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Sample records for agricultural headwater catchment

  1. Transport and attenuation of chloroacetanilides in an agricultural headwater catchment

    NASA Astrophysics Data System (ADS)

    Lefrancq, Marie; Imfeld, Gwenaël; Millet, Maurice; Payraudeau, Sylvain

    2015-04-01

    Chloroacetanilides (e.g., S-metolachlor and acetochlor) are pre-emergent herbicides used on corn and sugar beet and are applied to bare soil, which is prone to runoff and erosion. Some of these herbicides are chiral and the commercial products can be isomerically enriched in the enantiomer-S compared to the enantiomer-R as an example S-metolachlor 80/20% S to R . Determination of the transport of these herbicides in the dissolved and particulate phases of runoff water and degradation in agricultural catchments is currently lacking. The objectives of this study were i) to quantify over an corn growing season the export of chloroacetanilides and their main degradation products (ethane sulfonic (ESA) and oxanilic acid (OXA) degradates of metolachlor (MESA and MOXA) and acetochlor (AcESA and AcOXA)) in an 47 ha agricultural head-catchment in the dissolved and particulate phases, and ii) to evaluate S-metolachlor biodegradation from its application on the field to its export from the catchment using enantiomer analysis. Runoff, erosion, hydrochemistry and chloroacetanilide transport were evaluated at both the plot and catchment scales. Our results showed that an important amount of the pesticide load is missed when only the dissolved concentration of the parent compound is analysed. The total export coefficients for S-metolachlor and acetochlor and their degradation products were 11.4 and 11.8%, respectively, which includes both the dissolved and particulate loads. The partitioning of S-metolachlor and acetochlor between the dissolved and particulate phases varied widely over time and was linked to the suspended solid concentrations. Detection of S-metolachlor degradation products in runoff water was more frequent compared to that of acetochlor degradation products. Enrichment up to 37% of R-metolachlor was observed during the corn growing season, supporting enantioselective degradation of S-metolachlor. Our field study indicates the potential of enantiomer analyses for

  2. Spatial and temporal water quality dynamics during baseflow in an agricultural headwater catchment

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Weiler, Markus; Saroos, Manuel

    2013-04-01

    Understanding the interaction of time variant source areas and biogeochemical in-stream processes and the determination of resulting spatial and temporal signatures of stream water composition will improve the prediction and management of water quality at the catchment scale. During baseflow periods runoff source areas can change over time depending e.g. on storage depletion rates, actual wetness, groundwater level or local evapotranspiration rates. Due to the resulting space/time variant water fluxes, these effects are also expressed in the physico-chemical composition of surface waters. Unfortunately the resulting signature is often overlain by biogeochemical in-stream processes, which make it difficult to identify physico-chemical signatures of specific runoff source areas. We studied these interactions in a 1.7 km² agricultural headwater catchment. A dense artificial drainage network and a predominantly impervious streambed allowed for detecting distinct locations of groundwater inflow and determining ongoing biogeochemical in-stream processes. The analysis of sub-catchment storage depletion and resulting time variant quantitative and qualitative impacts on stream water composition was based on observations made during 11 catchment wide synoptic sampling campaigns during the summer baseflow period. We measured stream discharges with salt dilution gauging as well as water temperatures (T) and electrical conductivity (EC) upstream, downstream and inside all active drain pipes. During two campaigns we took additional water samples for major ion analysis at all sampling points. Discharges, T and EC stream-network data sets were used to spatially determine groundwater contributions using mixing equations for 2 and 3 components, respectively. Thereby we derived local baseflow recessions in relation to the catchment wide stream discharge. Using a water balance approach we determined active runoff source areas for each drain pipe and identified the dominant land use

  3. A view of annual water quality cycle and inter-annual variations in agricultural headwater catchment (Kervidy-Naizin, France)

    NASA Astrophysics Data System (ADS)

    Aubert, A.; Gascuel-odoux, C.; Merot, P.; Grimaldi, C.; Gruau, G.; Ruiz, L.

    2011-12-01

    between hot and cold years and between wet and dry years can mainly be observed during spring and autumn period, i.e. when combining variations of rainfall and temperature. Further jointed statistical analyses between water chemistry and meteorology have to be carried on. References Molenat, J., Gascuel-Odoux, C., Ruiz, L., and Gruau, G. (2008). Role of water table dynamics on stream nitrate export and concentration. in agricultural headwater catchment (France). Journal of Hydrology 348, 363-378. Morel, B., Durand, P., Jaffrezic, A., Gruau, G., and Molenat, J. (2009). Sources of dissolved organic carbon during stormflow in a headwater agricultural catchment. Hydrological Processes 23, 2888-2901.

  4. Assessment of climate change and increased atmospheric CO2 impacts on water quality in an intensive agricultural headwater catchment

    NASA Astrophysics Data System (ADS)

    Salmon-Monviola, Jordy; Moreau, Pierre; Benhamou, Cyril; Durand, Patrick; Merot, Philippe; Oehler, François; Gascuel-Odoux, Chantal

    2013-04-01

    Climate change and increasing atmospheric CO2 concentration can lead to disturbances in the global hydrological and nitrogen (N) cycling, and losses in catchment systems. Potential impacts on water and N cycling have been studied in large catchments with a variety of land uses but less attention has focused on agricultural headwater catchments. Despite their relatively small dimensions, headwater catchments of 1-10 km² play a dominant role in N transformations in the landscape, and streams in such catchments may have major impacts on downstream water quantity and quality. This issue is particular important for agricultural catchment which have to reach the WFD targets, where land use changes has to be analysed in combination with climate change. The effects of climate change and rising concentrations of atmospheric CO2 have been studied on (1) changes in hydrological and N balance components on a yearly basis and (2) the seasonal dynamics of water and N fluxes. The spatially distributed agro-hydrological model TNT2 (Topography-based nitrogen Transfers and Transformations) driven by ARPEGE (Action de Recherche Petite Echelle Grande Echelle) climate-model outputs from A1B scenario have been applied on the Kervidy-Naizin headwater catchment (western France), a long term hydrological observatory. Consideration of atmospheric CO2 concentration was implemented at two levels in TNT2: i) to account for the CO2 effect on stomatal conductance TNT2; ii) to consider effect of CO2 on biomass growth. Climate data from ARPEGE model, corrected with the quantile-quantile bias correction method, over 30-year simulation periods were used as TNT2 input (Salmon-Monviola et al., in review). With increased CO2, the main trends in water balance were a significant decrease in annual actual evapotranspiration, a moderate decrease in annual discharge and wetland extent, and a decrease in spring and summer of groundwater recharge and soil water content. Not considering the effects of

  5. Nitrate sinks and sources as controls of spatio-temporal water quality dynamics in an agricultural headwater catchment

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Gascuel-Odoux, Chantal; Durand, Patrick; Weiler, Markus

    2016-02-01

    Several controls are known to affect water quality of stream networks during flow recession periods, such as solute leaching processes, surface water-groundwater interactions as well as biogeochemical in-stream turnover processes. Throughout the stream network, combinations of specific water and solute export rates and local in-stream conditions overlay the biogeochemical signals from upstream sections. Therefore, upstream sections can be considered functional units which could be distinguished and ordered regarding their relative contribution to nutrient dynamics at the catchment outlet. Based on snapshot sampling of flow and nitrate concentrations along the stream in an agricultural headwater during the summer flow recession period, we determined spatial and temporal patterns of water quality for the whole stream. A data-driven, in-stream-mixing-and-removal model was developed and applied for analysing the spatio-temporal in-stream retention processes and their effect on the spatio-temporal fluxes of nitrate from subcatchments. Thereby, we have been able to distinguish quantitatively between nitrate sinks, sources per stream reaches, and subcatchments, and thus we could disentangle the overlay of nitrate sink and source signals. For nitrate sources, we determined their permanent and temporal impact on stream water quality and for nitrate sinks, we found increasing nitrate removal efficiencies from upstream to downstream. Our results highlight the importance of distinct nitrate source locations within the watershed for in-stream concentrations and in-stream removal processes, respectively. Thus, our findings contribute to the development of a more dynamic perception of water quality in streams and rivers concerning ecological and sustainable water resource management.

  6. Spatio-temporal variability of the molecular fingerprint of soil dissolved organic matter in a headwater agricultural catchment

    NASA Astrophysics Data System (ADS)

    Jeanneau, Laurent; Pierson-Wickmann, Anne-Catherine; Jaffrezic, Anne; Lambert, Thibault; Gruau, Gérard

    2013-04-01

    Dissolved organic matter (DOM) is implied in (i) ecosystem services such as the support of biodiversity, (ii) the alteration of the drinkable water quality by formation of trihalomethane and (iii) the transfer of micropollutants from soils to rivers. Moreover, since DOM connects soils and oceans that are interacting with the atmosphere, understanding its biogeochemistry will help in investigating the carbon cycle and in creating strategies to mitigate climate change. DOM in headwater stream ecosystems is mainly inherited from allochtonous inputs with different reservoirs being mobilized during storm and interstorm events at the scale of an hydrological year. Those changes in DOM reservoirs, if accompanied by composition and reactivity changes, may impact DOM ecosystem services and drinking water production processes. Elucidating the compositional changes due to changes in the source of DOM in rivers has thus become a important axis of DOM research. The aim of this study is to test the ability of the molecular tools of the organic geochemistry and more specifically the combination of thermochemiolysis and gas chromatography - mass spectrometry (THM-GC-MS) to (i) link the variability of the river DOM composition to different DOM reservoirs in catchment soils and (ii) provide hypothesis on the nature and the mechanisms of formation (microbial growth, litter decomposition) of those reservoirs. This analytical method seems particularly adapted since it allows the differentiation between vegetal and microbial inputs and the determination of the extent of the biodegradation process of biomolecules such as lignin. To test this method, the molecular fingerprint of soil DOM has been investigated in the wetland area of a small (500 ha) agricultural catchment (the so-called Kervidy-Naizin catchment) located in Brittany, western France. The soil DOM was sampled fortnightly at three depths using zero-tension lysimeters during the hydrological year 2010-2011. The samples were

  7. Ecosystem Services Derived from Headwater Catchments

    EPA Science Inventory

    We used data from the USEPA’s wadeable streams assessment (WSA), US Forest Service’s forest inventory and analysis (FIA), and select USFS experimental forests (EF) to investigate potential ecosystems services derived from headwater catchments. C, N, and P inputs to these catchmen...

  8. Guiding soil conservation strategy in headwater mediterranean catchments

    NASA Astrophysics Data System (ADS)

    Ben Slimane, Abir; Raclot, Damien; Evrard, Olivier; Sanaa, Mustapha; Lefèvre, Irène; Le Bissonnais, Yves

    2016-04-01

    Reservoir siltation due to water erosion is an important environmental issue in Mediterranean countries where storage of clear surface water is crucial for their economic and agricultural development. In order to reduce water erosion, this study aimed to design a methodology for guiding the implementation of efficient conservation strategies by identifying the dominant sediment sources in Mediterranean context. To this end, a fingerprinting method was combined with long-term field monitoring of catchment sediment yield in five headwater catchments (0.1-10 km2) equipped with a small reservoir between 1990 and 1995. The five catchments were chosen to cover the large diversity of environmental conditions found along the Tunisian Ridge and in the Cape Bon region. The fingerprinting techniques based on measurements of cesium-137 and Total Organic Carbon within the catchments and in reservoir sediment deposits successfully identified the contribution of rill/interrill and gully/channel erosion to sediment yield at the outlet of five small headwater catchments during the last 15-20 years. Results showed the very large variability of erosion processes among the selected catchments, with rill/interrill erosion contributions to sediment accumulated in outlet reservoirs ranging from 20 to 80%. Overall, rill/interrill erosion was the dominant process controlling reservoir siltation in three catchments whereas gully/channel erosion dominated in the other two catchments. This demonstrates that the dominant erosion process in the Mediterranean regions highly depends on the local environmental context. The lowest rill/interrill erosion contribution (2.2 Mg ha-1 yr-1) in the five catchments remained significantly higher than the tolerable soil loss indicating the severe levels reached by soil erosion along the Tunisian Ridge and in the Cape Bon region. This study also showed that although the implementation of improved topsoil management measures greatly reduced rill

  9. Groundwater flow path dynamics and nitrogen transport potential in the riparian zone of an agricultural headwater catchment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stream riparian zones are often thought of as areas that provide natural remediation for groundwater contaminants, especially agricultural nitrogen (N). While denitrification and vegetative uptake tend to be efficient N removal processes in slow moving shallow groundwater, these mechanisms decrease ...

  10. Temporal trends and relationships between groundwater and surface water nitrate concentrations in headwater agricultural catchments: what can we learn from a monitoring over 20 years?

    NASA Astrophysics Data System (ADS)

    Fovet, O.; Gascuel, C.; Faucheux, M.; Ruiz, L.; Aquilina, L.; Molenat, J.

    2012-04-01

    The intensification of agriculture during the 20th century led to strong issues on water quality related to nutrients enrichments in groundwater and surface water. In this context, Western France is an extreme case regarding to the high nitrate concentrations observed in rivers (around 7 mg N-NO3/l1 in average). In the early 90ies, an Environmental Research Observatory AgrHys has been created and instrumented to investigate the response time of hydro-chemical fluxes to landuse changes in agrohydrosystems. This observatory is part of a French Catchments Network (Critical Zone Observatory), and composed of two sites. Kervidy-Naizin monitoring has been recently analyzed to identify the effect of climatic factors on water quality, while we focus here on Kerbernez site. This site is composed of 5 first-order and adjacent catchments, less than 1 km^2, where land use agricultural practices have been recorded with precision. Hydrological, hydrochemical and climatic data were recorded over the last 20 years. Since 2001, the monitoring was extended to groundwater using piezometric measurements and chemical analyses. Previous studies [1] suggested that nitrate transport was essentially a transport limited process on this site. The long-term and extensive monitoring programs can help us understanding the effect of agricultural practices on nitrate concentration in streams. We reconsider this hypothesis 10 years later by analyzing if the streams nitrate concentrations reacted to the changes in agricultural practices. Different protocols of monitoring (manual vs. automatic measurements) are compared though the annual water fluxes at the outlet in order to estimate the incertitude on water discharge for such small streams. All the water balances computed were not equilibrated suggesting important subsurface flows. The high contribution of the shallow groundwater is confirmed by the hydrochemical data. Mean annual nitrate concentration in the drainage water is computed using two

  11. A synoptic survey of ecosystem services from headwater catchments in the United States (presentation)

    EPA Science Inventory

    Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Water supply per unit catchment area was highest in the Northern Appalachian Mountains and lowest in the Northern Plains. C, ...

  12. A synoptic survey of ecosystem services from headwater catchments in the United States- webinar

    EPA Science Inventory

    Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Water supply per unit catchment area was highest in the Northern Appalachian Mountains and lowest in the Northern Plains. C, ...

  13. Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

    EPA Science Inventory

    We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

  14. Agriculture has changed the amount and composition of dissolved organic matter in Central European headwater streams.

    PubMed

    Graeber, Daniel; Gelbrecht, Jörg; Pusch, Martin T; Anlanger, Christine; von Schiller, Daniel

    2012-11-01

    Dissolved organic matter (DOM) is an important part of the global carbon cycle and significantly influences aquatic ecosystem functions. Recent studies suggest that its amount and composition in freshwaters may be altered by agricultural land use, whereby the influence of preceding in-stream production and processing is not clear. To assess the land use effect on DOM amount and composition for the export from terrestrial to freshwater systems at the land-water interface, we sampled headwater streams draining agricultural and near-pristine catchments (forested and wetland) in the North German plains. To account for spatial and seasonal variation, we conducted a screening of DOM amount (53 sites) and composition (42 sites), and conducted bi-weekly samplings to investigate seasonal variation at eight sites over one year. Concentrations of dissolved organic carbon (DOC) were significantly higher for agricultural and wetland catchments than for forested catchments. Moreover, DOC loads exhibited higher seasonal variation for agricultural and wetland catchments than for forested catchments, which was due to higher variation in discharge. Parallel Factor Analysis revealed that the composition of DOM in agricultural catchments was significantly different from the other studied catchment types, and was characterized by low redox state and high structural complexity. Moreover, a gradient from protein- to humic-like fluorescence significantly separated forested from agricultural and wetland catchments. The contribution of humic-like DOM was strongly and positively related to DOC concentration, suggesting a mechanistic coupling of both. The effects of land use on patterns of DOC concentration and DOM composition were consistent across seasons, implying that land use strongly regulates DOM export. Overall, this study clearly shows the seasonally independent importance of agricultural land use for the amount and composition of DOM fluxes from the terrestrial zone to surface

  15. Before and after integrated catchment management in a headwater catchment: changes in water quality.

    PubMed

    Hughes, Andrew O; Quinn, John M

    2014-12-01

    Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

  16. Before and After Integrated Catchment Management in a Headwater Catchment: Changes in Water Quality

    NASA Astrophysics Data System (ADS)

    Hughes, Andrew O.; Quinn, John M.

    2014-12-01

    Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

  17. Carbon fluxes in an acid rain impacted boreal headwater catchment

    NASA Astrophysics Data System (ADS)

    Marx, Anne; Hintze, Simone; Jankovec, Jakub; Sanda, Martin; Dusek, Jaromir; Vogel, Tomas; van Geldern, Robert; Barth, Johannes A. C.

    2016-04-01

    Terrestrial carbon export via inland aquatic systems is a key process in the budget of the global carbon cycle. This includes loss of carbon to the atmosphere via gas evasion from rivers or reservoirs as well as carbon fixation in freshwater sediments. Headwater streams are the first endmembers of the transition of carbon between soils, groundwater and surface waters and the atmosphere. In order to quantify these processes the experimental catchment Uhlirska (1.78 km2) located in the northern Czech Republic was studied. Dissolved inorganic, dissolved organic and particulate organic carbon (DIC, DOC, POC) concentrations and isotopes were analyzed in ground-, soil -and stream waters between 2014 and 2015. In addition, carbon dioxide degassing was quantified via a stable isotope modelling approach. Results show a discharge-weighted total carbon export of 31.99 g C m-2 yr-1 of which CO2 degassing accounts 79 %. Carbon isotope ratios (δ13C) of DIC, DOC, and POC (in ‰ VPDB) ranged from -26.6 to -12.4 ‰ from -29.4 to -22.7 ‰ and from -30.6 to -26.6 ‰ respectively. The mean values for DIC are -21.8 ±3.8 ‰ -23.6 ±0.9 ‰ and -19.5 ±3.0 ‰ for soil, shallow ground and surface water compartments. For DOC, these compartments have mean values of -27.1 ±0.3 ‰ -27.0 ±0.8 ‰ and -27.4 ±0.7 ‰Ṁean POC value of shallow groundwaters and surface waters are -28.8 ±0.8 ‰ and -29.3 ±0.5 ‰ respectively. These isotope ranges indicate little turnover of organic material and predominant silicate weathering. The degassing of CO2 caused an enrichment of the δ13C-DIC values of up to 6.8 ‰ between a catchment gauge and the catchment outlet over a distance of 866 m. In addition, the Uhlirska catchment has only negligible natural sources of sulphate, yet SO42- accounts for 21 % of major stream water ions. This is most likely a remainder from acid rain impacts in the area.

  18. Conservation implications of amphibian habitat relationships within channelized agricultural headwater streams in the midwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The widespread use of stream channelization and subsurface tile drainage for removing water from agricultural fields has led to the development of numerous channelized agricultural headwater streams within agricultural watersheds of the Midwestern United States. Channelized agricultural headwater s...

  19. Mean transit times in contrasting headwater catchments from southeast Australia determined using Tritium

    NASA Astrophysics Data System (ADS)

    Cartwright, Ian; Morgenstern, Uwe; Irvine, Dylan

    2016-04-01

    Headwater streams contribute a significant proportion of the total discharge of many river systems. However, despite their importance, the time taken for rainfall to pass through the catchment into the streams (the transit time) in headwater catchments is largely unknown as are the catchment characteristics (such as drainage density, topography, landuse, or geology) that determine variations in transit times. Because the peak in Tritium activities in rainfall produced by atmospheric nuclear tests in the1950's and 1960's (the "bomb-pulse") was several orders of magnitude lower in the southern hemisphere than in the northern hemisphere, Tritium activities of remnant bomb pulse water in the southern hemisphere have decayed below those of modern rainfall. This allows mean transit times to be estimated from single Tritium measurements. Here we use Tritium to estimate transit times of water contributing to perennial streams in the adjacent upper catchments of the Yarra and Latrobe Rivers (southeast Australia). Samples were collected at varying flow from six headwater tributary sites in the Latrobe catchment, which is largely forested and four tributaries in the Yarra catchment which has been extensively cleared for dryland agriculture. The lowest Tritium activities were recorded during summer baseflow conditions and are between 1.25 and 1.75 TU, these are significantly below the Tritium activity of local rainfall (~2.8 TU). Mean transit times calculated using an exponential-piston flow lumped parameter model are 21 to 47 years. Tritium activities during the recession periods following winter high flows are higher (1.54 to 2.1 TU), which may reflect either the dilution of a baseflow component with recent surface runoff or mobilisation of different stores of water with different residence times (e.g., from the soils or the regolith) from within the catchment. The variation of major ion concentrations with discharge suggests it is more likely that that different stores of

  20. Runoff responses to forest thinning at plot and catchment scales in a headwater catchment draining Japanese cypress forest

    NASA Astrophysics Data System (ADS)

    Dung, Bui Xuan; Gomi, Takashi; Miyata, Shusuke; Sidle, Roy C.; Kosugi, Kenichiro; Onda, Yuichi

    2012-06-01

    SummaryWe examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catchment M5), and left the control catchment (M4) untreated. In both catchments, we monitored overland flow from hillslope plots and stream runoff from catchments at basin outlets over a 2-year pre-thinning period and a 2-year post-thinning period. Paired catchment analysis revealed that annual catchment runoff increased 240.7 mm after thinning. Delayed runoff increased significantly, while quick runoff followed similar patterns in the pre- and post-thinning periods. Flow duration in the ephemeral channel in catchment M5 increased from 56.9% in the pre-thinning period to 73.3% in the post-thinning period. Despite the changes in hydrological responses at the catchment scale, increases in overland flow were not significant. The increased availability of water in the soil matrix, caused by decreased interception loss and evapotranspiration, increased base flow after thinning. Based on the summarized data of previous studies together with this study, the effects of forest thinning on increases in runoff were less than partial harvesting in which the managed areas were concentrated within a watershed. We demonstrated that the effect of forest thinning was strongly scale dependent, an important finding for optimizing water and forest management in forested watersheds.

  1. Comparison of organic matter composition in agricultural versus forest affected headwaters with special emphasis on organic nitrogen.

    PubMed

    Heinz, Marlen; Graeber, Daniel; Zak, Dominik; Zwirnmann, Elke; Gelbrecht, Joerg; Pusch, Martin T

    2015-02-17

    Agricultural management practices promote organic matter (OM) turnover and thus alter both the processing of dissolved organic matter (DOM) in soils and presumably also the export of DOM to headwater streams, which intimately connect the terrestrial with the aquatic environment. Size-exclusion chromatography, in combination with absorbance and emission matrix fluorometry, was applied to assess how agricultural land use alters the amount and composition of DOM, as well as dissolved organic nitrogen (DON) forms in headwater streams, including temporal variations, in a temperate region of NE Germany. By comparing six agriculturally and six forest-impacted headwater streams, we demonstrated that agriculture promotes increased DOC and DON concentrations, entailing an even more pronounced effect on DON. The major part of DOC and DON in agricultural and forest reference streams is exported in the form of humic-like material with high molecular weight, which indicates terrestrial, i.e., allochthonous sources. As an obvious difference in agricultural streams, the contribution of DOC and particularly DON occurring in the form of nonhumic high-molecular-weight, presumably proteinous material is clearly elevated. Altogether, DOM in agricultural headwaters is mainly complex-soil-derived and aromatic material with a low C:N ratio, which is more microbial processed than its counterpart from forest reference catchments. Our results emphasize the importance of agricultural land use on DOM loss from soils and identify agricultural soils as important DOC and particularly DON sources to headwater streams.

