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Sample records for active gully beds

  1. Soil-plant system development 9 to 136 years after marly gully beds rehabilitation (French Southern Alps)

    NASA Astrophysics Data System (ADS)

    Erktan, Amandine; Cohen, Marianne; Zerouali, Laila; Poulenard, Jérôme; Cécillon, Lauric; Rey, Freddy

    2013-04-01

    Marly badlands, showing active eroded gullies and low soil fertility, are found in the French Southern Alps for around 250 years. Negative ecological, social and and economical consequences of such intense erosion historically promoted the ecological restoration of these terrains. In a small catchment of 390 ha (Saignon catchment, France), a first wave of restoration was run in 1876-78, mainly through Austrian black pine plantation on eroded gully sides. A second wave occurred in 2002 and focused on gullies partly vegetated on their sides but still showing active gully beds. Bioengineering works, made of barriers of Salix cuttings, were implanted in gully beds to increase sedimentation and in turn to re-initiate soil formation. This strategy proved to be efficient to retain sediment and to favor plant colonization. The aim of this study was to investigate soil fertility of sediment mounds retained in gully beds 9 to 136 years after their rehabilitation. To answer this question, we compared the topsoil (0-10 cm depth) chemical fertility of 6 gully beds restored in 2002 with bioengineering works to the one of 5 gully beds belonging to gullies stabilized by pine plantation 136 years ago. As a control, sediment mounds found in 15 bare gully beds were also studied. In each gully, basic soil characteristics of composite samples were assessed. Vegetative cover, plant richness and litter accumulation were also measured. We found that soil organic carbon and total nitrogen content significantly increased with time since gully bed rehabilitation (4.3±0.4 / 12±1 / 21±2 g.kg-1 and 0.80±0.02 / 1.4±0.02 / 1.7±0.07 g.kg-1) for bare gully beds and gully beds rehabilitated 9 and 140 years ago, respectively. Carbonate content was lower in restored gullies (average value of 242±5 g.kg-1) compared to control ones (547±13 g.kg-1). These results suggest that pedogenesis was engaged in both sets of restored gullies (decarbonatation process). Available phosphorus was lowest in

  2. New and Recent Gully Activity on Mars

    NASA Astrophysics Data System (ADS)

    Dundas, C. M.; McEwen, A. S.; Diniega, S.; Byrne, S.

    2009-12-01

    New bright gully deposits were observed on Mars in 2006 [1], and several similar deposits were reported in 2007 [2]. As gullies may have formed due to the action of liquid water, these new deposits are of considerable interest. Images from HiRISE have shown many more fresh-appearing deposits associated with gullies. In order to better understand recent gully activity, we have searched >1400 HiRISE images for fresh deposits, focusing on the southern mid-latitudes; we exclude dune gullies, which are discussed elsewhere [3]. Very fresh deposits (distinct from other gully deposits in tone and without obvious modification such as development of eolian ripples) have so far been found at almost 50 sites between 29 and 55 S. Those poleward of 40 S latitude show no obvious orientation preference. Equatorward of 40 S, recent deposits show a strong tendency to face the pole, consistent with typical gully orientations at this latitude. Mass wasting should not show orientation preferences unless slopes are systematically steeper in one direction. In fact, steep slopes in the southern mid-latitudes are more likely to face the equator [4], but gullies might locally provide very steep slopes prone to failure. We have noted ten sites where the formation time can be constrained by a preexisting image without the deposit, including the two reported by [1]. Seven of these are on pole-facing slopes. Formation times for eight of these deposits are known to better than one Mars year. These formation intervals tend to exclude late spring and summer; this is consistent with the season reported for dune gully activity [3], but may be affected by non-random image times. Many of the observed new deposits could be consistent with thin coatings, but two deposits in Gasa Crater (35.7 S, 129.4 E) have before-and-after HiRISE coverage showing changes on fans and the distal part of the channels. These include movement of boulders and visible topographic changes, indicating that those deposits are

  3. Seasonal activity and morphological changes in martian gullies

    USGS Publications Warehouse

    Dundas, Colin M.; Diniega, Serina; Hansen, Candice J.; Byrne, Shane; McEwen, Alfred S.

    2012-01-01

    Recent studies of martian dune and non-dune gullies have suggested a seasonal control on present-day gully activity. The timing of current gully activity, especially activity involving the formation or modification of channels (which commonly have been taken as evidence of fluvial processes), has important implications regarding likely gully formation processes and necessary environmental conditions. In this study, we describe the results of frequent meter-scale monitoring of several active gully sites by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). The aim is to better assess the scope and nature of current morphological changes and to provide improved constraints on timing of gully activity on both dune and non-dune slopes. Our observations indicate that (1) gully formation on Mars is ongoing today and (2) the most significant morphological changes are strongly associated with seasonal frost and defrosting activity. Observed changes include formation of all major components of typical gully landforms, although we have not observed alcove formation in coherent bedrock. These results reduce the need to invoke recent climate change or present-day groundwater seepage to explain the many martian gullies with pristine appearance.

  4. Restoration of badlands through applying bio-engineering techniques in active gully systems: Evidence from the Ecuadorian Andes

    NASA Astrophysics Data System (ADS)

    Borja, P.; Vanacker, V.; Alvarado, D.; Govers, G.

    2012-04-01

    A better insight in the processes controlling sediment generation, transport and deposition in badlands is necessary to enhance restoration of degraded soils through eco-engineering techniques. In this study, we evaluate the effect of different bio-engineering measures on soil and slope stability. Five micro-catchments (of 0.2 to 5 ha) were selected within a 3 km2 area in the lower part of the Loreto catchment (Southern Ecuadorian Andes). The micro-catchments differ only by land cover and degree of implementation of soil and water conservation measures. Bio-engineering techniques were used to construct dikes made of fascines of wooden sticks and earth-filled tires in active gully beds, where they are most efficient to reduce water and sediment transport. The experimental design consists of three micro-catchments within highly degraded lands: (DI) micro-catchment with bio-engineering measures concentrated in the active gully beds, (DF) with reforestation of Eucalyptus trees, and (DT) reference situation without any conservation measures. Two micro-catchments were monitored in agricultural lands with (AI) and without (AT) bio-engineering measures in the active gully beds. All catchments were equipped with San Dimas flumes to measure water flow, and sediment traps to monitor sediment export. In the (active) gully beds, various parameters related to gully stability (soil water content, bed elevation, vegetation cover, sedimentation/erosion) were monitored at weekly intervals. First results show that bio-engineering techniques are efficient to stabilize active gully beds through a reduction of the rapid concentration of excess rainfall and the sediment production and transfer. Fascines made of wooden sticks are far more efficient than earth-filled tires. Sediment deposition behind dikes is strongly dependent on precedent rainfall events, and the slope and vegetation cover of the gully floor. The sediment deposited facilitates colonization of the gully floor by native

  5. Multiple Episodes of Recent Gully Activity Indicated by Gully Fan Stratigraphy in Eastern Promethei Terra, Mars.

    NASA Astrophysics Data System (ADS)

    Schon, S.; Head, J.; Fassett, C.

    2008-09-01

    Introduction Gullies are considered among the youngest geomorphic features on Mars based upon their stratigraphic relationships, superposition on steep slopes and distinctive morphology in unconsolidated sediment. Multiple formation hypotheses have been proposed, which can be divided into three broad classes: entirely dry mechanisms (e.g., [1,2]), wet mechanisms invoking groundwater or ground ice (e.g., [3,4]) and wet mechanisms invoking surficial meltwater (e.g., [5,6,7,8]). It has been difficult to differentiate between these hypotheses based upon past observations and it remains possible that gullies are polygenetic landforms. This study presents stratigraphic relationships in the depositional fan of a crater wall gully system that suggest: (1) multiple episodes of alluvial fan-style deposition, (2) very recent depositional activity that is younger than a newly recognized rayed crater, and (3) surficial snowmelt as the most likely source of these multiple episodes of recent gully activity. Gully-Fan Stratigraphy In Eastern Promethei Terra an ~5 km-diameter crater is observed with a well-developed gully system (Fig. 1) and several smaller gullies in its northnortheast wall. The large gully system (composed of a small western gully and larger eastern gully) shows evidence for incision into the crater wall country rock and has multiple contributory sub-alcoves and channels. The depositional fan associated with this gully system is bounded on its western side by a small arcuate ridge swell that is not observed on the eastern side of the fan. This ridge is interpreted as a moraine-like structure that may have bounded a glacially-formed depression into which the fan is deposited [8]. Similar depressions with bounding ridges are commonly observed in this latitude band (~30-50°S) in association with deeply incised gully alcoves [9,10,11]. This gully fan is composed of multiple lobes with distinct lobe contacts, incised channels, and cut-andfill deposits - all features

  6. Comparison of submarine gully morphologies in passive and active margin settings

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Shumaker, L.; Johnstone, S.; Graham, S. A.

    2015-12-01

    Passive and active tectonic margins have inherently different hypsometry, due to local patterns of deformation and subsequent impacts on the style of sedimentation. One way we can analyze and compare the two settings is through observation of submarine gullies, which are small channel features that form along the continental slope as it descends to the ocean floor. By documenting the geometries of gullies that have formed on passive margins and gullies that have formed on active margins, we attempt to distinguish differences in gully morphologies in these two settings. We manually mapped over 600 gullies and interfluves from shaded relief and contour maps generated from bathymetric data across the globe, including the coast of California, the Beaufort Sea, and the Black Sea. We extrapolated and plotted elevation profiles of the gullies along their downslope distance, and compared a range of gully properties, such as length, spacing, and slope, to look at the correlations among those elements of gullies and their tectonic setting. We find that gullies forming on active margins show the greatest variability in their slopes, exhibiting both the steepest and the shallowest slopes of the dataset. The slopes of the passive margin gullies fall within the range of the active margin gully slopes, but interestingly, we note patterns in the ranges of gully steepness at different localities. These results differ from our our anticipation that active margin gullies are steeper than passive margin gullies, but suggest that gullies in all settings display a variety of morphologies. Additional mapping of active margin gullies will better determine if there are morphological differences between the two settings.

  7. Present Day Activity of South Polar Gullies on Mars

    NASA Astrophysics Data System (ADS)

    Raack, J.; Reiss, D.; Ruesch, O.; Hiesinger, H.

    2012-04-01

    Here we report on clearly identified seasonal changes of gullies observed within the last two martian years (MY) on slopes of a south polar pit, which is located in a filled crater (diameter ~54 km) north of Sisyphi Cavi at ~68.5°S and ~1.5°E. Using new high-resolution imaging (High Resolution Imaging Science Experiment, HiRISE), temperature (Thermal Emission Spectrometer, TES) and spectral data (Compact Reconnaissance Imaging Spectrometer for Mars, CRISM; Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité, OMEGA), we analyzed the exact timing of changes of gullies and detect the possible medium (CO2, H2O or dry) and mechanism which initiate present day gully activity. Two locations in the study region with clear modifications of gullies were identified in MY 29 between LS 226° and LS 247° and between LS 209° and LS 247°. In MY 30 changes occur in both locations between LS 218° and LS 249°. Modifications are the formation of a new small apron and new deposits within the channel, both associated with the deposition of dark material. Erosion in gully alcoves or channels was not observed. TES data show temperatures between ~180 and ~240 K within the period of gully modifications. Maximum temperatures in the region rise up to ~285 K between LS ~270° and ~310°. Spectral data show a CO2-cover of the study region until LS 227°. CO2-ice free surface are spectrally observed for the first time at LS 249°. H2O was not spectrally detected in the study region and a mixture of CO2 and H2O as presented in [1] cannot be clearly detected. Unfortunately, there are no spectral data available between LS 227° and 249°. Modifications of gullies imply seasonal volatile activity. The activity can be narrowed down to occur between LS 226° and 247° at mean temperatures between ~180 and ~240 K. This is in the range of temperatures where CO2 sublimates back into the atmosphere. Based on the temperature range, the most likely candidate for the observed new

  8. A summary of present-day gully formation and activity on Mars

    NASA Astrophysics Data System (ADS)

    Diniega, Serina; Hansen, Candice; McEwen, Alfred; Dundas, Colin; Byrne, Shane

    2016-07-01

    Over the past decade, gully activity has been carefully monitored on a range of slopes, including dune slopes [1-3] and crater walls [2-4]. Within the southern mid-latitudes, substantial changes in gully morphology have been observed. On dune slopes, observed activity includes major incision (forming a new channel or expanding an existing channel), changes in channel sinuosity, expansion of alcoves, and deposition of an extensive new apron. On rockier slopes, observed activity has cut new channel segments and small terraces, abandoned other channels, and deposited boulder-rich lobate features. Many of these morphologies have been treated as indicative of fluvial processes. However, long-term monitoring campaigns with High Resolution Imaging Science Experiment (HiRISE) data [2-5] of almost 500 gully locations, have shown that the timing of this current activity is generally correlated with the presence of seasonal frost [1-5]. Moreover, the distribution of seasonal frost on slopes is similar to the orientation distribution of gullies [3,6]. Most seasonal frost is CO2, and this is likely the main cause of current activity. Recent modeling has shown that CO2 sublimation from within the regolith pores would be sufficient to create the types of geomorphology seen within martian gullies [7]. Water frost may be involved in some small-scale activity [5]. Liquid water is unlikely to be relevant, because the abundance of water frost is generally low [8] and melting is difficult. An additional current focus is on the north polar sand sea, where "gullies" (generally lacking a channel) have been observed to form on dune slopes over seasonal and annual timescales. There, we aim to differentiate between either a general aeolian [8] or seasonal frost driver [9,10] for the formation process. For these features, formation timing estimates are often less constrained because HiRISE images are not acquired during fall and winter, due to the polar hood and darkness. Thus, analysis of

  9. Active polar gullies on Mars and the role of carbon dioxide.

    PubMed

    Hoffman, Nick

    2002-01-01

    The detection of geologically recent channels and gullies on Mars has been interpreted as evidence for recent water activity on this arid and cold planet. The presence of active water would have considerable implications for the history of Mars and for the potential for an active near-surface biota; however, water is not the only substance that can flow and may actually be one of the least likely candidates when the modern permafrost environment is considered. Here, a key site of recent gully and channel development on Mars is reported at 71 degrees S in Sisyphi Cavi, within the annual zone of polar CO2 ice and snow accumulation. Superposition of channel features over and/or through the defrosting CO2 snowpack shows that the channels are active at the present day and probably have fluid flows every spring during the annual defrosting. In itself, this is a significant observation as active fluid flows of any nature have not yet been proven on Mars. However, the ambient temperature at the time of gully activity appears to require a role for CO2 in the formation of the channels, rather than water. A model is proposed for gas-lubricated flow in the channels based on avalanching of CO2 snowpack and clastic debris. If similar mechanisms are responsible for all the recent gullies on Mars, then perhaps no near-surface astrobiological targets are available.

  10. Present-Day Seasonal Gully Activity in a South Polar Pit (Sisyphi Cavi) on Mars

    NASA Astrophysics Data System (ADS)

    Raack, Jan; Reiss, Dennis; Appéré, Thomas; Vincendon, Mathieu; Ruesch, Ottaviano; Hiesinger, Harald

    2014-05-01

    Seasonal activity of gullies under current climatic conditions on Mars was observed by [1-7]. Dundas et al. [2] reviewed the present-day activity of classical gullies (including the gully presented in this work), dune gullies, and other mass wasting processes in the southern hemisphere on Mars. Recent polar gullies in Sisyphi Cavi were also analyzed by [8], who estimated ages of about 20 ka to 20 Ma for the gullies. In this study we focus on a single gully in Sisyphi Cavi, located in the south polar region at 1.44° E and 68.54° S. The gully occurs on the gullied equator-facing slope of an isolated polar pit within an infilled impact crater. Multi-temporal high-resolution image data analyses show new deposits at the terminus of the gully channel and on the gully apron within spring (after solar longitudes of 236°) of martian years (MY) 29 and 31. In MY 29 deposition of material shortens the channel by about 40 m; in MY 31 a new deposit at the western flank of the gully apron with approximately 300-600 m3 of material is visible [3]. Our morphological investigations show that the identified new deposits were formed by dark flows through the entire gully deposited on top of the apron between LS ~218° and ~226°. Thermal data show a temperature increase between solar longitudes (LS) ~218° and ~226°. Near-infrared spectral data show relatively constant band strengths of CO2 ice and H2O ice in this time range. After the formation of the dark flows (after LS ~226°), temperatures increase rapidly from ~180 K to >~270 K at LS ~250°. At this time, spectral data indicate that all volatiles on the surface sublimated. However, an earlier beginning of sublimation when the dark flows were observed (between LS ~218° and ~226°) is likely, due to the fact that the instruments can only show the last phase of sublimation (decrease of volatile band strengths) [3]. Spectral modeling shows that from winter to mid-spring, the surface of the studied area is covered by CO2 slab

  11. Restoration of active gully systems following the implementation of bioengineering techniques.

    NASA Astrophysics Data System (ADS)

    Borja, Pablo; Vanacker, Veerle; Govers, Gerard

    2015-04-01

    Intensive land use in the central parts of the Andean basin has led to widespread land degradation. The formation of badlands dates back from the 1950s and 1960s. Several studies indicate that human activities have accelerated mountain erosion rates by up to 100 times. In this study, we have evaluated the effects of bio-engineering works aiming to stabilize degraded catchments. Five micro-catchments (0.2 up to 5 ha) have been selected within a 3 km2 area in the lower part of the Loreto catchment (Southern Ecuadorian Andes). The five micro-catchments differ in vegetation cover and implementation of bio-engineering works. The experimental design consisted of three micro-catchments: (1) DI with conservation works, (2) DF with reforestation by Eucalyptus sp and (3) DT with no conservation works. Two micro-catchments have been monitored in an agricultural area: with (AI) and without (AT) bio-engineering works in the active gullies. Small checkdams were constructed in the gully floors of two of the micro-catchments in the badland area (DI) and the agricultural area (AI). The checkdams are made of wood and tires. Water flow has been measured in every micro-catchment, while sediment traps were constructed to monitor sediment transport. Results show that bio-engineering techniques are effective to stabilize active gullies. Deposition of sediments in manmade dams is strongly dependent on previous rainfall events, as well as gully channel slope, and its vegetation cover. From the experimental data, an I30 max threshold value was determined. Above this threshold value, all micro-catchments are actively contributing sediment to the main river system. The checkdams built with wood and tires have an efficiency of 70%, and were shown to be very effective to stabilize active gullies in bad lands through significant reduction (about 62%) of the amount of sediment exported from the micro-catchments. Key words: degraded soils, erosion, sediment, restoration, reforestation

  12. Possible seasonal activity of gullies on an sand dune (Russell crater, Mars)

    NASA Astrophysics Data System (ADS)

    Jouannic, Gwénaël.; Gargani, Julien; Costard, François

    2010-05-01

    Recent work has shown that gullies are among the most youthful features on Mars (Malin and Edgett, 2000; Costard et al., 2002; Reiss and Jaumann, 2003, Malin et al., 2006). Here we show that the gullies located on the Russell Crater dune are not only extremely youthful but also seem to be still actives. Various geomorphological features consistent with a seasonal activity suggest reactivated flows over the last three terrestrial years. Moreover, using an assemblage of 26 HiRISE images over a 31 month period (November 2006-May 2009) and superposed with MOLA tracks, we performed a quantitative analysis of the sinuosity and branching of the gullies on the shallow slope of the Russell crater. These geomorphologicals features suggest that debris flow have been formed by a fluid flow. As pure water generally is not thought to be stable on the surface of Mars under current conditions, these gullies could be indicative of a highly localized zone of meta-stability heretofore unidentified in the literature or by a highly mineralized water. Equally, the occurrence of the gullies on a dune may point to a near-surface source, i.e. near surface permafrost (Vedie et al. 2008), that could have been emplaced under conditions associated with late Amazonian obliquity excursions (Costard et al., 2002). Nevertheless, the precise composition of the fluid (CO2, mineralized water,…) is still unknown. Costard, F., Forget, F., Mangold, N., Peulvast, J.P., 2002. Formation of recent martian debris flow by melting of near-surface ground ice at high obliquity. Science, 295, 110-113. Malin, M.C., Edgett, K.E., 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science, 288, 2330-2335. Malin, M.C., Edgett, K.E., Posiolova, L.V., McColley, S.M., Dobrea, E.Z., 2006. Present day impact crater rate and contemporary gully activity on Mars. Science, 314, 1573-1577. Reiss, D., Jaumann, R., 2003. Recent debris flows on Mars : Seasonal observations of the Russell Crater dune field

  13. Martian Gullies

    NASA Technical Reports Server (NTRS)

    2004-01-01

    8 May 2004 This March 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a gullied crater wall at southern mid-latitude near 35.5oS, 223.0oW. Formation of such gullies might have involved flowing liquid water. The Mars science community has been debating, since they were first reported in June 2000, whether such gullies were carved by water, carbon dioxide, or perhaps formed in completely dry, granular material without the influence of a fluid. The scientists have also debated whether the water--if it was water--started out in the form of ground ice, a snow pack, or liquid groundwater. Since June 2000, many hundreds of new gully locations--and tens of thousands of individual gullies--have been identified. Their relative youth suggests to some the possibility that Mars today has water or ice within less than 1 kilometer of the surface--a depth that may be readily accessible to future explorers. This picture is illuminated by sunlight from the upper left and covers an area about 3 km (1.9 mi) across.

  14. Role of native and exotic woody vegetation in soil restoration in active gully systems (southern Ecuador)

    NASA Astrophysics Data System (ADS)

    Borja Ramon, Pablo; Alvarado Moncayo, Dario; Vanacker, Veerle; Cisneros, Pedro; Molina, Armando; Govers, Gerard

    2015-04-01

    Revegetation projects in degraded lands have the potential to recover essential soil functions. If vegetation restoration is combined with bioengineering techniques, such as the construction of retention dams in active gully systems, soil restoration could be enhanced. One important aspect of this process is the role of vegetation on restoration of soil chemical and physical properties. There is currently a lack of knowledge on the potential of soil restoration in active badland systems, as most studies have concentrated on the direct and visible effect of revegetation on erosion control. The aim of this study is to evaluate the role of revegetation and bioengineering works on the restoration of soil physical and chemical properties. The analyses are realized in a highly degraded area of 3 km2, located in the lower part of the Loreto catchment (Southern Ecuadorian Andes). First, the soil physical and/or chemical parameters that are most sensitive to track environmental change were evaluated. Second, the role of vegetation on soil restoration was quantified. . Soil samples were taken in sites with different vegetation cover, land use and physiographic position. The following physical and chemical parameters were measured: volumetric water content (θsat, θact), bulk density, pH, texture, organic matter, C and N content. Our first results do not show a clear relationship between volumetric water content at saturation (θsat), bulk density, or C content. The saturation water content does not vary significantly between different sites, or land use types. However, significant differences are found between sites at different stages of restoration; and this for most chemical and physical soil properties. Vegetation cover (%) appears to exert a strong control on the C content in the mineral soils. The highest C values are found in soils of forest plantations with Eucalyptus and Pinus species. These plantations are located in areas that were previously affected by active

  15. Gullied Slope

    NASA Technical Reports Server (NTRS)

    2005-01-01

    20 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies formed on an equator-facing slope among mounds in Acidalia Planitia. Similar gullies occur in a variety of settings at middle and polar latitudes in both martian hemispheres.

    Location near: 49.8oN, 22.7oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  16. Gullied Depression

    NASA Technical Reports Server (NTRS)

    2006-01-01

    26 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies formed in the wall of a depression located on the floor of Rabe Crater west of the giant impact basin, Hellas Planitia. Gullies such as these are common features on Mars, but the process by which they are formed is not fully understood. The debate centers on the role and source of fluids in the genesis of these features.

    Location near: 44.1oS, 325.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  17. Gully geometry: what are we measuring?

    NASA Astrophysics Data System (ADS)

    Casalí, Javier; Giménez, Rafael; Ángel Campo, Miguel

    2014-05-01

    representation of the same soil surface previous to gully development (DEM2). The intersection -in a certain point along the gully longitudinal axis (X)- of the resulting DEM with a plane perpendicular to the X-axis results in the cross section area of the gully in this point. The cross section width (Wi) is defined as the length of the horizontal projection of the straight line linking the upper ends of both sides in the cross section (A1-A2 line). This exercise could be repeated in as many points as we want along X-axis, and the corresponding width defined as just stated. On the other hand, the maximum cross section depth can now be directly defined as the distance from the deepest point in the gully bed to the A1-A2 line. But, as quoted before: is this maximum depth meaningful? Is it representative? This is subject to discussion. In addition, it is necessary to define the concepts of effective width (We), effective depth (De), and effective width/ depth ratio of a gully. Effective width will be defined as the average of the individual widths, Wi. At that point, the definition of gully volume (V) is required, being V the subtraction of DEM2 from DEM1. Then, effective depth is De= V / We. De, We and gully length L can be used to represent a gully as a prism with rectangular base. Although this simplification is to some extent an obvious source of experimental error, it allows as to easily define comparable magnitudes. In this work, several examples of the application of this approach are shown. Although most of these reflections and considerations are thought to ephemeral gullies, they may be also applied to other larger eroded channels.

  18. Lyell Gullies

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03190 Lyell Gullies

    These gullies are located on a cliff-face within Lyell Crater.

    Image information: VIS instrument. Latitude 69.6S, Longitude 346.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Present-day impact cratering rate and contemporary gully activity on Mars.

    PubMed

    Malin, Michael C; Edgett, Kenneth S; Posiolova, Liliya V; McColley, Shawn M; Dobrea, Eldar Z Noe

    2006-12-01

    The Mars Global Surveyor Mars Orbiter Camera has acquired data that establish the present-day impact cratering rate and document new deposits formed by downslope movement of material in mid-latitude gullies on Mars. Twenty impacts created craters 2 to 150 meters in diameter within an area of 21.5 x 10(6) square kilometers between May 1999 and March 2006. The values predicted by models that scale the lunar cratering rate to Mars are close to the observed rate, implying that surfaces devoid of craters are truly young and that as yet unrecognized processes of denudation must be operating. The new gully deposits, formed since August 1999, are light toned and exhibit attributes expected from emplacement aided by a fluid with the properties of liquid water: relatively long, extended, digitate distal and marginal branches, diversion around obstacles, and low relief. The observations suggest that liquid water flowed on the surface of Mars during the past decade.

  20. Present-day impact cratering rate and contemporary gully activity on Mars.

    PubMed

    Malin, Michael C; Edgett, Kenneth S; Posiolova, Liliya V; McColley, Shawn M; Dobrea, Eldar Z Noe

    2006-12-01

    The Mars Global Surveyor Mars Orbiter Camera has acquired data that establish the present-day impact cratering rate and document new deposits formed by downslope movement of material in mid-latitude gullies on Mars. Twenty impacts created craters 2 to 150 meters in diameter within an area of 21.5 x 10(6) square kilometers between May 1999 and March 2006. The values predicted by models that scale the lunar cratering rate to Mars are close to the observed rate, implying that surfaces devoid of craters are truly young and that as yet unrecognized processes of denudation must be operating. The new gully deposits, formed since August 1999, are light toned and exhibit attributes expected from emplacement aided by a fluid with the properties of liquid water: relatively long, extended, digitate distal and marginal branches, diversion around obstacles, and low relief. The observations suggest that liquid water flowed on the surface of Mars during the past decade. PMID:17158321

  1. Monitoring and statistical modelling of sedimentation in gully pots.

    PubMed

    Post, J A B; Pothof, I W M; Dirksen, J; Baars, E J; Langeveld, J G; Clemens, F H L R

    2016-01-01

    Gully pots are essential assets designed to relief the downstream system by trapping solids and attached pollutants suspended in runoff. This study applied a methodology to develop a quantitative gully pot sedimentation and blockage model. To this end, sediment bed level time series from 300 gully pots, spanning 15 months, were collected. A generalised linear mixed modelling (GLMM) approach was applied to model and quantify the accumulation of solids in gully pots and to identify relevant physical and catchment properties that influence the complex trapping processes. Results show that the retaining efficiency decreases as sediment bed levels increase. Two typical silting evolutions were identified. Approximately 5% of all gully pots experienced progressive silting, eventually resulting in a blockage. The other gully pots show stabilising sediment bed levels. The depth of the sand trap, elapsed time since cleaning and the road type were identified to be the main properties discriminating progressive accumulation from stabilising sediment bed levels. Furthermore, sediment bed levels exhibit no residual spatial correlation, indicating that the vulnerability to a blockage is reduced as adjacent gully pots provide a form of redundancy. The findings may aid to improve maintenance strategies in order to safeguard the performance of gully pots. PMID:26512802

  2. Knickpoint series of gullies along the Luoyunshan Piedmont and its relation with fault activity since late Pleistocene

    NASA Astrophysics Data System (ADS)

    Sun, Changbin; Wan, Tianfeng; Xie, Xinsheng; Shen, Xiaoming; Liang, Kuan

    2016-09-01

    The authors surveyed the longitudinal profiles of 28 gullies across the Luoyunshan Piedmont fault (LPF) by differential GPS and dating of sediments well preserved in the typical terraces and obtained 6-level knickpoint series of the gullies along the Luoyunshan Piedmont. The authors compared it with previous studies on the paleo-earthquakes of the LPF revealed by trenches and found that the paleo-earthquake events from knickpoint and trench studies are in good agreement in terms of the time of occurrence and vertical displacement of the fault. It shows studying the paleo-earthquake events of the fault by knickpoint series is feasible. At last, the authors established a more complete paleo-earthquake sequence of the LPF supported by geomorphologic and sedimentary evidence, i.e., six paleo-earthquake events happened on the LPF from about 28,000 years ago; the LPF has the characteristic of quasi-periodic recurrence and the average recurrence interval is 4585 years. The vertical displacement of the paleo-earthquake events is 2.4-3.0 m; according to the empirical equations between co-seismic displacement and earthquake magnitude the magnitude of these events is Ms 7.0-7.5. This study aims to complement and improve the traditional trenching method, provide theoretical and methodological support for the research of active tectonics, and contribute important information for the seismic hazard assessment of the densely populated Linfen area.

  3. An empirical investigation of gully widening rates in upland concentrated flows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion, in its myriad forms, devastates arable land and infrastructure. As an integral landscape erosion feature, gully erosion is a complicated system as its evolution is controlled by upward migration of a gully head (headcut face), incision of the gully bed (plunge pool) and gravitational m...

  4. Martian hillside gullies and icelandic analogs

    NASA Astrophysics Data System (ADS)

    Hartmann, William K.; Thorsteinsson, Thorsteinn; Sigurdsson, Freysteinn

    2003-04-01

    We report observations of Icelandic hillside gully systems that are near duplicates of gullies observed on high-latitude martian hillsides. The best Icelandic analogs involve basaltic talus slopes at the angle of repose, with gully formation by debris flows initiated by ground water saturation, and/or by drainage of water from upslope cliffs. We report not only the existence of Mars analog gullies, but also an erosional sequence of morphologic forms, found both on Mars and in Iceland. The observations support hypotheses calling for creation of martian gullies by aqueous processes. Issues remain whether the water in each case comes only from surficial sources, such as melting of ground ice or snow, or from underground sources such as aquifers that gain surface access in hillsides. Iceland has many examples of the former, but the latter mechanism is not ruled out. Our observations are consistent with the martian debris flow mechanism of F. Costard et al. (2001c, Science295, 110-113), except that classic debris flows begin at midslope more frequently than on Mars. From morphologic observations, we suggest that some martian hillside gully systems not only involve significant evolution by extended erosive activity, but gully formation may occur in episodes, and the time interval since the last episode is considerably less than the time interval needed to erase the gully through normal martian obliteration processes.

  5. Laboratory simulation of debris flows over sand dunes: Insights into gully-formation (Mars)

    NASA Astrophysics Data System (ADS)

    Jouannic, Gwenaël; Gargani, Julien; Conway, Susan J.; Costard, François; Balme, Matthew R.; Patel, Manish R.; Massé, Marion; Marmo, Chiara; Jomelli, Vincent; Ori, Gian G.

    2015-02-01

    Gully morphology (often summarized as comprising an alcove, channel and debris apron) is one of the key elements used to support the argument for liquid water in the recent past on Mars. Nevertheless, the processes that create different gully morphologies, on both Mars and Earth, are not fully understood. One of the puzzling morphologic attributes of Martian dune gullies is their apparent lack of an apron, or terminal deposit, which has caused debate about their formation process. Several physical processes such as runoff, debris flows, granular flows, and sliding blocks falling downslope could explain the formation of these gullies. In this work, we focus on the role of liquid in the substrate as well as in the flow and choose to experimentally test the plausibility of this hypothesis. We performed a series of analogue experiments to investigate the formation of gullies on sand dune-like substrates. We used controlled flows of water over an inclined sand-box to produce gully-like forms. Ice-rich sedimentary substrates were used, including substrates that included a thin liquid water-saturated thawed layer (an 'active layer') above the ice-saturated zone to give an analogue for a 'periglacial' environment. We quantitatively demonstrate that debris flow processes in 'periglacial' experiments are conducive to the formation of narrow and long channels with small terminal deposits with perched channels. By re-analysis of Martian elevation data for dune-gullies on Mars, we have found good evidence that such terminal deposits could exist. Our experiments revealed that increased water content in the thawed layer above the frozen bed increases flow-length due to the subsequent reduction in infiltration capacity. Water is incorporated into the flow by erosion of the wet thawed layer (sand plus water) and by drainage of the thawed layer. Using a Mars environment simulation chamber, we found that atmospheric pressure conditions seem to have a limited influence on the

  6. Responses of streamflow and sediment load to climate change and human activity in the Upper Yellow River, China: a case of the Ten Great Gullies Basin.

    PubMed

    Liu, Tong; Huang, He Qing; Shao, Mingan; Yao, Wenyi; Gu, Jing; Yu, Guoan

    2015-01-01

    Soil erosion and land desertification are the most serious environmental problems globally. This study investigated the changes in streamflow and sediment load from 1964 to 2012 in the Ten Great Gullies area of the Upper Yellow River. Tests for gradual trends (Mann-Kendall test) and abrupt changes (Pettitt test) identify that significant declines in streamflow and sediment load occurred in 1997-1998 in two typical gullies. A comparison of climatic variability before and after the change points shows no statistically significant trends in annual precipitation and potential evapotranspiration. Human activities have been very active in the region and during 1990-2010, 146.01 and 197.62 km2 of land were converted, respectively, to forests and grassland, with corresponding increases of 87.56 and 77.05%. In addition, a large number of check dams have been built up in the upper reaches of the ten gullies. These measures were likely responsible for the significant decline in the annual streamflow and sediment load over the last 49 years.

  7. Gullies in Noachis

    NASA Technical Reports Server (NTRS)

    2004-01-01

    16 May 2004 This full-resolution (1.5 m/pixel; 5 ft/pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies on a crater wall in northern Noachis Terra. The gullies might have formed by the seepage of martian groundwater or melting of ice. However, the Mars science community is still studying this topic and no consensus has yet emerged as to whether such gullies could have formed without water. These gullies are located near 32.1oS, 12.9oW. The 300 meter scale bar also equals 328 yards (984 feet). The picture is illuminated by sunlight from the left/upper left.

  8. Liquid Water on the Surface of Mars Today: Present Gully Activity Observed by the Mars Reconnaissance Orbiter (MRO) and Mars Global Surveyor (MGS) and Direction for Future Missions

    NASA Astrophysics Data System (ADS)

    Harrison, T. N.; Malin, M. C.; Edgett, K. S.

    2009-12-01

    Eight new flows in martian mid-latitude gullies have been found using the MRO Context Camera and MGS Mars Orbiter Camera. Each formed during 1999-2009. Using MRO HiRISE images, we find that the morphology and inferred emplacement behavior of these features is consistent with those of debris flows fluidized by a liquid medium and not by dry, granular flows. Evidence comes from the patterns of flow around obstacles, ponding in and subsequent overtopping of topographic depressions, and super-elevation of deposits on channel banks where the channels change direction, attributes consistent with a liquid but not with fluid-like granular flow. Additional evidence includes anastomoses in distal reaches and lobate terminations. Of the 8 flows, 3 have formation dates constrained to within a single Mars year (although not the same year); these 3 formed during autumn to early spring, demonstrating that summer warming is not participating in creating the liquid (i.e., that would melt snow or ice). The new gully deposits indicate that some gullies are currently active, suggesting that Mars has liquid water today and it occasionally appears on the planet’s surface. NASA’s Mars Exploration Program has focused on the “follow the water” theme and is now shifting toward “habitability” and life detection. Places where liquid water comes to the Martian surface today warrant detailed investigation. Martian astrobiology involves the search for evidence of extinct and extant life. Discovery of ancient sedimentary rocks shifted emphasis from the Viking-era pursuit of present-day microbial life to MSL’s focus on habitable environments. Recent descriptions of contemporary methane production have renewed interest in searching for extant life. Missions to locations of potential present day life, whether indicated by methane or liquid water, must deal with the associated planetary protection issues (they are “special regions”). More information about such locations is critical

  9. Gullies of Gorgonus Chaos

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 11 June 2002) The Science This fractured surface belongs to a portion of a region called Gorgonum Chaos located in the southern hemisphere of Mars. Gorgonum Chaos is named after the Gorgons in ancient Greek mythology. The Gorgons were monstrous sisters with snakes for hair, tusks like boars and lolling tongues who lived in caves. As it turns out this is indeed a fitting name for this region of Mars because it contains a high density of gullies that 'snake' their way down the walls of the troughs located in this region of chaos. Upon closer examination one finds that these gullies and alluvial deposits, initially discovered by Mars Global Surveyor, are visible on the trough walls (best seen near the bottom of the image). These gullies appear to emanate from a specific layer in the walls. The gullies have been proposed to have formed by the subsurface release of water. The Story This fractured, almost spooky-looking surface belongs to a region called Gorgonum Chaos in the southern hemisphere of Mars. Chaos is a term used for regions of Mars with distinctive areas of broken terrain like the one seen above. This area of Martian chaos is named after the Gorgons in ancient Greek mythology. The Gorgons were monstrous sisters with snakes for hair, tusks like boars, and lolling tongues, who lived in caves. The Gorgons, including famous sister Medusa, could turn a person to stone, and their writhing, snakelike locks cause revulsion to this day. Given the afflicted nature of this contorted terrain, with all of its twisted, branching channels and hard, stony-looking hills in the top half of the image, this is indeed a fitting name for this region of Mars. The name also has great appeal, because the area contains a high density of gullies that 'snake' their way down the walls of the troughs located in this region of Martian chaos. Gullies are trenches cut into the land as accelerated streams of water (or another liquid) erode the surface. To see these, click on the

  10. GIS technology for spatiotemporal measurements of gully channel width evolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field observations of gully evolution in active croplands have often revealed the presence of a less erodible soil layer that is typically associated with tillage practices (i.e. plowpan). This more erosion-resistant layer limits channel incision forcing the gully channel to expand laterally through...

  11. New insights into gully formation on Mars: Constraints from composition as seen by MRO/CRISM

    NASA Astrophysics Data System (ADS)

    Núñez, J. I.; Barnouin, O. S.; Murchie, S. L.; Seelos, F. P.; McGovern, J. A.; Seelos, K. D.; Buczkowski, D. L.

    2016-09-01

    Over 100 Martian gully sites were analyzed using orbital data collected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and High Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter (MRO). Most gullies are spectrally indistinct from their surroundings, due to mantling by dust. Where spectral information on gully sediments was obtained, a variety of mineralogies were identified. Their relationship to the source rock suggests that gully-forming processes transported underlying material downslope. There is no evidence for specific compositions being more likely to be associated with gullies or with the formation of hydrated minerals in situ as a result of recent liquid water activity. Seasonal CO2 and H2O frosts were observed in gullies at middle to high latitudes, consistent with seasonal frost-driven processes playing important roles in the evolution of gullies. Our results do not clearly indicate a role for long-lived liquid water in gully formation and evolution.

  12. Gullied Trough Wall

    NASA Technical Reports Server (NTRS)

    2004-01-01

    13 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies emergent from beneath erosion-resistant rock layers in a trough south of Atlantis Chaos near 38.9oS, 176.3oW. Gullies such as these are fairly common in depressions at south middle latitudes. Tens of thousands of gullies have been identified in MGS MOC and Mars Odyssey Thermal Emission Imaging System (THEMIS) images. Whether they formed by running liquid water remains a controversial issue. Banked channels, like some shown here, are one form of evidence cited to indicate that a fluid with the properties of liquid water may have been involved. This image covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.

  13. Resprout and Survival of Willow ( Salix) Cuttings on Bioengineering Structures in Actively Eroding Gullies in Marls in a Mountainous Mediterranean Climate: A Large-Scale Experiment in the Francon Catchment (Southern Alps, France)

    NASA Astrophysics Data System (ADS)

    Rey, F.; Labonne, S.

    2015-10-01

    Improving the understanding of the role of vegetation and bioengineering structures on erosion and sedimentation control, especially in torrent-prone catchments in a mountainous Mediterranean climate, has become a key issue today for the scientific community working in ecological engineering and restoration ecology. The objective of this study was to evaluate the performance of willow ( Salix) cuttings in resprouting and survival on bioengineering structures in actively eroding gullies in marls and to identify the factors influencing this performance. Measurements were taken from 2008 to 2011 on 336 bioengineering structures, namely brush layers on wooden sills (BL) and brush layers with brush mats on wooden sills (BLM), using 8890 cuttings of Salix purpurea and Salix incana. These structures were built in 18 gullies of the Francon Catchment in marls (73 ha) in the Southern French Alps. After four growing seasons, the results revealed a total cutting survival rate of 45 %. They also demonstrated that in BLM, brush mats provided better survival (56 %) than brush layers (37 %). In BL, brush layers alone showed 51 % cutting survival. Cutting resprout and survival were observed for all structure aspects. They were positively related to increasing gully size and vegetation cover on gully sides. The results of this large-scale experiment clarified previous data obtained on a limited sample of bioengineering structures, providing further detail and showing that it is possible to use such structures made of willow cuttings to revegetate actively eroding gullies in marls within a mountainous Mediterranean climate.

  14. Resprout and Survival of Willow (Salix) Cuttings on Bioengineering Structures in Actively Eroding Gullies in Marls in a Mountainous Mediterranean Climate: A Large-Scale Experiment in the Francon Catchment (Southern Alps, France).

    PubMed

    Rey, F; Labonne, S

    2015-10-01

    Improving the understanding of the role of vegetation and bioengineering structures on erosion and sedimentation control, especially in torrent-prone catchments in a mountainous Mediterranean climate, has become a key issue today for the scientific community working in ecological engineering and restoration ecology. The objective of this study was to evaluate the performance of willow (Salix) cuttings in resprouting and survival on bioengineering structures in actively eroding gullies in marls and to identify the factors influencing this performance. Measurements were taken from 2008 to 2011 on 336 bioengineering structures, namely brush layers on wooden sills (BL) and brush layers with brush mats on wooden sills (BLM), using 8890 cuttings of Salix purpurea and Salix incana. These structures were built in 18 gullies of the Francon Catchment in marls (73 ha) in the Southern French Alps. After four growing seasons, the results revealed a total cutting survival rate of 45%. They also demonstrated that in BLM, brush mats provided better survival (56%) than brush layers (37%). In BL, brush layers alone showed 51% cutting survival. Cutting resprout and survival were observed for all structure aspects. They were positively related to increasing gully size and vegetation cover on gully sides. The results of this large-scale experiment clarified previous data obtained on a limited sample of bioengineering structures, providing further detail and showing that it is possible to use such structures made of willow cuttings to revegetate actively eroding gullies in marls within a mountainous Mediterranean climate.

  15. Mid-latitude Gullies

    NASA Technical Reports Server (NTRS)

    2005-01-01

    25 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of south mid-latitude gullies on a crater wall. Gullies such as these may have formed by runoff of liquid water.

    Location near: 38.0oS, 167.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  16. Gullies in Crater Wall

    NASA Technical Reports Server (NTRS)

    2004-01-01

    6 April 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies in the wall of a large impact crater in Newton Basin near 41.9oS, 158.1oW. Such gullies may have formed by downslope movement of wet debris--i.e., water. Unfortunately, because the responsible fluid (if there was one) is no longer present today, only the geomorphology of the channels and debris aprons can be used to deduce that water might have been involved. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.

  17. Legacies in Urban Stormwater Management: A Case Study of a Gully Network in Northern Delaware

    NASA Astrophysics Data System (ADS)

    Wehner, C. E.; Claessens, L.; Santangelo, T.; Soroka, A.

    2013-12-01

    Increased stormwater runoff from urban surfaces could lead to erosion and gully formation in areas of steep topographic relief. To reduce these impacts, stormwater management practices are currently required through federal and state stormwater regulations. Before 1990, stormwater was not regulated and would often be directly routed into adjacent lands. Particularly in areas of steep terrain, this would potentially induce erosion and gully formation. This study reports on a wide-scale examination of gully formation from urban stormwater, using a model that examines the increase of runoff from impervious cover and the potential for gully formation. Here we report on a case study for an area on the University of Delaware campus. The area is located in the Piedmont region and drains into the White Clay Creek, a National Wild and Scenic River. Pre-regulation development in this area has led to the formation of a series of gullies with distinct morphological characteristics. This study examines in detail the reach-scale and contributing area controls on gully formation. We conducted a GIS analysis of the local hydrologic network, determined peak flow of each gully, developed a gully susceptibility model that we compared with the site characteristics, and sampled the sediment concentrations of the gully flow during storm events. We also characterized historical land use data and performed field observations for our analysis. We found that the development changed the hydrology of the site, altering the contributing areas of each gully. In addition, field observations revealed distinct rates of incision across gullies as well as along different sections of each gully. We also found that the gullies are still actively eroding, contributing large sediment loads to the downstream White Clay Creek. Our research provides a better understanding of the local and regional factors governing erosion and gully formation. The model that we created will help to identify sites that

  18. Potential of weight of evidence modelling for gully erosion hazard assessment in Mbire District - Zimbabwe

    NASA Astrophysics Data System (ADS)

    Dube, F.; Nhapi, I.; Murwira, A.; Gumindoga, W.; Goldin, J.; Mashauri, D. A.

    Gully erosion is an environmental concern particularly in areas where landcover has been modified by human activities. This study assessed the extent to which the potential of gully erosion could be successfully modelled as a function of seven environmental factors (landcover, soil type, distance from river, distance from road, Sediment Transport Index (STI), Stream Power Index (SPI) and Wetness Index (WI) using a GIS-based Weight of Evidence Modelling (WEM) in the Mbire District of Zimbabwe. Results show that out of the studied seven factors affecting gully erosion, five were significantly correlated (p < 0.05) to gully occurrence, namely; landcover, soil type, distance from river, STI and SPI. Two factors; WI and distance from road were not significantly correlated to gully occurrence (p > 0.05). A gully erosion hazard map showed that 78% of the very high hazard class area is within a distance of 250 m from rivers. Model validation indicated that 70% of the validation set of gullies were in the high hazard and very high hazard class. The resulting map of areas susceptible to gully erosion has a prediction accuracy of 67.8%. The predictive capability of the weight of evidence model in this study suggests that landcover, soil type, distance from river, STI and SPI are useful in creating a gully erosion hazard map but may not be sufficient to produce a valid map of gully erosion hazard.

  19. Evolution of Submarine Gullies on a Prograding Slope: Insights from 3D Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Shumaker, L.; Jobe, Z. R.

    2014-12-01

    Submarine gullies are common features on continental slopes on both passive and active margins, but the processes dictating gully formation and the role of gullies in deep-water sediment transport are topics of debate. The geometries of gullies can provide clues to understanding the processes by which they initiate and grow, particularly when considered in the context of surrounding submarine geomorphology. Further confidence in these interpretations can be gained by tracking the temporal history of gullies with evolution of the continental margin. The 500 km2 Tui 3D seismic survey from the Taranaki Basin, New Zealand, shows continental slope gullies and other channel features in a ~1 km-thick package of prograding shelf-slope clinoforms that developed over Pliocene-Pleistocene time. This dataset allows for documentation of gullies over ~3 Ma, through numerous cycles of initiation and burial. For this study, we manually interpreted clinoform packages to generate 'paleo-seafloor' surfaces that provide context such as position of the shelf edge, slope gradient and azimuth, and relative progradation and aggradation magnitudes. Gully geometries were obtained from detailed seismic interpretation guided by semblance and RMS amplitude imaging on these surfaces. Gullies are low sinuosity, with widths ranging from ~50-150 m and depths from a few tens to <100 m. Gullies are observed to grow in width and relief downslope without evidence for aggradational confinement (levees), and in some cases form gully 'complexes' hundreds of m wide in the lower slope region. These complexes are present through >150 m of stratigraphy, indicating that they are long-lived features on the slope. This further indicates that the frequency of flows along the gullies was enough to maintain their topographic expression during slope progradation and aggradation, and suggests that gullies play an integral role in transport processes on the slope.

  20. How fast do gully headcuts retreat?

    NASA Astrophysics Data System (ADS)

    Vanmaercke, Matthias; Poesen, Jean

    2015-04-01

    Gullies can be a dominant sediment source at field and catchment scales. Over the past decades, several studies have been conducted that quantify gully headcut retreat (GHR) in different environments. Although this led to important site-specific and regional insights, the overall importance of this erosion process or the factors that control it at a global scale remain poorly understood. This study aims to bridge this gap by conducting a meta-analysis of measured GHR rates worldwide. Through an extensive literature review, GHR rates for ca. 900 individual actively retreating gullies (comprising a total measuring period of > 19 000 years) from more than 50 study areas worldwide have been compiled. Each GHR rate was measured by means of repeated field surveys and/or analyses of aerial photographs over a period of at least one year. The collected data shows a very large variability, both in terms of gully dimensions (cross-sectional areas ranging between 0.11 and 816 m² with a median of 4 m²) and GHR rates (ranging between 0.003 and 47 000 m³/y with a median of 2.2 m³/y). Linear GHR rates vary between 0.01 and 70 m/y (median: 0.82 m/y). By means of statistical analyses for a subset of 689 gullies with a known contributing area, we explored which factors are most relevant in explaining the observed 6 orders of magnitudes of variation in volumetric GHR rates. Results show that measured GHR rates are significantly correlated to the runoff contributing area of the gully (r² = 0.13) and the average rainfall depth on a rainy day (i.e. the long-term average annual rainfall depth divided by the average number of rainy days; r² = 0.39). Combined, these two factors explained 57% of the observed variability in average GHR rates. Other factors (e.g. land use or soil type) showed no significant correlation with the observed GHR rates. This may be attributed to the uncertainties associated with accurately quantifying these factors. In addition, a large part of the remaining

  1. Gully monitoring at two locations in the Grand Canyon National Park, Arizona, 1996-2010, with emphasis on documenting effects of the March 2008 high-flow experiment

    USGS Publications Warehouse

    Schott, Nathan D.; Hazel, Joseph E.; Fairley, Helen C.; Kaplinski, Matt; Parnell, Roderic A.

    2014-01-01

    Many archeological sites in the Grand Canyon are being impacted by gully incision. In March 2008, a high-flow experiment (2008 HFE) was conducted with the intention of redistributing fine sediment (sand, silt, and clay) from the bed of the Colorado River to higher elevations along the channel margin. Deposition of fine sediment in gully mouths has been hypothesized to slow gully erosion rates and lessen impacts to archeological sites. The effects of the 2008 HFE on gullies were evaluated by comparing the topographic changes of three gullies at two study sites before and after the 2008 HFE. Comparison results indicated that sediment was deposited in gully mouths during the 2008 HFE, and that the inundated areas nearest to the river can be extensively altered by mainstream flow during high-flow events. Additionally, the history of gully evolution at the two study sites was examined between 1996 and 2010 and indicated that gullies have been subjected to thalweg incision and gully widening processes over a decadal timescale. Although the small sample size precludes extrapolating the results to other gullies, the findings contribute to the understanding of gully erosion in archeologically significant areas and have implications for future monitoring of gully erosion and evaluating the effectiveness of check dams intended to mitigate that erosion at archaeological sites in the Grand Canyon National Park.

  2. Lunar and Planetary Science XXXV: Mars: Gullies, Fluids, and Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Mars: Gullies, Fluids, and Rocks" included the following reports:Gullies on Mars and Constraints Imposed by Mars Global Surveyor Data; Gullies on Mars: Origin by Snow and Ice Melting and Potential for Life Based on Possible Analogs from Devon Island, High Arctic; Formation of Recent Martian Gullies by Avalanches of CO2 Frost; Martian Slope Streaks and Gullies: Origins as Dry Granular Flows; Depths and Geologic Setting of Northern Hemisphere Gullies (and Comparison to Their Southern Counterparts); Mars as a Salt-, Acid-, and Gas-Hydrate World; Composition of Simulated Martian Brines and Implications for the Origin of Martian Salts; Evaporation Rates of Brine on Mars; Hydrogeology of the Valles Marineris-Chaotic Terrain Transition Zone, Mars; Measured Fluid Flow in an Active H2O-CO2 Geothermal Well as an Analog to Fluid Flow in Fractures on Mars: Preliminary Report; Understanding Rock Breakdown on Earth and Mars: Geomorphological Concepts and Facet Mapping Methods; Classification and Distribution of Mars Pathfinder Rocks Using Quantitative Morphologic Indices; and Systematic Rock Classification in a Data-poor Environment: Application to Mars.

  3. Formation of Martian Gullies by the Flow of Simultaneously Freezing and Boiling Liquid Water

    NASA Technical Reports Server (NTRS)

    Heldmann, Jennifer L.; Mellon, Michael T.; Toon, Owen B.; Pollard, Wayne H.; Mellon, Michael T.; Pitlick, John; McKay, Christopher P.; Andersen, Dale T.

    2004-01-01

    Geomorphic evidence suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near the surface on Mars in geologically recent times. Irrespective of the ultimate source of the fluid carving the gullies, we seek to understand the behavior of this fluid after it reaches the Martian surface. We find that, contrary to popular belief, the fluvially-carved Martian gullies require formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water. Mars Global Surveyor observations of gully length and our modeling of water stability are consistent with gully formation from the action of pure liquid water that is simultaneously boiling and freezing.

  4. Morphological dynamics of gully systems in the subhumid Ethiopian Highlands: the Debre Mawi watershed

    NASA Astrophysics Data System (ADS)

    Zegeye, Assefa D.; Langendoen, Eddy J.; Stoof, Cathelijne R.; Tilahun, Seifu A.; Dagnew, Dessalegn C.; Zimale, Fasikaw A.; Guzman, Christian D.; Yitaferu, Birru; Steenhuis, Tammo S.

    2016-09-01

    Gully expansion in the Ethiopian Highlands dissects vital agricultural lands with the eroded materials adversely impacting downstream resources, for example as they accumulate in reservoirs. While gully expansion and rehabilitation have been more extensively researched in the semiarid region of Ethiopia, few studies have been conducted in the (sub)humid region. For that reason, we assessed the severity of gully erosion by measuring the expansion of 13 selected permanent gullies in the subhumid Debre Mawi watershed, 30 km south of Lake Tana, Ethiopia. In addition, the rate of expansion of the entire drainage network in the watershed was determined using 0.5 m resolution aerial imagery from flights in 2005 and 2013. About 0.6 Mt (or 127 t ha-1 yr-1) of soil was lost during this period due to actively expanding gullies. The net gully area in the entire watershed increased more than 4-fold from 4.5 ha in 2005 to 20.4 ha in 2013 (> 3 % of the watershed area), indicating the growing severity of gully erosion and hence land degradation in the watershed. Soil losses were caused by upslope migrating gully heads through a combination of gully head collapse and removal of the failed material by runoff. Collapse of gully banks and retreat of headcuts was most severe in locations where elevated groundwater tables saturated gully heads and banks, destabilizing the soils by decreasing the shear strength. Elevated groundwater tables were therefore the most important cause of gully expansion. Additional factors that strongly relate to bank collapse were the height of the gully head and the size of the drainage area. Soil physical properties (e.g., texture and bulk density) only had minor effects. Conservation practices that address factors controlling erosion are the most effective in protecting gully expansion. These consist of lowering water table and regrading the gully head and sidewalls to reduce the occurrence of gravity

  5. Gully development in Pavon Creeks: Downstream sediment supply and sub-basin restoration

    NASA Astrophysics Data System (ADS)

    Pearce, S.; McKee, L. J.

    2011-12-01

    Sediment supply in watersheds is a function of geology, climate, and land use. Small watersheds in the Coast Ranges of California can provide large volumes of sediment to downstream waterbodies due to the active tectonic setting, the Mediterranean climate, and the history of intense land use. The Pavon Creeks sub-basin, a 1.1 km2 tributary to Pinole Creek which drains to San Francisco Bay, California, currently provides a large supply of fine-grained sediment to the detriment of creek function and native species habitat. The sub-basin is situated near the active Hayward Fault Zone, is underlain by highly erosive shales and siltstones, and has experienced over 100 years of cattle grazing. Despite only comprising 3% of the total watershed area, the Pavon Creeks sub-basin has been identified as one of the largest sources of fine sediment within the Pinole Creek watershed. To protect creek function and habitat, watershed stakeholders have prioritized preventing excess fine sediment delivery to Pinole Creek. The sub-basin includes four small ephemeral gully channels that are primarily actively eroding, downcutting, and extending over their length, and secondarily aggrading over a shorter localized reach. Field-based geomorphic data including channel cross-sections, longitudinal profiles, bank pins, and headcut monitoring have documented channel incision, erosion, and lengthening of the channel network over six years. During Water Year 2006, the first and wettest year of measurements, we observed maximum rates of incision of 0.75 m, lateral bank erosion of 2.5 m, and gully extension of 16.3 m. Annual repeat surveys show continued gully evolution, and allowed for quantitative assessment of incision, aggradation, and extension rates over this time period, as well as eroded sediment volume. We found that the largest storm events of a season cause the greatest instantaneous amount of change in the sub-basin, but cumulative seasonal rainfall determines the total amount and

  6. Analysis of regional gullies within Noachis Terra, Mars: A complex relationship between slope, surface material and aspect

    NASA Astrophysics Data System (ADS)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2015-04-01

    The precise mechanisms by which martian hillside gullies erode and their dependence on the local environment remain subjects of debate. We studied three sharp rimmed craters in Noachis Terra and 37 gully profiles using Context Camera (CTX), Mars Orbiter Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC) data. We analysed the gully topographic profiles of seven gullies and nine dry ravines. We measured slope properties using HRSC elevation data and used thermal inertia to infer material types of the gully sites. We compared these with three nearby Noachian age craters possessing crater wall slope angles within the range of previously observed gully formations. In-line with previous findings on individual gullies, we found that the slope angles of gullies in our study area consistently reflect the inherited slope angles of the host escarpment, suggesting that traditional slope-based evidence of fluvial activity in martian gullies needs to be placed in context of its local environment. We also observed a direct relationship between gully morphology and local composition of surface units. Martian gully features, and possibly method of erosion appeared heavily influenced by changes in underlying geology and presence of erodible sediment. Examples included gully shape changing in accordance with type of erodible sediment. We suggest that the degraded rims of gully-free Noachian craters precluded slope angles high enough to trigger creation of precursors to alcoves through mass wasting. Lack of these hollows has probably prevented the accumulation of enough ice-rich sediment for gullies to form in. Our analysis reveals that there is a complex interdependence between slope processes and the local environment, and global martian gully models may not work at the local scale.

  7. Relationship between gullying and landslides within the Barlad Plateau, Romania

    NASA Astrophysics Data System (ADS)

    Niacsu, Lilian; Ionita, Ion

    2016-04-01

    Located in the eastern Romania and extending on 8200 km2 the Barlad Plateau is considered the most typical subunit of the Moldavian Plateau. The sedimentary Miocene-Pliocene clay-sandy layers, inter-bedded with shallow sandstone and limestone are gently dipping toward S-SE as homoclinal structure. Land degradation through soil erosion, gullying and landslides represent the most important environmental threat in the region. By using both the classical research methods such as repeated field surveys and mapping, mathematical-statistical processing as well as the present-day methods based on the GIS software it was possible to precisely measure and evaluate the gully erosion rates and triggered landslides during the last two centuries, especially with a very high accuracy since 1960. Results have indicated that the landslide development is strongly controlled by gullying. Generally, by combining the areal growth of both gullying and new landslides within the selected study catchments, it is noticeable that 62 % of the total recent land degradation occurred during the last 55 years, with the remainder pre-1960. In addition, half of the gully areal growth occurred since 1961 but the new triggered landslides amount over three-quarters of the total area under landslides. This asymmetrical distribution reveals that usually a preparing time lag of tens of years is required for triggering landslides by gullying and this pattern depicts the common mechanism for landslide development. Acknowledgements: This work was partly supported by a grant from the Romanian National Authority for Scientific Research, CNDI-UEFISCDI, Project number PN-II-PT-PCCA-2011-3.2-0975.

  8. Gully evolution and geomorphic adjustments of badlands to recent afforestation

    NASA Astrophysics Data System (ADS)

    Ballesteros-Cánovas, Juan Antonio; Stoffel, Markus; Francisco Martín-Duque, Jose; Corona, Christophe; Lucia, Ana; María Bodoque, Jose

    2016-04-01

    Badlands and gullied areas are among the geomorphic environments with the highest erosion rates worldwide, however records on their evolution are very scarce and often limited to presumed initial conditions and the known present state. In this communication, we present a unique and very dense and annual record and outstanding example of erosion processes in a Mediterranean environment in Central Spain, where badland and gullying processes on sandy slopes of a set of mesas have been presumably triggered by quarrying activities since Medieval times. The gully channel evolution here analyzed provides an exceptional example of a larger setting of geomorphic. Besides the analysis of geomorphic adjustments to historical land-use changes induced by historical quarrying and gullying dynamics, we also quantified the impact of current geomorphic adjustments to 20th century afforestation by combining multiproxy such as aerial photography, historical archives, and large dataset of exposed roots to date, quantify, and reconstruct the morphology of a rapidly evolving channel in a gullied catchment. In this analysis, more than 150 exposed roots were analyzed to quantify and report channel incision; widening and gully retreatment rates during the last decades, as well as to quantify sheet erosion on different soil units. Our results suggest that, rather than stabilizing gully evolution, the afforestation carried out during 1960s has played an important role in water-sediment balance and connectivity and would have triggered the initiation of channel incision processes in the 1980s. Therefore, we observe that the channel incision match with a significant increase of the vegetation cover, which leads a significant decrease in sheet erosion rates. Based on our long-term annual gully reconstruction, we observed that sediment delivery does not correlate with the estimated intensity of precipitation (Fourier index). Instead, we observe abrupt morphological changes in the gully are

  9. Assessment of hydrological controls on gully formation near Lake Tana, Northern Highlands of Ethiopia

    NASA Astrophysics Data System (ADS)

    Tebebu, T. Y.; Abiy, A. Z.; Dahlke, H. E.; White, E. D.; Collick, A. S.; Steenhuis, T. S.

    2008-12-01

    For the past five decades, gully erosion has been one of the dominant degradation processes in the Ethiopian Highlands. Gully erosion negatively affects soil resources, lowers soil fertility in intergully areas, reduces the pastureland available for livestock, and aggravates siltation of reservoirs. Assessing the location and rate of gully development and changes in the controlling factors (climate, soil, hydrology and land cover) of gully erosion will help explain the faced acceleration in land degradation. The study was performed in a gully system in the 800 ha Debre-Mewi watershed south of Bahir Dar, Amhara region, Ethiopia. Analyses comprised monitoring gully development through profile measurements, air photograph interpretations, and semi-structured interview techniques. Gully hydrological processes were investigated based on measurements of gully runoff and water levels in 24 piezometers in the gully contributing area. The Debre-Mewi gully is a still actively eroding gully system. A comparison of the gully area estimated from a 0.5 m resolution Quickbird image with the current gully area, walked with a Garmin GPS, showed that the eroded gully area increased by 30% from 0.51 ha in 2005 to 0.735 ha in 2008. Based on measurements of several gully cross-sections an approximate gully volume of 7985 m3 could be estimated. Using the watershed area of the gully system of 14.29 ha and an average gully erosion rate of 24.8 t ha-1 a- 1 could be estimated. Gully erosion rates accelerated since 1991 through the increased degradation of the vegetation cover and clearance of the indigenous vegetation on the hillsides, leading to an increase of surface and subsurface runoff from the hillsides to the wet valley bottoms. Gully heads retreat into the hillslope through concentrated runoff during the rainy season erodes existing soil pipes and cracks in the vicinity of the gully head and banks. The formation of subsurface soil pipes is likely triggered through abrupt changes in

  10. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds.

  11. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds. PMID:21216098

  12. Regulation of muscle sympathetic nerve activity after bed rest deconditioning

    NASA Technical Reports Server (NTRS)

    Pawelczyk, J. A.; Zuckerman, J. H.; Blomqvist, C. G.; Levine, B. D.

    2001-01-01

    Cardiovascular deconditioning reduces orthostatic tolerance. To determine whether changes in autonomic function might produce this effect, we developed stimulus-response curves relating limb vascular resistance, muscle sympathetic nerve activity (MSNA), and pulmonary capillary wedge pressure (PCWP) with seven subjects before and after 18 days of -6 degrees head-down bed rest. Both lower body negative pressure (LBNP; -15 and -30 mmHg) and rapid saline infusion (15 and 30 ml/kg body wt) were used to produce a wide variation in PCWP. Orthostatic tolerance was assessed with graded LBNP to presyncope. Bed rest reduced LBNP tolerance from 23.9 +/- 2.1 to 21.2 +/- 1.5 min, respectively (means +/- SE, P = 0.02). The MSNA-PCWP relationship was unchanged after bed rest, though at any stage of the LBNP protocol PCWP was lower, and MSNA was greater. Thus bed rest deconditioning produced hypovolemia, causing a shift in operating point on the stimulus-response curve. The relationship between limb vascular resistance and MSNA was not significantly altered after bed rest. We conclude that bed rest deconditioning does not alter reflex control of MSNA, but may produce orthostatic intolerance through a combination of hypovolemia and cardiac atrophy.

  13. South Mid-latitude Gullies

    NASA Technical Reports Server (NTRS)

    2005-01-01

    19 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows deep gullies cut into the wall of a south mid-latitude crater. Erosion has exposed layers in the upper wall of the crater; it is possible that groundwater seeping through a layer or layers in the wall led to the genesis of the gullies. The banked nature of the gully channels suggests that a liquid was involved.

    Location near: 35.5oS, 194.8oW Image width: width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Spring

  14. Martian gullies as seen by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)

    NASA Astrophysics Data System (ADS)

    Barnouin-Jha, O. S.; McGovern, A.; Buczkowski, D.; Seelos, K.; Seelos, F.; Murchie, S.; Ehlmann, B.; Science Team, C.

    2008-12-01

    Over 100 high resolution targeted images of martian gullies and debris fans have been obtained by the CRISM instrument currently orbiting Mars aboard the Mars Reconnaissance Orbiter. A survey of these images provides some new constraints on the origin and evolution of these features. We have found no evidence for the recent formation of hydrated minerals in these features, even the most recent light-toned ones. Ice clouds are sometimes visible in the vicinity of the gullies, but these are seasonal. A wide range of mineralogies is observed and includes phyllosilicates, mafics and sulphates. The distribution of the minerals and their relationship to the underlying rocks suggest that the gully-forming process exposes underlying rocks and moves them downslope. When more than one gully is present on a given slope, both vertical and horizontal stratigraphy within the source region is revealed. The wispy nature of the deposits, especially when specific spectral indicators are examined, suggests that the gullies are the result of many small events. The lack of dust coverage on some of the spectrally distinct gullies could indicate fairly recent activity, although eolian erosion could also be a factor. Many other gullies that are indistinct spectrally from their surroundings could be old and inactive, or could indicate very active dust deposition. The processes dominating the modification of the gullies can be established by combining CRISM observations with other nearby geomorphic indicators.

