California, using limited data of soil texture, soil hydraulic properties, and interwell stratigraphy. Promising areas for surface recharge are identified and mapped on a broad-scale using soil surveys, geologic investigations, permeability tests, and seasonal ground water response to rainfall and runoff. Two-dimensional representations of the vadose zone at selected sites are then constructed from drillers'logs and soil material types are estimated. Next, hydraulic properties are assigned to each soil material type by comparing them to laboratory-tested cores of similar soils taken from one site. Finally, water flow through the vadose zone is modeled in two dimensions at seven sites using a transient, finite-difference, variably saturated flow model. Average infiltration rates range from 0.84 to 1.54 cm/hr and recharge efficiency, the percentage of infiltrated water that reaches the water table, varies from 51% to 79%. Infiltration rates and recharge efficiency are found to be relatively insensitive to recharge basin ponding depth due to the thickness of the vadose zones modeled (31 to 84 m). The impact of artificial recharge on the Salinas Valley ground water basin is investigated by simulating the regional ground water response to surface spreading and streamflow augmentation with a recently calibrated, finite-element, ground water-surface water model for the basin. It was determined that a combined approach of surface recharge and streamflow augmentation significantly reduces the state of ground water overdraft and, to a lesser extent, reduces the rate of sea water intrusion. PMID:19125917

  4. Precipitation and nitrogen interactions in arid ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arid and semi-arid ecosystems are among the most impoverished terrestrial systems in terms of water and nitrogen (N) availability. Productivity (NPP) is generally low, soil N pools are small and N loss through percolation is assumed to be negligible. Increased water availability can stimulate both N...

  5. Kinematic analysis of the ARID manipulator

    NASA Technical Reports Server (NTRS)

    Doty, Keith L

    1992-01-01

    The kinematic structure of the ARID manipulator lends itself to simple forward and inverse kinematics analysis. The purpose of this paper is to fully document and verify an existing analysis. The symbolic software package MATHEMATICA was used to produce and verify the equations presented here. In the analysis to follow, the standard Devenit-Hartenberg kinematic parameters of the ARID were employed.

  6. RIVERBANK FILTRATION EFFECTIVENESS IN AN ARID ENVIRONMENT

    EPA Science Inventory

    This experiment is a field test of bank filtration at a site where water level and salinity vary on an annual basis, as they do in many arid and semi-arid streams. No other studies of bank filtration have been performed in this kind of setting. Along the border with Mexico, shall...

  7. A model of channel response in disturbed alluvial channels

    USGS Publications Warehouse

    Simon, A.

    1989-01-01

    Dredging and straightening of alluvial channels between 1959 and 1978 in West Tennessee caused a series of morphologic changes along modified reaches and tributary streams. Degradation occurred for 10 to 15 years at sites upstream of the area of maximum disturbance and lowered bed-levels by as much as 6.1 m. Following degradation, reaches upstream of the area of maximum disturbance experienced a secondary aggradation phase in response to excessive incision and gradient reduction. -from Author

  8. Bahia Adair and vicinity, Sonora: modern siliciclastic-dominated arid macrotidal coastline

    SciTech Connect

    Lock, B.E.; Sinitiere, S.M.; Williams, L.J.

    1989-03-01

    The northwestern Sonoran coastline, in the vicinity of Bahia Adair, combines several important geologic features. The arid landward environments are dominated by the dunes of the Gran Desierto and the surrounding alluvial fans and ephemeral streams. The Colorado River, whose delta lies to the northwest, has been an important source of sediment until very recently. The high tidal energy of the region has profoundly influenced the distribution and geometries of coastal and shallow-marine sand bodies, and the active tectonic setting has also played a role. The Cerro Prieto splay of the San Andreas fault system has been responsible for local uplift and downwarp and resulting transgression and regression. The intertidal and supratidal zones are dominated by sand and constitute a sand-body type that has been seldom considered by petroleum explorationists or other students of ancient sand bodies, and the associated evaporites are rather different from those described from the superficially analogous Persian Gulf sabkhas.

  9. Alluvial plains and earthquake recurrence at the Coalinga anticline

    SciTech Connect

    Tucker, A.B. ); Donahue, D.J.; Jull, A.J.T ); Payen, L.A. ); Atwater, B.F.; Trumm, D.A.; Tinsley, J.C. III; Stein, R.S.

    1990-01-01

    Having approached 0.5 m during the May 2 earthquake, the uplift of Quaternary deposits on the Coalinga anticline may provide evidence of the average repeat time of similar earthquakes during the recent geologic past. Stein and King (1984) estimated the average late Quaternary repeat time to be 500 to 1,500 yr from the degree of folding in the upper Pliocene and Pleistocene Tulare Formation; in addition, they estimated the average Holocene repeat time to be at least 200 to 600 yr on the basis of an alluvial-plain profile near Los Gatos Creek, whose arroyo extends across the Coalinga anticline from the synclinal Pleasant Valley into the synclinal San Joaquin Valley. In this chapter, the authors estimate an average repeat time from the stratigraphy of Holocene alluvium exposed in the walls of that arroyo. Largely deposited overbank, this alluvium reveals the approximate configuration of former alluvial plains whose present configuration over the anticline should reflect the rate of anticlinal growth. Resulting constraints on the Holocene uplift rate, though made uncertain by possible differences in the initial configuration of the alluvial plains, suggest an average repeat time of at least 200 to 1,000 yr for major (M = 6-7) Coalinga-area earthquakes during the late Holocene.

  10. Uranium in framboidal pyrite from a naturally bioreduced alluvial sediment.

    PubMed

    Qafoku, Nikolla P; Kukkadapu, Ravi K; McKinley, James P; Arey, Bruce W; Kelly, Shelly D; Wang, Chongmin; Resch, Charles T; Long, Philip E

    2009-11-15

    Samples of a naturally bioreduced, U-contaminated alluvial sediment were characterized with various microscopic and spectroscopic techniques and wet chemical extraction methods. The objective was to investigate U association and interaction with minerals of the sediment. Bioreduced sediment comprises approximately 10% of an alluvial aquifer adjacent to the Colorado River, in Rifle, CO, that was the site of a former U milling operation. Past and ongoing research has demonstrated that bioreduced sediment is elevated in solid-associated U, total organic carbon, and acid-volatile sulfide, and depleted in bioavailable Fe(III) confirming that sulfate and Fe(III) reduction have occurred naturally in the sediment. SEM/EDS analyses demonstrated that framboidal pyrites (FeS(2)) of different sizes ( approximately 10-20 microm in diameter), and of various microcrystal morphology, degree of surface weathering, and internal porosity were abundant in the <53 microm fraction (silt + clay) of the sediment and absent in adjacent sediments that were not bioreduced. SEM-EMPA, XRF, EXAFS, and XANES measurements showed elevated U was present in framboidal pyrite as both U(VI) and U(IV). This result indicates that U may be sequestered in situ under conditions of microbially driven sulfate reduction and pyrite formation. Conversely, such pyrites in alluvial sediments provide a long-term source of U under conditions of slow oxidation, contributing to the persistence of U of some U plumes. These results may also help in developing remedial measures for U-contaminated aquifers. PMID:20028047

  11. Provenance and basin evolution, Zhada basin, southwestern Tibet

    NASA Astrophysics Data System (ADS)

    Saylor, J.; Decelles, P.; Gehrels, G.; Kapp, P.