  2. Natural flood risk management in flashy headwater catchments: managing runoff peaks, timing, water quality and sediment regimes

    NASA Astrophysics Data System (ADS)

    Wilkinson, Mark; Addy, Steve; Ghimire, Sohan; Kenyon, Wendy; Nicholson, Alex; Quinn, Paul; Stutter, Marc; Watson, Helen

    2013-04-01

    Over the past decade many European catchments have experienced an unusually high number of flood events. A large number of these events are the result of intense rainfall in small headwater catchments which are dominated by surface runoff generation, resulting in flash flooding of local communities. Soil erosion and related water quality issues, among others, are typically associated with such rapid runoff generation. The hazard of flooding is increasing owing to impacts of changing climatic patterns (including more intense summer storms), intensification of agriculture within rural catchments and continued pressure to build on floodplains. Concurrently, the cost of constructing and maintaining traditional flood defences in small communities outweigh the potential benefits. Hence, there is a growing interest in more cost effective natural approaches that also have multipurpose benefits in terms of sediment, water quality, and habitat creation. Many catchments in Europe are intensively farmed and there is great potential for agriculture to be part of the solution to flood risk management. Natural flood management (NFM) is the alteration, restoration or use of landscape features with the aim of reducing flood risk by slowing down, storing (and filtering) rapid surface runoff. NFM includes measures such as temporarily storing water in ponds/wetlands, increasing soil infiltration, planting trees on floodplains and within catchments, re-meandering and wood placements in streams/ditches. In this presentation we highlight case studies from densely instrumented research sites across the UK (which could be typical of many European catchments) where NFM measures have been installed in small scale flashy catchments. The presentation will give an overview of the function of these measures in these catchments and how other multiple benefits are being accrued. Study catchments include the headwater catchments of the Bowmont (3 to 8 km2) and Belford Burn (6 km2) catchments. These

  3. Peak Flow Responses and Recession Flow Characteristics After Thinning of Japanese Cypress Forest in a Headwater Catchment

    EPA Science Inventory

    We evaluated the effects of forest thinning on peak flow and recession characteristics of storm runoff in headwater catchments at Mie Prefecture, Japan. In catchment M5, 58.3% of stems were removed, whereas catchment M4 remained untreated as a control catchment. Storm precipitati...

  4. Estimation of pesticide and transformation product export pathways in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Gassmann, Matthias; Olsson, Oliver; Stamm, Christian; Weiler, Markus; Lange, Jens; Kümmerer, Klaus

    2014-05-01

    Following their application, pesticide residues are exported towards rivers along several hydrological pathways in agricultural areas. The importance of each pathway is influenced by the substances' physico-chemical characteristics, mainly sorption and degradation. Incomplete mineralization results in the formation of transformation products (TPs) which have generally different environmental fate characteristics than their parent compounds (PCs). Therefore, the export pathways of pesticides and their transformation products towards rivers may also be different. In order to investigate this hypothesis, we extended a distributed process-based hydrological model (ZIN-AgriTra) by the environmental fate of pesticides and their TPs. The process-based nature of the model allowed for an analysis of PC and TP export pathways including overland flow, lateral preferential flow in soils and soil water flow to tile drains. The model was applied to a Swiss headwater catchment using three pesticides and their TPs as test substances. It was successfully calibrated to three sampling stations in the catchment. At the end of the simulated three-months period, most of the applied pesticides were either fully mineralized or incompletely transformed. Less than 2% of each pesticide was exported to the river as PC or TP. Although all three pesticides could be classified as slightly mobile they remained in the top soil layer during the whole period, whereas the more mobile TPs were additionally leached through the soil towards tile drains. Accordingly, PCs were exported largely by surface runoff, while a larger share of TPs was exported via tile drains. Additionally, the delayed formation and degradation of TPs led to an export under different hydrological conditions resulting in an increased subsurface export of TPs towards the end of the simulation period. A consequence of the different export pathways of PCs and TPs could be shown by an assessment of critical source areas (CSA) in the

  5. A synoptic survey of ecosystem services from headwater catchments in the United States

    EPA Science Inventory

    We combined data collected from 568 headwater streams as a part of the US Environmental Protection Agency’s National Rivers and Streams Assessment (NRSA) with catchment attributes related to the production of the ecosystem services of water supply, carbon, nitrogen, and phosphoru...

  6. Variability of water quality across headwater catchments with distinct soils and hydrologic systems in central Missouri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface water and groundwater contamination by herbicides and fertilizers continues to be a major water quality problem in central Missouri. The purpose of this study was to examine spatial variability of water quality among three different headwater catchments – Goodwater Creek Experimental Watersh...

  7. Understanding drivers of the export of dissolved organic carbon from a German headwater catchment using Generalised Additive Models

    NASA Astrophysics Data System (ADS)

    Selle, Benny; Musolff, Andreas; Tittel, Jörg

    2016-04-01

    In the literature, several causes of recently increasing concentrations of dissolved organic carbon (DOC) in headwaters across eastern North America and northern and central Europe have been debated. One likely driver of the widespread increase of DOC concentrations since the early 1990s are decreasing depositions of acid rain resulting in an increased solubility of organic carbon compounds including humic acids. Here, we tested the hypothesis if the reduced availability of nitrate stimulated the microbial reduction of ferric iron soil minerals and the mobilisation of DOC. Forested catchments are relatively unaffected by agricultural and urban nitrate inputs. In these catchments, decreasing depositions often resulted in a reduced availability of nitrate, which are preferred electron acceptors in microbial decomposition processes. As ferric iron minerals act as efficient sorbents of organic compounds in soils its reduction may cause a release of humic substances and hence an export of DOC. To test this hypothesis, time series of DOC, dissolved iron and nitrate from a forested headwater catchment in Germany were examined using Generalised Additive Models. We found that rising DOC concentrations most likely resulted from a reductive dissolution of iron(III) minerals in soils and the associated mobilisation of adsorbed organic carbon. Phosphate, which can trigger undesired algal growth and is also known to be adsorbed by particulate iron(III), was released as well.

  8. Influence of catchment land cover on stoichiometry and stable isotope compositions of basal resources and macroinvertebrate consumers in headwater streams

    EPA Science Inventory

    Anthropogenic land use affects aquatic landscapes. For example, landscape-level conversion to urban or agricultural land can heavily influence nutrient cycles in headwater streams via increased nutrient loading and altered hydrologic patterns. Recent studies in headwater streams ...

  9. Impacts of Climate Change on Groundwater Recharge and Streamflow in Headwater Catchments in the Yakima River Basin

    NASA Astrophysics Data System (ADS)

    Nguyen, T. T.; Adam, J. C.

    2015-12-01

    Headwater catchments are important sources of surface water supply, groundwater recharge and, thus, groundwater supply for agricultural activities in the Yakima River Basin (YRB, one of the most important agricultural basins in the western U.S). These catchments are, however, vulnerable to projected climate change in future decades, particularly if their runoff is dominated by snowmelt. The goal of this study is to assess the potential impacts of climate change on the temporal and spatial distributions of groundwater recharge and streamflow in three headwater catchments in the YRB. A Regional Hydro-Ecologic Simulation System ("RHESSys") is calibrated and evaluated with a global optimization tool ("Covariance Matrix Adaptation Evolution Strategy - CMA-ES") using 27 years of observation data from 1979 to 2005. Statistically downscaled climate projections for the 2050s from four global climate models driven by two different representative concentration pathways, RCP4.5 and RCP8.5 are used to predict future hydrologic changes. Our preliminary results show an increase in annual recharge between 2% and 13%, as well as in streamflow between 1% and 17%. Seasonal changes of recharge and streamflow are more pronounced with an increase up to 210% in winters and a decrease as high as 60% in summers in the 2050s. Both recharge and streamflow projections indicate timing shifts in all three catchments. The outcome from this study will be an integral part of a future study which investigates the impacts of climate change on surface water vulnerability due to supplemental pumping, potential recharge changes and related surface-groundwater interactions in the YRB using an integrated modeling approach that consists of three models: RHESSys, a groundwater model (MODFLOW) and a river and reservoir management model (RiverWare).

  10. Characterization of hydrologic inputs and streamflow pathways in headwater catchments of Boulder Creek Watershed, Colorado

    NASA Astrophysics Data System (ADS)

    Cowie, R. M.; Williams, M. W.; Mills, T. J.

    2012-12-01

    Streamflow pathways were investigated using isotopic and geochemical tracers in two gauged headwater catchments located at different elevations within the forested area of Boulder Creek Watershed, Colorado. Using diagnostic tools of mixing models indicates that both catchments fit reasonable well to a 1-D (two endmember) model for streamflow generation. End member mixing analysis (EMMA) suggests that streamflow at the lower elevation Gordon Gulch catchment (mean elevation 2627 m) was a combination of shallow subsurface flow and groundwater with limited influence from direct runoff. Steamflow at the higher elevation Como Creek catchment (mean elevation 3230 m) was a combination of runoff from snowmelt and groundwater. During the study period the total annual precipitation and the amount of precipitation falling as snow increased with elevation from 456 mm (41% snow) at Gordon Gulch to 804 mm (71% snow) at Como Creek. The resulting increase in winter snow accumulation at Como Creek demonstrates differences in timing and magnitude of hydrologic inputs between the two catchments and provides a potential driver for the differences in streamflow pathways. These results highlight the importance of understanding variations in streamflow pathways in relation to climatic variations across headwater mountain catchments. The broader impacts of streamflow pathway variations on steam nutrients will also be addressed.

  11. Influence of instream habitat and water chemistry on amphibians within channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The widespread use of stream channelization and subsurface tile drainage for draining agricultural fields has led to the development of numerous channelized agricultural headwater streams within agricultural watersheds of the Midwestern United States, Canada, and Europe. Channelized agricultural he...

  12. Investigation of Biogeochemical Functional Proxies in Headwater Streams Across a Range of Channel and Catchment Alterations

    NASA Astrophysics Data System (ADS)

    Berkowitz, Jacob F.; Summers, Elizabeth A.; Noble, Chris V.; White, John R.; DeLaune, Ronald D.

    2014-03-01

    Historically, headwater streams received limited protection and were subjected to extensive alteration from logging, farming, mining, and development activities. Despite these alterations, headwater streams provide essential ecological functions. This study examines proxy measures of biogeochemical function across a range of catchment alterations by tracking nutrient cycling (i.e., inputs, processing, and stream loading) with leaf litter fall, leaf litter decomposition, and water quality parameters. Nutrient input and processing remained highest in second growth forests (the least altered areas within the region), while recently altered locations transported higher loads of nutrients, sediments, and conductivity. Biogeochemical functional proxies of C and N input and processing significantly, positively correlated with rapid assessment results (Pearson coefficient = 0.67-0.81; P = 0.002-0.016). Additionally, stream loading equations demonstrate that N and P transport, sediment, and specific conductivity negatively correlated with rapid assessment scores (Pearson coefficient = 0.56-0.81; P = 0.002-0.048). The observed increase in stream loading with lower rapid assessment scores indicates that catchment alterations impact stream chemistry and that rapid assessments provide useful proxy measures of function in headwater ecosystems. Significant differences in nutrient processing, stream loading, water quality, and rapid assessment results were also observed between recently altered (e.g., mined) headwater streams and older forested catchments (Mann-Whitney U = 24; P = 0.01-0.024). Findings demonstrate that biogeochemical function is reduced in altered catchments, and rapid assessment scores respond to a combination of alteration type and recovery time. An analysis examining time and economic requirements of proxy measurements highlights the benefits of rapid assessment methods in evaluating biogeochemical functions.

  13. Reach-scale geomorphic differences between headwater streams draining mountaintop mined and unmined catchments

    NASA Astrophysics Data System (ADS)

    Jaeger, Kristin L.

    2015-05-01

    Mountaintop surface mining (MTM) is a controversial coal extraction method commonly practiced in the central and southern Appalachian Mountains, USA, that drastically reengineers previously steep, forested landscapes and alters sediment and water delivery processes to and along headwater channels draining mined areas. Although sediment delivery and hydrologic response from MTM operations remain highly variable and poorly resolved, the inherent close coupling between hillslopes and headwater channels is expected to result in geomorphic differences in stream channels draining MTM landscapes relative to unmined landscapes. Dedicated geomorphic studies are severely lacking in comparison to extensive research on water quality impacts of MTM. This study reports moderate geomorphic differences between headwater (catchment area <~ 6 km2) stream channels draining MTM and unmined catchments in tributaries of the Mud River in southern West Virginia. Univariate and multivariate analyses indicate that MTM streams are characterized by deeper maximum channel depths, smaller width-to-depth ratios, increased bedrock exposure along the streambed, and increased frequency of very fine silt and sand deposition relative to channels draining unmined catchments. Geomorphic differences are most pronounced for streams draining the smallest catchment areas (< 3.5 km2). Collectively, geomorphic differences provide evidence for relatively rapid channel adjustment of accelerated bedrock incision attributed to potential increased hydraulic driving forces and altered sediment regimes in MTM channels, notably sustained delivery of very fine sediment and potentially reduced coarse sediment delivery. More rapid delivery and transfer of water in addition to excess delivery of very fine sediments to and through headwater channels will have consequences to flooding and water quality in the short term and landscape evolution processes over longer time scales. Given the extent of MTM operations in this

  14. Unraveling soil moisture responses to storms and relationships to runoff in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Singh, N.

    2015-12-01

    Soil moisture exhibits complex spatiotemporal patterns, both laterally across landscapes and vertically within soil profiles. These patterns of soil moisture can have strong influences on runoff generation, especially in catchments having large capacities for soil water storage and transmission. The body of literature on runoff generation is expansive, yet we still have a great deal to learn about how the spatial and temporal heterogeneity of soil moisture influences catchment-scale hydrologic responses to storm events. With this in mind, we investigated soil moisture responses to storm events across several landscape positions in a steep, forested headwater catchment. We measured volumetric water content (VWC) continuously for two years at 45 points representing different combinations of landscape position and soil depth within a 13 ha catchment at Coweeta Hydrologic Laboratory in the Southern Appalachian Mountains. We also monitored shallow groundwater levels at six locations within the catchment along with runoff at the catchment outlet. To investigate soil moisture response during events, we assessed absolute change in magnitude of VWC (Δs) and lag time (Δt) between peak VWC and peak precipitation for 39 events during the two-year study period. Our results showed that storm depth and antecedent moisture explained some of the spatiotemporal patterns of Δs; however, the explanatory power varied with the hillslope and season. Furthermore, we did not detect topographic control of Δs or Δt at most of the locations monitored. By evaluating the sequence of Δt, groundwater response, and runoff response for each storm, we characterized the hydrologic behavior of the study hillslopes for the 39 storm events.The characterization of hydrologic behavior reveals interrelationships between soil moisture and shallow groundwater, and their combined influence on runoff at the catchment outlet. This work provides new insights on links between the spatiotemporal variability

  15. Environmental care in agricultural catchments: Toward the communicative catchment

    NASA Astrophysics Data System (ADS)

    Martin, Peter

    1991-11-01

    Substantial land degradation of agricultural catchments in Australia has resulted from the importation of European farming methods and the large-scale clearing of land. Rural communities are now being encouraged by government to take responsibility for environmental care. The importance of community involvement is supported by the view that environmental problems are a function of interactions between people and their environment. It is suggested that the commonly held view that community groups cannot care for their resources is due to inappropriate social institutions rather that any inherent disability in people. The communicative catchment is developed as a vision for environmental care into the future. This concept emerges from a critique of resource management through the catchment metaphors of the reduced, mechanical, and the complex, evolving catchment, which reflect the development of systemic and people-centered approaches to environmental care. The communicative catchment is one where both community and resource managers participate collaboratively in environmental care. A methodology based on action research and systemic thinking (systemic action research) is proposed as a way of moving towards the communicative catchment of the future. Action research is a way of taking action in organizations and communities that is participative and informed by theory, while systemic thinking takes into account the interconnections and relationships between social and natural worlds. The proposed vision, methodology, and practical operating principles stem from involvement in an action research project looking at extension strategies for the implementation of total catchment management in the Hunter Valley, New South Wales.

  16. Surface fluxes and water balance of spatially varying vegetation within a small mountainous headwater catchment

    NASA Astrophysics Data System (ADS)

    Flerchinger, G. N.; Marks, D.; Reba, M. L.; Yu, Q.; Seyfried, M. S.

    2010-06-01

    Precipitation variability and complex topography often create a mosaic of vegetation communities in mountainous headwater catchments, creating a challenge for measuring and interpreting energy and mass fluxes. Understanding the role of these communities in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. The focus of this paper was: (1) to demonstrate the utility of eddy covariance (EC) systems in estimating the evapotranspiration component of the water balance of complex headwater mountain catchments; and (2) to compare and contrast the seasonal surface energy and carbon fluxes across a headwater catchment characterized by large variability in precipitation and vegetation cover. Eddy covariance systems were used to measure surface fluxes over sagebrush (Artemesia arbuscula and Artemesia tridentada vaseyana), aspen (Populus tremuloides) and the understory of grasses and forbs beneath the aspen canopy. Peak leaf area index of the sagebrush, aspen, and aspen understory was 0.77, 1.35, and 1.20, respectively. The sagebrush and aspen canopies were subject to similar meteorological forces, while the understory of the aspen was sheltered from the wind. Missing periods of measured data were common and made it necessary to extrapolate measured fluxes to the missing periods using a combination of measured and simulated data. Estimated cumulative evapotranspiratation from the sagebrush, aspen trees, and aspen understory were 384 mm, 314 mm and 185 mm. A water balance of the catchment indicated that of the 699 mm of areal average precipitation, 421 mm was lost to evapotranspiration, and 254 mm of streamflow was measured from the catchment; water balance closure for the catchment was within 22 mm. Fluxes of latent heat and carbon for all sites were minimal through the winter. Growing season fluxes of latent heat and carbon were consistently higher above the aspen canopy than from the

  17. Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia

    NASA Astrophysics Data System (ADS)

    Cartwright, I.; Morgenstern, U.

    2015-06-01

    Headwater streams contribute a significant proportion of the total flow to many river systems, especially during summer low-flow periods. However, despite their importance, the time taken for water to travel through headwater catchments and into the streams (the transit time) is poorly constrained. Here, 3H activities of stream water are used to define transit times of water contributing to streams from the upper reaches of the Ovens River in southeast Australia at varying flow conditions. 3H activities of the stream water varied from 1.63 to 2.45 TU, which are below the average 3H activity of modern local rainfall (~3 TU). The highest 3H activities were recorded following higher winter flows and the lowest 3H activities were recorded at summer low-flow conditions. Variations of major ion concentrations and 3H activities with streamflow imply that different stores of water from within the catchment (e.g. from the soil or regolith) are mobilised during rainfall events rather than there being simple dilution of an older groundwater component by event water. Mean transit times calculated using an exponential-piston flow model range between 5 and 31 years and are higher at summer low-flow conditions. Mean transit times calculated using other flow models (e.g. exponential flow or dispersion) are similar. There are broad correlations between 3H activities and the percentage of rainfall exported from each catchment and between 3H activities and Na and Cl concentrations that allow first-order estimates of mean transit times in adjacent catchments or at different times in these catchments to be made. Water from the upper Ovens River has similar mean transit times to the headwater streams implying there is no significant input of old water from the alluvial gravels. The observation that the water contributing to the headwater streams in the Ovens catchment has a mean transit time of years to decades implies that these streams are buffered against rainfall variations on

  18. Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia

    NASA Astrophysics Data System (ADS)

    Cartwright, I.; Morgenstern, U.

    2015-09-01

    Headwater streams contribute a significant proportion of the total flow to many river systems, especially during summer low-flow periods. However, despite their importance, the time taken for water to travel through headwater catchments and into the streams (the transit time) is poorly understood. Here, 3H activities of stream water are used to define transit times of water contributing to streams from the upper reaches of the Ovens River in south-east Australia at varying flow conditions. 3H activities of the stream water varied from 1.63 to 2.45 TU, which are below the average 3H activity of modern local rainfall (2.85 to 2.99 TU). The highest 3H activities were recorded following higher winter flows and the lowest 3H activities were recorded at summer low-flow conditions. Variations of major ion concentrations and 3H activities with streamflow imply that different stores of water from within the catchment (e.g. from the soil or regolith) are mobilised during rainfall events rather than there being simple dilution of an older groundwater component by event water. Mean transit times calculated using an exponential-piston flow model range from 4 to 30 years and are higher at summer low-flow conditions. Mean transit times calculated using other flow models (e.g. exponential flow or dispersion) are similar. There are broad correlations between 3H activities and the percentage of rainfall exported from each catchment and between 3H activities and Na and Cl concentrations that allow first-order estimates of mean transit times in adjacent catchments or at different times in these catchments to be made. Water from the upper Ovens River has similar mean transit times to the headwater streams implying there is no significant input of old water from the alluvial gravels. The observation that the water contributing to the headwater streams in the Ovens catchment has a mean transit time of years to decades implies that these streams are buffered against rainfall variations on

  19. Hydrochemical analysis of stream water in a tropical, mountainous headwater catchment in northern Thailand

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, C.; Ingwersen, J.; Sangchan, W.; Sukvanachaikul, Y.; Uhlenbrook, S.; Streck, T.

    2010-03-01

    Land use in the vulnerable mountainous parts of the Mae Sa watershed, northern Thailand, has been changed from subsistence agriculture to market-driven production within the past decades. This change is reflected in an increased application of agrochemicals on agricultural areas to secure yields and control pests. Our study site is a steep and fast-responding headwater catchment (77 km2), which transfers agrochemicals that might get lost from soils to waters quickly to the lowlands posing the risk of environmental contamination. This work describes the study, which has been carried out in a subcatchment (7 km2) of the Mae Sa watershed to identify runoff generation processes and contributing flow paths to encircle potential flow paths of pesticides leaching from soil to surface water. We observed three events during the rainy seasons in 2007 and 2008, which were analysed on major ions and EC at high temporal resolution. Based on the samples a two-component hydrograph separation was carried out for three events. For two out of the three events a three-component hydrograph separation was performed to identify the contributions of baseflow, interflow and surface runoff. Baseflow remained the dominant flow fraction, but interflow outshined surface runoff in its amount. Interflow could be observed at the hillslope seeping from the soil in 2007, but not in 2008. We suggest, that interflow highly depends on a constant input of rainfall and requires a certain minimum amount of rainfall per season to be triggered and sustained. Former studies found that pesticides mainly get lost by interflow in this area. Hence, we can point out that pesticide leaching risk is particularly high after a certain amount of rainfall. Critical conditions are therefore mainly present, when the soil layers are close to saturation but not, when these layers are generated or degenerated.

  20. Examining the effects of forest thinning on runoff responses at different catchments scales in forested headwaters

    NASA Astrophysics Data System (ADS)

    Dung, B. X.; Gomi, T.; Onda, Y.; Kato, H.; Hiraoka, M.

    2012-12-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefectures for examining the effects of forest thinning on runoff generation at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We also monitored nested catchments within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to July 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on runoff generation at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning responses. Paired-catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 517 mm in K2-3 and 487 mm in K2-4 after the thinning. Both quick and delayed runoff components only increased significantly in the larger catchments of K2-1 and K2-2, while only delayed runoff components of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Increases of quick runoff in large catchments could be associated with quick runoff response to soil surface compaction by line thinning and skid trail installation. Increases of delayed runoff in small catchment may be associated with increase in net precipitation and decrease in evapotranspiration. Our finding showed that changes in internal hydrological flow pathways and associated changes in runoff components due to forest harvesting differ depending on the catchment sizes.

  1. Storage controls on the generation of double peak hydrographs in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Martínez-Carreras, Núria; Hissler, Christophe; Gourdol, Laurent; Klaus, Julian; Juilleret, Jérôme; Iffly, Jean François; Pfister, Laurent

    2016-12-01

    Double peak hydrographs are widespread phenomena but poorly understood mechanistically. In many cases, saturation-excess overland flow in the near-stream areas is assumed to control the initial peak, while the delayed peak is explained by subsurface flow in the soil or sediment cover or groundwater flow on fractured bedrock. Here we explore the mechanisms that control the generation of double peak hydrographs in a forested headwater catchment. We made use of the extensive high-resolution hydrometric time series collected in the catchment to estimate catchment storage and causal linkages. We found that double peak hydrographs occurred only after a certain amount of catchment storage was exceeded. The amount of this storage threshold was consistent over a 3-year period. The non-linear relationship between storage and discharge led to hysteretic relationships between both variables, and these hysteretic relationships were different for the different hydrograph types (single or double peak hydrographs). Discharge peaked before catchment storage during single peak hydrographs suggesting that single peaks were mainly generated by water quickly reaching the stream during precipitation pulses. It was catchment storage that peaked first during double peak hydrographs and consequently generated the delayed peak in the hydrograph. Our results also showed that double peak hydrographs were controlled in different proportions by contrasting landscape units (defined along a hillslope sequence). Hillslopes were connected to the stream at low discharge values, whereas the plateau dominated discharge generation when storage reached a certain threshold value.