  15. A complicated story of frost and wind: Present-day gully activity within the north polar erg, Mar

    NASA Astrophysics Data System (ADS)

    Diniega, Serina; Hansen, Candice; Allen, Amanda; Grisby, Nathan; Li, Zheyu Joey

    2016-10-01

    Analyses of high-resolution observations have shown that the dunes within the martian north polar erg (AKA Olympia Undae) are currently very active on seasonal and yearly timescales, with 20-60% of the dunes within five polar dune fields undergoing the formation of alcove-apron features each Mars year. Previous studies have hypothesized formation mechanisms, based on observations of when new alcove and alcove-apron features form within an individual field through one Mars year. However, results are ill-constrained (and thus different hypotheses have been proposed) as the polar hood and winter night mean very few images are taken during the actual period of activity. In this study, we mitigate this limitation by examining several fields over several Mars years -- thus bringing aggregated results as well as detailed correlation checks against environmental conditions and seasonal processes to bear on the problem. From this, we propose a new process that appears consistent with all observations: (1) small alcoves form along the dune brink in the autumn (under the polar hood) due to instabilities induced by the night-formation and morning-sublimation of frost. As autumn progresses, the seasonal frost layer builds over the altered dune slope. (2) In the early spring, sublimation activity is concentrated and/or enhanced over these alcoves, causing further erosion and the formation of larger alcove-apron features. From the planform dimensions of the newly formed alcoves, we can estimate the volume of sand moved down the dune slope during one period of activity and estimate the aeolian sediment flux by looking at how quickly the alcoves are erased. We find that, over a Mars year, the amount of material moved via alcove-apron activity and via the wind are both comparable to aeolian sand flux estimates over dunes within lower-latitude regions of Mars. Thus it appears that the formation of alcoves-aprons is a significant mechanism for dune advancement and evolution within the

  16. Comparing the topographic long profiles of gullies on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Conway, Susan; Balme, Matthew; Murray, John; Towner, Martin

    2014-05-01

    Liquid water is not stable under the present atmospheric conditions on the martian surface. Hence, the discovery of widespread recently active kilometre-scale gullies that resemble those carved by water on Earth [1,2], was extremely surprising. Some authors suggest that either carbon dioxide driven processes or dry mass wasting could explain these features [3-6]. However, recent work has shown that some aspects of gully-morphology, such as braiding and streamlined features, are hard to explain with these mechanisms [e.g., 7,8]. In this study we have used topographic long profiles to investigate the formation mechanism of martian gullies. On Earth it is recognised that certain forms of long-profiles can be linked to a particular process, for example, at equilibrium fluvial systems have a profile curve of exponential decay [9]. However, these shapes have not been generalised for kilometre-scale landforms, such as gullies. We used differential GPS data and airborne laser altimeter data on Earth (LiDAR) from NSA-funded NCALM and UK's NERC ARSF to generate profile-data for gullies with a fluvial and debris flow origin. On Mars we used stereo-images from the HiRISE camera (25 cm/pix) and generated the gully-profiles using the manual point-matching method of Kreslavsky [10]. We found that the shape of gully long profiles on Mars is similar to that of both fluvial and debris flow gullies on Earth. However, more of the martian gullies we have studied are similar to fluvial gullies than to debris flow gullies. The slopes of the gully long profiles on Mars tend to be shallower than fluvial gullies on Earth, but this can be accounted for by the difference in gravity between Earth and Mars. References cited: [1] M.C. Malin and K.S. Edgett, Science, (2000), 288,2330-2335.[2] M.C. Malin et al., Science, (2006), 314,1573-1577. [3] T. Shinbrot et al., Proc Natl Acad Sci U A, (2004), 101,8542-8546. [4] S. Diniega et al., Icarus, (2013), 225,526-537. [5] T. Ishii and S. Sasaki, Lunar

  17. Understanding Gully Formation and Seasonal Flows on Recent and Current Mars

    NASA Astrophysics Data System (ADS)

    Gulick, Virginia C.; Glines, Natalie

    2016-10-01

    The discoveries of gullies and seasonal slope flows (RSL) have re-ignited the debate over various channel, valley, and gully formation mechanisms on Mars. The controversy over whether liquid water was involved with gully formation, harkens back to the mid-1970s to early 2000s, where catastrophic flooding, surface runnoff and ground-water sapping processes were strongly debated along with other mechanisms as the primary processes responsible for channel and valley formation on Mars. However, over the past decade, the value of multiple working hypotheses has again become apparent, this time in understanding the formation of Martian gullies and Recurring Slope Lineae. Various mechanisms put forth to explain these landforms include liquid H2O/ice erosion, CO2 ice/frost sublimation, CO2 ice block sliding, water and brine flows, salt deliquescence, and dry granular flows, among others.We carried out detailed morphologic/morphometric studies of gullies in various environmental settings on Mars to evaluate the potential formation processes. Using HiRISE images and DTMs, we mapped and generated detailed longitudinal and cross-sectional profiles of gully systems and estimated volumes for both the gullies and their debris aprons. Several gullies form highly integrated patterns similar to fluvial systems. Additionally, RSL are often found either in the tributaries of these integrated systems or in adjacent regions, implying that RSL may play a role in initiating gully formation or mark the last vestiges of water activity in these locations. We also find that the more highly integrated gullies have volumes significantly larger than their aprons, suggesting that the missing volumes (~40-60% or more) were likely the volatiles involved in gully formation. Additionally, THEMIS and TES surface temperatures of these integrated gully sites, many of which also contain RSL, are at or above freezing seasonally suggesting that the volatile component may be consistent with H2O although CO2

  18. Long-term monitoring of martian gully formation and evolution with MRO/HiRISE

    NASA Astrophysics Data System (ADS)

    Dundas, Colin M.; Diniega, Serina; McEwen, Alfred S.

    2015-05-01

    Gully landforms are commonly taken as evidence for surface liquid water in the recent geological history of Mars. Repeat observations with the High Resolution Imaging Science Experiment (HiRISE) instrument on the Mars Reconnaissance Orbiter demonstrate widespread activity in gullies in the southern hemisphere, particularly in those with the freshest morphologies. This activity includes substantial channel incision and large-scale mass movements, and constitutes ongoing gully formation rather than degradation of older landforms. New apron deposits that are bright, dark and neutrally toned have all been observed. The timing of gully activity is seasonally controlled and occurs during the period when seasonal frost is present and defrosting. These observations support a model in which currently active gully formation is driven mainly by seasonal CO2 frost. Gullies in the northern hemisphere are far less active than those in the south. This may be due to the current timing of perihelion near the northern winter solstice. Integrated over time, activity like that observed within the past few years appears capable of forming all of the martian gully landforms on timescales of millions of years. Additionally, the current style and rate of activity is able to erase meter- to decameter-scale surface features that might have been uniquely produced by other processes during the last obliquity high ∼0.4 Ma. Although it is impossible to rule out a past role for water in the formation of martian gullies, a model in which gullies form only through currently active processes with little or no liquid water is consistent with our observations.

  19. South High-latitude Gullies

    NASA Technical Reports Server (NTRS)

    2006-01-01

    1 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of gullies on a scarp in Lyell Crater.

    Location near: 69.7oS, 14.0oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  20. Present-day formation and seasonal evolution of linear dune gullies on Mars

    NASA Astrophysics Data System (ADS)

    Pasquon, Kelly; Gargani, Julien; Massé, Marion; Conway, Susan J.

    2016-08-01

    Linear dune gullies are a sub-type of martian gullies. As their name suggests they only occur on sandy substrates and comprise very long (compared to their width) straight or sinuous channels, with relatively small source areas and almost non-existent visible deposits. Linear dune gullies have never been observed on terrestrial dunes and their formation process on Mars is unclear. Here, we present the results of the first systematic survey of these features in Mars' southern hemisphere and an in-depth study of six dunefields where repeat-imaging allows us to monitor the changes in these gullies over time. This study was undertaken with HiRISE images at 25-30 cm/pix and 1 m/pix elevation data derived from HiRISE stereo images. We find the latitudinal distribution and orientation of linear dune gullies broadly consistent with the general population of martian gullies. They occur predominantly between 36.3°S and 54.3°S, and occasionally between 64.6°S and 70.4°S. They are generally oriented toward SSW (at bearings between 150° and 260°). We find that these gullies are extremely active over the most recent 5 Martian years of images. Activity comprises: (1) appearance of new channels, (2) lengthening of existing channels, (3) complete or partial reactivation, and (4) disappearance of gullies. We find that gully channels lengthen by ∼100 m per year. The intense activity and the progressive disappearance of linear dune gullies argues against the hypothesis that these are remnant morphologies left over from previous periods of high obliquity millions of years ago. The activity of linear dune gullies reoccurs every year between the end of winter and the beginning of spring (Ls 167.4°-216.6°), and coincides with the final stages of the sublimation of annual CO₂ ice deposit. This activity often coincides spatially and temporally with the appearance of recurrent diffusing flows (RDFs)-digitate-shaped, dark patches with low relative albedo (up to 48% lower than the

  1. Gully development processes in the Ethiopian Highlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gully erosion is an important soil degradation process in a range of environments, causing considerable soil losses and producing large volumes of sediment. In Ethiopia, gully erosion is a major problem expanding at alarming rate and devastating cultivated and grazing lands. The objective of the stu...

  2. Integrated approaches to restore gullies in land prone to soil piping: innovations from the drylands of northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Deckers, Jozef; Moulaert, Lys; Van Damme, Alexander; Haile, Mitiku; Poesen, Jean; Nyssen, Jan

    2014-05-01

    Multiple on-site and off-site effects of gully erosion threaten sustainable development, which is especially evident in dryland environments. To control soil erosion by gullying, various soil and water conservation measures have been developed, of which check dams are the most common. Where soil piping occurs, soil and water conservation measures have limited effect on gully stabilization, and check dams easily collapse. Therefore, new integrated approaches are needed to control gully erosion induced by soil piping. Here, a subsurface geomembrane dam is proposed as an innovative measure to reduce subsurface flow in soil pipes near gullies. Application of such a dam in Northern Ethiopia, resulted in a decrease of gully erosion rates in Vertisols, and a rising water table in the intergully areas near the gully channel. The consequence of this effect for agriculture near gully channels is the reduction of soil desiccation and hence, increased crop yields in the intergully areas near the gully channels. With the gully filling and stabilizing, runoff water could be diverted into adjacent land, offering additional benefits to the local communities. Here, the runoff diversion was done into a vegetation protection site, in order to enhances biomass production, especially tree growth. Moreover, a water collection pound was created to make water available in the prolonged dry season. These interventions support additional economical activities such as beekeeping and the establishment of a tree nursery. With the multiple on-site and off-site benefits of the integrated approach, local communities have a better guarantee of investment return and livelihood improvement, increasing their support to gully rehabilitation schemes. Keywords: Crop, Subsurface dam, Soil and water conservation, Tree growth, Vertisol, Dryland.

  3. The formation and evolution of youthful gullies on Mars: Gullies as the late-stage phase of Mars’ most recent ice age

    NASA Astrophysics Data System (ADS)

    Dickson, James L.; Head, James W.

    2009-11-01

    Gullies are extremely young erosional/depositional systems on Mars that have been carved by an agent that was likely to have been comprised in part by liquid water [Malin, M.C., Edgett, K.S., 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330-2335; McEwen, A.S. et al., 2007. A closer look at water-related geologic activity on Mars. Science 317, 1706-1709]. The strong latitude and orientation dependencies that have been documented for gullies require (1) a volatile near the surface, and (2) that insolation is an important factor for forming gullies. These constraints have led to two categories of interpretations for the source of the volatiles: (1) liquid water at depth beneath the melting isotherm that erupts suddenly ("groundwater"), and (2) ice at the surface or within the uppermost layer of soil that melts during optimal insolation conditions ("surface/near-surface melting"). In this contribution we synthesize global, hemispheric, regional and local studies of gullies across Mars and outline the criteria that must be met by any successful explanation for the formation of gullies. We further document trends in both hemispheres that emphasize the importance of top-down melting of recent ice-rich deposits and the cold-trapping of atmospherically-derived H 2O frost/snow as important components in the formation of gullies. This provides context for the incorporation of high-resolution multi-spectral and hyper-spectral data from the Mars Reconnaissance Orbiter that show that (1) cold-trapping of seasonal H 2O frost occurs at the alcove/channel-level on contemporary Mars; (2) gullies are episodically active systems; (3) gullies preferentially form in the presence of deposits plausibly interpreted as remnants of the Late Amazonian emplacement of ice-rich material; and (4) gully channels frequently emanate from the crest of alcoves instead of the base, showing that alcove generation is not necessarily a product of undermining and

  4. Debris Flow as a Mechanism for Forming Martian Gullies

    NASA Astrophysics Data System (ADS)

    Conway, S. J.; Balme, M. R.; Murray, J. B.; Towner, M. C.

    2009-04-01

    The current low temperatures and pressures at the martian surface are not conducive to the stability of liquid water; hence the discovery of recently active, fluvial-like gullies [1, 2] presents an apparent paradox: how can these fluvial landforms have occurred if water is not stable at the surface? To approach this problem we have compared the morphometric properties of gullies in various settings on Earth to those of gullies on Mars. We have measured debris flows in Westfjords, Iceland [3] and gullies in La Gomera, Canary Islands [4]. The Iceland elevation data were generated from differential GPS and a LiDAR survey, and the La Gomera data from differential GPS. In addition we used elevation data from the Shuttle Radar Topography Mission (SRTM) extracted along previously mapped debris flows in the Taurids Mountains, Turkey [5] and the Colorado Front Range, USA [6]. We have compared these data to preliminary analyses of stereo HiRISE images of martian gullies in four locations using a method to extract point elevation data developed by Kreslavsky [7]. In all cases the elevation along the centre channel of the debris flow or gully was used for comparison to Mars. For Iceland and La Gomera we also extracted cross-profiles for comparison with martian gullies. Simply comparing the longitudinal profiles of gullies on Mars and different situations on the Earth highlights the variability between debris flow sites on Earth. The martian gully profiles are most similar to debris flows in the Taurids Mountains and in the Colorado Front Range. The overall slope is shallower on Mars compared to the Iceland debris flows and the ephemeral water flow gullies in La Gomera. The runout or total length of gullies is also more variable and greater for Mars than for Iceland and La Gomera. Caution should be taken in interpreting the cross profiles for Mars as the error on the elevation is at least 1m and there is low sampling density in comparison to the other datasets. The v-shaped La

  5. Morphostructural context of gullies in Taroudant, Morocco

    NASA Astrophysics Data System (ADS)

    Hssaine, Ali Ait; Ghafrani, Hassan; Peter, Klaus Daniel; d'Oleire-Oltmanns, Sebastian; Ries, Johannes B.; Marzolff, Irene

    2013-04-01

    The Souss depression is wedged between the High Atlas to the north and the Anti-Atlas to the south. It corresponds to the south atlasic path and opens on the Atlantic Ocean. It is drained by the Souss wadi which flows into the ocean. This depression extends over 160 km in length from east to west and 40 km wide from north to south, its greatest extension is near the city of Taroudant. Morphologically, the Souss depression is a set of coalescing alluvial fans from the High Atlas and Anti-Atlas, their convergence is highlighted by the Souss or the very low Holocene terrace. Morphostructurally, the Souss depression is a broad Cretaceous syncline fault, filled with Plio-Quaternary deposits whose thickness can reach about 250 to 300 m near Taroudant. These deposits are in a stepped or inserted position at the outlets of the wadis of the Atlas area and contain coarse material. They become thin and layered (stacked) in the distal part of alluvial fans in the axis of the syncline due to subsidence. These superficial deposits of Holocene age support a speculative agriculture and are heavily used by large agricultural investors. Currently, at the historic town of Taroudant and around the Wadi el Ouaar, on these superficial deposits (sand, silt and clay) grows a spectacular landscape of gullies moving in all directions and leading to land abandonment. Two factors are responsible for triggering these gullies: the first is of tectonic order. It is linked to a hidden fault and active which affects the Cretaceous base. Its influence is expressed by the behaviour of the river system (deep-set of Wadi el Ouaar, dissymmetry of the morphological fan of Assif Irguitène). The second is the human factor, related to the introduction of sugar cane and its factories in Taroudant and in the Souss region in the 16th century (deforestation of the argan tree).

  6. Multi-agent gully processes: Evidence from the Monaro Volcanic Province, Australia and in Terra Cimmeria, Mars

    NASA Astrophysics Data System (ADS)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.; Roach, Ian C.

    2016-03-01

    Comparison of the similarities and differences between terrestrial and Martian hillside gullies promotes understanding of how surface processes operate on both planets. Here we tested the viability of subsurface flow of water as a process affecting gully evolution. We compared gullies within the Monaro Volcanic Province near Cooma, New South Wales, Australia, to gullies possessing strong structural control near Gasa Crater, Terra Cimmeria, Mars. Although cursory examination of the Monaro gullies initially suggested strong evidence for aquifer erosion, detailed field surveys showed the evidence to be ambiguous. Instead a complex regime of erosion dependent on multiple conditions and processes such as local geology, surface runoff, dry mass wasting, and animal activity emerged. We found the morphology of gullies near Gasa Crater to be consistent with erosion caused by liquid water, while also being heavily influenced by the local environment, including slope and geology. Additionally, erosion at the Martian site was not consistent with evidence of subsequent, smaller scale erosion and channel modification by dry mass wasting. Local conditions thus play an important role in gully evolution, further highlighting that processes forming Martian gullies may be more diverse than initially thought.

  7. Martian Gullies and Groundwater: A Series of Unfortunate Exceptions

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2005-01-01

    Gullies are commonly inferred to represent debris flows, lubricated and carried by liquid water that flowed from underground. The inference of groundwater, based principally on the apparent initiation of gullies at specific bedrock layers, has not been considered for consistency with local geology. Here, I examine gully occurrences for: presence of impermeable layers (aquicludes) in the subsurface, that the layers not tilt away from the gully-bearing walls, and that liquid water could have been available at or above the gully elevations.

  8. Insight into gully formation on Mars with CRISM on the Mars Reconnaissance Orbiter

    NASA Astrophysics Data System (ADS)

    Nunez, J. I.; Barnouin, O. S.; McGovern, A.; Seelos, F. P.; Seelos, K. D.; Buczkowski, D.; Murchie, S. L.

    2013-12-01

    Gullies are widespread on Mars, with most occurrences found in the southern hemisphere. Indicative of recent downslope movement, multiple alternative models have been proposed for their formation, including groundwater release, melting of snow or near-surface ground ice, dry granular flows, or different CO2-lubricated flows. Ongoing morphological changes to gully channels and aprons observed with the High Resolution Imaging Science Experiment (HiRISE) over intervals as short as one Martian year have indicated seasonal activity consistent with models for gully formation driven by CO2 frost sublimation as well as dry granular flow. To determine if compositional information could provide additional insight into the mechanics of gully formation and seasonal activity, we have analyzed over 100 images of gullies and their apron deposits taken with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) over multiple Martian years. Newly processed prototype Map-projected Targeted Reduced Data Record (MTRDR) hyperspectral image cubes were used to identify and extract spectral information. Additional Mars Orbital Laser Altimeter (MOLA) and HiRISE DTM data were used to obtain topographical information. Most gullies observed are spectrally indistinct from their surroundings, most likely due to dust coatings. Where spectral contrast was observed, gullies predominantly exposed and transported underlying mafic material downslope. Rarely were hydrated minerals or alteration products observed in place within these gullies or within their apron deposits, indicating very limited chemical reaction with liquid water. Where detected, hydrated minerals include phyllosilicates and sulfates, and usually occur in a pre-existing layer that is exposed and subsequently transported downslope. Gullies do not show evidence for in situ precipitation or alteration as a result of long lived water-rock interactions. Finally, spectral evidence for

  9. The processes and timing of sediment delivery from headwaters to the trunk stream of a Central European mountain gully catchment

    NASA Astrophysics Data System (ADS)

    Larsen, Annegret; Bork, Hans-Rudolf; Fuelling, Alexander; Fuchs, Markus; Larsen, Joshua R.

    2013-11-01

    Gully systems determine downstream water quality and sediment loads since they are located where streams begin. They are often only considered as a sediment source, and the degree to which gully systems also store sediment, and the timescales of this storage, have received less attention. Gully sediment storage is important because many sedimentary archives, such as floodplains and lakes, have recorded increases in sedimentation rates particularly in Medieval times, which are interpreted as the result of increased slope erosion and gully activity. At present there is insufficient evidence directly linking such other sedimentary archives and gully systems. There is also a lack of long term records which may indicate how the major external controls, climatic or anthropogenic, might determine gully responses. To address this, we analysed sediment sources and sinks within a small (43 ha) gully catchment in the Spessart Mountains, Germany. We found five main phases of erosion and deposition since ~ 13 ka, which revealed catchment vegetation significantly controlled geomorphic responses. A loss of vegetation due to climate deterioration (e.g. Younger Dryas) or deforestation (e.g. Medieval period) caused widespread slope instability and the aggradation of the gully thalweg. In contrast, well forested conditions before the Medieval period, and again in recent years, re-stabilised the slopes, leading to gully incision with knickpoint retreat. This result differs from previous interpretations of gully activity in Central Europe that gully erosion mostly occurred in Medieval times. Our results also demonstrate that only the initial phase of knickpoint retreat is significant for supplying sediment to the gully fan and trunk stream. Then knickpoint retreat leads to a relative increase in the thalweg storage capacity downstream, which limits further sediment export. This has important implications for the interpretation of floodplain ages, since the initial supply of gully

  10. Effects of ephemeral gully erosion on soil degradation in a cultivated area in Sicily

    NASA Astrophysics Data System (ADS)

    La Spada, Carmelo; Capra, Antonina; Gelsomino, Antonio; Ollobarren del Barrio, Paul

    2015-04-01

    Water erosion is the main cause of soil degradation on cultivated lands under Mediterranean climate. In this conditions, gully erosion is a major contributor to loss of soil productivity due to the big amounts of soil removed from the most productive top-layer. However, only few studies on the effects of gully erosion and artificial controlling measures on soil degradation are available. The study analyzes the effects of the ephemeral gully erosion and infilling by tillage operations on several physical-chemical soil properties influencing the soil productivity. The study area is located in the center of Sicily, in an agricultural context characterized by ephemeral gully erosion. Five fields with different crops and soil characteristics affected by this type of erosion were selected. Currently, local farmers adopt the artificial measure to gully filling activities to control gully erosion and continue the same agricultural management practice. Therefore, the studied ephemeral gullies show a cyclic behavior. They appear during the rainy season, are erased from July to October by soil infill from areas adjacent to the channel using ordinary tillage equipment, and, in most years, they reappear in the same position during the following rainy season. For each situation, 20 samples were taken, located on 5 transects in the direction perpendicular to the ephemeral gully, in specific positions: 2 outside the erosive channel (one in the valley-deposit area and one upstream of the basin in the undisturbed area), and 3 along the same. For each transect, the samples were collected in 4 different positions: one inside the ephemeral gully, the other 3 in external points spaced to represent the areas affected by the annual process of erosion and infilling of the gully. For each sample, a set of the main chemical and physical soil characteristics which influence the soil fertility were determined: particle size, pH, electrical conductivity, total content of carbonates, nitrates

  11. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    USGS Publications Warehouse

    Sankey, Joel B.; Draut, Amy E.

    2014-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian–hillslope–fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic–ecologic interactions in determining arid-landscape evolution.

  12. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Sankey, Joel B.; Draut, Amy E.

    2014-09-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian-hillslope-fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic-ecologic interactions in determining arid-landscape evolution.

  13. Accurate, low-cost 3D-models of gullies

    NASA Astrophysics Data System (ADS)

    Onnen, Nils; Gronz, Oliver; Ries, Johannes B.; Brings, Christine

    2015-04-01

    Soil erosion is a widespread problem in arid and semi-arid areas. The most severe form is the gully erosion. They often cut into agricultural farmland and can make a certain area completely unproductive. To understand the development and processes inside and around gullies, we calculated detailed 3D-models of gullies in the Souss Valley in South Morocco. Near Taroudant, we had four study areas with five gullies different in size, volume and activity. By using a Canon HF G30 Camcorder, we made varying series of Full HD videos with 25fps. Afterwards, we used the method Structure from Motion (SfM) to create the models. To generate accurate models maintaining feasible runtimes, it is necessary to select around 1500-1700 images from the video, while the overlap of neighboring images should be at least 80%. In addition, it is very important to avoid selecting photos that are blurry or out of focus. Nearby pixels of a blurry image tend to have similar color values. That is why we used a MATLAB script to compare the derivatives of the images. The higher the sum of the derivative, the sharper an image of similar objects. MATLAB subdivides the video into image intervals. From each interval, the image with the highest sum is selected. E.g.: 20min. video at 25fps equals 30.000 single images. The program now inspects the first 20 images, saves the sharpest and moves on to the next 20 images etc. Using this algorithm, we selected 1500 images for our modeling. With VisualSFM, we calculated features and the matches between all images and produced a point cloud. Then, MeshLab has been used to build a surface out of it using the Poisson surface reconstruction approach. Afterwards we are able to calculate the size and the volume of the gullies. It is also possible to determine soil erosion rates, if we compare the data with old recordings. The final step would be the combination of the terrestrial data with the data from our aerial photography. So far, the method works well and we

  14. Sediment yield and connectivity in a gullied sandy catchment

    NASA Astrophysics Data System (ADS)

    Lucía, Ana; Francisco Martín-Duque, José; Laronne, Jonathan B.; Ángel Sanz-Santos, Miguel

    2014-05-01

    Badland areas are considered to have high connectivity of sediment at the catchment scale; however, little is known about processes occurring in gullies and badlands developed in sands. This type of gullies is quite common in the Central-Eastern Iberian Peninsula and is associated with historic mining. The sandy badlands also appear in both abandoned and traditionally reclaimed mines, generating on- and offsite environmental effects. Our aim is to quantify the rates of the different processes occurring in the sandy gullied catchments, as well as their coupling and connectivity at a catchment scale. This may allow application to improve reclamation practice in mines and quarries located in sandy materials. The study site is a small (1.32 ha) gullied catchment, the Barranca de los Pinos, which is located in the Northern Piedmont of the Guadarrama Mountains (Central Spain). The catchment area has been divided into Homogeneous Response Units (HRUs) attending to the dominant active process . The sediment produced in the different HRUs has been monitored by a variety of methods: repeat Terrestrial Laser Scanning of high gradient slopes, closed microplots in low gradient slopes and automatic (Reid type) slot bedload samplers and siphon samplers to monitor suspended sediment transport in the channel. During the 2010-11 monitoring period the sediment yield due to gravitational movements in high gradient slopes varied from 20 to 200 kg m-2y-1. In the low gradient slopes the splash and non-concentrated runoff generated 0.1 - 6 kg m-2y-1,while the channel yielded 7.44 ± 1.08 kg m-2y-1 with a very high proportion (>70%) of bedload. Despite the difficulties of extrapolating and comparing the results obtained at different spatial and temporal resolutions, annual patterns of erosion and transport of sediments within the sandy gullied catchments have been identified. These confirm that the transport of sediment in this catchment is limited by the capacity of flow events to

  15. Reconciling historical and contemporary evidence of aeolian-based, gully annealing processes in Glen, Marble, and Grand Canyon, USA

    NASA Astrophysics Data System (ADS)

    Sankey, J. B.; Draut, A. E.

    2013-12-01

    In the absence of large Colorado River floods in Glen, Marble, and Grand Canyons since the completion of Glen Canyon Dam, the geomorphic process most able to counteract the effects of gully incision on terraces and slopes above the contemporary active Colorado River channel is aeolian sand transport that can partially or entirely fill (anneal) small gullies. Whereas gully-formation processes have been much studied, relatively little is known about processes of gully annealing. Aeolian-based annealing has been observed in several instances in the modern Colorado River corridor operating on time scales of months. However, individual, short-term occurrences of aeolian deposition that counteract gully erosion have not yet been expanded into a landscape-scale evaluation of the prevalence of gully-annealing processes over longer time scales (years-decades) along the post-dam corridor. The extent that aeolian or other annealing processes might slow, or temporarily reverse, gully incision and erosion is important in this system because of the propensity for erosion damage to locations of cultural significance that are extensive on terraces and slopes above the contemporary active Colorado River channel. Moreover, the reduction of mainstem fluvial sediment inputs to the system since completion of Glen Canyon Dam might impact the potential of aeolian redistribution of Colorado River-derived sediment as an effective gully annealing mechanism on upper slopes and terraces. We present an investigation of the extent that observations of (i) historical annealing and (ii) contemporary annealing potential, reconcile with (iii) literature and/or model-based estimates of relative rates of gully formation and aeolian deposition in this system. The central question of this work is whether these complimentary lines of evidence support aeolian infilling as a viable mechanism for annealing gullies in Glen, Marble, and Grand Canyons, and analogous systems. We examine the evidence for

  16. Slope Gullies on Devon Island, Canadian Arctic: Possible Analogs for Gullies on Mars and Evidence for Recent Transient Environmental Change on Mars.

    NASA Astrophysics Data System (ADS)

    Lee, P.

    2002-12-01

    The origin and evolution of the relatively youthful slope gully features on Mars first reported by Malin and Edgett (2000) remain enigmatic. Two prevailing hypotheses concerning their formation involve the discharge of subsurface H2O at the gully sites: groundwater seepage (1) and/or the melting of ground-ice (2, 3). In the course of geologic field investigations on Devon Island, Canadian Arctic, we have identified morphologic and contextual analogs for the martian gullies that result from a radically different mechanism of formation (4). The gullies on Devon result mainly from the episodic melting of transient surface snow and ice deposits, with little contribution from subsurface H2O reservoirs. Timescales for gully formation on Devon Island are ­š104 years (5). The gullies on Devon suggest that the formation of gully features on Mars might not necessarily have involved discharges of subsurface H2O at the gully sites. Instead, gullies on Mars might be the result of transient surface snow and ice melting, which in turn might be the result of short-term changes in regional surface environmental conditions (on time-scales of ­š105-108 years?) possibly in association with high obliquity-induced climate change (6, 7) and/or volcanic activity. Acknowledgements: This research was conducted under the auspices of the NASA Haughton-Mars Project (HMP) with support from NASA and the National Geographic Society. References: (1) Malin, M. C. and K. S. Edgett 2000. Science 288, 2330-2335. (2) Mellon, M. T. and R. J. Phillips 2001. J. Geophys. Res. 106, 23165-23179. (3) Costard, F. et al. 2002. Science 295, 110-112. (4) Lee, P. et al. 2001. LPSC. XXXII, Houston, TX, Mar 12-16, 2001. (5) Lee, P, et al. 2002. LPSC XXXIII, Houston, TX, Mar 11-15, 2002. (6) Ward, W. R. (1973) Science 181, 260-262. (7) Touma, J. and J. Wisdom (1993) Science 259, 1294-1296.

  17. Historical gully erosion in central Germany reconstructed by lacustrine sediments

    NASA Astrophysics Data System (ADS)

    Enters, Dirk; Kirchner, Gerald; Poulenard, Jérôme; Lücke, Andreas; Frederichs, Thomas; Daut, Gerhard; Zolitschka, Bernd

    2010-05-01

    The formation of lacustrine sediments is controlled by geology, climate, geomorphology and vegetation as well as by human impact. Paleolimnological studies thus provide valuable information about the natural variability of background conditions, for example of climate or nutrient conditions prior to human influence. In addition, various types of human impact on lake systems are identified in lacustrine sediment records. Land-use change has been recognized as one of the most important anthropogenic impacts on lake systems, with soil erosion being a direct consequence of anthropogenic forest clearance and related land-use activities. Soil erosion is by no means solely a consequence of modern agriculture, but has been acting as the dominating shaping factor of the present-day cultural landscapes in Central Europe. Methods to identify periods of enhanced soil erosion include the analysis of soils, colluvial deposits, fluvial sediments and erosional features such as gullies. When applicable and if compared with other records, lake sediments generally provide the most detailed information based on the continuity of the sediment record, and on the high temporal resolution. In addition, lacustrine sediments contain several types of environmental indicators, making it possible to gain supplemental information from multi-proxy investigations. Here, we discuss the potential of lacustrine sediments from the lake "Bernshäuser Kutte", located in southwestern Thuringia (Germany), to reconstruct historical gully formation. Arable land has been in close vicinity to the lake, thus minimizing cascading effects and intermediate sediment storage as it is typical for larger depositional systems. Furthermore, surficial outflow and thus the loss of suspended sediment is negligible, which maximizes the trap efficiency of the lake basin for eroded soil particles and thereby allows a quantification of gully development with a high temporal resolution. Gullies with a depth of several meters

  18. Quantitive analysis of gully long profiles on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Conway, Susan; Balme, Matthew; Murray, John; Towner, Martin

    2010-05-01

    We investigated the scale, slope and curvature properties of gully long profiles on Earth and Mars to ascertain whether gullies on Mars are formed by alluvial and/or debris flow processes. During this investigation we also compared generic slope profiles on Mars to those with gullies. To perform these analyses we used digital elevation models (DEMs) for Earth, the majority of which were derived from ~ 1 m resolution LiDAR data from the UK's NERC ARSF and the USA's NSF NCALM. For Mars we used a technique developed by Kreslavsky [1] to extract elevation data from pairs of RDR HiRISE images. We successfully validated this technique by comparing its results to those from HiRISE DEMs made using automated stereo photogrammetry techniques [2]. We found that gullies produced by debris flow have properties distinct from those formed by alluvial processes on Earth. In general, debris flow gullies are less concave than alluvial gullies, have a basal concavity and have higher slopes than alluvial gullies. We then compared our results from Earth to the gully profiles on Mars and found that properties of gullies on Mars overlap those of both debris flow and alluvial gullies on Earth, however, gullies on Mars are slightly more similar to terrestrial debris flow gullies. In addition gully long profiles on Mars are distinct from generic slope profiles on Mars with some overlap - this shows that the gully forming process has a marked morphological impact on martian slopes. Our observed latitudinal patterns in gully formation are in agreement with previous investigations [3, 4], with greater numbers of gullies found at ~40° and ~70° latitude north and south. In addition we found that gullies at mid-latitudes are more densely packed and occur across whole slope sections (rather than isolated patches), suggesting this region has preferential conditions for gully formation. Our morphological comparison with gullies on Earth suggests that the formation process shifts from pure water

  19. Gullies on Mars: Origin by Snow and Ice Melting and Potential for Life Based on Possible Analogs from Devon Island, High Arctic

    NASA Technical Reports Server (NTRS)

    Lee, Pascal; Cockell, Charles S.; McKay, Christopher P.

    2004-01-01

    Gullies on Devon Island, High Arctic, which form by melting of transient surface ice and snow covers and offer morphologic and contextual analogs for gullies reported on Mars are reported to display enhancements in biological activity in contrast to surrounding polar desert terrain.

  20. Production of activated carbon from coconut shell char in a fluidized bed reactor

    SciTech Connect

    Sai, P.M.S.; Ahmed, J.; Krishnaiah, K.

    1997-09-01

    Activated carbon is produced from coconut shell char using steam or carbon dioxide as the reacting gas in a 100 mm diameter fluidized bed reactor. The effect of process parameters such as reaction time, fluidizing velocity, particle size, static bed height, temperature of activation, fluidizing medium, and solid raw material on activation is studied. The product is characterized by determination of iodine number and BET surface area. The product obtained in the fluidized bed reactor is much superior in quality to the activated carbons produced by conventional processes. Based on the experimental observations, the optimum values of process parameters are identified.

  1. Plasma vasopressin and renin activity in women exposed to bed rest and +G/z/ acceleration

    NASA Technical Reports Server (NTRS)

    Keil, L. C.; Ellis, S.

    1976-01-01

    To study the effect of prolonged recumbency on plasma vasopressin and renin activity, eight women were subjected to 17 days of absolute bed rest. The tolerance to +3G vertical acceleration of the subjects was tested before and after 14 days of bed rest. From day 2 and through day 17 of bed rest, plasma arginine vasopressin (AVP) levels were reduced 33%. Plasma renin activity (PRA) increased 91% above ambulatory control values from days 10 through 15 of bed rest. When compared to precentrifuge values, exposure to vertical acceleration prior to bed rest provoked a 20-fold rise in mean plasma AVP but resulted in only a slight increase in PRA. After bed rest, acceleration increased plasma AVP 7-fold; however, the magnitude of this increase was less than the post +3G acceleration value obtained prior to bed rest. After bed rest, no significant rise was noted in PRA following +3G acceleration. This study demonstrates that prolonged bed rest leads to a significant rise in the PRA of female subjects, while exposure to positive vertical acceleration provokes a marked rise in plasma AVP.

  2. Gully Development in North Ethiopia's Mountains

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Nyssen, Jan; Poesen, Jean; de Mûelenaere, Stephanie; Meire, Ellen; de Dapper, Morgan; Deckers, Jozef; Haile, Mitiku

    2010-05-01

    Understanding trends in gully erosion, and the relation with changes in its triggers, is important to make sustainable development possible in semi-arid regions suffering from low food security and threatened by climatic deterioration. The reconstruction of long-term (1868-2009) patterns in gully erosion in North Ethiopia and environmental control, i.e. LUC changes and rainfall pattern changes, requires an extensive database of ground-based photographs (1868-1975), aerial photographs (1964-1992), satellite images (1972-2009), meteorological station data (1950s-2009) and field measurements. Quantifying gully erosion networks and volumes is done from an integrated analysis of historical ground-based photographs, aerial photographs and IKONOS imagery. Therefore, new methodologies are being developed based on fieldwork, digital photogrammetry and Geographic Information Science techniques. LUC mapping and change analysis for periods prior to satellite imagery and aerial photography is done by developing a new methodology that georeferences LUC boundaries identified on historical photographs to the horizontal plane of the map. For the LANDSAT LUC analysis (1972-2000), images dated 1974-5 were calibrated using photographs of the same period. Therefore, a methodology was developed that involves the development of spectral signatures based on LUC observed on the photographs, and the recording of the location of those LUC units by GPS. Rainfall pattern changes will be analyzed from Rainfall Estimates(2001-2009) and meteorological station data. Early results show that gully erosion was already extensive in the late 19th century, caused by a largely degraded environment and that critical gully expansion occurred after the mid 20th century. Little care was given to land management in 1868 resulting in very low vegetation cover which depleted to a minimum in dry spells like in the 1980s. In recent decades land management practices result in an environmental recovery and

  3. Degradation of the Mitchell River fluvial megafan by alluvial gully erosion increased by post-European land use change, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Shellberg, J. G.; Spencer, J.; Brooks, A. P.; Pietsch, T. J.

    2016-08-01

    Along low gradient rivers in northern Australia, there is widespread gully erosion into unconfined alluvial deposits of active and inactive floodplains. On the Mitchell River fluvial megafan in northern Queensland, river incision and fan-head trenching into Pleistocene and Holocene megafan units with sodic soils created the potential energy for a secondary cycle of erosion. In this study, rates of alluvial gully erosion into incipiently-unstable channel banks and/or pre-existing floodplain features were quantified to assess the influence of land use change following European settlement. Alluvial gully scarp retreat rates were quantified at 18 sites across the megafan using recent GPS surveys and historic air photos, demonstrating rapid increases in gully area of 1.2 to 10 times their 1949 values. Extrapolation of gully area growth trends backward in time suggested that the current widespread phase of gullying initiated between 1880 and 1950, which is post-European settlement. This is supported by young optically stimulated luminescence (OSL) dates of gully inset-floodplain deposits, LiDAR terrain analysis, historic explorer accounts of earlier gully types, and archival records of cattle numbers and land management. It is deduced that intense cattle grazing and associated disturbance concentrated in the riparian zones during the dry season promoted gully erosion in the wet season along steep banks, adjacent floodplain hollows and precursor gullies. This is a result of reduced native grass cover, increased physical disturbance of soils, and the concentration of water runoff along cattle tracks, in addition to fire regime modifications, episodic drought, and the establishment of exotic weed and grass species. Geomorphic processes operating over geologic time across the fluvial megafan predisposed the landscape to being pushed by land used change across an intrinsically close geomorphic threshold towards instability. The evolution of these alluvial gullies is discussed

  4. Effectiveness of powered hospital bed movers for reducing physiological strain and back muscle activation.

    PubMed

    Daniell, Nathan; Merrett, Simon; Paul, Gunther

    2014-07-01

    Battery powered bed movers are becoming increasingly common within the hospital setting. The use of powered bed movers is believed to result in reduced physical efforts required by health care workers, which may be associated with a decreased risk of occupation related injuries. However, little work has been conducted assessing how powered bed movers impact on levels of physiological strain and muscle activation for the user. The muscular efforts associated with moving hospital beds using three different methods; powered StaminaLift Bed Mover (PBM1), powered Gzunda Bed Mover (PBM2) and manual pushing were measured on six male subjects. Fourteen muscles were assessed moving a weighted hospital bed along a standardized route in an Australian hospital environment. Trunk inclination and upper spine acceleration were also quantified. Powered bed movers exhibited significantly lower muscle activation levels than manual pushing for the majority of muscles. When using the PBM1, users adopted a more upright posture which was maintained while performing different tasks (e.g. turning a corner, entering a lift), while trunk inclination varied considerably for manual pushing and the PBM2. The reduction in lower back muscular activation levels may result in lower incidence of lower back injury.

  5. The Role of Morphotectonics in Gully Formation: Two Case Studies in Semiarid Areas

    NASA Astrophysics Data System (ADS)

    Quénéhervé, Geraldine; Maerker, Michael; Zakerinejad, Reza

    2016-04-01

    Tectonic activities significantly contribute to the formation of the existing drainage systems and hence, to landscape evolution. In this study we assessed the influence of morphotectonics in two semiarid catchments in the Zagros range in Southwestern Iran and in the Makuyuni/ Lake Manyara area in Northern Tanzania. Soil erosion and severe gullying affect large parts of both study catchments. Earthquake activities and associated uplifting, fracturing and faulting are still active in large parts of the Zagros range. Tectonic processes in the East African Rift System have significantly contributed to the formation of the current drainage systems and landforms. This study focuses on the morphotectonics with an analysis of topography, drainage networks, stream longitudinal profiles and lineaments. A specific objective is to study the effects of morphotectonic processes and their effects on gullying. The TecDEM software identifies knickpoints showing abrupt changes in the river profiles, hence indicates tectonic activity in turn changing the drainage network. An investigation of base level and statistical moments of the hypsometric curves provides evidences for the spatial distribution of gully erosion phenomena. The knickpoints act as local erosion base level, and any changes in the knickpoint location leads to a response of erosional processes in the watershed above the knickpoints. Hence gully systems might indicate morphotectonic activities as one of the triggering factors in gully formation. The results of regional tectonic instability suggest that tectonic processes are a significant factor for the current landscape evolution in the two basins. We illustrate that severe gully erosion is strongly related to these tectonic processes, especially in the Southwest of the Mazayjan catchment (Iran) and in the Northeastern and Northern part of the Makuyuni catchment (Tanzania).

  6. Present-day formation and seasonal evolution of linear dune gullies on Mars

    NASA Astrophysics Data System (ADS)

    Pasquon, Kelly; Gargani, Julien; Massé, Marion; Conway, Susan

    2016-04-01

    Linear dune gullies are an enigmatic sub-type of martian gullies. As their name suggests they only occur on sandy substrates and comprise very long (compared to their width) straight or sinuous channels, with relatively small source areas and almost inexistent deposits. This specific morphology has never been observed on terrestrial dunes and its formation process on Mars is still unclear [e.g. 1, 2, 3]. Here, we present the results of the first systematic survey for these features in Mars' southern hemisphere and an in-depth study of six dune fields where repeat-imaging allows us to monitor the changes over time of these linear gullies. This study was performed with HiRISE images at 25-30 cm/pix and 1 m/pix elevation data derived from HiRISE stereo images. We find the latitudinal distribution and orientation of linear gullies is broadly consistent with the general population of martian gullies. They occur predominantly between 36.3°S and 54.3°S, and occasionally between 64.6°S and 70.4°S. They are oriented towards SSW (between 150°N and 260°N). In contrast with the general gully population, however, we find that these gullies are extremely active over the 5 Mars years of images. Activity comprises: (i) appearance of new channels, (ii) elongation of existing channels, (iii) complete or partial reactivation, and (iv) disappearance of gullies. Gully channels can elongate by an average ~100 m per year. Their intense activity and the progressive disappearance of linear gullies argues against the hypothesis that these are remnant morphologies left over from previous periods of high obliquity millions of years ago. The activity of linear dune gullies reoccurs every year between the end of winter and the beginning of spring (Ls 167.4° - 216.6°), coinciding with the final stages of the sublimation of annual CO₂ frosts. This activity often coincides spatially and temporally with the appearance of Recurrent Diffusing Flows (RDF) - dark patches which surround the

  7. Evolution of continental slope gullies on the northern california margin

    USGS Publications Warehouse

    Spinelli, G.A.; Field, M.E.

    2001-01-01

    A series of subparallel, downslope-trending gullies on the northern California continental slope is revealed on high-resolution seismic reflection profiles imaging the uppermost 50 m of sediment. The gullies are typically 100 m wide and have 1 to 3 m of relief. They extend for 10 to 15 km down the slope and merge into larger channels that feed the Trinity Canyon. In the lower half of the 50 m stratigraphic section, the gullies increase in both relief and number up section, to maxima at a surface 5 to 10 m below the last glacial maximum lowstand surface. Gully relief increased as interfluves aggraded more rapidly than thalwegs. Erosion is not evident in the gully bottoms, therefore gully growth was probably due to reduced sediment deposition within the gullies relative to that on interfluves. As the gullies increased in relief, their heads extended upslope toward the shelfbreak. At all times, a minimum of 10 km of non-gullied upper slope and shelf stretched between the heads of the gullies and the paleo-shoreline; the gullies did not connect with a subaerial drainage network at any time. Gully growth occurred when the gully heads were in relatively shallow water (??? 200 m paleo-water depth) and were closest to potential sediment sources. We suggest that prior to the last glacial maximum, the Mad River, then within 10 km of the gully heads, supplied sediment to the upper slope, which fed downslope-eroding sediment flows. These flows removed sediment from nearly parallel gullies at a rate slightly slower than sediment accumulation from the Eel River, 40 km to the south. The process or processes responsible for gully growth and maintenance prior to the last glacial maximum effectively ceased following the lowstand, when sea level rose and gully heads lay in deeper water (??? 300 m water depth), farther from potential sediment sources. During sea-level highstand, the Mad River is separated from the gully heads by a shelf 30 km wide and no longer feeds sediment flows

  8. A classification of martian gullies from HiRISE imagery

    NASA Astrophysics Data System (ADS)

    Auld, Katherine S.; Dixon, John C.

    2016-10-01

    Due to the large and varied population of gullies observed in Mars High Resolution Imaging Science Experiment (HiRISE) imagery that exhibit diverse characteristics, this paper develops a classification of martian gullies based on their morphological characteristics. This provides a firmer foundation for future investigation of the genesis of different gully morphologies. The Mars Reconnaissance Orbiter (MRO) image catalog on the HiRISE website was examined and 869 images, chosen from the first 25,000 orbits, show a wide variety of gully morphologies. The images were analyzed using ENVI 4.4 and ENVI Zoom and the gullies were cataloged and divided into groups based on the presence and character of the dominant morphological components of alcove, channel, and apron associated with each gully. 7519 gullies were identified in the images and the length and width of the components were measured in ENVI to facilitate classification. Seven classes were developed based on morphology.

  9. Drama Hike: Land of the Hully Gullies

    ERIC Educational Resources Information Center

    Jordison, Jerry

    2007-01-01

    Designed for primary and junior students, the Drama Hike is a real walk into the woods: smelling, feeling and seeing Nature. It is also an imaginative search for ancient civilizations, in this case the "Hully Gullies." The purpose of the trip is to discover what these people might have looked like, their social habits, religion, sports and so on.…

  10. Tools for Ephemeral Gully Erosion Process Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Techniques to quantify ephemeral gully erosion have been identified by USDA Natural Resources Conservation Service (NRCS) as one of gaps in current erosion assessment tools. One reason that may have contributed to this technology gap is the difficulty to quantify changes in channel geometry to asses...

  11. Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

    USGS Publications Warehouse

    Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua

    2015-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

  12. Recent climate cycles on Mars: Stratigraphic relationships between multiple generations of gullies and the latitude dependent mantle

    NASA Astrophysics Data System (ADS)

    Dickson, James L.; Head, James W.; Goudge, Timothy A.; Barbieri, Lindsay

    2015-05-01

    Reconstructions of the orbital parameters of Mars spanning the last ∼20 Myr, combined with global circulation models, predict multiple cycles of accumulation and degradation of an ice-rich mantle in the mid-latitudes, driven primarily by insolation at the poles during periods when obliquity was more than ten degrees greater than it is today (i.e., >∼35°). While evidence of an ice-rich "latitude dependent mantle" (LDM) consistent with these predictions is abundant, features indicative of cycles of emplacement and degradation of this unit are isolated and rare. In addition, fundamental physical properties of the LDM, such as paleo-thickness maxima, have not been determined. Gullies, which are sinuous channels found on steep slopes in mid- and high-latitudes, interact with the LDM and provide a stratigraphic feature useful for documenting both cyclical emplacement/removal and thickness estimates in past climate regimes. In the southern hemisphere, where gullies are most common, we present extensive evidence of (1) cyclical degradation and removal of gullies in the lower mid-latitudes (30-40°S), and (2) burial and exhumation of inverted gully channels in the transitional latitude band between dissected and preserved LDM (40-50°S), which can only be accounted for if an additional tens of meters of LDM were present at these locations during channel formation. These relationships support a model in which end-to-end gully evolution is controlled by the behavior of the LDM: at lower latitudes, gullies incise an ice-rich substrate and are removed when that ice becomes unstable, and at higher latitudes gullies are buried by successive emplacement of LDM where ice remains stable near the surface. Further, the presence of dormant buried gullies implies that present-day activity within gullies, likely to be controlled by the behavior of CO2 frost, is insufficient to explain the entire gully population, and that conditions conducive to increased gully activity preceded the

  13. Plasma lactic dehydrogenase activities in men during bed rest with exercise training

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Juhos, L. T.; Young, H. L.

    1985-01-01

    Peak oxygen uptake and the activity of lactic dehydrogenase (LDH-T) and its five isoenzymes were measured by spectrophotometer in seven men before, during, and after bed rest and exercise training. Exercise training consisted of isometric leg exercises of 250 kcal/hr for a period of one hour per day. It is found that LDH-T was reduced by 0.05 percent in all three regimens by day 10 of bed rest, and that the decrease occurred at different rates. The earliest reduction in LDH-T activity in the no-exercise regimen was associated with a decrease in peak oxygen uptake of 12.3 percent. It is concluded that isometric (aerobic) muscular strength training appear to maintain skeletal muscle integrity better during bed rest than isotonic exercise training. Reduced hydrostatic pressure during bed rest, however, ultimately counteracts the effects of both moderate isometric and isotonic exercise training, and may result in decreased LDH-T activity.

  14. Adsorption of organics from tar sand water by activated carbon in packed beds. Final report

    SciTech Connect

    Hines, A.L.; Pedram, E.O.

    1982-12-30

    The adsorption of TS-1S and TS-2C tar sand waters were studied at 278 and 298/sup 0/K on activated carbon in both batch and packed bed experiments. The isotherms were nonlinear over the entire liquid concentration ranges. Breakthrough curves were obtained in packed bed experiments as a function of bed lengths, particle size, and liquid velocity. A mechanistic approach was used to solve the mass transfer equations for the packed adsorber, the mass transfer coefficients and the rates of adsorption were calculated. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.

  15. Conditions of gully development within piedmont areas with examples from the western part of the Getic Piedmont, Romania.

    PubMed

    Boengiu, Sandu; Vladut, Alina; Marinescu, Emil

    2012-04-01

    Features of gully morphometry and associated relief characteristics emphasize that gully develop under a wide variety of rock conditions, rainfall regimes, geomorphic predisposition, and human influence. Consequently, many slopes within piedmont areas, in this case, the Getic Piedmont, are characterized by dense gully systems, as there occur excessive clearing, inappropriate land use, compaction of the soil caused by grazing, on the general background of a favourable climate. Both rainfall and runoff factors must be considered in assessing a water erosion problem. The erosional slope development within the Getic Piedmont was evaluated based on maps and field studies in the last 15 years, which emphasized that about 20% of the total surface of the piedmont is affected by gully erosion. The results show that the factors leading to the strong gully erosion in this area include - the widely distributed friable rocks, the unique geomorphologic configuration, the strong and time-concentrated rainfall, the alternance of drought-humid periods that prepares the ground for the development of fissures in soils, the drought that influence the growth and recovery of vegetation, and the intense human activities. Gully erosion is one of the most visible forms of soil erosion, which affects its productivity, provides considerable material transport- torrential transports, debris flow, restricts land use, and threatens local communities.

  16. Investigating the Martian Gullies for Possible Brine Origin: A Preliminary Search for Evaporite Minerals Using THEMIS Data

    NASA Technical Reports Server (NTRS)

    Lane, M. D.; Christensen, P. R.

    2003-01-01

    Photographs taken by both the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor (MGS) spacecraft and the Thermal Emission Imaging System (THEMIS) aboard the Mars Odyssey (MO) spacecraft have shown the presence of young gullies on Mars. These gullies occur at middle and high latitudes (predominantly in the southern hemisphere) in the walls of both impact craters and canyons. They are thought possibly to be formed by the melting of ground ice, groundwater seepage (possibly as brines), surface runoff, or even liquid CO2, activated sporadically as a result of oscillations in Mars orbit. For this work, the hypothesis of gully formation being related to the outflow of brines will be investigated through the observation and study of spacecraft data. Brine rich fluids expunged from underground onto the walls of canyons and craters would either evaporate or freeze and sublimate. Removal of water from a brine by evaporation or sublimation would cause the solutes to precipitate as evaporite minerals on the canyon and crater walls or at the base of the walls, and possibly on the canyon and crater floors. Hence, the gully sites are ideal target areas to search for evaporites using THEMIS data. The objective of this work is to survey the recently acquired THEMIS data for spectral evidence of evaporite minerals, with a focus on areas of gully formation. Identifying salt mineral residues could provide chemical evidence in support of the brine origin of the Martian gullies.

  17. Rainfall Threshold For Ephemeral Gully Erosion In Foothill Cultivated Lands (Wiśnicz Foothills, Poland)

    NASA Astrophysics Data System (ADS)

    Święchowicz, Jolanta

    2016-04-01

    The paper presents the results of ephemeral gullies studies carried out in hydrological years 1998-2009 on the Jagiellonian University's farm, which is located in the village of Łazy (Southern Poland). The farm covers an area of 103 ha. The dominant relief type is low hills. Soil erosion hardly ever occurs on the whole area of slopes in the catchment, and transport of eroded material is irregular and not simultaneous. The formation of ephemeral gullies happens once a year or once in a few years. The events are occasional and happen locally. Ephemeral gullies most frequently form and develop on cultivated slopes in natural drainage lines or they are associated with man-made agricultural activities like field borders, furrows, tractor traces and cart roads. The research carried out in Wiśnicz Foothills shows that the development of ephemeral gullies was limited both by extrinsic (erosivity of rain) and intrinsic thresholds (the length of slope, the presence (or lack of) Bt horizon, soil moisture, type and calendar of crops and farming activities). Ephemeral gullies usually form and develop during single rain or several subsequent rains of high erosivity (of several hundred MJmmha-1h-1) on long cultivated slopes, particularly at the beginning of vegetation period, when most slopes are devoid of vegetation cover or plants are in the initial stage of growth. The process of enlarging and deepening of ephemeral gullies slows down when the incision of a gully reaches Bt horizon. Then the effectiveness of even high erosivity rainfall is much smaller. Similarly, very high erosivity of rainfall in the middle of the vegetation season is not able to cause such serious effect and the intensity of deepening of ephemeral gullies is much smaller. The process of intensified linear water erosion is more significant on commercial farms with a large acreage of crops. As a result all the mapped erosion forms were disposed of by farmers (e.g. by ploughing or filling up). If these forms

  18. Experiences of a gully survey in the Gödöllő Hillside Landscape Protection District, Hungary

    NASA Astrophysics Data System (ADS)

    Szabó, Boglárka; Bolf, Balázs; Szabó, Judit; Centeri, Csaba

    2016-04-01

    size of the catchment of the investigated gully was measured as 214,873 square meters. We estimated the amount of the runoff arriving into the surveyed gully for 14 months, the result of the measure was 22,741.6 cubic meter per month. In case of 4 dams the retention effect was examined. The four protection measures hold up nearly 160 tons of sediment in the gully bed.

  19. Systematic reviews of bed rest and advice to stay active for acute low back pain.

    PubMed Central

    Waddell, G; Feder, G; Lewis, M

    1997-01-01

    BACKGROUND: In the United Kingdom (UK), 9% of adults consult their doctor annually with back pain. The treatment recommendations are based on orthopaedic teaching, but the current management is causing increasing dissatisfaction. Many general practitioners (GPs) are confused about what constitutes effective advice. AIM: To review all randomized controlled trials of bed rest and of medical advice to stay active for acute back pain. METHOD: A systematic review based on a search of MEDLINE and EMBASE from 1966 to April 1996 with complete citation tracking for randomized controlled trials of bed rest or medical advice to stay active and continue ordinary daily activities. The inclusion criteria were: primary care setting, patients with low back pain of up to 3 months duration, and patient-centred outcomes (rate of recovery from the acute attack, relief of pain, restoration of function, satisfaction with treatment, days off work and return to work, development of chronic pain and disability, recurrent attacks, and further health care use). RESULTS: Ten trials of bed rest and eight trials of advice to stay active were identified. Consistent findings showed that bed rest is not an effective treatment for acute low back pain but may delay recovery. Advice to stay active and to continue ordinary activities results in a faster return to work, less chronic disability, and fewer recurrent problems. CONCLUSION: A simple but fundamental change from the traditional prescription of bed rest to positive advice about staying active could improve clinical outcomes and reduce the personal and social impact of back pain. PMID:9474831

  20. Using SHARAD radar soundings to evaluate the origin of martian gullies and pingos

    NASA Astrophysics Data System (ADS)

    Nunes, D. C.; Smrekar, S. E.; Safaeinili, A.; Phillips, R. J.; Seu, R.

    2008-12-01

    Gullies are some of the geologically youngest features on Mars (< 10 Myr), and their morphology, defined normally by alcove-channel-aprons, led instantly to the hypothesis of formation by the action of fluid water. Hence, gullies might offer an opportunity to constrain the recent history of water on the planet. Different models propose a variety of mechanisms to produce the liquid, with sources generally falling into either surficial (mantling) deposits or ground water/ice. The SHARAD sounding radar aboard the Mars Reconnaissance Orbiter, with a ~10 m subsurface vertical resolution, may have a strong role to play in testing the water hypothesis for the origin of gullies and in characterizing the source of the fluid. We have surveyed radar data for nearly 50 gullies, which occur predominantly at mid-latitudes on both hemispheres of Mars. In most of these cases, strong subsurface reflectors are not observed. In the few cases where strong subsurface reflections are observed, they possibly relate to volcanic units (e.g. Amazonis and Arcadia Planitiae). Weak, near-surface (< 200 m) reflectors appear to be present at some but not all gullies. We are also examining another type of feature postulated to arise from subsurface water/ice activity: pingos. These are nearly circular mounds hundreds of meters across and tens of meters high that are characterized by fractures or collapsed pits on their crests. On Earth, pressurization at depth leads to injection and subsequent freezing of water into the shallow subsurface. The uplifted layer of permafrost cracks as the mound grows and collapse pits form over time due to ice loss. As in the case of gullies, weak shallow subsurface reflections are present in some of the pingo occurrences. Up to this point, however, our limited survey of gullies and pingos is not supportive of shallow aquifers, as the high dielectric constant of liquid water would produce strong reflections, according to simple propagation models. The weak

  1. Controlling Gully Erosion: An Analysis of Land Reclamation Processes and Challenges in Chambal Badlands, India

    NASA Astrophysics Data System (ADS)

    Pani, Padmini

    2016-04-01

    Gully erosion is among the significant environmental problems in the Central Indian states. The Chambal badlands, spread over an area of around 4000 sq. kms is among the worst affected regions in terms of land degradation. The enormity of the Chambal ravines, which achieve depths of more than 60 metres, points to the significance of the geological explanation, suggesting that neotectonics may have paved the way for ravine erosion, but it is most definitely exacerbated by anthropogenic activities. Although, there is field evidence that ephemeral gully erosion is responsible for significant soil losses, little is known about the contributing factors. The region also faces significant developmental challenges and the inaccessibility and low productivity of the area contributes to its continued underdevelopment. This study uses a combination of geo-spatial techniques and physical and socio-economic field survey to evaluate the responses to gully erosion and its implications. This paper attempts to study (a) extent and severity of gully erosion process in the Chambal badlands; (b) an evaluation of reclamation measures undertaken by various agencies, including the affected people; (c) to examine the sustainability implications of land reclamation measures. The extent, pattern and inter-temporal changes of gully erosion have been examined through various mapping techniques and field survey. The land reclamation have been mapped using satellite images and ground truth verification. The various kinds of land reclamation measures that have been undertaken on the ground and their sustainability implications have been investigated through survey of affected households in selected villages. The results show that in response to the severe loss of agricultural land because of gully head encroachment in the agricultural field and decline in land productivity, farmers have undertaken various land reclamation measures, including mechanised land levelling. The land levelling

  2. Sharp View of Gullies in Southern Winter

    NASA Technical Reports Server (NTRS)

    2006-01-01

    20 November 2006 Crisp details in a suite of mid-latitude gullies on a crater wall are captured in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) view obtained in southern winter on 12 October 2006. During southern winter, shadows are more pronounced and the atmosphere is typically quite clear. These gullies, which may have formed in relatively recent martian history by erosion caused by flowing, liquid water, are located in a crater on the east rim of Newton Crater near 40.4oS, 155.3oW. Sunlight illuminates the scene from the upper left. The picture covers an area about 3 km (1.9 mi) wide; the crater rim is on the right side of the image, the crater floor is on the left. North is toward the top/upper left.

  3. Constraining the Formation of Submarine Gullies on Continental Slopes

    NASA Astrophysics Data System (ADS)

    Shumaker, L.; Jobe, Z. R.; Graham, S. A.

    2015-12-01

    Submarine gullies are ubiquitous on continental slopes and steep areas of seafloor worldwide, but their role in sediment transport remains unresolved. Direct observation of flows in the submarine realm is rare and expensive, but by analyzing basic geometries of gullies in the sedimentary record, it is possible to gain insight into the behavior of the flows that formed them. In shallow 3D seismic reflection data from the Taranaki Basin, New Zealand, we document gullies preserved in a Pliocene-Pleistocene progradational margin sequence. These gullies commonly form aggradational complexes hundreds of meters thick, showing alternating periods of erosion, inactivity, and roughly self-similar aggradation in response to slope sedimentation. Erosional phases speak of modification by energetic turbidity currents, whereas sediment drapes point to extended periods of flow quiescence and hemipelagic deposition. We pair these observations with morphometrics of over 600 gullies in seafloor bathymetry from continental margins worldwide. The slopes of these modern gullies and interfluves are both well described by a power-law decay with along-profile distance. The decay of slopes with distance (concavity) obtained from power-law relationships for interfluves and gullies are well correlated, although gullies attain higher slopes and are slightly more concave than neighboring interfluves. The self-similar growth of gullies in the subsurface and the strong similarity between gully and interfluve profiles in all datasets suggests a link between the evolution of gullies and of the slopes on which they form. We conclude by presenting a conceptual model in which gully and slope morphology are tightly coupled.

  4. Properties of Spent Active Coke Particles Analysed via Comminution in Spouted Bed

    PubMed Central

    Buczek, Bronislaw

    2013-01-01

    Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals) through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases. PMID:24459454

  5. Morphology and hydrodynamics of wave-cut gullies

    NASA Astrophysics Data System (ADS)

    Priestas, A. M.

    2010-12-01

    Wave-cut gullies are triangular incisions formed by the concentration of wave energy on a vegetated marsh scarp. Wave gullies are usually equispaced and incise the marsh and enlarge in time both in length and width. Here we provide a high resolution survey of ten wave gullies formed along the chenier plain of the Rockefeller Wildlife Refuge, Louisiana, USA. Our measurements capture the morphologic character, evolution, and erosion rates of wave-cut gullies over a two month period. We further relate changes in morphology to geometric factors and shoreline retreat. Finally, we present the first analysis of wave data measured by acoustic doppler velocity profilers to show how propagating waves are transformed inside a wave-cut gully in order to describe the processes leading to their formation. Results show that waves of intermediate period (4-6 sec) yield very strong swash currents that hit the gully head detaching marsh substrate and triggering headward erosion. A conceptual model of wave gully evolution is finally presented as an explanation for this non-uniform, episodic shoreline erosion. Snapshots of a wave propagating in wave gully. The convergent geometry of wave gullies concentrates wave energy and incites rapid headward erosion.

  6. FLUIDIZED BED STEAM REFORMING FOR TREATMENT AND IMMOBILIZATION OF LOW-ACTIVITY WASTE

    SciTech Connect

    HEWITT WM

    2011-04-08

    This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of fluidized bed steam reforming and its possible application to treat and immobilize Hanford low-activity waste.

  7. Identification and active disturbance rejection for the JPL Phase B Test Bed

    NASA Astrophysics Data System (ADS)

    Eldred, Daniel B.; Gibson, J. S.; Li, Wu-Jeng

    1993-09-01

    Active disturbance rejection to minimize optical path length error is illustrated by experimental results from the JPL Phase B Test Bed, which incorporates an interferometric sensor and a controllable trolley mounted on a flexible truss structure. The controller actively isolates the optical instruments from structural vibrations induced by external disturbances consisting of linear combinations of sinusoidal signals.

  8. Bed rest suppresses bioassayable growth hormone release in response to muscle activity

    NASA Technical Reports Server (NTRS)

    McCall, G. E.; Goulet, C.; Grindeland, R. E.; Hodgson, J. A.; Bigbee, A. J.; Edgerton, V. R.

    1997-01-01

    Hormonal responses to muscle activity were studied in eight men before (-13 or -12 and -8 or -7 days), during (2 or 3, 8 or 9, and 13 or 14 days) and after (+2 or +3 and +10 or +11 days) 17 days of bed rest. Muscle activity consisted of a series of unilateral isometric plantar flexions, including 4 maximal voluntary contractions (MVCs), 48 contractions at 30% MVC, and 12 contractions at 80% MVC, all performed at a 4:1-s work-to-rest ratio. Blood was collected before and immediately after muscle activity to measure plasma growth hormone by radioimmunoassay (IGH) and by bioassay (BGH) of tibia epiphyseal cartilage growth in hypophysectomized rats. Plasma IGH was unchanged by muscle activity before, during, or after bed rest. Before bed rest, muscle activity increased (P < 0.05) BGH by 66% at -13 or -12 days (2,146 +/- 192 to 3,565 +/- 197 microg/l) and by 92% at -8 or -7 days (2,162 +/- 159 to 4,161 +/- 204 microg/l). After 2 or 3 days of bed rest, there was no response of BGH to the muscle activity, a pattern that persisted through 8 or 9 days of bed rest. However, after 13 or 14 days of bed rest, plasma concentration of BGH was significantly lower after than before muscle activity (2,594 +/- 211 to 2,085 +/- 109 microg/l). After completion of bed rest, muscle activity increased BGH by 31% at 2 or 3 days (1,807 +/- 117 to 2,379 +/- 473 microg/l; P < 0.05), and by 10 or 11 days the BGH response was similar to that before bed rest (1,881 +/- 75 to 4,160 +/- 315 microg/l; P < 0.05). These data demonstrate that the ambulatory state of an individual can have a major impact on the release of BGH, but not IGH, in response to a single bout of muscle activity.