    2007-12-01

    The Zhada basin is a late Miocene - Pliocene intermontane basin situated at high elevations in the Himalayan hinterland. The fluvial and lacustrine sediments of the Zhada formation are undeformed and sit in angular unconformity above the deformed Tethyan Sedimentary Sequence (TSS). The basin sits just south of the Indus suture in a structural position occupied elsewhere in the Himalayan orogen by some of the highest mountains on earth, including Everest. The occurrence of a basin at this location demands explanation. Currently, the Sutlej River flows parallel to the structural grain of the Himalaya, westward through the basin, towards the Leo Pargil (Qusum) range. Near the range front it takes a sharp southward turn, cuts across the structural grain of the Himalaya and out into the Gangetic foreland. Palaeocurrent indicators in the lower part of the Zhada formation show that the basin originated as a northwest flowing axial river. Palaeocurrent indicators are consistently northwest oriented, even to within to within 10 km of the Leo Pargil range front in the north-western end of the basin. This implies that at the onset of sedimentation in Zhada basin the Leo Pargil range was not a barrier as it is today. In the upper part of the Zhada formation, palaeocurrent indicators are generally directed towards the centre of the basin. In the central and southern portions of the basin this indicates a transition from an axial, northwest flowing river to prograding fluvial and alluvial fans. However, in the north-western part of the basin the change between lower and upper Zhada formation involves a complete drainage reversal. This change in palaeocurrent orientation is also reflected in the detrital zircon signal from basin sediments. Low in the Zhada formation the detrital zircon signal is dominated by zircons from the Kailash (Gangdese) batholith (or associated extrusives, see below). However, higher in the sections, a local source, either from the TSS or the core of the Leo Pargil range dominates the detrital zircon signal. Finally, there is a shift in the sandstone composition from unmetamorphosed sedimentary lithic fragments and extrusive felsic volcanic fragments in the lower part of the Zhada formation to metasedimentary and metaigneous fragments in the upper part of the Zhada formation. This is likely linked either to unroofing of the source terrain or a change to another source terrain. Based on the palaeocurrent and detrital zircon data, a change to another source terrain is favoured. This combination of evidence suggests that the Zhada basin evolved from a through-going fluvial plain to a dammed lake primarily due to uplift of the Leo Pargil range. This uplift would have dammed and ponded the river, and exposed higher grade metamorphic rocks at the surface for incorporation into Zhada formation sandstones. It also would have introduced a new source for detrital zircons. Uplift of the Leo Pargil range along a low angle normal fault would also have evacuated portions of the mid-crust, providing a mechanism for subsidence in the Zhada region. Lacustrine sedimentation would have coincided with progradation of marginal alluvial fans and would have continued until the basin was filled in to the level of a new spill point. At this time incision and re- establishment of the Sutlej River would have occurred.

  12. Hydrology of the Bayou Bartholomew alluvial aquifer-stream system, Arkansas

    USGS Publications Warehouse

    Broom, M.E.; Reed, J.E.

    1973-01-01

    The study area comprises about 3,200 square miles of the Mississippi Alluvial Plain in southeast Arkansas. About 90 percent of the area drains south to the Ouachita River in Louisiana. The alluvial aquifer and the streams are hydraulically connected and are studied as an aquifer-stream system. Bayou Bartholomew is a principal stream of the system. The aquifer is underlain by confining strata of the Jackson Group and Cockfield Formation. The mean annual surface-water yield of the area that drains to the Ouachita River basin is nearly 2 million acre-feet. Flood-control projects have significantly reduced flooding in the area. Basin boundaries and low-flow characteristics of streams have been altered as a result of the flood-control projects and streamflow diversion for irrigation. The direction of ground-water flow generally is southward. Bayou Bartholomew functions mostly as a drain for ground-water flow from the west and as a recharge source to the aquifer east of the bayou. As a result of navigation pools, the Arkansas River is mostly a steady-recharge source to the aquifer. Pumpage from the aquifer and streams increased from about 20,000 acre-feet in 1941 to 237,000 acre-feet in 1970. Estimates of flow, derived from analog analysis but lacking field verification, indicate that recharge to the aquifer in 1970 was about 161,000 acre-feet. About 70 percent of the recharge was by capture from streams as a result of ground-water pumpage. Discharge from the aquifer was about 233,000 acre-feet. About 80 percent of the discharge was through wells. Stream diversion in 1970 from capture and open channel, excluding capture from the Arkansas and Mississippi Rivers, was about 110,000 acre-feet. Return flow to streams from rice irrigation and fishponds was about 60,000 acre-feet. The chemical quality of streamflows is excellent for irrigation. Water from the aquifer generally ranges from permissible to excellent for irrigation. The use of water from the aquifer in the flood-plain area, exclusive of irrigation, is severely limited unless it is treated to remove the iron and reduce the hardness.