  2. Effects of evapotranspiration on baseflow in a tropical headwater catchment

    NASA Astrophysics Data System (ADS)

    Cadol, Daniel; Kampf, Stephanie; Wohl, Ellen

    2012-09-01

    SummaryDiel cycles in stream discharge during baseflow periods in a headwater stream in La Selva Biological Station, Costa Rica, a tropical wet forest site, appear to be associated with groundwater withdrawal by the forest for evapotranspiration (ET). Analysis of the cycles indicates a strong correlation of stage change with ET demand, similar to the variation found in riparian water table elevation by previous researchers. Links between daily forest ET demand cycles and stream discharge cycles have been reported in temperate humid and semi-arid regions, but the frequent flood hydrographs of the wet tropics tend to obscure this daily signal. This study modifies and combines two established empirical methods for analyzing the diel ET signal in streamflow which lead to estimates of riparian ET derived from groundwater (ETG) at hourly time scales and spatial extent of the riparian area. The model has a direct dependence on the estimate of specific yield, a difficult to constrain parameter, which we estimate from previously published soil analyses. For the six baseflow periods analyzed, the model estimates groundwater ET losses ranging from 1.8 to 3.9 mm/day within the riparian area. These estimates are 52-81% of the total ET estimated with the Penman-Monteith equation (ETPM). The signal of ETG in the stream lags ETPM by 1.5-3 h, with apparent peak decay and signal duration lengthening during propagation. Model results indicate that the area of the riparian zone that influences streamflow by means of ET withdrawal increases with stream stage and ranges from 2.5% to 6.6% of the total basin area. Variations in the rate of change of nightly stream stage recovery suggest possible variations in the relative importance of subsurface hydraulic properties. At high stages, the rate of stream stage recovery from ET losses decreases throughout the night, whereas at low stages the rate of stream stage recovery increases throughout the night. Future work with numerical models could

  3. Discriminating anthropogenic climate change from natural climate oscillation signals in dissolved organic matter export from headwater catchments.

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Girma, S.; Quick, C.

    2012-12-01

    Headwater catchments are potential sentinels for climate change because their hydrology and biogeochemistry respond to changing environmental conditions at scales appropriate to changes in both weather and climate. Scientific investigations focusing on changes in climate-driven environmental change would benefit by understanding changes in the export pattern of dissolved organic matter, "DOM signatures", from headwater catchments. However, climatic change has complex influences on headwater catchment dynamics, and to determine the effects of climate change, we must be able to discriminate between anthropogenic climate warming (non-stationary linear trends) and natural climate oscillation (stationary oscillating cycles) signals within catchment DOM yields from catchments. We present an analytical framework based on wavelet theory for analyzing non-stationary and stationary signals in yearly time series of DOM yields. This analytical framework was used to test the following hypotheses: That yearly DOM yields in headwater catchments contain both non-stationary and stationary climate signals; That non-stationary signals are greater than stationary ones; And that the effects of these signals are greater in catchments with lower rates of change in water loading and lower water storage capacity (i.e., are more directly linked to atmospheric conditions). We applied this framework on the yearly time series of DOM yield from catchments in the Turkey Lakes Watershed in Ontario, Canada and show that DOM signals appear "decoupled". In all catchments, dissolved organic carbon (DOC) showed no non-stationary (declining trends) despite showing declining yearly water yields, but catchments with relatively lower water loading (lower elevation on windward side of mountain) showed stronger and larger DOC export than those with higher water loading (high elevation on same side of mountain). In contrast, catchments showed both significant declining trends and oscillating cycles in yearly

  4. Annual and seasonal differences in pesticide mixtures within channelized agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Only a limited amount of information on pesticide mixtures within agricultural headwater streams is available. A greater understanding of the characteristics of pesticide mixtures and their spatial and temporal trends within agricultural headwater streams is needed to evaluate the risks of pesticid...

  5. Examining the effects of forest thinning on hydrological processes at different catchment scales in forested headwater

    NASA Astrophysics Data System (ADS)

    Dung, Bui Xuan; Gomi, Takashi; Onda, Yuichi; Kato, Hiroaki; Hiraoka, Marino

    2013-04-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefecture for examining the effects of forest thinning on hydrological processes at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We monitored nested catchment within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to December 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on hydrological processes at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning behaviors. Paired catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 528 mm in K2-3, and 566 mm in K2-4 during the post-thinning period. Greater increase of flow in largest catchment (K2-1) was be due to the contribution of increased delayed flow from infiltrated water, reappearing as surface flow (i.e., quick flow) in the lower parts of the catchment, caused by harvested activities (logging, road, skid trail). Because both quick and delayed flows increased significantly in the larger catchments of K2-1 and K2-2, while only delayed flow of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Delayed flow also increased greater in K2-3 and K2-4, smaller in K2-2 but greatest in K2-1. Moreover, the increasing contributions to runoff from deeper groundwater sources that are recharged in upslope subcatchments caused increase amount of flow. This was explained when increase of annual base flow (i.e., bedrock flow) of zero-order catchments

  6. Are All Headwater Catchments the Same? Elevational Controls on Organic and Inorganic Nutrients in Headwater Catchments in the Boulder Creek Watershed, Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Parman, J.; Williams, M. W.

    2009-12-01

    High-elevation ecosystems have become the focus of recent biogeochemical research due to their unique and complex processes, but also because these systems may serve as an early warning system for the potential effects of climate change. In the Colorado Front Range, it is expected that alpine areas will continue to experience greater annual precipitation, as well as an increase in atmospheric deposition of inorganic nitrogen (Williams and Tonnessen, 2000). Past studies have shown that these mountain systems tend to amplify such environmental changes in specific areas of the landscape. The Landscape Continuum Model (LCM, Seastedt et al., 2004) proposed a conceptual framework for how mountain ecosystems accumulate and redistribute exogenous material from the atmosphere and endogenous material derived from the mountain itself, emphasizing the importance of transport processes and redeposition of nutrients and water across highly varying and complex terrain. Here, we test the LCM by comparing and contrasting changes in organic and inorganic nutrients in stream waters of headwater catchments along an elevational gradient in the Colorado Front Range. We simultaneously collected water samples at four gauged headwater catchments: (1) Green Lakes Valley (3,500 m); (2) Como Creek (2,900 m); Gordon Gulch (2,400 m); and Betasso (1,830 m). All water samples were analyzed for DOC, DON, DOP, nitrate, and ammonium. Additionally, spectroscopic techniques were used to determine the quality of DOC. These measurements, along with supporting information on soil C:N ratios and climate data, allow us to determine how elevational position controls: (a) the redistribution of exogenous materials from the regional environment such as nitrate in wetfall; and (b) endogenous sources originating from montane areas such as DOC and DON, while controlling for catchment size, aspect, and underlying geology. Seastedt, T. R., W. D. Bowman, T. N. Caine, D. McKnight, A. Townsend & M. W. Williams (2004

  7. Model-based estimation of pesticides and transformation products and their export pathways in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Gassmann, M.; Stamm, C.; Olsson, O.; Lange, J.; Kümmerer, K.; Weiler, M.

    2013-12-01

    Pesticides applied onto agricultural fields are frequently found in adjacent rivers. To what extent and along which pathways they are transported is influenced by intrinsic pesticide properties such as sorption and degradation. In the environment, incomplete degradation of pesticides leads to the formation of transformation products (TPs), which may differ from the parent compounds regarding their intrinsic fate characteristics. Thus, the export processes of TPs in catchments and streams may also be different. In order to test this hypothesis, we extended a distributed hydrological model by the fate and behaviour of pesticides and transformation products and applied it to a small, well-monitored headwater catchment in Switzerland. The successful model evaluation of three pesticides and their TPs at three sampling locations in the catchment enabled us to estimate the quantity of contributing processes for pollutant export. Since all TPs were more mobile than their parent compounds (PCs), they exhibited larger fractions of export via subsurface pathways. However, besides freshly applied pesticides, subsurface export was found to be influenced by residues of former applications. Export along preferential flow pathways was less dependent on substance fate characteristics than soil matrix export, but total soil water flow to tile drains increased more due to preferential flow for stronger sorbing substances. Our results indicate that runoff generation by matrix flow to tile drains gained importance towards the end of the modelling period whereas the contributions from fast surface runoff and preferential flow decreased. Accordingly, TPs were to a large extent exported under different hydrological conditions than their PCs, due to their delayed formation and longer half-lives. Thus, not only their different intrinsic characteristics but also their delayed formation could be responsible for the fact that TPs generally took different pathways than their PCs. We suggest

  8. Model-based estimation of pesticides and transformation products and their export pathways in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Gassmann, M.; Stamm, C.; Olsson, O.; Lange, J.; Kümmerer, K.; Weiler, M.

    2013-07-01

    Pesticides applied onto agricultural fields are frequently found in adjacent rivers. To what extent and along which pathways they are transported is influenced by intrinsic pesticide properties such as sorption and degradation. In the environment, incomplete degradation of pesticides leads to the formation of transformation products (TPs), which may differ from the parent compounds regarding their intrinsic fate characteristics. Thus, the export processes of TPs in catchments and streams may also be different. In order to test this hypothesis, we extended a distributed hydrological model by the fate and behaviour of pesticides and transformation products and applied it to a small, well-monitored headwater catchment in Switzerland. The successful model evaluation of three pesticides and their TPs at three sampling locations in the catchment enabled us to estimate the quantity of contributing processes for pollutant export. Since all TPs were more mobile than their parent compounds (PCs), they exhibited larger fractions of export via subsurface pathways. However, besides freshly applied pesticides, subsurface export was found to be influenced by residues of former applications. Export along preferential flow pathways was less dependent on substance fate characteristics than soil matrix export, but total soil water flow to tile drains increased more due to preferential flow for stronger sorbing substances. Our results indicate that runoff generation by matrix flow to tile drains gained importance towards the end of the modelling period whereas the contributions from fast surface runoff and preferential flow decreased. Accordingly, TPs were to a large extent exported under different hydrological conditions than their PCs, due to their delayed formation and longer half-lives. Thus, not only their different intrinsic characteristics but also their delayed formation could be responsible for the fact that TPs generally took different pathways than their PCs. We suggest

  9. A field and modeling study of nonlinear storage-discharge dynamics for an Alpine headwater catchment

    NASA Astrophysics Data System (ADS)

    Camporese, Matteo; Penna, Daniele; Borga, Marco; Paniconi, Claudio

    2014-02-01

    A process-based coupled model of surface-subsurface flow is applied to the simulation of nonlinear hydrological dynamics for an experimental mountain headwater catchment in northeastern Italy. The comparison between measured and simulated responses, both distributed (water table and soil moisture) and integrated (streamflow at the outlet), shows that the model satisfactorily reproduces various nonlinear processes, in particular threshold behavior and hysteresis in the catchment storage-discharge relationship. We typically observe a clockwise loop in this relationship, i.e., streamflow response is faster than groundwater and soil moisture response, due to larger time scales for subsurface processes and to soil moisture persistence and redistribution. The model is based on a standard Richards equation representation of integrated saturated-unsaturated-runoff dynamics and needs no ad hoc parameterization (e.g., for macropores, pipe flow, or retention curve hysteresis) to capture observed hysteretic relationships between storage and discharge. Additional numerical experiments are carried out to investigate how heterogeneity (bedrock permeability and the distinction between riparian and hillslope areas) and aquifer thickness and topography affect this nonlinear dynamics. The results show that catchment topography and soil depth exert the main control on the hysteresis and threshold patterns. This is evident from a spatial analysis of streamflow and water table response times to storm events, where the threshold points correspond to changes in terrain slope. These findings are confirmed by a further set of analyses carried out on an idealized v-shaped catchment.

  10. Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments.

    PubMed

    Ockenden, M C; Deasy, C E; Benskin, C McW H; Beven, K J; Burke, S; Collins, A L; Evans, R; Falloon, P D; Forber, K J; Hiscock, K M; Hollaway, M J; Kahana, R; Macleod, C J A; Reaney, S M; Snell, M A; Villamizar, M L; Wearing, C; Withers, P J A; Zhou, J G; Haygarth, P M

    2016-04-01

    We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km(2)) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target

  11. Using long-term data sets to understand transit times in contrasting headwater catchments

    NASA Astrophysics Data System (ADS)

    Hrachowitz, M.; Soulsby, C.; Tetzlaff, D.; Dawson, J. J. C.; Dunn, S. M.; Malcolm, I. A.

    2009-04-01

    SummaryLong-term tracer data collected over an 8 year period were analyzed to explore the transit times of two small (˜1 km 2), contrasting headwater catchments in the uplands of Scotland. At Loch Ard, the catchment was characterized by low permeability gleyed soils overlying metamorphic geology. At Sourhope, more freely draining podzolic soils were dominant, which mantled fractured and faulted volcanic rocks. Hydrometric data and chemically-based hydrograph separations indicated that Loch Ard was a flashy catchment dominated by runoff processes in the upper soil horizons. In contrast, around 77% of annual flow at Sourhope was sustained by well-buffered groundwater sources. Weekly Cl - time series in precipitation and stream flow revealed similar variability in inputs at both sites, but much greater damping in outputs at Sourhope. Despite this, both catchments filtered white noise frequencies in precipitation inputs into 1/ f outputs. These input-output relationships were modeled with a range of transit time distributions (TTD). At the responsive Loch Ard catchment, mean transit times (MTT) for the study period were estimated at 135-202 days. Models based on a gamma distribution or two parallel linear reservoirs were best able to capture the short- and long-term fluctuations in stream water in response to input variations. At Sourhope, the highly damped tracer signal in stream waters was poorly captured by all the TTDs used. Resulting MTT estimates of 1830-1970 days are based on weak model fits and poorly identifiable parameter sets, indicating that natural tracers such as Cl - are inadequate for catchments where MTTs are greater than a few years. At both sites, estimates of MTT using moving windows over the 8 year data sets revealed sensitivity to precipitation amounts and the length of monitoring period. It is concluded that time series of around 4 years are required to adequately constrain MTT estimates.

  12. Characterizing Runoff and Water Yield from Headwater Catchments in the Southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Safeeq, M.; Hunsaker, C. T.

    2015-12-01

    In a mediterranean climate where much of the annual precipitation falls during winter, the snow-capped Sierra Nevada serves as the primary source of dry season runoff that supports agriculture, industries, urban, and other ecosystems. Increased warming has led to significant reductions in mountain snowpack accumulation and earlier snowmelt throughout the western United States where most of the snow accumulates at temperatures near the freezing point. As a result, declines in dry season runoff magnitude, earlier runoff timing, and altered flood risk have been reported across the region. An important question in this context is, how to best manage forested catchments for water and other ecosystem services? We depict the differences in hydrologic response of ten catchments in the Kings River Experimental Watersheds (KREW) research project using continuous precipitation, snow, and runoff data during 2004-2014. The size of these catchments ranges from 50 to 475 ha, and they span a 600-m elevation range in the rain snow transitional zone. In terms of soil, Shaver and Gerle-Cagwin dominate the lower elevation Providence catchments, and Cagwin soils dominate the higher elevation Bull catchments. The majority of these catchments have southwest aspect, moderate average slope (i.e. <25%), and a well-developed drainage network with drainage density ranging from 4.6 to 10.1 km/km2. Bull catchments, on average, have higher runoff than the Providence catchments across all hydrologic signatures extracted from daily hydrographs. Mean annual runoff ranges between 281 to 408 mm in Providence and 436 to 656 mm in Bull catchments despite no significant difference in precipitation among KREW's four meteorological stations. However, high elevation Bull catchments receive significantly more precipitation as snow than the low elevation Providence catchments. The average runoff ratio ranges from 18% to as high as 43% among different catchments, indicating that the catchment

  13. Runoff of small rocky headwater catchments: Field observations and hydrological modeling

    NASA Astrophysics Data System (ADS)

    Gregoretti, C.; Degetto, M.; Bernard, M.; Crucil, G.; Pimazzoni, A.; De Vido, G.; Berti, M.; Simoni, A.; Lanzoni, S.

    2016-10-01

    In dolomitic headwater catchments, intense rainstorms of short duration produce runoff discharges that often trigger debris flows on the scree slopes at the base of rock cliffs. In order to measure these discharges, we placed a measuring facility at the outlet (elevation 1770 m a.s.l.) of a small, rocky headwater catchment (area ˜0.032 km2, average slope ˜320%) located in the Venetian Dolomites (North Eastern Italian Alps). The facility consists of an approximately rectangular basin, ending with a sharp-crested weir. Six runoff events were recorded in the period 2011-2014, providing a unique opportunity for characterizing the hydrological response of the catchment. The measured hydrographs display impulsive shapes, with an abrupt raise up to the peak, followed by a rapidly decreasing tail, until a nearly constant plateau is eventually reached. This behavior can be simulated by means of a distributed hydrological model if the excess rainfall is determined accurately. We show that using the Soil Conservation Service Curve-Number (SCS-CN) method and assuming a constant routing velocity invariably results in an underestimated peak flow and a delayed peak time. A satisfactory prediction of the impulsive hydrograph shape, including peak value and timing, is obtained only by combining the SCS-CN procedure with a simplified version of the Horton equation, and simulating runoff routing along the channel network through a matched diffusivity kinematic wave model. The robustness of the proposed methodology is tested through a comparison between simulated and observed timings of runoff or debris flow occurrence in two neighboring alpine basins.

  14. Prediction of glacier melt and runoff for a high-altitude headwater catchment in Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Liu, T.; Kinouchi, T.; Mendoza, J.; Asaoka, Y.

    2013-12-01

    In Andes, retreat of tropical glaciers is rapid, thus water resources currently available from glacierized catchments would be changed in its volume and temporal variations due to climate change and glacier shrinkage. Water resources in La Paz and El Alto, Bolivia, strongly depend on the runoff from glacierized headwater catchments in the Cordillera Real, Andes, which is a combined contribution from glacier and snow melts in glacierized areas and surface and subsurface runoff due to snowmelt and rainfall in non-glacierized areas. To predict long-term availability of water resources from glacierized catchments in the Cordillera Real, we developed a semi-distributed conceptual glacio-hydrological model applicable for the partially glacierized catchments in high mountains by considering different phases of precipitation, various runoff components from glacierized and non-glacierized areas, the retarding effect by lakes and wetlands, and the change of glacierized areas based on the area-volume relationship. The model was successfully applied to the Huayna West headwater catchment located in the Cordillera Real, Bolivian Andes, for the period of June 2011 to May 2013, after calibrating by observed meteorological and hydrological conditions. Our results indicate that the glacier melt is enhanced during two transition periods, i.e. from the dry to wet season (October to early December) and the wet to dry season (March to May), while the surface runoff from snowmelt and subsurface runoff are more dominant between the two periods from December to February. It was found that the simulated runoff was highly sensible to spatial and temporal variation of air temperature, and smoothed by the subsurface flow and retarding processes in lakes and wetlands. We predicted the change of glacierized area and runoff until 2050 under different climate scenarios, which indicates that the glacier continues to shrink by 2050 resulting in the areal reduction ranging from 65% to 73% and

  15. Effects of bedrock groundwater on landslide occurrences in a steep headwater catchment

    NASA Astrophysics Data System (ADS)

    Kosugi, K.; Fujimoto, M.; Sando, Y.; Mizuyama, T.; Kinoshita, A.

    2011-12-01

    Previous studies have shown that the formation of groundwater in the soil mantle greatly affects slope instability on steep landscapes. To predict landslides, mathematical models based on a geographic information system, which organize geographic data such as information on upslope contributing areas and the local slope gradient, have been developed and tested. Although such models can be used to calculate the topographically driven convergence of rainwater and groundwater table developments in the soil mantle, thus providing a spatially distributed prediction of landslide occurrences, the accuracy of these mathematical models is still limited, mainly because they ignore storm responses in underlying bedrock. Recent research has provided credible information on the importance of bedrock groundwater on surface hydrological processes in headwater catchments. To elucidate the effects of bedrock groundwater, the dynamics of bedrock groundwater should be measured directly. However, intensive monitoring of bedrock groundwater is rare in mountains with steep topography. Consequently, how bedrock groundwater controls landslides in a steep headwater catchment is in dispute. In this study, we conducted long-term hydrological observations using densely nested bedrock wells along with monitoring of discharge hydrograph and soil mantle groundwater in a steep headwater catchment underlain by granitic bedrock. Bedrock wells with depths of 7-78 m were drilled at 31 points within the 2.10-ha catchment. Results showed that a hollow of bedrock aquifer was located at a ridge in the surface topography, clearly indicating bedrock groundwater flow across topographic divides. Around a point where the bedrock groundwater exfiltrated, we found scars of landslides. Such landslides cannot be explained by mathematical hydrology models, which calculate the topographically driven convergence of rainwater in the soil mantle. Moreover, at a point along the main hollow of the watershed, we observed

  16. Relative influence of different habitat factors on creek chub population structure within channelized agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Creek chubs (Semotilus atromaculatus) are commonly found within channelized agricultural headwater streams within the Midwestern United States. Understanding the relationships of this headwater fish species with different habitat factors will provide information that can assist with developing resto...

  17. Differences in instream wood characteristics between channelized and unchannelized agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Instream wood is an important resource for stream biota because it provides cover for fishes, substrate for macroinvertebrates, and increases habitat diversity. However, current management of instream wood within channelized agricultural headwater streams (drainage ditches) involves removing instrea...

  18. The importance of instream habitat modifications for restoring channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Science based information on the influence of restoration practices on fishes within channelized agricultural headwater streams in the Midwestern United States is currently lacking. Understanding fish-habitat relationships and fish responses to specific restoration practices will provide informatio...

  19. DIN retention-transport through four hydrologically connected zones in a headwater catchment of the Upper Mississippi River

    USGS Publications Warehouse

    Triska, F.J.; Duff, J.H.; Sheibley, R.W.; Jackman, A.P.; Avanzino, R.J.

    2007-01-01

    Dissolved inorganic nitrogen (DIN) retention-transport through a headwater catchment was synthesized from studies encompassing four distinct hydrologic zones of the Shingobee River Headwaters near the origin of the Mississippi River. The hydrologic zones included: (1) hillslope ground water (ridge to bankside riparian); (2) alluvial riparian ground water; (3) ground water discharged through subchannel sediments (hyporheic zone); and (4) channel surface water. During subsurface hillslope transport through Zone 1, DIN, primarily nitrate, decreased from ???3 mg-N/l to <0.1 mg-N/l. Ambient seasonal nitrate:chloride ratios in hillslope flow paths indicated both dilution and biotic processing caused nitrate loss. Biologically available organic carbon controlled biotic nitrate retention during hillslope transport. In the alluvial riparian zone (Zone 2) biologically available organic carbon controlled nitrate depletion although processing of both ambient and amended nitrate was faster during the summer than winter. In the hyporheic zone (Zone 3) and stream surface water (Zone 4) DIN retention was primarily controlled by temperature. Perfusion core studies using hyporheic sediment indicated sufficient organic carbon in bed sediments to retain ground water DIN via coupled nitrification-denitrification. Numerical simulations of seasonal hyporheic sediment nitrification-denitrification rates from perfusion cores adequately predicted surface water ammonium but not nitrate when compared to 5 years of monthly field data (1989-93). Mass balance studies in stream surface water indicated proportionally higher summer than winter N retention. Watershed DIN retention was effective during summer under the current land use of intermittently grazed pasture. However, more intensive land use such as row crop agriculture would decrease nitrate retention efficiency and increase loads to surface water. Understanding DIN retention capacity throughout the system, including special channel

  20. Forest management effects on snow, runoff and evapotranspiration in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Ray, R. L.; Saksa, P. C.; Bales, R. C.; Conklin, M. H.