  9. Carbonate slope gully system on the Westside Great Bahama Bank

    NASA Astrophysics Data System (ADS)

    Principaud, Mélanie; Mulder, Thierry; Borgomano, Jean; Ducassou, Emmanuelle; Hanquiez, Vincent; Gillet, Hervé; Marieu, Vincent; Sorriaux, Patrick

    2013-04-01

    Gullies are commonly observed on submarine slopes along many continental margins. They are generally small, straight, shallow channels with a depth that does not exceed a few tens of meters. They form on relatively steep slopes. They are important features for downslope sediment transfer from the outer continental shelf to the continental slope and rise. Data collected during the first leg of the Carambar cruise (Nov. 1st - Nov. 15th, 2010) on the RV "Le Suroît" show that the western slope of the Great Bahamas Bank is characterized by the presence of gullies that extend about 100 km from North to South along the carbonate platform. Gullies appear on the upper slope at approximately 410 m water depth in a carbonated mud-dominated environment. Their initiation follows the presence of sediment waves. They extend over a 3° steeped slope down to 610 m water depth. The gully heads are not connected to the platform and to any significant carbonate depositional system. They are relatively linear, sub-parallel, with a symmetric to asymmetric V-shaped cross section and incision does not exceed 30 m. Average gully length and spacing are 4000 and 800 m respectively. A detailed morphometric study based on EM302 multibeam bathymetry and very-high resolution seismic data (Chirp sub bottom profiler) combined with a statistical analysis allowed the gullied slope to be divided into two distinct areas. (1) The northern area characterized by regularly-spaced gullies (spacing varies from 750 to 800 m from North to South). They are generally linear and sub-parallel with an average length of 4 km. Their depth are usually lower than 10 m. Asymmetry is greater in the central region of gullies (northern flank is steeper than southern flank) and seems to be correlated with an increase in gully depth and a decrease in gully spacing. (2) The southern area is characterized by irregularly-shaped gullies that are usually truncated by a large 40 m high N-S deformation escarpment. Gullies have

  10. 3D laser scanning as a new tool of assessment of erosion rates in forested loess gullies (case study: Kolonia Celejów, Lublin Upland)

    NASA Astrophysics Data System (ADS)

    Kociuba, Waldemar; Janicki, Grzegorz; Rodzik, Jan

    2014-06-01

    The gully network existing in a number of loess areas under agricultural use in the Lublin Upland has been subject to secondary vegetation succession. The dense plant cover makes the application of remote sensing methods difficult. As a result, topographic maps frequently present the general outlines of the gullies, and in the case of a considerable dissection of the badlands type - only the boundaries between the occurring forest assemblages and cultivated fields. Aerial photographs do not permit tracing the modern development of the lateral branches of the gully, or the qualitative assessment of material transported in the gully system. The application of satellite geodesy tools is also problematic due to weak penetration of tree crowns by the signal. The application of traditional geodesic tools, including laser total stations, is time-consuming and strenuous, particularly in the case of measurement of microforms. Moreover, measurements by means of total stations require relevant preparation of the polygon, and frequently the removal of bushes and high perennials. Such measurement problems can be solved by the application of the modern Terrestrial Laser Scanning (TLS) technology. The primary objective of the paper is to develop a strategy of measurement of active gully landforms, and the application of the TLS technology for geomorphological mapping in forested and branched gully systems. Moreover, detailed measurements of the geometry of the secondary landforms permit the monitoring of tendencies and the determination of the rate of development of gullies

  11. Fluvial Discharge Rates of Martian Gullies: Slope Measurements From Stereo HiRISE Images and Numerical Modeling of Sediment Transport

    NASA Astrophysics Data System (ADS)

    Parsons, R. A.; Nimmo, F.; Kreslavsky, M.

    2008-12-01

    Using a stereo pair of HiRISE images of a crater slope incised by fourteen gullies at -37.86 N, 217.92 E we calculate relative elevation changes between pairs of hand-selected points. Using the method of Kreslavsky [1]. The background slope on which the gullies are located has a slope of 22 degrees. Out of the five gullies we analyzed, all show a steadily decreasing slope from an average of 30 ± 4 degrees at the alcove to 16 ± 2 degrees at the apron. These measurements are in agreement with previous gully slope measurements done at MOLA resolution in a different region [2]. The slope beyond the base of the gully aprons is 4±1 degrees. The depth of alcove incision in nine of the gullies is 17±8.5~m. We take advantage of this slope and incision data to determine the evolution of a one-dimensional gully profile over time with a 1D sediment transport model [3]. The shear stress applied to the channel bed by flowing water is τ = ρ g h sinθ where h is the channel depth, g is gravity, and h is the channel depth. The rate of transport is non-linearly related to τ/τrg where the reference stress for a gravel bed is τrg = 0.035 ( (s-1)ρ g Dg ) where s is the ratio of sediment to water density, ρ is 1000~m3, and Dg is the sediment grainsize. The two significant unknowns in applying the theory to Martian gullies are the sediment grainsize and channel depth. We ran simulations for various channel depths and grainsizes to get a range of water discharges and simulation times that result in alcoves 25~m deep. Erosion is rapid due to the high slopes; incision rates decrease with decreasing channel depth and increasing grainsize. For grains 20~cm in diameter and a conservatively low channel depth of 20~cm, alcove incision occurs over a 5~h period, discharging a volume of 8500 m3 of water. These discharges assume a 1~m wide channel and a constant, bank-full discharge over the duration of the simulation. Gullies are spaced about every 500~m along the slope. If liquid water

  12. Geomorphological descriptions of seasonal processes on Mars: Linear Gullies and Recurrent Diffusing Flows on the intra-crater dunes fields

    NASA Astrophysics Data System (ADS)

    Pasquon, K.; Gargani, J.; Massé, M.

    2015-10-01

    Linear Gullies are seasonal processes located on the intra-crater dunes fields. They are mainly located between 43°40'S and 52°2'S on dunes with a slight slope (˜13°) facing SSW (mainly between 150°N and 260°N). The progression of Linear Gullies happens every years between the end of winter and the beginning of spring (between Ls 167.4° and Ls 216.6°), when the CO finally defrosts on the dunes fields. Each year, a Recurrent Diffusing Flow spreads on Linear Gullies area from the end of winter (Ls 167.4°) to the beginning of autumn (Ls 21.9°), with a maximum activity between Ls 167.4° and Ls 192.3°. This flow takes an active part in the Linear Gullies creation/upkeep and could participate to the pits development. We highlight an albedo decrease of 42% during the pits activity. This important and very transient decreasing could be hardly explained by a dry movement only. We thus suggest that the Recurrent Diffusing Flows could be linked to the presence of a fluid or a liquid spreading in the shallow sub-surface. A link between CO cycle and the Linear Gullies could be consistent with their development timing. Brines participation can't be excluded.

  13. Gully catchment as sediment sinks, not just a source

    NASA Astrophysics Data System (ADS)

    Larsen, Annegret; Heckmann, Tobias; Larsen, Joshua; Bork, Hans-Rudolf

    2016-04-01

    Catchment wide sediment fluxes have been modified throughout the Anthropocene, but it`s spatial and temporal dimension is still under debate. Here, we present a long-term sediment budget, highlighting the overlooked role of gullies as significant sediment sinks, and challenging the prevalent view of gullies as being exclusively conveyor belts of sediment. This is important, as sediment delivery from hillslopes to trunk streams represents a significant pathway of mass transfer in the landscape, with a large fraction facilitated by gully systems. In this study, we analysed the sediment mass balance and storage dynamics within a headwater gully catchment in central Europe over the last ~12 500 yrs. Human induced erosion resulted in hillslope erosion rates ~2.3 times higher than under naturally de-vegetated conditions during the Younger Dryas. However the total sediment inputs to the gully system (and therefore gully aggradation), were similar. Net gully storage has consistently increased to become the second largest term in the sediment budget after hillslope erosion (storage is ~45% and ~73% of inputs during two separate erosion and aggradation cycles). In terms of the depletion of gully sediment storage, the sediment mass balance shows that export beyond the gully fan was not significant until the last ~500 years, due to reduced gully fan accommodation space. The significance of storage effects on the gully sediment mass balance, particularly the export terms, means that it would be difficult to determine the influences of human impact and / or climatic changes from floodplain or lake sedimentary archives alone and that the sediment budgets of the headwater catchments from which they drain are more likely to provide these mechanistic links.

  14. Visualization of the exothermal VOC adsorption in a fixed-bed activated carbon adsorber.

    PubMed

    Le Cloirec, P; Pré, P; Delage, F; Giraudet, S

    2012-01-01

    Activated carbon fixed beds are classically used to remove volatile organic compounds (VOCs) present in gaseous emissions. In such use, an increase of local temperature due to exothermal adsorption has been reported; some accidental fires in the carbon bed due to the removal of high concentrations of ketones have been published. In this work, removal of VOCs was performed in a laboratory-scale pilot unit. In order to visualize the increase in local temperature, the adsorption front was tracked with a flame ionization detector and the thermal wave was simultaneously visualized with an infrared camera. In extreme conditions, fire in the adsorber and the combustion of activated carbon was achieved during ketone adsorption. Data have been extracted from these experiments, including local temperature, front velocity and carbon bed combustion conditions.

  15. AnnAGNPS Ephemeral Gully Erosion Simulation Technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheet and rill erosion conservation management technologies, such as the Revised Universal Soil Loss Equation (RUSLE), have provided valuable tools in reducing cropland erosion, but have not considered the impact of ephemeral gully erosion. Tillage-induced ephemeral gully erosion has been shown to ...

  16. Investigating gully flow emplacement mechanisms using apex slopes

    NASA Astrophysics Data System (ADS)

    Kolb, Kelly Jean; McEwen, Alfred S.; Pelletier, Jon D.

    2010-07-01

    The origin of the martian gullies has been much debated since their discovery by the Mars Orbiter Camera (MOC, Malin, M.C., Edgett, K.S. [2000]. Science 288, 2330-2335). Several previous studies have looked at slope gradients in and around gullies, but none have used Digital Elevation Models (DEMs) from the High Resolution Imaging Science Experiment (HiRISE, McEwen, A.S., and 14 colleagues [2007]. J. Geophys. Res. 112 (E05), E0505S02), which has a pixel scale down to 25 cm/pixel. We use five 1 m/post HiRISE DEMs to measure gully apex slopes, the local channel gradient at the upslope extent of the gully debris apron, which marks a shift from erosion to deposition. The apex slope provides information about whether a flow was likely a typical dry granular flow (begins depositing on slopes ˜21°) or fluidized by some extra mechanism (depositing on shallower slopes). We find that 72% of the 75 gully fans studied were likely emplaced by fluidized flows. Relatively old gullies appear more likely to have hosted fluidized flows than relatively fresh gullies. This suggests a time and location dependent fluidizing agent, possibly liquid water produced in a different climate as previously proposed. Our results do not provide evidence for water-rich flows in gullies today.

  17. Cold Desert Fluvial Sedimentation and Buried Ice Geology: Garwood Valley (Antarctica) as a Guide to Martian Delta and Gully Geomorphology, Mineralogy, and Biomarker Distribution

    NASA Astrophysics Data System (ADS)

    Levy, J.; Fountain, A. G.; O'Connor, J. E.

    2011-12-01

    The cold, polar desert environmental conditions of the McMurdo Dry Valleys serve as an analog for the physical processes thought to affect Mars. Garwood Valley, one of the McMurdo Dry Valleys (78°S, 164°E) has a mean annual temperature of ~255 K and experiences <50 mm of water-equivalent snowfall per year (most of which sublimates). During the last glacial maximum, the West Antarctic/Ross Ice Sheet ice filled and blocked the lower end of Garwood Valley. Despite surface temperatures ~12 K lower than at present (243 K average), alpine glacier and ice sheet melt in Garwood Valley was sufficient to form a lake in the resulting closed basin, which partly filled with a thick (>8 m) stack of deltaic and lacustrine sediments. In places, the delta sediments overlie remnants of the valley-filling ice plug. The delta sediments are found in a complex composed of three stepped surfaces that suggest sequential lowering of the lake level via incision through the valley-filling ice plug. The delta stratigraphy has been exposed by erosion, driven by massive ice melt and lateral erosion by the modern Garwood River (an alpine glacier-fed river that flows during austral summer). Garwood delta sediments contain LGM-aged algal mats, carbonates, phyllosilicates, and diatomaceous biomarker beds. Fossil algal mats are largely concentrated in delta foreset/topset beds, while carbonate and diatom-bearing layers are common in bottomsets. Mean annual temperatures have remained well below 273 K in Garwood Valley since delta emplacement, resulting in preservation of the lake deposits as ice-cemented permafrost. Where the active layer (summer thawing) intersects massive buried ice deposits, deltaic and glacial drift sediments are mobilized to form gullies, providing modern examples of cold desert gully formation processes in a high-purity ice substrate. These Antarctic conditions are strongly analogous to the climate and hydrological environment anticipated at Holden and Eberswalde craters

  18. Breakthrough of methyethylketone and benzene vapors in activated carbon fiber beds.

    PubMed

    Huang, Zheng-Hong; Kang, Feiyu; Liang, Kai-Ming; Hao, Jiming

    2003-03-17

    The breakthrough of low concentration methyethylketone (MEK) and benzene vapors in beds packed with rayon-based activated carbon fiber (ACF) with different surface areas was investigated. The breakthrough characteristics depend on the properties of the ACF and the vapors, as well as on the adsorption conditions. The results of dynamic adsorption in an ACF bed were consistent with those of equilibrium adsorption by gravimetric methods. The breakthrough adsorption indicates that ACF, with an appropriate surface area, could be utilized in controlling volatile organic compounds (VOCs) in indoor air.

  19. Remarkable enhancement of O₂ activation on yttrium-stabilized zirconia surface in a dual catalyst bed.

    PubMed

    Richard, Mélissandre; Can, Fabien; Duprez, Daniel; Gil, Sonia; Giroir-Fendler, Anne; Bion, Nicolas

    2014-10-13

    Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane.

  20. An active wound dressing for controlled convective mass transfer with the wound bed.

    PubMed

    Cabodi, Mario; Cross, Valerie L; Qu, Zheng; Havenstrite, Karen L; Schwartz, Suzanne; Stroock, Abraham D

    2007-07-01

    Conventional wound dressings-gauze, plastic films, foams, and gels-do not allow for spatial and temporal control of the soluble chemistry within the wound bed, and are thus limited to a passive role in wound healing. Here, we present an active wound dressing (AWD) designed to control convective mass transfer with the wound bed; this mass transfer provides a means to tailor and monitor the chemical state of a wound and, potentially, to aid the healing process. We form this AWD as a bilayer of porous poly(hydroxyethyl methacrylate) (pHEMA) and silicone; the pHEMA acts as the interface with the wound bed, and a layer of silicone provides a vapor barrier and a support for connecting to external reservoirs and pumps. We measure the convective permeability of the pHEMA sponge, and use this value to design a device with a spatially uniform flow profile. We quantify the global coefficient of mass transfer of the AWD on a dissolvable synthetic surface, and compare it to existing theories of mass transfer in porous media. We also operate the AWD on model wound beds made of calcium alginate gel to demonstrate extraction and delivery of low molecular weight solutes and a model protein. Using this system, we demonstrate both uniform mass transfer over the entire wound bed and patterned mass transfer in three spatially distinct regions. Finally, we discuss opportunities and challenges for the clinical application of this design of an AWD.

  1. An active wound dressing for controlled convective mass transfer with the wound bed.

    PubMed

    Cabodi, Mario; Cross, Valerie L; Qu, Zheng; Havenstrite, Karen L; Schwartz, Suzanne; Stroock, Abraham D

    2007-07-01

    Conventional wound dressings-gauze, plastic films, foams, and gels-do not allow for spatial and temporal control of the soluble chemistry within the wound bed, and are thus limited to a passive role in wound healing. Here, we present an active wound dressing (AWD) designed to control convective mass transfer with the wound bed; this mass transfer provides a means to tailor and monitor the chemical state of a wound and, potentially, to aid the healing process. We form this AWD as a bilayer of porous poly(hydroxyethyl methacrylate) (pHEMA) and silicone; the pHEMA acts as the interface with the wound bed, and a layer of silicone provides a vapor barrier and a support for connecting to external reservoirs and pumps. We measure the convective permeability of the pHEMA sponge, and use this value to design a device with a spatially uniform flow profile. We quantify the global coefficient of mass transfer of the AWD on a dissolvable synthetic surface, and compare it to existing theories of mass transfer in porous media. We also operate the AWD on model wound beds made of calcium alginate gel to demonstrate extraction and delivery of low molecular weight solutes and a model protein. Using this system, we demonstrate both uniform mass transfer over the entire wound bed and patterned mass transfer in three spatially distinct regions. Finally, we discuss opportunities and challenges for the clinical application of this design of an AWD. PMID:17106898

  2. An overview of the issues: physiological effects of bed rest and restricted physical activity

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Bloomfield, S. A.; Greenleaf, J. E.

    1997-01-01

    Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

  3. Synchronous droplets as a test bed for pulsatory active fluids

    NASA Astrophysics Data System (ADS)

    Katsikis, Georgios; Prakash, Manu

    2014-11-01

    Collective behavior in many-body systems has been studied extensively focusing on a wide range of interacting entities including: flocking animals, sedimenting particles and microfluidic droplets among others. Here, we propose an experimental platform to explore an oscillatory active fluid with synchronous ferrofluid droplets immersed in an immiscible carrier fluid in a Hele-Shaw configuration. The droplets are organized and actuated on a 2-D uniform grid through application of a precessive magnetic field. The state of our system is dependent on three parameters: the grid occupancy with fluid droplets, the grid geometry and the magnetic field. We study the long range orientational order of our system over a range of those parameters by tracking the motion of the droplets and analyzing the PIV data of the carrier fluid flow. Numerical simulations are juxtaposed with experimental data for prediction of the system's behavior.

  4. Using computer models to design gully erosion control structures for humid northern Ethiopia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classic gully erosion control measures such as check dams have been unsuccessful in halting gully formation and growth in the humid northern Ethiopian highlands. Gullies are typically formed in vertisols and flow often bypasses the check dams as elevated groundwater tables make gully banks unstable....

  5. An analysis of mussel bed habitats in the Dutch Wadden Sea

    NASA Astrophysics Data System (ADS)

    Brinkman, A. G.; Dankers, N.; van Stralen, M.

    2002-04-01

    A habitat suitability analysis for littoral mussel beds in the Dutch Wadden Sea was carried out. The analysis was based on the presence of mussel beds in the years 1960-1970, and a number of environmental characteristics: wave action, flow velocity, median grain size, emersion times and distance to a gully border. The habitat model describes mussel bed appearance quantitatively. It predicts the distribution of mussel beds quite well, as well as the distribution of spatfall in the years 1994 and 1996. From the analysis we found that wave action (maximum orbital velocity) was the main structuring factor. A low orbital velocity was preferred. Neither very low, nor maximum flow velocities were favourable for mussel beds. Very coarse sands or silty environments were not preferred. Sites close to the low water line showed lower mussel bed appearance; when emersion time was above 50% , hardly any mussel beds could be found. The habitat suitability analysis and the construction of a habitat suitability map was performed in the framework of the discussions on a further or reduced exploitation of the tidal flats in the Dutch Wadden Sea by cockle and mussel fishery activities.

  6. Evaluation of fructooligosaccharides separation using a fixed-bed column packed with activated charcoal.

    PubMed

    Kuhn, Raquel Cristine; Mazutti, Marcio A; Albertini, Lilian Buoro; Filho, Francisco Maugeri

    2014-05-25

    Recent studies have shown that the chromatographic separation of mixtures of saccharides may be improved by making use of activated charcoal, a promising low cost material for the separation of sugars, including fructooligosaccharides. In this work, the development of a methodology to separate fructooligosaccharides from glucose, fructose and sucrose, using a fixed bed column packed with activated charcoal is proposed. The influence of temperature, eluant concentration and step gradients were evaluated to increase the separation efficiency and fructooligosaccharide purity. The final degree of fructooligosaccharide purification and separation efficiency were about 94% and 3.03 respectively, using ethanol gradient concentration ranging from 3.5% to 15% (v/v) at 40°C. The fixed bed column packed with the activated charcoal was shown to be a promising alternative for sugar separation, mainly those rich in fructooligosaccharides, leading to solutions of acceptable degrees of purification.

  7. Morphology and hydrodynamics of wave-cut gullies

    NASA Astrophysics Data System (ADS)

    Priestas, A. M.; Fagherazzi, S.

    2011-08-01

    Wave-cut gullies are sub-triangular incisions common along deteriorating marsh scarps. Wave gullies may be equispaced to quasi-equispaced and enlarge in time, incising the marsh boundary. A high resolution survey is provided for ten wave gullies formed along the chenier plain of the Rockefeller Wildlife Refuge, Louisiana, USA. The measurements capture the morphologic character, evolution, and erosion rates of wave-cut gullies over a two month period. The data relate changes in morphology to geometric factors and shoreline retreat. Finally, the first analysis of wave data measured by acoustic Doppler velocity profilers is presented to show how propagating waves are transformed inside a wave-cut gully in order to describe the processes leading to their formation. Results show that waves of intermediate period (4-6 s) yield very strong swash currents that hit the gully head, detaching marsh substrate and triggering headward erosion. A conceptual model of wave gully evolution is presented as an explanation for this non-uniform, episodic shoreline erosion.

  8. Gully types in Sacovǎt catchment, Moldavian Plateau, Eastern Romania

    NASA Astrophysics Data System (ADS)

    Andrei, Adrian; Niculita, Mihai

    2016-04-01

    Moldavian Plateau, Eastern Romania is an area where soil erosion is a widespread phenomenon, given the dissected topography, patterns of land use and climate. Gully erosion plays an important role in the soil erosion processes. We have used a high resolution DEMs, high resolution satellite imagery and old aerial images to delineate gullies in the Șacovâț catchment. This catchment has a surface of 314 kmp from which 17 kmp are covered by gullies, resulting a density of 0.05%. We have identified various gully types: continuous and discontinuous, bank gullies, hillslope gullies, road and path gullies and relict gully systems. Road and path gullies have small dimensions, under 2000 sqm, 2 to 5 m in width, up to 500 m in length, 1-2 m in depth, and can be discontinuous. Bank gullies have under 2000 sqm, up to 2000 sqm in surface and up to 500 m in length. Their depth can be similar to bank height, up to 5 m. Hillslope gullies have under 1 km in length, under 100 000 sqm surface, up to 3 in depth and around 20 m channel width. Small hillslope gullies (1000 to 2000 sqm) are in general discontinuous. Relict gully systems have are big dimensions (300 000 to 1 000 000 sqm surface, widths of the channel up to 250 m, 1 to 3 km length, and up to 25 m depth of the channel) and usually present dendritic patterns, with newer bank and hillslope gullies which are hydrologically and morphologically connected to the relict gully channel. Is usual for these gullies to have the channel filled with bank failures and landslides triggered by its deepening. The gullies from Șacovǎț catchment are in continuous evolution, the relict gullies needing dating while the fresh gullies needing monitoring, especially in the context of climate and land use changes due to deforestation.

  9. Gullies and Layers in Crater Wall in Newton

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This dramatic view of gullies emergent from layered outcrops occurs on the wall of a crater within the much larger impact basin, Newton. Newton Crater and its surrounding terrain exhibit many examples of gullies on the walls of craters and troughs. The gullies exhibit meandering channels with fan-shaped aprons of debris located downslope. The gullies are considered to have been formed by erosion--both from a fluid (such as water) running downslope, and by slumping and landsliding processes driven by the force of gravity. This picture was obtained by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in March 2001; it is illuminated from the upper left and covers an area 3 km (1.9 mi) across.

  10. Low-land Gully Formation in the Amhara Region, Ethiopia

    NASA Astrophysics Data System (ADS)

    Rijkee, Pim; Keesstra, Saskia; Mekonnen Gethahun, Mulatie

    2015-04-01

    Land degradation and related processes such as gullying, flooding and sedimentation, are global phenomena. Their economic consequences however are more severe in developing countries, which lack resources for prevention and mitigation. In Ethiopia, therefore, gully erosion as a form of land degradation is a prime issue. Over the past decade, gullies have formed in the foothills of the Minizr sub-catchment in the highlands of North-Western Ethiopia. Local extension workers have reported increased gully growth rates in the past five years in the downslope foothill areas. This study answers the following questions: has the gully growth rate indeed increased over the past five years compared to historical rates? What is the mechanism behind gully formation in the study area? In addition, this study looked at three possible root causes for increased erosion rates: changing land use, an increase in the ground water level, and the implementation of soil and water conservation measures in the watershed of the study area. The merit of this study is twofold. First, it shows the applicability of a fast, accessible and accurate way to digitally represent gullies through the use of video footage and photogrammetry. Secondly, it shows the dominant processes in gully formation in the area, allowing for a justified selection of measures to halt further gully growth and rehabilitate existing gullies. Two medium and one large gully were selected for detailed analysis. All gullies were located in gently-sloped areas (0-5%), with Vertisol-dominated soils. Gully shape and volume were derived using terrestrial photogrammetry in AgiSoft PhotoScan Professional. Still frames exported from video footage served as input. Approximately 30 points per gully were sampled weekly for soil moisture content over the course of September, November, and December 2014. In addition, the sites were checked for signs of subsurface flow at the end of the rainy season and again 3 months into the dry season

  11. 24. LOOKING SOUTHEAST UP A GULLY DEEPENED BY TERMINAL WATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. LOOKING SOUTHEAST UP A GULLY DEEPENED BY TERMINAL WATER FROM NORTH BRANCH, PRAIRIE CITY DITCH. - Natomas Ditch System, Rhodes Ditch, West of Bidwell Street, north of U.S. Highway 50, Folsom, Sacramento County, CA

  12. Impact of land-levelling measures on gully and soil erosion analysed by rainfall simulation and UAV remote sensing data in the Souss Basin, Morocco

    NASA Astrophysics Data System (ADS)

    Peter, Klaus Daniel; d'Oleire-Oltmanns, Sebastian; Ries, Johannes B.; Marzolff, Irene; Hssaine, Ali Ait

    2013-04-01

    Since the 16th century with the rise and fall of sugar production, the Souss basin, situated between High and Anti-Atlas, is affected by gully erosion due to the deforestation of Argan trees. Nowadays, it is one of the most intensive agricultural regions of Morocco. On its sedimentary fans and alluvial terraces, a very dynamic land use change is going on since the early 1960s with transformations of traditional agriculture into agro-industrial plantations of citrus fruits, bananas and vegetables irrigated by deep aquifer groundwater. The implementation of land use change and further expansion of plantations into former agriculturally unsuitable marginal land is accomplished today by land-levelling measures with heavy machinery. The levelling of badland areas and the infilling of existing gully systems lead to changes and disconnections of the drainage system and watersheds on the sedimentary fans. The aim of this study is the investigation of the influence of land-levelling measures and gully infilling on recent erosion rates and on both the re-activation of old and the initiation of new gully systems. An approach combining punctual process analysis through experimental rainfall simulation and gully mapping as well as volume quantification analysing on a local scale using unmanned aerial vehicle (UAV) remote sensing data was applied to relate runoff and sediment production in the gully catchment to current gully erosion rates. For conducting the rainfall simulations a small portable nozzle rainfall simulator with a rainfall intensity of 40 mm h-1 was used. We applied an autopiloted UAV for the monitoring of gullies with small-format aerial photography. Photogrammetric image processing enables the creation of Digital Terrain Models (DTMs) and ortho-image mosaics with very high (centimetre) resolution. Results of the experimental geomorphological fieldwork show a significant increase of mean runoff coefficients and mean sediment loads (1.4 and 3.5 times higher

  13. Use of wood-based materials in beef bedded manure packs: 2. Effect on odorous volatile organic compounds, odor activity value, , and nutrient concentrations.

    PubMed

    Spiehs, Mindy J; Brown-Brandl, Tami M; Berry, Elaine D; Wells, James E; Parker, David B; Miller, Daniel N; Jaderborg, Jeffrey P; DiCostanzo, Alfred

    2014-07-01

    The objectives of this study were to determine the effects of three types of wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, and green cedar chips) and corn stover on the concentration of odorous volatile organic compounds (VOCs) and total in bedded pack material. Four bedded packs of each bedding material were maintained for two 42-d periods ( = 32; eight replicates/bedding material). Straight- and branched-chained fatty acids, aromatic compounds, and sulfide compounds were measured from the headspace above each bedded pack. Green cedar bedding had the highest concentration of odorous VOCs, and pine chip bedding had the lowest ( < 0.01). Calculated odor activity values were highest for green cedar bedding, followed by dry cedar, corn stover, and pine chip bedding. As the bedded packs aged, the concentration of odorous VOCs increased, particularly in the bedded packs containing green cedar chips and dry cedar chips. Total concentrations increased from Days 0 to 21 and then began to decline and were similar among all bedding materials ( < 0.10). Results of this study indicate that producers using a long-term bedded pack management in their facility may benefit from using pine chips because they do not appear to increase odor over time. Cedar-based bedding materials may be better suited for a scrape-and-haul system, where the bedded pack is removed after 1 or 2 wk. Total concentrations did not differ between any of the four bedding materials over time. PMID:25603068

  14. Analysis of experimental studies on gully erosion: a global review

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Gómez, Jose A.

    2015-04-01

    Research on gully erosion has increased significantly in the last decades. Despite the growing interest on the topic, relevant knowledge gaps still remain a challenge for gully erosion researchers (Poesen, 2011). Moreover, many of these studies are mainly descriptive, with little quantitative data allowing a comparison of the severity of the processes among different environments and conditions. The aim of this communication is to analyse the available experimental data in gully erosion literature involving quantitative information from the Web of Science datasets. Our objective is to investigate relevant trends of this type of erosion on the world scale. We have evaluated the role of gully erosion in the overall soil losses as well as the magnitude of the morphological variables. Also, we analysed the characteristics of image-based and field surveys regarding the technique employed, duration and data collection frequency. In this communication, we intend to provide insights on the evolution of gully erosion research up to the present moment in order to gain perspectives on the design of future efforts in the topic. References Poesen, J. 2011. Challenges in gully erosion research. Landform Analysis, Vol. 17: 5-9.

  15. Including physical and biological soil crusts properties in gully prediction

    NASA Astrophysics Data System (ADS)

    Gay, A.; Cerdan, O.; Desprats, J. F.; Malam Issa, O.; Valentin, C.; Rajot, J. L.; Descroix, L.

    2012-04-01

    In Sahelian region, concentrated overland flow often leads to the formation of gullies. Although this phenomenon is widespread in those regions, research efforts are still needed to be able to model their spatial distribution and the role of the different parameters involved in this process. In this context, the objectives of this study are twofold. The first step is to investigate to what extent the role of Sahelian soil surface crusts (biological and/or physical) on soil surface infiltrability and detachment affect the formation and development of gullies. The second step is to integrate the results of these investigations in a simple geomorphological model to predict gully location at the watershed scale. The evaluation of the resulting model on two test catchments demonstrated that the integration of soil crusting is a key parameter to insure the quality and relevance of gully prediction. The model is able to distinguish between two types of gullies, those whose width range between 0.5m and 4m and those whose width exceeds 4m. The application of the model at the regional scale is however limited by the resolution of available regional digital elevation model (i.e. the 90m resolution SRTM DEM) which only permits the prediction of large gullies (width > 4m).

  16. Changes of the porous structure of activated carbons applied in a filter bed pilot operation.

    PubMed

    Gauden, P A; Szmechtig-Gauden, E; Rychlicki, G; Duber, S; Garbacz, J K; Buczkowski, R

    2006-03-15

    The paper investigates the changes in porosity (i.e., in the accessible adsorption capacity of carbonaceous adsorbents for pollutants during filter bed maturation) of three activated carbons applied in a filter bed pilot operation. The results of this investigation may help to reduce operating costs, increase granular activated carbon bed life, maximize the useful life of biofilters, and understand the mechanism of water purification by carbon adsorbents. The analysis of the pore structure was limited to the first year of service of the beds, since this was when the largest decrease in the available pore capacity occurred. Low-temperature nitrogen adsorption isotherms were used to evaluate the structural parameters and pore size distributions (PSDs) of carbon samples (virgin (reference) and mature adsorbents for different periods of water treatment) on the basis of the Nguyen and Do (ND) method and density functional theory (DFT). These results were compared with small-angle X-ray scattering (SAXS) investigations (PSDs calculated by Glatter's indirect transformation method (ITP)). The results show that in general, the ND and ITP methods lead to almost the same qualitative distribution curve behavior. Moreover, the enthalpy of immersion in water, mercury porosimetry, densities (true and apparent), and the analysis of ash are reported and compared to explain the decrease in adsorptive capacity of the carbons investigated. On the other hand, the efficacy of TOC (total organic carbon, i.e., a quantity describing the complex matrix of organic material present in natural waters) removal and the bacteria count were analyzed to explain the role of adsorption in the elimination of contaminants from water. Finally, a mechanism of organic matter removal was suggested on the basis of the above-mentioned experimental data and compared with mechanisms reported by other authors. PMID:16198363

  17. Mechanisms of granular activated carbon anaerobic fluidized-bed process for treating phenols wastewater.

    PubMed

    Lao, Shan-gen

    2002-01-01

    Granular activated carbon (GAC) anaerobic fluidized-bed reactor was applied to treating phenols wastewater. When influent phenol concentration was 1000 mg/L, volume loadings of phenol and CODCr were 0.39 kg/(m3.d) and 0.98 kg/(m3.d), their removal rates were 99.9% and 96.4% respectively. From analyzing above results, the main mechanisms of the process are that through fluidizing GAC, its adsorption is combined with biodegradation, both activities are brought into full play, and phenol in wastewater is effectively decomposed. Meanwhile problems concerning gas-liquid separation and medium plugging are well solved. PMID:11887310

  18. A critical discussion on the applicability of Compound Topographic Index (CTI) for predicting ephemeral gully erosion

    NASA Astrophysics Data System (ADS)

    Casalí, Javier; Chahor, Youssef; Giménez, Rafael; Campo-Bescós, Miguel

    2016-04-01

    The so-called Compound Topographic Index (CTI) can be calculated for each grid cell in a DEM and be used to identify potential locations for ephemeral gullies (e. g.) based on land topography (CTI = A.S.PLANC, where A is upstream drainage area, S is local slope and PLANC is planform curvature, a measure of the landscape convergence) (Parker et al., 2007). It can be shown that CTI represents stream power per unit bed area and it considers the major parameters controlling the pattern and intensity of concentrated surface runoff in the field (Parker et al., 2007). However, other key variables controlling e.g. erosion (e. g. e.) such as soil characteristics, land-use and management, are not had into consideration. The critical CTI value (CTIc) "represents the intensity of concentrated overland flow necessary to initiate erosion and channelised flow under a given set of circumstances" (Parker et al., 2007). AnnAGNPS (Annualized Agriculture Non-Point Source) pollution model is an important management tool developed by (USDA) and uses CTI to locate potential ephemeral gullies. Then, and depending on rainfall characteristics of the period simulated by AnnAGNPS, potential e. g. can become "actual", and be simulated by the model accordingly. This paper presents preliminary results and a number of considerations after evaluating the CTI tool in Navarre. CTIc values found are similar to those cited by other authors, and the e. g. networks that on average occur in the area have been located reasonably well. After our experience we believe that it is necessary to distinguish between the CTIc corresponding to the location of headcuts whose migrations originate the e. g. (CTIc1); and the CTIc necessary to represent the location of the gully networks in the watershed (CTIc2), where gully headcuts are located in the upstream end of the gullies. Most scientists only consider one CTIc value, although, from our point of view, the two situations are different. CTIc1 would represent the

  19. Sediment storage dam: A structural gully erosion control and sediment trapping measure, northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Mekonnen, Mulatie; Keesstra, Saskia; Baartman, Jantiene; Ritsema, Coen

    2014-05-01

    Gully erosion is a prime problem in Ethiopia. This study assessed the severity of gully erosion and the role of sediment storage dams (SSD) in restoring gullies and preventing further gully development, its sediment trapping efficacy (STE) and its capacity in converting degraded gully lands to productive land. On average 2.5 m deep, 6.6 m wide and 28.3 m long gullies were formed in Minizr watershed, northwest Ethiopia, in 2013. Concentrated surface runoff, traditional ditches, graded terraces without suitable water ways and road construction are the main causes of such serious gully erosion. Over grazing, tunnel flow and lack of proper immediate gully treatment actions after gully initiation are found to be additional causes of the problem. Gully erosion was also found as the major source of sediment for downstream rivers and water reservoirs. The annual volume of soil eroded from only four gullies was 1941.3 m3. To control gully erosion, SSDs were found to be important physical structures, which can trap significant amount of sediment within gullies and they can convert unproductive gully land to productive agricultural land for fruit and crop production. Eight SSDs trapped about 44*103 m3 of sediment within 2 to 8 years. Two representative SSDs constructed using gabion and stone were tested for their STE. Results showed that their efficacy was 74.1% and 66.4% for the gabion and stone SSDs, respectively. Six of the older SSDs were already full of sediment and created 0.75 ha of productive land within 2 to 8 years. SSDs best fits to treat large size and deep gullies where other gully control measures, check dams, could not function well. To prevent gully formation, controlling its causes that is avoiding traditional ditches, practicing grassed water ways to safely remove runoff water from graded terraces, integrated watershed and road side management practices are important solutions. KEY WORDS: Sediment storage dam, gully erosion, sediment trapping efficacy

  20. AnnAGNPS GIS-based tool for watershed-scale identification and mapping of cropland potential ephemeral gullies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The formation of ephemeral gullies in agricultural fields has been recognized as an important source of sediment contributing to environmental degradation and compromising crop productivity. Methodologies are being developed for assessing gully formation and gully sediment yield. The Annualized Agri...

  1. Evaluating time dynamics of topographic threshold relations for gully initiation

    NASA Astrophysics Data System (ADS)

    Hayas, Antonio; Vanwalleghem, Tom; Poesen, Jean

    2016-04-01

    Gully erosion is one of the most important soil degradation processes at global scale. However, modelling of gully erosion is still difficult. Despite advances in the modelling of gully headcut rates and incision rates, it remains difficult to predict the location of gully initiation points and trajectories. In different studies it has been demonstrated that a good method of predicting gully initiation is by using a slope (S) - area (A) threshold. Such an S-A relation is a simple way of estimating the critical discharges needed to generate a critical shear stress that can incise a particular soil and initiate a gully. As such, the simple S-A threshold will vary if the rainfall-runoff behaviour of the soil changes or if the soil's erodibility changes. Over the past decades, important agronomic changes have produced significant changes in the soil use and soil management in SW Spain. It is the objective of this research to evaluate how S-A relations for gully initiation have changed over time and for two different land uses, cereal and olive. Data was collected for a gully network in the Cordoba Province, SW Spain. From photo-interpretation of historical air photos between 1956 and 2013, the gully network and initiation points were derived. In total 10 different time steps are available (1956; 1977; 1984; 1998; 2001; 2004; 2006; 2008; 2010; 2013). Topographical thresholds were extracted by combining the digitized gully network with the DEM. Due to small differences in the alignment of ortophotos and DEM, an optimization technique was developed in GIS to extract the correct S-A value for each point. With the S-A values for each year, their dynamics was evaluated as a function of land use (olive or cereal) and in function of the following variables in each of the periods considered: • soil management • soil cover by weeds, where weed growth was modeled from the daily soil water balance • rainfall intensity • root cohesion, , where root growth was modeled from

  2. Melt water-driven gully formation in Moni Crater, Mars

    NASA Astrophysics Data System (ADS)

    Glines, N. H.; Gulick, V. C.; Freeman, P. M.

    2015-12-01

    The southern mid-latitude 5-km diameter Moni Crater (47S, 18.5E) in Noachis Terra is typical of many small craters of this latitude, containing both gullies on its walls and arcuate ridges on its floor. Interpreted by Howard (2003) and others as remnant terminal moraines, these ridges are located at the distal margins of the gullies' debris aprons, suggesting a possible association in their formation. Our results suggest that these arcuate ridges might result from the downslope movement of ice-rich deposits that pushed pre-existing ice-rich crater floor deposits into a moraine-like ridge. The pre-existing floor deposits can be interpreted to be a form of sublimated Concentric Crater Fill (CCF), which would have been among the first ice deposits to erode the Moni Crater walls. If we assume the arcuate ridges to be glacial moraines, then we can also assume the same processes that elevated the ridges also provided melt water to form the gullies. There is evidence that water and ice deposit-related processes incised the gully headwalls, exposing bedrock, plucking boulders, and initiating fractures, through ice-wedging or surface abrasion. HiRISE images (~25cm/pixel) show shallow gullies extending several tens of meters beyond the crater rim, exploiting possible fractures or lineation in the rock. Melt water from these ice deposits, or snow melt, is a potential gully formation mechanism that would be consistent with the shallow runoff-like drainage morphology extending above the gully alcoves and beyond the crater rim. An initial phase of rapid melt water flows would also explain the wider degraded remnant channels we see on the crater slopes. The more gradual melting of ice frozen around headwall rocks could explain a secondary phase of melt water flows that form the more-recent channels.

  3. A critical discussion on the applicability of Compound Topographic Index (CTI) for predicting ephemeral gully erosion

    NASA Astrophysics Data System (ADS)

    Casalí, Javier; Chahor, Youssef; Giménez, Rafael; Campo-Bescós, Miguel

    2016-04-01

    The so-called Compound Topographic Index (CTI) can be calculated for each grid cell in a DEM and be used to identify potential locations for ephemeral gullies (e. g.) based on land topography (CTI = A.S.PLANC, where A is upstream drainage area, S is local slope and PLANC is planform curvature, a measure of the landscape convergence) (Parker et al., 2007). It can be shown that CTI represents stream power per unit bed area and it considers the major parameters controlling the pattern and intensity of concentrated surface runoff in the field (Parker et al., 2007). However, other key variables controlling e.g. erosion (e. g. e.) such as soil characteristics, land-use and management, are not had into consideration. The critical CTI value (CTIc) "represents the intensity of concentrated overland flow necessary to initiate erosion and channelised flow under a given set of circumstances" (Parker et al., 2007). AnnAGNPS (Annualized Agriculture Non-Point Source) pollution model is an important management tool developed by (USDA) and uses CTI to locate potential ephemeral gullies. Then, and depending on rainfall characteristics of the period simulated by AnnAGNPS, potential e. g. can become "actual", and be simulated by the model accordingly. This paper presents preliminary results and a number of considerations after evaluating the CTI tool in Navarre. CTIc values found are similar to those cited by other authors, and the e. g. networks that on average occur in the area have been located reasonably well. After our experience we believe that it is necessary to distinguish between the CTIc corresponding to the location of headcuts whose migrations originate the e. g. (CTIc1); and the CTIc necessary to represent the location of the gully networks in the watershed (CTIc2), where gully headcuts are located in the upstream end of the gullies. Most scientists only consider one CTIc value, although, from our point of view, the two situations are different. CTIc1 would represent the

  4. Origin and age of erosional gullies and ridges in loess of central Alaska--Evidence of ancient global warming

    SciTech Connect

    Pewe, T.L. . Geology Dept.)

    1992-01-01

    The lower and especially middle slopes of many of the rolling hills of the Yukon-Tanana Upland are blanketed with 3 to 20 m of olive gray, airfall, massive loess which is dissected by parallel gullies 10--15 m deep and 100--200 m long that trend downslope. The gullies and ridges occur over hundreds of square kilometers. It is believed the eroded and gullied loess topography originated during the last interglacial of 125 ka. The climatic warming led to: (1) melting of the ground ice in permafrost and thermokarst activity, and (2) to greatly reduced loess deposition. The author believes that most of the water to initiate loess cutting came from the melting of the great amount of ground ice in the permafrost. The last interglacial time was warm enough to melt the ground ice and initiate catastrophic thermokarst activity in easily erodible loess on hillsides. If the gullying had been in Holocene time, the ridges and gullies would be more sharp sided and the ridges relatively flat-topped, as is characteristic of trenched loess, even after centuries. On the other hand, gullies and ridges formed early during the Eva Interglacial would tend to be subdued by creep and solifluction during the 100,000 year Wisconsin cold interval. Such is illustrated by the downbending of loess and tephra on the sides of loess ridges. If the loess ridges were formed in Holocene time, they would include horizontal loess deposits of Wisconsin and perhaps early Holocene times inasmuch as they would be covering a nongullied topography. Examination reveals that there are no Wisconsin and Holocene loess deposits on the steep side slopes of the uppermost part of the ridges and other erosional remnants. The Subarctic Brown Forest soil is interglacial and, started to form anywhere from 10,000 to 8,000 years ago. The soil profile developed on the pre-soil ridge topography; therefore, the time of ridge and gully formation is pre-10,000 years.

  5. Influence of Gully Erosion Control on Amphibian and Reptile Communities within Riparian Zones of Channelized Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian zones of streams in northwestern Mississippi have been impacted by agriculture, channelization, channel incision, and gully erosion. Riparian gully formation has resulted in the fragmentation of remnant riparian zones within agricultural watersheds. One widely used conservation practice for...

  6. Biomechanics-based active control of bedding support properties and its influence on sleep.

    PubMed

    Van Deun, D; Verhaert, V; Willemen, T; Wuyts, J; Verbraecken, J; Exadaktylos, V; Haex, B; Vander Sloten, J

    2012-01-01

    Proper body support plays an import role in the recuperation of our body during sleep. Therefore, this study uses an automatically adapting bedding system that optimises spinal alignment throughout the night by altering the stiffness of eight comfort zones. The aim is to investigate the influence of such a dynamic sleep environment on objective and subjective sleep parameters. The bedding system contains 165 sensors that measure mattress indentation. It also includes eight actuators that control the comfort zones. Based on the measured mattress indentation, body movements and posture changes are detected. Control of spinal alignment is established by fitting personalized human models in the measured indentation. A total of 11 normal sleepers participated in this study. Sleep experiments were performed in a sleep laboratory where subjects slept three nights: a first night for adaptation, a reference night and an active support night (in counterbalanced order). Polysomnographic measurements were recorded during the nights, combined with questionnaires aiming at assessing subjective information. Subjective information on sleep quality, daytime quality and perceived number of awakenings shows significant improvements during the active support (ACS) night. Objective results showed a trend towards increased slow wave sleep. On the other hand, it was noticed that % N1-sleep was significantly increased during ACS night, while % N2-sleep was significantly decreased. No prolonged N1 periods were found during or immediately after steering.

  7. Biophysical and economic assessment of a community-based rehabilitated gully in the Ethiopian highlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the last fifty years, sediment concentrations in the Ethiopian highlands have increased two- to three-fold. The current severity of gully erosion is a major cause of increased sediment loads, but gully rehabilitation has proven to be challenging, with limited success. This paper describes gully r...

  8. Dynamic adsorption of organic solvent vapors onto a packed bed of activated carbon cloth

    SciTech Connect

    Huang, C.C.; Lin, Y.C.; Lu, F.C.

    1999-02-01

    The adsorption behavior of organic compound vapors onto a packed bed of activated carbon cloth (ACC) has been investigated. Three types of ACCs have been employed: KF1500, FT200-20, and E-ACC. The volatile organic compounds (VOCs) used in this study are acetone, dichloromethane, acrylonitrile, and n-hexane. The operating parameters studied are temperature of adsorber, weight of ACC, relative humidity of fluid, inlet concentration of VOCs, and total volumetric flow rate of gas stream. A simple theoretical model, originally introduced by Yoon and Nelson, has been utilized to simulate the breakthrough curve of VOC vapor on an adsorption column packed with activated carbon cloth. A modified model is proposed to predict the adsorption behavior of an adsorber at different temperatures.

  9. Hillslope gullying in the Solway Firth — Morecambe Bay region, Great Britain: Responses to human impact and/or climatic deterioration?

    NASA Astrophysics Data System (ADS)

    Chiverrell, R. C.; Harvey, A. M.; Foster, G. C.

    2007-02-01

    In the Solway Firth — Morecambe Bay region of Great Britain there is evidence for heightened hillslope instability during the late Holocene (after 3000 cal. BP). Little or no hillslope geomorphic activity has been identified occurring during the early Holocene, but there is abundant evidence for late Holocene hillslope erosion (gullying) and associated alluvial fan and valley floor deposition. Interpretation of the regional radiocarbon chronology available from organic matter buried beneath alluvial fan units suggests much of this geomorphic activity can be attributed to four phases of more extensive gullying identified after 2500-2200, 1300-1000, 1000-800 and 500 cal. BP. Both climate and human impact models can be evoked to explain the crossing of geomorphic thresholds: and palaeoecological data on climatic change (bog surface wetness) and human impact (pollen), together with archaeological and documentary evidence of landscape history, provide a context for addressing the causes of late Holocene geomorphic instability. High magnitude storm events are the primary agent responsible for gully incision, but neither such events nor cooler/wetter climatic episodes appear to have produced gully systems in the region before 3000 cal. BP. Increased gullying after 2500-2200 cal. BP coincides with population expansion during Iron Age and Romano-British times. The widespread and extensive gullying after 1300-1000 cal. BP and after 1000-800 cal. BP coincides with periods of population expansion and a growing rural economy identified during Norse times, 9-10th centuries AD, and during the Medieval Period, 12-13th centuries AD. These periods were separated by a downturn associated with the 'harrying of the north' AD 1069 to 1070. The gullying episode after 500 cal. BP also coincides with increased anthropogenic pressure on the uplands, with population growth and agricultural expansion after AD 1500 following 150 years of malaise caused by livestock and human (the Black Death

  10. Evidence for Methyl-Compound-Activated Life in Coal Bed System 2 km Below Sea Floor

    NASA Astrophysics Data System (ADS)

    Trembath-reichert, E.; Morono, Y.; Dawson, K.; Wanger, G.; Bowles, M.; Heuer, V.; Hinrichs, K. U.; Inagaki, F.; Orphan, V. J.

    2014-12-01

    IODP Expedition 337 set the record for deepest marine scientific drilling down to 2.4 kmbsf. This cruise also had the unique opportunity to retrieve deep cores from the Shimokita coal bed system in Japan with the aseptic and anaerobic conditions necessary to look for deep life. Onboard scientists prepared nearly 1,700 microbiology samples shared among five different countries to study life in the deep biosphere. Samples spanned over 1 km in sampling depths and include representatives of shale, sandstone, and coal lithologies. Findings from previous IODP and deep mine expeditions suggest the genetic potential for methylotrophy in the deep subsurface, but it has yet to be observed in incubations. A subset of Expedition 337 anoxic incubations were prepared with a range of 13C-methyl substrates (methane, methylamine, and methanol) and maintained near in situ temperatures. To observe 13C methyl compound metabolism over time, we monitored the δ13C of the dissolved inorganic carbon (by-product of methyl compound metabolism) over a period of 1.5 years. Elemental analysis (EA), ion chromatograph (IC), 13C volatile fatty acid (VFA), and mineral-associated microscopy data were also collected to constrain initial and endpoint conditions in these incubations. Our geochemical evidence suggests that the coal horizon incubated with 13C-methane showed the highest activity of all methyl incubations. This provides the first known observation of methane-activated metabolism in the deep biosphere, and suggests there are not only active cells in the deeply buried terrigenous coal bed at Shimokita, but the presence of a microbial community activated by methylotrophic compounds.

  11. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas. PMID:27163861

  12. How to dose powdered activated carbon in deep bed filtration for efficient micropollutant removal.

    PubMed

    Altmann, Johannes; Ruhl, Aki S; Sauter, Daniel; Pohl, Julia; Jekel, Martin

    2015-07-01

    Direct addition of powdered activated carbon (PAC) to the inlet of a deep bed filter represents an energy- and space-saving option to remove organic micropollutants (OMPs) during advanced wastewater treatment or drinking water purification. In this lab-scale study, continuous dosing, preconditioning a filter with PAC and combinations thereof were investigated as possible dosing modes with respect to OMP adsorption efficiency. Continuous dosing resulted in decreasing effluent concentrations with increasing filter runtime due to adsorption onto accumulating PAC in the filter bed. Approximately constant removal levels were achieved at longer filter runtimes, which were mainly determined by the dose of fresh PAC, rather than the total PAC amount embedded. The highest effluent concentrations were observed during the initial filtration stage. Meanwhile, preconditioning led to complete OMP adsorption at the beginning of filtration and subsequent gradual OMP breakthrough. PAC distribution in the pumice filter was determined by the loss on ignition of PAC and pumice and was shown to be relevant for adsorption efficiency. Preconditioning with turbulent upflow led to a homogenous PAC distribution and improved OMP adsorption significantly. Combining partial preconditioning and continuous dosing led to low initial effluent concentrations, but ultimately achieved concentrations similar to filter runs without preconditioning. Furthermore, a dosing stop prior to the end of filtration was suitable to increase PAC efficiency without affecting overall OMP removals. PMID:25898248

  13. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas.

  14. Biological activated carbon fluidized-bed system to treat gasoline-contaminated groundwater

    SciTech Connect

    Voice, T.C.; Zhao, X.; Shi, J.; Hickey, R.F.

    1995-12-31

    An integrated biological granular activated carbon fluidized-bed reactor (GAC-FBR) and a biological fluidized-bed reactor (FBR) charged with nonactivated carbon were evaluated for treating groundwater contaminated with the gasoline constituents benzene, toluene, and xylenes (BTX). The systems were studied under several conditions including startup, steady-state, and step-load increase conditions. Development of bioactivity in the GAC-FBR was faster than in the FBR using a nonactivated carbon biomass carrier. Under two steady-state conditions, organic loading rates of 3 and 6 kg-chemical oxygen demand (COD)/m{sup 3}-day, BTX removal was similar in the two systems with more than 90% of applied BTX removed. The GAC-FBR produced superior effluent quality during step organic load rate (OLR) increases compared to the FBR. The results from an extremely high step OLR increase show the formation of partial oxidization products from the degradation of BTX. Significant adsorption capacity was still observed after the biofilm developed, although capacity gradually decreased over a 6-month period of operation to approximately 50% of its original value.

  15. Trace Elements Affect Methanogenic Activity and Diversity in Enrichments from Subsurface Coal Bed Produced Water

    PubMed Central

    Ünal, Burcu; Perry, Verlin Ryan; Sheth, Mili; Gomez-Alvarez, Vicente; Chin, Kuk-Jeong; Nüsslein, Klaus

    2012-01-01

    Microbial methane from coal beds accounts for a significant and growing percentage of natural gas worldwide. Our knowledge of physical and geochemical factors regulating methanogenesis is still in its infancy. We hypothesized that in these closed systems, trace elements (as micronutrients) are a limiting factor for methanogenic growth and activity. Trace elements are essential components of enzymes or cofactors of metabolic pathways associated with methanogenesis. This study examined the effects of eight trace elements (iron, nickel, cobalt, molybdenum, zinc, manganese, boron, and copper) on methane production, on mcrA transcript levels, and on methanogenic community structure in enrichment cultures obtained from coal bed methane (CBM) well produced water samples from the Powder River Basin, Wyoming. Methane production was shown to be limited both by a lack of additional trace elements as well as by the addition of an overly concentrated trace element mixture. Addition of trace elements at concentrations optimized for standard media enhanced methane production by 37%. After 7 days of incubation, the levels of mcrA transcripts in enrichment cultures with trace element amendment were much higher than in cultures without amendment. Transcript levels of mcrA correlated positively with elevated rates of methane production in supplemented enrichments (R2 = 0.95). Metabolically active methanogens, identified by clone sequences of mcrA mRNA retrieved from enrichment cultures, were closely related to Methanobacterium subterraneum and Methanobacterium formicicum. Enrichment cultures were dominated by M. subterraneum and had slightly higher predicted methanogenic richness, but less diversity than enrichment cultures without amendments. These results suggest that varying concentrations of trace elements in produced water from different subsurface coal wells may cause changing levels of CBM production and alter the composition of the active methanogenic community. PMID

  16. Monitoring endocrine activity in kraft mill effluent treated by aerobic moving bed bioreactor system.

    PubMed

    Chamorro, S; Pozo, G; Jarpa, M; Hernandez, V; Becerra, J; Vidal, G

    2010-01-01

    A Moving Bed Bioreactor (MBBR) was operated at three different hydraulic retention times for a period of 414 days. The fate of the extractive compounds and the estrogenic activity of the Pinus radiata kraft mill effluents were evaluated using Yeast Estrogen Screen (YES) and gas chromatography - mass spectrometry (GC-MS) detection. Results show that the MBBR reactor is able to remove between 80-83% of estrogenic activity present in the kraft mill Pinus radiata influent, where the values of the effluent's estrogenic activity ranged between 0.123-0.411 ng L(-1), expressed as estrogenic equivalent (EEqs) of 17-a-ethynylestradiol (EE2 eq.). Additionally, the biomass of the MBBR reactor accumulated estrogenic activity ranging between 0.29-0.37 ng EEqs EE2 during the different Hydraulic Retention Time (HRT) operations. The main groups present in pulp mills effluents, corresponding to fatty acids, hydrocarbons, phenols, sterols and triterpenes, were detected by solid phase extraction (SPE) and gas chromatography - mass spectrometry (GC-MS). The results suggest that the sterols produce the estrogenic activity in the evaluated effluent. PMID:20595766

  17. Crop structure in a gully catchment and the development of a loess gully (Lublin Upland, E Poland)

    NASA Astrophysics Data System (ADS)

    Mędrek, Karolina; Rodzik, Jan

    2015-04-01

    The study was conducted in a loess gully catchment with an area of 1.23 km2 and height differences of less than 50 m (213-165 m above sea level), located in Kolonia Celejów in the Nałęczów Plateau. This is one of mesoregions of Lublin Upland. In the investigated catchment, loess cover with a thickness of 10-20 m, accumulated during the Vistulian Glaciation, is dissected by a gully system with a depth of 5-15 m and total length of 7.5 km. The gully system is forested in 30% of its area. Until recently, the remaining part of the catchment under agricultural use has been dominated by conventional farming of cereals, potatoes, and sugar beets. Today, 15% of the non-forested area of the catchment is occupied by housing premises, dirt roads, and fallow land, and 45% by orchards with maintained turf, including berry plantations. This type of land management contributes to the retention of precipitation, and protects the soil from flushing. Approximately 20% of the agricultural land is occupied by conventional crops (cereals and root crops), protecting the soil to a moderate degree. Water runoff in the area does not occur every year. Approximately 20% of the agricultural land is currently occupied by cruciferous vegetables (broccoli and cauliflower), decorative shrubs, and orchards without turf in the first 2 years of use. Water and soil runoff from these crops occurs even several times per year. The majority of the material is retained in the lower part of the field, and the water flows into the gully. The crops in the fields adjacent to the ravine have a direct impact on the development of the gully. If the field is located on a raised headland, the flowing water dissects the edge of the gully, and the eroded material is accumulated on the gully bottom. If the field is located in a valley above the gullyhead, the flowing water dissects the bottom of the gully, and the eroded material is discharged outside the catchment.

  18. Radioactive Demonstrations Of Fluidized Bed Steam Reforming (FBSR) With Hanford Low Activity Wastes

    SciTech Connect

    Jantzen, C. M.; Crawford, C. L.; Burket, P. R.; Bannochie, C. J.; Daniel, W. G.; Nash, C. A.; Cozzi, A. D.; Herman, C. C.

    2012-10-22

    Several supplemental technologies for treating and immobilizing Hanford low activity waste (LAW) are being evaluated. One immobilization technology being considered is Fluidized Bed Steam Reforming (FBSR) which offers a low temperature (700-750?C) continuous method by which wastes high in organics, nitrates, sulfates/sulfides, or other aqueous components may be processed into a crystalline ceramic (mineral) waste form. The granular waste form produced by co-processing the waste with kaolin clay has been shown to be as durable as LAW glass. The FBSR granular product will be monolithed into a final waste form. The granular component is composed of insoluble sodium aluminosilicate (NAS) feldspathoid minerals such as sodalite. Production of the FBSR mineral product has been demonstrated both at the industrial, engineering, pilot, and laboratory scales on simulants. Radioactive testing at SRNL commenced in late 2010 to demonstrate the technology on radioactive LAW streams which is the focus of this study.

  19. Modeling of moisture diffusivity, activation energy and energy consumption in fluidized bed drying of rough rice

    NASA Astrophysics Data System (ADS)

    Khanali, Majid; Banisharif, Alireza; Rafiee, Shahin

    2016-01-01

    The present work was an attempt to assess the effective moisture diffusivity, activation energy, and energy consumption of rough rice in a batch fluidized bed dryer. Drying experiments were conducted at drying air temperatures of 50, 60, and 70 °C, superficial fluidization velocities of 2.3, 2.5, and 2.8 m/s, and solids holdup of 1.32 kg. Drying kinetics showed that the whole fluidized bed drying of rough rice occurred in the falling rate period. The effective moisture diffusivity was described by an Arrhenius equation. The evaluated effective moisture diffusivity increased with drying air temperature and superficial fluidization velocity and was found to vary from 4.78 × 10-11 to 1.364 × 10-10 m2/s with R2 higher than 0.9643. The activation energy and the pre-exponential factor of Arrhenius equation were found to be in the range of 36.59-44.31 kJ/mol and 4.71 × 10-5-7.15 × 10-4 m2/s, respectively. Both maximum values of the specific energy consumption of 74.73 MJ/kg and the total energy need of 12.43 MJ were obtained at 60 °C drying air temperature and 2.8 m/s superficial fluidization velocity. Both minimum values of the specific energy consumption of 29.98 MJ/kg and the total energy need of 4.85 MJ were obtained under drying air temperature of 70 °C and superficial fluidization velocity of 2.3 m/s.

  20. Modeling of moisture diffusivity, activation energy and energy consumption in fluidized bed drying of rough rice

    NASA Astrophysics Data System (ADS)

    Khanali, Majid; Banisharif, Alireza; Rafiee, Shahin

    2016-11-01

    The present work was an attempt to assess the effective moisture diffusivity, activation energy, and energy consumption of rough rice in a batch fluidized bed dryer. Drying experiments were conducted at drying air temperatures of 50, 60, and 70 °C, superficial fluidization velocities of 2.3, 2.5, and 2.8 m/s, and solids holdup of 1.32 kg. Drying kinetics showed that the whole fluidized bed drying of rough rice occurred in the falling rate period. The effective moisture diffusivity was described by an Arrhenius equation. The evaluated effective moisture diffusivity increased with drying air temperature and superficial fluidization velocity and was found to vary from 4.78 × 10-11 to 1.364 × 10-10 m2/s with R2 higher than 0.9643. The activation energy and the pre-exponential factor of Arrhenius equation were found to be in the range of 36.59-44.31 kJ/mol and 4.71 × 10-5-7.15 × 10-4 m2/s, respectively. Both maximum values of the specific energy consumption of 74.73 MJ/kg and the total energy need of 12.43 MJ were obtained at 60 °C drying air temperature and 2.8 m/s superficial fluidization velocity. Both minimum values of the specific energy consumption of 29.98 MJ/kg and the total energy need of 4.85 MJ were obtained under drying air temperature of 70 °C and superficial fluidization velocity of 2.3 m/s.

  1. Assessing riparian conservation land management practice impacts on gully erosion in Iowa.

    PubMed

    Zaimes, George N; Schultz, Richard C

    2012-05-01

    Well-established perennial vegetation in riparian areas of agricultural lands can stabilize the end points of gullies and reduce their overall erosion. The objective of this study was to investigate the impacts of riparian land management on gully erosion. A field survey documented the number of gullies and cattle access points in riparian forest buffers, grass filters, annual row-cropped fields, pastures in which the cattle were fenced out of the stream, and continuously, rotationally and intensive rotationally grazed pastures in three regions of Iowa. Gully lengths, depths and severely eroding bank areas were measured. Gullies exhibited few significant differences among riparian management practices. The most significant differences were exhibited between conservation and agricultural management practices, an indication that conservation practices could reduce gully erosion. Changes in pasture management from continuous to rotational or intensive rotational grazing showed no reductions in gully erosion. It is important to recognize that more significant differences among riparian management practices were not exhibited because the conservation and alternative grazing practices had recently been established. As gully formation is more impacted by upland than riparian management, gully stabilization might require additional upland conservation practices. The existence of numerous cattle access points in pastures where cattle have full access to the stream also indicates that these could be substantial sources of sediment for streams. Finally, the gully banks were less important sediment contributors to streams than the streambanks. The severely eroding bank areas in streams were six times greater than those in the gullies in the monitored reaches.

  2. Assessing Riparian Conservation Land Management Practice Impacts on Gully Erosion in Iowa

    NASA Astrophysics Data System (ADS)

    Zaimes, George N.; Schultz, Richard C.

    2012-05-01

    Well-established perennial vegetation in riparian areas of agricultural lands can stabilize the end points of gullies and reduce their overall erosion. The objective of this study was to investigate the impacts of riparian land management on gully erosion. A field survey documented the number of gullies and cattle access points in riparian forest buffers, grass filters, annual row-cropped fields, pastures in which the cattle were fenced out of the stream, and continuously, rotationally and intensive rotationally grazed pastures in three regions of Iowa. Gully lengths, depths and severely eroding bank areas were measured. Gullies exhibited few significant differences among riparian management practices. The most significant differences were exhibited between conservation and agricultural management practices, an indication that conservation practices could reduce gully erosion. Changes in pasture management from continuous to rotational or intensive rotational grazing showed no reductions in gully erosion. It is important to recognize that more significant differences among riparian management practices were not exhibited because the conservation and alternative grazing practices had recently been established. As gully formation is more impacted by upland than riparian management, gully stabilization might require additional upland conservation practices. The existence of numerous cattle access points in pastures where cattle have full access to the stream also indicates that these could be substantial sources of sediment for streams. Finally, the gully banks were less important sediment contributors to streams than the streambanks. The severely eroding bank areas in streams were six times greater than those in the gullies in the monitored reaches.

  3. Evidence for Recent Liquid Water on Mars: Clues Regarding the Relative Youth of Martian Gullies

    NASA Technical Reports Server (NTRS)

    2000-01-01

    How recent is 'recent'? The small martian gullies discovered in Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) pictures of certain craters, troughs, and valleys between latitudes 30o and 70o appear to be geologically young. This means that, on the scale of a planet that is 4.5billion years old, the gullies may be only a few million, or less, years old. The youth of these gullies relative to the history of Mars is indicated by the lack of impact craters--formed by meteors--on the alcoves, channels, or aprons of these features. However, other evidence suggests that the gullies may, in many cases, be much younger than a few million years--in fact, some might be actively seeping water in modern times.

    The first picture, 'Apron Covering Dunes,' shows a deep, prominent martian gully in a south-facing wall in Nirgal Vallis near 29.4oS, 39.1oW. Sunlight illuminates the scene from the upper left. At the bottom of the picture is a series of evenly-spaced, almost parallel ridges. These ridges are dunes created by windblown sand. The apron--the fanlike deposit at the lower end of the deep channel--at this location is seen covering some of the dunes. The sand dunes are thus older than the apron of debris that came from the channel. The dune field has no small meteor impact craters on it, so it, like the gully landforms, is geologically young--yet older than the apron. If the dunes are active in the modern environment--which is uncertain despite the apparent youth of the dunes--then the apron would have had to form within the past few centuries or less. This picture was taken in September 1999.

    The second picture, 'Apron on Polygons,' shows aprons deposited at the base of the south-facing slope in an impact crater at 54.8oS, 342.5oW, in Noachis Terra. The slope and plains surrounding the apron materials have a bumpy pattern of evenly-spaced polygons. Polygonal patterns like this are common in the middle and high latitude regions of Mars, and, like their

  4. Evidence for Recent Liquid Water on Mars: Clues Regarding the Relative Youth of Martian Gullies

    NASA Technical Reports Server (NTRS)

    2000-01-01

    How recent is 'recent'? The small martian gullies discovered in Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) pictures of certain craters, troughs, and valleys between latitudes 30o and 70o appear to be geologically young. This means that, on the scale of a planet that is 4.5billion years old, the gullies may be only a few million, or less, years old. The youth of these gullies relative to the history of Mars is indicated by the lack of impact craters--formed by meteors--on the alcoves, channels, or aprons of these features. However, other evidence suggests that the gullies may, in many cases, be much younger than a few million years--in fact, some might be actively seeping water in modern times.