  13. Geomorphic Characterization of the FortyMile Wash Alluvial Fan, Nye County, Nevada, In Support of the Yucca Mountain Project

    SciTech Connect

    Cline; De Long; Pelletier; Harrington

    2005-09-06

    In the event of an unlikely volcanic eruption through the proposed high-level radioactive waste repository at Yucca Mountain, contaminated ash would be deposited in portions of the Fortymile Wash drainage basin and would subsequently be redistributed to the Fortymile Wash alluvial fan by fluvial processes. As part of an effort to quantify the transport of contaminated ash throughout the fluvial system, characterization of the Fortymile Wash alluvial fan is required, especially the spatial distribution of fluvial activity over time scales of repository operation, and the rates of radionuclide migration into different soils on the fan. The Fortymile Wash alluvial fan consists of extremely low relief terraces as old as 70 ka. By conducting soils-geomorphic mapping and correlating relative surface ages with available geochronology from the Fortymile Wash fan and adjacent piedmonts, we identified 4 distinct surfaces on the fan. Surface ages are used to predict the relative stability of different areas of the fan to fluvial activity. Pleistocene-aged surfaces are assumed to be fluvially inactive over the 10 kyr time scale, for example. Our mapping and correlation provides a map of the depozone for contaminated ash that takes into account long-term channel migration the time scales of repository operation, and it provides a geomorphic framework for predicting radionuclide dispersion rates into different soils across the fan. The standard model for vertical migration of radionuclides in soil is diffusion; therefore we used diffusion profiles derived from {sup 137}Cs fallout to determine infiltration rates on the various geomorphic surfaces. The results show a strong inverse correlation of the geomorphic surface age and diffusivity values inferred from the {sup 137}Cs profiles collected on the different surfaces of the fan.

  14. Alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes, and facies assemblages

    SciTech Connect

    Blair, T.C. ); McPherson, J.G. )

    1994-07-01

    Contrary to common contemporary usage, alluvial fans are a naturally unique phenomenon readily distinguishable from other sedimentary environments, including gravel-bed rivers, on the basis of morphology, hydraulic processes, sedimentologic processes, and facies assemblages. The piedmont setting of alluvial fans where the feeder channel of an upland drainage basin intersects the mountain front assures that catastrophic fluid gravity flows and sediment gravity flows, including sheetfloods, rock falls, rock slides, rock avalanches, and debris flows, are major constructional processes, regardless of climate. The unconfinement of these flows at the mountain front gives rise to the high-sloping, semiconical form that typifies fans. The plano-convex cross-profile geometry inherent in this form is the inverse of the toughlike cross-sectional form of river systems, and precludes the development of floodplains that characterize rivers. The relatively high slope of alluvial fans creates unique hydraulic conditions where passing fluid gravity flows attain high capacity, high competency, and upper flow regime, resulting in sheetfloods that deposit low-angle antidune or surface-parallel planar-stratified sequences. These waterlaid facies contrast with the typically lower-flow-regime thick-bedded, cross-bedded, and lenticular channel facies, and associated floodplain sequences, of rivers. The unconfinement of flows on fans causes a swift decrease in velocity, competency, and capacity as they attenuate, inducing rapid deposition that leads to the angular, poorly sorted textures and short radii typical of fans. This condition is markedly different than for rivers, where sediment gravity flows are rare and water flows remain confined by channel walls or spill into floodplains, and increase in depth downstream.

  15. New constraints on the uplift history of the western Andes, north Chile, using cosmogenic He-3 in alluvial boulders

    NASA Astrophysics Data System (ADS)

    Evenstar, Laura; Stuart, Finlay; Hartley, Adrian

    2014-05-01

    To constrain mechanisms responsible for mountain belt growth independent methods for determining accurately the rate and timing of surface uplift are needed. Within the Central Andes paleoelevation proxies are afflicted by either large uncertainties or reliance on assumptions about past climate-elevation histories (Barnes and Ehmer. 2009). This leads to paleoelevation data being unable to distinguish between the two main uplift models of the Andes; gradual uplift of the Andes from the Late Eocene due to crustal shortening/thickening, and rapid uplift in the Late Miocene due to large-scale mantle delamination (Barnes and Ehmer. 2009). Here we present a new paleoelevation tool based on the varying production rate of in situ cosmogenic isotopes with elevation. It can constrain surface uplift histories independently of paleoclimatic fluctuations, making it potentially more accurate than previous methods. Within the Atacama Desert Northern Chile, a stable arid-hyperarid climate has persisted over the last 23 Ma (Dunai et al. 2005). This has lead to exceptionally low erosion rates and high cosmogenic nuclide concentrations within alluvial boulders overlying the Pacific Planation Surface (PPS). In the Aroma Quebrada region, the PPS can be constrained as forming post 13.4 Ma, using underlying volcanics (Evenstar 2007). Alluvial boulders that lie on this PPS have high concentrations of cosmogenic He-3 that suggest deposition soon after surface formation. Comparing concentrations of cosmogenic 3He in the boulders to those calculated for varying uplift histories the timing of the uplift of the western margin of the Andes can be constrained. The models require the Pacific Planation Surface to reach at least 2/3 of its current elevation by 13.4 Ma. These results are not consistent with rapid uplift of the Andes due to mantle delamination in the Late Miocene but support progressive shortening and thickening of continental crust initiating in the Early Miocene or earlier.

  16. Tracing the lateral movement of sediments through a shrubland environment using fallout radionuclides, Jornada Basin, Southern New Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Semi-arid grassland and savanna communities in many parts of the world have been displaced by woody shrubs. In the Jornada Basin of southern New Mexico, the displacement of perennial grasslands is well documented beginning in 1858. As shrubs invade semi-arid perennial grasslands, the length, number,...

  17. Lateral groundwater inflows into alluvial aquifers of main alpine valleys

    NASA Astrophysics Data System (ADS)

    Burger, Ulrich

    2015-04-01

    In alpine regions the topography is mainly characterised by deep incised valleys, mountain slopes and ridges. Usually the main valleys contain aquifers in alluvial soft rock. Lateral these aquifers are confined by mountainous hard rock slopes covered by heterogeneous sediments with different thickness. The slopes can be incised by lateral valleys. Numerical models for the main alluvial aquifers ask for lateral hydrogeological boundaries. Usually no flow boundaries or Constant head Boundaries are used, even if the lateral inflows to the main aquifers are rarely known. In this example a data set for a detailed investigated and monitored area is studied to give an answer on the location and the quantification of these lateral subsurface inflows. The study area is a typical main alpine valley with a thick alluvial aquifer (appr. 120m thick), lateral confined by granite, covered at the base of the steep slopes by quaternary sediments (Burger at al. 2012). The study consists of several steps 1.) Analytical calculation of the inflows on the base of investigated and monitored 2d profiles along fault zones (Perello et al 2013) which pinch out in the main valley 2.) Analytical models along typical W-dipping slopes with monitored slope springs 3.) Evaluating temperature and electrical conductivity profiles measured in approx. 30 groundwater wells in the alluvial aquifers and along the slopes to locate main lateral subsurface inflows 4.) Output of a regional model used for the hydrogeological back analyses of the excavation of a tunnel (Baietto et al. 2014) 5.) Output of a local numerical model calibrated with a monitoring dataset and results of a pumping test of big scale (450l/s for 10days) Results of these analyses are shown to locate and quantify the lateral groundwater inflows in the main alluvial aquifer. References Baietto A., Burger U., Perello P. (2014): Hydrogeological modelling applications in tunnel excavations: examples from tunnel excavations in granitic rocks; congress of IAEG, Engineering Geology for Society and Territory, Torino Burger U., San Nicoló L. Bösel D. und Perello P. (2012): Hydrogeologische Modelle - Hilfsmittel für die Planung am Beispiel des Brenner Basistunnel, Beiträge zur Beiträge zur COGeo 2011, Salzburg COGEO Perello P., Baietto A., Burger U., Skuk S. (2013): Excavation of the Aica-Mules pilot tunnel for the Brenner base tunnel: information gained on water inflows in tunnels in granitic massifs, Rock Mechanics and Rock Engineering, DOI 10.1007/s00603-013-0480-x