    2012-12-01

    We used intensive field measurements and data-intensive hydro-ecological modeling to investigate the impact of forest vegetation management on the sensitivity of snow accumulation, evapotranspiration and discharge at seven headwater catchments in the Sierra Nevada. Catchments are located in dense mixed-conifer forest, at elevations of 1500 - 2100 m, and receive a mix of rain and snow precipitation. Management scenarios for reducing forest density by uniform thinning and forest clearings were implemented in the Regional Hydro-ecological Simulation System (RHESSys). Results obtained using inherent model equations to separate total precipitation into snow and rain underestimated snow water content in some of the catchments, requiring manual input of snow and rain for accurate simulations. Modeling precipitation phase accurately was critical for the current forest condition, as the change in vegetation has differing effects on rain, snow and snowmelt. Results using RHESSys show that light, uniform thinning alone (<20% canopy) may not be enough to change water yield significantly, but this threshold of canopy reduction is lowered by creating gaps in the forest alone or in combination with uniform thinning, and has potential to measurably increase water yield beyond background variation. Clarifying these specific impacts of forest vegetation on snow processes and water yield is essential for simulating forest management in the Sierra Nevada and it shows the forest structure has significant influence on the catchment water balance. However, modifying forest canopy density and canopy cover to calculate average levels of snow water equivalent at a basin-scale may not be detailed enough to incorporate all the complex forest structure effects on snow processes in mountain watersheds.

  1. Characteristics and controls of variability in soil moisture and groundwater in a headwater catchment

    NASA Astrophysics Data System (ADS)

    McMillan, H. K.; Srinivasan, M. S.

    2015-04-01

    Hydrological processes, including runoff generation, depend on the distribution of water in a catchment, which varies in space and time. This paper presents experimental results from a headwater research catchment in New Zealand, where we made distributed measurements of streamflow, soil moisture and groundwater levels, sampling across a range of aspects, hillslope positions, distances from stream and depths. Our aim was to assess the controls, types and implications of spatial and temporal variability in soil moisture and groundwater tables. We found that temporal variability in soil moisture and water table is strongly controlled by the seasonal cycle in potential evapotranspiration, for both the mean and extremes of their distributions. Groundwater is a larger water storage component than soil moisture, and this general difference increases even more with increasing catchment wetness. The spatial standard deviation of both soil moisture and groundwater is larger in winter than in summer. It peaks during rainfall events due to partial saturation of the catchment, and also rises in spring as different locations dry out at different rates. The most important controls on spatial variability in storage are aspect and distance from the stream. South-facing and near-stream locations have higher water tables and showed soil moisture responses for more events. Typical hydrological models do not explicitly account for aspect, but our results suggest that it is an important factor in hillslope runoff generation. Co-measurement of soil moisture and water table level allowed us to identify relationships between the two. Locations where water tables peaked closer to the surface had consistently wetter soils and higher water tables. These wetter sites were the same across seasons. However, patterns of strong soil moisture responses to summer storms did not correspond to the wetter sites. Total catchment spatial variability is composed of multiple variability sources, and the

  2. Origin of particulate organic matter exported during storm events in a forested headwater catchment.

    NASA Astrophysics Data System (ADS)

    Jeanneau, Laurent; Rowland, Richard D.; Inamdar, Shreeram P.

    2016-04-01

    and river banks decreases while the influence of Forest O horizon increases. For suspended sediments, the evolution during storm events were opposite in the 12ha and the 79ha catchments. In the 12ha catchment, during the rising limb of the hydrograph, POM seems to be inherited from stream bed sediments and river banks, while from the rising limb to the peak flow, the influence of litter and/or wetland increases. This influence decreases during the falling limb. The opposite trend was observed in the 79ha catchment, with an increasing contribution of stream bed sediments to the OM exported during a storm event. What is the information to take away? First POM transferred in headwater catchments has multiple sources. Secondly, the combination of those sources is different along the size continuum of particles. Then, down a continuum of catchment drainage locations, the combination of sources changes both along the size continuum and during storm events. This information is critical for identifying the various drivers and mechanisms behind POM transport and for understanding the impacts of POM on aquatic metabolism and downstream water quality.

  3. Fate and transport of polycyclic aromatic hydrocarbons in upland irish headwater lake catchments.

    PubMed

    Scott, Heidi E M; Aherne, Julian; Metcalfe, Chris D

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are a concern due to their carcinogenicity and propensity for transboundary atmospheric transport. Ireland is located on the western periphery of Europe and assumed to receive clean Atlantic air. As such, it has been used as an atmospheric reference for comparison to other regions. Nonetheless, few studies have evaluated concentrations of PAHs within the Irish environment. In the current study, PAHs were measured at five upland (500-800 masl) headwater lake catchments in coastal regions around Ireland, remote from industrial point source emissions. Semipermeable membrane devices were deployed in lakes for a 6-month period in July 2009, and topsoils were sampled from each catchment during October 2010. The concentrations of PAHs were low at most study sites with respect to other temperate regions. Homologue groups partitioned between lake and soil compartments based on their molecular weight were: "lighter" substances, such as Phenanthrene and Fluorene, were found in higher proportions in lakes, whereas "heavier" compounds, such as Chrysene and Benz[a]anthracene, were more prominent in soils. Concentrations of PAHs were highest at the east coast sites, potentially due to contributions from historical transboundary and regional combustion sources.

  4. Fate and Transport of Polycyclic Aromatic Hydrocarbons in Upland Irish Headwater Lake Catchments

    PubMed Central

    Scott, Heidi E. M.; Aherne, Julian; Metcalfe, Chris D.

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are a concern due to their carcinogenicity and propensity for transboundary atmospheric transport. Ireland is located on the western periphery of Europe and assumed to receive clean Atlantic air. As such, it has been used as an atmospheric reference for comparison to other regions. Nonetheless, few studies have evaluated concentrations of PAHs within the Irish environment. In the current study, PAHs were measured at five upland (500–800 masl) headwater lake catchments in coastal regions around Ireland, remote from industrial point source emissions. Semipermeable membrane devices were deployed in lakes for a 6-month period in July 2009, and topsoils were sampled from each catchment during October 2010. The concentrations of PAHs were low at most study sites with respect to other temperate regions. Homologue groups partitioned between lake and soil compartments based on their molecular weight were: “lighter” substances, such as Phenanthrene and Fluorene, were found in higher proportions in lakes, whereas “heavier” compounds, such as Chrysene and Benz[a]anthracene, were more prominent in soils. Concentrations of PAHs were highest at the east coast sites, potentially due to contributions from historical transboundary and regional combustion sources. PMID:23346024

  5. Model‐based analysis of the influence of catchment properties on hydrologic partitioning across five mountain headwater subcatchments

    PubMed Central

    Wagener, Thorsten; McGlynn, Brian

    2015-01-01

    Abstract Ungauged headwater basins are an abundant part of the river network, but dominant influences on headwater hydrologic response remain difficult to predict. To address this gap, we investigated the ability of a physically based watershed model (the Distributed Hydrology‐Soil‐Vegetation Model) to represent controls on metrics of hydrologic partitioning across five adjacent headwater subcatchments. The five study subcatchments, located in Tenderfoot Creek Experimental Forest in central Montana, have similar climate but variable topography and vegetation distribution. This facilitated a comparative hydrology approach to interpret how parameters that influence partitioning, detected via global sensitivity analysis, differ across catchments. Model parameters were constrained a priori using existing regional information and expert knowledge. Influential parameters were compared to perceptions of catchment functioning and its variability across subcatchments. Despite between‐catchment differences in topography and vegetation, hydrologic partitioning across all metrics and all subcatchments was sensitive to a similar subset of snow, vegetation, and soil parameters. Results also highlighted one subcatchment with low certainty in parameter sensitivity, indicating that the model poorly represented some complexities in this subcatchment likely because an important process is missing or poorly characterized in the mechanistic model. For use in other basins, this method can assess parameter sensitivities as a function of the specific ungauged system to which it is applied. Overall, this approach can be employed to identify dominant modeled controls on catchment response and their agreement with system understanding. PMID:27642197

  6. Comparing runoff on 11 poorly-gauged headwater catchments using a soft monitoring approach

    NASA Astrophysics Data System (ADS)

    Colin, F.; Crabit, A.; Moussa, R.

    2012-04-01

    Catchments in many parts of the world are either ungauged or poorly gauged, and the dominant processes governing their streamflow response are still poorly understood. The analysis of runoff coefficients provides essential insight into catchment response, particularly if both range of catchments and a range of events are compared. An original soft water level sensor is proposed to characterize rainfall and stream flows on agricultural catchments. This sensor works as a capacitor coupled with a capacitance to frequency converter and measures water level at an adjustable time step acquisition. It was designed to be handy, minimally invasive and optimised in terms of energy consumption and low-cost fabrication so as to multiply its use on several catchments under natural conditions. It was used as a stage recorder to measure water level dynamics in a channel during a runoff event and as a rain gauge to measure rainfall amount and intensity. Innovative work has been performed under controlled experimental conditions to estimate Manning's coefficient values for the different cover types observed in studied streams: non-aquatic vegetations (giant reed, bramble and thistle), grass and coarse granular deposits. The results show that estimates derived using roughness coefficients differ from those previously established for larger streams with aquatic vegetation. Based on these results, water discharge with a given uncertainty and hence runoff volume were estimated at the event and the annual scale. The sensor was tested under controlled conditions in the laboratory and under real conditions in the field. Comparisons of the sensor to reference devices (tipping bucket rain gauge, hydrostatic pressure transmitter limnimeter, Venturi channels, ...) showed accurate results: rainfall intensities and dynamic responses were accurately reproduced and discharges were estimated with an uncertainty usually acceptable in hydrology (Crabit et al., in Sensors 11, 2011). This device were

  7. Riparian zone flowpath dynamics during snowmelt in a small headwater catchment

    USGS Publications Warehouse

    McGlynn, B.L.; McDonnell, Jeffery J.; Shanley, J.B.; Kendall, C.

    1999-01-01

    The hydrology of the near-stream riparian zone in upland humid catchments is poorly understood. We examined the spatial and temporal aspects of riparian flowpaths during snowmelt in a headwater catchment within the Sleepers River catchment in northern Vermont. A transect of 15 piezometers was sampled for Ca, Si, DOC, other major cations, and ??18O. Daily piezometric head values reflected variations in the stream hydrograph induced by melt and rainfall. The riparian zone exhibited strong upward discharge gradients. An impeding layer was identified between the till and surficial organic soil. Water solute concentrations increased toward the stream throughout the melt. Ca concentrations increased with depth and DOC concentrations decreased with depth. The concentrations of Ca in all piezometers were lower during active snowmelt than during post-melt low flow. Ca data suggest snowmelt infiltration to depth; however, only upslope piezometers exhibited snowmelt infiltration and consequent low ??18O values, while ??18O values varied less than 0.5% in the deep riparian piezometers throughout the study period. Ca and ??18O values in upslope piezometers during low streamflow were comparable to Ca and ??18O in riparian piezometers during high streamflow. The upland water Ca and ??18O may explain the deep riparian Ca dilution and consistent ??18O composition. The temporal pattern in Ca and ??18O indicate that upland water moves to the stream via a lateral displacement mechanism that is enhanced by the presence of distinct soil/textural layers. Snowmelt thus initiates the flux of pre-melt, low Ca upland water to depth in the riparian zone, but itself does not appear at depth in the riparian zone during spring melt. This is despite the coincident response of upland groundwater and stream discharge.The hydrology of the near-stream riparian zone in upland humid catchments is poorly understood. We examined the spatial and temporal aspects of riparian flowpaths during snowmelt in a

  8. Headwater sediment dynamics in a debris flow catchment constrained by high-resolution topographic surveys

    NASA Astrophysics Data System (ADS)

    Loye, Alexandre; Jaboyedoff, Michel; Theule, Joshua Isaac; Liébault, Frédéric

    2016-06-01

    Debris flows have been recognized to be linked to the amounts of material temporarily stored in torrent channels. Hence, sediment supply and storage changes from low-order channels of the Manival catchment, a small tributary valley with an active torrent system located exclusively in sedimentary rocks of the Chartreuse Massif (French Alps), were surveyed periodically for 16 months using terrestrial laser scanning (TLS) to study the coupling between sediment dynamics and torrent responses in terms of debris flow events, which occurred twice during the monitoring period. Sediment transfer in the main torrent was monitored with cross-section surveys. Sediment budgets were generated seasonally using sequential TLS data differencing and morphological extrapolations. Debris production depends strongly on rockfall occurring during the winter-early spring season, following a power law distribution for volumes of rockfall events above 0.1 m3, while hillslope sediment reworking dominates debris recharge in spring and autumn, which shows effective hillslope-channel coupling. The occurrence of both debris flow events that occurred during the monitoring was linked to recharge from previous debris pulses coming from the hillside and from bedload transfer. Headwater debris sources display an ambiguous behaviour in sediment transfer: low geomorphic activity occurred in the production zone, despite rainstorms inducing debris flows in the torrent; still, a general reactivation of sediment transport in headwater channels was observed in autumn without new debris supply, suggesting that the stored debris was not exhausted. The seasonal cycle of sediment yield seems to depend not only on debris supply and runoff (flow capacity) but also on geomorphic conditions that destabilize remnant debris stocks. This study shows that monitoring the changes within a torrent's in-channel storage and its debris supply can improve knowledge on recharge thresholds leading to debris flow.

  9. Active Stream Length Dynamics in Headwater Catchments Spanning Physiographic Provinces in the Appalachian Highlands

    NASA Astrophysics Data System (ADS)

    Jensen, C.; McGuire, K. J.

    2015-12-01

    One of the most basic descriptions of streams is the presence of channelized flow. However, this seemingly simple query goes unanswered for the majority of headwater networks, as stream length expands and contracts with the wetness of catchments seasonally, interannually, and in response to storm events. Although streams are known to grow and shrink, a lack of information on longitudinal dynamics across different geographic regions precludes effective management. Understanding the temporal variation in temporary network length over a broad range of settings is critical for policy decisions that impact aquatic ecosystem health. This project characterizes changes in active stream length for forested headwater catchments spanning four physiographic provinces of the Appalachian Highlands: the New England at Hubbard Brook Experimental Forest, New Hampshire; Valley and Ridge at Poverty Creek and the North Fork of Big Stony Creek in Jefferson National Forest, Virginia; Blue Ridge at Coweeta Hydrologic Laboratory, North Carolina; and Appalachian Plateau at Fernow Experimental Forest, West Virginia. Multivariate statistical analysis confirms these provinces exhibit characteristic topographies reflecting differences in climate, geology, and environmental history and, thus, merit separate consideration. The active streams of three watersheds (<45 ha) in each study area were mapped six times to capture a variety of moderate flow conditions that can be expected most of the time (i.e., exceedance probabilities between 25 to 75%). The geomorphic channel and channel heads were additionally mapped to determine how active stream length variability relates to the development of the geomorphic network. We found that drainage density can vary up to four-fold with discharge. Stream contraction primarily proceeds by increasing disconnection and disintegration into pools, while the number of flow origins remains constant except at high and low extremes of discharge. This work demonstrates

  10. Linking Soil Moisture, Micro-climate, and Transpiration in a Headwater Catchment

    NASA Astrophysics Data System (ADS)

    Barnard, H. R.; Brooks, J.; Kayler, Z.; Sulzman, E. W.; Phillips, C. L.; McDonnell, J. J.; Bond, B. J.

    2007-12-01

    Evapotranspiration is a major determinant of streamflow in forested basins. However, the role topography plays in forest water relations is poorly understood. To date, many hydrological models use only a single value for transpiration across a catchment. Quantifying the variation in forest water use with regards to slope position is central to understanding controls on water quantity and quality in hydro-ecological models and is critical to predicting the hydrologic impacts of various forestry operations. We measured transpiration, soil moisture, and foliar pre-dawn water potential in 4 plots across a ridge to ridge transect throughout the summers of 2005 and 2006 in a headwater catchment in western Oregon. Additionally, we measured deuterium and 18O of xylem water and soil water to track changes in the depth of transpiration source water throughout the summers. From May through October 2006, daily average transpiration in upslope plots was approximately 40% greater than that of valley bottom plots (1.0 mm day-1 vs. 0.6 mm day-1, respectively). Minimum pre-dawn water potential values ranged from -0.8 to -1.3 MPA in late August with north-facing plots having the lowest values. Stable isotope data indicates that transpiration rates remained higher longer in the growing season in plots where trees were able to access water deeper in the soil profile. Preliminary data suggest that topographic gradients influencing soil depth, soil moisture retention, and micro-climate result in large variation in forest water use over very small distances.

  11. Nitrate removal and denitrification in headwater agricultural streams of the Pacific Northwest

    EPA Science Inventory

    Headwater streams can serve as important sites for nitrogen (N) removal in watersheds. Here we examine the influence of agricultural streams on watershed N export in the Willamette River Basin of western Oregon, USA, a region with mixed agricultural, urban and forestry land uses...

  12. Dissolved Carbon Flux and Mass Balance From a Wetland-Dominated Karstic Headwater Catchment

    NASA Astrophysics Data System (ADS)

    Duval, T. P.; Waddington, J. M.; Branfireun, B. A.

    2009-05-01

    The stream-borne dissolved carbon efflux of peatland-draining catchments is dominated by organic carbon, whereas inorganic carbon dominates the flux from calcareous bedrock catchments. The export of dissolved carbon from calcareous bedrock catchments with significant wetland coverage has not previously been determined. This study documents the spatiotemporal variability of dissolved carbon (inorganic + organic) along a headwater stream in southern Ontario, Canada, as it drains three distinct wetland types: a calcareous fen, a riparian cedar swamp, and a cattail marsh. Upon emergence from the groundwater seeps, the spring water contained 28 times more CO2 than in equilibrium with the atmosphere. This supersaturation decreased to just 5 times equilbrium as the stream leaves the catchment through the marsh, representing a decrease in CO2 concentration of 11 mg L-1, lost to the atmosphere as exsolution. The groundwater seeps contained an average of 1.25±0.75 mg L-1 of dissolved organic carbon (DOC) from May to November 2007, one of the driest years on record in the region. At the catchment outlet through the marsh, DOC concentrations were slightly higher and more variable during the same period at 2.27±1.29 mg L-1, as a fall flushing event resulted in concentrations > 7 mg L-1. This DOC concentration is small compared to the 58.72±3.9 mg L-1 of dissolved inorganic carbon (DIC, as bicarbonate ion) contained within the water leaving the catchment. At 0.21 and 0.17 g m-2 d-1 from May-July and August-November 2007, respectively, the DIC dominated the carbon flux out of the watershed, compared with 0.007 and 0.008 g m- 2 d-1 DOC and 0.015 and 0.009 g m-2 d-1 CO2 exsolution during the same period. Results of the 2007 season will be contrasted to the 2008 season, one of the wettest on record. The watershed is underlain by Silurian dolomite that exhibits karst fractures, resulting in a complex subsurface hydrogeology that influences carbon transport and mass balances

  13. Geomorphic (de-) coupling of hillslope and channel systems within headwater catchments in two subarctic tributary valleys, Nordfjord, Western Norway

    NASA Astrophysics Data System (ADS)

    Laute, Katja; Beylich, Achim A.

    2010-05-01

    Hillslopes occupy large areas of the earth surface. Studying the characteristics, development and interaction of hillslopes as components of the geomorphic hillslope-channel coupling process-response system will improve the understanding of the complex response of mountain landscape formation. The rates of hillslope processes are exceptionally varied and affected by many influences of varying intensity. Hillslope-channel coupling and sediment storage within slopes are important factors that influence sediment delivery through catchments, especially in steep environments. Within sediment transfers from sources to sinks in drainage basins, hillslopes function as a key element concerning sediment storage, both for short term periods as between rainstorms as well as for longer periods in colluvial deposits. This PhD project is part of the NFR funded SedyMONT-Norway project within the ESF TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) programme. The focus of this study is on geomorphic hillslope-channel coupling or de-coupling and sediment transport within four distinct headwater areas of the Erdalen and Bødalen catchments in the Nordfjord valley-fjord system (inner Nordfjord, Western Norway). Both catchments can be described as steep, U-shaped and glacier-fed, subarctic tributary valleys. Approximately 14% of the 49 km2 large headwater area of Erdalen is occupied by hillslope deposits; in Bødalen hillslope deposits occupy 12% of the 42 km2 large headwater area. The main aims of the study are to present preliminary findings on (i) the identification of possible sediment sources and delivery pathways within the headwater areas of the catchments, (ii) to analyze the development of hillslope-channel coupling / de-coupling from postglacial to contemporary timescales as well as (iii) to investigate the current degree of geomorphic hillslope-channel coupling within the different headwater catchments and (iv) to

  14. Hydrological modelling of an artificial headwater catchment using the model system WaSiM-ETH

    NASA Astrophysics Data System (ADS)

    Hölzel, H.; Diekkrüger, B.

    2009-04-01

    The hydrological headwater catchment Chicken Creek (6.5 ha) was constructed in a lignite open-cast mine by Cottbus (Germany) to study initial processes of ecosystem development. The catchment has been intensively monitored for more than three years. Thereby, it is well suited to test and develop hydrological models. The construction of a clay layer in the basement simplifies the balancing of the water cycle since lateral inflows and vertical outflows can be neglected. For modelling purposes all basic input data were given, but neither discharge nor soil moisture measurements were provided. Hence, no high model quality can be feigned by fitting simulated results on observed output data. To compare the ability of different models and modellers to describe the hydrological behaviour of that catchment, a model competition was declared, on which several international scientists take part, all specialised in hydrological modelling. The contest is conducted in different levels, whereupon the knowledge of modellers concerning the investigated catchment will be increased stepwise. All modellers use the same database and results will be evaluated by an independent observer group. Thereby, the comparability between different model applications is guaranteed. We applied the process-based distributed Water balance Simulation Model (WaSiM-ETH) by Schulla & Jasper (2007) to simulate the first three years since the catchment construction was finished (Sep. 2005 - Aug. 2008). For the first modelling exercise important initial conditions (e.g. soil moisture) were unknown. Due to the lack of field experiences, effects of a constructed lake were disregarded. Therefore, the results of the first level were far away from being perfect, e.g. discharge was simulated from the beginning which was not observed because in reality soil water and lake storages were filled up first. The biggest differences occurred between simulated and observed surface runoff. In reality, surface runoff is the

  15. Radioactive Cs-137 discharge from Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    NASA Astrophysics Data System (ADS)

    Iwagami, S.; Onda, Y.; Tsujimura, M.; Sakakibara, K.; Konuma, R.

    2015-12-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, Cs-137 concentration of dissolved water, suspended sediment and coarse organic matter such as leaf and branch were monitored. Discharge amount of stream water, suspended sediment and coarse organic matter were measured to investigate the discharge amount of radiocesium and composition of radiocesium discharge form through the headwater stream. Observation were conducted at stream site in four headwater catchments in Yamakiya district, located ~35 km north west of FDNPP from June 2011 (suspended sediment and coarse organic matter: August 2012) to December 2014.The Cs-137 concentration of dissolved water was around 1Bq/l at June 2011. Then declined to 0.1 Bq/l at December 2011. And in December 2014, it declined to 0.01 Bq/l order. Declining trend of Cs-137 concentration in dissolved water was expressed in double exponential model. Also temporary increase was observed in dissolved Cs-137 during the rainfall event. The Cs-137 concentration of suspended sediment and coarse organic matter were 170-49000 Bq/kg and 350-14000 Bq/kg respectably. The Cs-137 concentration of suspended sediment showed good correlation with average deposition density of catchment. The effect of decontamination works appeared in declining of Cs-137 concentration in suspended sediment. Contribution rate of Cs-137 discharge by suspended sediment was 96-99% during a year. Total annual Cs-137 discharge from the catchment were 0.02-0.3% of the deposition.

  16. Understanding drivers of the export of dissolved organic carbon from headwater catchments in Germany using Generalised Additive Models

    NASA Astrophysics Data System (ADS)

    Selle, Benny; Tittel, Jörg; Musolff, Andreas

    2015-04-01

    In the literature, several causes of recently increasing concentrations of dissolved organic carbon (DOC) in headwaters across eastern North America and northern and central Europe have been debated. One likely driver of the widespread increase of DOC concentrations since the early to mid 1990s are decreasing depositions of acid rain resulting in an increased solubility of organic carbon compounds including humic acids. Here, we tested the hypothesis if the reduced availability of both nitrate and sulfate stimulated the reduction of ferric iron soil minerals and the mobilisation of DOC. Decreasing depositions often resulted in a reduced availability of both nitrate and sulphate, which are preferred electron acceptors in microbial decomposition processes. As iron minerals act as efficient sorbents of organic compounds in soils its reduction may have caused a release of humic substances and hence an increasing export of DOC from headwater catchments. To test this hypothesis, time series of DOC, dissolved iron, sulfate and nitrate from several German headwater catchments were examined using Generalised Additive Models. Using this modelling technique, discharge corrected time series of concentrations were represented as a sum of a seasonal and a non-linear trend component. Both, the computed trends and seasonalities supported the redox hypothesis.