    The first picture, 'Apron Covering Dunes,' shows a deep, prominent martian gully in a south-facing wall in Nirgal Vallis near 29.4oS, 39.1oW. Sunlight illuminates the scene from the upper left. At the bottom of the picture is a series of evenly-spaced, almost parallel ridges. These ridges are dunes created by windblown sand. The apron--the fanlike deposit at the lower end of the deep channel--at this location is seen covering some of the dunes. The sand dunes are thus older than the apron of debris that came from the channel. The dune field has no small meteor impact craters on it, so it, like the gully landforms, is geologically young--yet older than the apron. If the dunes are active in the modern environment--which is uncertain despite the apparent youth of the dunes--then the apron would have had to form within the past few centuries or less. This picture was taken in September 1999.

    The second picture, 'Apron on Polygons,' shows aprons deposited at the base of the south-facing slope in an impact crater at 54.8oS, 342.5oW, in Noachis Terra. The slope and plains surrounding the apron materials have a bumpy pattern of evenly-spaced polygons. Polygonal patterns like this are common in the middle and high latitude regions of Mars, and, like their

  5. Typical urban gully nitrogen migration in Changchun City, China.

    PubMed

    Song, Yujia; Liu, Huiqing

    2013-12-01

    In this study, Yitong River, which is located in Changchun, a representative city in northeastern China, was selected as the research area. Using position monitoring and field measurements, we quantitatively investigated the migration path and flux of nitrogen in a gully region in Changchun City undergoing rapid urbanization. The results showed that at the Yitong River subwatershed, the total nitrogen input flux was 188 kg/hm(2), the degree of which can be ranked in descending order as fertilizer input > biological immobilization > feed > atmospheric deposition. The total nitrogen output flux was 102.5 kg/hm(2), ranked in descending degree as products > waste output > denitrification > surface runoff. The net nitrogen storage was 85.5 kg/hm(2). The migration path and flux of nitrogen were markedly impacted by human activities, showing an imbalance between input and output, as well as a tendency toward nitrogen accumulation and pollution. The nitrogen budget for the Yitong River subwatershed suggested that more than 50 % of the net anthropogenic nitrogen input was lost to the environment, and about 14.5 % was discharged in rivers, indicating that agricultural and human activities in the basin substantially impact the river water quality and thus alter the nitrogen environmental geochemistry. Reducing the application and improving the efficiency of nitrogenous fertilizer use as well as reclaiming human life waste are efficient approaches to decreasing the nitrogen input flux and environmental accumulation and to promoting the balance between nitrogen input and output. These practices are also effective approaches to reducing non-point source pollution.

  6. Albedo Study of the Depositional Fans Associated with Martian Gullies

    NASA Astrophysics Data System (ADS)

    Craig, J.; Sears, D. W. G.

    2005-03-01

    This work is a two-part investigation of the albedo of the depositional aprons or fans associated with Martian gully features. Using Adobe Systems Photoshop 5.0 software we analyzed numerous Mars Global Surveyor MOC and Mars Odyssey THEMIS images.

  7. Upstream Material Accumulation and Meandering on Present Day Gully Evolution

    NASA Astrophysics Data System (ADS)

    Pasquon, K.; Gargani, J.; Massé, M.; Conway, S. J.; Vincendon, M.; Séjourné, A.

    2016-09-01

    Here we show the present day evolution of a martian gully during the last 4 MY: (1) non-seasonal material accumulation in the alcove, (2) seasonal evolution of meanders, (3) extension of the channel, (4) significant modifications of the debris apron.

  8. Gullies in a Crater Wall in Newton Basin:

    NASA Technical Reports Server (NTRS)

    2002-01-01

    MGS MOC Release No. MOC2-317, 8 August 2002 One of the advantages of having a high resolution camera orbiting Mars is that whole new classes of martian landforms can be revealed. As first described by Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) scientists in June 2000, MOC images of 1.5 to 12 meters per pixel (4.9 to 39 feet per pixel) have done just that--revealed a whole new class of martian landform, the mid-latitude gully. Mid-latitude gullies provide the most compelling evidence--though not conclusively--that Mars may have aquifers of groundwater at shallow depths (less than 500 meters, 1640 ft) below the surface. They are found most commonly on pole-facing slopes in craters and troughs at middle to high latitudes. Where multiple gullies are present, they usually emanate from the same layer in a given crater or trough wall. The gullies shown here occur on the layered north wall of a crater in Newton Basin near 41.8oS, 158.0oW. The picture was obtained by MOC in May 2002. Dark sand dunes are visible at the bottom of the image, especially at the lower right. This view has an aspect ratio of 1.5 to 1; that is, the image covers an area 4.3 km (2.7 mi) from top to bottom and 2.9 km (1.8 mi) from left to right. Nearly all of the craters in Newton Basin have a plethora of similar gullies, suggesting that Newton is the site of an aquifer. Instead of forming by seepage and runoff of groundwater, other researchers have suggested that martian gullies may form by melting of ground ice, melting of surficial snow (under climate conditions different than today), or discharge of carbon dioxide that somehow became buried under the martian surface. None of these alternatives can explain all of the observed attributes of the gullies, especially their associations with specific layers. Seeping water, potentially as a saline brine, remains the most likely explanation.

  9. CO2-driven formation of gullies on Mars

    NASA Astrophysics Data System (ADS)

    Pilorget, Cedric; Forget, François

    2015-11-01

    Since their discovery by the Mars Observer Camera, Martian gullies have attracted considerable attention because they resemble terrestrial debris flows formed by the action of liquid water. This interpretation is now questioned by the discovery of ongoing gully formation occurring in conditions much too cold for liquid water, but with seasonal CO2 frost present and defrosting. However, how a relatively thin seasonal dry ice cover could trigger the formation of decameter large debris flows exhibiting levees and sinuosities as if they were liquid-rich remained mysterious.We have developed an innovative thermo-physical model of the Martian soil able to compute the seasonal evolution of a column composed of an underlying regolith, a CO2 ice layer, and the atmosphere above. Below the surface, in the CO2 ice layer (when present) and in the regolith, the model simultaneously solves the heat conduction, the radiative transfer through the ice as well as the diffusion, condensation and sublimation of CO2 and the related latent heat exchanges.We have found that, during the defrosting season, the pores below the ice layer can be filled with CO2 ice, and subject to extreme pressure variations. The subsequent gas fluxes can destabilize the soil and create gas-lubricated debris flows with the observed geomorphological characteristics of the Martian gullies. In particular the viscosity of such flows can be estimated to range from a few tens to a few thousands of Pa.s, similar to water triggered debris flows and consistent with previous calculations on Martian gullies. Importantly, these gas fluidized debris flows can occur below the theoretical angle of repose, which has been a concern in the understanding of gully landforms formation. We also performed model calculations for a wide range of latitudes and slope orientations. These simulations reveal that high-pressure CO2 gas trapping in the subsurface and the subsequent formation of ice within the regolith pores are predicted at

  10. Analysis of Orientation-dependence of Martian Gullies

    NASA Technical Reports Server (NTRS)

    Mohan, S.; Bridges, N. T.

    2004-01-01

    The recent discovery of small Martian gullies has stimulated debate about the role that water plays on the Martian surface under current or recent conditions. Of critical importance in evaluating various gully hypotheses is reliable morphometric and orientation data. The former centers on such questions as whether the water (or another fluid) emanated from a surface or sub-surface source and the duration of flow. The latter ties into whether solar insolation has an important effect on formation of the initial water source and subsequent mobilization. Initial studies of gullies indicated a poleward orientation dependence, an observation which has recently been challenged. Herein we investigate the orientation of Martian gullies and the dependence of various parameters on the orientation. Whereas previous studies have been global or through most of the southern hemisphere, we focus on several specific regions. This approach offers some advantages in that regional variations are factored out, such that of lithology, ground water table depth (if any), surface thermal properties, and other parameters are more or less the same in a given region. Differences in gully attributes as a function of orientation within a region can more easily be attributable to solar insolation effects than is the case for global statistics. We use the orientation to constrain several classes of gully formation hypotheses. 1) A favored orientation toward the pole across all regions could indicate a process dominated by melting of cold trapped ice, snow, or condensed volatiles from incident sunlight during summer under current conditions. 2) Variations among all regions would be more consistent with mechanisms less strongly tied to current solar insolation, such as geothermal heating of ice. 3) Favored orientations within specific regions, but differing among regions, could indicate a preference for poleward ices and melting, with orientation being a function of age and dependent on variations

  11. Geometry and significance of stacked gullies on the northern California slope

    USGS Publications Warehouse

    Field, M.E.; Gardner, J.V.; Prior, D.B.

    1999-01-01

    Recent geophysical surveys off northern California reveal patterns of gullies on the sea floor and preserved within continental-slope deposits that represent both erosional and aggradational processes. These surveys, conducted as part of the STRATAFORM project, combined multibeam bathymetry and backscatter with high-resolution seismic profiles. These data provide a new basis for evaluating gully morphology, distribution, and their significance to slope sedimentation and evolution. The continental margin off northern California exhibits an upper slope that has undergone both progradation and aggradation. The slope surface, which dips at <2??to 4.0??, contains a set of straight, evenly spaced, and parallel to sub-parallel gullies that begin at the 380-m isobath and extend onto the Eel and Klamath plateaus and into Trinity Canyon. The surface gullies are typically 100-m wide or more and only 1-2 m deep. The gullied slope is underlain by a sedimentary sequence that contains abundant buried gullies to subsurface depths of over 150 m. Although some of the buried gullies are distinctly erosional, most are part of the aggradational pattern responsible for the overall growth of the slope. The latest phase of gully erosion is marked by a gullied surface lying <20 m below the present-day sea floor. These erosional gullies locally truncate individual reflectors, have small depositional levees, and exhibit greater relief than do overlying gullies exposed on the sea floor. The older subsurface gullies document a period of widespread, but minor, erosion and downslope transport, presumably from a large, proximal sediment source. The cycles of downcutting and gully excavation are a minor part of the stratigraphic section, and are likely related to the combined influence of lower sea levels and higher sediment yields. During aggradation of the slope depositional sequences, sediment was draped over the gully features, producing sediment layers that mimic the underlying gully form

  12. Charles Lyell and 'Modern changes of the Earth': the Milledgeville Gully

    NASA Astrophysics Data System (ADS)

    Kennedy, Barbara A.

    2001-09-01

    One major emphasis of Lyell's Principles of Geology was on the abundance and efficacy of 'present' or 'modern' causes in producing geologic change. He was also determined that the evidence given for the activity of such causes should be scientific and reliable: to that end, he expended tremendous efforts to make his own observations. Perhaps inevitably, he stressed the operation of relatively high magnitude, low frequency events—storms, floods and earthquakes—especially those whose dates of onset were known. A key example of Lyell's interest in the 'modern' was his examination of a 20-year-old gully at Milledgeville, GA, in January 1846. He explicitly related its ultimate cause to the laying bare of the clayey surface horizons as a result of recent forest clearance and its proximate formation to sunbaked cracks in the clay and erosion by rainfall-induced runoff. He also saw this example as merely one of hundreds in the region. Over the 140 years since Lyell's visit, the gully has been repeatedly revisited and even surveyed (by H.A. Ireland in 1937). Its development shows continued growth, followed by increasing stabilisation. This seems to match evidence for the general behaviour of such landforms and the gully, therefore, may serve as a well-documented exemplar for the nature of localised accelerated erosion, regardless of the ultimate initiating factors. Lyell's interest in such short-term erosional features—as indicating the efficacy of modern causes—stands in contrast to his successors' focus on 'geological' scale features such as Niagara Falls.

  13. Fluidized bed steam reformed mineral waste form performance testing to support Hanford Supplemental Low Activity Waste Immobilization Technology Selection

    SciTech Connect

    Jantzen, C. M.; Pierce, E. M.; Bannochie, C. J.; Burket, P. R.; Cozzi, A. D.; Crawford, C. L.; Daniel, W. E.; Fox, K. M.; Herman, C. C.; Miller, D. H.; Missimer, D. M.; Nash, C. A.; Williams, M. F.; Brown, C. F.; Qafoku, N. P.; Neeway, J. J.; Valenta, M. M.; Gill, G. A.; Swanberg, D. J.; Robbins, R. A.; Thompson, L. E.

    2015-10-01

    This report describes the benchscale testing with simulant and radioactive Hanford Tank Blends, mineral product characterization and testing, and monolith testing and characterization. These projects were funded by DOE EM-31 Technology Development & Deployment (TDD) Program Technical Task Plan WP-5.2.1-2010-001 and are entitled “Fluidized Bed Steam Reformer Low-Level Waste Form Qualification”, Inter-Entity Work Order (IEWO) M0SRV00054 with Washington River Protection Solutions (WRPS) entitled “Fluidized Bed Steam Reforming Treatability Studies Using Savannah River Site (SRS) Low Activity Waste and Hanford Low Activity Waste Tank Samples”, and IEWO M0SRV00080, “Fluidized Bed Steam Reforming Waste Form Qualification Testing Using SRS Low Activity Waste and Hanford Low Activity Waste Tank Samples”. This was a multi-organizational program that included Savannah River National Laboratory (SRNL), THOR® Treatment Technologies (TTT), Pacific Northwest National Laboratory (PNNL), Oak Ridge National Laboratory (ORNL), Office of River Protection (ORP), and Washington River Protection Solutions (WRPS). The SRNL testing of the non-radioactive pilot-scale Fluidized Bed Steam Reformer (FBSR) products made by TTT, subsequent SRNL monolith formulation and testing and studies of these products, and SRNL Waste Treatment Plant Secondary Waste (WTP-SW) radioactive campaign were funded by DOE Advanced Remediation Technologies (ART) Phase 2 Project in connection with a Work-For-Others (WFO) between SRNL and TTT.

  14. Agriculture--Agricultural Production 1, Seed Bed. Kit No. 6. Instructor's Manual [and] Student Learning Activity Guide.

    ERIC Educational Resources Information Center

    Sloan, Lee

    An instructor's manual and student activity guide on the seed bed are provided in this set of prevocational education materials which focuses on the vocational area of agriculture. (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational offerings: agriculture, home economics,…

  15. [Relation between neural structures possessing acetylcholinesterase activity and the hemomicrocirculatory bed of the fascia of the rat].

    PubMed

    Vshivtseva, V V; Lesova, L D

    1986-05-01

    By means of Karnovsky--Roots method the nervous apparatus of the hemomicrocirculatory bed has been revealed in the subcutaneous muscle fascia possessing acetylcholinesterase (AChE) activity. Innervational peculiarities in some microvascular branches, bushy pattern of AChE-positive nervous structures have been stated, as well as their uneven distribution along the vessels.

  16. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight.

  17. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest.

    PubMed

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A; De Dios, Yiri E; Gadd, Nichole E; Wood, Scott J; Riascos, Roy; Kofman, Igor S; Bloomberg, Jacob J; Mulavara, Ajitkumar P; Seidler, Rachael D

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  18. Increased Brain Activation for Dual Tasking with 70-Days Head-Down Bed Rest

    PubMed Central

    Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia A.; De Dios, Yiri E.; Gadd, Nichole E.; Wood, Scott J.; Riascos, Roy; Kofman, Igor S.; Bloomberg, Jacob J.; Mulavara, Ajitkumar P.; Seidler, Rachael D.

    2016-01-01

    Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to simulate the effects of microgravity exposure on human physiology, sensorimotor function, and cognition on Earth. Previous studies have reported that concurrent performance of motor and cognitive tasks can be impaired during space missions. Understanding the consequences of HDBR for neural control of dual tasking may possibly provide insight into neural efficiency during spaceflight. In the current study, we evaluated how dual task performance and the underlying brain activation changed as a function of HDBR. Eighteen healthy men participated in this study. They remained continuously in the 6° head-down tilt position for 70 days. Functional MRI for bimanual finger tapping was acquired during both single task and dual task conditions, and repeated at 7 time points pre-, during- and post-HDBR. Another 12 healthy males participated as controls who did not undergo HDBR. A widely distributed network involving the frontal, parietal, cingulate, temporal, and occipital cortices exhibited increased activation for dual tasking and increased activation differences between dual and single task conditions during HDBR relative to pre- or post-HDBR. This HDBR-related brain activation increase for dual tasking implies that more neurocognitive control is needed for dual task execution during HDBR compared to pre- and post-HDBR. We observed a positive correlation between pre-to-post HDBR changes in dual-task cost of reaction time and pre-to-post HDBR change in dual-task cost of brain activation in several cerebral and cerebellar regions. These findings could be predictive of changes in dual task processing during spaceflight. PMID:27601982

  19. Sublethal Effects of ActiveGuard Exposure on Feeding Behavior and Fecundity of the Bed Bug (Hemiptera: Cimicidae).

    PubMed

    Jones, Susan C; Bryant, Joshua L; Sivakoff, Frances S

    2015-05-01

    Sublethal exposure to pesticides can alter insect behavior with potential for population-level consequences. We investigated sublethal effects of ActiveGuard, a permethrin-impregnated fabric, on feeding behavior and fecundity of bed bugs (Cimex lectularius L.) from five populations that ranged from susceptible to highly pyrethroid resistant. After exposure to ActiveGuard fabric or untreated fabric for 1 or 10 min, adult virgin female bed bugs were individually observed when offered a blood meal to determine feeding attempts and weight gain. Because bed bug feeding behavior is tightly coupled with its fecundity, all females were then mated, and the number of eggs laid and egg hatch rate were used as fecundity measures. We observed that pyrethroid-resistant and -susceptible bugs were not significantly different for all feeding and fecundity parameters. Bed bugs exposed to ActiveGuard for 10 min were significantly less likely to attempt to feed or successfully feed, and their average blood meal size was significantly smaller compared with individuals in all other groups. Independent of whether or not feeding occurred, females exposed to ActiveGuard for 10 min were significantly more likely to lay no eggs. Only a single female exposed to ActiveGuard for 10 min laid any eggs. Among the other fabric treatment-exposure time groups, there were no observable differences in egg numbers or hatch rates. Brief exposure of 10 min to ActiveGuard fabric appeared to decrease feeding and fecundity of pyrethroid-resistant and susceptible bed bugs, suggesting the potentially important role of sublethal exposure for the control of this ectoparasitic insect. PMID:26334815

  20. Timing and causes of gully erosion in the riparian zone of the semi-arid tropical Victoria River, Australia: Management implications

    NASA Astrophysics Data System (ADS)

    McCloskey, G. L.; Wasson, R. J.; Boggs, G. S.; Douglas, M.

    2016-08-01

    Gully erosion in the seasonally wet tropics of Australia is a major source of sediment in rivers. Stabilization of gullies to reduce impacts on aquatic ecosystems and water storages is a focus for management. However, the cause of the gully erosion is poorly understood and so a critical context for soil conservation is missing. It is uncertain if they are the result of post-European cattle grazing or are they much older and related to non-human factors. The causes of riparian gully erosion along a reach of the Victoria River in the semi-arid tropics of Australia were investigated using several methods. Gully complexes were described and characterised by two major components: a Flood Drainage Channel (FDC) and upslope of this an Outer Erosion Feature (OEF) characterised by badlands set within an amphitheatre. The OEF is likely to be a major source of sediment that appears to be of recent origin. A review of historical records, combined with Optically Stimulated Luminescence (OSL) dating, showed that the FDCs were well established prior to the introduction of domestic stock. It also showed that the badlands began to develop about 90 years ago; that is, about 40 years after the arrival of domestic stock. In addition, an analysis of aerial photos coupled with an on-ground survey and analysis of fallout radionuclides revealed that erosion processes are still active within the gully complexes. While the FDCs are natural drainage channels, cattle grazing probably triggered the badland formation, with the expansion aided by increased rainfall in the past 40 years. Therefore, the OEFs are of human origin and protection from grazing of the riparian zone should slow badland erosion and reduce sediment input to the river.

  1. The Morphologic Difference between Crater Slopes with and without Gullies on Mars.

    NASA Astrophysics Data System (ADS)

    Conway, S. J.; Mangold, N.; Balme, M. R.; Ansan, V.

    2012-04-01

    Gullies on Mars are km-scale landforms that resemble small fluvial features on Earth. Their discovery [1] challenged the paradigm that over the last ~2 Ga, Mars has been a dry, frozen desert. The gullies are found commonly in the mid-latitudes, have a pole-facing preference [e.g., 2] and are found many kinds of steep slope (valley wall, dunes, etc.). We have chosen to concentrate on gullies found on impact crater interior wall slopes, as this is the most common type [2]. The aim of our study is to determine whether the morphology of crater walls with and without gullies is different. We chose three study areas, two in the southern hemisphere (where gullies are most common), Terra Cimmeria and Noachis Terra and one in the northern hemisphere, Acidalia Planum. All study areas extend over at least 30° of latitude, from ~25° to 55° North or South. We mapped all craters using the catalog of [3] as a basis. We used HRSC elevation data at better than 100 m/pix to extract the slope and curvature of crater walls in the four cardinal directions. We mapped all the gullies on crater walls in the three areas with the aid of HiRISE, MOC, CTX and HRSC images, using polygons to delimit a slope section that contained gullies. Consistent with previous investigations we found gullies concentrated around 40° latitude, with a pole-facing preference. We also found that east-facing gullies were common in both hemispheres. Gullies were most common in Terra Cimmeria and uncommon in Noachis Terra. We found that for a given latitude band and orientation gullies tend to be found on craters with the steepest slopes and the highest curvature. The lack of gullies in Noachis Terra can be explained by the lack of steep, concave slopes in the mid-latitudes of this region. In Terra Cimmeria we found that almost all steep, concave crater slopes hosted gullies, whereas in Acidalia, in the north, only 10-20% of steep concave slopes had gullies. Crater slopes with gullies in the north are steeper

  2. A hydrological analysis of terrestrial and Martian gullies: Implications for liquid water on Mars

    NASA Astrophysics Data System (ADS)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2014-12-01

    Understanding the role and amounts of liquid water involved in Martian gully formation is critical in studies of the Martian hydrosphere and climate. We performed hydrological analyses using the Manning and Darcy-Weisbach equations in order to infer flow velocities and discharge rates from channels at two gully sites in Noachis Terra, Mars. The results of these analyses were compared with analogous hillside gullies in Australia. We found the velocities and discharge rates for the terrestrial gullies to be comparable to velocities and discharge rates of some small Martian gully channels. In contrast, velocity and discharge in some larger Martian gullies were almost an order of magnitude higher, equating with catastrophic flows on Earth. We postulate that the larger gully channels were more likely formed by a number of smaller flows in a similar manner observed in some terrestrial gullies, a scenario that does not require vast amounts of liquid water to be stable under Martian conditions. In addition, we found that post-fluvial channel widening may have acted on the Martian gullies, probably by dry mass wasting, leading to larger channels than were originally carved by liquid water. Future hydrological analyses of Martian gullies will lead to a greater understanding of the relative importance of dry mass wasting compared to liquid water erosion.

  3. A new dry hypothesis for the formation of Martian linear gullies

    USGS Publications Warehouse

    Diniega, Serina; Hansen, Candice J.; McElwaine, Jim N.; Hugenholtz, C.H.; Dundas, Colin M.; McEwen, Alfred S.; Bourke, Mary C.

    2013-01-01

    Long, narrow grooves found on the slopes of martian sand dunes have been cited as evidence of liquid water via the hypothesis that melt-water initiated debris flows eroded channels and deposited lateral levées. However, this theory has several short-comings for explaining the observed morphology and activity of these linear gullies. We present an alternative hypothesis that is consistent with the observed morphology, location, and current activity: that blocks of CO2 ice break from over-steepened cornices as sublimation processes destabilize the surface in the spring, and these blocks move downslope, carving out levéed grooves of relatively uniform width and forming terminal pits. To test this hypothesis, we describe experiments involving water and CO2 blocks on terrestrial dunes and then compare results with the martian features. Furthermore, we present a theoretical model of the initiation of block motion due to sublimation and use this to quantitatively compare the expected behavior of blocks on the Earth and Mars. The model demonstrates that CO2 blocks can be expected to move via our proposed mechanism on the Earth and Mars, and the experiments show that the motion of these blocks will naturally create the main morphological features of linear gullies seen on Mars.

  4. Mars Gully: No Mineral Trace of Liquid Water

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This image of the Centauri-Hellas Montes region was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 2107 UTC (4:07 p.m. EST) on Jan. 9, 2007, near 38.41 degrees south latitude, 96.81 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is slightly wider than 10 kilometers (6.2 miles) at its narrowest point.

    Narrow gullies found on hills and crater walls in many mid-latitude regions of Mars have been interpreted previously as cut by geologically 'recent' running water, meaning water that flowed on Mars long after impact cratering, tectonic forces, volcanism or other processes created the underlying landforms. Some gullies even eroded into sand dunes, which would date their formation at thousands to millions of years ago, or less. In fact, Mars Orbiter Camera (MOC) images showed two of the gullies have bright deposits near their downslope ends - but those deposits were absent in images taken just a few years earlier. The bright deposits must have formed within the period 1999-2004.

    Has there been running water on Mars so recently? To address that question, CRISM and MRO's other instruments observed the bright gully deposits. CRISM's objective was to determine if the bright deposits contained salts left behind from water evaporating into Mars' thin air. The high-resolution imager's (HiRISE's) objective was to determine if the small-scale morphology was consistent with formation by running water.

    This CRISM image of a bright gully deposit was constructed by showing 2.53, 1.50, and 1.08 micrometer light in the red, green, and blue image planes. CRISM can just resolve the deposits (highlighted by arrows in the inset), which are only a few tens of meters (about 150 feet) across. The spectrum of the deposits barely differs from that of the surrounding material, and is just a little brighter. This difference

  5. [Relationships between soil organic carbon and environmental factors in gully watershed of the Loess Plateau].

    PubMed

    Wei, Xiao-Rong; Shao, Ming-An; Gao, Jian-Lun

    2008-10-01

    Understanding the distribution of organic carbon fractions in soils and their relationships with environmental factors are very important for appraising soil organic carbon status and assessing carbon cycling in the Loess Plateau. In this research, through field investigation and laboratory analysis, we studied the relationships between soil organic carbon and environmental factors in a gully watershed of the Loess Plateau. The environmental factors are landforms, land use conditions and soil types. The results showed that total soil organic carbon presented less variance, while high labile organic carbon presented greater variance. The variation coefficients of them are 34% and 43%, respectively, indicating that the variability of organic carbon in soils increased with the increasing of their activities. Total soil organic carbon, labile organic carbon, middle and high labile organic carbon were highly interrelated and presented similar distribution trend with environmental factors. Among different landforms, land uses, and soil types, the highest contents of organic carbon in different fractions were observed in plateau land, forest and farm lands, and black loessial soils, while the lowest contents of them were observed in gully bottom, grass land, and rubified soils, respectively. The relationships between organic carbon and environmental factors indicate that environmental factors not only directly influence the distribution of soil organic carbon, but also indirectly influence them through affecting the relationships among organic carbon fractions. The relationship between total organic carbon and labile organic carbon responses rapidly to environmental factors, while that between middle labile organic carbon and high labile organic carbon responses slowly to environmental factors. PMID:19143389

  6. Assessment of gully-control structures in the Rio Nutria watershed, Zuni reservation, New Mexico

    USGS Publications Warehouse

    Gellis, Allen C.; Cheama, Andres; Laahty, Vanissa; Lalio, Sheldon

    1995-01-01

    During the latter part of the 19th century and the early part of the 20th century, a major cycle of erosion, arroyo cutting, and gullying occurred in the southwestern United States. Since this erosion cycle began, many projects to control erosion, such as the Civilian Conservation Corps projects in the 1930s, were initiated. However, in the Southwestern United States few studies have documented the effect of these structures in reducing erosion or their effect on gully systems. As part of a watershed rehabilitation project on the Zuni Reservation, New Mexico, 47 structures made either of earth or rocks and 23 rock and brush structures were assessed. Sixty percent of the 47 earth or rock structures have breached and relative to dam height, 65 percent of 47 structures are more than 50 percent silted. Of the 23 rock and brush structures, 22 percent have breached or are close to breaching. Reasons for breaching of all structural types may be piping, scour immediately below the structures, large runoff and large drainage area, poor maintenance, headcutting, and active arroyo deepening and widening. In most cases, documentation does not exist on structure design, the specific purpose for a structure, or when these structures were built.

  7. Evidence for Recent Liquid Water on Mars: Gullies

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold, well below freezing all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30 and 70. The highest latitude at which martian gullies have been found is around 70-75 S on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130C or -200F). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls. Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed.

  8. Northern Hemisphere Gullies on Mars: Analysis of Spacecraft Data and Implications for Formation Mechanisms

    NASA Technical Reports Server (NTRS)

    Heldmann, J. L.; Johansson, H.; Carlsson, E.; Mellon, M. T.

    2005-01-01

    The origin of geologically recent gullies on Mars has remained controversial since the discovery of these features by Malin and Edgett in 2000. Numerous models have been proposed which invoke various physical processes as well as various agents of erosion to explain the origin of the Martian gullies. Hypotheses to explain the formation of the gullies invoke shallow liquid water aquifers, deep liquid water aquifers, melting ground ice, snowmelt, dry landslides, and carbon dioxide aquifers. We test the validity of such gully formation mechanisms by analyzing data from the Mars Global Surveyor and Mars Odyssey spacecrafts to uncover trends in the dimensional and physical properties of the gullies and their surrounding terrain. A similar study has previously been completed for gullies located in the southern hemisphere of Mars. The work presented here focuses exclusively on gullies in the northern hemisphere based on the identification of 136 Mars Orbiter Camera (MOC) images containing clear evidence of gully landforms, distributed in the northern mid and high latitudes. These sites have been analyzed in combination with Mars Orbiter Laser Altimeter (MOLA), Thermal Emission Spectrometer (TES), and Gamma Ray Spectrometer (GRS) data to provide quantitative measurements of numerous gully characteristics. Parameters measured include apparent source depth and distribution, vertical and horizontal dimensions, slopes, compass orientations, near-surface ice content, and factors controlling present-day climatic conditions.

  9. Global documentation of gullies with the Mars Reconnaissance Orbiter Context Camera and implications for their formation

    NASA Astrophysics Data System (ADS)

    Harrison, Tanya N.; Osinski, Gordon R.; Tornabene, Livio L.; Jones, Eriita

    2015-05-01

    Hypotheses ranging from fluvial processes and debris flows to CO2 frost-lubricated or entirely dry flows have been proposed for the formation of martian gullies. In order to constrain these potential formation mechanisms, we mapped the global distribution of gullies on Mars using >54,000 images from the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) covering ∼85% of the martian surface at a resolution of ∼6 m/pixel. The results of this mapping effort confirm the results of studies using lower resolution and/or less areally extensive datasets that gullies are confined to the martian mid- to high-latitudes (∼30-80° in both hemispheres). We also find a clear transition in gully orientation with increasing latitude, going from poleward-facing to equator-facing preference. In general, gullies are more developed on poleward-facing walls, and mid-latitude gullies are more developed than those at higher latitudes. Gullies are also found to be strongly correlated with regions of distinct thermophysical properties of sand- to pebble-sized grains, low albedo, and higher thermal inertia. These observations all point to climate, insolation, and thermal properties of the substrate playing key factors in gully formation on Mars, supporting either a melting ground ice or snowpack hypothesis as the source for water involved in gully formation.

  10. Phases of gully erosion in the Lublin Upland and Roztocze region

    NASA Astrophysics Data System (ADS)

    Zgłobicki, Wojciech; Rodzik, Jan; Superson, Jó Zef; Dotterweich, Markus; Schmitt, Anne

    2014-06-01

    Gullies represent one of the most characteristic features of loess relief and an important feature of the cultural landscape of areas used for agriculture. In extensive parts of the Lublin region, the average gully density exceeds 2 km·km-2, and in the vicinity of Kazimierz Dolny (Nałęczów Plateau) and Szczebrzeszyn (Szczebrzeszyn Roztocze), it reaches 10 km·km-2, which is unique on the European scale (Maruszczak 1973). The natural conditions in some loess areas (the western part of the Nałęczów Plateau, the Szczebrzeszyn Roztocze) are exceptionally conducive to the development of gullies. These conditions include primarily the occurrence of thick loess covers, considerable elevation differences and quite frequent torrential rainfall events in morphological escarpment areas. The prevailing view, however, is that these natural determinants were not sufficient to trigger the intensive processes of gully erosion (Maruszczak 1988; Bork 1989; Vanwalleghem et al. 2003). It was the deforesting (broad-leaved and mixed) linked with the development of agricul ture that led to the dynamic development of gullies (Vanwalleghem et al. 2006; Dotterweich 2008). Until recently, studies on historical gully erosion in the Lublin region had been conducted on a small scale. Estimations of the age of the gullies were based on the analysis of changes in population density (level of anthropogenic pressure on the environment) and climate changes (frequency of torrential rains). On that basis, Maruszczak (1973; 1988) and Buraczyński (1991) conclude that most gullies in the loess areas are not older than 1,000 years. Cartographic materials do not provide any information on the age of gullies. Relatively accurate maps are not older than 100 years while older topographical measurements conducted in forested areas with varied relief are not reliable. Only a few sites located within the loess covers have been examined in detail, i.e. by analysing sediments (including 14C dating) within

  11. Aqueous phase adsorption of cephalexin by walnut shell-based activated carbon: A fixed-bed column study

    NASA Astrophysics Data System (ADS)

    Nazari, Ghadir; Abolghasemi, Hossein; Esmaieli, Mohamad; Sadeghi Pouya, Ehsan

    2016-07-01

    The walnut shell was used as a low cost adsorbent to produce activated carbon (AC) for the removal of cephalexin (CFX) from aqueous solution. A fixed-bed column adsorption was carried out using the walnut shell AC. The effect of various parameters like bed height (1.5, 2 and 2.5 cm), flow rate (4.5, 6 and 7.5 mL/min) and initial CFX concentration (50, 100 and 150 mg/L) on the breakthrough characteristics of the adsorption system was investigated at optimum pH 6.5. The highest bed capacity of 211.78 mg/g was obtained using 100 mg/L inlet drug concentration, 2 cm bed height and 4.5 mL/min flow rate. Three kinetic models, namely Adam's-Bohart, Thomas and Yoon-Nelson were applied for analysis of experimental data. The Thomas and Yoon-Nelson models were appropriate for walnut shell AC column design under various conditions. The experimental adsorption capacity values were fitted to the Bangham and intra-particle diffusion models in order to propose adsorption mechanisms. The effect of temperature on the degradation of CFX was also studied.

  12. Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

    PubMed

    Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

    2014-09-01

    Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure.

  13. Use of activated carbon and natural zeolite as support materials, in an anaerobic fluidised bed reactor, for vinasse treatment.

    PubMed

    Fernández, N; Fdz-Polanco, F; Montalvo, S J; Toledano, D

    2001-01-01

    In Cuba, the alcohol distillation process from cane sugar molasses, produces a final waste (vinasse), with an enormous polluting potential and a high sulfate content. Applying the anaerobic technology, most of the biodegradable organic matter can turn into biogas, rich in methane but with concentrations of sulfide above 1%. The present work develops two experiences with anaerobic fluidized bed reactors (AFBR) using both Cuban raw material, activated carbon and natural zeolite, as support media, with the purpose of obtaining high organic matter removal rates and keeping sulfide and ammonium concentrations in the permissible ranges. The reactors were operated during 120 days, achieving an organic loading rate of 10 kg COD/m3 day, with COD removal above 70%, and a methane production of 2 L/d. The activated carbon and natural zeolite used support materials in anaerobic fluidized bed reactors, and showed good results of distillery waste removal. PMID:11575071

  14. Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies.

    PubMed

    Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

    2016-04-01

    The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m(2)/g), high pore volume (1.23 cm(3)/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution.

  15. Modeling moisture diffusivity, activation energy and specific energy consumption of squash seeds in a semi fluidized and fluidized bed drying.

    PubMed

    Chayjan, Reza Amiri; Salari, Kamran; Abedi, Qasem; Sabziparvar, Ali Akbar

    2013-08-01

    This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160 × 10(-9) and 0.551 × 10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783 × 10(6) and 2.303 × 10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system.

  16. Modeling moisture diffusivity, activation energy and specific energy consumption of squash seeds in a semi fluidized and fluidized bed drying.

    PubMed

    Chayjan, Reza Amiri; Salari, Kamran; Abedi, Qasem; Sabziparvar, Ali Akbar

    2013-08-01

    This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160 × 10(-9) and 0.551 × 10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783 × 10(6) and 2.303 × 10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system. PMID:24425968

  17. Three-component competitive adsorption model for fixed-bed and moving-bed granular activated carbon adsorbers. Part I. Model development.

    PubMed

    Schideman, Lance C; Mariñas, Benito J; Snoeyink, Vernon L; Campos, Carlos

    2006-11-01

    Heterogeneous natural organic matter (NOM) present in all natural waters impedes trace organic contaminant adsorption, and predictive modeling of granular activated carbon (GAC) adsorber performance is often compromised by inadequate accounting forthese competitive effects. Thus, a 3-component adsorption model, COMPSORB-GAC, is developed that separately tracks NOM adsorption and its competitive effects as a function of NOM surface loading. In this model, NOM is simplified into two fictive fractions with distinct competitive effects on trace compound adsorption: a smaller, strongly competing fraction that reduces equilibrium capacity and a larger pore-blocking fraction that reduces adsorption kinetics (both external film mass transfer and surface diffusion). COMPSORB-GAC tracks these two NOM fractions, along with the trace compound, and changes adsorption parameters according to the local surface loading of the two NOM fractions. Model parameters are allowed to vary both temporally and spatially to reflect differences in the NOM preloading conditions that occur in GAC columns. This dual-resistance model is based on homogeneous surface diffusion with external film mass-transfer limitations. The governing equations are expressed in a moving-grid finite-difference formulation to accommodate the modeling of spatially varying parameters and moving-bed reactors with counter-current adsorbent flow. A series of short-term adsorption tests with fresh and preloaded GAC is proposed to determine the necessary model input parameters. The accompanying manuscript demonstrates the parameterization procedure and verifies the model with experimental data. PMID:17144314

  18. Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

    NASA Astrophysics Data System (ADS)

    Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

    2016-02-01

    This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium (q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (ΔG 0), enthalpy (ΔH 0) and entropy (ΔS 0) were determined and the positive value of (ΔH) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

  19. Drama Hike: Land of the Hully Gullies.

    ERIC Educational Resources Information Center

    Jordison, Jerry

    2001-01-01

    The drama hike is a walk in the woods, in which children observe nature and engage in an imaginative search for a "lost civilization" or "strange creatures." Instructions cover scouting out the area beforehand, preparing the children, leading the hike, followup activities, suggestions for creative sites, ideas for language and number activities,…

  20. Trickle Down Theories: A Comparison of Gullies in Three Regions on Mars

    NASA Astrophysics Data System (ADS)

    Phillips, E.; Gilmore, M.

    2001-12-01

    Gullies were identified in Mars Orbiting Camera (MOC) images, and have been attributed to flowing water (Malin&Edgett, Science 288). These gullies emanate directly from the ground and are visible in the walls of canyons and craters; thus the gullies are likely to be the result of groundwater. As on Earth, the depths of these gullies are likely controlled by the presence of an impermeable layer. Our goal is to examine the morphology and depth of the gullies to determine the nature of this controlling layer. Images from Hale Crater, Nirgal Vallis and Dao Vallis were compared, all of which contain gullies but are situated in different latitudes in the southern hemisphere and different geologic settings. The morphologies of these gullies were examined, especially the relationship between the alcove and the channel of the gullies to the surrounding rock layers exposed. Depths of the features in the images were calculated using Mars Orbiter Laser Altimetry (MOLA) data. Once the MOLA profiles were identified and graphed, the profiles were mechanically manipulated using Photoshop to overlay the path the satellite would have scanned in the MOC image. If the small-scale features of the MOLA profile as well as the large-scale features could be correlated accurately, the match was considered a success. In the north wall of Nirgal Vallis, the majority of the gullies emanate consistently ~260+/-30 meters below the surface, with one image containing a gully with a depth of 640+/-10 meters. Dao Vallis shows a greater variation in gully depth than Nirgal Vallis, from as deep as 1131+/-63 meters below the surface to as shallow as 67+/-5 meters. Many of the Dao images contain multiple gullies with origins at different depths. Images from Hale Crater contain gullies both on the central peak and on the northern wall; the depths of these are variable and originate from near the surface to depths of 348+/-64 meters. In Nirgal Vallis, gullies that emanate from a consistent depth lie

  1. Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

    2016-06-01

    Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). PMID:26803903

  2. Quantifying gully erosion contribution from morphodynamic analysis of historical aerial photographs in a large catchment SW Spain

    NASA Astrophysics Data System (ADS)

    Hayas, Antonio; Giráldez, Juan V.; Laguna, Ana; Peña, Peña; Vanwalleghem, Tom

    2015-04-01

    Gully erosion is widely recognized as an important erosion process and source of sediment, especially in Mediterranean basins. Recent advances in monitoring techniques, such as ground-based LiDAR, drone-bounded cameras or photoreconstruction, allow quantifying gully erosion rates with unprecedented accuracy. However, many studies only focus on gully growth during a short period. In agricultural areas, farmers frequently erase gullies artificially. Over longer time scales, this results in an important dynamic of gully growth and infilling. Also, given the significant temporal variability of precipitation, land use and the proper gully erosion processes, gully growth is non-linear over time. This study therefore aims at analyzing gully morphodynamics over a long time scale (1957-2011) in a large catchment in order to quantify gully erosion processes and its contribution to overall sediment dynamics. The 20 km2 study area is located in SW Spain. The extension of the gully network was digitized by photographic interpretation based on aerial photographs from 1957, 1981, 1985, 1999, 2002, 2005, 2007, 2009 and 2011. Gully width was measured at representative control points for each of these years. During this period, the dominant land use changed considerably from herbaceous crops to olive orchards. A field campaign was conducted in 2014 to measure current gully width and depth. Total gully volume and uncertainty was determined by Monte Carlo-based simulations of gully cross-sectional area for unmeasured sections. The extension of the gully network both increased and decreased in the study period. Gully density varied between 1.93 km km-2 in 1957, with a minimum of 1.37 km km-2 in 1981 and a maximum of 5.40 km km-2 in 2011. Gully width estimated in selected points from the orthophotos range between 0.9 m and 59.2 m, and showed a good lognormal fit. Field campaigns results in a collection of cross-section measures with gullies widths between 1.87 and 28.5 m and depths from

  3. Participatory community-based gully rehabilitation on the Ethiopian Highlands: the case of Birr watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the last fifty years, sediment concentrations in the Ethiopian highlands have increased two- to three-fold. The current severity of gully erosion is a major cause of increased sediment loads, but gully rehabilitation has proven to be challenging as success rates have been small. This paper descri...

  4. Influence of gully erosion control on amphibian and reptile communities within riparian zones of channelized streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian zones of streams in northern Mississippi have been impacted by agriculture, channelization, channel incision, and gully erosion. Gully erosion is the most severe form of erosion and has resulted in the fragmentation of remnant riparian zones within agricultural watersheds. One widely used c...

  5. Morphological dynamics of gully systems in the subhumid Ethiopian Highlands: The Debre Mawi watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gully expansion in the Ethiopian highlands dissects vital agricultural lands with the eroded materials adversely impacting downstream resources, for example as they accumulate in reservoirs. While gully expansion and rehabilitation have been more extensively researched in the semi-arid region of Eth...

  6. Exploring the relationship between gully erosion and rainfall erosivity

    NASA Astrophysics Data System (ADS)

    Campo, Miguel; Casalí, Javier; Giménez, Rafael

    2016-04-01

    Rainfall erosivity plays and important role in gully erosion. However, there are few studies that explore this relationship. The main purpose of this work is to analyse the link between observed gully erosion rates and rainfall erosivity. However, in order to get a suitable and comparable set of daily rainfall erosivity data, we firstly evaluate the performance of several daily rainfall erosivity models to estimate the daily accumulated RUSLE EI30 index. One 300 ha watershed (El Cantalar) located in Navarre (Spain) was selected to carry out field studies. A meteorological station located 10 km appart from the experimental site provided daily precipitation records since 1930 to 2009 and also 10min records since 1991 to 2009. In this watershed a total of 35 gully headcuts developed in cohesive soil were monitored. Aerial photographic stereo-pairs covering the study area were used for the survey. These were taken in five different years and at different spatial scales each time: 1956 (1: 34,000), 1967 (1:17,500), 1982 (1:13,500), 2003 (1:20,000) and 2006 (1:2000). Manual restitution of photographs was carried out. 1m resolution DEMs were obtained by triangular interpolation (Triangular Irregular Network) and then used to characterize gully headcuts. Moreover, from the aerial photos and the DEMs, ortho-photographs with a final resolution of 0.40 m were created. The geocoding of the scenes had a Root Mean Square error of less than 0.5 m both in planimetry and altimetry. Furthermore, using the DEMs and the ortho-photographs, volumetric headcut retreat rates for each period were calculated as the product of the lineal retreat and a representative section of the headcut. Daily accumulated RUSLE EI30 index was calculated in a conventional way from records of precipitation every 10 minutes for the period 1991-2009; these results were used as reference data. In addition, for the same period, this index was estimated with daily precipitation records through several models

  7. [Activity of oxidation-reduction enzymes in endotheliocytes of the intestinal hemomicrocirculatory bed under normal conditions and in portal hypertension].

    PubMed

    Gaĭvoronskiĭ, I V; Tikhonova, L P; Chepur, S V; Nichiporuk, G I

    1997-01-01

    An original quantitative examination of oxidation-reduction enzymes activity in endotheliocytes of hemomicroclrculatory vessels of jejunum and rectum submucosal base in normal state and in portal hypertension was performed by the authors. Comparative analysis of the activity of the enzymes studied revealed different metabolic processes intensity in these organs, dependent on current hemodynamic conditions. Cytochemical changes in hemomicrocirculatory bed are consistent with structural reorganizations that arise in the wall of vessels studied, consist of several phases and may be used as an assessment criterion for defining the portal hypertension stage.

  8. Bisphenol A removal by a Pseudomonas aeruginosa immobilized on granular activated carbon and operating in a fluidized bed reactor.

    PubMed

    Mita, Luigi; Grumiro, Laura; Rossi, Sergio; Bianco, Carmen; Defez, Roberto; Gallo, Pasquale; Mita, Damiano Gustavo; Diano, Nadia

    2015-06-30

    Serratia rubidiae, Pseudomonas aeruginosa and Escherichia coli K12 have been studied for their ability of Bisphenol A removal from aqueous systems and biofilm formation on activated granule carbon. Mathematical equations for biodegradation process have been elaborated and discussed. P. aeruginosa was found the best strain to be employed in the process of Bisphenol A removal. The yield in BPA removal of a P. aeruginosa biofilm grown on GAC and operating in a fluidized bed reactor has been evaluated. The results confirm the usefulness in using biological activated carbon (BAC process) to remove phenol compounds from aqueous systems.

  9. The cycle of instability: stress release and fissure flow as controls on gully head retreat

    NASA Astrophysics Data System (ADS)

    Collison, A. J. C.

    2001-01-01

    Gully head and wall retreat has commonly been attributed to fluvial scour and head collapse as a result of soil saturation, sapping or piping. The empirical evidence to substantiate these conceptual models is sparse, however, and often contradictory. This paper explores the hydrological and mechanical controls on gully head and wall stability by modelling the hydrology, stability and elastic deformation of a marl gully complex in Granada Province, south-east Spain. The hydrological and slope-stability simulations show that saturated conditions can be reached only where preferential fissure flow channels water from tension cracks into the base of the gully head, and that vertical or subvertical heads will be stable unless saturation is achieved. Owing to the high unsaturated strengths of marl measured in this research, failure in unsaturated conditions is possible only where the gully head wall is significantly undercut. Head retreat thus requires the formation of either a tension crack or an undercut hollow. Finite-element stress analysis of eroding slopes reveals a build up of shear stress at the gully head base, and a second stress anomaly just upslope of the head wall. Although tension cracks on gully heads have often been attributed to slope unloading, this research provides strong evidence that the so called sapping hollow commonly found in the gully headwall base is also a function of stress release. Although further research is needed, it seems possible that pop out failures in river channels may be caused by the same process. The hydrological analysis shows that, once a tension crack has developed, throughflow velocity in the gully headwall will increase by an order of magnitude, promoting piping and enlargement of this weakened area. It is, therefore, possible to envisage a cycle of gully expansion in which erosion, channel incision or human action unloads the slope below a gully head, leading to stress patterns that account for the tension crack and a

  10. Post-fire Gully Rejuvenation - Evidence of Process Thresholds Controlled by Vegetation Disturbance

    NASA Astrophysics Data System (ADS)

    Hyde, K.; Woods, S.

    2011-12-01

    High intensity rainfall may trigger gully rejuvenation on hillslopes recently disturbed by wildfire, leading to debris-laden flows which generally contribute the majority of sediment transported in post-fire erosion events. We investigated the extent to which the occurrence of gully rejuvenation can be predicted based upon burn severity, rainfall data and basin morphometric variables. Field surveys were conducted at six Northern Rockies sites to identify occurrence of gully rejuvenation in first order catchments and to map and characterize the location of gully heads. NEXRAD and rain gage data analysis coupled with field observations characterized rainfall intensity and extent. Building on previous work we quantified burn severity using the Vegetation Disturbance Index (VDI), a continuous metric based upon Burned Area Reflectance Classification (BARC) maps derived from satellite imagery using the dNBR algorithm. GIS analysis combined the VDI with morphometric factors expected to influence hillslope stability. Gully heads marked abrupt transition in channel form. Above gully heads, channels were shallow and U-shaped with gentle transition to the hillslope and fine root hairs intact. Angular edges marked deep gully head incisions which down-cut channel floors from 0.2-0.3 to 1.0 meter or more. Any remaining roots were coarse and the hillslope transition was sharp. Gully heads were located at variable distances below the master rill head of the catchment hollow. Distances were obviously greater where live canopy remained upslope. Gully head morphology strongly suggests flow force transition and exceedance of an erosion process threshold. The variable distance of the gully head below the hollow suggest upslope controls influencing initiation point, possibly degree and spatial pattern of burn severity. Binary logistic regression revealed stronger correlation between gully rejuvenation and VDI than morphometric variables. The statistical strength using the continuous

  11. Gully measurement strategies in a pixel using python

    NASA Astrophysics Data System (ADS)

    Wells, Robert; Momm, Henrique; Bennett, Sean; Dabney, Seth

    2015-04-01

    Gullies are often the single largest sediment sources within the landscape; however, measurement and process description of these channels presents challenges that have limited complete understanding. A strategy currently being employed in the field and laboratory to measure topography of gullies utilizes inexpensive, off-the-shelf cameras and software. Photogrammetry may be entering an enlightened period, as users have numerous choices (cameras, lenses, and software) and many are utilizing the technology to define their surroundings; however, the key for those seeking answers will be what happens once topography is represented as a three-dimensional digital surface model. Perhaps the model can be compared with another model to visualize change, either in topography or in vegetation cover, or both. With these models of our landscape, prediction technology should be rejuvenated and/or reinvented. Over the past several decades, researchers have endeavored to capture the erosion process and transfer these observations through oral and written word. Several have hypothesized a fundamental system for gully expression in the landscape; however, this understanding has not transferred well into our prediction technology. Unlike many materials, soils often times do not behave in a predictable fashion. Which soil physical properties lend themselves to erosion process description? In most cases, several disciplines are required to visualize the erosion process and its impact on our landscape. With a small camera, the landscape becomes more accessible and this accessibility will lead to a deeper understanding and development of uncompromised erosion theory. Why? Conservation of our soil resources is inherently linked to a complete understanding of soil wasting.

  12. Using Wind Driven Tumbleweed Rovers to Explore Martian Gully Features

    NASA Technical Reports Server (NTRS)

    Antol, Jeffrey; Woodard, Stanley E.; Hajos, Gregory A.; Heldmann, Jennifer L.; Taylor, Bryant D.

    2004-01-01

    Gully features have been observed on the slopes of numerous Martian crater walls, valleys, pits, and graben. Several mechanisms for gully formation have been proposed, including: liquid water aquifers (shallow and deep), melting ground ice, snow melt, CO2 aquifers, and dry debris flow. Remote sensing observations indicate that the most likely erosional agent is liquid water. Debate concerns the source of this water. Observations favor a liquid water aquifer as the primary candidate. The current strategy in the search for life on Mars is to "follow the water." A new vehicle known as a Tumbleweed rover may be able to conduct in-situ investigations in the gullies, which are currently inaccessible by conventional rovers. Deriving mobility through use of the surface winds on Mars, Tumbleweed rovers would be lightweight and relatively inexpensive thus allowing multiple rovers to be deployed in a single mission to survey areas for future exploration. NASA Langley Research Center (LaRC) is developing deployable structure Tumbleweed concepts. An extremely lightweight measurement acquisition system and sensors are proposed for the Tumbleweed rover that greatly increases the number of measurements performed while having negligible mass increase. The key to this method is the use of magnetic field response sensors designed as passive inductor-capacitor circuits that produce magnetic field responses whose attributes correspond to values of physical properties for which the sensors measure. The sensors do not need a physical connection to a power source or to data acquisition equipment resulting in additional weight reduction. Many of the sensors and interrogating antennae can be directly placed on the Tumbleweed using film deposition methods such as photolithography thus providing further weight reduction. Concepts are presented herein for methods to measure subsurface water, subsurface metals, planetary winds and environmental gases.

  13. Using Wind Driven Tumbleweed Rovers to Explore Martian Gully Features

    NASA Technical Reports Server (NTRS)

    Antol, Jeffrey; Woodard, Stanley E.; Hajos, Gregory A.; Heldmann, Jennifer L.; Taylor, Bryant D.

    2005-01-01

    Gully features have been observed on the slopes of numerous Martian crater walls, valleys, pits, and graben. Several mechanisms for gully formation have been proposed, including: liquid water aquifers (shallow and deep), melting ground ice, snow melt, CO2 aquifers, and dry debris flow. Remote sensing observations indicate that the most likely erosional agent is liquid water. Debate concerns the source of this water. Observations favor a liquid water aquifer as the primary candidate. The current strategy in the search for life on Mars is to "follow the water." A new vehicle known as a Tumbleweed rover may be able to conduct in-situ investigations in the gullies, which are currently inaccessible by conventional rovers. Deriving mobility through use of the surface winds on Mars, Tumbleweed rovers would be lightweight and relatively inexpensive thus allowing multiple rovers to be deployed in a single mission to survey areas for future exploration. NASA Langley Research Center (LaRC) is developing deployable structure Tumbleweed concepts. An extremely lightweight measurement acquisition system and sensors are proposed for the Tumbleweed rover that greatly increases the number of measurements performed while having negligible mass increase. The key to this method is the use of magnetic field response sensors designed as passive inductor-capacitor circuits that produce magnetic field responses whose attributes correspond to values of physical properties for which the sensors measure. The sensors do not need a physical connection to a power source or to data acquisition equipment resulting in additional weight reduction. Many of the sensors and interrogating antennae can be directly placed on the Tumbleweed using film deposition methods such as photolithography thus providing further weight reduction. Concepts are presented herein for methods to measure subsurface water, subsurface metals, planetary winds and environmental gases.

  14. Bed bugs.

    PubMed

    Foulke, Galen T; Anderson, Bryan E

    2014-09-01

    The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem. PMID:25577850

  15. Re-analysis of martian gully orientation and slope for comparison with climate model predictions of freeze-thaw and dry-ice sublimation.

    NASA Astrophysics Data System (ADS)

    Conway, Susan; Harrison, Tanya; Lewis, Stephen; Balme, Matthew; Soare, Richard; Britton, Andrew

    2016-04-01

    hours during which the surface temperature was below the CO2 condensation point of 149K. We use these data as a proxy for where CO2sublimation processes can be active. (ii) The number of sols for which the daily minimum is below 273K and the daily maximum is above 273K. We use these data as a proxy for where ice could be stable and then melt during freeze-thaw cycles. Our results reveal that neither of these simple modelling cases exactly fits the observational data, therefore we conclude that it is likely that a mixture of CO2 and water related processes are responsible for forming martian gullies. We aim to perform a number of tests to assess both the applicability of these simple proxies and to test a wider range of substrate properties (buried ice) and orbital parameters (perihelion and increased atmospheric pressure at high obliquity) to see if they give better fits to our observations.

  16. Re-analysis of martian gully orientation and slope for comparison with climate model predictions of freeze-thaw and dry-ice sublimation.

    NASA Astrophysics Data System (ADS)

    Conway, Susan; Harrison, Tanya; Lewis, Stephen; Balme, Matthew; Soare, Richard; Britton, Andrew

    2016-04-01

    during which the surface temperature was below the CO2 condensation point of 149K. We use these data as a proxy for where CO2sublimation processes can be active. (ii) The number of sols for which the daily minimum is below 273K and the daily maximum is above 273K. We use these data as a proxy for where ice could be stable and then melt during freeze-thaw cycles. Our results reveal that neither of these simple modelling cases exactly fits the observational data, therefore we conclude that it is likely that a mixture of CO2 and water related processes are responsible for forming martian gullies. We aim to perform a number of tests to assess both the applicability of these simple proxies and to test a wider range of substrate properties (buried ice) and orbital parameters (perihelion and increased atmospheric pressure at high obliquity) to see if they give better fits to our observations.

  17. Groundwater discharge and gully formation on martian slopes

    NASA Astrophysics Data System (ADS)

    Goldspiel, Jules M.; Squyres, Steven W.

    2011-01-01

    Young gullies and gully deposits on walls of martian craters have been cited as evidence that liquid water flowed on the surface of Mars relatively recently. Effects of variable environmental conditions at the surface of Mars are modeled and applied to the case of groundwater emergence from shallow aquifers to investigate whether groundwater is a viable source to enable the erosion of these gullies. The model includes detailed treatment of ice growth in the aquifer. Model results indicate that groundwater discharge can be maintained under the current environmental conditions if the aquifer permeability is like that of terrestrial gravel or higher, if the aquifer is 350 K or warmer, or if the aquifer is a brine with a freezing point depressed to 250 K or below. Groundwater discharge cannot be maintained for the conservative case of a cold, pure water, semi-pervious aquifer. Cold (275 K) pure water pervious (gravel) aquifers, warm (350 K) pure water semi-pervious aquifers, and cold (275 K) CaCl 2 brine semi-pervious aquifers all exhibit a dependence of discharge on season, latitude and slope orientation in our modeling. Seasonal, latitudinal and azimuthal discharge variations are strongest for cold CaCl 2 brine semi-pervious aquifers, with discharges from this aquifer type favoring equator-facing slopes at mid and high southern latitudes. At all latitudes and slope azimuths under our nominal conditions, the cold pure water pervious aquifer, the cold pure water semi-pervious aquifer and the cold CaCl 2 brine semi-pervious aquifer all freeze completely shortly after the simulations are started. Discharge restarts in the summer for the cold pure water pervious aquifer and the cold brine aquifer, but discharge does not restart for the cold pure water semi-pervious aquifer. The warm pure water semi-pervious aquifer maintains daily seeps throughout the year at all but high latitudes. In the case of the cold pure water pervious aquifer, approximately 500,000 m 3 of water

  18. Bed rest in pregnancy.

    PubMed

    Bigelow, Catherine; Stone, Joanne

    2011-01-01

    The use of bed rest in medicine dates back to Hippocrates, who first recommended bed rest as a restorative measure for pain. With the formalization of prenatal care in the early 1900s, maternal bed rest became a standard of care, especially toward the end of pregnancy. Antepartum bed rest is a common obstetric management tool, with up to 95% of obstetricians utilizing maternal activity restriction in some way in their practice. Bed rest is prescribed for a variety of complications of pregnancy, from threatened abortion and multiple gestations to preeclampsia and preterm labor. Although the use of bed rest is pervasive, there is a paucity of data to support its use. Additionally, many well-documented adverse physical, psychological, familial, societal, and financial effects have been discussed in the literature. There have been no complications of pregnancy for which the literature consistently demonstrates a benefit to antepartum bed rest. Given the well-documented adverse effects of bed rest, disruption of social relationships, and financial implications of this intervention, there is a real need for scientific investigation to establish whether this is an appropriate therapeutic modality. Well-designed randomized, controlled trials of bed rest versus normal activity for various complications of pregnancy are required to lay this debate to rest once and for all. PMID:21425272

  19. Double-bed-type extraction needle packed with activated-carbon-based sorbents for very volatile organic compounds.

    PubMed

    Ueta, Ikuo; Samsudin, Emi Liana; Mizuguchi, Ayako; Takeuchi, Hayato; Shinki, Takumi; Kawakubo, Susumu; Saito, Yoshihiro

    2014-01-01

    A novel needle-type sample preparation device was developed for the determination of very volatile organic compounds (VVOCs) in gaseous samples by gas chromatography-mass spectrometry (GC-MS). Two types of activated-carbon-based sorbents, Carbopack X and a carbon molecular sieve (CMS), were investigated as the extraction medium. A double-bed-type extraction needle showed successful extraction and desorption performance for all investigated VVOCs, including acetaldehyde, isoprene, pentane, acetone, and ethanol. Sensitive and reliable determination of VVOCs was achieved by systematically optimizing several desorption conditions. In addition, the effects of sample humidity on the extraction and desorption of analytes were investigated with the needle-type extraction devices. Only the CMS packed extraction needle was adversely affected by sample humidity during the desorption process; on the other hand the double-bed-type extraction needle was unaffected by sample humidity. Finally, the developed double-bed-type extraction needle was successfully applied to the analysis of breath VVOCs of healthy subjects. PMID:24176747

  20. Debris flows of the mountain massif of Hjorthfjellet and Adventtoppen, Svalbard: Implications for gullies on mountains in the Argyre basin, Mars

    NASA Astrophysics Data System (ADS)

    Reiss, D.; Hiesinger, H.; Zanetti, M.; Hauber, E.; Johnsson, A.; Carlsson, E.; Raack, J.; Olvmo, M.; Johansson, H. A. B.; Johansson, L.; Fredriksson, S.; Schmidt, H. T.; McDaniel, S.; Heldmann, J. L.; McKay, C. P.

    2008-09-01

    will focus on the regional distribution of gullies on the Hjorthfjellet and Adventtoppen mountain massif (Fig. 1, inset and Fig. 2), and detailed local studies of individual gullies on the same mountain massif are carried out as described by [8] and [9]. The Hjorthfjellet and Adventtoppen mountain massif consists of four stratigraphic units of sandstone and shales from the Tertiary and Mesozoic [10]. Several studies concerning talus slopes and debris flows on Svalbard have been performed in the last decades [e.g., 11, 12, 13, 14]. Regional studies of [14] using airborne imagery revealed that there are differences in the frequency and activity of debris flows on Svalbard between east- and west-facing slopes. Åkerman [14] suggested that differences in the solar radiation, the depth of the active layer and the amount of precipitation cause variances in the morphology and morphometry of the debris slopes as well as variances in the frequency and age of debris flows between east- and west-facing slopes. Studies and direct observations imply that debris flows on Svalbard are triggered by high intensity rainfall [e.g., 14, 15]. Gullies on mountains in Argyre basin, Mars For a comparative study on Mars we chose the Argyre region. Several isolated mountain massifs occur in the Nereidum and Charitum Montes (Fig. 3) with similar morphologies as the studied massif in Svalbard. A first data analysis with High Resolution Stereo Camera (HRSC) data revealed that gullies occur on the mountain slopes only at specific orientations. Fig. 4 shows an example of an isolated mountain, on which gullies only occur on west-facing slopes. Project Description The formation of gullies on Earth depends on several parameters, including rainfall and/or melting of snow, the presence of steep slopes, and sufficient amounts of fines/debris [e.g., 16]. As on Earth, the differences of slope angles and variabilities in bedrock and grain sizes influence the regional occurrence of gullies [17]. The main

  1. Effect of three day bed-rest on circulatory and hormonal responses to active orthostatic test in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Kubala, P.; Smorawinski, J.; Kaciuba-Uscilko, H.; Nazar, K.; Bicz, B.; Greenleaf, J. E.

    1996-01-01

    Circulatory and hormonal parameters were measured in endurance-trained athletes and control subjects during orthostatic tolerance tests conducted prior to and after three days of bed rest. Heart rate and blood pressure changes due to bed rest appeared to be the same in both groups. Hormonal changes, however, were different between the two groups, with the athletes having decreased sympathoadrenal activity and increased plasma renin activity. Untrained subjects had changes in cortisol secretion only.

  2. Recent bright gully deposits on Mars: Wet or dry flow?

    USGS Publications Warehouse

    Pelletier, J.D.; Kolb, K.J.; McEwen, A.S.; Kirk, R.L.

    2008-01-01

    Bright gully sediments attributed to liquid water flow have been deposited on Mars within the past several years. To test the liquid water flow hypothesis, we constructed a high-resolution (1 m/pixel) photogrammetric digital elevation model of a crater in the Centauri Montes region, where a bright gully deposit formed between 2001 and 2005. We conducted one-dimensional (1-D) and 2-D numerical flow modeling to test whether the deposit morphology is most consistent with liquid water or dry granular How. Liquid water flow models that incorporate freezing can match the runout distance of the flow for certain freezing rates but fail to reconstruct the distributary lobe morphology of the distal end of the deposit. Dry granular flow models can match both the observed runout distance and the distal morphology. Wet debris flows with high sediment concentrations are also consistent with the observed morphology because their rheologies are often similar to that of dry granular flows. As such, the presence of liquid water in this flow event cannot be ruled out, but the available evidence is consistent with dry landsliding. ?? 2008 The Geological Society of America.

  3. Spatial diversity of gully density of the Lublin Upland and Roztocze Hills (SE Poland)

    NASA Astrophysics Data System (ADS)

    Gawrysiak, Leszek; Harasimiuk, Marian

    2012-01-01

    Compared to other regions in Poland, the Lublin Upland and Roztocze Hills are distinguished by the density and size of gully systems. In this area, morphometric analyses using GIS tools were performed based on digital data processed from 1:10 000 topographic maps and the Digital terrain Model. The results obtained allowed distinguishing of 17 "gully regions", i.e. areas characterized by a high concentration of gully forms. The analysis of distribution of gullies in relation to other environmental elements demonstrated that the particularly intensive development of gullies in specific areas was associated with geomorphological, geological, hydrogeological, and paleogeographical factors. The anthropogenic impact, i.e. intensive, long-term agricultural management and consequent deforestation, was of great importance as well. The gully regions identified are characterized by a varied surface area and dissection density that in extreme cases reaches over 10 km/km2. From the economic point of view, the phenomenon is unfavourable, as it leads to fragmentation of arable land and intensification of erosion processes. On the other hand, gully regions offer attractive landscape and natural values, therefore some areas have been included in various protection programmes.

  4. Gully evolution in field crops on vertic soils under conventional agriculture

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Pérez, Rafael; Mora, Jose; Gómez, Jose A.

    2015-04-01

    Gully erosion is a major process contributing to soil degradation on cultivated areas. Its effects are especially intense in farms under conventional agriculture characterised by the use of heavy machinery for land levelling and herbicides leading to the depletion of natural vegetation in valley locations. When the soil (e.g. vertic soils) and parent material conditions (e.g. soft erodible marls) are favourable to incision, gully features may present large dimensions, producing the loss of significant proportions of productive land. This study evaluates the evolution of several gully networks located in Córdoba (Spain) within the Campiña area (a rolling landscape on Miocene marls) with conventional agriculture and gully filling operations as the predominant farm practices. The area of the catchments ranged from 10 to 100 ha, they were covered by field crops (mostly bean, sunflower and wheat) on vertic soils. Firstly, we carried out a historical analysis of the gully development during the last six decades by aerial image interpretation. Secondly, a number of field surveys were conducted to characterise the evolution of the gully morphology in a period of five years (2010-2014). For this purpose, a range of measurement techniques were used: pole and tape, differential GPS and 3D photo-reconstruction. Finally, the influence of topography (slope and drainage area) on gully dimensions along the longitudinal profile was assessed.

  5. A novel topographic parameterization scheme indicates that martian gullies display the signature of liquid water

    NASA Astrophysics Data System (ADS)

    Conway, Susan J.; Balme, Matthew R.