  18. Evaluating the complementary relationship for estimating evapotranspiration from arid shrublands

    NASA Astrophysics Data System (ADS)

    Huntington, J. L.; Szilagyi, J.; Tyler, S. W.; Pohll, G. M.

    2011-05-01

    Given increasing demands on finite water supplies, accurate estimates of evapotranspiration (LE) from arid shrublands of the Southwestern United States are needed to develop or refine basin water budgets. In this work, a novel approach to estimating the equilibrium (or wet environment) surface temperature (Te) and LE from regionally extensive phreatophyte shrublands is tested using complementary theory and micrometeorological data collected from five eddy correlation stations located in eastern Nevada. A symmetric complementary relationship between the potential LE (LEp) and actual LE is extremely attractive because it is based on general feedback mechanisms where detailed knowledge of the complex processes and interactions between soil, vegetation, and the near-surface boundary layer can be avoided. Analysis of computed LEp and eddy correlation-derived LE indicates that there is unequivocal evidence of a complementary relationship between LEp and LE, where the measured and normalized complementary relationship is symmetric when Te is utilized to compute the wet environment LE (LEw). Application of a modified Brutsaert and Stricker advection-aridity (AA) model, where Te is utilized to compute LEw as opposed to the measured air temperature, indicates an improvement in prediction accuracy over the standard Brutsaert and Stricker AA model. Monthly and annual predictions of LE using the modified AA model are within the uncertainty of the measurement accuracy, making the application of this approach potentially useful for estimating regional LE in arid shrubland environments. Our observational evidence supports the idea of a symmetric complementary relationship yielding an approach with standard parameters, making it simple to apply with satisfactory accuracy. To our knowledge, this work presents the first application and evaluation of the complementary relationship in phreatophyte shrublands while utilizing the Te with comparisons to actual LE via flux measurements.

  19. Semi-Arid Landscapes: The Canary in the Climate-Change Coalmine (Invited)

    NASA Astrophysics Data System (ADS)

    Pierce, J. L.; Poulos, M. J.

    2013-12-01

    The balance between precipitation as a driving force of sediment transport (via hillslope erosional processes) or a resisting force (via increases in vegetation cover) is reflected by the landforms and denudation rates in semi-arid landscapes. While exact values vary, studies examining the relationship between land surface lowering and mean annual precipitation show a ';sweet spot' of peak denudation rates for semi-arid landscapes receiving ~300-500 mm precipitation/year. Ongoing and future climate change necessitates the investigation of how landscapes may respond as they move towards or away from this erosional threshold; semi-arid landscapes on the edge of ecohydrologic thresholds (e.g. treelines) may experience dramatic environmental changes as ongoing and future climate change alters ecosystems. Semi-arid landscapes are the equivalent to canaries in a coal-mine, and studying them advances understanding of how other sensitive landscapes may respond to climate change. Landforms, however, are a product of thousands to millions of years of climatic forcing. Direct measurement of both short and long-term erosion rates is complicated, and observations of modern erosional processes may not reflect the past. Over 10 years of environmental data collected in the heavily instrumented Dry Creek Experimental Watershed (DCEW) outside Boise, Idaho facilitates 2nd order analysis of climate-driven environmental variability across a large area (27 km2). Multi-scaled analyses relate runoff production from pedons to catchments, and erosion rates and processes from hillslopes to landforms, while prior mapping results (Poulos et al, 2012) allow application of results to similar semi-arid montane landscapes. Preliminary data reveal intriguing, but counterintuitive, feedbacks among soil properties, hillslope hydrology, ecology, and drainage development. Despite steeper slope angles, north-facing slopes have thicker soils than south-facing slopes, suggesting slower erosion rates. This conflicts with theories of hillslope processes which predict that erosion rates increase and soil thicknesses decrease with increasing slope angles. Could future increases in temperatures and decreased vegetation push north-facing slopes beyond a geomorphic tipping point, where their soils and drainages erode like south-facing slopes? Also, shallower soils and reduced plant cover on south-facing slopes appear to limit soil water storage and evapotranspiration, culminating in increased runoff and streamflow from these relatively drier ecosystems. What impact do these pedon- and hillslope-scale differences in runoff have on catchment-scale drainage erosion, incision and expansion? Finally, while landforms and erosion rates reflect, to some degree, the annual to centennial-scale climate conditions and precipitation events, episodic events such as wildfires exert a major control on erosion rates. Alluvial fans act as natural (albeit a bit leaky) sediment traps for hillslope erosion from 1st order drainage systems, while charcoal fragments in alluvial fan stratigraphic sequences provide both evidence of fire, and (through 14C dating) a means to estimate erosion rates. Ongoing fire studies in the DCEW, combined with surveys of alluvial fan sediment volumes, will reveal 1) the contribution of fire events to overall erosion rates, 2) variability in erosion rates between north and south facing slopes and 3) changes in Holocene fire activity with changes in climate.

  20. Water and the arid lands of the western United States

    SciTech Connect

    El-Ashry, M.T.; Gibbons, D.C.

    1988-01-01

    The United States is water-rich, but conflicts over water development and use are increasing. Today, economic scarcity - not absolute physical scarcity - is the key issue in many places. In the arid American West, traditionally over 90 percent of the water consumed has been used to irrigate agriculture. But as cities grow and the states's economies diversify, municipal, commercial, and industrial uses exert more pressure. At the same time, groundwater mining and water quality degradation are becoming commonplace. The challenge is to increase productivity while equitably distributing the costs and benefits of water use. This book includes three case studies that cover primarily agricultural areas (the Central Valley of California, the High Plains of Texas, and the upper Colorado River basin) and three on the problems of metropolitan areas (Denver, Tucson, and the southern California megalopolis). The authors also identify policies that could help the West sustain economic growth without destroying or undervaluing its natural resources.