  17. Hydrologic Connectivity in Headwater Catchments Underlain by Continuous Permafrost: Hydrological, Thermal and Biogeochemical Patterns

    NASA Astrophysics Data System (ADS)

    Godsey, S.; Rushlow, C. R.; Harms, T.

    2014-12-01

    Hydrologic connectivity within headwater fluvial networks depends largely on subsurface patterns of moisture. Dynamic subsurface properties that control those patterns can vary widely and are poorly constrained in many systems. However, subsurface conditions change seasonally in a predictable way in catchments underlain by permafrost due to increasing thaw throughout the summer season, and those changes can be systematically measured. Zero-order linear flow features known as water tracks are found in upland permafrost hillslopes and occupy up to 35% of the landscape. Water tracks often connect to downstream fluvial systems via subsurface pathways, but those connections are poorly understood. We present data from six water tracks underlain by permafrost in northern Alaska. We improve our understanding of water tracks and their connections to downstream fluvial systems in two ways. First, we compare the fraction of snow and rain comprising flows in water tracks and the downstream systems to which they connect, and we discuss the resulting constraints on biogeochemical fluxes in these systems. Second, we examine the subsurface controls on water track connectivity patterns by characterizing the water tracks' thermal signatures. We demonstrate that a shallow unfrozen layer permits subsurface flow to continue below a surface frozen layer for up to 6 months after air temperatures drop below freezing, enhancing fall and winter water track downstream connectivity. Because winter air temperatures are projected to increase and become more variable, we examine the role of freeze-thaw events on hydrologic connectivity: some water tracks are less responsive to rapid air temperature changes than surrounding hillslopes. At these sites, soils inside the water tracks remain frozen and impermeable for ~10 more days each year and cycle through fewer freeze-thaw cycles than the same soils outside water tracks. Some shallow soils outside some water tracks freeze and thaw up to 3-fold

  18. Freshwater transport forms of Na, Mg, and Ca in streams of adjacent headwater catchments composed of differing vegetation

    NASA Astrophysics Data System (ADS)

    Terajima, T.; Moriizumi, M.

    2012-04-01

    To understand the freshwater transport forms of major metals, concentrations of Na, Mg, Ca, Si, and fulvic acid-like materials (FAM) were measured in streams of headwater catchments with differing vegetation (coniferous and deciduous forests). The proportion of non-ionic forms (NIF) relative to total elements in the coniferous and deciduous catchments ranged from 0% to 40% and from 0% to 70%, respectively, in baseflows, and from 5% to 60% and from 20% to 60%, respectively, in stormflows. In the baseflows, NIF and total Si (T-Si) were highly correlated (r > 0.9) in both catchments. In contrast, in the stormflows, T-Si and FAM showed a good correlation (r > 0.8) in both catchments, implying that stormflow may have enhanced organic-inorganic binding. However, in the coniferous catchment, good correlations (r > 0.8) between NIF and T-Si or FAM were associated with only the rising limb of the hydrograph, whereas in the deciduous catchment, good correlations (r > 0.8) were associated with both the rising and falling limbs. These results indicate that: (1) under low-flow conditions, major metals may form binding with clay minerals and thus be transported as NIF, (2) storm events may enhance the binding of clay minerals with humic substances, (3) in the coniferous catchment, the complexation of NIF with the organic-inorganic binding and their transport in stormflows are associated with the rising limb of the storm hydrograph, whereas NIF transport during the falling limb may reflect the effect of other materials, and (4) in the deciduous catchment, NIF transport may occur mainly in association with organic-inorganic binding throughout a storm event. These findings show that active binding of Na, Mg, and Ca in freshwater environments with organic and inorganic substances, under the effect of differing vegetation on that binding, should be carefully examined in studies of chemical hydrology in headwater catchments. Key words: fulvic acid, major metal, complexation, humic

  19. Flushing of distal hillslopes as an alternative source of stream dissolved organic carbon in a headwater catchment

    USGS Publications Warehouse

    Gannon, John P; Bailey, Scott W.; McGuire, Kevin J.; Shanley, James B.

    2015-01-01

    We investigated potential source areas of dissolved organic carbon (DOC) in headwater streams by examining DOC concentrations in lysimeter, shallow well, and stream water samples from a reference catchment at the Hubbard Brook Experimental Forest. These observations were then compared to high-frequency temporal variations in fluorescent dissolved organic matter (FDOM) at the catchment outlet and the predicted spatial extent of shallow groundwater in soils throughout the catchment. While near-stream soils are generally considered a DOC source in forested catchments, DOC concentrations in near-stream groundwater were low (mean = 2.4 mg/L, standard error = 0.6 mg/L), less than hillslope groundwater farther from the channel (mean = 5.7 mg/L, standard error = 0.4 mg/L). Furthermore, water tables in near-stream soils did not rise into the carbon-rich upper B or O horizons even during events. In contrast, soils below bedrock outcrops near channel heads where lateral soil formation processes dominate had much higher DOC concentrations. Soils immediately downslope of bedrock areas had thick eluvial horizons indicative of leaching of organic materials, Fe, and Al and had similarly high DOC concentrations in groundwater (mean = 14.5 mg/L, standard error = 0.8 mg/L). Flow from bedrock outcrops partially covered by organic soil horizons produced the highest groundwater DOC concentrations (mean = 20.0 mg/L, standard error = 4.6 mg/L) measured in the catchment. Correspondingly, stream water in channel heads sourced in part by shallow soils and bedrock outcrops had the highest stream DOC concentrations measured in the catchment. Variation in FDOM concentrations at the catchment outlet followed water table fluctuations in shallow to bedrock soils near channel heads. We show that shallow hillslope soils receiving runoff from organic matter-covered bedrock outcrops may be a major source of DOC in headwater catchments in forested mountainous regions

  20. Linking nitrogen management, seep chemistry, and stream water quality in two agricultural headwater watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian seepage zones in headwater agricultural watersheds represent important sources of nitrate-nitrogen (NO3-N) to surface waters, often connecting N-rich groundwater systems to streams. In this study, we examined how NO3-N concentrations in seep and stream water were affected by NO3-N processin...

  1. Controls on denitrification in riparian soils in headwater catchments of a hardwood forest in the Catskill Mountains, U.S.A.

    USGS Publications Warehouse

    Ashby, J.A.; Bowden, W.B.; Murdoch, Peter S.

    1998-01-01

    Denitrification in riparian soils is thought to be an important factor that reduces hydrologic export of nitrate from forested and agricultural catchments. A 2-y study to identify the soil factors most closely associated with denitrification in riparian soils in headwater catchments within the Catskill Mountains of New York, included field surveys of surface and subsurface denitrification rates, and an amendment experiment to assess the relative effects of increases in available carbon and substrate NO-/3 on denitrification rates. Denitrification rates were measured by acetylene inhibition during incubation of intact soil cores from eight soil types representing a range of drainage classes. Soil cores were analyzed for organic matter, total P, extractable NO-/3-N and NH+/4-N, organic N, pH, moisture, porosity, and water-filled pore space, to determine which of these factors were most closely associated with denitrification. The distribution of denitrification rates found during the field surveys was highly skewed, with many low or zero values and few high values. Denitrification rates were positively associated with high soil organic matter, total P, and water-filled pore space, and were highest in seep (poorly-drained) soils, toeslope (seasonally-drained) soils, and stream-edge (poorly- to moderately well-drained) soils in which these three soil characteristics were typically high. Denitrification rates in these wet locations were also positively associated with soil NH+/4-N concentration and pH, but not with NO-/3-N concentration, suggesting that the rate of NO-/3 supply (via nitrification or hydrologic transport) was more important than the instantaneous concentration of NO-/3-N in the soils. The amendment experiment indicated that denitrification in soil types studied was most responsive to added glucose alone or with NO-/3. Thus, in these soils, a combination of slow rates of NO-/3 supply and low available carbon appears to limit denitrification. Annual

  2. Using artificial fluorescent particles as tracers of livestock wastes within an agricultural catchment.

    PubMed

    Granger, Steve J; Bol, Roland; Hawkins, Jane M B; White, Sue M; Naden, Pamela S; Old, Gareth H; Marsh, Jon K; Bilotta, Gary S; Brazier, Richard E; Macleod, Christopher J A; Haygarth, Philip M

    2011-02-15

    Evidence for the movement of agricultural slurry and associated pollutants into surface waters is often anecdotal, particularly with relation to its 'particulate' components which receive less attention than 'bio-available' soluble phases. To assess the extent of movement of slurry particles artificial fluorescent particles were mixed with slurry and applied to a field sub-catchment within a headwater catchment. Particles were 2-60 μm in diameter and two different densities, 2.7 and 1.2 g cm(-3) representing 'inorganic' and 'organic' material. Water samples from the field and catchment outlet were collected during two storm events following slurry application and analysed for particle and suspended sediment concentrations (SSC). SSC from the field and catchment outlet always formed clockwise hysteresis loops indicating sediment exhaustion and particles of the two densities were always found to be positively correlated. Particles from the field formed clockwise hysteresis loops during the first discharge event after slurry application, but anti-clockwise hysteresis loops during the second monitored event which indicated a depletion of readily mobilisable particles. Particles from the catchment outlet always formed anticlockwise hysteresis loops. Particle size became finer spatially, between field and catchment outlet, and temporally, between successive storm events. The results indicate that slurry particles may be readily transported within catchments but that different areas may contribute to pollutant loads long after the main peak in SSC has passed. The density of the particles did not appear to have any effect on particle transport however the size of the particles may play a more important role in the 2-60 μm range.

  3. Post-Wildfire Impacts on Snow Accumulation and Melt: Hydrologic Implications for Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Gleason, K. E.; Nolin, A. W.; Roth, T. R.

    2012-12-01

    disappeared several weeks earlier than in the unburned forest, mainly due to the substantial decrease in snow albedo. We discuss the hydrologic implications for headwater catchments in the West.

  4. Grey water on three agricultural catchments in the Czech Republic

    NASA Astrophysics Data System (ADS)

    Blazkova, Sarka D.; Kulasova, Alena

    2014-05-01

    The COST project EU EURO-AGRIWAT focuses apart from other problems on the assessment of water footprint (WF). WF is defined as the quantity of water used to produce some goods or a service. In particular, the WF of an agricultural product is the volume of water used during the crop growing period. It has three components: the green water which is rain or soil moisture transpired by a crop, the blue water which is the amount of irrigation water transpired and the grey water which is the volume of water required to dilute pollutants and to restore the quality standards of the water body. We have been observing three different agricultural catchments. The first of them is Smrzovka Brook, located in the protected nature area in the south part of the Jizerske Mountains. An ecological farming has been carried out there. The second agricultural catchment area is the Kralovsky Creek, which lies in the foothills of the Krkonose Mountains and is a part of an agricultural cooperative. The last agricultural catchment is the Klejnarka stream, located on the outskirts of the fertile Elbe lowlands near Caslav. Catchments Kralovsky Brook and Klejnarka carry out usual agricultural activities. On all three catchments, however, recreational cottages or houses not connected to the sewerage system and/or with inefficient septic tanks occur. The contribution shows our approach to trying to quantify the real grey water from agriculture, i.e. the grey water caused by nutrients not utilised by the crops.

  5. Water quality status and trends in agriculture-dominated headwaters; a national monitoring network for assessing the effectiveness of national and European manure legislation in The Netherlands.

    PubMed

    Rozemeijer, J C; Klein, J; Broers, H P; van Tol-Leenders, T P; van der Grift, B

    2014-12-01

    Large nutrient losses to groundwater and surface waters are a major drawback of the highly productive agricultural sector in The Netherlands. The resulting high nutrient concentrations in water resources threaten their ecological, industrial, and recreational functions. To mitigate eutrophication problems, legislation on nutrient application in agriculture was enforced in 1986 in The Netherlands. The objective of this study was to evaluate this manure policy by assessing the water quality status and trends in agriculture-dominated headwaters. We used datasets from 5 agricultural test catchments and from 167 existing monitoring locations in agricultural headwaters. Trend analysis for these locations showed a fast reduction of nutrient concentrations after the enforcement of the manure legislation (median slopes of -0.55 mg/l per decade for total nitrogen (N-tot) and -0.020 mg/l per decade for total phosphorus (P-tot)). Still, up to 76 % of the selected locations currently do not comply with either the environmental quality standards (EQSs) for nitrogen (N-tot) or phosphorus (P-tot). This indicates that further improvement of agricultural water quality is needed. We observed that weather-related variations in nutrient concentrations strongly influence the compliance testing results, both for individual locations and for the aggregated results at the national scale. Another important finding is that testing compliance for nutrients based on summer average concentrations may underestimate the agricultural impact on ecosystem health. The focus on summer concentrations does not account for the environmental impact of high winter loads from agricultural headwaters towards downstream water bodies.

  6. The Impact of Enhanced Summer Thaw, Hillslope Disturbances, and Late Season Rainfall on Solute Fluxes from High Arctic Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Lafreniere, M. J.; Lamoureux, S. F.

    2011-12-01

    This study examines variations in the composition and total seasonal fluxes of dissolved solutes in several small High Arctic headwater catchments at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Nunavut (74°54'N, 109°35'W) over multiple snowmelt seasons (2007, 2008, 2009) with contrasting climate and permafrost active layer conditions. Climate warming in the High Arctic will affect a number processes that will alter the hydrological and biogeochemical exports from the landscape. Climate change is projected to alter precipitation regimes, resulting in increases in both winter and summer precipitation in the High Arctic, thereby altering hydrological regimes. Warming will result in thickening of the seasonal active layer, which will alter hydrological flow paths and water and solute sources. Additionally, active layer thickening and permafrost warming is also project to enhance the development of thermokarst features, including hillslope disturbances, such as active layer detachment slides and retrogressive thaw slumps. This research compares the flux of inorganic and organic solutes emanating from a group of catchments that were subject to a range hillslope disturbances, or active layer detachment slides (ALDs), at the end of summer 2007. One of the catchments, Goose, was not subject to any disturbance, while active layer slides covered between 6% and 46% of the catchment area in the disturbed catchments. It was hypothesised that solute fluxes would increase primarily with increasing extent and degree of disturbance. This however, was not observed. Rather, comparing five sites with varying degrees of disturbance in 2009 illustrates that on a specific area and specific volume of runoff basis, solute fluxes were unrelated to disturbance extent. Comparing two catchments that were monitored from 2007 (pre-disturbance) through to 2009 (2 yrs post disturbance), shows that both catchments were subject to solute flux increases, however the solute

  7. Headwater thermal response to partial-retention forest harvesting: a process-based paired-catchment experiment

    NASA Astrophysics Data System (ADS)

    Moore, R. D.; Guenther, S. M.; Gomi, T.

    2008-12-01

    Paired-catchment experiments are the most rigorous empirical research design for estimating the effects of land use on aquatic systems. However, they have recently come under increasing criticism, in part because past studies typically treated catchments as black boxes. As a result, investigators could only speculate about the factors responsible for any observed effects, limiting their ability to generalize the experimental results in space and time. This study used a paired-catchment approach to investigate the effects of partial- retention forest harvesting with no riparian buffer on the thermal regime of a headwater stream in coastal British Columbia. In addition to monitoring stream temperature at three locations within the treatment reach, we monitored above-stream microclimate, water surface evaporation, bed temperature profiles, groundwater temperature, and reach-scale surface-subsurface interaction. Daily maximum stream temperatures increased after harvesting by over 5 °C during summer, with little effect in winter. The major driver of post- harvest warming was an increase in solar radiation, which was partially moderated by the increased effects of hyporheic exchange, bed heat conduction and evaporation. Incorporating process-based measurements into paired-catchment experiments not only allows the causes of treatment response to be assessed, but they provide a valuable data set for testing predictive models.

  8. Melt Energetics of 25-years of Distributed, Physically Based Snowcover Simulations in a Small Headwater Semiarid Mountain Catchment (Invited)

    NASA Astrophysics Data System (ADS)

    Reba, M. L.; Marks, D. G.; Winstral, A. H.; Kumar, M.

    2013-12-01

    Water in the western US is over-allocated due to both urban and rural demands. Over the last 20-30 years climate warming in western North America has resulted in a critical shift in patterns of snow deposition and melt. A carefully collected, processed, and validated meteorological dataset for the 1984 - 2008 water years was assembled for a headwater catchment within the Reynolds Creek Experimental Watershed in the Owyhee Mountains of Idaho. Data from this catchment are representative of conditions across a large region of the interior western US. These data are used to simulate patterns of snow deposition and melt over the catchment for the 25-year period. The simulation period includes both the wettest (1984) and driest (1992) water years, along with a high degree of inter-annual variability. Energetics of six landcover zones and the average within the catchment are compared. Two of these zones are characterized by wind exposure (drift, scour), and four others by general vegetation cover vegetation (fir/conifer, aspen/willow, big sage, mid-sage). Energetics are compared and analyzed to understand how site characteristics moderate the climatic and atmospheric conditions, which control the establishment, development and ablation of the seasonal snowcover.

  9. Hydro-climatic control of stream dissolved organic carbon in headwater catchment

    NASA Astrophysics Data System (ADS)

    Humbert, Guillaume; Jaffrezic, Anne; Fovet, Ophélie; Gruau, Gérard; Durand, Patrick

    2014-05-01

    Dissolved organic matter (DOM) is a key form of the organic matter linking together the water and the carbon cycles and interconnecting the biosphere (terrestrial and marine) and the soil. At the landscape scale, land use and hydrology are the main factors controlling the amount of DOM transferred from soils to the stream. In an intensively cultivated catchment, a recent work using isotopic composition of DOM as a marker has identified two different sources of DOM. The uppermost soil horizons of the riparian wetland appear as a quasi-infinite source while the topsoil of the hillslope forms a limited one mobilized by water-table rise and exported to the stream across the upland-riparian wetland-stream continuum. In addition to the exportation of DOM via water fluxes, climatic factors like temperature and precipitation regulate the DOM production by influencing microbial activity and soil organic matter degradation. The small headwater catchment (5 km²) of Kervidy-Naizin located in Brittany is part of the Environment Research Observatory (ORE) AgrHys. Weather and the hydro-chemistry of the stream, and the groundwater levels are daily recorded since 1993, 2000 and 2001 respectively. Over 13 contrasted hydrological years, the annual flow weighted mean concentration of dissolved organic carbon (DOC) is 5.6 mg.L-1 (sd = 0.7) for annual precipitation varying from 488mm to 1327mm and annual mean temperatures of 11°C (sd = 0.6). Based on this considerable dataset and this annual variability, we tried to understand how the hydro-climatic conditions determinate the stream DOC concentrations along the year. From the fluctuations of water table depth, each hydrologic year has been divided into three main period: i) progressive rewetting of the riparian wetland soils, ii) rising and holding high of the water table in the hillslope, iii) drawdown of the water-table, with less and less topsoil connected to the stream. Within each period base flow and storm flow data were first

  10. Response of sap flow to environmental factors in the headwater catchment of Miyun Reservoir in subhumid North China

    NASA Astrophysics Data System (ADS)

    Tie, Qiang; Hu, Hongchang; Tian, Fuqiang; Liu, Yaping; Xu, Ran

    2015-04-01

    Since the headwater catchment of Miyun Reservoir is the main drinking water conservation area of Beijing, its water cycle is of importance for the regional water resource. Transpiration is an important component of water cycle, which can be estimated by sap flow. In this study, the dynamics of sap flow and its response to environmental factors and relationship with leaf area index (LAI) were analyzed. The field study was conducted in the Xitaizi Experimental Catchment, located in the headwater catchment of Miyun Reservoir in subhumid North China. The Aspen (Populus davidiana) and Epinette (Larix gmelinii) are the two dominant tree species. Sap flow in 15 Aspen (Populus davidiana) trees was monitored using thermal dissipation probes (TDP) during the growing season of 2013 and 2014, and sap flow in another 3 Epinette (Larix gmelinii) trees was also monitored during September and October in 2014 for comparative analysis. Physiological and biometric parameters of the selected trees and the environmental factors, including meteorological variables, soil moisture content and groundwater table depth were measured. Vapor pressure deficit (VPD), variable of transpiration (VT) and reference crop evapotranspiration (ET0) were calculated using the measured environmental factors. The LAI, which is used to characterize phenophase, was calculated using the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI product (MCD15A3). Correlation analysis for daily sap flow and air temperature, relative humidity, precipitation, wind speed, solar radiation, VPD, VT and ET0 under different soil moisture and groundwater table depth conditions was performed. Diurnal course and hysteresis of sap flow were analyzed as a function of air temperature, solar radiation, VPD and VT on the typical sunny, cloudy and rainy days under different soil moisture conditions. Correlation analysis between daily sap flow and LAI showed that LAI and phenophase significantly influence sap flow and restrict

  11. Spatial variability in the isotopic composition of rainfall in a small headwater catchment and its effect on hydrograph separation

    NASA Astrophysics Data System (ADS)

    Fischer, Benjamin M. C.; van Meerveld, H. J. (Ilja); Seibert, Jan

    2017-04-01

    Isotope hydrograph separation (IHS) is a valuable tool to study runoff generation processes. To perform an IHS, samples of baseflow (pre-event water) and streamflow are taken at the catchment outlet. For rainfall (event water) either a bulk sample is collected or it is sampled sequentially during the event. For small headwater catchment studies, event water samples are usually taken at only one sampling location in or near the catchment because the spatial variability in the isotopic composition of rainfall is assumed to be small. However, few studies have tested this assumption. In this study, we investigated the spatiotemporal variability in the isotopic composition of rainfall and its effects on IHS results using detailed measurements from a small pre-alpine headwater catchment in Switzerland. Rainfall was sampled sequentially at eight locations across the 4.3 km2 Zwäckentobel catchment and stream water was collected in three subcatchments (0.15, 0.23, and 0.70 km2) during ten events. The spatial variability in rainfall amount, average and maximum rainfall intensity and the isotopic composition of rainfall was different for each event. There was no significant relation between the isotopic composition of rainfall and total rainfall amount, rainfall intensity or elevation. For eight of the ten studied events the temporal variability in the isotopic composition of rainfall was larger than the spatial variability in the rainfall isotopic composition. The isotope hydrograph separation results, using only one rain sampler, varied considerably depending on which rain sampler was used to represent the isotopic composition of event water. The calculated minimum pre-event water contributions differed up to 60%. The differences were particularly large for events with a large spatial variability in the isotopic composition of rainfall and a small difference between the event and pre-event water isotopic composition. Our results demonstrate that even in small catchments

  12. Using microbiological tracers to assess the impact of winter land use restrictions on the quality of stream headwaters in a small catchment.

    PubMed

    Flynn, Raymond M; Deakin, Jenny; Archbold, Marie; Cushnan, Hugh; Kilroy, Kate; O'Flaherty, Vincent; Misstear, Bruce D

    2016-01-15

    Diverse land use activities can elevate risk of microbiological contamination entering stream headwaters. Spatially distributed water quality monitoring carried out across a 17 km(2) agricultural catchment aimed to characterize microbiological contamination reaching surface water and investigate whether winter agricultural land use restrictions proved effective in addressing water quality degradation. Combined flow and concentration data revealed no significant difference in fecal indicator organism (FIO) fluxes in base flow samples collected during the open and prohibited periods for spreading organic fertilizer, while relative concentrations of Escherichia coli, fecal streptococci and sulfite reducing bacteria indicated consistently fresh fecal pollution reached aquatic receptors during both periods. Microbial source tracking, employing Bacteroides 16S rRNA gene markers, demonstrated a dominance of bovine fecal waste in river water samples upstream of a wastewater treatment plant discharge during open periods. This contrasted with responses during prohibited periods where human-derived signatures dominated. Differences in microbiological signature, when viewed with hydrological data, suggested that increasing groundwater levels restricted vertical infiltration of effluent from on-site wastewater treatment systems and diverted it to drains and surface water. Study results reflect seasonality of contaminant inputs, while suggesting winter land use restrictions can be effective in limiting impacts of agricultural wastes to base flow water quality.