    2016-11-01

    Martian gullies resemble gullies carved by water on Earth, yet are thought to have formed in an extremely cold (< - 50°C) and dry (humidity <100 precipitable micrometers) surface environment (cf. Mellon et al., 2004). Despite more than a decade of observations, no consensus has emerged as to whether liquid water is required to form martian gullies, with some recent studies favouring dry CO2-driven processes. That this argument persists demonstrates the limitations of morphological interpretations made from 2D images, especially when similar-looking landforms can form by very different processes. To overcome this we have devised a parameterization scheme, based on statistical discriminant analysis and hydrological terrain analysis of meter-scale digital topography data, which can distinguish between dry and wet surface processes acting on a landscape. Applying this approach to new meter-scale topographic datasets of Earth, the Moon and Mars, we demonstrate that martian gullied slopes are dissimilar to dry, gullied slopes on Earth and the Moon, but are similar to both terrestrial debris flows and fluvial gullies. We conclude that liquid water was integral to the process by which martian gullies formed. Finally, our work shows that quantitative 3D analyses of landscape have great potential as a tool in planetary science, enabling remote assessment of processes acting on planetary surfaces.

  6. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations.

  7. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations. PMID:24729067

  8. Modelling study of three-dimensional circulation and particle movement over the Sable Gully of Nova Scotia

    NASA Astrophysics Data System (ADS)

    Shan, Shiliang; Sheng, Jinyu; Greenan, Blair John William

    2014-01-01

    The Sable Gully is a broad deep underwater canyon located to the east of Sable Island on the edge of the Scotian Shelf. Being the home of many marine species including the endangered Northern Bottlenose Whale, the Gully was designated as a marine protected area (MPA) in 2004. Better understanding of physical environmental conditions over this MPA is needed for sustainable ecosystem management. In this study, a multi-nested ocean circulation model and a particle tracking model are used to examine the three-dimensional (3D) circulation and movement of particles carried passively by the flow over the Sable Gully. The 3D circulation model is driven by tides, wind, and surface heat/freshwater fluxes. The model performance is assessed by comparing the results with the previous numerical tidal results and current meter observations made in the Gully. The simulated tidal circulation over the Gully and adjacent waters is relatively strong on shallow banks and relatively weak on the continental slope. Below the depth of the Gully rim ( ˜ 200 m), the tidal currents are constrained by the thalweg of the Gully and amplified toward the Gully head. The simulated subtidal circulation in the Gully has a complex spatial structure and significant seasonal variability. The simulated time-dependent 3D flow fields are then used in a particle tracking model to study the particle movements, downstream and upstream areas, and residence time of the Gully. Based on the movements of particles released at the depth of the Gully rim and tracked forward in time, the e-folding residence time is estimated to be about 7 and 13 days in February and August 2006, respectively. The Gully flanks are identified as high retention areas with the typical residence time of 10 and 20 days in February and August 2006, respectively. Tracking particles with and without tides reveals that tidal circulation reduces the value of residence time in the Gully, particularly along the Gully flanks.

  9. Estimating gully erosion contribution to large catchment sediment yield rate in Tanzania

    NASA Astrophysics Data System (ADS)

    Ndomba, Preksedis Marco; Mtalo, Felix; Killingtveit, Aanund

    The objective of this paper is to report on the issues and proposed approaches in estimating the contribution of gully erosion to sediment yield at large catchment. The case study is the upstream of Pangani River Basin (PRB) located in the North Eastern part of Tanzania. Little has been done by other researchers to study and/or extrapolate gully erosion results from plot or field scale to large catchment. In this study multi-temporal aerial photos at selected sampling sites were used to estimate gully size and morphology changes over time. The laboratory aerial photo interpretation results were groundtruthed. A data mining tool, Cubist, was used to develop predictive gully density stepwise regression models using aerial photos and environment variables. The delivery ratio was applied to estimate the sediment yield rate. The spatial variations of gully density were mapped under Arc View GIS Environment. Gully erosion sediment yield contribution was estimated as a ratio between gully erosion sediment yield and total sediment yield at the catchment outlet. The general observation is that gullies are localized features and not continuous spatially and mostly located on some mountains’ foot slopes. The estimated sediment yield rate from gullies erosion is 6800 t/year, which is about 1.6% of the long-term total catchment sediment yield rate. The result is comparable to other study findings in the same catchment. In order to improve the result larger scale aerial photos and high resolution spatial data on soil-textural class and saturated hydraulic conductivity - are recommended.

  10. Predicting the susceptibility to gully initiation in data-poor regions

    NASA Astrophysics Data System (ADS)

    Dewitte, Olivier; Daoudi, Mohamed; Bosco, Claudio; Van Den Eeckhaut, Miet

    2015-01-01

    Permanent gullies are common features in many landscapes and quite often they represent the dominant soil erosion process. Once a gully has initiated, field evidence shows that gully channel formation and headcut migration rapidly occur. In order to prevent the undesired effects of gullying, there is a need to predict the places where new gullies might initiate. From detailed field measurements, studies have demonstrated strong inverse relationships between slope gradient of the soil surface (S) and drainage area (A) at the point of channel initiation across catchments in different climatic and morphological environments. Such slope-area thresholds (S-A) can be used to predict locations in the landscape where gullies might initiate. However, acquiring S-A requires detailed field investigations and accurate high resolution digital elevation data, which are usually difficult to acquire. To circumvent this issue, we propose a two-step method that uses published S-A thresholds and a logistic regression analysis (LR). S-A thresholds from the literature are used as proxies of field measurement. The method is calibrated and validated on a watershed, close to the town of Algiers, northern Algeria, where gully erosion affects most of the slopes. The gullies extend up to several kilometres in length and cover 16% of the study area. First we reconstruct the initiation areas of the existing gullies by applying S-A thresholds for similar environments. Then, using the initiation area map as the dependent variable with combinations of topographic and lithological predictor variables, we calibrate several LR models. It provides relevant results in terms of statistical reliability, prediction performance, and geomorphological significance. This method using S-A thresholds with data-driven assessment methods like LR proves to be efficient when applied to common spatial data and establishes a methodology that will allow similar studies to be undertaken elsewhere.

  11. Tapered bed bioreactor

    DOEpatents

    Scott, Charles D.; Hancher, Charles W.

    1977-01-01

    A vertically oriented conically shaped column is used as a fluidized bed bioreactor wherein biologically catalyzed reactions are conducted in a continuous manner. The column utilizes a packing material a support having attached thereto a biologically active catalytic material.

  12. Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors.

    PubMed

    Choi, Young Chul; Li, Xu; Raskin, Lutgarde; Morgenroth, Eberhard

    2008-07-01

    Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions.

  13. Supercritical CO2 desorption of activated carbon loaded with 2,2,3,3-tetrafluoro-1-propanol in a rotating packed bed.

    PubMed

    Tan, Chung-Sung; Lee, Pei-Lun

    2008-03-15

    Desorption of activated carbon loaded with 2,2,3,3-tetrafluoro-1-propanol (TFP) by supercritical carbon dioxide in a rotating packed bed was investigated in this study. The experimental data show that the time required to achieve complete desorption of TFP from activated carbon in a rotating packed bed was much lower than that in a static packed bed. The reduction of desorption time is attributed to the presence of centrifugal force. The supercritical CO2 desorption efficiency in a rotating packed bed was observed to increase with increasing rotation speed, pressure, and C02 flow rate. To enhance desorption efficiency, a smaller activated carbon particle size was suggested. At low operating pressures such as 8.96 and 11.72 MPa, a better desorption efficiency was found to occur at lower temperatures in a temperature range of 305-335 K. However, at high operating pressures such as 15.86 MPa, a temperature of 315 K was found to be more appropriate for desorption, as compared to other temperatures. Due to a reduction of packed bed volume and an increase in desorption efficiency, supercritical CO2 desorption in a rotating packed bed is suggested for recovering TFP from the exhaust gases. PMID:18409651

  14. Nanoporous activated carbon fluidized bed catalytic oxidations of aqueous o, p and m-cresols: kinetic and thermodynamic studies.

    PubMed

    Karthikeyan, S; Sekaran, G; Gupta, V K

    2013-07-01

    Nanoporous activated carbon prepared from rice husk through precarbonisation at 400 °C and phosphoric acid activation at 800 °C was used as fluidized bed in Fenton oxidation of the o, p and m-cresols in aqueous solution. The efficiencies of homogeneous Fenton oxidation, fluidized Fenton oxidation and aerobic biological oxidation systems for the removal of o, p and m-cresols in aqueous solution have been compared. The kinetic constants and the thermodynamic parameters for the homogeneous Fenton, heterogeneous Fenton and aerobic biological oxidations of o, p and m-cresols in synthetic wastewater were determined. The degradation of cresols in synthetic wastewater was confirmed using FT-IR, (1)H-NMR and UV-visible spectroscopy. PMID:23292221

  15. Microbial community distribution and extracellular enzyme activities in leach bed reactor treating food waste: effect of different leachate recirculation practices.

    PubMed

    Xu, Su Yun; Karthikeyan, Obuli P; Selvam, Ammaiyappan; Wong, Jonathan W C

    2014-09-01

    This study aimed at understanding the relationship between microbial community and extracellular enzyme activities of leach bed reactor (LBR) treating food waste under different leachate recirculation practices (once per day and continuous) and liquid to solid (L/S) ratios (1:1 and 0.5:1). Microbial community analysis using PCR-DGGE revealed that Lactobacillus sp., Bifidobacter sp., and Proteobacteria were the most abundant species. Number of phylotypes was higher in LBRs with intermittent recirculation; whereas, lower number of phylotypes dominated by the key players of degradation was observed with continuous recirculation. The L/S ratio of 1:1 significantly enhanced the volatile solids removal compared with 0.5:1; however, this effect was insignificant under once a day leachate recirculation. Continuous leachate recirculation with 1:1 L/S ratio significantly improved the organic leaching (240 g COD/kgvolatile solid) and showed distinct extracellular enzyme activities suitable for food waste acidogenesis.

  16. The healing of disturbed hillslopes by gully gravure

    USGS Publications Warehouse

    Osterkamp, W.R.; Toy, T.J.

    1994-01-01

    Results of accelerated erosion on certain constructed surfaces in southeastern Arizona appear similar to those described by Bryan as gully gravure. Twenty cross-section excavations in eight rills inclised into silt-rich lacustrine and fluvial deposits reveal partial filling of the rills by debris derived from overyling fluvial sand, gravel, and cobbles. Interstices of the coarse material gradually fill with fine-grained erosion products, decreasing permeability of the fill and deflecting subsequent runoff to the margins of the fill. Rills and rill fillings thus increase in width with time, and complete veneering of the surface by coarse debris ultimately may occur. Through incision, filling, lateral planation, and armoring, channels of the dissected surface heal and the new hillslope approaches an equilibrium condition. Natural hillslopes in the area with similar geologic conditions have inclinations of 16??-22??, have generally unbroken veneers of coarse debris, and appear subject to the same erosional processes identified at constructed hillslopes. -from Authors

  17. Recent gullies on Mars and the source of liquid water

    NASA Astrophysics Data System (ADS)

    Mellon, Michael T.; Phillips, Roger J.

    2001-10-01

    Geologic features resembling terrestrial water-carved gullies imply that liquid water has flowed recently on the surface of Mars and challenge our views of the present-day low-temperature environment. We evaluate two possible mechanisms for the formation of liquid water under environmental conditions that we expect to have existed on Mars in its recent past. First, we examine the stability of ground ice in the permafrost and the potential for melting near-surface ground ice (in the top few meters of soil) by solar heating and subsurface conduction. Second, we examine the potential for melting and refreezing of ice at shallow depths due to geothermal heating. We find that near-surface ground ice does not reach the melting point of water under a range of conditions of soil thermophysical properties, latitudes, obliquities, and surface slopes. The atmosphere remains too dry for the ground ice to melt, even at high obliquity; instead, ice sublimates before reaching melting temperatures. However, the presence of salts in concentrations of 15-40% can adequately lower the melting point to allow melting to occur. We also find that a combination of a global average geothermal heat flux and a thick, low-conductivity, unconsolidated regolith raises the depth of the melting isotherm to less than a few hundred meters from the surface. Orbitally induced oscillations in the mean annual surface temperature can cause freezing cycles in a confined aquifer at this depth. Freezing pressures generated are adequate to fracture ice-cemented ground and allow water to escape to the surface, similar to the formation and evolution of terrestrial pingos in shallow permafrost. Both mechanisms are possible; however, the geothermal mechanism is consistent with the observations of the distribution of gullies, while the salty near-surface ground ice mechanism is not. Further observational tests that can be performed with existing and future spacecraft are suggested.

  18. Erosion research with a digital camera: the structure from motion method used in gully monitoring - field experiments from southern Morocco

    NASA Astrophysics Data System (ADS)

    Kaiser, Andreas; Rock, Gilles; Neugirg, Fabian; Müller, Christoph; Ries, Johannes

    2014-05-01

    From a geoscientific view arid or semiarid landscapes are often associated with soil degrading erosion processes and thus active geomorphology. In this regard gully incision represents one of the most important influences on surface dynamics. Established approaches to monitor and quantify soil loss require costly and labor-intensive measuring methods: terrestrial or airborne LiDAR scans to create digital elevation models and unmanned airborne vehicles for image acquisition provide adequate tools for geomorphological surveying. Despite their ever advancing abilities, they are finite with their applicability in detailed recordings of complex surfaces. Especially undercuttings and plunge pools in the headcut area of gully systems are invisible or cause shadowing effects. The presented work aims to apply and advance an adequate tool to avoid the above mentioned obstacles and weaknesses of the established methods. The emerging structure from motion-based high resolution 3D-visualisation not only proved to be useful in gully erosion. Moreover, it provides a solid ground for additional applications in geosciences such as surface roughness measurements, quantification of gravitational mass movements or capturing stream connectivity. During field campaigns in semiarid southern Morocco a commercial DSLR camera was used, to produce images that served as input data for software based point cloud and mesh generation. Thus, complex land surfaces could be reconstructed entirely in high resolution by photographing the object from different perspectives. In different scales the resulting 3D-mesh represents a holistic reconstruction of the actual shape complexity with its limits set only by computing capacity. Analysis and visualization of time series of different erosion-related events illustrate the additional benefit of the method. It opens new perspectives on process understanding that can be exploited by open source and commercial software. Results depicted a soil loss of 5

  19. Numerical modelling study of gully recharge and debris flows in Haida Gwaii, British Columbia

    NASA Astrophysics Data System (ADS)

    Martin, Yvonne; Johnson, Edward; Chaikina, Olga

    2015-04-01

    In high mountains, debris flows are a major process responsible for transferring sediment to more downstream fluvial reaches. This sediment transfer begins on mountain hillslopes where various mass wasting processes move sediment from hillslopes to uppermost reaches of the channel system (these reaches are herein referred to as gullies and only experience water flow during high intensity precipitation events). Sediment recharge into gullies, which has received minimal attention in the scientific literature, refers to the transfer of sediment and other debris from surrounding hillslopes into gullies (Jakob and Oden, 2005). Debris flow occurrence and debris flow volumes depend on some precipitation threshold as well as volumes of material contained in the particular gully. For example, if one debris flow has removed all of the accumulated material from the gully, then any subsequent debris flow will be smaller if enough time has not yet passed for notable sediment recharge. Herein, we utilize the numerical model of landscape development, LandMod (Martin, 1998; Dadson and Church, 2005; Martin, 2007), to explore connections between hillslope processes, gully recharge rates, and transfer of sediment to downstream channel reaches in the Haida Gwaii, British Columbia. Hillslope processes in the model include shallow landsliding, bedrock failures and weathering. The updated debris flow algorithm is based on extensive field data available for debris flows in Haida Gwaii (e.g., Rood, 1984; Oden, 1994; Jakob and Oden, 2005), as well as theoretical considerations based on debris flow studies. The most significant model extension is the calculation of gully recharge rates; for each gully, the total accumulated sediment in gullies at each time step is determined using a power-law relation for area-normalized recharge rate versus elapsed time since the last debris flow. Thus, when the stochastic driver for debris flow occurrence triggers an event, the amount of stored material is

  20. Use of an in vitro flat-bed biofilm model to measure biologically active anti-odour compounds.

    PubMed

    Saad, S; Hewett, K; Greenman, J

    2013-09-01

    The objective of this study was to demonstrate the utility of a modified flat-bed perfusion biofilm matrix system for testing toothpaste formulations directly, without dilution, as a layer in direct contact with the biofilm matrix surface. Final biofilm yields and volatile sulphur compounds (VSC) biogenesis were measured to show the relative efficacy of toothpaste formulations. Diffusion characteristics of the flat-bed system to exposure with Meridol® tooth and tongue gel (TTG; 1,400 ppm F(-) from amine fluoride/stannous fluoride, 0.5 % zinc lactate, oral malodour counteractives) was assessed using a bioluminescent target species Escherichia coli Nissle 1917/pGLITE coupled with a low-light photon camera to visualise the kill kinetics. Tongue-flora derived, mixed culture biofilms (n = 4) received 5, 15 and 30 min treatment with TTG, respectively, to determine the optimum time of exposure. VSC biogenesis was measured from headspace samples by gas chromatography prior to and following treatment of two daily applications for 4 days of treatment (TTG), positive control (CHX gel) and negative controls (placebo and sham treatment). Viable counts were performed at the end of experiments by destructive sampling of the biofilms and plating onto selective and non-selective agar. Following a single treatment with TTG, the E. coli biofilm with lux target gave >50 % reduction of luminescence within 2 to 3 h before recovering to a steady state over 10 h, suggesting biofilm cidal activity rather biostasis. For mixed culture biofilms, 15- and 30-min treatment exposure with TTG gave almost identical reductions in final biofilm yields. For comparing efficacy of treatments, biofilms treated with TTG gave greatest reductions in both pre-post levels of H2S (P < 0.01) and CH3SH (P < 0.05) and population yields at the end of the experiments (P < 0.001) compared to placebo and positive control. The in vitro flat-bed perfusion model may be used to replicate many of

  1. Use of an in vitro flat-bed biofilm model to measure biologically active anti-odour compounds.

    PubMed

    Saad, S; Hewett, K; Greenman, J

    2013-09-01

    The objective of this study was to demonstrate the utility of a modified flat-bed perfusion biofilm matrix system for testing toothpaste formulations directly, without dilution, as a layer in direct contact with the biofilm matrix surface. Final biofilm yields and volatile sulphur compounds (VSC) biogenesis were measured to show the relative efficacy of toothpaste formulations. Diffusion characteristics of the flat-bed system to exposure with Meridol® tooth and tongue gel (TTG; 1,400 ppm F(-) from amine fluoride/stannous fluoride, 0.5 % zinc lactate, oral malodour counteractives) was assessed using a bioluminescent target species Escherichia coli Nissle 1917/pGLITE coupled with a low-light photon camera to visualise the kill kinetics. Tongue-flora derived, mixed culture biofilms (n = 4) received 5, 15 and 30 min treatment with TTG, respectively, to determine the optimum time of exposure. VSC biogenesis was measured from headspace samples by gas chromatography prior to and following treatment of two daily applications for 4 days of treatment (TTG), positive control (CHX gel) and negative controls (placebo and sham treatment). Viable counts were performed at the end of experiments by destructive sampling of the biofilms and plating onto selective and non-selective agar. Following a single treatment with TTG, the E. coli biofilm with lux target gave >50 % reduction of luminescence within 2 to 3 h before recovering to a steady state over 10 h, suggesting biofilm cidal activity rather biostasis. For mixed culture biofilms, 15- and 30-min treatment exposure with TTG gave almost identical reductions in final biofilm yields. For comparing efficacy of treatments, biofilms treated with TTG gave greatest reductions in both pre-post levels of H2S (P < 0.01) and CH3SH (P < 0.05) and population yields at the end of the experiments (P < 0.001) compared to placebo and positive control. The in vitro flat-bed perfusion model may be used to replicate many of

  2. Topographic and road control of mega-gullies in Kinshasa (DR Congo)

    NASA Astrophysics Data System (ADS)

    Makanzu Imwangana, Fils; Dewitte, Olivier; Ntombi, Médard; Moeyersons, Jan

    2014-07-01

    Diachronic mapping (1957, 1967, 2007 and 2010) shows an exponentially growing mega-gully network since roads were constructed through in the forests and plantations which occupied the sandy soils of the high town of Kinshasa. We found that the spatial occurrence of the mega-gullies (width ≥ 5 m) in this newly urbanized environment is controlled by two factors. First, there is a topographic control, given by the relation S = 0.00008A- 1.459, with S being the slope gradient (m m- 1) of the soil surface at the gully head and A the drainage area (ha) above the head. There is also a ‘road’ control, expressed by S = 22.991Lc- 1.999, with Lc being the cumulated length of roads in the basin above the gully head. The co-existence of both controls reflects the fact that the local sands are highly permeable and hence roads are more important generators of continuous runoff. The S-A relation noted above should not be applied outside the town where the road network is less dense. In contrast, the S-Lc relation may be used in both the town and rural areas underlain by porous soils where roads are the only generators of continuous runoff. We further conclude that the high town of Kinshasa is one of the most vulnerable places for gullying, and gullying can potentially transform the town into a badland. ‘Artisanal’ gully treatment is more successful than generally believed and the S-Lc relation can be a tool for mega-gully prevention.

  3. Predicting gully rejuvenation after wildfire using remotely sensed burn severity data

    NASA Astrophysics Data System (ADS)

    Hyde, Kevin; Woods, Scott W.; Donahue, Jack

    2007-05-01

    The loss of surface vegetation and reduced infiltration caused by wildfires can trigger gully rejuvenation, resulting in damage to downstream aquatic resources and risk to human life and property. We developed a spatially explicit metric of burn severity — the Burn Severity Distribution Index (BSDI) — and tested its ability to predict post-fire gully rejuvenation in 1st and 2nd order basins burned in the 2000 Valley Complex fires in the Sapphire Mountains of western Montana. The BSDI was derived from burn severity data interpreted from Landsat 7 satellite imagery using the Normalized Burn Ratio (NBR) method, and ranged from 0.0 for completely unburned basins to 4.0 for basins burned entirely at high severity. In July 2001 rainstorms with peak 30-minute intensities of up to 17 mm h - 1 triggered gully rejuvenation in 66 of the 171 basins examined. The frequency of gully rejuvenation was higher in basins with higher BSDI values, increasing from zero for basins with a BSDI less than 1.3 to 67% for basins with a BSDI greater than 3.0. Binary logistic regression indicated that BSDI was a more significant predictor of gully rejuvenation than basin morphometric variables. The absence of gully rejuvenation in several basins with a high BSDI was attributed to low gradient, dense riparian vegetation, or concentration of high burn severity at lower elevations in the basin. The presence of gully rejuvenation in several basins with a low BSDI was associated with false negative NBR classification errors in northwest aspects, and concentration of severe burn impacts in the drainage headslopes. BSDI is a useful metric for predicting gully rejuvenation after wildfire. The use of the BSDI in Burned Area Emergency Response team assessments could improve the planning, implementation, and monitoring of burned area recovery treatments.

  4. Evaluation of a gully headcut retreat model using multitemporal aerial photographs and digital elevation models

    NASA Astrophysics Data System (ADS)

    Campo-Bescós, M. A.; Flores-Cervantes, J. H.; Bras, R. L.; Casalí, J.; Giráldez, J. V.

    2013-12-01

    large fraction of soil erosion in temperate climate systems proceeds from gully headcut growth processes. Nevertheless, headcut retreat is not well understood. Few erosion models include gully headcut growth processes, and none of the existing headcut retreat models have been tested against long-term retreat rate estimates. In this work the headcut retreat resulting from plunge pool erosion in the Channel Hillslope Integrated Landscape Development (CHILD) model is calibrated and compared to long-term evolution measurements of six gullies at the Bardenas Reales, northeast Spain. The headcut retreat module of CHILD was calibrated by adjusting the shape factor parameter to fit the observed retreat and volumetric soil loss of one gully during a 36 year period, using reported and collected field data to parameterize the rest of the model. To test the calibrated model, estimates by CHILD were compared to observations of headcut retreat from five other neighboring gullies. The differences in volumetric soil loss rates between the simulations and observations were less than 0.05 m3 yr-1, on average, with standard deviations smaller than 0.35 m3 yr-1. These results are the first evaluation of the headcut retreat module implemented in CHILD with a field data set. These results also show the usefulness of the model as a tool for simulating long-term volumetric gully evolution due to plunge pool erosion.

  5. Formation of gullies on Mars by debris flows triggered by CO2 sublimation

    NASA Astrophysics Data System (ADS)

    Pilorget, C.; Forget, F.

    2016-01-01

    Martian gully landforms resemble terrestrial debris flows formed by the action of liquid water and have thus been interpreted as evidence for potential habitable environments on Mars within the past few millennia. However, ongoing gully formation has been detected under surface conditions much too cold for liquid water, but at times in the martian year when a thin layer of seasonal CO2 frost is present and defrosting above the regolith. These observations suggest that the CO2 condensation-sublimation cycle could play a role in gully formation. Here we use a thermo-physical numerical model of the martian regolith underlying a CO2 ice layer and atmosphere to show that the pores beneath the ice layer can be filled with CO2 ice and subjected to extreme pressure variations during the defrosting season. The subsequent gas fluxes can destabilize the regolith material and induce gas-lubricated debris flows with geomorphic characteristics similar to martian gullies. Moreover, we find that subsurface CO2 ice condensation, sublimation and pressurization occurs at conditions found at latitudes and slope orientations where gullies are observed. We conclude that martian gullies can result from geologic dry ice processes that have no terrestrial analogues and do not require liquid water. Such dry ice processes may have helped shape the evolution of landforms elsewhere on the martian surface.

  6. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic. PMID:26093257

  7. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic.

  8. Treatment of gas industry wastes using the biological granular activated carbon fluidized bed reactor process. Annual report, August 1994

    SciTech Connect

    Hickey, R.; Wagner, D.; Sunday, A.; Heine, B.; Rajan, R.

    1994-08-01

    The Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) system is a high rate process that combines the advantages of biological and physical-chemical treatment in a single unit operation. The process is particularly well-suited to treatment of contaminants present in water and wastewater at relatively low concentrations. Process economics indicate the GAC-FBR can be extremely cost-effective compared to aqueous phase GAC adsorption and air stripping followed by vapor phase control. Accordingly, three field trials are scheduled for the next 18 months; one at a manufactured gas plant site (PAHs), one at a gas dehydration site (BTEX), and one to treat a chlorinated solvent (TCE) at a government installation.

  9. Factors controlling gully erosion at different spatial and temporal scales in rangelands of SW Spain

    NASA Astrophysics Data System (ADS)

    Gómez Gutiérrez, Á.; Schnabel, S.; Lavado Contador, J. F.; Pulido Fernández, M.

    2009-04-01

    Gully erosion has been recognized as an important soil degradation process in rangelands of SW Spain. However, little is known about gullying processes at different spatial and temporal scales in these areas. Three different approaches were used in this paper to analyze the factors determining gully erosion intensity and rates at different spatial and temporal scales in rangelands of SW Spain. The first approach was based on the monitoring of a permanent valley bottom gully and continuous measurement of rainfall and discharge during the period 2001-2007 in the Parapuños experimental basin. Parapuños is a small catchment (99.5 ha) representative of dehesa land use, with an undulated topography and Mediterranean climate. Gully erosion volume was obtained by means of 28 fixed cross sections measured with a frequency of 6 months. Discharge and rainfall were monitored using a water depth probe installed in a weir at the outlet of the catchment and 6 tipping bucket rain gauges, respectively. The second approach was based on analyzing the development of the same permanent gully located in Parapuños using six series of aerial ortophotographs for the period 1945-2006. This methodology allowed to relate gully evolution with land use and vegetation cover changes. Finally, a relatively new data mining technique, called Multivariate Adaptive Regression Splines (MARS), was applied to construct a model capable of predicting the location of gullies at the regional scale. A large database composed of 36 independent variables related to topography, lithology, soils, rainfall, land use and vegetation cover was used. This statistical technique allowed to determine the importance of the variables involved. This database was gathered in 46 farms representative of rangelands of SW Spain in Extremadura, covering a surface area of 35,459 ha. Farms were quite diverse although their main characteristics were undulating landforms, acid rocks (schists, greywackes and granites), and

  10. Formation of gullies on Mars: link to recent climate history and insolation microenvironments implicate surface water flow origin.

    PubMed

    Head, James W; Marchant, David R; Kreslavsky, Mikhail A

    2008-09-01

    Features seen in portions of a typical midlatitude Martian impact crater show that gully formation follows a geologically recent period of midlatitude glaciation. Geological evidence indicates that, in the relatively recent past, sufficient snow and ice accumulated on the pole-facing crater wall to cause glacial flow and filling of the crater floor with debris-covered glaciers. As glaciation waned, debris-covered glaciers ceased flowing, accumulation zones lost ice, and newly exposed wall alcoves continued as the location for limited snow/frost deposition, entrapment, and preservation. Analysis of the insolation geometry of this pole-facing crater wall, and similar occurrences in other craters at these latitudes on Mars, shows that they are uniquely favored for accumulation of snow and ice, and a relatively more rapid exposure to warmer summer temperatures. We show that, after the last glaciation, melting of residual snow and ice in alcoves could have formed the fluvial channels and sedimentary fans of the gullies. Recent modeling shows that top-down melting can occur in these microenvironments under conditions similar to those currently observed on Mars, if small amounts of snow or frost accumulate in alcoves and channels. Accumulation and melting is even more favored in the somewhat wetter, relatively recent geological past of Mars, after the period of active glaciation. PMID:18725636

  11. Formation of gullies on Mars: Link to recent climate history and insolation microenvironments implicate surface water flow origin

    PubMed Central

    Head, James W.; Marchant, David R.; Kreslavsky, Mikhail A.

    2008-01-01

    Features seen in portions of a typical midlatitude Martian impact crater show that gully formation follows a geologically recent period of midlatitude glaciation. Geological evidence indicates that, in the relatively recent past, sufficient snow and ice accumulated on the pole-facing crater wall to cause glacial flow and filling of the crater floor with debris-covered glaciers. As glaciation waned, debris-covered glaciers ceased flowing, accumulation zones lost ice, and newly exposed wall alcoves continued as the location for limited snow/frost deposition, entrapment, and preservation. Analysis of the insolation geometry of this pole-facing crater wall, and similar occurrences in other craters at these latitudes on Mars, shows that they are uniquely favored for accumulation of snow and ice, and a relatively more rapid exposure to warmer summer temperatures. We show that, after the last glaciation, melting of residual snow and ice in alcoves could have formed the fluvial channels and sedimentary fans of the gullies. Recent modeling shows that top-down melting can occur in these microenvironments under conditions similar to those currently observed on Mars, if small amounts of snow or frost accumulate in alcoves and channels. Accumulation and melting is even more favored in the somewhat wetter, relatively recent geological past of Mars, after the period of active glaciation. PMID:18725636

  12. Time in Bed is Associated with Decreased Physical Activity and Higher BMI in Women Seeking Weight Loss Treatment.

    PubMed

    Hart, Chantelle N; Fava, Joseph L; Subak, Leslee L; Stone, Katie; Vittinghoff, Eric; Demos, Kathryn; O'Brien, Erin; Cairns, Alyssa; Wing, Rena

    2012-01-01

    Short sleep duration is associated with obesity risk. Despite calls to incorporate strategies to enhance sleep within the context of behavioral weight loss (BWL) treatment, little is known regarding the association between sleep and body mass index (BMI) among individuals presenting for BWL. Moreover, most research has focused on eating pathways linking sleep and BMI, and have not explored how sleep may impact engagement in physical activity. The purpose of the present study was to determine whether, in a sample of women seeking treatment for weight loss, there was an association between reported time in bed (TIB), higher BMI, lower physical activity, and less favorable dietary composition. Prior to randomization, 318 women completed measures of TIB, eating, and activity; weight and height were measured. Findings demonstrated that report of '6 hours or less' TIB/night was associated with higher BMI and lower reported physical activity compared to the referent (>7 to ≤ 8 hours/night). It was not associated with the number of reported calories consumed each day or with the percent of calories consumed from fat, carbohydrates or protein. Better understanding the role of sleep within the context of BWL treatment in women seems warranted.

  13. Alkali activation of recovered fuel-biofuel fly ash from fluidised-bed combustion: Stabilisation/solidification of heavy metals.

    PubMed

    Yliniemi, Juho; Pesonen, Janne; Tiainen, Minna; Illikainen, Mirja

    2015-09-01

    Recovered fuel-biofuel fly ash from a fluidized bed boiler was alkali-activated and granulated with a sodium-silicate solution in order to immobilise the heavy metals it contains. The effect of blast-furnace slag and metakaolin as co-binders were studied. Leaching standard EN 12457-3 was applied to evaluate the immobilisation potential. The results showed that Ba, Pb and Zn were effectively immobilised. However, there was increased leaching after alkali activation for As, Cu, Mo, Sb and V. The co-binders had minimal or even negative effect on the immobilisation. One exception was found for Cr, in which the slag decreased leaching, and one was found for Cu, in which the slag increased leaching. A sequential leaching procedure was utilized to gain a deeper understanding of the immobilisation mechanism. By using a sequential leaching procedure it is possible fractionate elements into watersoluble, acid-soluble, easily-reduced and oxidisable fractions, yielding a total 'bioavailable' amount that is potentially hazardous for the environment. It was found that the total bioavailable amount was lower following alkali activation for all heavy metals, although the water-soluble fraction was higher for some metals. Evidence from leaching tests suggests the immobilisation mechanism was chemical retention, or trapping inside the alkali activation reaction products, rather than physical retention, adsorption or precipitation as hydroxides. PMID:26054963

  14. Activation of Canadian coals in a fixed-bed reactor: effect of the particle size on product quality

    SciTech Connect

    Ajay K. Dalai; Narayan C. Pradhan; Jian Liu; Amitabha Majumdar; Eric L. Tollefson

    2008-07-15

    Three Canadian coals, namely, Bienfait lignite, Montgomery sub-bituminous C, and Coal Valley high volatile bituminous C were activated in a fixed-bed reactor. For each coal, two different sizes of particles in the ranges of 0-1.25 mm (fines) and 1.25-2.5 mm (granules) along with cylindrical pellets of 3.18 mm in diameter and 7{+-}2 mm long were activated. The qualities of the products were determined by measuring iodine and methylene blue numbers, specific Brunauer-Emmett-Teller (BET) surface areas, bulk densities, and ash contents. The specific surface areas and iodine and methylene blue numbers of bituminous coal products were lower than the values obtained with the lignite and sub-bituminous coals, although the product yields were higher. Products obtained from pellets were found to have superior quality compared to that obtained from fines. The ash content of the feed coal influences the quality of the product activated carbon. It was established that a first-order reaction between steam and coal pellets occurred in the process. The activation energies for the process were also determined. 17 refs., 12 figs., 4 tabs.

  15. Cannabidiol injected into the bed nucleus of the stria terminalis modulates baroreflex activity through 5-HT1A receptors.

    PubMed

    Alves, Fernando H F; Crestani, Carlos C; Gomes, Felipe V; Guimarães, Francisco S; Correa, Fernando M A; Resstel, Leonardo B M

    2010-09-01

    Cannabidiol (CBD) is a non-psychotomimetic constituent of the Cannabis sativa plant that inhibits behavioral and cardiovascular responses to aversive situations, facilitating 5-HT1A-mediated neurotransmission. Previous results from our group suggest that the bed nucleus of the stria terminalis (BNST) may be involved in CBD's anti-aversive effects. To investigate whether the cardiovascular effects of the CBD could involve a direct drug effect on the BNST, we evaluated the effects of CBD microinjection into this structure on baroreflex activity. We also verified whether these effects were mediated by the activation of 5-HT(1A) receptors. Bilateral microinjection of CBD (60 nmol/100 nL) into the BNST increased the bradycardiac response to arterial pressure increases. However, no changes were observed in tachycardiac responses evoked by arterial pressure decreases. Pretreatment of the BNST with the selective 5-HT(1A) receptor antagonist WAY100635 (0.37 nmol/100 nL) prevented CBD effects on the baroreflex activity. Moreover, microinjection of the 5-HT(1A) receptor agonist 8-OH-DPAT (4 nmol/100 nL) caused effects that were similar to those observed after the microinjection of CBD, which were also blocked by pretreatment with WAY100635. In conclusion, the present studies show that the microinjection of CBD into the BNST has a facilitatory influence on the baroreflex response to blood pressure increases, acting through the activation of 5-HT1A receptors. PMID:20621717

  16. Effects of resource activities upon repository siting and waste containment with reference to bedded salt

    SciTech Connect

    Ashby, J.; Rowe, J.

    1980-02-01

    The primary consideration for the suitability of a nuclear waste repository site is the overall ability of the repository to safely contain radioactive waste. This report is a discussion of the past, present, and future effects of resource activities on waste containment. Past and present resource activities which provide release pathways (i.e., leaky boreholes, adjacent mines) will receive initial evaluation during the early stages of any repository site study. However, other resource activities which may have subtle effects on containment (e.g., long-term pumping causing increased groundwater gradients, invasion of saline water causing lower retardation) and all potential future resource activities must also be considered during the site evaluation process. Resource activities will affect both the siting and the designing of repositories. Ideally, sites should be located in areas of low resource activity and low potential for future activity, and repository design should seek to eliminate or minimize the adverse effects of any resource activity. Buffer zones should be created to provide areas in which resource activities that might adversely affect containment can be restricted or curtailed. This could mean removing large areas of land from resource development. The impact of these frozen assets should be assessed in terms of their economic value and of their effect upon resource reserves. This step could require a major effort in data acquisition and analysis followed by extensive numerical modeling of regional fluid flow and mass transport. Numerical models should be used to assess the effects of resource activity upon containment and should include the cumulative effects of different resource activities. Analysis by other methods is probably not possible except for relatively simple cases.

  17. Interfacial liquid water on Mars and its potential role in formation of hill and dune gullies

    NASA Astrophysics Data System (ADS)

    Kossacki, Konrad J.; Markiewicz, Wojciech J.

    2010-11-01

    Gullies are among the most intriguing structures identified on the surface of Mars. Most common are gullies located on the slopes of craters which are probably formed by liquid water transported by shallow aquifers (Heldmann, J.L., Carlsson, E., Johansson, H., Mellon, M.T., Toon, O.B. [2007]. Icarus 188, 324-344). Two particular types of gullies are found on slopes of isolated hills and dunes. The hill-slope gullies are located mostly at 50°S, which is at the high end of latitudes of bulk of the gullies found so far. The dune gullies are found in several locations up to 65°S (Reiss, D., Jaumann, R., Kereszturi, A., Sik, A., Neukum, G. [2007]. Lunar Planet. Sci. XXXVIII. Abstract 1993), but the best known are those in Russel crater at 54°S. The hill and dune gullies are longer than others making the aquifers explanation for their formation unlikely (Balme, M., Mangold, N., Baratoux, D., Costard, F., Gosselin, M., Masson, P., Pnet, P., Neukum, G. [2006]. J. Geophys. Res. 111. doi:10.1029/2005JE002607). Recently it has been noted that thin liquid films of interfacial water can play a role in rheological processes on the surface of Mars (Moehlmann, D. [2008]. Icarus 195, 131-139. Kereszturi, A., Moehlmann, D., Berczi, Sz., Ganti, T., Kuti, A., Sik, A., Horvath, A. [2009]. Icarus 201, 492-503.). Here we try to answer the question whether interfacial liquid water may occur on Mars in quantities large enough to play a role in formation of gullies. To verify this hypothesis we have calculated thermal models for hills and dunes of various steepness, orientation and physical properties. We find that within a range of average expected values of parameters it is not possible to have more than a few monolayers of liquid water at depths greater than a centimeter. To create subsurface interfacial water film significantly thicker and hence to produce conditions for the slope instability, parameters have to be chosen to have their extreme realistic values or an additional source

  18. Determining gully volume from straightforward photo-based 3D reconstruction

    NASA Astrophysics Data System (ADS)

    James, M. R.; Castillo, C.; Pérez, R.; Taguas, E. V.; Gomez, J. A.; Quinton, J. N.

    2012-04-01

    In order to quantify soil loss through gully erosion, accurate measurements of gully volume are required. However, gullys are usually extended features, often with complex morphologies and are challenging to survey appropriately and efficiently. Here we explore the use of a photo-based technique for deriving 3D gully models suitable for detailed erosion studies. Traditional aerial and oblique close-range photogrammetry approaches have been previously used to produce accurate digital elevation models (DEMs) from photographs. However, these techniques require expertise to carry out successfully, use proprietry software and usually need apriori camera calibration. The computer vision approach we adopt here relaxes these requirements and allows 3D models to be automatically produced from collections of unordered photos. We use a freely available 'reconstruction pipeline' (http://blog.neonascent.net/archives/bundler-photogrammetry-package/) that combines structure-from-motion and multi-view stereo algorithms (SfM-MVS) to generate dense point clouds (millions of points). The model is derived from photos taken from different positions with a consumer camera and is then scaled and georeferenced using additional software (http://www.lancs.ac.uk/staff/jamesm/software/sfm_georef.htm) and observations of some control points in the scene. The approach was tested on a ~7-m long sinous gully section (average width and depth ~2.4 and 1.2 m respectively) in Vertisol soils, near Cordoba, Spain. For benchmark data, the gully topography was determined with a terrestrial laser scanner (Riegl LMS-Z420i, with a cited range accuracy of 10 mm). 191 photos were taken with a Canon EOS 450D with a prime (fixed) 28 mm lens over a period of ~10 minutes. In order to georeference the SfM-MVS model for comparison with the TLS data, 6 control targets were located around the gully and their locations determined by dGPS. Differences between the TLS and SfM-MVS surfaces are dominated by areas of data

  19. Soil moisture estimation by airborne active and passive microwave remote sensing: A test-bed for SMAP fusion algorithms

    NASA Astrophysics Data System (ADS)

    Montzka, Carsten; Bogena, Heye; Jagdhuber, Thomas; Hajnsek, Irena; Horn, Ralf; Reigber, Andreas; Hasan, Sayeh; Rüdiger, Christoph; Jaeger, Marc; Vereecken, Harry

    2014-05-01

    The objective of the NASA Soil Moisture Active & Passive (SMAP) mission is to provide global measurements of soil moisture and its freeze/thaw state. The SMAP launch is currently planned for 2014-2015. The SMAP measurement approach is to integrate L-band radar and L-band radiometer as a single observation system combining the respective strengths of active and passive remote sensing for enhanced soil moisture mapping. The radar and radiometer measurements can be effectively combined to derive soil moisture maps that approach the accuracy of radiometer-only retrievals, but with a higher resolution (being able to approach the radar resolution under some conditions). Aircraft and tower-based instruments will be a key part of the SMAP validation program. Here, we present an airborne campaign in the Rur catchment in Germany, in which the passive L-band system Polarimetric L-band Multi-beam Radiometer (PLMR2) and the active L-band system DLR F-SAR were flown on six dates in 2013. The flights covered the full heterogeneity of the area under investigation, i.e. all types of land cover and experimental monitoring sites. These data are used as a test-bed for the analysis of existing and development of new active-passive fusion techniques. A synergistic use of the two signals can help to decouple soil moisture effects from the effects of vegetation (or roughness) in a better way than in the case of a single instrument. In this study, we present and evaluate three approaches for the fusion of active and passive microwave records for an enhanced representation of the soil moisture status: i) estimation of soil moisture by passive sensor data and subsequent disaggregation by active sensor backscatter data, ii) disaggregation of passive microwave brightness temperature by active microwave backscatter and subsequent inversion to soil moisture, and iii) fusion of two single-source soil moisture products from radar and radiometer.

  20. Topographic thresholds in gully development on the hillslopes of communal areas in Ngqushwa Local Municipality, Eastern Cape, South Africa

    NASA Astrophysics Data System (ADS)

    Kakembo, V.; Xanga, W. W.; Rowntree, K.

    2009-09-01

    The relationships between the spatial distribution of gully erosion and topographic thresholds in the form of slope angle, position and configuration, as well as land use change in the form of abandoned lands were examined in several affected catchments of the Eastern Cape Province, South Africa. Land use and permanent gullies were mapped, digitized from orthophoto maps in Arc/info 3.5.2 GIS and converted to shapefiles using ArcView 3.2 GIS. Relationships between the mapped phenomena and topographic variables were sought using a Digital Elevation Model (DEM) in Idrisi Kilimanjaro GIS. A comparison between areas with a high potential for gullying and actual gully erosion was made using the Stream Power Index ( SPI) as a surrogate for critical flow shear stress. Field surveys were also conducted to assess the present condition of the gullied sites as well as to validate DEM derivations. Seventy five percent of the gullied area was noted to lie on abandoned lands. A predominance of gullying in concave bottom lands was also identified. The SPI values highlighted a distinct preferential topographic zone for gully location. A conceptual model depicting the interaction between land use and topographic parameters to induce gully erosion was developed. This should assist local authorities to develop a policy regarding management of abandoned lands.

  1. Activation of galanin pathways across puberty in the male rat: galanin gene expression in the bed nucleus of the stria terminalis and medial amygdala.

    PubMed

    Planas, B; Kolb, P E; Raskind, M A; Miller, M A

    1994-12-01

    Galanin and vasopressin are coexpressed in the bed nucleus of the stria terminalis and medial amygdala of the male rat. In adult males, the level of gene expression for both peptides in these regions is dependent on circulating levels of testosterone. We hypothesized that galanin messenger RNA levels would be enhanced in adult males compared with prepubertal males due to the rise in plasma testosterone levels. We used in situ hybridization and quantitative autoradiography to measure galanin messenger RNA in cells of the bed nucleus of the stria terminalis and medial amygdala of prepubertal and adult male rats. Our results show that significantly (P < or = 0.05) more galanin messenger RNA expressing neurons are detectable in the bed nucleus of the stria terminalis of adult compared with prepubertal male rats. In contrast, no differences were observed between the groups in the number of labeled neurons detected within the medial amygdala. However, the average labeling intensity was significantly enhanced in both the bed nucleus of the stria terminalis (P < or = 0.001) and medial amygdala (P < or = 0.001) of adult compared with prepubertal animals. The present findings are consistent with the hypothesis that gonadal hormones regulate galanin gene expression in some brain regions and suggest that the activation of the hypothalamic-pituitary-gonadal axis which occurs naturally with puberty is associated with activation of galanin pathways in the bed nucleus of the stria terminalis and medial amygdala.

  2. Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

    USGS Publications Warehouse

    Michot, T.C.; Woodin, M.C.; Adair, S.E.; Moser, E.B.

    2006-01-01

    Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre) and from ponds adjacent to the Laguna Madre. Activities differed (p<0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, whereas drinking was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially because of weather differences (colder temperatures in Louisiana), but the location effect was still significant even when we adjusted the model for weather effects. Redheads in Louisiana showed increased resting and decreased feeding as winter progressed, but redheads in Texas did not exhibit a seasonal pattern in either resting or feeding. In Louisiana, birds maintained a high level of feeding activity during the early morning throughout the winter, whereas afternoon feeding tapered off in mid- to late-winter. Texas birds showed a shift from morning feeding in early winter to afternoon feeding in late winter. Males and females at both Chandeleur Sound and Laguna Madre showed differences in their activities, but because the absolute difference seldom exceeded 2%, biological significance is questionable. Diurnal time-activity budgets of redheads on the wintering grounds are influenced by water salinities and the use of dietary fresh water, as well as by weather conditions, tides, and perhaps vegetation differences between sites. The opportunity to osmoregulate via dietary freshwater, vs. via nasal salt glands, may have a significant effect on behavioral allocations. ?? Springer 2006.

  3. Bed exit alarms.

    PubMed

    2004-09-01

    Bed-exit alarms alert caregivers that a patient who should not get out of bed unassisted is doing so. These alarms can help reduce the likelihood of falls and can promote speedy assistance to patients who have already fallen. But as we described in our May 2004 Guidance Article on bed-exit alarms, they don't themselves prevent falls. They are only effective if used as part of an overall fall-prevention program and with a clear understanding of their limitations. This Evaluation examines the effectiveness of 16 bed-exit alarms from seven suppliers. Our ratings focus primarily on each product's reliability in detecting bed-exit events and alerting caregivers, its ability to minimize nuisance alarms (alarms that sound even though the patient isn't leaving the bed or that sound while a caregiver is helping the patient to leave the bed), and its resistance to deliberate or inadvertent tampering. Twelve of the products use pressure-sensor-activated alarms (mainly sensor pads placed on or under the mattress); three use a cord that can attach to the patient's garment, alarming if the cord is pulled loose from the control unit; and one is a position-sensitive alarm attached to a leg cuff. All the products reliably detect attempted or successful bed exits. But they vary greatly in how effectively they alert staff, minimize nuisance alarms, and resist tampering. Ease of use and battery performance also vary for many units. Of the pressure-sensor units, three are rated Preferred. Those units meet most of our criteria and have no significant disadvantages. Five of the other pressure-sensor products are Acceptable, and the remaining four are Not Recommended. All three cord-activated alarms are rated Acceptable, as is the patient-worn alarm.

  4. Evidence for debris flow gully formation initiated by shallow subsurface water on Mars

    USGS Publications Warehouse

    Lanza, N.L.; Meyer, G.A.; Okubo, C.H.; Newsom, Horton E.; Wiens, R.C.

    2010-01-01

    The morphologies of some martian gullies appear similar to terrestrial features associated with debris flow initiation, erosion, and deposition. On Earth, debris flows are often triggered by shallow subsurface throughflow of liquid water in slope-mantling colluvium. This flow causes increased levels of pore pressure and thus decreased shear strength, which can lead to slide failure of slope materials and subsequent debris flow. The threshold for pore pressure-induced failure creates a distinct relationship between the contributing area supplying the subsurface flow and the slope gradient. To provide initial tests of a similar debris flow initiation hypothesis for martian gullies, measurements of the contributing areas and slope gradients were made at the channel heads of martian gullies seen in three HiRISE stereo pairs. These gullies exhibit morphologies suggestive of debris flows such as leveed channels and lobate debris fans, and have well-defined channel heads and limited evidence for multiple flows. Our results show an area-slope relationship for these martian gullies that is consistent with that observed for terrestrial gullies formed by debris flow, supporting the hypothesis that these gullies formed as the result of saturation of near-surface regolith by a liquid. This model favors a source of liquid that is broadly distributed within the source area and shallow; we suggest that such liquid could be generated by melting of broadly distributed icy materials such as snow or permafrost. This interpretation is strengthened by observations of polygonal and mantled terrain in the study areas, which are both suggestive of near-surface ice. ?? 2009 Elsevier Inc.

  5. Standardization in gully erosion studies: methodology and interpretation of magnitudes from a global review

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Gomez, Jose Alfonso

    2016-04-01

    Standardization is the process of developing common conventions or proceedings to facilitate the communication, use, comparison and exchange of products or information among different parties. It has been an useful tool in different fields from industry to statistics due to technical, economic and social reasons. In science the need for standardization has been recognised in the definition of methods as well as in publication formats. With respect to gully erosion, a number of initiatives have been carried out to propose common methodologies, for instance, for gully delineation (Castillo et al., 2014) and geometrical measurements (Casalí et al., 2015). The main aims of this work are: 1) to examine previous proposals in gully erosion literature implying standardization processes; 2) to contribute with new approaches to improve the homogeneity of methodologies and presentation of results for a better communication among the gully erosion community. For this purpose, we evaluated the basic information provided on environmental factors, discussed the delineation and measurement procedures proposed in previous works and, finally, we analysed statistically the severity of degradation levels derived from different indicators at the world scale. As a result, we presented suggestions aiming to serve as guidance for survey design as well as for the interpretation of vulnerability levels and degradation rates for future gully erosion studies. References Casalí, J., Giménez, R., and Campo-Bescós, M. A.: Gully geometry: what are we measuring?, SOIL, 1, 509-513, doi:10.5194/soil-1-509-2015, 2015. Castillo C., Taguas E. V., Zarco-Tejada P., James M. R., and Gómez J. A. (2014), The normalized topographic method: an automated procedure for gully mapping using GIS, Earth Surf. Process. Landforms, 39, 2002-2015, doi: 10.1002/esp.3595

  6. Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

    USGS Publications Warehouse

    Anderson, N.L.; Hopkins, J.; Martinez, A.; Knapp, R.W.; Macfarlane, P.A.; Watney, W.L.; Black, R.

    1994-01-01

    Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: 1. (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the

  7. Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

    NASA Astrophysics Data System (ADS)

    Anderson, Neil L.; Hopkins, John; Martinez, Alex; Knapp, Ralph W.; Macfarlane, P. Allan; Watney, W. Lynn; Black, Ross

    1994-06-01

    Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the

  8. MODELING THE INFLUENCE OF ACTIVE SUBSLAB DEPRESSURIZATION (ASD) SYSTEMS ON AIRFLOWS IN SUBSLAB AGGREGATE BEDS

    EPA Science Inventory

    A simple model is presented that allows the pressure difference in a subslab aggregate layer to be estimated as a function of radial distance from the central suction point of an active subslab depressurization system by knowing the average size, thickness, porosity, and permeabi...

  9. Seasonal composition and activity of sulfate-reducing prokaryotic communities in seagrass bed sediments

    EPA Science Inventory

    Sulfate-reducing prokaryotes (SRP) play a key role in the carbon and nutrient cycles of coastal marine, vegetated ecosystems, but the interactions of SRP communities with aquatic plants remain little studied. The abundance, activity, and community composition of SRP was studied i...

  10. An empirical conceptual gully evolution model for channelled sea cliffs

    NASA Astrophysics Data System (ADS)

    Leyland, Julian; Darby, Stephen E.

    2008-12-01

    Incised coastal channels are a specific form of incised channel that are found in locations where stream channels flowing to cliffed coasts have the excess energy required to cut down through the cliff to reach the outlet water body. The southern coast of the Isle of Wight, southern England, comprises soft cliffs that vary in height between 15 and 100 m and which are retreating at rates ≤ 1.5 m a - 1 , due to a combination of wave erosion and landslides. In several locations, river channels have cut through the cliffs to create deeply (≤ 45 m) incised gullies, known locally as 'Chines'. The Chines are unusual in that their formation is associated with dynamic shoreline encroachment during a period of rising sea-level, whereas existing models of incised channel evolution emphasise the significance of base level lowering. This paper develops a conceptual model of Chine evolution by applying space for time substitution methods using empirical data gathered from Chine channel surveys and remotely sensed data. The model identifies a sequence of evolutionary stages, which are classified based on a suite of morphometric indices and associated processes. The extent to which individual Chines are in a state of growth or decay is estimated by determining the relative rates of shoreline retreat and knickpoint recession, the former via analysis of historical aerial images and the latter through the use of a stream power erosion model.

  11. Evaluation of an integrated sponge--granular activated carbon fluidized bed bioreactor for treating primary treated sewage effluent.

    PubMed

    Xing, W; Ngo, H H; Guo, W S; Listowski, A; Cullum, P

    2011-05-01

    An integrated fluidized bed bioreactor (iFBBR) was designed to incorporate an aerobic sponge FBBR (ASB-FBBR) into an anoxic granular activated carbon FBBR (GAC-FBBR). This iFBBR was operated with and without adding a new starch based flocculant (NSBF) to treat synthetic primary treated sewage effluent (PTSE). The NSBF contains starch based cationic flocculants and trace nutrients. The results indicate that the iFBBR with NSBF addition could remove more than 93% dissolved organic carbon (DOC), 61% total nitrogen (T-N) and 60% total phosphorus (T-P) at just a very short hydraulic retention time of 50 min. The optimum frequency of adding NSBF to the iFFBR is four times per day. As a pretreatment to microfiltration, the iFFBR could increase 5L/m(2)h of critical flux thus reducing the membrane fouling. In addition, better microbial activity was also observed with high DO consumption (>66%) and specific oxygen uptake rate (>35 mg O(2)/g VSS h).

  12. Discrete element modeling of the mass movement and loose material supplying the gully process of a debris avalanche in the Bayi Gully, Southwest China

    NASA Astrophysics Data System (ADS)

    Zhou, Jia-wen; Huang, Kang-xin; Shi, Chong; Hao, Ming-hui; Guo, Chao-xu

    2015-03-01

    The dynamic process of a debris avalanche in mountainous areas is influenced by the landslide volume, topographical conditions, mass-material composition, mechanical properties and other factors. A good understanding of the mass movement and loose material supplying the gully process is very important for understanding the dynamic properties of debris avalanches. Three-dimensional particle flow code (PFC3D) was used to simulate a debris avalanche in Quaternary deposits at the Bayi Gully, Southwest China. FORTRAN and AutoCAD were used for the secondary development to display the mass movement process and to quantitatively describe the mass movement and loose material supplying the gully process. The simulated results show that after the landslide is initiated, the gravitational potential energy is converted into kinetic energy with a variation velocity for the sliding masses. Two stages exist for the average-movement velocity: the acceleration stage and the slowdown stage, which are influenced by the topographical conditions. For the loose materials supplying the gully process, the cumulative volume of the sliding masses into the gully gradually increases over the time. When the landslide volume is not large enough, the increasing landslide volume does not obviously influence the movement process of the sliding masses. The travel distance and movement velocity increase with the decreasing numerical parameters, and the mass-movement process is finished more quickly using low-value parameters. The deposition area of the sliding masses decreases with the increasing numerical parameters and the corresponding deposition thickness increases. The mass movement of the debris avalanche is not only influenced by the mechanical parameters but is also controlled by the topographical conditions.

  13. GIS-analysis of gully erosion susceptibility: a key study in north-central Sicily, Italy

    NASA Astrophysics Data System (ADS)

    Agnesi, Valerio; Angileri, Silvia; Cappadonia, Chiara; Conoscenti, Christian; Costanzo, Dario; Maerker, Michael; Rotigliano, Edoardo

    2010-05-01

    Erosion by water is responsible for severe geo-environmental problems in semi-humid to arid Mediterranean areas. Large sectors of Sicily are affected by intense soil erosion phenomena leading to severe damages in agriculture lands that, in some cases, experience high soil loss rates. An important contribution to sediment yield from these areas is given by gully erosion phenomena; the latter, in the last decades, attracted attention of many researches that developed and applied methods to quantify soil loss volumes and to evaluate proneness of territory to this process. The present research aims to assess gully erosion susceptibility in the basin of the San Giorgio torrent, a mountain stream flowing in north-central Sicily and draining an area of about 9.5 km2; the watershed, which is mainly covered by arable lands, has highly erodible slopes characterized by the outcropping of clays and marls. In order to predict gully erosion susceptibility, a multivariate geostatistical approach is adopted here. In particular, the method is based on the definition of spatial relationships between the geographical variability of a set of controlling factors and the occurrence of gullies on slopes; the linear density of gullies computed on homogeneous domains is selected as the probabilistic function expressing how proneness to gully erosion spatially changes in the studied area. Available thematic maps, which were integrated by field and remote surveys, and a high quality DEM, were used to derive eight layers of terrain variables, selected according to geomorphological criteria and expressing both soil erodibility (bedrock lithology, land use) and erosivity of flowing waters (slope angle, Stream Power Index, SL-factor, Topographic Wetness Index, plan and profile curvature). All the parameters were computed for homogeneous spatial domains, created by intersecting a grid of 50m square polygons and a layer of slope units automatically derived from DEM; therefore, the eight layers

  14. Geomorphology and groundwater origin of amphitheater-shaped gullies at Fort Gordon, Georgia, 2010-2012

    USGS Publications Warehouse

    Landmeyer, James E.; Wellborn, John B.

    2013-01-01

    Seven amphitheater-shaped gullies at valley heads in the northern part of Fort Gordon, Georgia, were identified by personnel from Fort Gordon and the U.S. Geological Survey during a field investigation of environmental contamination near the cantonment area between 2008 and 2010. Between 2010 and 2012, the amphitheater-shaped gullies were photographed, topographic features were surveyed using a global positioning system device, and the extent of erosion was estimated using Light Detection and Ranging imagery. The seven gullies are distributed across a broad area (and most likely are not the only examples) and have a similar geomorphology that includes (1) an amphitheater (semicircular) shaped escarpment at the upgradient end on a plateau of Upper Eocene sands of no readily discernible elevated catchment area or natural surface-water drainage; (2) a narrow, trench-shaped, flat-bottomed incisement of low-permeability marl at the downgradient end; and (3) steep-sided valley walls, some formed by landslides. Surface-water runoff is an unlikely cause for the amphitheater-shaped gullies, because each valley has a relatively small drainage area of sandy terrain even at those gullies that have recently received discharge from stormwater drains. Also, presumed high rates of runoff and gully formation associated with historic land uses, such as clearcutting, cotton production, and silviculture, would have occurred no later than when the fort was established in the early 1900s. The lack of an elevated catchment area at the headward scarps, the amphitheater shape, and presence of low permeability marl at the base of each feature provides the most convincing lines of evidence for headward erosion by groundwater sapping. The absence of current (2013) seeps and springs at most of the amphitheater-shaped gullies indicates that the gullies may have been formed previously by groundwater sapping under conditions of higher and (or) sustained precipitation amounts, local water

  15. Upgrade of deep bed filtration with activated carbon dosage for compact micropollutant removal from wastewater in technical scale.

    PubMed

    Löwenberg, Jonas; Zenker, Armin; Krahnstöver, Thérèse; Boehler, Marc; Baggenstos, Martin; Koch, Gerhard; Wintgens, Thomas

    2016-05-01

    The removal of micropollutants from drinking and wastewater by powdered activated carbon (PAC) adsorption has received considerable attention in research over the past decade with various separation options having been investigated. With Switzerland as the first country in the world having adopted a new legislation, which forces about 100 wastewater treatment plants to be upgraded for the removal of organic micropollutants from municipal wastewater, the topic has reached practical relevance. In this study, the process combination of powdered activated carbon (PAC) adsorption and deep bed filtration (DBF) for advanced municipal wastewater treatment was investigated over an extended period exceeding one year of operation in technical scale. The study aimed to determine optimum process conditions to achieve sufficient micropollutant removal in agreement with the new Swiss Water Ordinance under most economic process design. It was shown that the addition of PAC and Fe(3+) as combined coagulation and flocculation agent improved effluent water quality with respect to dissolved organic pollutants as well as total suspended solids (TSS), turbidity and PO4-P concentration in comparison to a DBF operated without the addition of PAC and Fe(3+). Sufficient micropollutant (MP) removal of around 80% was achieved at PAC dosages of 10 mg/L revealing that PAC retained in the filter bed maintained considerable adsorption capacity. In the investigated process combination the contact reactor serves for adsorption as well as for flocculation and allowed for small hydraulic retention times of minimum 10 min while maintaining sufficient MP removal. The flocculation of two different PAC types was shown to be fully concluded after 10-15 min, which determined the flocculation reactor size while both PAC types proved suitable for the application in combination with DBF and showed no significant differences in MP removal. Finally, the capping of PAC dosage during rain water periods, which

  16. The Impact of Ozone Treatment in Dynamic Bed Parameters on Changes in Biologically Active Substances of Juniper Berries

    PubMed Central

    Brodowska, Agnieszka Joanna; Śmigielski, Krzysztof; Nowak, Agnieszka; Czyżowska, Agata; Otlewska, Anna

    2015-01-01

    The development of the parameters of ozone decontamination method assuring the least possible losses of biologically active substances (essential oils and polyphenols) and their activity in common juniper (Juniperus communis (L.)) berries was studied. Ozone treatment in dynamic bed was conducted 9 times. The process was conducted under different ozone concentrations (100.0; 130.0; 160.0 g O3/m3) and times (30, 60, 90 min). After each decontamination, the microbiological profile of the juniper berries was studied, and the contaminating microflora was identified. Next to the microbiological profile, the phenolic profile, as well as antioxidant activity of extracts and essential oils were determined. The total polyphenol content (TPC), composition of essential oils, free radical-scavenging capacity, total antioxidant capacity, ferric-reducing antioxidant power (FRAP), beta-carotene bleaching test (BCB) and LC-MS polyphenol analysis were carried out. The study reveals that during short ozone contact times, higher amounts of TPC, 15.47 and 12.91 mg CE/g of extract, for samples 100/30 and 130/30, respectively, were demonstrated. Whereas samples 100/60, 130/60, 100/90, and 160/90 exhibited the lowest amount of phenolics. The highest antioxidant activity was found in the methanol extract obtained from ozonated berries which exhibited the lowest IC50 in all the antioxidant assays, such as DPPH, FRAP, and BCB assays. Ozone treatment showed noteworthy potential and its usage in food manufacturing and as an alternative decontamination method should be considered. PMID:26659905

  17. Field Studies of Gullies and Pingos on Svalbard - a Martian Analog.

    NASA Astrophysics Data System (ADS)

    Carlsson, E.; Johannsson, H. A. B.; Johnsson, A.; Heldmann, J. L.; McKay, C. P.; Olvmo, M.; Johansson, L.; Fredriksson, S.; Schmidt, H. T.; McDaniel, S.; Reiss, D.; Hiesinger, H.; Hauber, E.; Zanetti, M.

    2008-09-01

    Introduction: The gully systems on Mars [1] have been found to superpose young geological surfaces such as dunes and thermal contraction polygons [2]. This in combination with the general absence of superimposed impact craters suggest that the gullies are relatively recent geological formations [3]. The observed gullies display a wide set of morphologies ranging from features seemingly formed by fluvial erosion to others pointing to dry landslide processes. A recent discovery [4] suggests that this is an ongoing process, which appears to occur even today. Several formation mechanisms have been proposed for the Martian gullies, such as liquid carbon dioxide reservoirs [5], shallow liquid water aquifer [6], melting ground ice [7], dry landslide [8], snow melt [9] and deep liquid water aquifer [10]. However, none of these models can alone explain all the gullies discovered on Mars. So far Martian gullies have been studied only from orbit via remote sensing data. Hydrostatic pingos are perennial ice-cored mounds that may reach an elongated or circular radius of approximately 150 m. They are found in periglacial environments where they are formed by freezing processes in the continuous permafrost. The pingos go through different evolutionary stages as they mature, where the final stage leaves an annular rim left by the collapse of the summit. Images from the High Resolution Imaging Science Experiment (HiRISE) show small fractured mounds in the Martian mid-latitudes [11]. Even though some differences are observed, the best terrestrial analogues for the observed mound morphology are pingos [11]. Gullies and pingos found in Arctic climates on Earth could be an analog for the Martian ones. A comparative analysis might help to understand the formation mechanisms of the Martian pingos and gullies and their possible eroding agent. Svalbard as a Martian Analog: Svalbard is situated at 74°-81°N and 10°-35°E, in the discontinuous zone of permafrost, and is a fairly good

  18. Episodic bedrock erosion by gully-head migration, Colorado High Plains, USA

    USGS Publications Warehouse

    Rengers, Francis; Tucker, G.E.; Mahan, Shannon

    2016-01-01

    This study explores the frequency of bedrock exposure in a soil-mantled low-relief (i.e. non-mountainous) landscape. In the High Plains of eastern Colorado, gully headcuts are among the few erosional features that will incise through the soil mantle to expose bedrock. We measured the last time of bedrock exposure using optically stimulated luminescence dating of alluvial sediment overlying bedrock in gully headcuts. Our dating suggests that headcuts in adjacent gullies expose bedrock asynchronously, and therefore, the headcuts are unlikely to have been triggered by a base-level drop in the trunk stream. This finding supports the hypothesis that headcuts can develop locally in gullies as a result of focused scour in locations where hydraulic stress during a flash flood is sufficiently high, and/or ground cover is sufficiently weak, to generate a scour hole that undermines vegetation. Alluvium dating also reveals that gullies have been a persistent part of this landscape since the early Holocene. 

  19. Field Studies of Gullies and Pingos on Svalbard - a Martian Analog.

    NASA Astrophysics Data System (ADS)

    Carlsson, E.; Johannsson, H. A. B.; Johnsson, A.; Heldmann, J. L.; McKay, C. P.; Olvmo, M.; Johansson, L.; Fredriksson, S.; Schmidt, H. T.; McDaniel, S.; Reiss, D.; Hiesinger, H.; Hauber, E.; Zanetti, M.