  1. Salinization in semi-arid irrigated agricultural regions

    NASA Astrophysics Data System (ADS)

    Ale, S.

    2014-12-01

    Large-scale introduction of canal irrigation systems across the semi-arid regions of the World has disturbed hydrologic equilibrium of many groundwater basins. This has resulted in rise of groundwater levels followed by degradation of soils through water logging and secondary saltbuild-up in many canal commands, and caused millions of hectares of irrigated agricultural land to go out of production. On the other hand, extensive pumping of groundwater for irrigation in some freshwater aquifers has lowered hydraulic heads and induced cross-formational flow from underlying highly mineralized older formations, which led to groundwater mixing between the formations and rise insalinity levels in the overlying fresh water aquifers over time. Some examples related to irrigation induced soil and groundwater salinization from India and the United States will be presented. Potential causes of salinization and possible solutions will be discussed.

  2. Evaluating process domains in small arid granitic watersheds: Case study of Pima Wash, South Mountains, Sonoran Desert, USA

    NASA Astrophysics Data System (ADS)

    Seong, Yeong Bae; Larson, Phillip H.; Dorn, Ronald I.; Yu, Byung Yong

    2016-02-01

    This paper provides support for the concept of geomorphic process domains developed by Montgomery (1999) by linking geomorphic processes to ecological variations seen in the Pima arid granitic watershed of the Sonoran Desert, Phoenix, Arizona. Closer joint spacing shows a statistically significant correlation with lower percentages of mineral grain attachment as measured by digital image processing of backscattered electron microscope imagery. Lower mineral grain attachment leads to more frequent spalling of rock surfaces, as measured by varnish microlamination (VML) ages of the last spalling event. In contrast, more distant joint spacing leads to in situ 10Be erosion rates of 3.4-8.5 mm/ka and the emergence of low domes and kopje granitic landforms; these low domes also serve as knickpoints along ephemeral washes. Distant jointing thus plays a key role in generating the bare bedrock surfaces that funnel limited precipitation to bedrock margins - enhancing the canopy cover of perennial plants next to the bare bedrock. Joint-influenced geomorphic processes at Pima Wash generate four distinct process domains: (PD1) armored drainage divides; (PD2) slopes with different granite landforms; (PD3) mid- and upper basin channels that mix knickzones, strath floodplains, and sandy alluvial sections; and (PD4) the main ephemeral channel transitioning to the piedmont. Distant jointing promotes bedrock exposure and rock armoring along drainage divides in PD1 that then concentrates runoff and promotes perennial plant growth. More distant joint spacing on slopes in PD2 promotes exposure of granitic bedrock forms that shed overland flow to their margin and promotes flora and fauna growths along the margins of low granitic domes and kopjes. Similarly, wider joint spacing along ephemeral washes in PD3 leads to knickpoints, which in turn act to concentrate moisture immediately downstream. The stream terraces in PD4 influence the ecology through xeric desert pavements on terrace treads and roofs for coyotes (Canis latrans) and gray fox (Urocyon Cinereoargenteus) dens on terrace scarps via stage 3 pedogenic carbonate. These four process domains occur in six other randomly selected granitic watersheds with drainage areas < 5 km2 in the Mojave and Sonoran Deserts. Results on rates of geomorphic processes in the Pima Wash watershed provide new insight in the desert geomorphology of small granitic watersheds. Catchment-wide denudation rates (CWDRs) recorded by 10Be sampled along the main ephemeral wash vary between 15 and 23 mm/ka and do not appear to be influenced by knickpoint or knickzone occurrence; instead slightly lower CWDRs appear to be associated with sediment contributions by subbasins with more abundance of bare bedrock forms. Resampling for CWDR after a 500-year flood event from hurricane moisture at two sites along the main ephemeral channel revealed no detectable changes; this finding confirms the average representativeness of CWDR as a long-term denudation proxy and also means that sediment transport on these arid granitic hillslopes must be incremental and without rapid crest to wash transport. The first reported measurements of incision rates into a small granitic Sonoran Desert watershed, using 10Be and VML, reveal rates on the order of 70-180 mm/ka in the lower quarter of Pima Wash for the last 60 ka - producing a narrow and deep trench. As this base-level fall propagates upstream, erosion focuses on weaker material with higher joint densities; this facilitates the emergence of domes and kopje landforms with more widely spaced jointing.

  3. Stratigraphy and stable isotope results from an Eocene-Miocene section of the western Qaidam Basin, NW China

    NASA Astrophysics Data System (ADS)

    Li, L.; Garzione, C. N.; Pullen, A.; Chang, H.; Molnar, P. H.

    2012-12-01

    The climate of central Asia has changed significantly throughout the Cenozoic, with surface uplift of the Himalaya and Tibetan Plateau cited as the primary cause of the change. However, the timing and mechanisms of plateau uplift, especially the northern plateau, is still unclear. Sedimentary basin deposits and their stable isotopic composition record both paleo-environment and paleoclimate information and thus can be used to study the climate evolution and ultimately-the surface uplift history. The Qaidam Basin, in the northern part of the Tibetan Plateau, deposited thick fluviolacustrine sediments from Eocene to Pleistocene time. Here, we report a newly documented 4440 m long sedimentary section near Huatugou town in the western Qaidam Basin, and preliminary O and C stable isotope results from sedimentary carbonates. The section includes four formations. Xiaganchaigou Formation (XGCG Fm), with a late Eocene age, is dominated by alluvial to fluvial conglomerates, sandstones and sandy mudstones in the lower part, and siltstones, mudstones with gypsum of lacustrine origin in the upper part. The Oligocene Shangganchaigou Formation (SGCG Fm) and early to middle Miocene Xiayoushashan Formation (XYSS Fm) both consist mainly of lacustrine mudstones, siltstones, sandstones, intercalated with marls, limestones and minor conglomerates. The late Miocene Shangyoushashan Formation (SYSS Fm, the lower part) is dominated by alluvial to delta-front conglomerates, gravelly sandstones and siltstones; paleosols with root traces are also common in this formation. Between 232 and 1196 m (XGCG Fm), both the ?18O (VPDB) and ?13C (VPDB) values of marls show large variability between -3.3 and -8.9‰ and between 0.7 and -2.7‰, respectively. Between 1196 and 2524 m (SGCG Fm), the ?18O values of marls and limestones show a more narrow range of lower values between -7.0 and -8.6‰, and the ?13C values decrease to between -1.5 and -4.9‰. We speculate that the large variability in XGCG Fm resulted from late Eocene climate cyclicity, followed by decreasing ? values related to global cooling during the Eocene-Oligocene transitions and cooling associated with the horizontal translation of the Basin to higher latitudes. From 2500 to 3500 m (XYSS Fm), there is a more pronounced decrease in the ?18O values of paleosols and carbonate cements to between -8.2 and -10.0‰, but their ?13C values show large variations between -0.6 and -6.8‰. A plausible explanation for these changes is localized climate perturbations associated with the growth of surrounding mountain ranges. At the top of the section, between 3500 and 4400 m (XYSS and SYSS Fm), both the ?18O and ?13C values of paleosols and carbonate cements show a positive shift by 1 to 2‰. This positive shift is interpreted as the result of mid-Miocene aridification, a regional climatic change event that was also documented in Tarim Basin, eastern Qaidam Basin, and in the northeastern Tibetan Plateau. Extreme aridity that is comparable to present day is not recorded in the Huatuguo section, most likely because these deposits predate the Plio-Pleistocene time period when modern conditions were established.