  13. Thresholds in Subsurface Flow Generation: An Intercomparison of Three Different Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Hjerdt, K. N.; McGlynn, B.; Tromp-van Meerveld, I.; McDonnell, J. J.; Hooper, R. P.

    2001-12-01

    Dynamic thresholds in catchment response and subsurface stormflow initiation are poorly understood. This remains a problem for the generalization and transferability of hydrologic models, as well as for the simulation of catchment response under variable antecedent and input conditions. Threshold processes appear to operate both spatially and temporally within a catchment and introduce non-linearity to the system response function. We present a catchment intercomparison to illustrate the common features of threshold dynamics at the hillslope and catchment scales. While our overall goal is to generalize a model structure to work in humid areas where storm response is dominated by subsurface flow, cross-comparing internal catchment dynamics is a necessary prerequisite in order to define first order controls on the generation of subsurface stormflow across different landscape types. We analyzed physical data series collected from three catchments with extremely diverse climatic and physical characteristics: (1) Sleepers River Research Watershed in northeastern Vermont, USA; (2) Panola Mountain Research Watershed in central Georgia, USA; and (3) Maimai Watershed on the South Island of New Zeeland. The physical data series included continuous runoff, soil moisture probes, wells, piezometers and, for some catchments, tensiometers and hillslope trench flow. We calculated indices that characterized the timing, magnitude and duration of subsurface response in relation to stream discharge for a large number of events within each catchment. Analysis of these indices across space and time revealed distinguishable patterns of threshold behavior in the different catchments and our presentation will demonstrate the value of catchment intercomparision in this regard.

  14. Agricultural Catchments: Evaluating Policies and Monitoring Adaptive Management

    NASA Astrophysics Data System (ADS)

    Jordan, P.; Shortle, G.; Mellander, P. E.; Shore, M.; McDonald, N.; Buckley, C.

    2014-12-01

    Agricultural management in river catchments must combine the objectives of economic profit and environmental stewardship and, in many countries, mitigate the decline of water quality and/or maintain high water quality. Achieving these objectives is, amongst other activities, in the remit of 'sustainable intensification'. Of concern is the efficient use of crop nutrients, phosphorus and nitrogen, and minimising or offsetting the effects of transfers from land to water - corner-stone requirements of many agri-environmental regulations. This requires a robust monitoring programme that can audit the stages of nutrient inputs and outputs in river catchments and indicate where the likely points of successful policy interventions can be observed - or confounded. In this paper, a catchment, or watershed, experimental design and results are described for monitoring the nutrient transfer continuum in the Irish agricultural landscape against the backdrop of the European Union Nitrates and Water Framework Directives. This Agricultural Catchments Programme experimental design also serves to indicate water quality pressure-points that may be catchment specific as agricultural activities intensify to adapt to national efforts to build important parts of the post-recession economy.

  15. The relationship between soil heterotrophic activity, soil dissolved organic carbon (DOC) leachate, and catchment-scale DOC export in headwater catchments

    USGS Publications Warehouse

    Brooks, P.D.; McKnight, Diane M.; Bencala, K.E.

    1999-01-01

    Dissolved organic carbon (DOC) from terrestrial sources forms the major component of the annual carbon budget in many headwater streams. In high-elevation catchments in the Rocky Mountains, DOC originates in the upper soil horizons and is flushed to the stream primarily during spring snowmelt. To identify controls on the size of the mobile soil DOC pool available to be transported during the annual melt event, we measured soil DOC production across a range of vegetation communities and soil types together with catchment DOC export in paired watersheds in Summit County, Colorado. Both surface water DOC concentrations and watershed DOC export were lower in areas where pyrite weathering resulted in lower soil pH. Similarly, the amount of DOC leached from organic soils was significantly smaller (p < 0.01) at sites having low soil p H. Scaling point source measurements of DOC production and leaching to the two basins and assuming only vegetated areas contribute to DOC production, we calculated that the amount of mobile DOC available to be leached to surface water during melt was 20.3 g C m-2 in the circumneutral basin and 17.8 g C m-2 in the catchment characterized by pyrite weathering. The significant (r2 = 0.91 and p < 0.05), linear relationship between overwinter CO2 flux and the amount of DOC leached from upper soil horizons during snowmelt suggests that the mechanism for the difference in production of mobile DOC was heterotrophic processing of soil carbon in snow-covered soil. Furthermore, this strong relationship between over-winter heterotrophic activity and the size of the mobile DOC pool present in a range of soil and vegetation types provides a likely mechanism for explaining the interannual variability of DOC export observed in high-elevation catchments.

  16. Groundwater head controls nitrate export from an agricultural lowland catchment

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Schmidt, Christian; Rode, Michael; Lischeid, Gunnar; Weise, Stephan M.; Fleckenstein, Jan H.

    2016-10-01

    Solute concentration variability is of fundamental importance for the chemical and ecological state of streams. It is often closely related to discharge variability and can be characterized in terms of a solute export regime. Previous studies, especially in lowland catchments, report that nitrate is often exported with an accretion pattern of increasing concentrations with increasing discharge. Several modeling approaches exist to predict the export regime of solutes from the spatial relationship of discharge generating zones with solute availability in the catchment. For a small agriculturally managed lowland catchment in central Germany, we show that this relationship is controlled by the depth to groundwater table and its temporal dynamics. Principal component analysis of groundwater level time series from wells distributed throughout the catchment allowed derivation of a representative groundwater level time series that explained most of the discharge variability. Groundwater sampling revealed consistently decreasing nitrate concentrations with an increasing thickness of the unsaturated zone. The relationships of depth to groundwater table to discharge and to nitrate concentration were parameterized and integrated to successfully model catchment discharge and nitrate export on the basis of groundwater level variations alone. This study shows that intensive and uniform agricultural land use likely results in a clear and consistent concentration-depth relationship of nitrate, which can be utilized in simple approaches to predict stream nitrate export dynamics at the catchment scale.

  17. The use of novel wooden structures to manage flooding and coarse sediment problems in responsive upland headwater catchments

    NASA Astrophysics Data System (ADS)

    Wilkinson, Mark; Addy, Steve; Ghimire, Sohan; Watson, Helen; Stutter, Marc

    2014-05-01

    Over the past decade economic losses from floods have greatly increased, with sediment related impacts as a key feature of such events. Impacts include changes in river channel course, scour of river banks, sedimentation of infrastructure (e.g. bridges), and deposition of sand and gravel on farmland. Sediment deposition can in turn reduce conveyance capacity and lead to further increased flood risk. The EU Water Framework Directive and Floods Directive highlights that sustainable approaches to flood risk reduction should be used alongside and, where possible, replace traditional structural flood defences and activities that address sediment problems. Natural Flood Management(NFM) is promoted as a method that can reduce flood risk and manage sediment by incorporating natural hydrological and morphological processes. As such, NFM measures are designed to use these fluvial processes to manage the sources and pathways of flood waters and sediments. Techniques include the restoration, enhancement and alteration of natural features and characteristics, but exclude traditional flood defence engineering that works against or disrupts these natural processes. Here we aim to assess the effectiveness of novel flood mitigation measures for reducing flood risk and capturing coarse sediment in rapidly responding headwater catchments. We present preliminary research findings from a densely instrumented research site (Bowmont catchment, Scotland (85km2)) which regularly experiences flood events with associated coarse sediment problems. NFM measures have been installed to capture course sediment and to store water more effectively on the flood plains during these flood events. For example, novel engineered wooden structures ('bar apex log jams') constructed in the river corridor are designed to trap sediment and log bank protection structures have been installed to stop bank erosion. Within a tributary catchment of the Bowmont (0.7km2), new flow restrictors have been installed on a

  18. A High Resolution, Integrated Approach to Modeling Climate Change Impacts to a Mountain Headwaters Catchment using ParFlow

    NASA Astrophysics Data System (ADS)

    Pribulick, C. E.; Maxwell, R. M.; Williams, K. H.; Carroll, R. W. H.

    2014-12-01

    Prediction of environmental response to global climate change is paramount for regions that rely upon snowpack for their dominant water supply. Temperature increases are anticipated to be greater at higher elevations perturbing hydrologic systems that provide water to millions of downstream users. In this study, the relationships between large-scale climatic change and the corresponding small-scale hydrologic processes of mountainous terrain are investigated in the East River headwaters catchment near Gothic, CO. This catchment is emblematic of many others within the upper Colorado River Basin and covers an area of 250 square kilometers, has a topographic relief of 1420 meters, an average elevation of 3266 meters and has varying stream characteristics. This site allows for the examination of the varying effect of climate-induced changes on the hydrologic response of three different characteristic components of the catchment: a steep high-energy mountain system, a medium-grade lower-energy system and a low-grade low-energy meandering floodplain. To capture the surface and subsurface heterogeneity of this headwaters system the basin has been modeled at a 10-meter resolution using ParFlow, a parallel, integrated hydrologic model. Driven by meteorological forcing, ParFlow is able to capture land surface processes and represents surface and subsurface interactions through saturated and variably saturated heterogeneous flow. Data from Digital Elevation Models (DEMs), land cover, permeability, geologic and soil maps, and on-site meteorological stations, were prepared, analyzed and input into ParFlow as layers with a grid size comprised of 1403 by 1685 cells to best represent the small-scale, high resolution model domain. Water table depth, soil moisture, soil temperature, snowpack, runoff and local energy budget values provide useful insight into the catchments response to the Intergovernmental Panel on Climate Change (IPCC) temperature projections. In the near term

  19. Modelling Cryptosporidium oocysts transport in small ungauged agricultural catchments.

    PubMed

    Tang, Jialiang; McDonald, Stephen; Peng, Xinhua; Samadder, Sukha R; Murphy, Thomas M; Holden, Nicholas M

    2011-06-01

    Cryptosporidium is an environmentally robust pathogen that has caused severe waterborne disease outbreaks worldwide. The main source of zoonotic Cryptosporidium parvum oocysts in human drinking water is likely to be from farm animals via catchment pathways with water as the main transport vector. The vast majority of small agricultural catchments are ungauged therefore it is difficult to use a process model to predict and understand the mechanisms and activities that regulate the risk of surface water contamination from agricultural areas. For this study, two ungauged agricultural catchments in Ireland were used to model Cryptosporidium oocyst transport using SWAT2005 on a daily basis with reference data from adjacent catchment gauging stations. The results indicated that SWAT2005 could simulate stream flow with good agreement between prediction and observation on a monthly basis (R(2) from 0.94 to 0.83 and E (efficiency) from 0.92 to 0.66), but Cryptosporidium oocyst concentration results were less reliable (R(2) from 0.20 to 0.37, P < 0.05; with poor E -0.37 to -2.57). A sensitivity analysis using independent parameter perturbation indicated that temperature was the most important parameter regulating oocyst transport in the study catchments and that the timing of manure application relative to the occurrence of water runoff event was critical. The results also showed that grazing management had little influence on predicted oocyst transport while fields fertilized with manure were the key critical source areas for microbial contaminations in the study catchments. It was concluded that the approach presented could be used to assist with understanding the epidemiology of waterborne cryptosporidiosis outbreaks and to improve catchment management for the safety of the general public health.

  20. Temporal and spatial dynamics of carbon and nitrogen in headwater snow-dominated catchments, Jemez Mountains, New Mexico

    NASA Astrophysics Data System (ADS)

    Dannemann, F. K.; Zapata, X.; McIntosh, J. C.; Perdrial, J. N.; Brooks, P. D.; Chorover, J.; Lohse, K. A.; Fricke, H. C.

    2011-12-01

    The concentration and availability of stream nutrients, particularly dissolved organic carbon (DOC) and nitrogen species, determine aquatic system productivity, and are important indicators of catchment hydrobiogeochemical processes. In semi-arid montane areas, such as the Valles Caldera National Preserve located within the Jemez River Basin, NM, an understanding of the relationship between discharge and nutrient concentrations is particularly important. Although the annual hydrograph is dominated (~40%) by spring snowmelt, similar to well studies sites in the northern Rockies, the JRB region receives a much larger percentage of precipitation associated with summer rainfall, and consequently may provide insight into how more northerly catchments will respond to changing climate. This study focuses on four headwater catchments: History Grove, La Jara, Upper Jaramillo and Upper Redondo, over two water years (2009 to 2011) to examine how nutrient concentrations vary as a function of hillslope aspect, catchment hydrologic responses, seasonality, and discharge. Stream water grab samples were collected on a monthly to weekly basis from 2009 to 2011 and analyzed for inorganic carbon (DIC), dissolved organic carbon (DOC) and nitrogen species (total dissolved nitrogen (DN), NO3, NO2, NH4). DOC and DN concentrations in stream waters from all 4 catchments are positively correlated, indicating a tight coupling of carbon and nitrogen. During dry periods (September to February) stream waters have high DIC (4.8-7.6 mg/L), and low DOC (1.6-2.7 mg/L) and DN (<0.3 mg/L) concentrations, indicating that stream water is dominated by groundwater inputs. In contrast, during spring snowmelt (March-May) stream waters have high DOC (2.9-6.2 mg/L) and DN (0.2-0.5mg/L) concentrations and low DIC (3.1-4.5mg/L) values; the majority of DN is comprised of organic-N. These results suggest flushing of shallow soil waters during snowmelt periods. High DIC (5.8-6.3mg/L), and low DOC (1.7-4.0mg/L) and

  1. Two water worlds in temperate forests? Partitioning of water sources in two forested headwater catchments in Germany

    NASA Astrophysics Data System (ADS)

    Schmid, Bettina; Dubbert, Maren; Werner, Christiane; Hopp, Luisa

    2016-04-01

    Recent ecohydrological studies using stable isotopes have suggested that water used by plants is largely separated from water that is returned to streams and groundwater. These observations have led to the postulation of a "two water worlds hypothesis" with distinct reservoirs of water in the subsurface that are not well mixed. This has major implications for our understanding of the water cycle and its conceptualization. Most of the studies to date have been conducted in forested catchments located in regions with a pronounced seasonal distribution of precipitation. Here we present findings from a study of the ecological separation of water in two forested headwater catchments in Germany where precipitation is distributed rather evenly throughout the year. Over the course of 18 months we sampled plant water, soil water, groundwater and stream runoff monthly to analyze isotope ratios of 18O and 2H. Plant and soil water were cryogenically extracted, and isotope ratios in the water samples were analyzed using cavity ring-down spectroscopy and isotope-ratio mass spectrometry. The isotope ratios of the different water sources were used to test the hypothesis that separate water worlds also exist in climates that do not exhibit a seasonal distribution of precipitation. First findings indicate distinct differences in isotope ratios between tree species, suggesting complex processes at the biosphere-hydrosphere interface, but otherwise little evidence for the existence of separate water reservoirs.

  2. Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

    NASA Astrophysics Data System (ADS)

    Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

    2016-04-01

    Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

  3. Factors influencing water transit times in snowmelt-dominated, headwater catchments of the western U.S.

    NASA Astrophysics Data System (ADS)

    Clow, D. W.; Mast, A.

    2015-12-01

    In catchments, water transit times (TTs) refer to the elapsed time between entry of water at the ground surface and exit of water at the catchment outlet. Transit times are an important characteristic of catchments in that they reflect the time available for interaction between water, soil, and biota within the system. Thus, they exert a strong influence on hydrologic resilience to drought and climate change, and on the sensitivity of aquatic ecosystems to atmospheric pollutants. Transit times may vary spatially due to variations in basin characteristics, such as slope, size, and amount and type of soil and vegetation; however, the relative influence of these factors on TTs is poorly known. In this study, we estimate mean transit times (MTTs) for 11 snowmelt-dominated, headwater catchments in the western U.S. using the convolution integral approach, which relies on differences in the magnitude of seasonal variability in δ18O in precipitation and stream water to estimate MTTs. Seasonal variability in δ18O was calculated based on analyses of precipitation and stream water samples collected at weekly to monthly intervals. Results indicate that MTTs ranged from 0.6 to 2.1 years, and were positively influenced by percent of the catchment covered by forest (r2 = 0.56; p = 0.008), and negatively influenced by barren terrain (e.g., bedrock; r2 = 0.48; p = 0.019). MTTs showed a weak negative relation to mean basin slope (r2 = 0.31; p = 0.076) and no relation to basin size or elevation. These results illustrate the importance of soil as a key factor influencing MTTs, with basin slope acting as a secondary influence. Heavily forested basins tend to have deep, well-developed soils with substantial water storage capacity; these soils help maintain baseflow during drought conditions, providing hydrologic resilience to the system, and they are an important location for geochemical and biological processes that neutralize acidity and assimilate atmospherically deposited nitrogen

  4. Development and Application of a Simple Hydrogeomorphic Model for Headwater Catchments

    EPA Science Inventory

    We developed a catchment model based on a hydrogeomorphic concept that simulates discharge from channel-riparian complexes, zero-order basins (ZOB, basins ZB and FA), and hillslopes. Multitank models simulate ZOB and hillslope hydrological response, while kinematic wave models pr...

  5. Effects of a beaver pond on runoff processes: comparison of two headwater catchments

    USGS Publications Warehouse

    Burns, Douglas A.; McDonnell, Jeffery J.

    1998-01-01

    Natural variations in concentrations of 18O, D, and H4SiO4 in two tributary catchments of Woods Lake in the west-central Adirondack Mountains of New York were measured during 1989–1991 to examine runoff processes and their implications for the neutralization of acidic precipitation by calcium carbonate treatment. The two catchments are similar except that one contained a 1.3 ha beaver pond. Evaporation from the beaver pond caused a seasonal decrease in the slope of the meteoric water line in stream water from the catchment with a beaver pond (WO2). No corresponding change in slope of the meteoric water line was evident in stream water from the other catchment (WO4), nor in ground water nor soil water from either catchment, indicating that evaporative fractionation was not significant. Application of a best-fit sine curve to δ18O data indicated that base flow in both catchments had a residence time of about 100 days. Ground water from a well finished in thick till had the longest residence time (160 days); soil water from the O-horizon and B-horizon had residence times of 63 and 80 days, respectively. Water previously stored within each catchment (pre-event water) was the predominant component of streamflow during spring snowmelt and during spring and autumn rainfall events, but the proportion of streamflow that consisted of pre-event water differed significantly in the two catchments. The proportion of event water (rain and snowmelt) in WO2 was smaller than at WO4 early in the spring snowmelt of March 13–17, 1990, but the proportions of source water components for the two catchments were almost indistinguishable by the peak flow on the third day of the melt. The event water was further separated into surface-water and subsurface-water components by utilizing measured changes in H4SiO4 concentrations in stream water during the snowmelt. Results indicated that subsurface flow was the dominant pathway by which event water reached the stream except during the

  6. Shallow subsurface storm flow in a forested headwater catchment: Observations and modeling using a modified TOPMODEL

    USGS Publications Warehouse

    Scanlon, T.M.; Raffensperger, J.P.; Hornberger, G.M.; Clapp, R.B.

    2000-01-01

    Transient, perched water tables in the shallow subsurface are observed at the South Fork Brokenback Run catchment in Shenandoah National Park, Virginia. Crest piezometers installed along a hillslope transect show that the development of saturated conditions in the upper 1.5 m of the subsurface is controlled by total precipitation and antecedent conditions, not precipitation intensity, although soil heterogeneities strongly influence local response. The macroporous subsurface storm flow zone provides a hydrological pathway for rapid runoff generation apart from the underlying groundwater zone, a conceptualization supported by the two-storage system exhibited by hydrograph recession analysis. A modified version of TOPMODEL is used to simulate the observed catchment dynamics. In this model, generalized topographic index theory is applied to the subsurface storm flow zone to account for logarithmic storm flow recessions, indicative of linearly decreasing transmissivity with depth. Vertical drainage to the groundwater zone is required, and both subsurface reservoirs are considered to contribute to surface saturation.

  7. Nitrogen attenuation along delivery pathways in agricultural catchments

    NASA Astrophysics Data System (ADS)

    McAleer, Eoin; Mellander, Per-Erik; Coxon, Catherine; Richards, Karl G.

    2014-05-01

    Hillslope hydrologic systems and in particular near-stream saturated zones are active sites of nitrogen (N) biogeochemical dynamics. The efficiency of N removal and the ratio of reaction products (nitrous oxide and dinitrogen) in groundwater is highly variable and depends upon aquifer hydrology, mineralogy, dissolved oxygen, energy sources and redox chemistry. There are large uncertainties in the closing of N budgets in agricultural catchments. Spatial and temporal variability in groundwater physico-chemistry, catchment hydrology and land-use gives rise to hotspots and hot moments of N attenuation. In addition the production, consumption and movement of denitrification products remains poorly understood. The focus of this study is to develop a holistic understanding of N dynamics in groundwater as it moves from the top of the hillslope to the stream. This includes saturated groundwater flow, exchange at the groundwater-surface water interface and hyporheic zone flow. This project is being undertaken in two ca. 10km2 Irish catchments, characterised by permeable soils. One catchment is dominated by arable land overlying slate bedrock and the other by grassland overlying sandstone. Multi-level monitoring wells have been installed at the upslope, midslope and bottom of each hillslope. The piezometers are screened to intercept the subsoil, weathered bedrock and competent bedrock zones. Groundwater samples for nitrate (NO3-N) nitrite (NO2-N), ammonium (NH4-N) and total nitrogen are collected on a monthly basis while dissolved gas concentrations are collected seasonally. Groundwater NO3-N profiles from monitoring data to date in both catchments differ markedly. Although the two catchments had similar 3 year mean concentrations of 6.89 mg/L (arable) and 6.24 mg/L (grassland), the grassland catchment had higher spatial and temporal variation. The arable catchment showed relatively homogenous NO3-N concentrations in all layers and zones (range: 1.2 - 12.13 mg/L, SD = 1.60 mg

  8. Hydroclimatic influences on non-stationary transit time distributions in a boreal headwater catchment

    NASA Astrophysics Data System (ADS)

    Peralta-Tapia, A.; Soulsby, C.; Tetzlaff, D.; Sponseller, R.; Bishop, K.; Laudon, H.

    2016-12-01

    Understanding how water moves through catchments - from the time it enters as precipitation to when it exits via streamflow - is of fundamental importance to understanding hydrological and biogeochemical processes. A basic descriptor of this routing is the Transit Time Distribution (TTD) which is derived from the input-output behavior of conservative tracers, the mean of which represents the average time elapsed between water molecules entering and exiting a flow system. In recent decades, many transit time studies have been conducted, but few of these have focused on snow-dominated catchments. We assembled a 10-year time series of isotopic data (δ18O and δ2H) for precipitation and stream water to estimate the characteristics of the transit time distribution in a boreal catchment in northern Sweden. We applied lumped parameter models using a gamma distribution to calculate the Mean Transit Time (MTT) of water over the entire period of record and to evaluate how inter-annual differences in transit times relate to hydroclimatic variability. The best fit MTT for the complete 10-year period was 650 days (Nash-Sutcliff Efficiency = 0.65), while the best fit inter-annual MTT ranged from 300 days up to 1200 days. Whilst there was a weak negative correlation between mean annual total precipitation and the annual MTT, this relationship was stronger (r2 = 0.53, p = 0.02) for the annual rain water input. This strong connection between the MTT and annual rainfall, rather than snowmelt, has strong implications for understanding future hydrological and biogeochemical processes in boreal regions, given that predicted warmer winters would translate into a greater proportion of precipitation falling as rain and thus shorter MTT in catchments. Such a change could have direct implications for the export of solutes and pollutants.