    2008-09-01

    Introduction: The gully systems on Mars [1] have been found to superpose young geological surfaces such as dunes and thermal contraction polygons [2]. This in combination with the general absence of superimposed impact craters suggest that the gullies are relatively recent geological formations [3]. The observed gullies display a wide set of morphologies ranging from features seemingly formed by fluvial erosion to others pointing to dry landslide processes. A recent discovery [4] suggests that this is an ongoing process, which appears to occur even today. Several formation mechanisms have been proposed for the Martian gullies, such as liquid carbon dioxide reservoirs [5], shallow liquid water aquifer [6], melting ground ice [7], dry landslide [8], snow melt [9] and deep liquid water aquifer [10]. However, none of these models can alone explain all the gullies discovered on Mars. So far Martian gullies have been studied only from orbit via remote sensing data. Hydrostatic pingos are perennial ice-cored mounds that may reach an elongated or circular radius of approximately 150 m. They are found in periglacial environments where they are formed by freezing processes in the continuous permafrost. The pingos go through different evolutionary stages as they mature, where the final stage leaves an annular rim left by the collapse of the summit. Images from the High Resolution Imaging Science Experiment (HiRISE) show small fractured mounds in the Martian mid-latitudes [11]. Even though some differences are observed, the best terrestrial analogues for the observed mound morphology are pingos [11]. Gullies and pingos found in Arctic climates on Earth could be an analog for the Martian ones. A comparative analysis might help to understand the formation mechanisms of the Martian pingos and gullies and their possible eroding agent. Svalbard as a Martian Analog: Svalbard is situated at 74°-81°N and 10°-35°E, in the discontinuous zone of permafrost, and is a fairly good

  20. Mutual interactions of Pleurotus ostreatus with bacteria of activated sludge in solid-bed bioreactors.

    PubMed

    Svobodová, Kateřina; Petráčková, Denisa; Kozická, Barbora; Halada, Petr; Novotný, Čeněk

    2016-06-01

    White rot fungi are well known for their ability to degrade xenobiotics in pure cultures but few studies focus on their performance under bacterial stress in real wastewaters. This study investigated mutual interactions in co-cultures of Pleurotus ostreatus and activated sludge microbes in batch reactors and different culture media. Under the bacterial stress an increase in the dye decolorization efficiency (95 vs. 77.1 %) and a 2-fold elevated laccase activity (156.7 vs. 78.4 Ul(-1)) were observed in fungal-bacterial cultures compared to pure P. ostreatus despite a limited growth of bacteria in mixed cultures. According to 16S-rDNA analyses, P. ostreatus was able to alter the structure of bacterial communities. In malt extract-glucose medium the fungus inhibited growth of planktonic bacteria and prevented shifts in bacterial utilization of potential C-sources. A model bacterium, Rhodococcus erythropolis responded to fungal metabolites by down regulation of uridylate kinase and acetyl-CoA synthetase. PMID:27116960

  1. [Dynamic changes of Robinia pseudoacacia sap flow in hilly-gully region of Loess Plateau].

    PubMed

    Hu, Wei; Du, Feng; Xu, Xue-Xuan; Zhang, Liang-De

    2010-06-01

    From April 14 to October 10, 2009, the dynamic changes of Robinia pseudoacacia sap flow in the hilly-gully region of Loess Plateau were measured with thermal dissipation probe. Meantime, the photosynthetic active radiation (PAR), air temperature, relative air humidity, water vapor pressure deficit (VPD), wind speed, and rainfall were monitored. The diurnal variation of the sap flow velocity (SFV) displayed a single-peak curve, but the pattern varied among different months. In April, the sap flow started to increase at about 12:00, and reached the peak at about 18:00. From May to August, the sap flow started to increase at 5:30-7:30, and reached the peak at about 15:00. In September and October, the sap flow started to increase at about 8:00, and reached the peak at 11:30-13:00. The monthly average SFV was the highest in August and the lowest in April, with the value being 0.002610 cm x s(-1) and 0.000549 cm x s(-1), respectively. During the monitoring period, the sap flow velocity was significantly correlated with PAR, air temperature, VPD, wind speed, and air relative humidity, and the correlation coefficients declined in the order of air temperature > VPD > PAR > relative humidity > wind speed. The sap flow velocity could be estimated by the linear equation with variables PAR and VPD, and the regression coefficients were highly significant.

  2. The Local Complement Activation on Vascular Bed of Patients with Systemic Sclerosis: A Hypothesis-Generating Study

    PubMed Central

    Scambi, Cinzia; Ugolini, Sara; Jokiranta, T. Sakari; De Franceschi, Lucia; Bortolami, Oscar; La Verde, Valentina; Guarini, Patrizia; Caramaschi, Paola; Ravagnani, Viviana; Martignoni, Guido; Colato, Chiara; Pedron, Serena; Benedetti, Fabio; Sorio, Marco; Poli, Fabio; Biasi, Domenico

    2015-01-01

    Objective The role of complement system in the pathogenesis of systemic sclerosis (SSc) has been debated during the last decade but an evident implication in this disease has never been found. We carried out an explorative study on SSc patients to evaluate the expression of soluble and local C5b-9 complement complex and its relation with a complement regulator, the Membrane Cofactor Protein (MCP, CD46) on skin vascular bed as target distinctive of SSc disease. We also analyzed two polymorphic variants in the complement activation gene cluster involving the MCP region. Methods C5b-9 plasma levels of SSc patients and healthy subjects were analyzed by ELISA assay. Archival skin biopsies of SSc patients and controls were subjected to immunofluorescence analysis to detect C5b-9 and MCP on vascular endothelial cells. The expression of MCP was validated by immunoblot analysis with specific antibody. Polymorphic variants in the MCP gene promoter were tested by a quantitative PCR technique-based allelic discrimination method. Results Even though circulating levels of C5b-9 did not differ between SSc and controls, C5b-9 deposition was detected in skin biopsies of SSc patients but not in healthy subjects. MCP was significantly lower in skin vessels of SSc patients than in healthy controls and was associated with the over-expression of two polymorphic variants in the MCP gene promoter, which has been related to more aggressive phenotypes in other immune-mediated diseases. Conclusions Our results firsty document the local complement activation with an abnormal expression of MCP in skin vessels of SSc patients, suggesting that a subset of SSc patients might be exposed to more severe organ complications and clinical evolution due to abnormal local complement activation. PMID:25658605

  3. 75 FR 1723 - Fisheries of the Exclusive Economic Zone Off Alaska; Chiniak Gully Research Area for Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-13

    ... Economic Zone Off Alaska; Chiniak Gully Research Area for Vessels Using Trawl Gear AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Temporary rule. SUMMARY: NMFS is rescinding the trawl closure in the Chiniak Gully Research Area....

  4. Recovery comparisons--hot nitrogen Vs steam regeneration of toxic dichloromethane from activated carbon beds in oil sands process.

    PubMed

    Ramalingam, Shivaji G; Pré, Pascaline; Giraudet, Sylvain; Le Coq, Laurence; Le Cloirec, Pierre; Baudouin, Olivier; Déchelotte, Stéphane

    2012-02-29

    The regeneration experiments of dichloromethane from activated carbon bed had been carried out by both hot nitrogen and steam to evaluate the regeneration performance and the operating cost of the regeneration step. Factorial Experimental Design (FED) tool had been implemented to optimize the temperature of nitrogen and the superficial velocity of the nitrogen to achieve maximum regeneration at an optimized operating cost. All the experimental results of adsorption step, hot nitrogen and steam regeneration step had been validated by the simulation model PROSIM. The average error percentage between the simulation and experiment based on the mass of adsorption of dichloromethane was 2.6%. The average error percentages between the simulations and experiments based on the mass of dichloromethane regenerated by nitrogen regeneration and steam regeneration were 3 and 12%, respectively. From the experiments, it had been shown that both the hot nitrogen and steam regeneration had regenerated 84% of dichloromethane. But the choice of hot nitrogen or steam regeneration depends on the regeneration time, operating costs, and purity of dichloromethane regenerated. A thorough investigation had been made about the advantages and limitations of both the hot nitrogen and steam regeneration of dichloromethane.

  5. A compact process for treating oilfield wastewater by combining hydrolysis acidification, moving bed biofilm, ozonation and biologically activated carbon techniques.

    PubMed

    Zheng, Tao

    2016-01-01

    A lab-scale hybrid system integrating a hybrid hydrolysis acidification (HA) reactor, a moving bed biofilm reactor (MBBR) and an ozonation-biologically activated carbon (O3-BAC) unit was used in the treatment of heavy oil wastewater with high chemical oxygen demand (COD) and low biodegradability. The effects of hydraulic retention time and ozonation time were investigated. The results show that under the optimal conditions, the effluent concentrations of COD, oil and ammonia were 48, 1.3 and 3.5 mg/L, respectively, corresponding to total removal efficiencies of 95.8%, 98.9% and 94.4%, respectively. The effluent could meet the grade I as required by the national discharge standard of China. The HA process remarkably improved the biodegradability of the wastewater, while the MBBR process played an important role in degrading COD. The ozonation process further enhanced the biodegradability of the MBBR effluent, and finally, deep treatment was completed in the BAC reactor. This work demonstrates that the hybrid HA/MBBR/O3-BAC system has the potential to be used for the treatment of high-strength oilfield wastewater.

  6. Coalesced chitosan activated carbon composite for batch and fixed-bed adsorption of cationic and anionic dyes.

    PubMed

    Auta, M; Hameed, B H

    2013-05-01

    A renewable waste tea activated carbon (WTAC) was coalesced with chitosan to form composite adsorbent used for waste water treatment. Adsorptive capacities of crosslinked chitosan beads (CCB) and its composite (WTAC-CCB) for Methylene blue dye (MB) and Acid blue 29 (AB29) were evaluated through batch and fixed-bed studies. Langmuir, Freundlich and Temkin adsorption isotherms were tested for the adsorption process and the experimental data were best fitted by Langmuir model and least by Freundlich model; the suitability of fitness was adjudged by the Chi-square (χ(2)) and Marquadt's percent standard deviation error functions. Judging by the values of χ(2), pseudo-second-order reaction model best described the adsorption process than pseudo-first-order kinetic model for MB/AB29 on both adsorbents. After five cycles of adsorbents desorption test, more than 50% WTAC-CCB adsorption efficiency was retained while CCB had <20% adsorption efficiency. The results of this study revealed that WTAC-CCB composite is a promising adsorbent for treatment of anionic and cationic dyes in effluent wastewaters.

  7. Adsorption and desorption of noble gases on activated charcoal: I. 133Xe studies in a monolayer and packed bed.

    PubMed

    Scarpitta, S C; Harley, N H

    1990-10-01

    Detailed desorption studies using petroleum-based activated charcoals were conducted in monolayers and packed beds. Less extensive studies were conducted on several other types of charcoal. Kinetic studies, using 133Xe, demonstrated the existence of a micropore volume with entrance capillaries that together determined the response characteristics of charcoal to external concentration gradients of tracer gases. This new two-phase model, composed of micropores and entrance capillaries, describes the desorption dynamics of an adsorbed gas in the presence of water vapor. Condensed water vapor in the entrance capillaries of the charcoal reduced the effective pore radius and increased the diffusion half-time. Water could also adversely affect the integrating capability of the charcoal dramatically if the adsorbed water completely blocked the entrance capillaries. The amount of adsorbed water required to block the capillaries varied with the charcoal type and was termed here as the "break-point." The desorption parameters measured in this work can be used to design an improved passive Rn monitor to effectively integrate during a 3-7 d exposure period by eliminating the adverse effects of water vapor. The improved canister design would provide more accurate and reproducible measurements of indoor Rn concentrations than are currently available. PMID:2398007

  8. Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions

    NASA Technical Reports Server (NTRS)

    Heldmann, J. L.; Toon, O. B.; Pollard, W. H.; Mellon, M. T.; Pitlick, J.; McKay, C. P.; Andersen, D. T.

    2005-01-01

    Images from the Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft show geologically young small-scale features resembling terrestrial water-carved gullies. An improved understanding of these features has the potential to reveal important information about the hydrological system on Mars, which is of general interest to the planetary science community as well as the field of astrobiology and the search for life on Mars. The young geologic age of these gullies is often thought to be a paradox because liquid water is unstable at the Martian surface. Current temperatures and pressures are generally below the triple point of water (273 K, 6.1 mbar) so that liquid water will spontaneously boil and/or freeze. We therefore examine the flow of water on Mars to determine what conditions are consistent with the observed features of the gullies.

  9. How did the icy mantle of Mars contribute to the origins of gullies and FSVs?

    NASA Astrophysics Data System (ADS)

    Glines, Natalie; Gulick, Virginia C.

    2016-10-01

    Compared to the Martian valley networks, Fresh Shallow Valleys (FSVs) and gullies formed quite recently - in the Late Amazonian period. Recent studies propose that FSVs may be formed by meltwater flowing beneath ice, supported by evidence for the channels ignoring the constraints of drainage divides and often being found with ridges and mounds analogous to terrestrial esker environments. Our studies of gullies show that while multiple processes have contributed to their formation and modification over time, the key sources include groundwater flow, ground ice melt, or ice/snow surface melt, which includes the possibility of meltwater from ice-rich LDM. FSVs and gullies have been found to be spatially associated with viscous flow features (VFFs), mantle deposits, and various peri/paraglacial features such as arcuate ridges. It is important to note that the mid-latitude bands within which the FSVs and gullies concentrate are both near enough to the poles to experience frozen depositions during periods of high obliquity, and near enough to the equator to experience melt induced by peak temperatures, possible today where surface pressure is also favorable. While FSVs and gullies are often found dissecting into mantle deposits, it is possible that the easily-erodible ice-rich LDM simply provides insulation and protective blanketing to promote or enable water flow and ice melt from the near-subsurface. We are looking to identify any changes to channels and ice-rich LDM within FSVs and gullies to help determine whether the water's source is from the ice-rich mantling unit, the subsurface, or both.

  10. Gully head development controlled by land surface management in Lake Tana basin, Ethiopia

    NASA Astrophysics Data System (ADS)

    Monsieurs, Elise; Nyssen, Jan; Dessie, Mekete; Verhoest, Niko E. C.; Deckers, Jozef; Adgo, Enyew; Poesen, Jean

    2015-04-01

    In contrast to level areas where drainage ditches mainly aim at lowering the level of the phreatic surface when it comes near or at the surface, digging ditches to divert runoff water on sloping cropland is a physical soil conservation practice to protect the land from uncontrolled runoff and hence decrease the risk of topsoil and seedling erosion. However, researchers are still divided about the balance of the positive and negative effects which can be both on-site and off-site. A case study area was chosen around Wanzaye (North Ethiopia) where three different cropland-management practices were studied in 75 catchments: (i) the catchment-wide use of stone bunds on the contour, (ii) the use of slightly sloping drainage furrows (feses), and (iii) the combined use of stone bunds and feses. A standardized procedure for topographical threshold analysis was applied to study the impact of different land management practices on gully head development in cropland. Topographical thresholds for gully head development reflect the vulnerability of lands to gullying, i.e. s > kA^-b, where s represents slope gradient of the soil surface, A the drainage area at the gully head, b an exponent, and k the resistance of the land to gully head development. The lowest k-values are found for feses catchments, which implies that catchments with the exclusive use of drainage ditches are the most vulnerable to gully head development compared to mixed catchments and stone bund catchments. Yet, on-site sheet and rill erosion are reduced by the use of feses as they reduce the runoff gradient.

  11. Bright Gully Deposits in Hale Crater and Implications for Recent Water

    NASA Astrophysics Data System (ADS)

    Kolb, K. J.; McEwen, A. S.; Pelletier, J. D.; HiRISE Team

    2007-12-01

    Hale Crater, a late Hesperian / early Amazonian [Cabrol N.A. et al., 2001 Icarus 154] 120 km x 150 km impact crater, hosts a large number of gullies with a variety of orientations. Gully distributions and orientations have strong implications for distinguishing between gully formation theories, which frequently depend on insolation or a local aquifer. Several of the gullies exhibit bright deposits that are unmodified at the scale, 0.26 - 0.31 cm/pixel, of images acquired by the High Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO). Two recently formed bright gully deposits (BGDs) imaged by the Mars Orbiter Camera (MOC) at other locations were initially interpreted as evidence for water on the surface in recent years [Malin M.C. et al., 2006 Science 314]. One of these BGDs was modelled by Pelletier et al. [2007 submitted] who found that, although water could not be ruled out in the formation of the studied BGD, dry flow was sufficient. HiRISE has imaged several other unmodified BGDs around Mars, most of which occur on steep slopes (26-35°) [McEwen A.S. et al., 2007 Science in press] in fresh craters. The slopes of one section of Hale Crater with BGDs are closer to 19-20°, which suggests that it would be difficult for a dry debris flow to form the BGDs. We investigate the distribution and orientations of gullies and BGDs, as well as slope profiles, in Hale Crater. We present results of modeling the BGDs using Mars Orbiter Laser Altimeter (MOLA) topography and available imagery and evaluate the likelihood that the BGDs required or included water in their formation.

  12. Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

    NASA Astrophysics Data System (ADS)

    Nazari Samani, Aliakbar; Chen, Qiuwen; Khalighi, Shahram; Wasson, Robert James; Rahdari, Mohammad Reza

    2016-07-01

    A gully as an accelerated erosion process is responsible for land degradation under various environmental conditions and has been known as a threshold phenomenon. Although the effects of gullying processes have been well documented, few soil erosion models have taken into account the threshold condition necessary for gully development. This research was devoted to determining the effects of land use change on hydraulic threshold condition and stream power of water flow through an in situ experimental flume (15 m × 0.4 m). Results indicated that head cut initiation and detachment rates showed a better correlation to stream power indices than shear stress (τcr). The threshold unit stream power value (ωu) for head cut initiation in rangeland, abandoned land, and dry farming land was 0.0276, 0.0149, and 4.5 × 10-5 m s-1, respectively. Moreover, the micro-relief condition of soil surface and surface vegetation affected the flow regime of discharge and velocity. It is seen that the composite hydraulic criteria of Froude number (Fr) and discharge (Q) can clearly discriminate the land uses' threshold. In fact, the remarkable decrease of τcr in dry farming was related to the effect of tillage practice on soil susceptibility and aggregate strength. The findings indicated that using the unit steam power index instead of critical shear stress could increase the models' precision for prediction of head cut development. Compared to the Ephemeral Gully Erosion Model (EGEM) equation for critical shear stress, it is important to point out that for modelling of gully erosion, using single soil attributes can lead to an inaccurate estimation for τcr. In addition, based on the findings of this research, the use of threshold values of τcr = 35 dyne cm-2 and ωu = 0.4 cm s-1 in physically based soil erosion models is susceptible to high uncertainty when assessing gully erosion.

  13. Bed Bugs FAQs

    MedlinePlus

    ... Tropical Diseases Laboratory Diagnostic Assistance [DPDx] Parasites Home Bed Bugs FAQs Recommend on Facebook Tweet Share Compartir On ... are bed bugs treated and prevented? What are bed bugs? Bed bugs ( Cimex lectularius ) are small, flat, parasitic ...

  14. Treatment bed microbiological control

    NASA Technical Reports Server (NTRS)

    Janauer, Gilbert E.; Fitzpatrick, Timothy W.; Kril, Michael B.; Wilber, Georgia A.; Sauer, Richard L.

    1987-01-01

    The effects of microbial fouling on treatment bed (TB) performance are being studied. Fouling of activated carbon (AC) and ion exchange resins (IEX) by live and devitalized bacteria can cause decreased capacity for selected sorbates with AC and IEX TB. More data are needed on organic species removal in the trace region of solute sorption isotherms. TB colonization was prevented by nonclassical chemical disinfectant compositions (quaternary ammonium resins) applied in suitable configurations. Recently, the protection of carbon beds via direct disinfectant impregnation has shown promise. Effects (of impregnation) upon bed sorption/removal characteristics are to be studied with representative contaminants. The potential need to remove solutes added or produced during water disinfection and/or TB microbiological control must be investigated.

  15. Generalizing a complex model for gully threshold identification in the Mediterranean environment

    NASA Astrophysics Data System (ADS)

    Torri, D.; Borselli, L.; Iaquinta, P.; Iovine, G.; Poesen, J.; Terranova, O.

    2012-04-01

    Among the physical processes leading to land degradation, soil erosion by water is the most important and gully erosion may contribute, at places, to 70% of the total soil loss. Nevertheless, gully erosion has often been neglected in water soil erosion modeling, whilst more prominence has been given to rill and interrill erosion. Both to facilitate the processing by agricultural machinery and to take advantage of all the arable land, gullies are commonly removed at each crop cycle, with significant soil losses due to the repeated excavation of the channel by the successive rainstorm. When the erosive forces of overland flow exceed the strength of the soil particles to detachment and displacement, water erosion occurs and usually a channel is formed. As runoff is proportional to the local catchment area, a relationship between local slope, S, and contributing area, A, is supposed to exists. A "geomorphologic threshold" scheme is therefore suitable to interpret the physical process of gully initiation: accordingly, a gully is formed when a hydraulic threshold for incision exceeds the resistance of the soil particles to detachment and transport. Similarly, it appears reasonable that a gully ends when there is a reduction of slope, or the concentrated flow meets more resistant soil-vegetation complexes. This study aims to predict the location of the beginning of gullies in the Mediterranean environment, based on an evaluation of S and A by means of a mathematical model. For the identification of the areas prone to gully erosion, the model employs two empirical thresholds relevant to the head (Thead) and to the end (Tend) of the gullies (of the type SA^ b>Thead, SA^ bgully erosion, depending on: stoniness, vegetation cover, propensity to tunneling erosion due to soil dispersibility in water, and the intrinsic characteristics of the eroded material and of the erosivity of the rainfall event. Such

  16. RADIOACTIVE DEMONSTRATIONS OF FLUIDIZED BED STEAM REFORMING WITH ACUTAL HANFORD LOW ACTIVITY WASTES VERIFYING FBSR AS A SUPPLEMENTARY TREATMENT

    SciTech Connect

    Jantzen, C.; Crawford, C.; Burket, P.; Bannochie, C.; Daniel, G.; Nash, C.; Cozzi, A.; Herman, C.

    2012-01-12

    The U.S. Department of Energy's Office of River Protection is responsible for the retrieval, treatment, immobilization, and disposal of Hanford's tank waste. Currently there are approximately 56 million gallons of highly radioactive mixed wastes awaiting treatment. A key aspect of the River Protection Project cleanup mission is to construct and operate the Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level waste (HLW) and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the cleanup mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA). Therefore, Supplemental Treatment is required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. Fluidized Bed Steam Reforming (FBSR) is one of the supplementary treatments being considered. FBSR offers a moderate temperature (700-750 C) continuous method by which LAW and other secondary wastes can be processed irrespective of whether they contain organics, nitrates/nitrites, sulfates/sulfides, chlorides, fluorides, and/or radio-nuclides like I-129 and Tc-99. Radioactive testing of Savannah River LAW (Tank 50) shimmed to resemble Hanford LAW and actual Hanford LAW (SX-105 and AN-103) have produced a ceramic (mineral) waste form which is the same as the non-radioactive waste simulants tested at the engineering scale. The radioactive testing demonstrated that the FBSR process can retain the volatile radioactive components that cannot be contained at vitrification temperatures. The radioactive and nonradioactive mineral waste forms that were produced by co-processing waste with kaolin clay in an FBSR process are shown to be as durable as LAW glass.

  17. Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

    PubMed

    Rahman, N K; Kamaruddin, A H; Uzir, M H

    2011-08-01

    The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

  18. Application of the biological granular activated carbon fluidized bed reactor process for gas industry waste treatment. Topical report, January 1991-December 1992

    SciTech Connect

    Wagner, D.; Sunday, A.; Hickey, R.F.

    1993-06-01

    The research and development work is focused on evaluating the applicability of using the biological granular activated carbon-fluidized bed reactor (GAC-FBR) for helping to solve gas industry waste treatment needs. The specific goals are to use and modify the GAC-FBR process, as needed, for (1) remediation of groundwater contaminated by gas industry operations, and (2) treatment of gas production and exploration waters.

  19. A regression model for the temporal development of soil pipes and associated gullies in the alluvial-fill valley of the Rio Puerco, central New Mexico

    NASA Astrophysics Data System (ADS)

    Condit, C. D.; Elston, W. E.

    1984-04-01

    On Mars, the association of gullied escarpments and chaotic terrain is evidence for failure and scarp retreat of poorly consolidated materials. Some martian gullies have no surface outlets and may have drained through subterranean channels. Similar features, though on a much smaller scale, can be seen in alluvium along terrestrial river banks in semiarid regions, such as the Rio Puerco Valley of central New Mexico. Many of the escarpments along the Rio Puerco are developing through formation of collapse gullies, which drain through soil pipes. Gully development can be monitored on aerial photographs taken in 1935, 1962, and 1980. A regression model was developed to quantify gully evolution over a known time span. Soil pipes and their associated collapse gullies make recognizable signatures on the air photos. The areal extent of this signature can be normalized to the scarp length of each pipe-gully system, which makes comparisons between systems possible.

  20. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  1. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  2. Assessing gully widening and its control in the Debri-Mawi Watershed, northern Ethiopia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The highlands of northern Ethiopia suffer from severe land degradation manifested by widespread gully and channel erosion and network development. Research on the geomorphic adjustment of similar landscapes in the midcontinental United States has resulted in the development of the computer models BS...

  3. Preliminary gully assessment using photo-reconstruction from own-manufactured UAV images

    NASA Astrophysics Data System (ADS)

    Ruano-Castro, Vicente; Castillo, Carlos; Gomez, Jose A.; Perez, Rafael

    2014-05-01

    Unmanned Aerial Vehicles (UAV) are becoming increasingly useful in several professional and research fields, among other, in geomorphology applications. UAV helicopters (with one or more rotors) present some advantages compared to fixed wing drones such as the possibility of stationary fly. On the other hand, 3D-photoreconstruction has been successfully applied for gully assessment at the reach scale. The combination of both approaches can result in a substantial reduction of time requirements at the gully network scale. The purpose of this communication is to describe the construction of an UAV with carbor-fiber frame and its fitting for capturing air images. Routes controlled by GPS were programmed in advance using Google Earth. Although an improved design with 8 rotors is in progress, currently the design is equipped with 4 rotors. This new design will allow the use of heavier and more precise cameras. In addition, the isolation of the inner electronic equipment will increase the possibility of use in bad weather. The images obtained by the UAV were processed using 3D-photoreconstruction to derive a digital elevation model of a several-hundred meters gully. References Castillo, C., R. Perez, M.R. James, J.N. Quinton, E.V. Taguas, J.A. Gómez. 2012. Comparing the Accuracy of Several Field Methods for Measuring Gully Erosion. Soil Science Society of America Journal 76: 1319-1332.

  4. Internal erosion during soil pipe flow: Role in gully erosion and hillslope instability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many field observations have lead to speculation on the role of piping in embankment failures, landslides, and gully erosion. However, there has not been a consensus on the subsurface flow and erosion processes involved and inconsistent use of terms have exasperated the problem. One such piping proc...

  5. The Role of Preferential Flow Through Soil-Pipes on Ephemeral Gully Erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimates by the USDA for 17 States suggest that ephemeral gully erosion ranges from 18 to 73% of the total erosion with a median of 35%. Concentrated flow is generally considered the controlling process and subsurface flow is often overlooked. Pipe-erosion may occur with no visible evidence until p...

  6. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion.

    PubMed

    Fox, G A; Sheshukov, A; Cruse, R; Kolar, R L; Guertault, L; Gesch, K R; Dutnell, R C

    2016-05-01

    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

  7. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion.

    PubMed

    Fox, G A; Sheshukov, A; Cruse, R; Kolar, R L; Guertault, L; Gesch, K R; Dutnell, R C

    2016-05-01

    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds. PMID:26885658

  8. Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

    NASA Astrophysics Data System (ADS)

    Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.

    2016-05-01

    The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

  9. Evaluating ephemeral gully erosion impact on Zea mays L. yield and economics using AnnAGNPS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ephemeral gully erosion causes serious water quality and economic problems in the Midwest United States. A critical barrier to soil conservation practice adoption is often the implementation cost, although it is recognized that erosion reduces farm income. Yet few, if any, understand the relationshi...

  10. Characterization of the hydraulic performance of a gully under drainage conditions.

    PubMed

    Martins, Ricardo; Leandro, Jorge; de Carvalho, Rita Fernandes

    2014-01-01

    During rainfall events with low return periods (1-20 years) the drainage system can provide some degree of protection to urban areas. The system design is based not only on good hydraulic performance of the surface and the sewer network but also on their linking elements. Although the linking elements are of utmost importance as they allow the exchange of flow between the surface and the sewer network, there is a lack of studies that thoroughly characterize them. One crucial structural part of those elements is the gully. State-of-the-art dual-drainage models often use simplified formulae to replicate the gully hydraulic behaviour that lacks proper validation. This work focuses on simulating, both numerically and experimentally, the hydraulic performance of a 0.6 × 0.3 × 0.3 [m] (L × W × D) gully located inside an 8 × 0.5 × 0.5 [m] rectangular channel. The numerical simulations are conducted with the OpenFOAM toolbox and validated with water level measurements in the Multiple-Linking-Element experimental installation located at the Laboratory of Hydraulics of the University of Coimbra. The results provide a complete three-dimensional insight of the hydraulic behaviour of the flow inside the gully, and discharge coefficient formulae are disclosed that can be directly applied in dual-drainage models as internal boundary conditions. PMID:24960003

  11. Assessment of the Compound Topographic Index CTI to predict Potential Ephemeral Gullies in Navarre (Spain)

    NASA Astrophysics Data System (ADS)

    Chahor, Y.; Casalí, J.; Giménez, R.

    2012-04-01

    Ephemeral gullies are relatively small (susceptible of being obliterated by conventional tillage operation) eroded channels that are able to generate however important in-site and off-site damages (removal of top soil and nutrients, degradation of drinking water quality, contamination of aquatic ecosystems, siltation, etc.). Gully initiation and development in a watershed is greatly driven by topographic factors. Precisely, several topographic indexes have been used to identify areas with risk of gully erosion. Among them, the Compound Topographic Index (CTI= A.S.PLANC; A: upstream drainage area, S: local slope, PLANC: planform curvature) is an approach recently implemented in the AnnAGNPS (Annualized Agricultural Nonpoint Source Pollution) model. It allows defining the location of potential ephemeral gullies (PEG). The aim of this work was to assess the capability of CTI for predicting PEG mouths (potential headcut) location in an agricultural field of Navarre (Spain) through AnnAGNPS. The study was carried out in a 450 ha area cultivated with wheat and located in Pitillas (southern Navarre). The climate is continental Mediterranean with a mean temperature of 13°C and annual rainfall of 500 mm. Top soil textures are mostly loamy and silt-loam. The 3 topographic components of the CTI were computed by TOPAZ program implemented in AnnAGNPS 5.10 using a digital elevation model of 5-m resolution. The CTI is computed for each raster grid. Then all the values are arranged from the smallest to the largest and then percentiles are calculated (for example, the 95th percentile is the threshold CTI value below which 95% of the CTI values may be found). Grid cells whose values correspond to a percentile lower than 90% are discarded by the model by default. On the other hand, 31 ephemeral gullies located within the studied agricultural field were selected from orthophotos (1:5,000). Natural drainage channels located in abandoned, steep pieces of terrain were not considered in

  12. Cost analysis of gully restoration in agricultural areas in Andalusia (Spain)

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Taguas, Encarnación; Mora, Jose; Gómez, Jose Alfonso

    2013-04-01

    Cost optimization of soil conservation measures is essential in the agricultural sector where the farmers return of investment is usually small, and there is a high degree of uncertainty about yield. The main aims of this study are: 1) to assess the cost of check dams and revegetation measures for a wide range of situations on gully networks of Andalusia and 2) provide an estimation of the adequate budget requirements for the gully restoration at farms included in the public Incentive Program for Gully Control (IPGC) supported by the Junta de Andalucia (Spain). Firstly, a study was conducted to design the structures adapted to a wide variety of gully conditions (slope, width, height, unitary discharge) in the region of Andalusia, and check dam materials (concrete and gabions) taking into account conventional engineering stability criteria, recommendations in technical literature (Gómez et al., 2011) and principles of energy dissipation maximization (Castillo, 2012). In addition, the cost of the conservation measures was estimated by using current market prices of local resources (for interventions with farmers own means) and national construction prices list (if the works were hired to an external company). The cost of the interventions was expressed as a multivariate function of the gully characteristic by means of regression analysis to facilitate its use for budget estimation purposes. Finally, these equations were applied to the farms included in the IPGC database to provide an estimation of the adequate budget required for a successful implementation of this initiative, as well as to propose unitary indexes (i.e. cost per gully meter in the longitudinal profile or per square meter in plan view) that could serve as useful criteria for this, or future programs, to allocate resources to individual farms based on specific characteristics of the gully erosion problems they suffer. References Castillo, C. 2012. Metodología de medida de la erosión por cárcavas y

  13. Thermokarst processes and the origin of crater-rim gullies in Utopia and western Elysium Planitia

    NASA Astrophysics Data System (ADS)

    Soare, R. J.; Kargel, J. S.; Osinski, G. R.; Costard, F.

    2007-11-01

    We have identified a number of gullies that could be aqueous in origin near or at the rim of several impact craters in Utopia Planitia and western Elysium Planitia (30.0°-59.0° N; 241.0°-291.0° W). Based on the sharpness of their incisions and the general absence of superposed craters, we ascribe a relatively recent origin to the gullies. Scalloped depressions are commonplace throughout the region, as well as on the crater walls, rims and floors near the areas of gully issuance. Occasionally, the depressions cross-cut the gully debris-aprons, suggesting that the formation of some depressions is even more recent than that of the gullies. Previous research has proposed that the depressions are collapse basins formed by thermokarst processes. On Earth, thermokarst landforms occur in areas of low gradient topography where the permanently frozen ground (permafrost) is ice rich and has undergone a change in thermal equilibrium. This change can be triggered by long-term or episodic/cyclic climate change and accompanying rises in mean temperatures towards ˜0 °C as well as by rises in seasonally sustained summer temperatures well above ˜0 °C. In order to explain the origin of the rim or near-rim gullies we invoke high obliquity and the possibility that this region of Mars experienced obliquity-driven rises in temperature, atmospheric pressure and humidity sufficient to keep surface water and near-surface ground-ice stable for extended periods of time. We propose that gully formation is closely related to local freeze-thaw processes that, in turn, generate a thermokarst landscape (of which the gullies are a part). This geological and climatological scenario comprises the following steps: An inundation of meltwater at high obliquity (due to the thawing of an atmospherically-deposited snowpack or ice-sheet) and the subsequent saturation of the underlying regolith to tens of metres of depth. Loss of water on the surface, perhaps as obliquity decreases slightly, followed

  14. Gully head retreat rates in the semi-arid highlands of Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Poesen, Jean; Deckers, Jozef; Haile, Mitiku; Nyssen, Jan

    2012-11-01

    Due to overgrazing and agricultural intensification, gully erosion severely affects sub-Saharan countries; however, insufficient quantitative studies exist for this part of the world. This paper presents data on gully head retreat rates in Northern Ethiopia and relates these rates to gully and environmental characteristics. The monitoring of headcuts over one rainy season (2010) revealed that present-day retreat rates are low, with average annual linear (Rl), areal (Ra) and volumetric (Ve) retreat rates of 0.34 m y- 1, 1.70 m2 y- 1 and 5.2 m3 y- 1, respectively. These results express the positive effects of recent soil and water conservation practices on gully stabilization. Significantly higher values of Rl (up to 1.93 m y- 1) occurred in the Vertisol areas affected by soil piping. When considering the medium- to long time scale (1-47 years) using archival terrestrial (and aerial) photographs, headcut retreat rates proved to be significantly higher than those in the short term. The averages for Rl, Ra and Ve are 3.8 m y- 1, 31.5 m2 y- 1 and 47.7 m3 y- 1, respectively. Retreat rates are up to 10 times higher after road construction. For the medium to long term, headcut retreat rates were positively related to the catchment area (A). A power relationship that best describes the relation between Ve and A is Ve = 0.53 A0.31 (r2 = 0.27, n = 18). Compared to other areas worldwide, regressive erosion has been rapid in Ethiopia as a result of the degraded and steep landscape combined with erosive rains and the occurrence of Vertisols. In Vertisols, headcut retreat is controlled by soil piping. Because no adequate techniques exist to control gully initiation and development in Vertisols, alternative techniques should be developed that deactivate soil pipes.

  15. Effects of coal-bed methane discharge waters on the vegetation and soil ecosystem in Powder River Basin, Wyoming

    USGS Publications Warehouse

    Stearns, M.; Tindall, J.A.; Cronin, G.; Friedel, M.J.; Bergquist, E.

    2005-01-01

    Coal-bed methane (CBM) co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from affected and reference sites (upland elevations and wetted gully) in Juniper Draw to investigate the effects of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation density and diversity. Results indicate an increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil are correlated with consistent exposure to CBM waters. Clay-loam soils in the study area have a much larger specific surface area than the sandy soils and facilitate a greater sodium adsorption. However, there was no significant relation between increasing water sodium adsorption ratio (SAR) values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species density was highest at the reference (upland and gully) and CBM affected upland sites. The affected gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the affected gully, implying a potential threat of invasion and competition to established native vegetation. These findings suggest that CBM waters could affect agricultural production operations and long-term water quality. ?? Springer 2005.

  16. Adsorption and desorption of noble gases on activated charcoal: II. sup 222 Rn studies in a monolayer and packed bed

    SciTech Connect

    Scarpitta, S.C.; Harley, N.H. )

    1990-10-01

    The adsorptive and desorptive characteristics of canisters containing a petroleum-based charcoal were investigated under controlled conditions of temperature, relative humidity, and Rn concentration. Charcoals exposed in a monolayer and packed bed during exposure intervals of 1-7 d demonstrate that Rn adsorption and desorption are dependent on bed depth and the amount of water adsorbed. Changes in the adsorptive and desorptive properties of the charcoal occurred near the break-point where the pores became occluded by water vapor that condenses in the entrance capillaries. Radon-222 adsorption is decreased by an order of magnitude as the amount of adsorbed water exceeds the break-point of the charcoal. The reduction in pore surface due to adsorbed water results in a marked increase in the rate of Rn loss from exposed canisters, accounting for reduced adsorption. The apparent desorption time-constant for a 2-cm bed of loose Witco 6 x 10 mesh charcoal containing 0.220-0.365 kg H{sub 2}O kg-1 is typically between 2-8 h. The apparent desorption time-constant for an equivalent packed bed containing a water vapor content of 0.026-0.060 kg H{sub 2}O kg-1, which is below the break-point of the charcoal, is about 15-30 h. Conventional charcoal canisters, if exposed in the fully-opened configuration, can achieve the break-point in less than 4 d at 70% humidity. The use of a diffusion barrier would allow for longer exposure times until the break-point of the charcoal is achieved.

  17. Adsorption and desorption of noble gases on activated charcoal: II. 222Rn studies in a monolayer and packed bed.

    PubMed

    Scarpitta, S C; Harley, N H

    1990-10-01

    The adsorptive and desorptive characteristics of canisters containing a petroleum-based charcoal were investigated under controlled conditions of temperature, relative humidity, and Rn concentration. Charcoals exposed in a monolayer and packed bed during exposure intervals of 1-7 d demonstrate that Rn adsorption and desorption are dependent on bed depth and the amount of water adsorbed. Changes in the adsorptive and desorptive properties of the charcoal occurred near the break-point where the pores became occluded by water vapor that condenses in the entrance capillaries. Radon-222 adsorption is decreased by an order of magnitude as the amount of adsorbed water exceeds the break-point of the charcoal. The reduction in pore surface due to adsorbed water results in a marked increase in the rate of Rn loss from exposed canisters, accounting for reduced adsorption. The apparent desorption time-constant for a 2-cm bed of loose Witco 6 x 10 mesh charcoal containing 0.220-0.365 kg H2O kg-1 is typically between 2-8 h. The apparent desorption time-constant for an equivalent packed bed containing a water vapor content of 0.026-0.060 kg H2O kg-1, which is below the break-point of the charcoal, is about 15-30 h. Conventional charcoal canisters, if exposed in the fully-opened configuration, can achieve the break-point in less than 4 d at 70% humidity. The use of a diffusion barrier would allow for longer exposure times until the break-point of the charcoal is achieved. PMID:2398008

  18. A Quantitative Study of Gully Erosion Based on Object-Oriented Analysis Techniques: A Case Study in Beiyanzikou Catchment of Qixia, Shandong, China

    PubMed Central

    Wang, Tao; He, Fuhong; Zhang, Anding; Gu, Lijuan; Wen, Yangmao; Jiang, Weiguo; Shao, Hongbo

    2014-01-01

    This paper took a subregion in a small watershed gully system at Beiyanzikou catchment of Qixia, China, as a study and, using object-orientated image analysis (OBIA), extracted shoulder line of gullies from high spatial resolution digital orthophoto map (DOM) aerial photographs. Next, it proposed an accuracy assessment method based on the adjacent distance between the boundary classified by remote sensing and points measured by RTK-GPS along the shoulder line of gullies. Finally, the original surface was fitted using linear regression in accordance with the elevation of two extracted edges of experimental gullies, named Gully 1 and Gully 2, and the erosion volume was calculated. The results indicate that OBIA can effectively extract information of gullies; average range difference between points field measured along the edge of gullies and classified boundary is 0.3166 m, with variance of 0.2116 m. The erosion area and volume of two gullies are 2141.6250 m2, 5074.1790 m3 and 1316.1250 m2, 1591.5784 m3, respectively. The results of the study provide a new method for the quantitative study of small gully erosion. PMID:24616626

  19. Curvilinear, interconnecting gullies and associated flow features as evidence for transient water flow on Vesta

    NASA Astrophysics Data System (ADS)

    Scully, J.; Russell, C. T.; Yin, A.; Jaumann, R.; McSween, H. Y.; Raymond, C. A.; Reddy, V.; Le Corre, L.

    2013-12-01

    The traditional view that airless small solar system bodies are completely dry is changing (e.g. Hsieh & Jewitt 2006). Vesta too has evidence for water: meteorites contain evidence for aqueous alteration (Treiman et al. 2004 & Warren et al. 2013) and water in primitive melts (Sarafian et al. 2012). Additionally, pitted terrain, formed by degassing of volatile-bearing material, is found in some craters (Denevi et al. 2012). Here we show that surface morphology in some craters, which contain pitted terrain, indicates that liquid water transiently flowed down the crater walls and formed curvilinear, interconnecting gullies, along with associated flow features inside and outside of the craters. Curvilinear gullies often end in lobate deposits, which are sometimes covered by pitted terrain. This association is evidence that volatiles are involved in the formation of curvilinear gullies. Well-defined examples of these morphologies are found in Cornelia and Marcia craters. Curvilinear gullies are qualitatively and quantifiably distinct from linear gullies, which are formed by dry granular flow of material. There is no physical mechanism identified that can explain dry granular flow forming both types of gullies. Moreover, curvilinear gullies are inconsistent with an impact melt origin. We further show that water can flow transiently on the surface of Vesta, which has no atmosphere and a low average surface temperature of ~145 K (Stubbs & Wang 2012). Sub-surface ice-bearing deposits can be retained and stable for billions of years on Vesta (Stubbs & Wang 2012). However, any sub-surface ice-bearing deposits are likely present in localized areas since curvilinear gullies and associated flow features are found in a minority of craters on Vesta, which are clustered into two groups. Since curvilinear gullies and associated flow features are always found in association with impact craters, it is proposed that an impact excavates to the ice-bearing deposit level and also

  20. Treatment of naphthalene-2-sulfonic acid from tannery wastewater by a granular activated carbon fixed bed inoculated with bacterial isolates Arthrobacter globiformis and Comamonas testosteroni.

    PubMed

    Song, Zhi; Edwards, Suzanne R; Burns, Richard G

    2006-02-01

    The kinetics of naphthalene-2-sulfonic acid (2-NSA) adsorption by granular activated carbon (GAC) were measured and the relationships between adsorption, desorption, bioavailability and biodegradation assessed. The conventional Langmuir model fitted the experimental sorption isotherm data and introduced 2-NSA degrading bacteria, established on the surface of the GAC, did not interfere with adsorption. The potential value of GAC as a microbial support in the aerobic degradation of 2-NSA by Arthrobacter globiformis and Comamonas testosteroni was investigated. Using both virgin and microbially colonised GAC, adsorption removed 2-NSA from the liquid phase up to its saturation capacity of 140 mg/g GAC within 48 h. However, between 83.2% and 93.3% of the adsorbed 2-NSA was bioavailable to both bacterial species as a source of carbon for growth. In comparison to the non-inoculated GAC, the combination of rapid adsorption and biodegradation increased the amount (by 70-93%) of 2-NSA removal from the influent phase as well as the bed-life of the GAC (from 40 to >120 d). A microbially conditioned GAC fixed-bed reactor containing 15 g GAC removed 100% 2-NSA (100 mg/l) from tannery wastewater at an empty bed contact time of 22 min for a minimum of 120 d without the need for GAC reconditioning or replacement. This suggests that small volume GAC bioreactors could be used for tannery wastewater recycling.

  1. Without gaps - 3D photo-reconstruction of gully headcuts by combined utilisation of UAV and close-range photogrammetry

    NASA Astrophysics Data System (ADS)

    Stöcker, Claudia; Karrasch, Pierre; Eltner, Anette

    2015-04-01

    Gully erosion is a worldwide phenomenon causing permanent degradation of fertile land. Especially in the Mediterranean, gullies contribute to high soil loss rates which necessitate multi-temporal and high resolution monitoring. Gullies naturally exhibit complex surface morphologies and hence are difficult to measure. Images acquired airborne or terrestrial are possible data sources for digital gully modelling due to availing of photogrammetric methods to achieve 3D models. In this regard unmanned airborne vehicles (UAVs) allow for low cost, flexible and frequent areal gully monitoring, but exhibit limitations as a result of the birds-eye view - i.e. at steep sidewalls and overhanging areas. Terrestrial images offer advantages at local assessments and can be obtained spontaneously as needed. However, images acquired from ground are not able to ensure areal coverage. To integrate the advantages of both data sources and to overcome the above mentioned limitations, this study introduces a methodological approach of combined utilisation of nadir UAV data and oblique terrestrial images for 3D photo reconstruction. Two gully headcuts in Andalusia (Spain) are analysed to confirm the suitability of the synergetic data usage. The results show that the UAV model of the gully, generated from images from flying heights of 15 m, implies inconsistency of data at slope gradients of 50 to 60 °. To eliminate these gaps additional terrestrial images can be integrated, which are geo-referenced solely using information of the already calculated 3D model and orthophoto from the UAV images. Referencing errors of the terrestrial point clouds are fixed by applying fine registration. The final merged digital gully model reveals a resolution of 0.5 cm and an accuracy of 1 cm. Concluding, high density point clouds based on the fusion of UAV and terrestrial image data show a significant improvement of 3D photo-reconstruction of two gully headcuts compared to detached processing of single data

  2. [Ecological adaptability of leaf epidermis of erosion-resistant plants in hilly-gully area of Loess Plateau, Northwest China].

    PubMed

    Miao, Fang; Du, Hua-Dong; Qin, Cui-Ping; Jiao, Ju-Ying

    2012-10-01

    By the temporary slide method of leaf epidermis, an observation was made on the morphological characteristics of the leaf epidermis of six erosion-resistant plant species in different soil erosion environments (gully, inter-gully, and inter-gully artificial Robinia pseudoacacia forest land) in hilly-gully area of Loess Plateau. Compared with those in the gully, the stomata aperture, stomata density, stomata index, stomata apparatus length/width plasticity, stomata apparatus area plasticity, epidermal hair density, and epidermal cell density of the leaf upper and lower epidermis of the plants in the inter-gully were 93.8% and 90.4%, 66.8% and 76.6%, 17.9% and 9.8%, 36.4% and 47.1%, 42.3% and 43.9%, 199.4% and 98.2%, and 46.5% and 50.1% higher, respectively; while in the inter-gully artificial R. pseudoacacia forest land, the same morphological indices of the leaf upper and lower epidermis of the plants were 66.7% and 106.7%, 20.5% and 45.8%, 11.9% and 11.9%, 37.9% and 41.3%, 19.8% and 21.2%, 113.1% and 52.2%, and 10.8% and 28.1% higher than those in the gully, respectively. The epidermal hair length and epidermal cell area of the leaf upper and lower epidermis of the plants in the inter-gully were 58.8% and 29.7%, and 40.3% and 37.0% lower than those in the gully, and the same morphological indices of the leaf upper and lower epidermis of the plants in the intergully artificial R. pseudoacacia forest land were respectively 25.0% and 23.6%, and 22.2% and 19.2% lower than those in the gully, respectively. The results suggested that the erosion-resistant plants in the study area were able to adapt to various soil erosion environments by increasing their leaf stomata aperture, stomata density, stomata index, stomata apparatus length/width plasticity, stomata apparatus area plasticity, epidermal hair density, and epidermal cell density, and by reducing their epidermal hair length and epidermal cell area.

  3. Characterizing the morphology of gully cross-sections based on PCA: A case of Yuanmou Dry-Hot Valley

    NASA Astrophysics Data System (ADS)

    Deng, Qingchun; Qin, Fachao; Zhang, Bin; Wang, Haipeng; Luo, Mingliang; Shu, Chengqiang; Liu, Hui; Liu, Gangcai

    2015-01-01

    A cross-section of a gully (GC) is important not only for computing the volume and rate of erosion of the gully but also for understanding the relationship of the gullying process, landforms, land use and erosional features. To effectively characterize the accurate morphology of GCs and to explain their statistical regularity, this study proposes 26 morphological parameters for describing the cross-sections of permanent gullies. We surveyed 456 GCs with a laser distance meter located at the mouth, middle and head of 152 gullies in the Yuanmou Dry-Hot Valley of China, mapped them with CASS software, and calculated the morphologic parameters. Based on principal component analysis (PCA), the morphological characteristics can be notably expressed by four principal components and fewer parameters with heavier load information. The first principal component (PC) reflected the dimensions of GCs, with the key parameters of width, depth, and area of the cross-section. Over 94% of the depth of the left side (dl), the top width (wt) and the area (s) were in the range of 0-12 m, 3-27 m, and 0-200 m2, respectively. The second PC indicated the degree of the gully's asymmetry in terms of the parameter of asymmetry ratio of width. There are 201 GCs of right-deflection and 184 of left-deflection. The third PC expressed the degree of erosion in terms of erosiveness and shape. There are 77 V-shaped, 25 U-shaped, and 354 intermediate shaped gullies. The percentage of U-shaped cross-sections is noticeably higher at the gully head than at the gully mouth and middle. The fourth PC reflects the erosional pattern difference. The value of the width/depth ratio was distributed and varied greatly within the range of 0.92-10.69 with an average value of 3.33. These key parameters differed at different locations and sites. The shape of GCs differs at different stages of development. Weathering crusts, soil properties, and vegetation cover are important for controlling the morphology of GCs in

  4. Mean circulation and high-frequency flow amplification in the Sable Gully

    NASA Astrophysics Data System (ADS)

    Greenan, Blair J. W.; Petrie, Brian D.; Cardoso, Diana A.

    2014-06-01

    The Sable Gully, a broad, shelf break submarine canyon approximately 40 km east of Sable Island on the eastern Scotian Shelf, separates Banquereau and Sable Island Banks. Unique among canyons on the eastern Canadian continental shelf because of its depth, steep slopes and extension far onto the shelf, its ecological significance and increasing human pressures led to its designation in 2004 under Canada's Oceans Act as the first Marine Protected Area (MPA) in the Atlantic Region. To improve the state of knowledge of the Gully MPA, a multi-disciplinary field program was carried out in 2006-07; the physical oceanographic component consisted of the deployment (April 2006) and recovery (August 2007) of four current meter moorings and CTD surveys. Analysis of this 16-month mooring deployment demonstrates that the mean circulation above the canyon rim (~200 m) is characterized by a southwestward flow that appears unaffected by the canyon topography. There is also some indication of the existence of an eddy at rim depth. Below 500 m, the circulation is dominated by an upcanyon flow (of order 0.02 m s-1) at the mooring array (halfway between the canyon head and mouth). The mean, 200 m-bottom transport towards the head of the Gully was estimated as 35,500 m3 s-1, implying an upwelling velocity of 1.7×10-4 m s-1 (14 m d-1) over the area. Results also show bottom-intensified tidal flows and non-linear constituents due to the interaction of K1, O1, M2 and S2 components along the thalweg of the canyon; the strong overtides and compound tides observed in the Gully make it unique among canyons. Further analyses provide evidence of enhanced mixing in the Gully (Kv~180×10-4 m2 s-1), which is approximately 20 times that observed on the adjoining Scotian Shelf. Total variance of the currents in the Gully is about 2.5 times greater than that observed on the nearby continental slope with an equivalent water depth.

  5. Linking long-term gully and river channel dynamics to environmental change using repeat photography (Northern Ethiopia)

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Nyssen, Jan; De Dapper, Morgan; Haile, Mitiku; Billi, Paolo; Munro, R. Neil; Deckers, Jozef; Poesen, Jean

    2011-06-01

    In the Highlands of Northern Ethiopia gully occurrence is linked to poverty-driven unsustainable use of the land in a vulnerable semi-arid and mountainous environment, where intensive rainfall challenges the physical integrity of the landscape. Trends in gully and river channel erosion, and their relation to triggering environmental changes can proffer valuable insights into sustainable development in Northern Ethiopia. In order to assess the region-wide change in gully and river channel morphology over 140 years, a set of 57 historical photographs taken in Tigray, and, clearly displaying gully cross-sections, were precisely repeated from 2006 till 2009. Ninety-two percent of the gully and river sections (n = 38) increased in cross-sectional area during the studied period, especially after 1975. Two repeatedly photographed catchments of Lake Ashenge and Atsela allowed a detailed study of gully development from 1936 until 2009. A conceptual hydrogeomorphic model was devised for these catchments and validated for the Northern Ethiopian Highlands. Three major phases can be distinguished in the hydrological regime of the catchments. In the first phase, between 1868 (or earlier) and ca. 1965, the relatively stable channels showed an oversized morphology inherited from a previous period when external forcing in environmental conditions had caused the channels to shape. In the second phase (ca. 1965 - ca. 2000), increased aridity and continued vegetation clearance accelerated the channel dynamics of the gully and river system. The third phase (ca. 2000 - present) started after the large-scale implementation of soil and water conservation measures. In 2009, 23% of the gully and river sections were stabilizing. This paper validates previous research indicating severe land degradation in the second half of the 20th century. Additionally, it demonstrates that the recent erosive cycle started around 1965 and, that at the present time, improved land management stabilizes

  6. Packed Bed Reactor Experiment

    NASA Video Gallery

    The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

  7. RADIOACTIVE DEMONSTRATIONS OF FLUIDIZED BED STEAM REFORMING AS A SUPPLEMENTARY TREATMENT FOR HANFORD'S LOW ACTIVITY WASTE AND SECONDARY WASTES

    SciTech Connect

    Jantzen, C.; Crawford, C.; Cozzi, A.; Bannochie, C.; Burket, P.; Daniel, G.

    2011-02-24

    The U.S. Department of Energy's Office of River Protection (ORP) is responsible for the retrieval, treatment, immobilization, and disposal of Hanford's tank waste. Currently there are approximately 56 million gallons of highly radioactive mixed wastes awaiting treatment. A key aspect of the River Protection Project (RPP) cleanup mission is to construct and operate the Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the RPP mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA), i.e. December 31, 2047. Therefore, Supplemental Treatment is required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. The Supplemental Treatment chosen will immobilize that portion of the retrieved LAW that is not sent to the WTP's LAW Vitrification facility into a solidified waste form. The solidified waste will then be disposed on the Hanford site in the Integrated Disposal Facility (IDF). In addition, the WTP LAW vitrification facility off-gas condensate known as WTP Secondary Waste (WTP-SW) will be generated and enriched in volatile components such as Cs-137, I-129, Tc-99, Cl, F, and SO4 that volatilize at the vitrification temperature of 1150 C in the absence of a continuous cold cap. The current waste disposal path for the WTP-SW is to recycle it to the supplemental LAW treatment to avoid a large steady state accumulation in the pretreatment-vitrification loop. Fluidized Bed Steam Reforming (FBSR) offers a moderate temperature (700-750 C) continuous method by which LAW and/or WTP-SW wastes can be processed irrespective of whether they contain organics, nitrates, sulfates/sulfides, chlorides

  8. [Discovery of Gullies on Mars Apparently Formed by Recent Seepage of Fluids

    NASA Technical Reports Server (NTRS)

    Knauth, L. Paul

    2004-01-01

    Most of the proposed objectives in this grant were achieved during the 3 year duration of the grant and its one year extension. In addition, shortly after initiation of the grant, the discovery of gullies on Mars apparently formed by recent seepage of fluids was announced. Together with partial support from the Astrobiology Institute, I devoted considerable effort during the grant interval into understanding the origin of these gullies because of their astrobiological significance. In addition, longstanding investigations of the environmental conditions of the Early Earth initiated years ago under previous NASA and NSF funding reached fruition and these were presented and published. This report summarizes the significant findings reported during the grant interval. Some of the work initiated during this interval has been completed under the subsequent Exobiology grant and will be reported at the appropriate time.

  9. Fluidized-bed combustion

    SciTech Connect

    Botros, P E

    1990-04-01

    This report describes the activities of the Morgantown Energy Technology Center's research and development program in fluidized-bed combustion from October 1, 1987, to September 30, 1989. The Department of Energy program involves atmospheric and pressurized systems. Demonstrations of industrial-scale atmospheric systems are being completed, and smaller boilers are being explored. These systems include vortex, multi-solid, spouted, dual-sided, air-cooled, pulsed, and waste-fired fluidized-beds. Combustion of low-rank coal, components, and erosion are being studied. In pressurized combustion, first-generation, combined-cycle power plants are being tested, and second-generation, advanced-cycle systems are being designed and cost evaluated. Research in coal devolatilization, metal wastage, tube corrosion, and fluidization also supports this area. 52 refs., 24 figs., 3 tabs.

  10. Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

    NASA Astrophysics Data System (ADS)

    Perreault, Naïm; Lévesque, Esther; Fortier, Daniel; Lamarque, Laurent J.

    2016-03-01

    Continuous permafrost zones with well-developed polygonal ice-wedge networks are particularly vulnerable to climate change. Thermo-mechanical erosion can initiate the development of gullies that lead to substantial drainage of adjacent wet habitats. How vegetation responds to this particular disturbance is currently unknown but has the potential to significantly disrupt function and structure of Arctic ecosystems. Focusing on three major gullies of Bylot Island, Nunavut, we estimated the impacts of thermo-erosion processes on plant community changes. We explored over 2 years the influence of environmental factors on plant species richness, abundance and biomass in 62 low-centered wet polygons, 87 low-centered disturbed polygons and 48 mesic environment sites. Gullying decreased soil moisture by 40 % and thaw-front depth by 10 cm in the center of breached polygons within less than 5 years after the inception of ice wedge degradation, entailing a gradual yet marked vegetation shift from wet to mesic plant communities within 5 to 10 years. This transition was accompanied by a five times decrease in graminoid above-ground biomass. Soil moisture and thaw-front depth changed almost immediately following gullying initiation as they were of similar magnitude between older (> 5 years) and recently (< 5 years) disturbed polygons. In contrast, there was a lag-time in vegetation response to the altered physical environment with plant species richness and biomass differing between the two types of disturbed polygons. To date (10 years after disturbance), the stable state of the mesic environment cover has not been fully reached yet. Our results illustrate that wetlands are highly vulnerable to thermo-erosion processes, which drive landscape transformation on a relative short period of time for High Arctic perennial plant communities (5 to 10 years). Such succession towards mesic plant communities can have substantial consequences on the food availability for herbivores and

  11. Erosional modification and gully formation at Meteor Crater, Arizona: Insights into crater degradation processes on Mars

    NASA Astrophysics Data System (ADS)

    Kumar, P. Senthil; Head, James W.; Kring, David A.

    2010-08-01

    Hydrogeological modification of Meteor Crater produced a spectacular set of gullies throughout the interior wall in response to rainwater precipitation, snow melting, and possible groundwater discharge. The crater wall has an exceptionally well-developed centripetal drainage pattern consisting of individual alcoves, channels, and fans. Some of the gullies originate from the rim crest and others from the middle crater wall where a lithologic transition occurs; broad gullies occur along the crater corner radial faults. Deeply incised alcoves are well developed on the soft Coconino Sandstone exposed on the middle crater wall, beneath overlying dolomite. In general, the gully locations are along crater wall radial fractures and faults, which are favorable locales of erosion due to preferential rock breakup from faulting, and groundwater flow/discharge; these structural discontinuities are also the locales where the surface runoff from rain precipitation and snow melting can preferentially flow, causing erosion and crater degradation. Channels are well developed on the talus deposits and alluvial fans on the periphery of the crater floor. Caves exposed on the lower crater level point to percolation of surface runoff and selective discharge through fractures on the crater wall. In addition, lake sediments on the crater floor provide significant evidence of a past pluvial climate, when the water table was higher, and groundwater may have seeped from springs on the crater wall. Although these hydrological processes continue at Meteor Crater today, conditions at the crater are much more arid than they were soon after impact, reflecting a climatic shift. This climate shift and the hydrological modifications observed at Meteor Crater provide insights for landscape sculpturing on Mars during various parts of its history.

  12. Gully erosion and land degradation in the Souss Basin, southern Morocco - application of airborne and terrestrial imagery and SfM procedures

    NASA Astrophysics Data System (ADS)

    Kaiser, Andreas; Peter, Klaus Daniel; Brings, Christine; Iserloh, Thomas; Seeger, Manuel; Ghafrani, Hassan; d'Oleire-Oltmanns, Sebastian; Marzolff, Irene; Ait Hssaine, Ali; Ries, Johannes B.

    2014-05-01

    Gully erosion is one major issue in soil erosion and land degradation. This major soil degradation process has affected the Souss Basin, located between the High and the Anti-Atlas, historically, and is increasing nowadays again. Since the 16th century, related to the production of sugar cane, gullies have been incising into the sedimentary fans and alluvial terraces. Today, the intensification of agro-industrial production of citrus fruit and vegetables has led to severe changes in surface geomorphology, and thus again to an increase of gully formation. For the understanding of the dynamics and formation of gullies, a combination of methods is needed, such as characterization of the precipitation patterns and quantification of infiltration and runoff generation dynamics as well as soil erosion rates within the gully catchments. In addition, the continuous and short-term monitoring of the gully morphology is essential in order to quantify the soil loss by gully erosion. Due to the complex 3-dimensional shapes of gullies, with overhangs and bank-cuttings, their assessment is a challenge. This paper aims at presenting a combination of terrestrial and airborne methods for quantifying the gully growth related to intensive agricultural productions in the Souss Basin (southern Morocco). Systematic series of images taken by a fixed-wing UAS are combined with detailed terrestrial images. Images were taken in different short-term to medium-term intervals of 11 months to 8 years, and 3D models were generated by means of structure from motion (SfM) algorithms. From these, gully growth volume and gully erosion rates could be quantified. In addition, the 3D visualization of the gully models - in contrast to more traditional 2.5D models common in GIS environments - allows new insights into the complex forms with undercuts, piping outlets etc and into the processes involved in their evolution.

  13. Bacillus cereus in free-stall bedding.

    PubMed

    Magnusson, M; Svensson, B; Kolstrup, C; Christiansson, A

    2007-12-01

    To increase the understanding of how different factors affect the bacterial growth in deep sawdust beds for dairy cattle, the microbiological status of Bacillus cereus and coliforms in deep sawdust-bedded free stalls was investigated over two 14-d periods on one farm. High counts of B. cereus and coliforms were found in the entire beds. On average, 4.1 log(10) B. cereus spores, 5.5 log(10) B. cereus, and 6.7 log(10) coliforms per gram of bedding could be found in the upper layers of the sawdust likely to be in contact with the cows' udders. The highest counts of B. cereus spores, B. cereus, and coliforms were found in the bedding before fresh bedding was added, and the lowest immediately afterwards. Different factors of importance for the growth of B. cereus in the bedding material were explored in laboratory tests. These were found to be the type of bedding, pH, and the type and availability of nutrients. Alternative bedding material such as peat and mixtures of peat and sawdust inhibited the bacterial growth of B. cereus. The extent of growth of B. cereus in the sawdust was increased in a dose-dependent manner by the availability of feces. Urine added to different bedding material raised the pH and also led to bacterial growth of B. cereus in the peat. In sawdust, a dry matter content greater than 70% was needed to lower the water activity to 0.95, which is needed to inhibit the growth of B. cereus. In an attempt to reduce the bacterial growth of B. cereus and coliforms in deep sawdust beds on the farm, the effect of giving bedding daily or a full replacement of the beds was studied. The spore count of B. cereus in the back part of the free stalls before fresh bedding was added was 0.9 log units lower in stalls given daily bedding than in stalls given bedding twice weekly. No effect on coliform counts was found. Replacement of the entire sawdust bedding had an effect for a short period, but by 1 to 2 mo after replacement, the counts of B. cereus spores in the

  14. Erosional development of bedrock spur and gully topography in the Valles Marineris, Mars

    NASA Technical Reports Server (NTRS)

    Patton, Peter C.

    1990-01-01

    Gully networks separated by resistant bedrock spurs are a common erosional feature along the escarpments that border the Valles Marineris. The resistant spur topography is best developed where the base of the slope is truncated by linear scarps interpreted as fault scarps. Regional variations in slope morphology imply that spur and gully topography undergoes a systematic progressive degradation through time associated with the erosional destruction of the basal fault scarps. The comparative morphometry of the divide networks indicates that the density of the spur networks and the number of first-order unbranched spurs decreases as the basal slope break becomes more sinuous. Abstraction of the spurs occurs through regolith storage in adjacent gullies at the slope base and the most degraded slope forms are entirely buried in talus. The basal fault scarps apparently control regolith transport by allowing debris to drain from the slope. As these basal scarps decay the slope base becomes increasingly sinuous and the slopes become transport limited. Dry mass-wasting may be the most important process acting on these slopes where a continually lowered base level is required to maintain the spur topography. In contrast to the Martian slopes, range front fault escarpments in the western U.S. show no systematic trend in spur network geometry as they are eroded. These weathering limited slopes are controlled by the more efficient removal of regolith through fluvial processes which rapidly create quasi-equilibrium drainage networks.

  15. The indication of Martian gully formation processes by slope-area analysis

    USGS Publications Warehouse

    Conway, S.J.; Balme, M.R.; Murray, J.B.; Towner, M.C.; Okubo, C.H.; Grindrod, P.M.

    2011-01-01

    The formation process of recent gullies on Mars is currently under debate. This study aims to discriminate between the proposed formation processes - pure water flow, debris flow and dry mass wasting - through the application of geomorphological indices commonly used in terrestrial geomorphology. High-resolution digital elevation models (DEMs) of Earth and Mars were used to evaluate the drainage characteristics of small slope sections. Data from Earth were used to validate the hillslope, debris-flow and alluvial process domains previously found for large fluvial catchments on Earth, and these domains were applied to gullied and ungullied slopes on Mars. In accordance with other studies, our results indicate that debris flow is one of the main processes forming the Martian gullies that were being examined. The source of the water is predominantly distributed surface melting, not an underground aquifer. Evidence is also presented indicating that other processes may have shaped Martian crater slopes, such as ice-assisted creep and solifluction, in agreement with the proposed recent Martian glacial and periglacial climate. Our results suggest that, within impact craters, different processes are acting on differently oriented slopes, but further work is needed to investigate the potential link between these observations and changes in Martian climate. ?? The Geological Society of London 2011.