  4. ARID relative calibration experimental data and analysis

    NASA Technical Reports Server (NTRS)

    Doty, Keith L

    1992-01-01

    Several experiments measure the orientation error of the ARID end-frame as well as linear displacements in the Orbiter's y- and z-axes. In each experiment the position of the ARID on the trolley is fixed and the manipulator extends and retracts along the Orbiter's y-axis. A sensor platform consisting of four sonars arranged in a '+' pattern measures the platform pitch about the Orbiter's y-axis (angle b) and yaw about the Orbiter's x-axis (angle alpha). Corroborating measurements of the yaw error were performed using a carpenter's level to keep the platform perpendicular to the gravity vector at each ARID pose being measured.

  5. Attributes of an alluvial river and their relation to water policy and management

    PubMed Central

    Trush, William J.; McBain, Scott M.; Leopold, Luna B.

    2000-01-01

    Rivers around the world are being regulated by dams to accommodate the needs of a rapidly growing global population. These regulatory efforts usually oppose the natural tendency of rivers to flood, move sediment, and migrate. Although an economic benefit, river regulation has come at unforeseen and unevaluated cumulative ecological costs. Historic and contemporary approaches to remedy environmental losses have largely ignored hydrologic, geomorphic, and biotic processes that form and maintain healthy alluvial river ecosystems. Several commonly known concepts that govern how alluvial channels work have been compiled into a set of “attributes” for alluvial river integrity. These attributes provide a minimum checklist of critical geomorphic and ecological processes derived from field observation and experimentation, a set of hypotheses to chart and evaluate strategies for restoring and preserving alluvial river ecosystems. They can guide how to (i) restore alluvial processes below an existing dam without necessarily resorting to extreme measures such as demolishing one, and (ii) preserve alluvial river integrity below proposed dams. Once altered by dam construction, a regulated alluvial river will never function as before. But a scaled-down morphology could retain much of a river's original integrity if key processes addressed in the attributes are explicitly provided. Although such a restoration strategy is an experiment, it may be the most practical solution for recovering regulated alluvial river ecosystems and the species that inhabit them. Preservation or restoration of the alluvial river attributes is a logical policy direction for river management in the future. PMID:11050220

  6. New interpretation of the role of water balance in an extended Budyko hypothesis in arid regions

    NASA Astrophysics Data System (ADS)

    Du, C.; Sun, F.; Yu, J.; Liu, X.; Chen, Y.

    2016-01-01

    The Budyko hypothesis (BH) is an effective approach to investigating long-term water balance at large basin scale under steady state. The assumption of steady state prevents applications of the BH to basins, which is unclosed, or with significant variations in root zone water storage, i.e., under unsteady state, such as in extremely arid regions. In this study, we choose the Heihe River basin (HRB) in China, an extremely arid inland basin, as the study area. We firstly use a calibrated and then validated monthly water balance model, i.e., the abcd model, to quantitatively determine annual and monthly variations of water balance for the sub-basins and the whole catchment of the HRB, and find that the roles of root zone water storage change and that of inflow from upper sub-basins in monthly water balance are significant. With the recognition of the inflow water from other regions and the root zone water storage change as additional possible water sources to evapotranspiration in unclosed basins, we further define the equivalent precipitation (Pe) to include local precipitation, inflow water and root zone water storage change as the water supply in the Budyko framework. With the newly defined water supply, the Budyko curve can successfully describe the relationship between the evapotranspiration ratio and the aridity index at both annual and monthly timescales, whilst it fails when only the local precipitation being considered. Adding to that, we develop a new Fu-type Budyko equation with two non-dimensional parameters (ω and λ) based on the deviation of Fu's equation. Over the annual timescale, the new Fu-type Budyko equation developed here has more or less identical performance to Fu's original equation for the sub-basins and the whole catchment. However, over the monthly timescale, due to large seasonality of root zone water storage and inflow water, the new Fu-type Budyko equation generally performs better than Fu's original equation. The new Fu-type Budyko equation (ω and λ) developed here enables one to apply the BH to interpret regional water balance over extremely dry environments under unsteady state (e.g., unclosed basins or sub-annual timescales).

  7. New interpretation of the role of water balance in an extended Budyko hypothesis in arid regions

    NASA Astrophysics Data System (ADS)

    Du, C.; Sun, F.; Yu, J.; Liu, X.; Chen, Y.

    2015-10-01

    The Budyko hypothesis (BH) is an effective approach to investigating long-term water balance at large basin scale under steady state. The assumption of steady state prevents applications of the BH to basins, which is unclosed, or with significant variations in soil water storage, i.e., under unsteady state, such as in extremely arid regions. In this study, we choose the Heihe River Basin (HRB) in China, an extremely arid inland basin, as the study area. We firstly use a calibrated and then validated monthly water balance model, i.e., the abcd model to quantitatively determine annual and monthly variations of water balance for the sub-basins and the whole catchment of the HRB and find that the role of soil water storage change and that of inflow from upper sub-basins in monthly water balance are significant. With the recognition of the inflow water from other regions and the soil water storage change as additional possible water sources to evapotranspiration in unclosed basins, we further define the equivalent precipitation (Pe) to include local precipitation, inflow water and soil water storage change as the water supply in the Budyko framework. With the newly defined water supply, the Budyko curve can successfully describe the relationship between the evapotranspiration ratio and the aridity index at both annual and monthly timescales, whilst it fails when only the local precipitation being considered. Adding to that, we develop a new Fu-type Budyko equation with two non-dimensional parameters (? and ?) based on the deviation of Fu's equation. Over the annual time scale, the new Fu-type Budyko equation developed here has more or less identical performance to Fu's original equation for the sub-basins and the whole catchment. However, over the monthly time scale, due to large seasonality of soil water storage and inflow, the new Fu-type Budyko equation generally performs better than Fu's original equation. The new Fu-type Budyko equation (? and ?) developed here enables one to apply the BH to interpret regional water balance over extremely dry environments under unsteady state (e.g., unclosed basins or sub-annual timescales).