  9. Factors Controlling the Metal Levels in Headwater Stream Draining an Agroforestry Catchment (Galicia, NW Spain)

    NASA Astrophysics Data System (ADS)

    Palleiro, Laura; Rodríguez-Blanco, M. Luz; Mercedes Taboada-Castro, M.; Taboada-Castro, M. Teresa

    2016-10-01

    Concentrations of Al, Fe, Mn, Cu and Zn (dissolved and particulate), suspended sediment, dissolved organic carbon, and pH and discharge were determined during a 3-year period in a stream water of an agroforestry catchment in Galicia (NW Spain). The objective of this study is to investigate the role of these variables in the control of dissolved and particulate concentrations of each metal in the stream water. The soils in the catchment are developed on metamorphic schist. Stream water samples were collected at the catchment outlet every 15 days and more frequently with increased stream flows. Metal concentrations were measured by ICP- MS. Pearson correlation coefficients were calculated to examine the possible associations between metals and the four variables under consideration. Stepwise multiple regressions were applied to determine which predictor variables have the strongest influences on controlling concentrations of each metal in the stream. The results showed that metal concentrations were relatively low (Fe > Al > Mn > Zn > Cu), but particulate metals were predominant over those dissolved. Stepwise multiple regression analysis revealed that the most important variable to explain dissolved concentrations for Al, Fe and Cu was the dissolved organic carbon, whereas the suspended sediment was for dissolved Zn and the discharge was for dissolved Mn. The suspended sediment was also a good predictor of particulate metal levels.

  10. Influence of Terrain and Land Cover on the Isotopic Composition of Seasonal Snowpack in Rocky Mountain Headwater Catchments Affected by Bark Beetle Induced Tree Mortality

    NASA Astrophysics Data System (ADS)

    Kipnis, E. L.; Murphy, M.; Klatt, A. L.; Miller, S. N.; Williams, D. G.

    2015-12-01

    Session H103: The Hydrology-Vegetation-Climate Nexus: Identifying Process Interactions and Environmental Shifts in Mountain Catchments Influence of Terrain and Land Cover on the Isotopic Composition of Seasonal Snowpack in Rocky Mountain Headwater Catchments Affected by Bark Beetle Induced Tree Mortality Evan L Kipnis, Melanie A Murphey, Alan Klatt, Scott N Miller, David G Williams Snowpack accumulation and ablation remain difficult to estimate in forested headwater catchments. How physical terrain and forest cover separately and interactively influence spatial patterns of snow accumulation and ablation largely shapes the hydrologic response to land cover disturbances. Analysis of water isotopes in snowpack provides a powerful tool for examining integrated effects of water vapor exchange, selective redistribution, and melt. Snow water equivalence (SWE), δ2H, δ18O and deuterium excess (D-excess) of snowpack were examined throughout winter 2013-2014 across two headwater catchments impacted by bark beetle induced tree mortality. A USGS 10m DEM and a derived land cover product from 1m NAIP imagery were used to examine the effects of terrain features (e.g., elevation, slope, aspect) and canopy disturbance (e.g., live, bark-beetle killed) as predictors of D-excess, an expression of kinetic isotope effects, in snowpack. A weighting of Akaike's Information Criterion (AIC) values from multiple spatially lagged regression models describing D-excess variation for peak snowpack revealed strong effects of elevation and canopy mortality, and weaker, but significant effects of aspect and slope. Snowpack D-excess was lower in beetle-killed canopy patches compared to live green canopy patches, and at lower compared to high elevation locations, suggesting that integrated isotopic effects of vapor exchange, vertical advection of melted snow, and selective accumulation and redistribution varied systematically across the two catchments. The observed patterns illustrate the potential

  11. Multiscale soil moisture measurement for mapping surface runoff generation on torrential headwater catchments (Draix-Bléone field observatory, South Alps, France)

    NASA Astrophysics Data System (ADS)

    Florian, Mallet; Vincent, Marc; Johnny, Douvinet; Philippe, Rossello; Bouteiller Caroline, Le; Jean-Philippe, Malet; Julien, Gance

    2015-04-01

    Runoff generation in the headwater catchments in various land use conditions still remain a core issue in catchment hydrology (Uhlenbrook S. et al., 2003). Vegetation has a strong impact on flows distribution (interception, infiltration, evapotranspiration, runoff) but the relative influence of these mechanisms according to geomorphological determinants is still not totally understood. The "ORE Draix" located in the Alpes-de-Haute-Provence (France) allows to study these parameters using experimental watersheds equipped with a long term monitoring instrumentation (rainfall, streamflow, water, soil and air temperature, soil erosion, soil moisture...). These marl torrential watersheds have a peculiar hydrological behavior during flood events with large outflow differences between the wooded and the bare areas. We try to identify the runoff production factors by studying water storage/drainage processes within the first 30 cm depth of soil (Wilson et al., 2003, Western et al., 2004). Soil moisture can explain runoff during floods, that's why we try to upscale this variable at the watershed level. Unlike studies on soil moisture monitoring in agricultural context (flat areas), conventional remote sensing methods are difficult to apply to the badlands (elevation between 1500 masl and 1800 masl, approximately 1km² areas, steep slopes, various land uses) (Bagdhadi, 2005). This difficulty can be overcome by measuring soil moisture at different spatial (point, plot, slope, catchment) and time scales (event, season, year) using innovative approaches. In this context, we propose a monitoring of soil moisture based on geostatistical treatments crossed with measurements at different scales. These measures are provided from ground and airborne sensors deployment. Point measurements are ensured at a very high time frequency using capacitance probes. At an intermediate level, a slope is equipped with a DTS sensor (distributed temperature sensing) to obtain a 2D estimate of

  12. Impact of forest disturbance on the runoff response in headwater catchments. Case study: Sumava mountains, Czech republic

    NASA Astrophysics Data System (ADS)

    Langhammer, Jakub; Hais, Martin; Bartunkova, Kristyna; Su, Ye

    2013-04-01

    The forest disturbance and stream modifications are important phenomenon affecting the natural dynamics of erosion and sedimentation processes on montane and submontane streams. The changes in land use, land cover structure, forest cover and stream modifications, occurring in the cultural landscape have significant effect on the dynamics of fluvial processes, especially in relation to the extreme runoff events. The contribution discusses the relations between forest disturbance and fluvial dynamics, stemming from the research in Sumava Mountains, located at the border between Czech Republic and Germany, Central Europe. The study area is located in headwater region, affected by different types of forest disturbance in past three decades - bark beetle outbreak, repeated windstorms and clear-cut forest management. The streams in experimental catchments here displayed extensive dynamics of erosion and sedimentation after the extreme floods in 2002 and 2009 and were affected by artificial modifications. The analysis is based on the combination of different research techniques, including remote sensed data processing, network of automated high frequency rainfall-runoff monitoring or field survey of stream modifications and geomorphologic changes on riverbeds after extreme events. Using landsat satellite data and aerial photographs we created model of Bark beetle dispersion and clear-cutting between 1985 and 2007. This model enables to describe disturbance dynamic, which is needed for understanding of nature those processes. Next analysis of Landsat satellite data was used to detect the effect of forest disturbance on the wetness and temperature properties of land cover, affected by two significant different types of forest disturbance - bark beetle outbreak and clear cut. The rainfall-runoff analysis using multivariate geostatistical techniques was focused on experimental catchments with similar conditions of climate, physiography and topography but different type

  13. Influence of teleconnection on water quality in agricultural river catchments

    NASA Astrophysics Data System (ADS)

    Mellander, Per-Erik; Jordan, Phil; Shore, Mairead; McDonald, Noeleen; Shortle, Ger

    2015-04-01

    Influences such as weather, flow controls and lag time play an important role in the processes influencing the water quality of agricultural catchments. In particular weather signals need to be clearly considered when interpreting the effectiveness of current measures for reducing nitrogen (N) and phosphorus (P) losses from agricultural sources to water bodies. In north-western Europe weather patterns and trends are influenced by large-scale systems such as the North Atlantic Oscillation (NAO) and the position of the Gulf Stream, the latter expressed as the Gulf Stream North Wall index (GSNW index). Here we present five years of monthly data of nitrate-N concentration in stream water and groundwater (aggregated from sub-hourly monitoring in the stream outlet and monthly sampling in multilevel monitoring wells) from four agricultural catchments (ca. 10 km2) together with monitored weather parameters, long-term weather data and the GSNW index. The catchments are situated in Ireland on the Atlantic seaboard and are susceptible to sudden and seasonal shifts in oceanic climate patterns. Rain anomalies and soil moisture deficit dynamics were similar to the dynamics of the GSNW index. There were monitored changes in nitrate-N concentration in both groundwater and surface water with no apparent connection to agricultural management; instead such changes also appeared to follow the GSNW index. For example, in catchments with poorly drained soils and a 'flashy hydrology' there were seasonal dynamics in nitrate-N concentration that correlated with the seasonal dynamics of the GSNW index. In a groundwater driven catchment there was a consistent increase in nitrate-N concentration over the monitored period which may be the result of increasingly more recharge in summer and autumn (as indicated by more flux in the GSNW index). The results highlight that the position of the Gulf Stream may influence the nitrate-N concentration in groundwater and stream water and there is a risk

  14. Spatial and temporal variations in the effects of soil depth and topographic wetness index of bedrock topography on subsurface saturation generation in a steep natural forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Liang, Wei-Li; Chan, Meng-Chun

    2017-03-01

    Subsurface saturation near the bedrock surface is an important source of runoff generation and deeper bedrock recharge. While many studies have reported the generation patterns of subsurface saturation on valley side slopes or unchanneled catchments, studies focusing on the relationship between bedrock topography and subsurface saturation dynamics in a headwater catchment are still rare. This study therefore analyzed the effects of bedrock topographic features on subsurface saturation generation based on a dataset of pore water pressure (ψ) observations at the soil-bedrock interface and the spatial distributions of soil depth and the topographic wetness index (TWI) of bedrock topography in a steep natural forested headwater catchment. Temporal variations in the mean and standard deviation of ψ were lower at the perennially saturated points but higher at the ephemerally saturated points. The expansion patterns of subsurface saturation during storm events could be classified into four stages: fragmentary and unconnected distributions, both downward and upward expansions, interconnection from upslope to downslope, and disappearance from the middle slope. When saturation was interconnected, 41% of accumulated rainfall contributed to increases of subsurface saturation with a highly linear relationship. Soil depth correlated negatively with the increase in ψ at all points and at ephemerally saturated points. These negative correlations occurred frequently after the generation of new saturation, and remained for a short period around the early peaks of rainfall when the mean of ψ increased sharply. TWI correlated positively with ψ and ψ ⩾ 0 among all points but not in the subsets of perennially or ephemerally saturated points. The positive correlations became more significant after generation of new saturation. Overall, this study demonstrates that the effects of soil depth and TWI on subsurface saturation vary with space and time in a steep natural forested

  15. Stream Ammonium Uptake Across Scales in Headwater Catchments of a Tropical Rainforest, Luquillo Mountains, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Brereton, R. L.; McDowell, W. H.; Wymore, A.

    2015-12-01

    Many tropical forest streams export high amounts of nitrogen relative to streams draining undisturbed watersheds of other biomes. With their low DOC concentrations and high rates of respiration, headwater streams in the Luquillo Mountains have been previously characterized as energy-limited, suggesting that NH4+ uptake is dominated not by N demand but by energy demand. In the Rio Icacos watershed, high concentrations of NH4+ (>1 mg N/L) are found in groundwater adjacent to the streams, making high inputs of NH4+ to the stream channel via groundwater seepage likely. Stream nutrient spiraling metrics can be used to quantify uptake and retention rates of specific nutrients, and can be measured by solute additions. Tracer Additions for Spiraling Curve Characterization (TASCC) is a recently developed method (Covino et al. 2010) for quantifying nutrient uptake with a single slug addition of nutrient and conservative tracer. Here we present NH4+ uptake metrics from TASCC additions in three Luquillo streams of different sizes, ranging from 2nd to 4th order: the Rio Icacos, a larger, 3rd order tributary and a smaller 2nd order tributary. Background NH4+ concentrations vary by up to an order of magnitude, with highest concentrations (27 μg N/L) found in the smaller tributary. Background DOC concentrations are uniformly low and show no difference between the three streams (500-600 μg C/L). The smaller tributary has the shortest uptake length (155 m) and highest uptake velocity (2.9 mm/min) of the three streams. Unexpectedly, the Rio Icacos has a higher uptake velocity (1.7 mm/min) than the larger tributary (1.0 mm/min), despite having an uptake length more than double (1400 m) that of the larger tributary (596 m). Overall, NH4+ uptake is substantial in all three streams and varies with background concentrations, not stream size.

  16. Non-free ionic transport of sodium, magnesium, and calcium in streams of two adjacent headwater catchments with different vegetation types in Japan

    NASA Astrophysics Data System (ADS)

    Terajima, Tomomi; Moriizumi, Mihoko; Nakamura, Tomohiro

    2017-01-01

    Sodium (Na), magnesium (Mg), calcium (Ca) are usually believed to occur mostly as free ions in the fresh water and consequently little is known about their chemical species. To understand the importance of non-free ionic fractions (NIF) of major metals in freshwater streams, Na, Mg, Ca, silicon (Si), and fulvic acid-like materials (FAM) were measured in streams of mountainous adjacent headwater catchments dominated by different vegetation types (planted evergreen coniferous forest and natural deciduous broadleaf forest). During both no rainfall periods and rainstorms, the proportion of NIF relative to total elements was lower in the coniferous catchment than in the deciduous catchment, although it sometimes accounted for half or more of the total concentrations of Na, Mg, and Ca in both catchments. The solubility of metal compounds was higher than the measured maximum concentrations of Na+, Mg2+, and Ca2+ to the extent that inorganic bonding was hardly possible. During no rainfall periods when FAM was slightly produced into the streams, the fluxes of NIF and Si were highly correlated (r > 0.92, p < 0.0001, n = 30) in both catchments. During a small rainstorm, the flux of NIF correlated weakly with that of Si but did not correlate with that of FAM in both catchments. In contrast, during a heavy rainstorm, the flux of NIF correlated strongly (r ⩾ 0.83, p < 0.0001, n = 26) with that of FAM in the deciduous catchment where relatively deep soil water compared to near-surface water was the predominant component of stream water. However, during the heavy rainstorm in the coniferous catchment, only the flux of NIF originated in the quick-flow component (i.e., surface or near-surface water) in stream water (ΔNIF) correlated strongly (r ⩾ 0.81, p < 0.0001, n = 22) with that of FAM. These findings imply that heavy rainstorms may enhance the bonding of the major metals with humic substances mainly in the deciduous catchment; and also exhibit that, in the headwater

  17. Diurnal variation of dominant nitrate retention processes in an agricultural headwater stream

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Ryabenko, Evgenia; Stumpp, Christine

    2015-04-01

    Nitrate and ammonium are introduced by agricultural practice into the environment and are transformed and retained on their pathway through aquatic environments. In particular, biological transformation processes (i.e. microbial denitrification or ammonium oxidation and assimilation) are responsible for the largest part of nitrate removal, which are also crucial processes in headwater streams. It is well known, that most of the biological processes are influenced by available (solar) energy fluxes, temperatures and dissolved oxygen concentrations, which vary with time and space. However, looking at biogeochemical hot spots in the landscapes` hydrological interface, the stream and river network (e.g. stream sections with a high biological activity), the temporal variability of biological processes can be an important control on total nitrate export. In this study, we therefore identified most important diurnal time periods for nitrate retention in a 75 m impervious section of an agricultural headwater stream using oxygen saturation dynamics and nitrate isotopes. We regularly measured discharge, hydro-geochemical and climate parameters, as well as nitrate and water isotopes in grab samples at three locations along the reach. On average, we observed a decrease of 10% in nitrate concentration from up- to downstream, which was only caused by biological processes and not by dilution. Nitrate isotope analysis indicated distinct trends along the reach and with time of the day. Both nitrate assimilation and nitrification caused significant changes in nitrate isotope distribution in the early day. To explain the distinct observed process dynamics from the morning to the afternoon, we simulated net primary production (NEP) and respiration using the river metabolism model RIVERMETC with observed oxygen concentrations and water temperatures. Comparing the results with the observed nitrate dynamics, the short time period when NEP occurs (~10:30 -12:30) seems to be crucial for

  18. Geochemical investigation of weathering processes in a forested headwater catchment: Mass-balance weathering fluxes

    USGS Publications Warehouse

    Jones, B.F.; Herman, J.S.

    2008-01-01

    Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basic hydrology. O'Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile. ?? 2008 The Mineralogical Society.

  19. Discharge process of cesium during rainstorms in headwater catchments, Fukushima, Japan

    NASA Astrophysics Data System (ADS)

    Tsujimura, Maki; Onda, Yuichi; Iwagami, Sho; Nishino, Masataka; Konuma, Ryohei

    2014-05-01

    We monitored Cs-137 concentrations in stream water, groundwater, soil water and rainwater in the Yamakiya district located approximately 35 km north west of Fukushima Dai-ichi Nuclear Power Plant (FDNPP) from June 2011 through July 2013, focusing on rainfall-runoff processes during the rainstorm events. Two catchments with different land cover (Iboishiyama and Koutaishiyama) were instrumentd, and stream water, groundwater, soil water and rainwater were sampled for approximately one month at each site, and intensive sampling was conducted during rainstorm events. The 137Cs concentration in stream water showed a relatively quick decreasing trend during 2011. Also, during rainfall events, the Cs-137 concentration in stream water showed a temporary increase. End Member Mixing Analysis was applied to evaluate contribution of groundwater, soil water and rainwater in discharge water during rainstorm events. The groundwater component was dominant in the runoff, whereas rainwater was main source for the Cs-137 concentration of the stream increasing during the storm events. In addition, a leaching of Cs-137 from the suspended sediments and the organic materials seemed to be also important sources to the stream.

  20. Evaluating Hydrologic Responses to Climate Changes in an Inland Pacific Northwest Forested Headwater Catchment by Using Numerical Modeling (Invited)

    NASA Astrophysics Data System (ADS)

    Du, E.; Link, T. E.; Abatzoglou, J. T.

    2010-12-01

    The hydrology of the interior Pacific Northwest (PNW) is dominated by seasonal snowmelt from forested uplands. Hydrologic regimes in the area are vulnerable to climate change as many catchments contain large areas that are located within or above the transient snow zone. Hydrologic regime shifts may result from warmer temperatures that may increase the rain to snow ratio of winter precipitation. This is of concern because as snowpack declines, more runoff occurs earlier in the winter and therefore may increase the interval between the major seasonal runoff and the timing of water resource needs. Warmer temperatures may also increase evaporation and transpiration and extend the seasonal drought in the region. We assessed potential future hydrologic changes in the Mica Creek Experimental Watershed (MCEW), a mountainous headwater catchment in northern Idaho, using data from an ensemble of 12 downscaled general circulation models (GCM) based on the IPCC A1B greenhouse gas emission scenario. The data were used to drive the physically based, spatially explicit Distributed Hydrology Soil Vegetation Model (DHSVM) to estimate future flow regimes. The simulation results indicate that seasonal snowpack in this snow-dominated watershed almost completely disappears by 2046 with corresponding mean annual temperature increases of 2.7-4.7 C and annual precipitation stays almost the same. Compared to the 1981-2000 time period, evaporative fluxes are predicted to increase by 9-63% in 2046-2065, most of which occurs during the winter months. Annual water yield predictions in 2046-2065 range from 55% to 100% of the current value. The streamflow simulations suggest large seasonal flow changes; winter runoff (October-March) increases by 44 to 183%, whereas spring and summer runoff (April -September) declines by 23 to 70%. The simulations suggest that the annual hydrograph centroid is expected to advance by 17 to 73 days, and that seasonal peakflows should decrease and shift from May to

  1. Long term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: Trends, mechanisms and heterogeneity.

    NASA Astrophysics Data System (ADS)

    Oni, Stephen; Futter, Martyn; Bishop, Kevin; Kohler, Stephan; Ottosson-Lofvenius, Mikael; Laudon, Hjalmar

    2013-04-01

    The effects of climate change are currently apparent in the boreal landscape of northern Sweden. Warmer temperature and declining acid deposition are affecting runoff chemistry. These effects are mediated by landscape type. Markedly different responses are observed in streams draining forest and mire landscape elements. Here, we assess long-term water quality time-series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Temporal trends in weather and runoff (1981-2008); dissolved organic carbon concentration [DOC] (1993-2010) and other water quality parameters (1987-2011) were assessed. Historically, sulfate deposition is low in the region and is further declining. There was no significant annual trend in precipitation or runoff but a significant monotonic increasing trend existed in air temperature and length of growing season. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. Water temperature increased significantly both annually and in most months while iron and DOC concentrations showed significant increases in autumn months. Though all streams showed significant positive trends in [DOC] in autumn, only C2 had a significant annual increasing trend. There was also a shift in the magnitude of variability in spring [DOC] and increasing trend of summer baseflow [DOC] in C2 and C7.

  2. Long term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

    NASA Astrophysics Data System (ADS)

    Oni, S. K.; Futter, M. N.; Bishop, K.; Köhler, S. J.; Ottosson-Löfvenius, M.; Laudon, H.

    2012-12-01

    The boreal landscape is a complex, spatio-temporally varying mosaic of forest and mire landscape elements that control surface water hydrology and chemistry. Here, we assess long-term water quality time-series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Temporal trends in weather and runoff (1981-2008); dissolved organic carbon concentration [DOC] (1993-2010) and other water quality parameters (1987-2011) were assessed. There was no significant annual trend in precipitation or runoff but a significant monotonic increasing trend existed in air temperature and length of growing season. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. Water temperature increased significantly both annually and in most months while iron and DOC concentrations showed significant increases in autumn months. Though all streams showed significant positive trends in [DOC] in autumn, only C2 had a significant annual increasing trend. There was also a shift in the magnitude of variability in spring [DOC] and increasing trend of summer baseflow [DOC] in C2 and C7.

  3. Problems with heterogeneity in physically based agricultural catchment models

    NASA Astrophysics Data System (ADS)

    Hansen, Jeppe Rølmer; Refsgaard, Jens Christian; Hansen, Søren; Ernstsen, Vibeke

    2007-08-01

    SummaryLumped conceptual rainfall-runoff models and physically based distributed models are being used successfully for simulating daily discharge at catchment scale. Physically based models are more desirable for simulation of the fate of agrochemicals (e.g. nitrate) because they rely on physical equations for flow and transport. The literature shows that the average response (e.g. percolation and leaching) at field scale can be simulated successfully by using effective or standard values in the parameterisation of these models. However, in areas characterised by a high degree of spatial variability the physically based models sometimes fail to simulate the discharge dynamics at catchment scale properly possibly due to the lack of representation of sub-grid variability. This paper presents an agricultural physically based distributed model concept which included 3561 combinations of root zone simulations of percolation and leaching that was distributed within a 622 km 2 catchment according to land use, climate, soil types, etc. This was thought to account for all heterogeneity within the catchment but did not. It was shown that a much simpler model with less than 100 combinations of root zone calculations partially including important variability at the catchment scale could simulate discharge equally well and in some cases better than the complex one. The most important parameter heterogeneity to include in the conceptualisation step apparently was sub-grid variation of soil physical parameters and variability of crop growth. The variation of crop growth was forced by restricting the rooting depth which potentially lumped other heterogeneities into this property. The results also suggest that the groundwater table that constitutes the lower boundary condition in the unsaturated zone is another important factor. However, this was difficult to examine because of the modelling approach that did not feature feedback from the saturated to the unsaturated zone. A list

  4. Changes in measured spatiotemporal patterns of hydrological response after partial deforestation in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Wiekenkamp, I.; Huisman, J. A.; Bogena, H. R.; Graf, A.; Lin, H. S.; Drüe, C.; Vereecken, H.

    2016-11-01

    Although the hydrological effects of land use change have been studied extensively, only few datasets are available to accurately describe, model, and predict detailed changes in spatiotemporal patterns of hydrological fluxes and states due to land use change. The Wüstebach catchment within the TERENO (TERrestrial Environmental Observatories) network in Germany provides a unique monitoring setup to measure the major components of the water balance (evapotranspiration, discharge, precipitation) and the spatiotemporal distribution of soil moisture before and after a partial deforestation. Here, we present five years of measured hydrological data, including all major water budget components three years before and two years after a partial deforestation. A data-driven approach was used to understand changes and related feedback mechanisms in spatiotemporal hydrological response patterns. As expected from earlier studies, the partial deforestation caused a decrease in evapotranspiration and an increase in discharge. A closer look at the high resolution datasets revealed new insights in the intra-annual variability and relationship between the water balance components. The overall decrease in evapotranspiration caused a large increase in soil water storage in the deforested region, especially during the summer period, which in turn caused an increase in the frequency of high discharge in the same period. Although the evapotranspiration in the forested region was larger on average, the deforested region showed a higher evapotranspiration during part of the summer period. This could be related to wetter conditions in the deforested area, accompanied with the emergence of grass vegetation. At the same time, wetter soil moisture conditions in the deforested area increased the spatial variance of soil moisture in the summer and therewith altered the relationship between spatial mean and variance. Altogether, this study illustrates that detailed spatiotemporal monitoring can

  5. Rainfall-Runoff Dynamics Following Wildfire in Mountainous Headwater Catchments, Alberta, Canada.

    NASA Astrophysics Data System (ADS)

    Williams, C.; Silins, U.; Bladon, K. D.; Martens, A. M.; Wagner, M. J.; Anderson, A.