  16. Loess relief degradation in urban peripheries and selected problems with land management (case study: Lipniak Gully, Lublin, E Poland)

    NASA Astrophysics Data System (ADS)

    Żuraw, Beata; Rodzik, Jan; Sosnowska, Małgorzata; Podsiedlik, Marek

    2016-04-01

    The research was conducted in the peripheral area of a relatively large city (350 thousand residents) in its major part located on a loess plateau. The study object was a neglected road gully dissecting a dry valley. Soil and sediment sampling permitted the reconstruction of the development of its relief from the Late Glacial, with particular consideration of anthropogenic changes. The history of land use was reconstructed based on archival maps and documentation. Plant associations were also identified. Land management was proposed in accordance with the principles of sustainable development. The studied landform was determined to originally constitute an erosional-denudational valley with asymmetric slopes, developed during the last phases of the Late Glacial. In the Holocene, the relief was strengthened by a oak-hornbean forest, where deep Luvisols developed. In the 19th century, the forest was gradually cleared, and the land was cultivated. A ground road was made along the valley floor. A road gully developed over a century of its use, with a depth of up to 4 m. Soil erosion on the slopes, uneven due to varied use, changed the direction of their asymmetry. In the 2nd half of the 20th century, low urban development reached the gully's vicinity, because the gully was designated the boundary of Lublin. Currently, the area is located within the city boundaries. The valley-gully system Lipniak, however, is wasteland along its considerable section. Plant succession occurred towards natural and ruderal associations. Neglecting the gully favours its inhabitancy by animals (among others foxes). Unfortunately, it also contributes to its littering. The local community has expressed the need for the management and ordering of the area to make it available for recreation with the maintenance of its natural values. In response to such needs, a project was prepared involving the construction of a walking-cycling path along the gully, connecting the nearby residential

  17. Effects of Coal-Bed Methane Discharge Waters on Soils and Vegetation Diversity

    NASA Astrophysics Data System (ADS)

    Stearns, M.; Tindall, J. A.; Friedel, M. J.; Cronin, G.; Berquist, E.

    2004-12-01

    Coal bed methane co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from impacted and reference sites (upland elevations and wetted gully) to investigate impacts of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation richness and diversity. Results indicate a significant increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil appear to be due to consistent exposure to CBM waters. Clay-loam soils in the study area, which have a much larger specific surface area than the sandy soils, readily allow sodium ions to adsorb quickly to exchange sites. There was no significant relation between increasing water SAR values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species richness was highest at the reference (upland and gully) and impacted upland sites. The impacted gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the impacted gully, implicating a potential threat of invasion and competition to established native vegetation. CBM waters could have detrimental impacts to the local ecosystem, causing dispersion of soils and making it difficult for native vegetation to exist. These waters could also have a devastating effect on agricultural production operations and long-term water quality.

  18. The interaction of human activities and geological processes: a geo-environmental study in Southeastern Nigeria (Owerri urban area)

    NASA Astrophysics Data System (ADS)

    Sowa, A. H. O.; Ibe, K. M.

    1992-05-01

    The aim of this study is to analyze the mechanisms of interaction between the factors human activity, water, vegetation and related geological processes, like gully erosion or filling up of river beds. A surface water and land pollution survey of Owerri urban area, Nigeria, has been carried out in order to establish the current levels of pollution. An attempt has been made to show the relationships between population density, industrial and agricultural activities, environmental contamination, and soil erodibility. The spatial distribution of pollutants due to poor land use system and human activities were investigated, thus emphasizing the need for integrated planning development as a preventive measure for reducing environmental impacts in fast-growing urban centres of developing countries.

  19. Effect of bedding materials on concentration of odorous compounds and in beef cattle bedded manure packs.

    PubMed

    Spiehs, Mindy J; Brown-Brandl, Tami M; Parker, David B; Miller, Daniel N; Berry, Elaine D; Wells, James E

    2013-01-01

    The objectives of this study were to determine the effect of bedding material (corn stover, soybean stover, wheat straw, switchgrass, wood chips, wood shavings, corn cobs, and shredded paper) on concentration of odorous volatile organic compounds (VOC) in bedded pack material and to determine the effect of bedding material on the levels of total in laboratory-scaled bedded manure packs. Four bedded packs of each bedding material were maintained for two 6-wk periods ( = 64). Straight- and branched-chained fatty acids and aromatic compounds were measured. Corn cob bedding had the highest concentration of odorous VOC, and wood shavings had the lowest ( < 0.01). Calculated odor activity values were highest for corn cob bedding and shredded paper and lowest for wood shavings ( < 0.01). concentrations decreased from week to week for all treatments from Week 2 to Week 6. At Week 6, levels in bedded packs with shredded paper were higher ( < 0.05) than bedded packs containing wood shavings, wood chips, or switchgrass ( < 0.05). At Weeks 4, 5, and 6, concentrations in bedded packs with wood shavings were lower ( < 0.05) than bedded packs of all treatments except wood chips. Results of this study indicate that ground corn cobs or shredded paper may increase odor production and shredded paper may increase when used in deep-bedded livestock facilities, whereas wood shavings may have the least impact on air quality and . PMID:23673740

  20. Using high-resolution fiber-optic distributed temperature sensing to measure spatially resolved speed and temperature of airflows in a shallow gully

    NASA Astrophysics Data System (ADS)

    Thomas, Christoph; Sayde, Chadi; Selker, John

    2015-04-01

    We present a novel observational technique that was applied to study transient shallow cold-air drainages and pools in undulating terrain in weak-wind conditions. Wind speed and air temperature at thousands of closely co-located locations were measured simultaneously at high spatial (0.25m) and temporal (5s) resolution using paired passive and actively heated optical fibers with a distributed temperature sensing system (DTS). The fibers were deployed in a transect across a shallow gully with a total length of 230 m at three levels (0.5, 1, and 2m above ground level) during the Shallow Cold Pool (SCP) Experiment in Northern Colorado, USA in October and November 2012. While we previously demonstrated that air temperature and the thermal structure of the near-surface turbulence can be observed with the DTS technique (Thomas et al., 2012, Zeeman et al., 2014), the novelty here consists of additionally measuring wind speed on horizontal scales of several hundreds of meters with fine resolution. Analogous to a hot-wire anemometer, the approach is based on the principal of velocity-dependent heat transfer from a heated surface. We present the theoretical basis for the DTS wind and temperature measurements and validate it against point observations from sonic anemometers and thermo-hygrometers. A space-time analysis of the near-surface gully flow and temperature field is presented based upon the observations subject to an orthogonal multi-resolution decomposition for selected cases. The temporal variability of near-surface air temperature was largest half-way up the slope caused be shifts of the very sharp thermal boundary between the density driven cold-air drainage flow in the gully bottom and the lower density air on the slopes, which was significantly warmed by enhanced downward mixing of sensible heat in the lee of the gully shoulder. Stationary horizontal temperature gradients at this thermal boundary amounted to 6 to 8 K m-1 and persisted for several hours unless

  1. Integration of fuzzy logic and image analysis for the detection of gullies in the Calhoun critical zone observatory using airborne LiDAR data

    NASA Astrophysics Data System (ADS)

    Bastola, S.; Noto, L. V.; Dialynas, Y. G.; Bras, R. L.

    2015-12-01

    The entire Piedmont of the Southeastern United States, where the Calhoun Critical Zone Observatory (CCZO) is located, experienced one of the most severe erosive events in the United States during last two centuries. Forested areas were cleared to cultivate cotton, tobacco and other crops during the nineteenth and early twentieth century and these land use change, together with intense rainfalls, initiated deep gullying. An accurate mapping of these landforms is important since, despite some gully stabilization and reforestation efforts, gullies are still major contributors of sediment to streams. Mapping gullies in the CCZO area is hindered by the presence of dense canopy which precludes the identification through aerial photogrammetry and other traditional remote sensing methods. Moreover, the wide spatial extent of the gullies makes detailed field surveys, for the identification and characterization of entire gullies, a very large and expensive proposition. This work aims to develop and assess an automated set of algorithms to detect and map gullies using morphological characteristics retrieved by very high resolution imagery (VHRI). A one-meter resolution LiDAR DEM is used to derive different morphometric indices whose combination, carried out using spatial analysis methods and fuzzy logic rules, are a tool to identify gullies. This spatial model has been calibrated using the reference perimeters of two gullies that we measured during a recent field survey. The entire procedure attempts to provide estimates of gully erosion patterns, which characterize the entire Calhoun CZO area and to develop and evaluate a method to measure characteristic features of gullies (i.e. depth and volume).

  2. Dynamic bed reactor

    SciTech Connect

    Stormo, K.E.

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix. 27 figs.

  3. Dynamic bed reactor

    DOEpatents

    Stormo, Keith E.

    1996-07-02

    A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

  4. Variations in vegetation cover and topography control gully density and sediment production on the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Jianlin; Govers, Gerard

    2016-04-01

    The factors controlling topsoil erosion rates are relatively well understood. This explains why topsoil erosion rates on the Chinese loess plateau (CLP) can be relatively accurately estimated using a combination of empirical data and relatively simple models (Zhao et al., in press). This is, however, not the case for non-topsoil erosion (sediment production by gullying and landslides): while it is well known that these processes produce significant amounts of sediment, the factors controlling their intensity on the CLP are far less understood. In this study, the contribution of non-topsoil erosion to total sediment production on the CLP was investigated. We estimated non-topsoil erosion rates (ENT) by making the difference between measured total sediment yield and the estimated topsoil erosion in 46 gauged catchments on the CLP for the period 1950-1970, when soil conservation measures were mostly absent in the area. We tested an extensive set of environmental variables related to topography, climate and the impact of land use for correlation Our results showed that the average catchment erosion rate (E) and ENT between 1950 and 1970 were 68.29 tha-1yr-1 and 58.02 tha-1yr-1 respectively. The sediment contribution of non-topsoil erosion to total sediment production ranged between 0 and 97% with a mean of 70%. Both E and ENT were significantly related with river slope, land use, NDVI, and gully density. However, gully density was the only variable explaining a major part of the variance in both E (60%) and ENT (57%). Gully density itself was significantly related to topography and vegetation cover but not to precipitation. Importantly, gully density was not only related to overall slope steepness, but also the river gradients and the hypsometric integral, suggesting that not only land cover disturbance but also tectonic uplift may control gully density and erosion rates. The absence of a clear climate signal, both with respect to the variation in gully density and in

  5. Variations in vegetation cover and topography control gully density and sediment production on the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Jianlin; Govers, Gerard

    2016-04-01

    The factors controlling topsoil erosion rates are relatively well understood. This explains why topsoil erosion rates on the Chinese loess plateau (CLP) can be relatively accurately estimated using a combination of empirical data and relatively simple models (Zhao et al., in press). This is, however, not the case for non-topsoil erosion (sediment production by gullying and landslides): while it is well known that these processes produce significant amounts of sediment, the factors controlling their intensity on the CLP are far less understood. In this study, the contribution of non-topsoil erosion to total sediment production on the CLP was investigated. We estimated non-topsoil erosion rates (ENT) by making the difference between measured total sediment yield and the estimated topsoil erosion in 46 gauged catchments on the CLP for the period 1950-1970, when soil conservation measures were mostly absent in the area. We tested an extensive set of environmental variables related to topography, climate and the impact of land use for correlation Our results showed that the average catchment erosion rate (E) and ENT between 1950 and 1970 were 68.29 tha‑1yr‑1 and 58.02 tha‑1yr‑1 respectively. The sediment contribution of non-topsoil erosion to total sediment production ranged between 0 and 97% with a mean of 70%. Both E and ENT were significantly related with river slope, land use, NDVI, and gully density. However, gully density was the only variable explaining a major part of the variance in both E (60%) and ENT (57%). Gully density itself was significantly related to topography and vegetation cover but not to precipitation. Importantly, gully density was not only related to overall slope steepness, but also the river gradients and the hypsometric integral, suggesting that not only land cover disturbance but also tectonic uplift may control gully density and erosion rates. The absence of a clear climate signal, both with respect to the variation in gully density

  6. Bed-exit alarm effectiveness

    PubMed Central

    Capezuti, Elizabeth; Brush, Barbara L.; Lane, Stephen; Rabinowitz, Hannah U.; Secic, Michelle

    2009-01-01

    This study describes the accuracy of two types of bed-exit alarms to detect bed-exiting body movements: pressure-sensitive and a pressure sensitive combined with infrared beam detectors (dual sensor system). We also evaluated the occurrence of nuisance alarms, or alarms that are activated when a participant does not attempt to get out of bed. Fourteen nursing home residents were directly observed for a total of 256 nights or 1,636.5 hours; an average of 18.3 ± 22.3 (± S.D.) nights/participant for an average of 6.4 ± 1.2 hours/night. After adjusting for body movements via repeated measures, Poisson regression modeling, the least squares adjusted means show a marginally significant difference between the type of alarm groups on the number of true positives (mean/S.E.M. = 0.086/1.617) for pressure-sensitive vs. dual sensor alarm (0.593/1.238; p = 0.0599) indicating that the dual sensor alarm may have a higher number of true positives. While the dual sensor bed-exit alarm was more accurate than the pressure sensitive alarm in identifying bed-exiting body movements and reducing the incidence of false alarms, false alarms were not eliminated altogether. Alarms are not a substitute for staff; adequate staff availability is still necessary when residents need or wish to exit bed. PMID:18508138

  7. Bed-exit alarm effectiveness.

    PubMed

    Capezuti, Elizabeth; Brush, Barbara L; Lane, Stephen; Rabinowitz, Hannah U; Secic, Michelle

    2009-01-01

    This study describes the accuracy of two types of bed-exit alarms to detect bed-exiting body movements: pressure-sensitive and a pressure-sensitive combined with infrared (IR) beam detectors (dual sensor system). We also evaluated the occurrence of nuisance alarms, or alarms that are activated when a participant does not attempt to get out of bed. Fourteen nursing home residents were directly observed for a total of 256 nights or 1636.5h; an average of 18.3+/-22.3 (+/-S.D.) nights/participant for an average of 6.4+/-1.2 h/night. After adjusting for body movements via repeated measures, Poisson regression modeling, the least squares adjusted means (LSM) show a marginally significant difference between the type of alarm groups on the number of true positives (NTP) (mean/S.E.M.=0.086/1.617) for pressure-sensitive versus dual sensor alarm (0.593/1.238; p=0.0599) indicating that the dual sensor alarm may have a higher NTP. While the dual sensor bed-exit alarm was more accurate than the pressure-sensitive alarm in identifying bed-exiting body movements and reducing the incidence of false alarms, false alarms were not eliminated altogether. Alarms are not a substitute for staff; adequate staff availability is still necessary when residents need or wish to exit bed.

  8. The role of settling velocity formulation in the determination of gully pot trapping efficiency: comparison between analytical and experimental data.

    PubMed

    Ciccarello, Annalisa; Bolognesi, Andrea; Maglionico, Marco; Artina, Sandro

    2012-01-01

    Roadside gully pots are the connecting points between surface runoff and the underground drainage network; therefore they can be considered as the most superficial component of urban drainage systems. Gully pots are supposed to trap particulate matter washed off the catchment surface, but also to collect and convey stormwater into the network. The continuous accumulation of particulate matter results in a progressive loss of the gully pot hydraulic conveyance, thereby increasing the probability of urban flooding during rainstorm events. This study has therefore the objective to determine which variables influence the gully pot capability of retaining solids (efficiency), both experimentally and analytically. Several laboratory tests have been performed on a simple plastic gully pot, with different inflow rates and using both mono and hetero-disperse particle samples. Particular attention has been given to the influence exerted by the way particle settling velocity is expressed: efficiency has been analytically determined by means of multiple settling velocity formulas proposed by various authors and eventually compared to experimental data. Results deriving from the adoption of each single settling velocity formula have been extensively analysed, showing fairly different outcomes.

  9. Hydrological connectivity via gully formation in tropical watersheds limits the effectiveness of riparian buffers in protecting streams

    NASA Astrophysics Data System (ADS)

    Ometto Bezerra, M.; Filoso, S.; Palmer, M.

    2015-12-01

    We tested the hypotheses that increased hydrological connectivity is associated with gully formation due to sugarcane agriculture, and, that this in turn, compromises the effectiveness of stream riparian buffers at protecting streams. Based largely on results from temperate regions, national-level programs to restore riparian buffers have been promoted in tropical countries like Brazil. The assumption is that the buffers would mitigate the impacts of agriculture on stream hydrology and water quality. We show however that the combination of intensive agriculture and heavy seasonal rainfall (which is characteristic of many tropical regions) causes gully formation thereby expanding the drainage network and increasing the hydrological connectivity between streams and their uplands. The result is that excess runoff and associated materials from croplands and from the gullies themselves can enter stream channels directly without interaction with a riparian buffer. Focusing on 11 first-order streams in Brazil, we quantified the relationship between a suite of landscape metrics, the hydrologic response to storm events (i.e., stream flashiness) and changes in suspended sediment concentrations. We included novel metrics describing the hydrological connectivity via gully. We demonstrate that streams more hydrologically connected to their uplands via gullies were flashier and had greater suspended sediment concentrations. Based on the quantitative relationships we found, we propose alternatives to current management practices.

  10. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that group of woven cloth products used as coverings on a bed. Bedding includes products such as...

  11. Identification and activities in situ of Nitrosospira and Nitrospira spp. as dominant populations in a nitrifying fluidized bed reactor

    SciTech Connect

    Schramm, A.; Beer, D. de; Amann, R.; Wagner, M.

    1998-09-01

    Bacterial aggregates from a chemolithoautotrophic, nitrifying fluidized bed reactor were investigated with microsensors and rRNA-based molecular techniques. The microprofiles of O{sub 2}, NH{sub 4}{sup +}, NO{sub 2}{sup {minus}}, and NO{sub 3}{sup {minus}} demonstrated the occurrence of complete nitrification in the outer 125 {micro}m of the aggregates. The ammonia oxidizers were identified as members of the Nitrosospira group by fluorescence in situ hybridization (FISH). No ammonia- or nitrate-oxidizing bacteria of the genus Nitrosomonas or Nitrobacter, respectively, could be detected by FISH. To identify the nitrite oxidizers, a 16S ribosomal DNA clone library was constructed and screened by denaturing gradient gel electrophoresis and selected clones were sequenced. The organisms represented by these sequences formed two phylogenetically distinct clusters affiliated with the nitrite oxidizer Nitrospira moscoviensis. 16S rRNA-targeted oligonucleotide probes were designed for in situ detection of these organisms. FISH analysis showed that the dominant populations of Nitrospira spp. and Nitrosospira spp. formed separate, dense clusters which were in contact with each other and occurred throughout the aggregate. A second, smaller, morphologically and genetically different population of Nitrospira spp. was restricted to the outer nitrifying zones.

  12. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

    A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

  13. Age-Orientation Relationships of Northern Hemisphere Martian Gullies and "Pasted-on" Mantling Unit: Implications for Near-Surface Water Migration in Mars' Recent History

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Lackner, C. N.

    2005-01-01

    The finding of abundant, apparently young, Martian gullies with morphologies indicative of formation by flowing fluid was surprising in that volumes of near-surface liquid water in sufficient quantities to modify the surface geology were not thought possible under current conditions. Original hypotheses on origin of gullies were mostly centered on groundwater seepage and surface runoff and melting of near-surface ground ice. More recently, melting of snow deposited in periods of higher obliquity has been proposed as a possible origin of the gullies. Tied to this hypothesis is the supposition that the "pasted-on" mantling unit observed in association with many gullies is composed of remnant snowpack. The mantling unit has distinct rounded edge on its upper boundary and exhibits features suggestive of flow noted that the uppermost part of the mantle marks where gullies begin, suggesting that the source of water for the gullies was within the mantle. The mantle is found preferentially on cold, pole-facing slopes and, where mantled and non-mantled slopes are found together, gullies are observed incised into the latter. In other cases, the mantling material lacks gullies.

  14. Modeling the Contribution of Ephemeral Gully Erosion Under Different Soil Management in An Olive Orchard Microcatchment Using AnnAGNPS Model

    EPA Science Inventory

    In Spain, few studies have been carried out to explore the erosion caused by processes other than interrill and rill erosion, such as gully and ephemeral gully erosion, especially because most of the available studies have evaluated the erosion at plot scale. A study about the en...

  15. A Preliminary Relationship Between the Depth of Martian Gullies and the Abundance of Hydrogen on Near-Surface Mars

    NASA Technical Reports Server (NTRS)

    Frey, E. L.; Sakimoto, S. E. H.; Frey, H. V.

    2004-01-01

    Recent compelling evidence has been presented to suggest the presence of near-surface water or water ice on Mars. The Mars Orbiter Camera (MOC) has photographed relatively young fluvial features in the form of gullies which have been attributed to groundwater seepage. The Gamma Ray Spectrometer (GRS) from the Mars Odyssey spacecraft has detected large amounts of hydrogen in the Martian soil, inferred to come from water or water ice within the upper meter of the surface. We explore the model of groundwater seepage as the mechanism of gully formation as opposed to other mechanisms. We investigate the abundance of hydrogen to the depth at which gully-like features form. We see a positive correlation, which implies the presence of a groundwater system for Mars.

  16. Removal of selected pharmaceuticals from domestic wastewater in an activated sludge system followed by a horizontal subsurface flow bed - analysis of their respective contributions.

    PubMed

    Verlicchi, P; Galletti, A; Petrovic, M; Barceló, D; Al Aukidy, M; Zambello, E

    2013-06-01

    Seventy-three commonly administered pharmaceuticals from twelve different therapeutic classes were investigated at a municipal wastewater treatment plant in northern Italy featuring a conventional activated sludge system (full-scale) and a polishing horizontal subsurface flow bed (pilot plant). Removal of these micro-pollutants by the two systems was assessed in order to evaluate their respective contributions. Mean concentrations and standard deviations were calculated and found to differ for the compounds detected, ranging from few ng/L to over 1,165 ng/L in the secondary effluent and from 11 to 533 in the polished effluent. Eighteen compounds were consistently below the detection limit and the remaining 55 compounds were found at a minimum of one sampling point. Average removal efficiencies of both treatment steps and in treatment train as a whole are evaluated and discussed, highlighting the difficulties in predicting the fate of pharmaceuticals in both an activated sludge system and a horizontal subsurface flow bed. Comparison between the observed average removal efficiencies and those reported in the literature was also carried out for the pharmaceuticals of interest, and the discrepancies that emerged are discussed. The investigated constructed wetland did show efficacy in removing some of these compounds, and it contributed to the overall removal efficiency of each therapeutic class. Indeed, evaluation of the specific mass loadings of each class of PhC detected in the raw wastewaters, secondary and polished effluent evidences that the investigated constructed wetland is able to further reduce the load of micropollutants, which could become a necessity, especially where the receiving water body is an effluent-dominant river and mitigation measures of the discharge impact are required to protect and safeguard the aquatic environment. PMID:23563255

  17. Characterization of Mason Gully (H5): The second recovered fall from the Desert Fireball Network

    NASA Astrophysics Data System (ADS)

    Dyl, Kathryn A.; Benedix, Gretchen K.; Bland, Phil A.; Friedrich, Jon M.; Spurný, Pavel; Towner, Martin C.; O'Keefe, Mary Claire; Howard, Kieren; Greenwood, Richard; Macke, Robert J.; Britt, Daniel T.; Halfpenny, Angela; Thostenson, James O.; Rudolph, Rebecca A.; Rivers, Mark L.; Bevan, Alex W. R.

    2016-03-01

    Mason Gully, the second meteorite recovered using the Desert Fireball Network (DFN), is characterized using petrography, mineralogy, oxygen isotopes, bulk chemistry, and physical properties. Geochemical data are consistent with its classification as an H5 ordinary chondrite. Several properties distinguish it from most other H chondrites. Its 10.7% porosity is predominantly macroscopic, present as intergranular void spaces rather than microscopic cracks. Modal mineralogy (determined via PS-XRD, element mapping via energy dispersive spectroscopy [EDS], and X-ray tomography [for sulfide, metal, and porosity volume fractions]) consistently gives an unusually low olivine/orthopyroxene ratio (0.67-0.76 for Mason Gully versus ~1.3 for typical H5 ordinary chondrites). Widespread "silicate darkening" is observed. In addition, it contains a bright green crystalline object at the surface of the recovered stone (diameter ≈ 1.5 mm), which has a tridymite core with minor α-quartz and a rim of both low- and high-Ca pyroxene. The mineralogy allows the calculation of the temperatures and ƒ(O2) characterizing thermal metamorphism on the parent body using both the two-pyroxene and the olivine-chromite geo-oxybarometers. These indicate that MG experienced a peak metamorphic temperature of ~900 °C and had a similar ƒ(O2) to Kernouvé (H6) that was buffered by the reaction between olivine, metal, and pyroxene. There is no evidence for shock, consistent with the observed porosity structure. Thus, while Mason Gully has some unique properties, its geochemistry indicates a similar thermal evolution to other H chondrites. The presence of tridymite, while rare, is seen in other OCs and likely exogenous; however, the green object itself may result from metamorphism.

  18. Recent (Late Amazonian) enhanced backweathering rates on Mars: Paracratering evidence from gully alcoves

    NASA Astrophysics Data System (ADS)

    Haas, Tjalling; Conway, Susan J.; Krautblatter, Michael

    2015-12-01

    Mars is believed to have been exposed to low planet-wide weathering and denudation since the Noachian. However, the widespread occurrence of alcoves at the rim of pristine impact craters suggests locally enhanced recent backweathering rates. Here we derive Late Amazonian backweathering rates from the alcoves of 10 young equatorial and midlatitude craters. The enhanced Late Amazonian Martian backweathering rates (10-4-10-1 mm yr-1) are approximately 1 order of magnitude higher than previously reported erosion rates and are similar to terrestrial rates inferred from Meteor crater and various Arctic and Alpine rock faces. Alcoves on initially highly fractured and oversteepened crater rims following impact show enhanced backweathering rates that decline over at least 101-102 Myr as the crater wall stabilizes. This "paracratering" backweathering decline with time is analogous to the paraglacial effect observed in rock slopes after deglaciation, but the relaxation timescale of 101-102 Myr compared to 10 kyr of the Milankovitch-controlled interglacial duration questions whether a paraglacial steady state is reached on Earth. The backweathering rates on the gullied pole-facing alcoves of the studied midlatitude craters are much higher (˜2-60 times) than those on slopes with other azimuths and those in equatorial craters. The enhanced backweathering rates on gullied crater slopes may result from liquid water acting as a catalyst for backweathering. The decrease in backweathering rates over time might explain the similar size of gullies in young (<1 Ma) and much older craters, as alcove growth and sediment supply decrease to low-background rates over time.

  19. Recent (Late Amazonian) enhanced backweathering rates on Mars: Paracratering evidence from gully alcoves

    NASA Astrophysics Data System (ADS)

    de Haas, Tjalling; Conway, Susan; Krautblatter, Michael

    2016-04-01

    Mars is believed to have been exposed to low planet-wide weathering and denudation since the Noachian period (˜4.1 - 3.7 Ga). However, the widespread occurrence of alcoves at the rim of pristine impact craters suggests locally enhanced recent backweathering rates. Here we derive Late Amazonian backweathering rates from the alcoves of 10 young equatorial and mid-latitude craters, ranging in age from 0.2 to 45 Ma. The enhanced Late Amazonian Martian backweathering rates (10-4 - 10-1 mm yr-1) are approximately one order of magnitude higher than previously reported erosion rates, and are similar to terrestrial rates inferred from Meteor crater and various Arctic and Alpine rock faces, when corrected for age. Alcoves on initially highly fractured and oversteepened crater rims following impact show enhanced backweathering rates that decline over at least 101 - 102 Myr as the crater wall stabilizes. This 'paracratering' backweathering decline with time is analogous to the paraglacial effect observed in rock slopes after deglaciation, but the relaxation time scale of 101 - 102 Myr compared to 10 kyr of the Milankovitch-controlled interglacial duration questions whether a paraglacial steady state is reached on Earth. The backweathering rates on the gullied pole-facing alcoves of the studied mid-latitude craters are much higher (˜2 - 60 times) than those on slopes with other azimuths and those in equatorial craters. The enhanced backweathering rates on gullied crater slopes may result from liquid water acting as a catalyst for backweathering. The decrease in backweathering rates over time might explain the similar size of gullies in young (<1 Ma) and much older craters, as alcove growth and sediment supply decrease to low background rates over time.

  20. Extensive rill erosion and gullying on abandoned pit mining sites in Lusatia, Germany

    NASA Astrophysics Data System (ADS)

    Kunth, Franziska; Kaiser, Andreas; Vláčilová, Markéta; Schindewolf, Marcus; Schmidt, Jürgen

    2015-04-01

    As the major economic driver in the province of Lusatia, Eastern Germany, the large open-cast lignite mining sites characterize the landscape and leave vast areas of irreversible changed post-mining landscapes behind. Cost-intensive renaturation projects have been implemented in order to restructure former mine sites into stabile self-sustaining ecosystems and local recreation areas. With considerable expenditure the pits are stabilized, flooded and surrounding areas are restructured. Nevertheless, heavy soil erosion, extensive gullying and slope instability are challenges for the restructuring and renaturation of the abandoned open-cast mining sites. The majority of the sites remain inaccessible to the public due to instable conditions resulting in uncontrolled slides and large gullies. In this study a combined approach of UAV-based aerial imagery, 3D multi-vision surface reconstruction and physically-based soil erosion modelling is carried out in order to document, quantify and better understand the causes of erosion processes on mining sites. Rainfall simulations have been carried out in lausatian post mining areas to reproduce soil detachment processes and observe the responsible mechanisms for the considerable erosion rates. Water repellency and soil sealing by biological crusts were hindering infiltration and consequently increasing runoff rates despite the mainly sandy soil texture. On non-vegetated experimental plots runoff coefficients up to 87 % were measured. In a modelling routine for a major gully catchment regarding a 50 years rainfall event, simulation results reveal runoff coefficients of up to 84% and erosion rates of 118 Mg*ha^-1. At the sediment pass over point 450Mg of sediments enter the surface water bodies. A system response of this order of magnitude were unexpected by the authorities. By applying 3D multi-vision surface reconstruction a model validation is now possible and further may illustrate the great importance of soil conservation

  1. Simulation for Artificial Forest Succession in Hilly-gully Area of Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Zhao, J., Jr.; Zhao, Z.; Yang, Y.

    2015-12-01

    The wide and large afforestation caused the great changes of surface albedo, water cycles, soil compositions and regional climate conditions on the Loess Plateau. There was increasing evidence showed that many problems had been occurred since ecological protection program began. Whether the artificial forest would adapt to environmental conditions on Loess Plateau is still controversial. In this paper, LANDIS-II, a spatially explicit model which included extension modules such as succession, disturbance, seed propagation, forest management, carbon dynamics and climate change, was applied to simulate dynamic natural succession of forests for coming 300 years in hilly-gully area of Loess Plateau. The results showed that (1) During the advancement of succession, the study area was occupied by different communities and appeared different succession stage successively under the condition of without considering the disturbance; (2) The current artificial forest has changed from 93.31% of Robinia pseudoacacia to exit the forest community in 50 years; (3) Platycladus oriental was the dominant species of coniferous trees and Populus davidiana was the dominant species of deciduous trees; (4)During the late succession stage, Platycladus oriental replaced Pinus tabulaeformis becoming the largest areal proportion of dominant tree species. The simulating of the natural succession in hilly-gully area of Loess Plateau forests at large space and long term scales, could provide a scientific basis for rational allocation of forest resources and forest management. In addition, our work clarifies the challenges and opportunities for the application of the model in the artificial forest and in hilly-gully area of Loess Plateau, China.

  2. Practice Hospital Bed Safety

    MedlinePlus

    ... Bed? Todd says that there is no standard definition for hospital beds, a fact that consumers shopping ... in retail stores that don’t meet the definition of medical devices under the law, but which ...

  3. Enuresis (Bed-Wetting)

    MedlinePlus

    ... their development. Bed-wetting is more common among boys than girls. What causes bed-wetting? A number of things ... valves in boys or in the ureter in girls or boys Abnormalities in the spinal cord A small bladder ...

  4. Can bioengineering structures made of willow cuttings trap sediment in eroded marly gullies in a Mediterranean mountainous climate?

    NASA Astrophysics Data System (ADS)

    Rey, Freddy; Burylo, Mélanie

    2014-01-01

    In the Southern French Alps, high sediment yields from marly catchments cause socio-economic and ecological problems downstream. Bioengineering structures made of willow cuttings could be used for efficient and sustainable sediment trapping in eroded gullies in order to decrease sediment yield at their outlets. However, little has been done to quantitatively assess the efficiency of such structures for trapping sediment or to improve their performance. The objectives of this study were to analyze the ability of bioengineering structures to enhance vegetation development and sediment trapping in marly gullies in the Southern French Alps, under a mountainous and Mediterranean climate. For five years after the restoration operations, we monitored 101 bioengineering structures using willow (Salix) cuttings, including 55 brush layers on wooden sills (BL) and 46 brush layers with brush mats on wooden sills (BLM), 1.2 m wide and 2 m long, installed on the floors of eight experimental marly gullies. The results showed that the ultimate survival of willow cuttings can be assessed after three years. Gully size and aspect appeared to be the most important factors influencing resprouting rates. By avoiding south-oriented gullies and those smaller than 1000 m2, 75% survival rates per structure may be achieved. The results also showed that BL trapped 0.18 m3 yr- 1 of sediment per structure on average and BLM 0.21 m3 yr- 1, but potential maximum values may reach 0.28 and 0.40 m3 yr- 1 over one year on BL and BLM, respectively. Therefore, bioengineering structures made of willow cuttings can be used to trap significant quantities of sediment from the first year onwards and efficiently restore eroded marly gullies under a Mediterranean mountainous climate. It also provides design criteria to guide future restoration actions and future investigations in the Southern French Alps.

  5. Lavaka, the unusual gullies of Madagascar: A review for improved data collection

    NASA Astrophysics Data System (ADS)

    Raveloson, Andrea; Szabó, Amanda I.; Ludván, Brigitta; Székely, Balázs

    2015-04-01

    Land degradation in Madagascar is a complex challenge due to the spectacular gullies (called lavaka) that have a number of undesirable effects. These hillslope gullies have been observed for a long time, but the causes of lavakization are still controversial and many questions remain unanswered. Our aim is to assemble and review lavaka researches since 1953 to understand why these didn't lead to success. Exact location of the field surveys, cited triggering factors and results of these scientific papers have been studied in detail. An overview of the many contributing factors is given in order to better understand lavaka formation and distribution. A review is also given on our 3 years work that included the evaluation of lavaka distribution and evolution using satellite images, investigation of the role of the different factors contributing to lavakas formation (concentrating first of all on geology, topography and climatology) and classification done based on earlier studies and satellite images. We conclude that most of the lavaka researches have been achieved along the main roads and therefore are restricted to the middle part of the Malagasy Highland. The study areas designated by different researchers have similar properties in term of soils, climate, and vegetation leading mainly to the same conclusions and although lithology and climatic conditions are mentioned as key factors, their effect on lavaka density and characteristics have not been revealed in details yet. Our studies based on field survey, remote sensing and GIS showed a strong relationship between gully presence, vegetation cover, elevation, relief and slope angle. Geology, soil and precipitation seem to be less important in a medium scales notwithstanding with the fact that many studies dealing with lavaka emphasize their importance in lavakization process. Gully abundance maps showed that lavaka can also occur at lower topographic levels, gentle slopes and sandy sediments notwithstanding with

  6. Distribution of copper and other metals in gully sediments of part of Okanogan County, Washington

    USGS Publications Warehouse

    Fox, Kenneth F.; Rinehart, C. Dean

    1972-01-01

    A geochemical exploration program aimed at determining regional patterns of metal distribution as well as pinpointing areas likely to contain undiscovered ore deposits was carried out in north-central Okanogan County, Washington. About 1,000 gully and stream sediment samples were collected from a rectangular area of about 800 square miles. The area includes two contiguous, virtually dormant, mining districts that had yielded nearly $1.4 million in gold, silver, lead, copper, and zinc prior to the end of World War I, mostly from quartz lodes.

  7. Quantification of gully volume using very high resolution DSM generated through 3D reconstruction from airborne and field digital imagery

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Zarco-Tejada, Pablo; Laredo, Mario; Gómez, Jose Alfonso

    2013-04-01

    Major advances have been made recently in automatic 3D photo-reconstruction techniques using uncalibrated and non-metric cameras (James and Robson, 2012). However, its application on soil conservation studies and landscape feature identification is currently at the outset. The aim of this work is to compare the performance of a remote sensing technique using a digital camera mounted on an airborne platform, with 3D photo-reconstruction, a method already validated for gully erosion assessment purposes (Castillo et al., 2012). A field survey was conducted in November 2012 in a 250 m-long gully located in field crops on a Vertisol in Cordoba (Spain). The airborne campaign was conducted with a 4000x3000 digital camera installed onboard an aircraft flying at 300 m above ground level to acquire 6 cm resolution imagery. A total of 990 images were acquired over the area ensuring a large overlap in the across- and along-track direction of the aircraft. An ortho-mosaic and the digital surface model (DSM) were obtained through automatic aerial triangulation and camera calibration methods. For the field-level photo-reconstruction technique, the gully was divided in several reaches to allow appropriate reconstruction (about 150 pictures taken per reach) and, finally, the resulting point clouds were merged into a unique mesh. A centimetric-accuracy GPS provided a benchmark dataset for gully perimeter and distinguishable reference points in order to allow the assessment of measurement errors of the airborne technique and the georeferenciation of the photo-reconstruction 3D model. The uncertainty on the gully limits definition was explicitly addressed by comparison of several criteria obtained by 3D models (slope and second derivative) with the outer perimeter obtained by the GPS operator identifying visually the change in slope at the top of the gully walls. In this study we discussed the magnitude of planimetric and altimetric errors and the differences observed between the

  8. Making a Bed

    ERIC Educational Resources Information Center

    Wexler, Anthony; Stein, Sherman

    2005-01-01

    The origins of this paper lay in making beds by putting pieces of plywood on a frame: If beds need to be 4 feet 6 inches by 6 feet 3 inches, and plywood comes in 4-foot by 8-foot sheets, how should one cut the plywood to minimize waste (and have stable beds)? The problem is of course generalized.

  9. Use of Activated Charcoal for {sup 220}Rn Adsorption for Operations Associated with the Uranium Deposit in the Auxiliary Charcoal Bed at the Molten Salt Reactor Experiment Facility

    SciTech Connect

    Coleman, R.L.

    1999-03-01

    Measurements have been collected with the purpose of evaluating the effectiveness of activated charcoal for the removal of {sup 220}Rn from process off-gas at the Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory. A series of bench-scale tests were performed at superficial flow velocities of 10, 18, 24, and 33 cm/s (20, 35, 47, and 65 ft/min) with a continuous input concentration of {sup 220}Rn in the range of 9 x 10{sup 3} pCi/L. In addition, two tests were performed at the MSRE facility by flowing helium through the auxiliary charcoal bed uranium deposit. These tests were performed so that the adsorptive effectiveness could be evaluated with a relatively high concentration of {sup 220}Rn. In addition to measuring the effectiveness of activated charcoal as a {sup 220}Rn adsorption media, the source term for available {sup 220}Rn in the deposit is actually available for removal and that the relative activity of fission gases is very small when compared to {sup 220}Rn. The measurement data were then used to evaluate the expected effectiveness of a proposed charcoal adsorption bed consisting of a right circular cylinder having a diameter of 43 cm and a length of 91 cm (17 in. I.D. x 3 ft.). The majority of the measurement data predicts an overall 220Rn activity reduction factor of about 1 x 10{sup 9} for such a design; however, two measurements collected at a flow velocity of 18 cm/s (35 ft/min) indicated that the reduction factor could be as low as 1 x 10{sup 6}. The adsorptive capacity of the proposed trap was also evaluated to determine the expected life prior to degradation of performance. Taking a conservative vantage point during analysis, it was estimated that the adsorption effectiveness should not begin to deteriorate until a {sup 220}Rn activity on the order of 10{sup 10} Ci has been processed. It was therefore concluded that degradation of performance would likely occur as the result of causes other than filling by radon progeny.

  10. Use of Activated Charcoal for Rn-220 Adsorption for Operations Associated with the Uranium Deposit in the Auxiliary Charcoal Bed at the Molten Salt Reactor Experiment Facility

    SciTech Connect

    Coleman, R.L.

    1999-03-17

    Measurements have been collected with the purpose of evaluating the effectiveness of activated charcoal for the removal of {sup 220}Rn from process off-gas at the Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory. A series of bench-scale tests were performed at superficial flow velocities of 10, 18, 24, and 33 cm s{sup -1} (20, 35, 47, and 65 ft min{sup -1}) with a continuous input concentration of {sup 220}Rn in the range of 9 x 10{sup 3} pCi L{sup -1}. In addition, two tests were performed at the MSRE facility by flowing helium through the auxiliary charcoal bed uranium deposit. These tests were performed so that the adsorptive effectiveness could be evaluated with a relatively high concentration of {sup 220}Rn. In addition to measuring the effectiveness of activated charcoal as a {sup 220}Rn adsorption media, the source term for available {sup 220}Rn and gaseous fission products was evaluated and compared to what is believed to be present in the deposit. The results indicate that only a few percent of the total {sup 220}Rn in the deposit is actually available for removal and that the relative activity of fission gases is very small when compared to {sup 220}Rn. The measurement data were then used to evaluate the expected effectiveness of a proposed charcoal adsorption bed consisting of a right circular cylinder having a diameter of 43 cm and a length of 91 cm (17 in. I.D. x 3 ft.). The majority of the measurement data predicts an overall {sup 220}Rn activity reduction factor of about 1 x 10{sup 9} for such a design; however, two measurements collected at a flow velocity of 18 cm s{sup -1} (35 ft min{sup -1}) indicated that the reduction factor could be as low as 1 x 10{sup 6}. The adsorptive capacity of the proposed trap was also evaluated to determine the expected life prior to degradation of performance. Taking a conservative vantage point during analysis, it was estimated that the adsorption effectiveness should not begin to deteriorate

  11. Effects of aquifer storage and recovery activities on water quality in the Little Arkansas River and Equus Beds Aquifer, south-central Kansas, 2011-14

    USGS Publications Warehouse

    Stone, Mandy L.; Garrett, Jessica D.; Poulton, Barry C.; Ziegler, Andrew C.

    2016-07-18

    The Equus Beds aquifer in south-central Kansas is aprimary water source for the city of Wichita. The Equus Beds aquifer storage and recovery (ASR) project was developed to help the city of Wichita meet increasing current (2016) and future water demands. The Equus Beds ASR project pumps water out of the Little Arkansas River during above-base flow conditions, treats it using drinking-water quality standards as a guideline, and recharges it into the Equus Beds aquifer for later use. Phase II of the Equus Beds ASR project currently (2016) includes a river intake facility and a surface-water treatment facility with a 30 million gallon per day capacity. Water diverted from the Little Arkansas River is delivered to an adjacent presedimentation basin for solids removal. Subsequently, waste from the surface-water treatment facility and the presedimentation basin is returned to the Little Arkansas River through a residuals return line. The U.S. Geological Survey, in cooperation with the city of Wichita, developed and implemented a hydrobiological monitoring program as part of the ASR project to characterize and quantify the effects of aquifer storage and recovery activities on the Little Arkansas River and Equus Beds aquifer water quality.Data were collected from 2 surface-water sites (one upstream and one downstream from the residuals return line), 1 residuals return line site, and 2 groundwater well sites (each having a shallow and deep part): the Little Arkansas River upstream from the ASR facility near Sedgwick, Kansas (upstream surface-water site 375350097262800), about 0.03 mile (mi) upstream from the residuals return line site; the Little Arkansas River near Sedgwick, Kans. (downstream surface-water site 07144100), about 1.68 mi downstream from the residuals return line site; discharge from the Little Arkansas River ASR facility near Sedgwick, Kansas (residuals return line site 375348097262800); 25S 01 W 07BCCC01 SMW–S11 near CW36 (MW–7 shallow groundwater well

  12. Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

    PubMed

    Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

    2016-11-01

    In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive. PMID:27501032

  13. Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

    PubMed

    Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

    2016-11-01

    In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive.

  14. Evaluating a strategy for maintaining nitrifier activity during long-term starvation in a moving bed biofilm reactor (MBBR) treating reverse osmosis concentrate.

    PubMed

    Ye, Liu; Hu, Shihu; Poussade, Yvan; Keller, Jurg; Yuan, Zhiguo

    2012-01-01

    A two-stage moving bed biofilm reactor (MBBR) was applied at the Bundamba advanced water treatment plant (AWTP) (Queensland, Australia) to treat the reverse osmosis concentrate (ROC) for inorganic nutrient removal. One of the operational challenges for the system was to cope with the large fluctuations of the ROC flow. This study investigated the decay rates of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) and biofilm detachment in MBBR during starvation for up to one month. An intermittent aeration strategy of 15 min aeration every 6 h was applied. This study also evaluated the activity recovery of both AOB and NOB after normal operation was resumed. The results showed that the activity loss of AOB and NOB was relatively minor (<20%) within 10 days of starvation, which ensured relatively quick recovery of ammonium removal when normal operation resumed. In contrast, the AOB and NOB activity loss reached 60-80% when the starvation time was longer than 20 days, resulting in slower recovery of ammonium removal after starvation. Starvation for less than 20 days didn't result in an apparent biomass detachment from carriers.

  15. Getting Rid of Bed Bugs

    MedlinePlus

    ... Bed Bugs — Do-it-yourself Bed Bug Control — Pesticides to Control Bed Bugs Bed Bug Information Clearinghouse ... Greener Living Health and Safety Land and Cleanup Pesticides Waste Water Science & Technology Air Climate Change Ecosystems ...

  16. Space station propulsion test bed

    NASA Technical Reports Server (NTRS)

    Briley, G. L.; Evans, S. A.

    1989-01-01

    A test bed was fabricated to demonstrate hydrogen/oxygen propulsion technology readiness for the intital operating configuration (IOC) space station application. The test bed propulsion module and computer control system were delivered in December 1985, but activation was delayed until mid-1986 while the propulsion system baseline for the station was reexamined. A new baseline was selected with hydrogen/oxygen thruster modules supplied with gas produced by electrolysis of waste water from the space shuttle and space station. As a result, an electrolysis module was designed, fabricated, and added to the test bed to provide an end-to-end simulation of the baseline system. Subsequent testing of the test bed propulsion and electrolysis modules provided an end-to-end demonstration of the complete space station propulsion system, including thruster hot firings using the oxygen and hydrogen generated from electrolysis of water. Complete autonomous control and operation of all test bed components by the microprocessor control system designed and delivered during the program was demonstrated. The technical readiness of the system is now firmly established.

  17. Treatment of gully pot liquor containing heavy metals with constructed wetlands in Scotland.

    PubMed

    Scholz, M; Anderson, P; Forman, B I

    2005-01-01

    The aim of this investigation was to assess the treatment efficiencies for gully pot liquor of 12 experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) and filter media of different adsorption capacities in a cold climate. Seven of the twelve filters received inflow water spiked with heavy metals. For one year, hydrated copper nitrate and hydrated nickel nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm water runoff. The inflow concentrations for dissolved copper, nickel and nitrate-nitrogen were approximately 1.0, 1.0 and 1.45 mg/l, respectively, which represent mean loading rates of 0.063 g/m2/d for Filters 2 and 7 to 11, and 0.115 g/m2/d for Filter 12. For these filters receiving metals, an obvious breakthrough of dissolved nickel was recorded after road gritting and salting during winter. Sodium chloride was responsible for nickel leaching. Reductions of copper, nickel, biochemical oxygen demand and suspended solids were frequently insufficient compared to international secondary wastewater treatment standards. Moreover, the overall filtration performance for all filters was similar.

  18. [Distribution of micronutrients in soils as affected by landforms in a loessial gully watershed].

    PubMed

    Wei, Xiao-Rong; Shao, Ming-An

    2009-09-15

    Landform is the most important environmental factor influencing the distribution of soil micronutrients in the Loess Plateau and the well understanding of the effects is an important prerequisite for the estimation of soil micronutrients' availability and geochemistry in the Loess Plateau. This study was therefore conducted in a watershed of the loessial gully region to reveal the effects of landforms on profile distribution of soil micronutrients. Soil samples from 37 profiles were collected and total, available and adsorbed iron, manganese, zinc and copper were determined. The results showed that total micronutrients varied slightly with covariance coefficients lower than 15%, while available and adsorbed micronutrients varied greatly in the studied area. Total contents of iron, manganese and copper were higher in gully bottom soils, while total zinc, available and adsorbed micronutrients were higher in plateau land soils compared with soils in other landforms. The soil-forming process and land use conditions in each landform are the major reasons for the differences in soil total micronutrients. Landform induced changes of soil organic matter is the major factor controlling profile distribution of available and adsorbed micronutrients. PMID:19927834

  19. Use of wood-based materials in beef bedded manure packs: 2. Effect on odorous volatile organic compounds, odor activity value, Escherichia coli, and nutrient concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were to determine the effects of three types of wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, and green cedar chips) and corn stover on concentration of odorous volatile organic compounds (VOC) and total Escherichia coli in bedded pack materi...

  20. Early to Bed: A Study of Adaptation among Sexually Active Urban Adolescent Girls Younger than Age Sixteen.

    ERIC Educational Resources Information Center

    Martin, Andres; Ruchkin, Vladislav; Caminis, Argyro; Vermeiren, Robert; Henrich, Christopher C.; Schwab-Stone, Mary

    2005-01-01

    Objective: To examine the association between sexual activity among urban adolescent girls and four global measures of psychosocial adaptation (academic motivation, school achievement, depressive symptoms, and expectations about the future). Method: Data derived from the Social and Health Assessment, a self-report survey administered in 1998 to…

  1. Constraints on mechanisms for the growth of gully alcoves in Gasa crater, Mars, from two-dimensional stability assessments of rock slopes

    USGS Publications Warehouse

    Okubo, C.H.; Tornabene, L.L.; Lanza, N.L.

    2011-01-01

    The value of slope stability analyses for gaining insight into the geologic conditions that would facilitate the growth of gully alcoves on Mars is demonstrated in Gasa crater. Two-dimensional limit equilibrium methods are used in conjunction with high-resolution topography derived from stereo High Resolution Imaging Science Experiment (HiRISE) imagery. These analyses reveal three conditions that may produce observed alcove morphologies through slope failure: (1) a ca >10m thick surface layer that is either saturated with H2O ground ice or contains no groundwater/ice at all, above a zone of melting H2O ice or groundwater and under dynamic loading (i.e., seismicity), (2) a 1-10m thick surface layer that is saturated with either melting H2O ice or groundwater and under dynamic loading, or (3) a >100m thick surface layer that is saturated with either melting H2O ice or groundwater and under static loading. This finding of three plausible scenarios for slope failure demonstrates how the triggering mechanisms and characteristics of future alcove growth would be affected by prevailing environmental conditions. HiRISE images also reveal normal faults and other fractures tangential to the crowns of some gully alcoves that are interpreted to be the result of slope instability, which may facilitate future slope movement. Stability analyses show that the most failure-prone slopes in this area are found in alcoves that are adjacent to crown fractures. Accordingly, crown fractures appear to be a useful indicator of those alcoves that should be monitored for future landslide activity. ?? 2010.

  2. Importance of the operating pH in maintaining the stability of anoxic ammonium oxidation (anammox) activity in moving bed biofilm reactors.

    PubMed

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2011-07-01

    Two bench-scale parallel moving bed biofilm reactors (MBBR) were operated to assess pH-associated anammox activity changes during long term treatment of anaerobically digested sludge centrate pre-treated in a suspended growth partial nitrification reactor. The pH was maintained at 6.5 in reactor R1, while it was allowed to vary naturally between 7.5 and 8.1 in reactor R2. At high nitrogen loads reactor R2 had a 61% lower volumetric specific nitrogen removal rate than reactor R1. The low pH and the associated low free ammonia (FA) concentrations were found to be critical to stable anammox activity in the MBBR. Nitrite enhanced the nitrogen removal rate in the conditions of low pH, all the way up to the investigated level of 50mg NO(2)-N/L. At low FA levels nitrite concentrations up to 250 mg NO(2)-N/L did not cause inactivation of anammox consortia over a 2-days exposure time.

  3. [Optimization of shelterbelt distribution for the gully erosion control of cultivated slope land in rolling hill black soil region of Northeast China].

    PubMed

    Su, Zi-Long; Cui, Ming; Fan, Hao-Ming

    2012-04-01

    Shelterbelt system is one of the main components of cultivated slope land in rolling hill black soil region of Northeast China, which plays an important role in the control of gully erosion. Based on the Quickbird high-resolution remote sensing image and the digital elevation model (DEM), and combining with field survey data, this paper analyzed the effects of shelterbelt system in a small watershed of rolling hill black soil region in Heshan Farm of Heilongjiang Province on the control of gully erosion in the cultivated slope land, and put forward an optimized scheme for gully erosion control based on the features of gully erosion in the cultivated slope land and their relations with the distribution of the shelterbelt system. In the study area, the current distribution of the shelterbelt system promoted the occurrence and development of shallow gully and gully directly and indirectly. The proposed scheme for optimizing the distribution of the present shelterbelts included the adjustment of the direction of the shelterbelt perpendicular to the aspect of slope, the enhancement of the maintenance and regeneration of the shelterbelts to reduce the gaps of the shelterbelts, the increase of the shelterbelt number, and the decrease of the distances between shelterbelts. A method for calculating the shelterbelt number and the distances between the shelterbelts was also given. This study could provide scientific basis for the gully erosion control and the shelterbelts programming in the cultivated slope land of rolling hill black soil region.

  4. The SF3M approach to 3-D photo-reconstruction for non-expert users: application to a gully network

    NASA Astrophysics Data System (ADS)

    Castillo, C.; James, M. R.; Redel-Macías, M. D.; Pérez, R.; Gómez, J. A.

    2015-04-01

    3-D photo-reconstruction (PR) techniques have been successfully used to produce high resolution elevation models for different applications and over different spatial scales. However, innovative approaches are required to overcome some limitations that this technique may present in challenging scenarios. Here, we evaluate SF3M, a new graphical user interface for implementing a complete PR workflow based on freely available software (including external calls to VisualSFM and CloudCompare), in combination with a low-cost survey design for the reconstruction of a several-hundred-meters-long gully network. SF3M provided a semi-automated workflow for 3-D reconstruction requiring ~ 49 h (of which only 17% required operator assistance) for obtaining a final gully network model of > 17 million points over a gully plan area of 4230 m2. We show that a walking itinerary along the gully perimeter using two light-weight automatic cameras (1 s time-lapse mode) and a 6 m-long pole is an efficient method for 3-D monitoring of gullies, at a low cost (about EUR 1000 budget for the field equipment) and time requirements (~ 90 min for image collection). A mean error of 6.9 cm at the ground control points was found, mainly due to model deformations derived from the linear geometry of the gully and residual errors in camera calibration. The straightforward image collection and processing approach can be of great benefit for non-expert users working on gully erosion assessment.

  5. Biophysical and financial impacts of community-based gully rehabilitation in the Birr Watershed, Upper Blue Nile Basin, Ethiopia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although erosion in the Ethiopian highlands has been occurring for thousands of years, rivers sediment concentration has increased two to three fold during the last fifty years, reducing crop and livestock production and the volume of irrigation water stored in reservoirs. Gully erosion in particula...

  6. The economic cost of upland and gully erosion on subsistence agriculture for a watershed in the Ethiopian highlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper quantifies the cost of erosion; it uses nutrient replacement cost to value topsoil nutrient depletion, daily wage rate to monetize the opportunity cost of labour due to gully erosion and local market price to quantify the lost animal and cash crop trees. Soil erosion rate is estimated fro...

  7. Degradation of soil physicochemical quality by ephemeral gully erosion on sloping cropland of the hilly Loess Plateau, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ephemeral gully erosion (EGE) is a common type of shallow linear erosion that exerts a major threat to the productivity and sustainability of agricultural systems. The objective was to evaluate the impact of EGE on soil physicochemical properties that determine soil quality. It was hypothesized that...

  8. An Investigation Into the Potential Role of Carbon Dioxide Sublimation in Linear Gully Pit Formation on Mars

    NASA Astrophysics Data System (ADS)

    Mc Keown, L.; McElwaine, J.; Bourke, M. C.

    2016-09-01

    We present the results of a suite of experiments and image analysis undertaken to test the CO2 sublimation hypothesis, which accounts for linear gully formation via the interaction of sublimating CO2 ice blocks with porous substrate on martian dunes.

  9. Assessing the response of incised coastal gullies to changes in future climate: results from a Monte Carlo modelling approach

    NASA Astrophysics Data System (ADS)

    Hackney, C. R.; Darby, S. E.; Leyland, J.

    2012-12-01

    Numerical models of landscape evolution provide powerful tools to assess the impacts that environmental changes may have on landscape morphology. Under projections of future (next ~100 years) anthropogenic climate change, it is predicted that marked changes in environmental driving conditions, with relation to baseline (1961 - 1990) climates, will be experienced. Herein, a modified version of the CHILD landscape evolution model, capable of modelling coastal erosion, is employed to assess the impacts of anthropogenic climate change on the evolution of a set of incised coastal gullies found on the Isle of Wight, UK. Incised coastal gullies are known to be dynamic and sensitive landscape features which intersect the terrestrial - marine boundary; as such their evolution is influenced by changes in both terrestrial (i.e. precipitation) and maritime (i.e. sea-level and wave height) climates. To explore how these gully features might respond to future climate change, downscaled HadCM3 and CGCM2 Global Climate Model (GCM) outputs for two emissions scenarios (A2 and B2) are used to generate ensemble projections of future precipitation, sea-level and wave height. Comparison against a baseline scenario based on the 1961-1990 climatology allows for climate induced changes in system response to be quantified. To constrain the uncertainties associated with the application of landscape models and downscaled GCM data, a Monte Carlo analysis framework is employed, resulting in 17950 model runs. Results suggest that a shift towards extreme rates of coastal erosion may not be matched by equivalent changes in the rates of headwards erosion, resulting in the loss of incised coastal gully habitat on the Isle of Wight. However, under certain scenarios the possibility of extension of the gully systems exists. Therefore, considerable uncertainty surrounds such predictions, particularly in relation to the emissions scenario and GCM used. In addition, the application of a Monte Carlo

  10. Vasodilator activity of 2-(p-chloro-alpha-hydroxybenzyl)benzimidazole (HBBPC) on femoral vascular bed of the rabbit.

    PubMed

    Demenge, P; Silice, C; Luu Duc, C; Carraz, G

    1979-01-01

    The effects of 2-(p-chloro-alpha-hydroxybenzyl) benzimidazole HCl (HBBPC) have been studied on the femoral peripheral resistance (i.v. route) and only femoral blood flow (local i.a. injection), in comparison with other vasodilators, i.e., sodium nitroprusside, dihydralazine and piribedil. The vasomotor activity of HBBPC, namely, decreased peripheral resistance and increased femoral blood flow, seems interesting because it begins after pressure has returned to normal. This substance is likely to induce a vasoconstriction in other areas (increased femoral blood flow with decreased peripheral resistance without a fall of blood pressure).

  11. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  12. Fluidized bed combustion

    SciTech Connect

    Sowards, N.K.; Murphy, M.L.

    1991-10-29

    This patent describes a vessel. It comprises a fluid bed for continuously incinerating fuel comprising tire segments and the like which comprise metallic wire tramp and for concurrently removing tramp and bed materials at a bottom effluent exit means of the vessel, the vessel further comprising static air distributor means at the periphery of the bed comprising a substantially centrally unobstructed relatively large central region in which the fluid bed and fuel only are disposed and through which bed material and tramp migrate without obstruction to and through the effluent exit means, downwardly and inwardly stepped lower vessel wall means and a plurality of peripherally located centrally directed vertically and horizontally offset spaced air influent means surrounding the central region and associated with the stepped lower vessel wall means by which the bed is supported and fluidized.

  13. Updated Performance Evaluation of the ISS Water Processor Multifiltration Beds

    NASA Technical Reports Server (NTRS)

    Bowman, Elizabeth M.; Carter, Layne; Carpenter, Joyce; Orozco, Nicole; Weir, Natalee; Wilson, Mark

    2014-01-01

    The ISS Water Processor Assembly (WPA) produces potable water from a waste stream containing humidity condensate and urine distillate. The primary treatment process is achieved in the Multifiltration Beds, which include adsorbent media and ion exchange resin for the removal of dissolved organic and inorganic contaminants. Two Multifiltration Beds (MF Beds) were replaced on ISS in July 2010 after initial indication of inorganic breakthrough of the first bed and an increasing Total Organic Carbon (TOC) trend in the product water. The first bed was sampled and analyzed Sept 2011 through March 2012. The second MF Bed was sampled and analyzed June 2012 through August 2012. The water resident in the both beds was analyzed for various parameters to evaluate adsorbent loading, performance of the ion exchange resin, microbial activity, and generation of leachates from the ion exchange resin. Portions of the adsorbent media and ion exchange resin were sampled and subsequently desorbed to identify the primary contaminants removed at various points in the bed in addition to microbial analysis. Analysis of the second bed will be compared to results from the first bed to provide a comprehensive overview of how the Multifiltration Beds function on orbit. New data from the second bed supplements the analysis of the first bed (previously reported) and gives a more complete picture of breakthrough compounds, resin breakdown products, microbial activity, and difficult to remove compounds. The results of these investigations and implications to the operation of the WPA on ISS are documented in this paper.

  14. Pituitary adenylyl cyclase activating peptide (PACAP) in the bed nucleus of the stria terminalis (BNST) increases corticosterone in male and female rats

    PubMed Central

    Lezak, K. R.; Roelke, E.; Harris, O.; Choi, I.; Edwards, S.; Gick, N.; Cocchiaro, G.; Missig, G.; Roman, C. W.; Braas, K. M.; Toufexis, D.J.; May, V.; Hammack, S. E.

    2014-01-01

    Single nucleotide polymorphisms (SNP) in the genes for pituitary adenylate cyclase-activating peptide (PACAP) and the PAC1 receptor have been associated with several psychiatric disorders whose etiology has been associated with stressor exposure and/or dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. In rats, exposure to repeated variate stress has been shown to increase PACAP and its cognate PAC1 receptor expression in the bed nucleus of the stria terminalis (BNST), a brain region implicated in anxiety and depression-related behaviors as well as the regulation of HPA axis activity. We have argued that changes in BNST PACAP signaling may mediate the changes in emotional behavior and dysregulation of the HPA axis associated with anxiety and mood disorders. The current set of studies was designed to determine whether BNST PACAP infusion leads to activation of the HPA axis as determined by increases in plasma corticosterone. We observed an increase in plasma corticosterone levels 30 minutes following BNST PACAP38 infusion in male and female rats, which was independent of estradiol (E2) treatment in females, and we found that plasma corticosterone levels were increased at both 30 minutes and 60 minutes, but returned to baseline levels 4 hours following the highest dose. PACAP38 infusion into the lateral ventricles immediately above the BNST did not alter plasma corticosterone level, and the increased plasma corticosterone following BNST PACAP was not blocked by BNST corticotropin releasing hormone (CRH) receptor antagonism. These results support others suggesting that BNST PACAP plays a key role in regulating stress responses. PMID:24845172

  15. Biodegradation of wastewater pollutants by activated sludge encapsulated inside calcium-alginate beads in a tubular packed bed reactor.

    PubMed

    Sergio, A Martinez D; Bustos, T Yaneth

    2009-09-01

    The wastewater treatment plants produce large quantities of biomass (sludge) that require about one-third of the total inversion and operation plant costs for their treatment. By the microorganisms immobilization it is possible to handle high cell concentration in the reactor, increasing its efficiency, reducing the loss of biomass and the wash out is avoided. Moreover, there is no cell growth then the sludge production is reduced. In this study, the COD removal and VSS variation were modeled in a tubular reactor with activated sludge immobilized in Ca-alginate. Moreover, two aspects that are commonly not considered in the performance of the actual reactors of this kind were introduced; the performance in non-steady state and the dispersion effect. The model was calibrated with an actual wastewater taken out from a Mexican wastewater treatment plant. The results of the performance of the tubular bioreactor at different scenarios (i.e., different residence time and VSS in the reactor) are presented. With longer residence times and higher VSS concentration in the Ca-alginate beads in the tubular bioreactor it is possible to increase the time operation of the bioreactor and to treat higher volumes of wastewater. During the process, the sludge generation was drastically reduced and it is possible to remove nitrogen form the wastewater making this process more attractive.

  16. A semi-active milling procedure in view of preparing implantation beds in robot-assisted orthopaedic surgery.

    PubMed

    Van Ham, G; Denis, K; Vander Sloten, J; Van Audekercke, R; Van der Perre, G; De Schutter, J; Simon, J P; Fabry, G

    2005-05-01

    Bone cutting in total joint reconstructions requires a high accuracy to obtain a well-functioning and long-lasting prosthesis. Hence robot assistance can be useful to increase the precision of the surgical actions. A drawback of current robot systems is that they autonomously machine the bone, in that way ignoring the surgeon's experience and introducing a safety risk. This paper presents a semi-active milling procedure to overcome that drawback. In this procedure the surgeon controls robot motion by exerting forces on a force-controlled lever that is attached to the robot end effector. Meanwhile the robot constrains tool motion to the planned motion and generates a tool feed determined by the feed force that the surgeon executes. As a case study the presented milling procedure has been implemented on a laboratory set-up for robot-assisted preparation of the acetabulum in total hip arthroplasty. Two machining methods have been considered. In the first method the surgeon determines both milling trajectory and feed by the forces that he/she executes on the force-controlled lever. In the second method the cavity is machined contour by contour, and the surgeon only provides the feed. Machining experiments have shown that the first method results in large surface irregularities and is not useful. The second method, however, results in accurate cavity preparation and has therefore potential to be implemented in future robot systems.

  17. Effect of pH, empty bed contact time and hydraulic loading rate on lead removal by granular activated carbon columns

    SciTech Connect

    Reed, B.E.; Jamil, M.; Thomas, B.

    1996-07-01

    Batch and column studies were performed to determine the effect of pH, empty bed contact time (EBCT), and hydraulic loading rate (HLR) on lead removal by granular activated carbon (GAC) columns. Lead removal increased with increasing pH, and for the majority of the adsorbate:adsorbent ratios investigated, was 100% as pHs < pH{sub prec}. Column pH was extremely important to lead removal in GAC columns. A simple acid-base regeneration procedure was found to be effective in desorbing/resolubilizing the carbon-bound lead and raising the pH for the subsequent treatment run. Regeneration efficiencies were often less than 100%, but column performance was not adversely affected. For 1 mg/L lead, the optimum EBCT was between 6 and 7 minutes, Whereas for 10 mg/L lead it was less than 10 minutes. The effect of HLR (4.9 and 9.8 m/hr) on column performance was minimal for 1 mg/L lead, whereas at 10 mg/L lead column removal was slightly better at the higher HLR. Carbon usage rates were higher than those observed for wastewaters containing organic contaminants, especially at 10 mg/L lead. However, given the relatively simple regeneration scheme, the applicability of GAC columns for metal-bearing wastewaters appears to be technically feasible. 8 refs., 7 figs., 3 tabs.

  18. Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank SX-105 And AN-103) By Fluidized Bed Steam Reformation

    SciTech Connect

    Jantzen, Carol; Herman, Connie; Crawford, Charles; Bannochie, Christopher; Burket, Paul; Daniel, Gene; Cozzi, Alex; Nash, Charles; Miller, Donald; Missimer, David

    2014-01-10

    One of the immobilization technologies under consideration as a Supplemental Treatment for Hanford’s Low Activity Waste (LAW) is Fluidized Bed Steam Reforming (FBSR). The FBSR technology forms a mineral waste form at moderate processing temperatures thus retaining and atomically bonding the halides, sulfates, and technetium in the mineral phases (nepheline, sodalite, nosean, carnegieite). Additions of kaolin clay are used instead of glass formers and the minerals formed by the FBSR technology offers (1) atomic bonding of the radionuclides and constituents of concern (COC) comparable to glass, (2) short and long term durability comparable to glass, (3) disposal volumes comparable to glass, and (4) higher Na2O and SO{sub 4} waste loadings than glass. The higher FBSR Na{sub 2}O and SO{sub 4} waste loadings contribute to the low disposal volumes but also provide for more rapid processing of the LAW. Recent FBSR processing and testing of Hanford radioactive LAW (Tank SX-105 and AN-103) waste is reported and compared to previous radioactive and non-radioactive LAW processing and testing.