  8. Desert Pavement Process and Form: Modes and Scales of Landscape Stability and Instability in Arid Regions

    NASA Astrophysics Data System (ADS)

    Wells, Stephen G.; McFadden, Leslie D.; McDonald, Eric V.; Eppes, Martha C.; Young, Michael H.; Wood, Yvonne A.

    2014-05-01

    Desert pavements are recognized in arid landscapes around the world, developing via diminution of constructional/depositional landform relief and creating a 1-2 stone thick armor over a "stone free" layer. Surface exposure dating demonstrates that clasts forming the desert pavements are maintained at the land surface over hundreds of thousands of years, as aeolian fines are deposited on the land surface, transported into the underlying parent material and incorporated into accretionary soil horizons (e.g., the stone free or vesicular [Av] horizon). This surface armor provides long-term stability over extensive regions of the landscape. Over shorter time periods and at the landform-element scale, dynamic surficial processes (i.e., weathering, runoff) continue to modify the pavement form. Clast size reduction in comparison to underlying parent material, along with armoring and packing of clasts in pavements contribute to their persistence, and studies of crack orientations in pavement clasts indicate physical weathering and diminution of particle size are driven by diurnal solar insolation. Over geologic time, cracks form and propagate from tensile stresses related to temporal and spatial gradients in temperature that evolve and rotate in alignment with the sun's rays. Observed multimodal nature of crack orientations appear related to seasonally varying, latitude-dependent temperature fields resulting from solar angle and weather conditions. Surface properties and their underlying soil profiles vary across pavement surfaces, forming a landscape mosaic and controlling surface hydrology, ecosystem function and the ultimate life-cycle of arid landscapes. In areas of well-developed pavements, surface infiltration and soluble salt concentrations indicate that saturated hydraulic conductivity of Av horizons decline on progressively older alluvial fan surfaces. Field observations and measurements from well-developed desert pavement surfaces landforms also yield significantly lower infiltration rates, enhanced rates of overland flow characterized by high water:sediment ratios and reduced production of desert ecosystems. Consequently, regionally extensive pavement and significantly decreased infiltration over geologic time have resulted in widespread overland flow, elaborate drainage networks on alluvial and eolian-mantled bedrock landscapes, and channel incision and regional dissection of the pavement-mantled landforms. However, these once stable landscapes become progressively unstable with time, serving as sediment source areas for younger alluvial deposits (i.e., geologic life-cycle). Thus, regional dissection (instability) of these desert landscapes can be influenced by the intrinsic properties of pavement-mantled landscapes and not necessarily to external forces of climate change and tectonics.

  9. Controls of the water and sediment fluxes on alluvial fans morphology: theory and experiments

    NASA Astrophysics Data System (ADS)

    Guerit, Laure; Delorme, Pauline; Métivier, François; Lajeunesse, Eric; Devauchelle, Olivier; Barrier, Laurie

    2015-04-01

    Alluvial fans are major sedimentary bodies that make the transition between the reliefs in erosion and the sedimentary basins, where deposition occurs. Understanding their dynamics of formation and evolution is a great problem of sediment transport, which leads to a better understanding of the control exerted by the water and sediment fluxes on the fan morphology. At the cost of several simplifications, we propose a totally predictive model for one-dimensional fans composed by one grain size and built under laminar flow. In this simplified context, it is possible to propose a unique relationship between the water flux, the sediment flux, the grain size and the slope of the fan. The theory is validated by one-dimension experiments, performed with glass beads and glycerine: the fan grows quasi-statically and maintains its slope just above the threshold for sediment transport. In addition, at leading order, the sediment discharge only controls the velocity at which the fan grows. These main predictions are then successfully tested in two-dimensional experiments.

  10. Using major ions and ?15N-NO3(-) to identify nitrate sources and fate in an alluvial aquifer of the Baiyangdian lake watershed, North China Plain.

    PubMed

    Wang, Shiqin; Tang, Changyuan; Song, Xianfang; Yuan, Ruiqiang; Wang, Qinxue; Zhang, Yinghua

    2013-07-01

    In semi-arid regions, most human activities occur in alluvial fan areas; however, NO3(-) pollution has greatly threatened the shallow groundwater quality. In this paper, ?(15)N-NO3(-) and multi-tracers were used to identify the origin and fate of NO3(-) in groundwater of the Baiyangdian lake watershed, North China Plain. The investigation was conducted in two typical regions: one is the agricultural area located in the upstream of the watershed and another is the region influenced by urban wastewater in the downstream of the watershed. Results indicate that the high NO3(-) concentrations of the upstream shallow groundwater were sourced from fertilizer and manure or sewage leakage, whilst the mixture and denitrification caused the decrease in the NO3(-) concentration along the flow path of the groundwater. In the downstream, industrial and domestic effluent has a great impact on groundwater quality. The contaminated rivers contributed from 45% to 76% of the total recharge to the groundwater within a distance of 40 m from the river. The mixture fraction of the wastewater declined with the increasing distance away from the river. However, groundwater with NO3(-) concentrations larger than 20 mg l(-1) was only distributed in areas near to the polluted river or the sewage irrigation area. It is revealed that the frontier and depression regions of an alluvial fan in a lake watershed with abundant organics, silt and clay sediments have suitable conditions for denitrification in the downstream. PMID:23743546

  11. Alluvial Diamond Resource Potential and Production Capacity Assessment of Ghana

    USGS Publications Warehouse

    Chirico, Peter G.; Malpeli, Katherine C.; Anum, Solomon; Phillips, Emily C.