  19. Validating the colloid model to optimise the design and operation of both moving-bed biofilm reactor and integrated fixed-film activated sludge systems.

    PubMed

    Albizuri, J; Grau, P; Christensson, M; Larrea, L

    2014-01-01

    The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m(2)d) was obtained at 10 °C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification-nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m(2)d)) is half of that in tertiary nitrification due to the effect of influent colloidal XS (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m(2)d)) is 20% higher than for the pure MBBR due to the lower effect of influent XS since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days.

  20. Validating the colloid model to optimise the design and operation of both moving-bed biofilm reactor and integrated fixed-film activated sludge systems.

    PubMed

    Albizuri, J; Grau, P; Christensson, M; Larrea, L

    2014-01-01

    The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m(2)d) was obtained at 10 °C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification-nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m(2)d)) is half of that in tertiary nitrification due to the effect of influent colloidal XS (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m(2)d)) is 20% higher than for the pure MBBR due to the lower effect of influent XS since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days. PMID:24718350

  1. Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Water is the chief agent of weathering and erosion on Earth. Mars is a much drier, colder planet on which liquid water cannot exist very long at the surface because it will immediately begin to boil, evaporate, and freeze--all at the same time. However, new pictures from the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) have provided an astonishing observation which suggests that liquid water may have played a role in shaping some recent gully-like features found on the slopes of various craters, troughs, and other depressions on the red planet.

    These pictures introduce the basic features of a martian gully. The figure on the left is an example from Mars, the figure on the right is a gully on Earth. In the Earth picture, rain water flowing under and seeping along the base of a recently-deposited volcanic ash layer has created the gully. For Mars, water is not actually seen but is inferred from the landforms and their similarity to examples on Earth.

    The landforms both on Earth and Mars are divided into three parts: the alcove, the channel, and the apron. Water seeps from between layers of rock on the wall of a cliff, crater, or other type of depression. The alcove forms above the site of seepage as water comes out of the ground and undermines the material from which it is seeping. The erosion of material at the site of seepage causes rock and debris on the slope above this area to collapse and slide downhill, creating the alcove.

    The channel forms from water and debris running down the slope from the seepage area. The point where the top of the channel meets the bottom of the alcove is, in many cases, the site where seepage is occurring. Channels are probably flushed-clean of debris from time to time by large flash floods of water released from behind an ice barrier that might form at the site of seepage during more quiescent times.

    The aprons are the down-slope deposits of ice and debris that were moved down the slope and through

  2. Submarine canyons as important habitat for cetaceans, with special reference to the Gully: A review

    NASA Astrophysics Data System (ADS)

    Moors-Murphy, Hilary B.

    2014-06-01

    There has been much research interest in the use of submarine canyons by cetaceans, particularly beaked whales (family Ziphiidae), which appear to be especially attracted to canyon habitats in some areas. However, not all submarine canyons are associated with large numbers of cetaceans and the mechanisms through which submarine canyons may attract cetaceans are not clearly understood. This paper reviews some of the cetacean associations with submarine canyons that have been anecdotally described or presented in scientific literature and discusses the physical, oceanographic and biological mechanisms that may lead to enhanced cetacean abundance around these canyons. Particular attention is paid to the Gully, a large submarine canyon and Marine Protected Area off eastern Canada for which there exists some of the strongest evidence available for submarine canyons as important cetacean habitat. Studies demonstrating increased cetacean abundance in the Gully and the processes that are likely to attract cetaceans to this relatively well-studied canyon are discussed. This review provides some limited evidence that cetaceans are more likely to associate with larger canyons; however, further studies are needed to fully understand the relationship between the physical characteristics of canyons and enhanced cetacean abundance. In general, toothed whales (especially beaked whales and sperm whales) appear to exhibit the strongest associations with submarine canyons, occurring in these features throughout the year and likely attracted by concentrating and aggregating processes. By contrast, baleen whales tend to occur in canyons seasonally and are most likely attracted to canyons by enrichment and concentrating processes. Existing evidence thus suggests that at least some submarine canyons are important foraging areas for cetaceans, and should be given special consideration for cetacean conservation and protection.

  3. Effects of aquifer storage and recovery activities on water quality in the Little Arkansas River and Equus Beds Aquifer, south-central Kansas, 2011-14

    USGS Publications Warehouse

    Stone, Mandy L.; Garrett, Jessica D.; Poulton, Barry C.; Ziegler, Andrew C.

    2016-07-18

    The Equus Beds aquifer in south-central Kansas is aprimary water source for the city of Wichita. The Equus Beds aquifer storage and recovery (ASR) project was developed to help the city of Wichita meet increasing current (2016) and future water demands. The Equus Beds ASR project pumps water out of the Little Arkansas River during above-base flow conditions, treats it using drinking-water quality standards as a guideline, and recharges it into the Equus Beds aquifer for later use. Phase II of the Equus Beds ASR project currently (2016) includes a river intake facility and a surface-water treatment facility with a 30 million gallon per day capacity. Water diverted from the Little Arkansas River is delivered to an adjacent presedimentation basin for solids removal. Subsequently, waste from the surface-water treatment facility and the presedimentation basin is returned to the Little Arkansas River through a residuals return line. The U.S. Geological Survey, in cooperation with the city of Wichita, developed and implemented a hydrobiological monitoring program as part of the ASR project to characterize and quantify the effects of aquifer storage and recovery activities on the Little Arkansas River and Equus Beds aquifer water quality.Data were collected from 2 surface-water sites (one upstream and one downstream from the residuals return line), 1 residuals return line site, and 2 groundwater well sites (each having a shallow and deep part): the Little Arkansas River upstream from the ASR facility near Sedgwick, Kansas (upstream surface-water site 375350097262800), about 0.03 mile (mi) upstream from the residuals return line site; the Little Arkansas River near Sedgwick, Kans. (downstream surface-water site 07144100), about 1.68 mi downstream from the residuals return line site; discharge from the Little Arkansas River ASR facility near Sedgwick, Kansas (residuals return line site 375348097262800); 25S 01 W 07BCCC01 SMW–S11 near CW36 (MW–7 shallow groundwater well

  4. Channel Morphology and Bed Sediment Characteristics Before and After Habitat Enhancement Activities in the Uridil Property, Platte River, Nebraska, Water Years 2005-2008

    USGS Publications Warehouse

    Kinzel, Paul J.

    2009-01-01

    Fluvial geomorphic data were collected by the United States Geological Survey from July 2005 to June 2008 (a time period within water years 2005 to 2008) to monitor the effects of habitat enhancement activities conducted in the Platte River Whooping Crane Maintenance Trust's Uridil Property, located along the Platte River, Nebraska. The activities involved the removal of vegetation and sand from the tops of high permanent islands and the placement of the sand into the active river channel. This strategy was intended to enhance habitat for migratory water birds by lowering the elevations of the high islands, thereby eliminating a visual obstruction for roosting birds. It was also thought that the bare sand on the lowered island surfaces could serve as potential habitat for nesting water birds. Lastly, the project supplied a local source of sediment to the river to test the hypothesis that this material could contribute to the formation of lower sandbars and potential nesting sites downstream. Topographic surveys on the islands and along river transects were used to quantify the volume of removed sand and track the storage and movement of the introduced sand downstream. Sediment samples were also collected to map the spatial distribution of river bed sediment sizes before and after the management activities. While the project lowered the elevation of high islands, observations of the sand addition indicated the relatively fine-grained sand that was placed in the active river channel was rapidly transported by the flowing water. Topographic measurements made 3 months after the sand addition along transects in the area of sediment addition showed net aggradation over measurements made in 2005. In the year following the sand addition, 2007, elevated river flows from local rain events generally were accompanied by net degradation along transects within the area of sediment addition. In the spring of 2008, a large magnitude flow event of approximately 360 cubic meters per

  5. Fluidized bed calciner apparatus

    DOEpatents

    Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

    1988-01-01

    An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.

  6. Aggradation and Degradation of the Palisades Gully Network, 1996 to 2005, with Emphasis on the November 2004 High-Flow Experiment, Grand Canyon National Park, Arizona

    USGS Publications Warehouse

    Hazel, Joseph E.; Kaplinski, Matt; Parnell, Roderic A.; Fairley, Helen C.

    2008-01-01

    This study examines a large drainage network incised into alluvial terraces located along the Colorado River downstream of Palisades Creek in Grand Canyon National Park, Ariz. Gully erosion in the drainage affects archaeological sites found on the wide, relatively flat alluvial terraces. In 1996, 7-d release of 1,274 cubic meters per second of water from Glen Canyon Dam, known as a controlled flood, deposited fine-grained sediment - sand, silt, and clay - in the mouth of the network's largest gully, informally known as south gully. The deposit persisted for several years, but the drainage network steepened in the downstream reaches between 1999 and 2004. A high-flow experiment similar to the 1996 controlled flood was conducted in November 2004. The 2004 experiment was of a lower magnitude and shorter duration compared to the 1996 controlled flood. Topographic surveys were made in the field before, immediately after, and 6 months following the November 2004 experiment, and these measurements were compared to those made in 1996 and in other years. Similar to the response in 1996, fine-grained sediment was deposited in the mouth of the south gully and this mass was largely retained during the 6 months following the 2004 event. The magnitude of deposition in 2004 was nearly two times greater than that resulting from the 1996 controlled flood. We attribute this marked difference to increased accommodation space for deposition in the gully mouth, which was more deeply eroded in 2004 than it was in 1996. The second of the two primary gullies found within the Palisades gully network, the north gully, was largely unaffected by either high flow. Between 1996 and 2005, erosion was primarily confined to the lower reach of the south gully, while the upper reach remained relatively stable. The available data suggest that local base-level changes in the south gully mouth were not linked to the stability of the upstream gully reach. It could not be determined whether temporary

  7. How does gully recharge affect sediment transfers by debris flows? A numerical modelling study in steep mountainous terrain, coastal British Columbia

    NASA Astrophysics Data System (ADS)

    Martin, Y. E.; Johnson, E. A.; Chaikina, O.

    2014-12-01

    Debris flows are a major process responsible for transferring sediment from high mountain locations to more downstream fluvial reaches. This sediment transfer begins on mountain hillslopes where various mass wasting processes move sediment from hillslopes to uppermost reaches of the channel system (these reaches are herein referred to as gullies and only experience water flow during high intensity precipitation events). Sediment recharge into gullies, which has received minimal attention in the scientific literature, refers to the transfer of sediment and other debris from surrounding hillslopes into gullies (Jakob and Oden, 2005). Debris flow occurrence and debris flow volumes depend on some precipitation threshold as well as volumes of material contained in the particular gully. For example, if one debris flow has removed all of the accumulated material from the gully, then any subsequent debris flow will be smaller if enough time has not yet passed for notable sediment recharge. Herein, we utilize the numerical model of landscape development, LandMod (Martin, 1998; Dadson and Church, 2005; Martin, 2007), to explore connections between hillslope processes, gully recharge rates, and transfer of sediment to downstream channel reaches in the Haida Gwaii, British Columbia. Hillslope processes in the model include shallow landsliding, bedrock failures and weathering. The updated debris flow algorithm is based on extensive field data available for debris flows in Haida Gwaii (e.g., Rood, 1984; Oden, 1994; Jakob and Oden, 2005), as well as theoretical considerations based on debris flow studies. The most significant model extension is the calculation of gully recharge rates; for each gully, the total accumulated sediment in gullies at each time step is determined using a power-law relation for area-normalized recharge rate versus elapsed time since the last debris flow. Thus, when the stochastic driver for debris flow occurrence triggers an event, the amount of stored

  8. Legacies in urban stormwater management and the effect on gully formation in a Piedmont region of the US Mid Atlantic

    NASA Astrophysics Data System (ADS)

    Claessens, L.; Wehner, C. E.; Santangelo, T.; Soroka, A.

    2013-12-01

    Impervious surfaces in urban areas lead to increased stormwater runoff and produce flashier hydrology which can lead to stream bank erosion and increased sediment delivery to downstream ecosystems. Since the early 1990s the EPA has enforced stormwater regulation and nowadays, practices must be implemented that minimize water quality impacts. However, legacies of stormwater management in pre-regulated areas could be an important factor in the degradation of water quality. From a larger watershed perspective there is therefore a disconnect between investments in newly developed areas where water quality deterioration is perhaps minor vs. minimal investments in pre-regulation areas where water quality deterioration is perhaps major. In this study we examine such legacies in urban stormwater management and the effect on gully formation, with the objective to identify hotspots of water quality degradation and optimal locations for reducing water quality impacts. Our research primarily focuses on older developments (pre-1990s) in the Piedmont region of the Christina River basin (CRB), a tributary of the Delaware River. Many of the streams in the CRB have impaired water quality. We used a combination of methodological approaches, including historical surveys (aerial imagery, land-use maps, stormwater design reports), field observations (WQ sampling, topographic surveys), hydrological modeling, and geospatial analysis. We developed a simple GIS-based model that predicts susceptibility for gully erosion. The model calculates runoff (using Curve Number method), performs hydrologic routing, and based on topographic indices it estimates gully susceptibility for stream reaches draining urban developments. Our results show that the gully susceptibility model produces accurate predictions, including the location of deeply incised gullies. Through geospatial analysis we also identify benefits of structural stormwater control measures and BMPs, and the role of spatial variable land

  9. Preference for bedding material in Syrian hamsters.

    PubMed

    Lanteigne, M; Reebs, S G

    2006-10-01

    This study aimed to determine whether Syrian (golden) hamsters, Mesocricetus auratus, prefer certain bedding materials and whether bedding material can affect paw condition, body weight gain and wheel-running activity. In a first experiment, 26 male hamsters had access to two connected cages, each cage containing a different bedding material (either pine shavings, aspen shavings, corn cob or wood pellets). In a second experiment, 14 male hamsters had access to four connected cages that contained the different bedding materials and also a piece of paper towel to serve as nest material. In a third experiment, 30 male hamsters were each placed in a single cage, 10 of them with pine shavings, 10 with aspen shavings and 10 with corn cob, and they were monitored for 50 days. Significant preferences in the first experiment were: pine shavings over aspen shavings, corn cob over wood pellets, pine shavings over corn cob and aspen shavings over wood pellets (aspen shavings versus corn cob was not tested). However, there was no significant preference expressed in the second experiment, suggesting that the general preference for shavings in the first experiment was based on bedding material suitability as a nesting material. No significant effect of bedding material on paw condition, body weight gain and wheel-running activity was detected. None of the four bedding materials tested in this study can be judged to be inappropriate in the short term if nesting material is added to the cage and if the litter is changed regularly. PMID:17018212

  10. Bathing a patient in bed

    MedlinePlus

    Bed bath; Sponge bath ... Some patients cannot safely leave their beds to bathe. For these people, daily bed baths can help keep their skin healthy, control odor, and increase comfort. If moving the ...

  11. The use of very high resolution DSMs for the investigation of gully evolution in the Souss Basin, Morocco derived from UAV missions

    NASA Astrophysics Data System (ADS)

    d'Oleire-Oltmanns, S.; Marzolff, I.; Schrott, L.

    2012-04-01

    For the analysis of gullies as one type of landform this work presents an approach using small format aerial photographs derived from field campaigns with an unmanned aerial vehicle (UAV) in the Souss Basin, Morocco. Since many existing gullies are neighboring agro-industrial as well as settlement areas the investigation of current gully development is important. We used aerial photographs to create Digital Surface Models (DSMs) which allows detailed analysis of gully development. Depending on the flying height DSMs resolution ranges between a few centimeters and approx. 0.5 m. Challenges and uncertainties relate to mismatches of objects such as vegetation (i.e. bushes, trees) and built-up areas (i.e. greenhouses). The analysis of high resolution DSMs allows also the identification of specific geomorphological properties of gullies. Identifying unique landform properties may then allow the transfer of those properties onto satellite data. This in turn enables object-based image analysis on large-scale gully distribution. This is necessary to provide the greater spatial context within the study area.

  12. Development and application of an actively controlled hybrid proton exchange membrane fuel cell-Lithium-ion battery laboratory test-bed based on off-the-shelf components

    NASA Astrophysics Data System (ADS)

    Yufit, V.; Brandon, N. P.

    The use of commercially available components enables rapid prototyping and assembling of laboratory scale hybrid test-bed systems, which can be used to evaluate new hybrid configurations. The development of such a test-bed using an off-the-shelf PEM fuel cell, lithium-ion battery and DC/DC converter is presented here, and its application to a hybrid configuration appropriate for an unmanned underwater vehicle is explored. A control algorithm was implemented to regulate the power share between the fuel cell and the battery with a graphical interface to control, record and analyze the electrochemical and thermal parameters of the system. The results demonstrate the applicability of the test-bed and control algorithm for this application, and provide data on the dynamic electrical and thermal behaviour of the hybrid system.

  13. Bed occupancy by diabetic patients.

    PubMed

    Moffitt, P; Fowler, J; Eather, G

    1979-03-24

    The Royal Newcastle Hospital Diabetic Education and Stabilization Centre was instituted primarily to improve diabetics' understanding of their disease and its everyday management. Simultaneously with a five-day education course, stabilization if insulin-dependent diabetics was undertaken on an outpatient basis. In order to disseminate diabetic education as widely as possible, trained nurses from near and far were included in each course. It is believed that these nurses will be able to offer good advice to diabetics who have no other source of reliable information. By actively attempting to reduce hospital bed occupancy by diabetics there has been a reduction of 1400 bed days per year. It is recommended that similar centres be instituted throughout Australia.

  14. Effect of 3-Day Bed Rest on the Basal Sympathetic Activity and Responsiveness of this System to Physiological Stimuli In Athletes and Sedentary Subjects

    NASA Technical Reports Server (NTRS)

    Smorawinski, Jerzy; Adrian, Jacek; Kaciuba-Uscilko, Hanna; Nazar, Krystyna; Greenleaf, John E.; Dalton, P. Bonnie (Technical Monitor)

    2002-01-01

    The aims of this study were: (1) to examine the effect of three days of bed rest (BR) on basal plasma epinephrine [E] and norepinephrine [NE] and the catecholamine responses to various physiological stimuli, and (2) to find out whether previous physical activity modifies effects of BR. In the first series, 29 young men (11 sedentary students, 8 endurance and 10 strength trained athletes) were submitted to oral glucose tolerance test in supine position and to active orthostatic test before and after 3 days of BR. Plasma [E] and [NE] were measured after overnight fast (basal condition), at 60, 120 and 180 min after glucose ingestion (70 a), and at the 8th min of unsupported standing. In the second series, other 22 subjects (12 sedentary students, 10 endurance and 10 strength trained athletes) were submitted to 2 min cold pressor test (CPT) and exercise. Plasma E and NE were determined in the supine position after overnight fast and at 60th and 120th s of hand cooling. Then, after breakfast followed by 2-3 hour sitting, the subjects performed cycle ergometer exercise with workload increasing until volitional exhaustion. Plasma [E] and [NE] were determined at the end of each load. Plasma catecholamines were determined made radioenzymatically. After BR, basal plasma [NE] was decreased in endurance and strength athletes (p<0.01) but not in sedentary subjects. In neither group BR affected the basal [E]. Responses of both catecholamines to glucose load were diminished after BR in all three groups (p<0.05) but the effect was most pronounced in the endurance athletes. All subjects tolerated well 8-min standing although their heart rate response was increased after BR. Plasma catecholamine responses standing were not significantly affected by BR in either group but the plasma [NE] and [E] during standing were lowered after BR in endurance athletes (p<0.01). BR did not affect blood pressure and catecholamine responses to CPT. The pre- and post-exercise plasma catecholamines

  15. Monitoring and assessment of treated river, rain, gully pot and grey waters for irrigation of Capsicum annuum.

    PubMed

    Al-Isawi, Rawaa H K; Almuktar, Suhad A A A N; Scholz, Miklas

    2016-05-01

    This study examines the benefits and risks associated with various types of wastewater recycled for vegetable garden irrigation and proposes the best water source in terms of its water quality impact on crop yields. The aim was to evaluate the usability of river, rain, gully pot, real grey and artificial grey waters to water crops. The objectives were to evaluate variables and boundary conditions influencing the growth of chillies (De Cayenne; Capsicum annuum (Linnaeus) Longum Group 'De Cayenne') both in the laboratory and in the greenhouse. A few irrigated chilli plants suffered from excess of some nutrients, which led to a relatively poor harvest. High levels of trace minerals and heavy metals were detected in river water, gully pot effluent and greywater. However, no significant differences in plant yields were observed, if compared with standards and other yields worldwide. The highest yields were associated with river water both in the laboratory and in the greenhouse. Plant productivity was unaffected by water quality due to the high manganese, potassium, cadmium and copper levels of the greywater. These results indicate the potential of river water and gully pot effluent as viable alternatives to potable water for irrigation in agriculture.

  16. Monitoring and assessment of treated river, rain, gully pot and grey waters for irrigation of Capsicum annuum.

    PubMed

    Al-Isawi, Rawaa H K; Almuktar, Suhad A A A N; Scholz, Miklas

    2016-05-01

    This study examines the benefits and risks associated with various types of wastewater recycled for vegetable garden irrigation and proposes the best water source in terms of its water quality impact on crop yields. The aim was to evaluate the usability of river, rain, gully pot, real grey and artificial grey waters to water crops. The objectives were to evaluate variables and boundary conditions influencing the growth of chillies (De Cayenne; Capsicum annuum (Linnaeus) Longum Group 'De Cayenne') both in the laboratory and in the greenhouse. A few irrigated chilli plants suffered from excess of some nutrients, which led to a relatively poor harvest. High levels of trace minerals and heavy metals were detected in river water, gully pot effluent and greywater. However, no significant differences in plant yields were observed, if compared with standards and other yields worldwide. The highest yields were associated with river water both in the laboratory and in the greenhouse. Plant productivity was unaffected by water quality due to the high manganese, potassium, cadmium and copper levels of the greywater. These results indicate the potential of river water and gully pot effluent as viable alternatives to potable water for irrigation in agriculture. PMID:27075312

  17. Test Bed For Telerobots

    NASA Technical Reports Server (NTRS)

    Matijevic, Jacob R.; Zimmerman, Wayne F.; Dolinsky, Shlomo

    1990-01-01

    Assembly of electromechanical and electronic equipment (including computers) constitutes test bed for development of advanced robotic systems for remote manipulation. Combines features not found in commercial systems. Its architecture allows easy growth in complexity and level of automation. System national resource for validation of new telerobotic technology. Intended primarily for robots used in outer space, test bed adapted to development of advanced terrestrial telerobotic systems for handling radioactive materials, dangerous chemicals, and explosives.

  18. Bed rest and immunity

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Gerald; Aviles, Hernan; Butel, Janet S.; Shearer, William T.; Niesel, David; Pandya, Utpal; Allen, Christopher; Ochs, Hans D.; Blancher, Antoine; Abbal, Michel

    2007-02-01

    Space flight has been shown to result in altered immune responses. The current study was designed to investigate this possibility by using the bed rest model of some space flight conditions. A large number of women are included as subjects in the study. The hypothesis being tested is: 60 days head-down tilt bed rest of humans will affect the immune system and resistance to infection. Blood, urine and saliva samples will be obtained from bed rest subjects prior to, at intervals during, and after completion of 60 days of head-down tilt bed rest. Leukocyte blastogenesis, cytokine production and virus reactivation will be assessed. The ability of the subjects to respond appropriately to immunization with the neoantigen bacteriophage φX-174 will also be determined. Bed rest is being carried out at MEDES, Toulouse France, and the University of Texas Medical Branch, Galveston, TX. The studies to be carried out in France will also allow assessment of the effects of muscle/bone exercise and nutritional countermeasures on the immune system in addition to the effects of bed rest.

  19. Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site]

    Gullies eroded into the wall of a meteor impact crater in Noachis Terra. This high resolution view (top left) from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows channels and associated aprons of debris that are interpreted to have formed by groundwater seepage, surface runoff, and debris flow. The lack of small craters superimposed on the channels and apron deposits indicates that these features are geologically young. It is possible that these gullies indicate that liquid water is present within the martian subsurface today.

    The MOC image was acquired on September 28, 1999. The scene covers an area approximately 3 kilometers (1.9 miles) wide by 6.7 km (4.1 mi) high (note, the aspect ratio is 1.5 to 1.0). Sunlight illuminates this area from the upper left. The image is located near 54.8oS, 342.5oW. The context image (above) shows the location of the MOC image on the south-facing wall of an impact crater approximately 20 kilometers (12 miles) in diameter. The context picture was obtained by the Viking 1 orbiter in 1980 and is illuminated from the upper left. The large mound on the floor of the crater in the context view is a sand dune field. The Mars Orbiter Camera high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.

    A brief description of how the color was generated: The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallette of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to

  20. Salmon-driven bed load transport and bed morphology in mountain streams

    NASA Astrophysics Data System (ADS)

    Hassan, Marwan A.; Gottesfeld, Allen S.; Montgomery, David R.; Tunnicliffe, Jon F.; Clarke, Garry K. C.; Wynn, Graeme; Jones-Cox, Hale; Poirier, Ronald; MacIsaac, Erland; Herunter, Herb; Macdonald, Steve J.

    2008-02-01

    Analyses of bed load transport data from four streams in British Columbia show that the activity of mass spawning salmon moved an average of almost half of the annual bed load yield. Spawning-generated changes in bed surface topography persisted from August through May due to lack of floods during the winter season, defining the bed surface morphology for most of the year. Hence, salmon-driven bed load transport can substantially influence total sediment transport rates, and alter typical alluvial reach morphology. The finding that mass-spawning fish can dominate sediment transport in mountain drainage basins has fundamental implications for understanding controls on channel morphology and aquatic ecosystem dynamics, as well as stream responses to environmental change and designing river restoration programs for channels that have, or historically had large spawning runs.

  1. Control of bed height in a fluidized bed gasification system

    DOEpatents

    Mehta, Gautam I.; Rogers, Lynn M.

    1983-12-20

    In a fluidized bed apparatus a method for controlling the height of the fdized bed, taking into account variations in the density of the bed. The method comprises taking simultaneous differential pressure measurements at different vertical elevations within the vessel, averaging the differential pressures, determining an average fluidized bed density, then periodically calculating a weighting factor. The weighting factor is used in the determination of the actual bed height which is used in controlling the fluidizing means.

  2. Assessing the repeatability of terrestrial laser scanning for monitoring gully topography: A case study from Aratula, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Goodwin, Nicholas Robert; Armston, John; Stiller, Isaac; Muir, Jasmine

    2016-06-01

    Terrestrial laser scanning (TLS) technology is a powerful tool for quantifying gully morphology and monitoring change over time. This is due to the high sampling density, sub-centimetre positional accuracies (x, y, z), flexibility of survey configurations and ability to link multiple TLS scans together. However, to ensure correct interpretation of results, research is needed to test the repeatability of TLS derived products to quantify the accuracy and separate 'false' from 'true' geomorphic change. In this study, we use the RIEGL VZ400 scanner to test the repeatability of TLS datasets for mapping gully morphology. We then quantify change following a rainfall event of approximately 100 mm. Our study site, located in south-east Queensland, Australia was chosen to be challenging from a repeatability perspective with high topographic variability. The TLS data capture involved three sets of linked scans: one survey pre-rainfall, to be compared to two surveys post-rainfall acquired on consecutive days. Change is considered negligible in the two post-rainfall scans to test survey repeatability. To verify TLS accuracy, an independent dataset of gully extent and spot heights were acquired using traditional total station techniques. Results confirm that the TLS datasets can be registered multi-temporally at sub-centimetre levels of accuracy in three dimensions. Total station and TLS elevation samples showed strong agreement with a mean error and standard deviation (SD) of residuals equal to 0.052 and 0.047 m, respectively (n = 889). Significantly, our repeatability tests found that return type and pulse deviation influence the accuracy and repeatability of DEMs in gully environments. Analysis of consecutive day datasets showed that DEMs derived from first return data recorded 40% higher SD of residual error than DEMs using multiple return data. A significant empirical relationship between pulse deviation and the variance of residuals for repeat DEMs is also shown (r2 = 0

  3. SF3M software: 3-D photo-reconstruction for non-expert users and its application to a gully network

    NASA Astrophysics Data System (ADS)

    Castillo, C.; James, M. R.; Redel-Macías, M. D.; Pérez, R.; Gómez, J. A.

    2015-08-01

    Three-dimensional photo-reconstruction (PR) techniques have been successfully used to produce high-resolution surface models for different applications and over different spatial scales. However, innovative approaches are required to overcome some limitations that this technique may present for field image acquisition in challenging scene geometries. Here, we evaluate SF3M, a new graphical user interface for implementing a complete PR workflow based on freely available software (including external calls to VisualSFM and CloudCompare), in combination with a low-cost survey design for the reconstruction of a several-hundred-metres-long gully network. SF3M provided a semi-automated workflow for 3-D reconstruction requiring ~ 49 h (of which only 17 % required operator assistance) for obtaining a final gully network model of > 17 million points over a gully plan area of 4230 m2. We show that a walking itinerary along the gully perimeter using two lightweight automatic cameras (1 s time-lapse mode) and a 6 m long pole is an efficient method for 3-D monitoring of gullies, at a low cost (~ EUR 1000 budget for the field equipment) and the time requirements (~ 90 min for image collection). A mean error of 6.9 cm at the ground control points was found, mainly due to model deformations derived from the linear geometry of the gully and residual errors in camera calibration. The straightforward image collection and processing approach can be of great benefit for non-expert users working on gully erosion assessment.

  4. Ash bed level control system for a fixed-bed coal gasifier

    DOEpatents

    Fasching, George E.; Rotunda, John R.

    1984-01-01

    An ash level control system is provided which incorporates an ash level meter to automatically control the ash bed level of a coal gasifier at a selected level. The ash level signal from the ash level meter is updated during each cycle that a bed stirrer travels up and down through the extent of the ash bed level. The ash level signal is derived from temperature measurements made by thermocouples carried by the stirrer as it passes through the ash bed and into the fire zone immediately above the ash bed. The level signal is compared with selected threshold level signal to determine if the ash level is above or below the selected level once each stirrer cycle. A first counter is either incremented or decremented accordingly. The registered count of the first counter is preset in a down counter once each cycle and the preset count is counted down at a selected clock rate. A grate drive is activated to rotate a grate assembly supporting the ash bed for a period equal to the count down period to maintain the selected ash bed level. In order to avoid grate binding, the controller provides a short base operating duration time each stirrer cycle. If the ash bed level drops below a selected low level or exceeds a selected high level, means are provided to notify the operator.

  5. Partial cranium of Cercopithecoides kimeui Leakey, 1982 from Rawi Gully, southwestern Kenya.

    PubMed

    Frost, Stephen R; Plummer, Thomas; Bishop, Laura C; Ditchfield, Peter; Ferraro, Joseph; Hicks, Jason

    2003-11-01

    The Rawi Gully, located on the Homa Peninsula in southwestern Kenya, has produced several fossil elements of a large cercopithecid from sediments approximately 2.5 million years old (Ma). Nearly all of these elements appear to represent a single adult male individual of the colobine species Cercopithecoides kimeui Leakey, 1982. Part of the face, mandible, dentition, and several small postcranial fragments were collected by the Homa Peninsula Paleoanthropological Project (HPPP) in 1994 and 1995. This individual also appears to be represented by material collected in two previous expeditions to the site, one led by David Pilbeam in the 1970s and an earlier expedition led by L.S.B. Leakey in 1933. This specimen may extend the first appearance of C. kimeui by approximately 500 Kyr, and provides the first evidence for much of the male facial morphology in this species. Furthermore, Rawi may represent a more wooded habitat than the other occurrences of C. kimeui at Olduvai Gorge, Tanzania, and Koobi Fora, Kenya, indicating that C. kimeui may have been relatively flexible in its habitat preferences.

  6. The summer assemblage of large pelagic Crustacea in the Gully submarine canyon: Major patterns

    NASA Astrophysics Data System (ADS)

    MacIsaac, K. G.; Kenchington, T. J.; Kenchington, E. L. R.; Best, M.

    2014-06-01

    We describe the trawl-vulnerable crustacean micronekton and macrozooplankton of the Gully, a large, shelf-incising submarine canyon off Nova Scotia, Canada, and a Marine Protected Area. Over 68 species of pelagic crustacea were collected with an International Young Gadoid Pelagic Trawl during three annual summer surveys at one fixed station in the canyon. Depths sampled ranged from the surface to the upper bathypelagic zone, concentrated in the upper 1250 m, with a maximum depth of 1500 m. The crustacean fauna was dominated by cold temperate species typical of mid- to higher-latitudes in the North Atlantic. Meganyctiphanes norvegica and Eusergestes arcticus were particularly dominant in terms of both observed biomass and abundance above 750 m depth. At least 17 species were new records for Canadian waters. The species assemblage of the station varied primarily with depth and diel cycle, the only dominant members of the assemblage showing pronounced inter-annual variations in catch being M. norvegica and Themisto gaudichaudii, both relatively shallow living species.

  7. Temporal Dynamics of Gully Evolution in a Small, Ephemeral Channel in a Semiarid Watershed

    NASA Astrophysics Data System (ADS)

    Nichols, Mary; Nearing, Mark

    2015-04-01

    Incised channels that terminate at a vertical-wall gully heads are common features in semiarid watersheds. The geomorphic evolution of such channels is often dominated by migration of the headwall. The evolution of a headwall in a low order channel on the USDA-ARS Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona has been monitored since 2004, and since 2012, time-lapse photography has been employed to observe the temporal dynamics at high resolution. A Canon A1300 off the shelf point and shoot digital camera mounted inside a weatherproof Pelican case has been taking 15 mp photographs since 2012. The camera power supply was modified to run from a 12V car battery that was charged with a 25 Watt solar panel through a solar controller. During the runoff season from July through September, images were collected every 30 seconds and the time step was increase to 30 minutes during winter months. The field of view covers the headcut and the immediate surroundings. Runoff events were distinct flash floods in response to high intensity rain. The temporal sequencing of the dominant processes of erosion including mass wasting, plunge pool erosion, and piping are described. In addition, we present a description of the time-lapse camera system with suggestions for future improvements.

  8. [Niche characteristics of dominant populations of Sophora davidii community in loess gully region].

    PubMed

    Li, Dengwu; Zhang, Wenhui; Ren, Zhengzheng

    2005-12-01

    Based on field investigation data and employing Levin and niche proportional similarity formulae, this paper calculated the niche breadth, niche proportional similarity, and niche overlap of 13 dominant species of Sophora davidii community in loess gully region. The results showed that the niche breadth of the dominant populations of Sophora davidii community decreased in order of Sophora davidii (0.964), Artemisia giraldii (0.775), Arteniisia gmelinii (0.664), Thenmeda triandra var. japonica (0.508), Polygala tenuifolia (0.485), Setaria viridis (0.399), Cynodon dactylon (0.393), Bothriochloa ischaemum (0.327), Lespedeza davurica (0.321), Stipa bungeana (0.472), Periploca sepium (0.292), Clemnatis fruticosa (0.251), and Cleistogenes squarrosa (0.234). The niche proportional similarity between Sophora davidii and other species was 0.21-0.76, while the niche overlap was not high, which meant that there was no severe competition between them. It could be concluded that Sophora davidii was the dominant population in the community, with most resources utilization and most adaptability to the ecosystem. PMID:16515163

  9. [Comparison of ecophysiological characteristics of seven plant species in semiarid loess hilly-gully region].

    PubMed

    Xu, Bing-cheng; Shan, Lun; Li, Feng-min

    2007-05-01

    The diurnal course of photosynthetic rate, transpiration rate, and leaf water potential (psi L) of five plant species in North Shaanxi loess hilly-gully region were measured in dry seasons. Based on the daily maximum photosynthetic and transpiration rates, daily total assimilation and transpiration, and diurnal change characteristics of psi L, the test plants were classified into different eco-adaptation types. Panicum virgatum L. had high photosynthetic rate, low transpiration rate and high water use efficiency (WUE), and its drought adaptation strategy was to delay dehydration by developing high psi L. Medicago sativa had high photosynthetic and transpiration rates but low WUE, while Lespedeza dahurica had low photosynthetic and transpiration rates and low WUE. Their drought adaptation strategies were the same, namely, by increasing psi L delay dehydration. Bothriochloa ischaemum had high photosynthetic rate, relative high transpiration rate and medium WUE, and its drought-resistant strategy was to decrease psi L to endure dehydration. Astragalus adsurgens had similar characteristics in diurnal courses of photosynthesis with B. ischaemum, and its drought adaption strategy was to delay dehydration by developing low psi psi L.

  10. [Characteristics of seed rain on abandoned slopes in the hilly-gullied Loess Plateau, Northwest China].

    PubMed

    Yu, Wei-jie; Chen, Yu; Jiao, Ju-ying; Wang, Dong-li; Wang, Zhi-jie; Wei, Yan-hong; Kou, Meng; Yin, Qiu-long

    2015-02-01

    The objective of this study was to analyze the dynamic characteristics of seed rain on abandoned slopes in the hilly-gullied Loess Plateau region and identify the relationship between seed rain and standing vegetation. Three abandoned slopes were chosen as sampling sites in Zhifanggou watershed. Thirty traps were installed at each site to collect seed rain from October 2010 to April 2013. Standing vegetation was surveyed to identify dominant species in August 2011 and 2012, respectively. Thirty-seven species belonging to seventeen families were identified in the seed rain, and the dominant species, i.e., Lespedeza davurica, Astragalus scaberrimus, Setaria viridis, Cleistogenes squarrosa, Stipa bungeana, Bothriochloa ischcemum, Artemisia scoparia, A. gmelinii, and Heteropappus altaicus, took up to 95.8% of the total seed rain. Three species in seed rain were not found in the standing vegetation. The Sorensen similarity index between seed rain and standing vegetation was 0.77. Seed rain densities were 3737 and 6449 seeds · m(-2) in May 2011-April 2012 and May 2012-April 2013, respectively, and alternate bearing existed. During the study period, seed rain from different positions varied from 3853 to 37923 seeds · m(-2) and belonged to 7-15 species. The results indicated the space limitation of seed dispersal. Seed rain densities were in the middle of the pack compared with similar ecosystems in other studies. High temporal and spatial heterogeneity of seed rain was observed because of rainfall, microtopography and so on.

  11. [Characteristics of seed rain on abandoned slopes in the hilly-gullied Loess Plateau, Northwest China].

    PubMed

    Yu, Wei-jie; Chen, Yu; Jiao, Ju-ying; Wang, Dong-li; Wang, Zhi-jie; Wei, Yan-hong; Kou, Meng; Yin, Qiu-long

    2015-02-01

    The objective of this study was to analyze the dynamic characteristics of seed rain on abandoned slopes in the hilly-gullied Loess Plateau region and identify the relationship between seed rain and standing vegetation. Three abandoned slopes were chosen as sampling sites in Zhifanggou watershed. Thirty traps were installed at each site to collect seed rain from October 2010 to April 2013. Standing vegetation was surveyed to identify dominant species in August 2011 and 2012, respectively. Thirty-seven species belonging to seventeen families were identified in the seed rain, and the dominant species, i.e., Lespedeza davurica, Astragalus scaberrimus, Setaria viridis, Cleistogenes squarrosa, Stipa bungeana, Bothriochloa ischcemum, Artemisia scoparia, A. gmelinii, and Heteropappus altaicus, took up to 95.8% of the total seed rain. Three species in seed rain were not found in the standing vegetation. The Sorensen similarity index between seed rain and standing vegetation was 0.77. Seed rain densities were 3737 and 6449 seeds · m(-2) in May 2011-April 2012 and May 2012-April 2013, respectively, and alternate bearing existed. During the study period, seed rain from different positions varied from 3853 to 37923 seeds · m(-2) and belonged to 7-15 species. The results indicated the space limitation of seed dispersal. Seed rain densities were in the middle of the pack compared with similar ecosystems in other studies. High temporal and spatial heterogeneity of seed rain was observed because of rainfall, microtopography and so on. PMID:26094452

  12. [Landscape spatial pattern of typical loess hilly-gully watershed based on ALOS imagery].

    PubMed

    Mai, Kai-le; Zhang, Wen-hui

    2011-03-01

    Based on the ALOS satellite medium and high resolution images, seven landscape types closely related to the ecosystem restoration, farming, and living of Yan' gou watershed, a typical watershed in loess hilly-gully region, were interpreted. The landscape pattern and function of the watershed in 2007 were analyzed with the landscape indices of diversity and heterogeneity, and the landscape distribution suitability of the whole and parts of the watershed were evaluated, combined with the digital elevation model (DEM) data. The results showed that the dominant landscape types in the watershed were bush and forest, which were mainly distributed on the slopes with a gradient greater than 25 degrees. The patch fractal dimension of the watershed was 1.09, suggesting that the general landscape spatial pattern was stable. The area ratio of the three landscape functional types of eco-protection, product economy, and living service was 23:9:1. The suitability of the whole watershed landscape distribution was 0.76, suggesting that the overall landscape distribution was relatively reasonable. However, the land-use suitability of semi-shade slopes and of the areas with an altitude less than 900 m was lower, being 0.74 and 0.02, respectively.

  13. Cooling of debris beds

    SciTech Connect

    Barleon, L.; Thomauske, K.; Werie, H.

    1984-04-01

    The dependence of the dryout heat flux for volume-heated particulate beds on bed height (less than or equal to40 cm), particle diameter (0.06 to 16 mm), stratification and boundary conditions (saturated and subcooled liquid, adiabatic and cooled bottom and sidewalls) has been determined for water and Freon-113. Channel penetration through subcooled layers and ''downward boiling'' due to capillarity effects have been observed. Different types of bed disturbances have been identified, and their effect on dryout has been studied. Using existing theoretical models, which have been verified by the experiments, the upper limit of the thermal load on support structures has been calculated as a function of the particle size and bottom temperature for reactor accident conditions (Pu/U-oxide particles in sodium).

  14. Use of the 3-D scanner in mapping and monitoring the dynamic degradation of soils: case study of the Cucuteni-Baiceni Gully on the Moldavian Plateau (Romania)

    NASA Astrophysics Data System (ADS)

    Romanescu, G.; Cotiuga, V.; Asandulesei, A.; Stoleriu, C.

    2012-03-01

    The 3-D scanner, a rapid and precise means of monitoring the dynamics of erosive processes, was first used nationally (Romania) as a new technique of cartography and monitoring the dynamics of soil degradation processes in the Moldavian Plateau. Three sets of measurements took place: in 2008, in 2009 and in 2010, at intervals of exactly one year for the first and six months for the second part. Qualitative and quantitative differences were highlighted. The data obtained were corroborated with precipitation in the area studied. The 3-D scanner has a measurement accuracy of 6 mm. The map highlights the dynamics of gullies developed and may form the basis for the prediction of soil degradation phenomena. The dynamics of the gully and the type of land use show that the phenomenon of erosion of the Moldova Plateau will continue to accelerate. In this case, the gully attacked and destroyed an archaeological site of national importance. The rate of advance of the Cucuteni-Baiceni gully is extremely high (10 m/1.6 years). There are no measures at all to reduce or fight the process of the gully advance. Maximum erosion occurred at the beginning of spring after a winter rich in rainfall, which made the terrain subject to the process of subsidence.

  15. Use of the 3-D scanner in mapping and monitoring the dynamic degradation of soils. Case study of the Cucuteni-Baiceni Gully on the Moldavian Plateau (Romania).

    NASA Astrophysics Data System (ADS)

    Romanescu, G.; Venedict, B.; Cotiuga, V.; Asandulesei, A.

    2011-07-01

    The 3-D Scanner, a rapid and precise means of monitoring the dynamics of erosive processes, was used, first of all nationally (Romania), as a new technique of cartography and monitoring the dynamics of soil degradation processes in the Moldavian Plateau. Three sets of measurements took place: in 2008, in 2009 and in 2010, at intervals of exactly one year for the first and six months for the second part. Qualitative and quantitative differences were highlighted. The data obtained were corroborated with precipitation in the area studied. The 3-D scanner has a measurement accuracy of 6 mm. The map highlights the dynamics of gullies developed and may form the basis for the prediction of soil degradation phenomena. The dynamics of the gully and the type of land use show that the phenomenon of erosion of the Moldova Plateau will continue to accelerate. In this case the gully attacked and destroyed an archaeological site of national importance. The rate of advance of the Cucuteni-Baiceni gully is extremely high (10 m/1.6 yr). There are no measures at all to reduce or fight the process of the gully advance. Maximum erosion occurred at the beginning of spring after a winter rich in rainfall, which made the terrain subject to the process of subsidence.

  16. Effects of watershed management practices on the relationships among rainfall, runoff, and sediment delivery in the hilly-gully region of the Loess Plateau in China

    NASA Astrophysics Data System (ADS)

    Yan, Qinghong; Lei, Tingwu; Yuan, Cuiping; Lei, Qixiang; Yang, Xiusheng; Zhang, Manliang; Su, Guangxu; An, Leping

    2015-01-01

    The relationships among rainfall, runoff, and sediment delivery are significant in predicting soil erosion and in evaluating the benefits of watershed management practices (WMP) on the hilly-gully regions of the Loess Plateau. Hydrologic data (1987 to 2010) were analyzed for variations in precipitation, runoff, and sediment delivery at annual and event scale. These data were obtained from the Qiaozi East watershed (QE) and the Qiaozi West watershed (QW) with and without WMP, respectively. Results indicated that the runoff coefficients of the watersheds decreased significantly, although the runoff coefficient of QE was less than half of that of QW. Sediment delivery decreased more in QE than in QW mainly because of the increase in vegetation cover in both watersheds. In QE, the relationship between runoff and sediment delivery did not change significantly from 1987 to 2006, although the variation was significant from 2007 to 2010. In QW, the relationship between runoff and sediment delivery was not notably altered from 1987 to 2010. This finding suggested that vegetation practices and engineering measures on the hillslope did not strongly affect the relationship between runoff and sediment delivery in the watersheds. But the construction of check dams reduced gully erosion and the suspended sediment concentration. Hence, control practices for gully erosion significantly influenced the relationship between runoff and sediment delivery. This study suggests that a combination of hillslope and gully erosion control practices effectively reduces erosion and sediment delivery in the hilly-gully regions of the Loess Plateau.

  17. Fluidized bed coal desulfurization

    NASA Technical Reports Server (NTRS)

    Ravindram, M.

    1983-01-01

    Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

  18. Staged fluidized bed

    DOEpatents

    Mallon, R.G.

    1983-05-13

    The invention relates to oil shale retorting and more particularly to staged fluidized bed oil shale retorting. Method and apparatus are disclosed for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

  19. Effects of current exposure on habitat preference of mobile 0-group epibenthos for intertidal seagrass beds ( Zostera noltii) in the northern Wadden Sea

    NASA Astrophysics Data System (ADS)

    Polte, Patrick; Schanz, Anja; Asmus, Harald

    2005-03-01

    In the northern Wadden Sea, the extent of intertidal seagrass beds, their plant biomass and shoot density highly depends on local current regimes. This study deals with the role of intertidal Zostera noltii beds as nursery for mobile epibenthic macrofauna and the impact of seagrass bed characteristics on their abundance and distribution patterns. According to their exposure to the main tidal gullies, sampling sites were separated into exposed, semi-exposed and sheltered. Dominant species of crustaceans and demersal fish were studied in respect of their abundances within seagrass beds and adjacent unvegetated areas. Quantitative sampling was performed at day and night high tide using a portable drop trap. In general, species composition varied little between seagrass beds and bare sand. However, the presence of vegetation had a quantitative effect increasing individual numbers of common epifaunal species. Abundances of 0-group shore crabs ( Carcinus maenas), common gobies ( Pomatoschistus microps) and brown shrimps ( Crangon crangon) were highest within sheltered seagrass beds. With decreasing plant density habitat preference of epibenthos changed on species level. By regulating the habitat complexity the currents regime is profoundly influencing the nursery function of intertidal seagrass beds in the Wadden Sea.

  20. Acoustic bed velocity and bed load dynamics in a large sand bed river

    USGS Publications Warehouse

    Gaeuman, D.; Jacobson, R.B.

    2006-01-01

    Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate to conditions near the stream bed is necessary to make the method practical for quantitative applications. In this paper, we discuss the response of ADCP bed velocity measurements, defined as the near-bed sediment velocity detected by the instrument's bottom-tracking feature, to changing sediment-transporting conditions in the lower Missouri River. Bed velocity represents a weighted average of backscatter from moving bed load particles and spectral reflections from the immobile bed. The ratio of bed velocity to mean bed load particle velocity depends on the concentration of the particles moving in the bed load layer, the bed load layer thickness, and the backscatter strength from a unit area of moving particles relative to the echo strength from a unit area of unobstructed bed. A model based on existing bed load transport theory predicted measured bed velocities from hydraulic and grain size measurements with reasonable success. Bed velocities become more variable and increase more rapidly with shear stress when the transport stage, defined as the ratio of skin friction to the critical shear stress for particle entrainment, exceeds a threshold of about 17. This transition in bed velocity response appears to be associated with the appearance of longer, flatter bed forms at high transport stages.

  1. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  2. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1987-05-12

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  3. Fluid bed material transfer method

    DOEpatents

    Pinske, Jr., Edward E.

    1994-01-01

    A fluidized bed apparatus comprising a pair of separated fluid bed enclosures, each enclosing a fluid bed carried on an air distributor plate supplied with fluidizing air from below the plate. At least one equalizing duct extending through sidewalls of both fluid bed enclosures and flexibly engaged therewith to communicate the fluid beds with each other. The equalizing duct being surrounded by insulation which is in turn encased by an outer duct having expansion means and being fixed between the sidewalls of the fluid bed enclosures.

  4. Technology test bed review

    NASA Astrophysics Data System (ADS)

    McConnaughey, H. V.

    1992-07-01

    The topics are presented in viewgraph form and include the following: (1) Space Shuttle Main Engine (SSME) technology test bed (TTB) history; (2) TTB objectives; (3) TTB major accomplishments; (4) TTB contributions to SSME; (5) major impacts of 3001 testing; (6) some challenges to computational fluid dynamics (CFD); (7) the high pressure fuel turbopump (HPFTP); and (8) 3001 lessons learned in design and operations.

  5. Technology test bed review

    NASA Technical Reports Server (NTRS)

    Mcconnaughey, H. V.

    1992-01-01

    The topics are presented in viewgraph form and include the following: (1) Space Shuttle Main Engine (SSME) technology test bed (TTB) history; (2) TTB objectives; (3) TTB major accomplishments; (4) TTB contributions to SSME; (5) major impacts of 3001 testing; (6) some challenges to computational fluid dynamics (CFD); (7) the high pressure fuel turbopump (HPFTP); and (8) 3001 lessons learned in design and operations.

  6. Bed rest during pregnancy

    MedlinePlus

    ... for support groups, bulletin boards, and chat rooms online for moms-to-be who are also on bed rest. Expect emotional ups and downs. Share your hopes and worries with your partner. Let each other vent if needed. If sex is not allowed, look for other ways to ...

  7. Hidden gully erosion - detection and characterization of piping systems using geomorphological and geophysical methods (GPR, ERT)

    NASA Astrophysics Data System (ADS)

    Bernatek-Jakiel, Anita; Kondracka, Marta

    2016-04-01

    The significance of piping in gully formation and hillslope hydrology has been discussed for many years. However, piping as a subsurface erosion caused by water flowing through the soil is still considered as one of the most difficult erosion processes to study, because it occurs below the soil surface and traces of piping become visible on the surface only when a pipe roof collapses, or a pipe inlet or a pipe outlet has been located. Detection of pipes and their complex characterization is still a methodological challenge. Therefore, this study aims at a better detection and characterization of piping systems in a mountainous area under a temperate climate using geomorphological mapping and geophysical methods (ground penetrating radar and electrical resistivity tomography). The survey was carried out in the Bereźnica Wyżna catchment, in the Bieszczady Mts. (Eastern Carpathians, Poland), where pipes develop in Cambisols at a depth ranging from ca 0.70 to 1.00 m. The geomorphological mapping was carried out in the in the whole catchment (2.96 km2), whereas the geophysical survey was limited to two zones (zone A - ca 32 x 82 m, zone B - ca 58 x 115 m). In this study a standard RAMAC GPR system (Malå GeoScience) with shielded 500 MHz antenna was used. The electrical resistivity tomography (ERT) was performed using electrical imaging system LUND with Terrameter SAS 4000 produced by company ABEM. The ERT and GPR data were interpreted in the RES2DINV (Geotomo Software) and RadExplorer software (DECO Geophysical Ltd) respectively. In total, 3 longitudinal and 26 transverse GPR profiles and five ERTs were performed. The used geophysical techniques are shown to be successful in identifying pipes tested in the pilot catchment. Pipes identified by GPR and ERT were verified by the surface indicators (i.e. lowering of surface above pipes). The GPR and ERT applications suggest that piping systems density is much greater than could be detected from surface observation alone

  8. Pyrophoricity of tritium-storage bed materials

    SciTech Connect

    Longhurst, G.R.

    1988-09-01

    Experiments were conducted on samples of depleted uranium and on intermetallic compounds of zirconium-cobalt and lanthanum-nickel-aluminide to evaluate the pyrophoricity of the activated materials and their hydrides and deuterides on exposure to air. None of the materials spontaneously ignited when exposed to room temperature air, but the uranium and the zirconium-cobalt both ignited in air at moderately elevated temperatures. Activated dehyrdided materials ignited at essentially the same temperatures. Deuterides showed effectively the same characteristics as the hydrides except the ignition temperature of zirconium-cobalt deuteride was reduced by 20 - 50 K from that of the hydride. The pyrophoricity of these materials raises concern about the possibility of fires in tritium-storage beds with attendant damage to the bed and dispersal of tritiated debris, but fires may not occur until the bed is heated.

  9. Spatial structures of stream and hillslope drainage networks following gully erosion after wildfire

    USGS Publications Warehouse

    Moody, J.A.; Kinner, D.A.

    2006-01-01

    The drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1-1000 m2) representative of hillslopes, and the small scale (1000 m2 to 1 km2), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1-1000 km2), representative of perennial stream networks, was derived from a 30-m digital elevation model and analysed by computer analysis. Scaling laws used to describe large-scale drainage networks could be extrapolated to the small scale but could not describe the smallest scale of drainage structures observed in the hillslope region. The hillslope drainage network appears to have a second-order effect that reduces the number of order 1 and order 2 streams predicted by the large-scale channel structure. This network comprises two spatial patterns of rills with width-to-depth ratios typically less than 10. One pattern is parallel rills draining nearly planar hillslope surfaces, and the other pattern is three to six converging rills draining the critical source area uphill from an order 1 channel head. The magnitude of this critical area depends on infiltration, hillslope roughness and critical shear stress for erosion of sediment, all of which can be substantially altered by wildfire. Order 1 and 2 streams were found to constitute the interface region, which is altered by a disturbance, like wildfire, from subtle unchannelized drainages in unburned catchments to incised drainages. These drainages are characterized by gullies also with width-to-depth ratios typically less than 10 in burned catchments. The regions (hillslope, interface and chanel) had different drainage network structures to collect and transfer water and sediment. Copyright ?? 2005 John Wiley & Sons, Ltd.

  10. Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This mosaic of two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows about 20 different gullies coming down the south-facing wall of a trough in the Sirenum Fossae/Gorgonum Chaos region of the martian southern hemisphere. Each channel and its associated fan--or apron--of debris appears to have started just below the same hard, resistant layer of bedrock located approximately 100 meters (about 325 feet) below the top of the trough wall. The layer beneath this hard, resistant bedrock is interpreted to be permeable, which allows ground water to percolate through it and--at the location of this trough--seep out onto the martian surface. The channels and aprons only occur on the south-facing slope of this valley created by faults on each side of the trough. The depression is approximately 1.4 km (0.9 mi) across.

    The mosaic was constructed from two pictures taken on September 16, 1999, and May 1, 2000. The black line is a gap between the two images that was not covered by MOC. The scene covers an area approximately 5.5 kilometers (3.4 miles) wide by 4.9 km (3.0 mi) high. Sunlight illuminates the area from the upper left. The image is located near 38.5oS, 171.3oW. MOC high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.

  11. Detecting major environmental parameters influencing the gully erosion occurrence in Mediterranean karst landscapes of Lebanon using remote sensing and GIS statistical correlations

    NASA Astrophysics Data System (ADS)

    Kheir, Rania Bou; Hansmann, Berthold; Abdallah, Chadi

    2010-05-01

    Soil erosion by water is one of the major causes of land degradation in Mediterranean karst environments, including Lebanon, which represents a good case study. This research deals with how to use Geographic Information Systems (GIS) for establishing the relationships between gully erosion occurrence and different environmental parameters over a representative region of Lebanon. Factors influencing the gully erosion process can be represented by different parameters, and each can be extracted from remote sensing, digital elevation models DEMs, ancillary maps or field observations. These parameters can be endogenous/quasi-static, i.e. soil type, organic matter content, soil depth, lithology, proximity to fault zone, karstification, distance to drainage line, slope gradient, slope aspect, slope curvature, or exogenous/dynamic triggering the erosion process, i.e. land cover/use, proximity to sources and rainfall erosivity. All these parameters have been analyzed and correlated with existing gullies under a GIS environment. The gullies were first detected through visual interpretation of two stereo-pairs of SPOT 4 images (anaglyph) at 10 m resolution. This study indicates, depending on bivariate remote sensing and GIS statistical correlations (Kendall Tau-b correlation), that the soil type is the most influencing factor on gully erosion occurrence. It also shows that statistical correlations to gullies exist best between the extracted parameters at the following decreasing order of importance: soil type-lithology, soil-land cover/use, soil-slope gradient, lithology-distance to drainage line, and soil type-karstification at 1% level of significance, and lithology-proximity to fault line, slope aspect-land cover/use, and soil type-slope curvature at 5% level of significance. These correlations were verified and checked through field observations and explained using univariate statistical correlations. Therefore, they could be extrapolated to other Mediterranean karst

  12. Evidence for Recent Liquid Water on Mars: Gullies at 70oS in Polar Pit Walls

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site]

    Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold--well below freezing--all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30o and 70o.

    The highest latitude at which martian gullies have been found is around 70o-75oS on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130oC or -200oF). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls (above, left).

    Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement--dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed.

    Centered near 70.7oS, 355.7oW, the MOC image was acquired July 14, 1999, and covers an area approximately 2.8 km (1.7 mi) wide by 2.1 km (1.3 mi) high. Sunlight illuminates the MOC image from the upper left and north is toward the upper left. The context view (right) is from the Viking 2 orbiter and was acquired in 1977. The Viking picture is illuminated from the top/upper left; north is toward the upper right. The

  13. Erosion of heat exchanger tubes in fluidized beds

    SciTech Connect

    Johnson, E.K.; Flemmer, R.L.C.

    1991-01-01

    This final report describes the activities of the 3-year project entitled Erosion of Heat Exchanger Tubes In Fluidized Beds.'' which was completed at the end of 1990. Project accomplishments include the collection of a substantial body of wear data In a 24in. [times] 24in. fluidized bed, comparative wear results In a 6in. [times] 6in. fluidized bed, the development of a dragometer and the collection of a comprehensive set of drag force data in the 24in. [times] 24in. bed, Fast Fourier Transform (FFT) analysis of bubble probe data to establish dominant bubble frequencies in the 24in. [times] 24in. bed, the use of a heat flux gauge for measurement of heat transfer coefficients in the 24in. [times] 24in. bed and the modeling of the tube wear in the 24in. [times] 24in. bed. Analysis of the wear data from the 24in. square bed indicates that tube wear increases with increase in superficial velocity, and with increase in tube height. The latter effect is a result of the tubes higher up in the bed seeing greater movement of dense phase than tubes lower down In the bed. In addition, tube wear was found to decrease with increase in particle size, for constant superficial velocity. Three models of tube wear were formulated and provided acceptable prediction of wear when compared with the experimental data.

  14. Bacterial counts associated with sawdust and recycled manure bedding treated with commercial conditioners.

    PubMed

    Hogan, J S; Bogacz, V L; Thompson, L M; Romig, S; Schoenberger, P S; Weiss, W P; Smith, K L

    1999-08-01

    Bacteria counts associated with untreated organic bedding materials were compared with those of bedding treated with either an alkaline commercial bedding conditioner, acidic commercial bedding conditioner, or hydrated lime. Bedding materials were recycled manure and kiln-dried sawdust. The effects of bedding treatments on bacteria counts differed between bedding types. Each of the bedding treatments significantly reduced bacteria in recycled manure prior to use. The alkaline conditioner and hydrated lime effectively inhibited bacteria in recycled manure for 1 d. Bedding counts and teat swabs of cows housed on recycled manure treated with the alkaline conditioner were reduced on d 2. The use of the acid conditioner in recycled manure had little effect on bacteria in bedding. Sawdust differed from recycled manure in that bacteria in untreated sawdust prior to use were minimal, and populations increased rapidly during the first 2 d after use as bedding. The acid conditioner had a bacteriostatic effect in sawdust, evident by the reduction of bacteria on d 2. The alkaline conditioner and hydrated lime did not alter bacteria counts in sawdust compared with untreated sawdust. Antibacterial activity of each conditioner deteriorated between d 2 and d 6 in both beddings. The antibacterial activities of conditioners were related to the pH of bedding materials. The use of commercial bedding conditioners initially reduced bacterial counts; however, the antibacterial effects had diminished between d 2 and 6 after use in bedding. PMID:10480094

  15. Respiration and body movement analysis during sleep in bed using hetero-core fiber optic pressure sensors without constraint to human activity

    NASA Astrophysics Data System (ADS)

    Nishyama, Michiko; Miyamoto, Mitsuo; Watanabe, Kazuhiro

    2011-01-01

    We describe respiration monitoring in sleep using hetero-core fiber optic pressure sensors. The proposed hetero-core fiber optic sensor is highly sensitive to macrobending as a result of the core diameter difference due to stable single-mode transmission. Pressure sensors based on hetero-core fiber optics were fabricated to have a high sensitivity to small pressure changes resulting from minute body motions, such as respiration, during sleep and large pressure changes, such as those caused by a rollover. The sensors are installed in a conventional bed. The pressure characteristic performance of all the fabricated hetero-core fiber optic pressure sensors is found to show a monotonic response with weight changes. A respiration monitoring test in seven subjects efficiently demonstrates the effective use of eight hetero-core pressure sensors installed in a bed. Additionally, even in the case of different body postures, such as lying on one's side, a slight body movement due to respiration is detected by the hetero-core pressure sensors.

  16. The role of biophysical cohesion on subaqueous bed form size

    NASA Astrophysics Data System (ADS)

    Parsons, Daniel R.; Schindler, Robert J.; Hope, Julie A.; Malarkey, Jonathan; Baas, Jaco H.; Peakall, Jeffrey; Manning, Andrew J.; Ye, Leiping; Simmons, Steve; Paterson, David M.; Aspden, Rebecca J.; Bass, Sarah J.; Davies, Alan G.; Lichtman, Ian D.; Thorne, Peter D.

    2016-02-01

    Biologically active, fine-grained sediment forms abundant sedimentary deposits on Earth's surface, and mixed mud-sand dominates many coasts, deltas, and estuaries. Our predictions of sediment transport and bed roughness in these environments presently rely on empirically based bed form predictors that are based exclusively on biologically inactive cohesionless silt, sand, and gravel. This approach underpins many paleoenvironmental reconstructions of sedimentary successions, which rely on analysis of cross-stratification and bounding surfaces produced by migrating bed forms. Here we present controlled laboratory experiments that identify and quantify the influence of physical and biological cohesion on equilibrium bed form morphology. The results show the profound influence of biological cohesion on bed form size and identify how cohesive bonding mechanisms in different sediment mixtures govern the relationships. The findings highlight that existing bed form predictors require reformulation for combined biophysical cohesive effects in order to improve morphodynamic model predictions and to enhance the interpretations of these environments in the geological record.

  17. Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank Farm Blend) By Fluidized Bed Steam Reformation (FBSR)

    SciTech Connect

    Jantzen, C. M.; Crawford, C. L.; Bannochie, C. J.; Burket, P. R.; Cozzi, A. D.; Daniel, W. E.; Hall, H. K.; Miller, D. H.; Missimer, D. M.; Nash, C. A.; Williams, M. F.

    2013-08-01

    The U.S. Department of Energy’s Office of River Protection (ORP) is responsible for the retrieval, treatment, immobilization, and disposal of Hanford’s tank waste. A key aspect of the River Protection Project (RPP) cleanup mission is to construct and operate the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the RPP mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order, also known as the Tri-Party Agreement (TPA), i.e. December 31, 2047. Supplemental Treatment is likely to be required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. The Supplemental Treatment chosen will immobilize that portion of the retrieved LAW that is not sent to the WTP’s LAW Vitrification facility into a solidified waste form. The solidified waste will then be disposed on the Hanford site in the Integrated Disposal Facility (IDF). Fluidized Bed Steam Reforming (FBSR) offers a moderate temperature (700-750°C) continuous method by which LAW can be processed irrespective of whether the waste contain organics, nitrates, sulfates/sulfides, chlorides, fluorides, volatile radionuclides or other aqueous components. The FBSR technology can process these wastes into a crystalline ceramic (mineral) waste form. The mineral waste form that is produced by co-processing waste with kaolin clay in an FBSR process has been shown to be comparable to LAW glass, i.e. leaches Tc-99, Re and Na at <2g/m2 during ASTM C1285 (Product Consistency) durability testing. Monolithing of the granular FBSR product was investigated to prevent dispersion during transport or burial/storage. Monolithing in an inorganic geopolymer binder, which is

  18. Design method for adsorption beds

    NASA Technical Reports Server (NTRS)

    Blakely, R. L.; Jackson, J. K.

    1970-01-01

    Regenerable adsorption beds for long-term life support systems include synthetic geolite to remove carbon dioxide and silica gel to dehumidify the atmospheric gas prior to its passage through the geolite beds. Bed performance is evaluated from adsorption characteristics, heat and mass transfer, and pressure drop.

  19. Early to Bed, Early to Rise a Back-To-School Challenge

    MedlinePlus

    ... medlineplus.gov/news/fullstory_160532.html Early to Bed, Early to Rise a Back-to-School Challenge ... idea. Allow your kids some quiet time before bed to unwind. "That can include relaxing activities, such ...

  20. The Virtual Test Bed Project

    NASA Technical Reports Server (NTRS)

    Rabelo, Luis

    2003-01-01

    This is a report of my activities as a NASA Fellow during the summer of 2003 at the NASA Kennedy Space Center (KSC). The core of these activities is the assigned project: the Virtual Test Bed (VTB) from the Spaceport Engineering and Technology Directorate. The VTB Project has its foundations in the NASA Ames Research Center (ARC) Intelligent Launch & Range Operations program (ILRO). The objective of the VTB project is to develop a unique collaborative computing environment where simulation models can be hosted and integrated in a seamless fashion. This collaborative computing environment will have as emphasis operational models. This report will focus on the decisions about the different simulation modeling environments considered, simulation platform development, technology and operational models assessment, and computing infrastructure implementation.

  1. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbon (μGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  2. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbon (μGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  3. Wound bed preparation: ultrasonic-assisted debridement.

    PubMed

    Butcher, Gillian; Pinnuck, Loreto

    Wound bed preparation is essential for the healing of wounds. The TIME framework (tissue, infection/inflammation, moisture balance, edge of wound) for wound bed preparation shows the importance of debridement in the treatment of chronic wounds. Debridement involves the removal of devitalised tissue from the wound bed. It also facilitates the removal of biofilms-complex microbial communities that are known to contribute to delayed wound healing