    2010-01-01

    In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by both diamond-producing and diamond-importing countries. Over 70 countries were included as members at the end of 2007. To prevent trade in 'conflict' diamonds while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was to assess the alluvial diamond resource endowment and current production capacity of the alluvial diamond-mining sector in Ghana. A modified volume and grade methodology was used to estimate the remaining diamond reserves within the Birim and Bonsa diamond fields. The production capacity of the sector was estimated using a formulaic expression of the number of workers reported in the sector, their productivity, and the average grade of deposits mined. This study estimates that there are approximately 91,600,000 carats of alluvial diamonds remaining in both the Birim and Bonsa diamond fields: 89,000,000 carats in the Birim and 2,600,000 carats in the Bonsa. Production capacity is calculated to be 765,000 carats per year, based on the formula used and available data on the number of workers and worker productivity. Annual production is highly dependent on the international diamond market and prices, the numbers of seasonal workers actively mining in the sector, and environmental conditions, which influence seasonal farming.

  12. Thermal tracer tests for characterizing a shallow alluvial aquifer

    NASA Astrophysics Data System (ADS)

    Wildemeersch, Samuel; Klepikova, Maria; Jamin, Pierre; Orban, Philippe; Hermans, Thomas; Brouyère, Serge; Dassargues, Alain

    2014-05-01

    Using heat as an active tracer in different types of aquifers is a topic of increasing interest [e.g. Vandenbohede et al.; 2008, Wagner et al., 2013; Read et al., 2013]. In this study, we investigate the potential interest of coupling heat and solute tracer tests for characterization of a shallow alluvial aquifer. A thermal tracer test was conducted in the alluvial aquifer of the Meuse River, Belgium. The tracing experiment consisted in simultaneously injecting heated water and a dye tracer in a piezometer and monitoring the evolution of groundwater temperature and tracer concentration in the recovery well and in nine monitoring wells located according to three transects with regards to the main groundwater flow direction. The breakthrough curves measured in the recovery well showed that heat transfer in the alluvial aquifer is slower and more dispersive than solute transport. Recovery is very low for heat while in the same time it is measured as relatively high for the solute tracer. This is due to the fact that heat diffusion is larger than molecular diffusion, implying that exchange between groundwater and the porous medium matrix is far more significant for heat than for solute tracers. Temperature and concentrations in the recovery well are then used for estimating the specific heat capacity with the energy balance approach and the estimated value is found to be consistent with those found in the literature. Temperature breakthrough curves in other piezometers are contrasted with what would be expected in an ideal layered aquifer. They reveal strongly unequal lateral and vertical components of the transport mechanisms. By means of a numerical heat transport model, we provide a preliminary interpretation of these temperature breakthrough curves. Furthermore, these data could be included in the calibration of a complex heat transfer model for estimating the entire set of heat transfer parameters and their spatial distribution by inverse modeling.

  13. Deposition and early hydrologic evolution of Westwater Canyon wet alluvial-fan system

    SciTech Connect

    Galloway, W.E.

    1980-01-01

    The Westwater Canyon Member is one of several large, low-gradient alluvial fans that compose the Morrison Formation in the Four Corners area. Morrison fans were deposited by major laterally migrating streams entering a broad basin bounded by highlands to the west and south. The Westwater Canyon sand framework consists of a downfan succession of 1) proximal braided channel, 2) straight bed-load channel, 3) sinuous mixed-load channel, and 4) distributary mixed-load-channel sand bodies. Regional sand distribution and facies patterns are highly digitate and radiate from a point source located northwest of Gallup, New Mexico. Early ground-water flow evolution within the Westwater Canyon fan aquifer system can be inferred by analogy with Quaternary wet-fan deposits and by the interpreted paragenetic sequence of diagenetic features present. Syndepositional flow was controlled by the downfan hydrodynamic gradient and the high horizontal and vertical transmissivity of the sand-rich fan aquifer. Dissolution and transport of soluble humate would be likely in earliest ground water, which was abundant, fresh, and slightly alkaline. With increasing confinement of the aquifer below less permeable tuffaceous Brushy Basin deposits and release of soluble constituents from volcanic ash, flow patterns stabilized, and relatively more saline, uranium-rich ground water permeated the aquifer. Uranium mineralization occurred during this early postdepositional, semiconfined flow phase. Development of overlying Dakota swamps suggests a shallow water table indicative of regional dischare or stagnation. In either event, only limited downward flux of acidic water is recorded by local, bleached, kaolinized zones where the Westwater Canyon directly underlies the Dakota swamps. Subsequent ground-water flow phases have further obscured primary alteration patterns and caused local oxidation and redistribution of uranium.

  14. Quaternary Faults and Basin-fill Sediments of the Las Vegas Basin, Southern Nevada

    NASA Astrophysics Data System (ADS)

    Taylor, W. J.; Fossett, E.; Luke, B.; Snelson, C.; Rasmussen, T.; McCallen, D.; Rodgers, A.; Louie, J.

    2003-12-01

    The N-S elongated extensional Las Vegas basin, southern Nevada, contains 100's of meters of Cenozoic basin-fill sediments that are cut by several Quaternary (Q) faults. These faults define or influence the basin geometry. The basin is generally an asymmetrical half graben defined by the W-dipping, Q Frenchman Mountain fault (FMF) along its E side and a series of smaller offset E-dipping faults to the W. The N terminus of the basin is controlled by the Las Vegas Valley shear zone, along which the majority of the offset occurred prior to the Q. Here, we asses the influence of the Q faults on the distribution of the sedimentary units. Well, exposure, seismic reflection and seismic refraction data show that sedimentary units of different grain sizes or seismic velocity dominate different parts of the basin. Sections dominated by coarse clastic deposits occupy a narrow area along the E side of the basin. Coarse clastic sediments are mixed with finer grained sediments in a broader area along the W side of the basin. Based on provenance and alluvial fan distribution, the coarse deposits along the E side of the basin appear to be trapped in close proximity to the W-dipping FMF. The coarse-grained deposits along the opposite, W side of the basin, are sourced from the nearby Spring Mountains. Because of the structural asymmetry of the basin, these sediments traveled farther from their source area than those on the E side. Some of these E-dipping faults influence the depth to Paleozoic bedrock and some faults form small sub-basins filled with finer grained sediments. Along a WNW trend near the center of the basin and near the present-day Las Vegas Wash, a change in the grain size distribution occurs up stratgraphic section: continuous clay layers are less common and coarse-grained deposits are more common. This difference may reflect a change from internal drainage early in the basin history to external drainage through the Las Vegas Wash in the latter history of the basin-fill sedimentation. This interpretation implies that the FMF was breached by a wash connected to the Colorado River drainage system during basin development. The basin fill deposits suggest an early history of alluvial fan dominated deposits showing internal drainage. That depositional system was followed by E- and W-sloping alluvial fans cut by a NW-trending external dra