    2015-12-01

    in these northern Rocky Mountain catchments.

  6. Using continuous monitoring of physical parameters to better estimate phosphorus fluxes in a small agricultural catchment

    NASA Astrophysics Data System (ADS)

    Minaudo, Camille; Dupas, Rémi; Moatar, Florentina; Gascuel-Odoux, Chantal

    2016-04-01

    Phosphorus fluxes in streams are subjected to high temporal variations, questioning the relevance of the monitoring strategies (generally monthly sampling) chosen to assist EU Directives to capture phosphorus fluxes and their variations over time. The objective of this study was to estimate the annual and seasonal P flux uncertainties depending on several monitoring strategies, with varying sampling frequencies, but also taking into account simultaneous and continuous time-series of parameters such as turbidity, conductivity, groundwater level and precipitation. Total Phosphorus (TP), Soluble Reactive Phosphorus (SRP) and Total Suspended Solids (TSS) concentrations were surveyed at a fine temporal frequency between 2007 and 2015 at the outlet of a small agricultural catchment in Brittany (Naizin, 5 km2). Sampling occurred every 3 to 6 days between 2007 and 2012 and daily between 2013 and 2015. Additionally, 61 storms were intensively surveyed (1 sample every 30 minutes) since 2007. Besides, water discharge, turbidity, conductivity, groundwater level and precipitation were monitored on a sub-hourly basis. A strong temporal decoupling between SRP and particulate P (PP) was found (Dupas et al., 2015). The phosphorus-discharge relationships displayed two types of hysteretic patterns (clockwise and counterclockwise). For both cases, time-series of PP and SRP were estimated continuously for the whole period using an empirical model linking P concentrations with the hydrological and physic-chemical variables. The associated errors of the estimated P concentrations were also assessed. These « synthetic » PP and SRP time-series allowed us to discuss the most efficient monitoring strategies, first taking into account different sampling strategies based on Monte Carlo random simulations, and then adding the information from continuous data such as turbidity, conductivity and groundwater depth based on empirical modelling. Dupas et al., (2015, Distinct export dynamics for

  7. Comparing erosion rates in burnt forests and agricultural fields for a mountain catchment in NW Iberia

    NASA Astrophysics Data System (ADS)

    Nunes, João Pedro; Marisa Santos, Juliana; Bernard-Jannin, Léonard; Keizer, Jan Jacob

    2013-04-01

    A large part of northwestern Iberia is nowadays covered by commercial forest plantations of eucalypts and maritime pines, which have partly replaced traditional agricultural land-uses. The humid Mediterranean climate, with mild wet winters and warm dry summers, creates favorable conditions for the occurrence of frequent and recurrent forest fires. Erosion rates in recently burnt areas have been the subject of numerous studies; however, there is still a lack of information on their relevance when compared with agricultural erosion rates, impairing a comprehensive assessment of the role of forests for soil protection. This study focuses on Macieira de Alcoba, head-water catchment in the Caramulo Mountain Range, north-central Portugal, with a mixture of agricultural fields (mostly a rotation between winter pastures and summer cereals) on the lower slopes and forest plantations (mostly eucalypts) on the upper slopes. Agricultural erosion in this catchment has been monitored since 2010; a forest fire in 2011 presented an opportunity to compare post-fire and agricultural erosion rates at nearby sites with comparable soil and climatic conditions. Erosion rates were monitored between 2010 and 2013 by repeated surveys of visible erosion features and, in particular, by mapping and measuring rills and gullies after important rainfall events. During the 2011/2012 hydrological year, erosion rates in the burnt forest were two orders of magnitude above those in agricultural fields, amounting to 17.6 and. 0.1 Mg ha-1, respectively. Rills were widespread in the burnt area, while in the agricultural area they were limited to a small number of fields with higher slope; these particular fields experienced an erosion rate of 2.3 Mg ha-1, still one order of magnitude lower than at the burnt forest site. The timing of the erosion features was also quite distinct for the burnt area and the agricultural fields. During the first nine months after the fire, rill formation was not observed in

  8. Temporal dynamics between cattle in-stream presence and suspended solids in a headwater catchment.

    PubMed

    Terry, Julie A; McW H Benskin, Clare; Eastoe, Emma F; Haygarth, Philip M

    2014-07-01

    Cattle in-stream activity is potentially an important contributor to water pollution from agriculture. Here we present research on the physical movements of cattle within a stream on suspended solid concentrations (SSC). This study used camera surveillance to monitor the in-stream activity of dairy cattle in an unfenced reach over a four-month period. Results were compared against high-resolution SSC data. Over the days that cattle grazed the field, 57.9% of the instances when SSC crossed the 25 mg l(-1) Freshwater Fish Directive guideline threshold can be attributed to cattle presence in the stream. Flow was the main driver of total sediments transported over the study period, and no relationship was found between SSC and the absolute number of cattle feet in the water. Hysteresis analysis indicated a 'first-flush' of local sediments rapidly mobilised during the non-cattle related SSC events, a result of cattle proximity to channel margins. Results demonstrate a temporal lag between cattle in-stream presence and a critical amount of their contribution to sediment load, and that monitoring only instantaneously with cattle activity may lead to underestimation of their pollution impact.

  9. Integrated surface-subsurface model to investigate the role of groundwater in headwater catchment runoff generation: A minimalist approach to parameterisation

    NASA Astrophysics Data System (ADS)

    Ala-aho, Pertti; Soulsby, Chris; Wang, Hailong; Tetzlaff, Doerthe

    2017-04-01

    Understanding the role of groundwater for runoff generation in headwater catchments is a challenge in hydrology, particularly so in data-scarce areas. Fully-integrated surface-subsurface modelling has shown potential in increasing process understanding for runoff generation, but high data requirements and difficulties in model calibration are typically assumed to preclude their use in catchment-scale studies. We used a fully integrated surface-subsurface hydrological simulator to enhance groundwater-related process understanding in a headwater catchment with a rich background in empirical data. To set up the model we used minimal data that could be reasonably expected to exist for any experimental catchment. A novel aspect of our approach was in using simplified model parameterisation and including parameters from all model domains (surface, subsurface, evapotranspiration) in automated model calibration. Calibration aimed not only to improve model fit, but also to test the information content of the observations (streamflow, remotely sensed evapotranspiration, median groundwater level) used in calibration objective functions. We identified sensitive parameters in all model domains (subsurface, surface, evapotranspiration), demonstrating that model calibration should be inclusive of parameters from these different model domains. Incorporating groundwater data in calibration objectives improved the model fit for groundwater levels, but simulations did not reproduce well the remotely sensed evapotranspiration time series even after calibration. Spatially explicit model output improved our understanding of how groundwater functions in maintaining streamflow generation primarily via saturation excess overland flow. Steady groundwater inputs created saturated conditions in the valley bottom riparian peatlands, leading to overland flow even during dry periods. Groundwater on the hillslopes was more dynamic in its response to rainfall, acting to expand the saturated area

  10. Effects of pipeflow on hydrological process and its relation to landslide: a review of pipeflow studies in forested headwater catchments

    NASA Astrophysics Data System (ADS)

    Uchida, Taro; Kosugi, Ken'ichirou; Mizuyama, Takahisa

    2001-08-01

    Since the 1980s, several field studies of pipeflow hydrology have been conducted in forested, steep headwater catchments. However, adequate information is lacking with regard to questions as to how representative these previous studies are and how widespread the phenomena might be. Thus, the aim of this study is to review some studies of pipeflow hydrology on forested steep hillslopes. Several points were clarified. (1) The maximum discharge of pipeflow was mainly determined by the soil pipe diameter. When the condition of both the soil pipe diameter and the slope gradient in forest soil were similar to those in peaty podzol, the maximum discharge of pipeflow on forest slopes was slighter than that in peaty podzol. (2) Pipeflow was delivered from a variety of sources, and the contributing area of pipeflow extended as the soil layer became wetter. Therefore, the dominant contributor (new water and old water) was varied and the contribution of pipeflow to streamflow increased with the increase of rainfall magnitude. (3) The roles of pipeflow in the storm runoff generation processes demonstrated two roles: the concentration of water and the rapid drainage to downslopes. Thus, soil pipes can increase the peak discharge from the hillslope and decrease the peak lag time of the storm hydrograph, when compared to the unpiped hillslope. (4) The roles of pipeflow on hydrological process suggested that the soil pipes contribute to the slope stability by increasing the rate of soil drainage and limiting the development of perched groundwater conditions. However, if the rate of water concentration to the soil pipe network is in excess of the pipeflow transmission capacity, the cavity of the soil pipe could readily be filled with water during a rain event, increasing pore water pressure in the surrounding matrix. In this case, the soil pipe induced slope instability. (5) Moreover, pipe erosion has significant impact on the runoff characteristics of pipeflow, since pipe erosion

  11. Towards an automatic statistical model for seasonal precipitation prediction and its application to Central and South Asian headwater catchments

    NASA Astrophysics Data System (ADS)

    Gerlitz, Lars; Gafurov, Abror; Apel, Heiko; Unger-Sayesteh, Katy; Vorogushyn, Sergiy; Merz, Bruno

    2016-04-01

    Statistical climate forecast applications typically utilize a small set of large scale SST or climate indices, such as ENSO, PDO or AMO as predictor variables. If the predictive skill of these large scale modes is insufficient, specific predictor variables such as customized SST patterns are frequently included. Hence statistically based climate forecast models are either based on a fixed number of climate indices (and thus might not consider important predictor variables) or are highly site specific and barely transferable to other regions. With the aim of developing an operational seasonal forecast model, which is easily transferable to any region in the world, we present a generic data mining approach which automatically selects potential predictors from gridded SST observations and reanalysis derived large scale atmospheric circulation patterns and generates robust statistical relationships with posterior precipitation anomalies for user selected target regions. Potential predictor variables are derived by means of a cellwise correlation analysis of precipitation anomalies with gridded global climate variables under consideration of varying lead times. Significantly correlated grid cells are subsequently aggregated to predictor regions by means of a variability based cluster analysis. Finally for every month and lead time, an individual random forest based forecast model is automatically calibrated and evaluated by means of the preliminary generated predictor variables. The model is exemplarily applied and evaluated for selected headwater catchments in Central and South Asia. Particularly the for winter and spring precipitation (which is associated with westerly disturbances in the entire target domain) the model shows solid results with correlation coefficients up to 0.7, although the variability of precipitation rates is highly underestimated. Likewise for the monsoonal precipitation amounts in the South Asian target areas a certain skill of the model could

  12. Dynamics of stream water TOC concentrations in a boreal headwater catchment: Controlling factors and implications for climate scenarios

    NASA Astrophysics Data System (ADS)

    Köhler, S. J.; Buffam, I.; Seibert, J.; Bishop, K. H.; Laudon, H.

    2009-06-01

    SummaryTwo different but complementary modelling approaches for reproducing the observed dynamics of total organic carbon (TOC) in a boreal stream are presented. One is based on a regression analysis, while the other is based on riparian soil conditions using a convolution of flow and concentration. Both approaches are relatively simple to establish and help to identify gaps in the process understanding of the TOC transport from soils to catchments runoff. The largest part of the temporal variation of stream TOC concentrations (4-46 mg L -1) in a forested headwater stream in the boreal zone in northern Sweden may be described using a four-parameter regression equation that has runoff and transformed air temperature as sole input variables. Runoff is assumed to be a proxy for soil wetness conditions and changing flow pathways which in turn caused most of the stream TOC variation. Temperature explained a significant part of the observed inter-annual variability. Long-term riparian hydrochemistry in soil solutions within 4 m of the stream also captures a surprisingly large part of the observed variation of stream TOC and highlights the importance of riparian soils. The riparian zone was used to reproduce stream TOC with the help of a convolution model based on flow and average riparian chemistry as input variables. There is a significant effect of wetting of the riparian soil that translates into a memory effect for subsequent episodes and thus contributes to controlling stream TOC concentrations. Situations with high flow introduce a large amount of variability into stream water TOC that may be related to memory effects, rapid groundwater fluctuations and other processes not identified so far. Two different climate scenarios for the region based on the IPCC scenarios were applied to the regression equation to test what effect the expected increase in precipitation and temperature and resulting changes in runoff would have on stream TOC concentrations assuming that

  13. Impacts of forest thinning and climate change on transpiration and runoff rates in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Ray, R. L.; Bales, R. C.; Conklin, M. H.

    2013-12-01

    Using a spatially explicit hydro-ecological model, impacts from forest thinning and climate change on snowpack, evapotranspiration (ET) rates, soil moisture storage, and runoff were investigated in Sierra Nevada headwater catchments spanning elevations of 1,500 to 2,000-m. Along this elevation gradient, precipitation changes from rain-dominated to snow-dominated, so precipitation phase will be strongly impacted by increases in temperature. Mixed-conifer forests in the Sierra Nevada near the 2,000-m elevation band also transpire at a high rate relative to upper elevation forests that are more restricted by colder winter temperatures and lower elevation forests that are more restricted by lower summer soil moisture, increasing the potential of reduced transpiration with vegetation thinning. Forest treatment and climate change scenarios were modeled using the Regional Hydro-Ecological Simulation System (RHESSys), calibrated with two years of snow, soil moisture, and streamflow observations. Simulations of forest thinning at moderate (66% of current vegetation density) and restoration (33% density) levels were combined with precipitation changes up to 20% and temperature increases up to 6οC for projecting impacts on ET and runoff rates. Model results indicated that moderate thinning alone could increase runoff by 3%, but additional temperature increases of 2-4οC could increase runoff rates another 6% - similar to a restoration level thinning. Modifying temperature and precipitation separately showed that the two methods of climate forcing both led to fluctuations in soil moisture, caused by changes in precipitation phase (snow/rain) and final day of snowpack melt. The snowmelt timing affected runoff rates by causing changes in the spring soil moisture recession, and showed that it may be one of the critical processes that affects annual runoff rates, not just runoff timing. Simulations of precipitation and temperature changes together showed that precipitation would

  14. Nitrogen loadings and environmental impacts in rice agriculture catchments in subtropical central China

    NASA Astrophysics Data System (ADS)

    Wang, Y.

    2015-12-01

    The severe deterioration of water quality in rice agriculture catchments challenges ecologists and hydrologists in exploring how rice agriculture affects nutrient loadings and water quality. This research observed the nitrogen (N) concentrations in stream water and groundwater in one forest and five rice agriculture catchments in subtropical central China to quantify the relationships between rice agriculture intensification, water quality of water bodies, and catchment N loadings. Our results indicate that intensive rice agriculture deteriorated stream water quality. A non-linear fitting analysis using a Boltzmann sigmoid function suggests that the concentrations and mass fluxes of ammonium-N (NH4+-N), nitrate-N (NO3--N), and total N (TN) in stream water increase with the areal proportion of rice agriculture in the catchments; however, these increases can only be detected when the areal proportions of rice agriculture in the catchments are greater than 13-30%, highlighting the importance of reasonable land use planning for managing stream water quality as well as N loadings from catchments. The factorial correspondence analysis (FCA) also suggests that rice agriculture has a potential to impose groundwater NH4+-N pollution, particularly in the soil exhausting season of July - October. And, the great N fertilizer application rates for rice cropping can increase the groundwater NO3-N and TN concentrations due to large quantities of N leaching into groundwater system beneath the paddy fields. The high N concentrations in groundwater result in strong N loadings via the base flow process. The NO3--N loadings via the base flow reaches 0.12-0.27 kg N ha-1 month-1 in the rice agriculture catchments, contributing 27.3%-36.5% of the total NO3--N loadings by the stream discharge. Therefore, the best management practices for N reduction and the smart land use planning should be applied in the rice agriculture catchments to improve water quality and mitigate N loadings.

  15. Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

    NASA Astrophysics Data System (ADS)

    Thomas, Zahra; Abbott, Benjamin W.; Troccaz, Olivier; Baudry, Jacques; Pinay, Gilles

    2016-03-01

    Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43-) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent

  16. Redox dynamics in the active layer of an Arctic headwater catchment; examining the potential for transfer of dissolved methane from soils to stream water

    NASA Astrophysics Data System (ADS)

    Street, Lorna E.; Dean, Joshua F.; Billett, Michael F.; Baxter, Robert; Dinsmore, Kerry J.; Lessels, Jason S.; Subke, Jens-Arne; Tetzlaff, Doerthe; Wookey, Philip A.

    2016-11-01

    The linkages between methane production, transport, and release from terrestrial and aquatic systems are not well understood, complicating the task of predicting methane emissions. We present novel data examining the potential for the saturated zone of active layer soils to act as a source of dissolved methane to the aquatic system, via soil water discharge, within a headwater catchment of the continuous permafrost zone in Northern Canada. We monitored redox conditions and soil methane concentrations across a transect of soil profiles from midstream to hillslope and compare temporal patterns in methane concentrations in soils to those in the stream. We show that redox conditions in active layer soils become more negative as the thaw season progresses, providing conditions suitable for net methanogenesis and that redox conditions are sensitive to increased precipitation during a storm event—but only in shallower surface soil layers. While we demonstrate that methane concentrations at depth in the hillslope soils increase over the course of the growing season as reducing conditions develop, we find no evidence that this has an influence on stream water methane concentrations. Sediments directly beneath the stream bed, however, remain strongly reducing at depth throughout the thaw season and contain methane at concentrations 5 orders of magnitude greater than those in hillslope soils. The extent of substreambed methane sources, and the rates of methane transport from these zones, may therefore be important factors determining headwater stream methane concentrations under changing Arctic hydrologic regimes.

  17. Forest Harvesting of a Rocky Mountain Headwater Catchment: Assessing the Impacts on Runoff and Sediment Transport Into and Through Riparian Buffers

    NASA Astrophysics Data System (ADS)

    Puntenney, K.; Bladon, K. D.; Silins, U.

    2015-12-01

    Mitigating forest harvesting impacts by retaining a vegetated riparian buffer along headwater streams is a widely implemented best management practice. However, there is still debate over current retention practices and their effectiveness at regulating runoff, erosion, and sediment transport from harvested areas to streams. Forested, headwater catchments on the eastern slopes of the Rocky Mountains (49°37' N, 114°40' W) were harvested in winter 2015. Fixed-width (30 m) riparian buffers were retained based on the regional operating ground rules for all of the identified and mapped hydrologic features. Modified Gerlach troughs (total n=40) were installed along the cutblock-buffer interface, 10 m into the vegetated buffer, and in unharvested control sites to collect runoff and sediment. Site characteristics, including surface soil moisture, slope, vegetation cover, soil type, litter depth, and upslope accumulated area will be used to describe differences in runoff volumes and sediment concentrations between sites. Rainfall simulations are also being used to quantify and compare the initiation of runoff, runoff volumes, and sediment concentrations under high intensity precipitation events in cutblocks, at the cutblock-buffer interface, and within vegetated buffers. Broad objectives of this ongoing study are to identify spatio-temporal hotspots of runoff and sediment transport from cutblocks into and through riparian buffers.

  18. Predicting runoff-induced pesticide input in agricultural sub-catchment surface waters: linking catchment variables and contamination.

    PubMed

    Dabrowski, James M; Peall, Sue K C; Van Niekerk, Adriaan; Reinecke, Adriaan J; Day, Jenny A; Schulz, Ralf

    2002-12-01

    An urgent need exists for applicable methods to predict areas at risk of pesticide contamination within agricultural catchments. As such, an attempt was made to predict and validate contamination in nine separate sub-catchments of the Lourens River, South Africa, through use of a geographic information system (GIS)-based runoff model, which incorporates geographical catchment variables and physicochemical characteristics of applied pesticides. We compared the results of the prediction with measured contamination in water and suspended sediment samples collected during runoff conditions in tributaries discharging these sub-catchments. The most common insecticides applied and detected in the catchment over a 3-year sampling period were azinphos-methyl (AZP), chlorpyrifos (CPF) and endosulfan (END). AZP was predominantly found in water samples, while CPF and END were detected at higher levels in the suspended particle samples. We found positive (p < 0.002) correlations between the predicted average loss and the concentrations of the three insecticides both in water and suspended sediments (r between 0.87 and 0.94). Two sites in the sub-catchment were identified as posing the greatest risk to the Lourens River mainstream. It is assumed that lack of buffer strips, presence of erosion rills and high slopes are the main variables responsible for the high contamination at these sites. We conclude that this approach to predict runoff-related surface water contamination may serve as a powerful tool for risk assessment and management in South African orchard areas.

  19. Influence of riparian seepage zones on nitrate variability in two agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian seepage zones are one of the primary pathways of groundwater transport to headwater streams. While seeps have been recognized for their contributions to streamflow, there is little information on how seeps affect stream water quality. The objective of this study was to examine the influence...

  20. Informing Hydrological Drought Response in Headwater Catchments Using Water Storage Estimated From GRACE: Storage-Flow Dynamics

    NASA Astrophysics Data System (ADS)

    Gaffney, R.; Tyler, S. W.; Harpold, A. A.; Volk, J. M.

    2015-12-01

    Quantifying the relationship between subsurface water storage and streamflow is challenging due to heterogeneity of surface-groundwater interactions in space and time. Hence, point measurements of storage from wells are insufficient to characterize the storage across a catchment, especially in mountainous environments with complex geology. Here, we present a novel approach to quantify the storage-flow relationship for catchments in the Sierra Nevada Mountains. For 23 gages in the Hydro-Climatic Data Network, the 7-day average annual minimum flow (drought flow) was computed for years 2003 to 2015. We then aggregated, for each gage, the associated storage time-series dataset from 1o gridded measurements of monthly Terrestrial Water Storage (TWS) derived from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. Despite the significant mismatch between the spatial scales and temporal resolution, we found a strong empirical correlation between TWS and drought flow. From these relationships, we examined how physical characteristics of each catchment (such as size and geology) impact the observed nonlinear relationship between TWS and drought flow. Furthermore, we show how physical characteristics, such as geology/storage capacity, of catchments affect the sensitivity of decreasing flows to multi-year droughts. This research has the potential to help better quantify the streamflow-storage relationship in small mountainous catchments, as well as, classify catchments that may be more vulnerable to decreasing flows with multi-year droughts.

  1. Responses of Emergent Behaviour in Headwater Catchments to Long-term and Short-term Environmental Change

    NASA Astrophysics Data System (ADS)

    Tetzlaff, D.; Soulsby, C.; Malcolm, I. A.; Brewer, M. J.

    2007-12-01

    Emergent behaviour of hydrological processes at the catchment scale often results in relatively simple and predictable functional characteristics which are underpinned by heterogeneous, complex processes at the small scale. It is unclear how such small-scale processes are affected by long- and short-term perturbations in forcing factors affected by various environmental changes. This leads to uncertainty in how emergent behaviour will change and how hydrology and hydrochemistry will respond at the catchment scale. A powerful resource in improving predictions of such responses is applying advanced statistical analysis to long-term data sets of conservative tracers, particularly in gauged catchments that are subject to marked environmental change. Changes in tracer behaviour can provide an integrated insight into the emergent response of system functioning and its non-linear characteristics. In this paper, we present the analysis of long-term tracer data collected since 1982 in 2 small (ca. 1km2) experimental catchments in the Scottish highlands. These have been affected by marked change and variability in driving variables of climate, land cover and rainfall chemistry: Annual rainfall ranged between 1490 and 2500mm and an average 1°C increase in air temperatures was observed over the monitoring period. In addition, forestry operations resulted in 70% of each catchment being clear felled. Finally, air pollution legislation targeting acid emissions has improved the quality of precipitation, resulting in a marked reduction in acid deposition. Long-term (20 year, weekly) time-series analyses of two tracers are used to assess changes in emergent catchment behaviour. Chloride input-output time series are analysed using a range of residence time models which highlighted non-stationarity in the catchment mean residence times (which ranged between 2-11 months for individual years) and corresponding residence time distributions. At the catchments scale these were driven

  2. Effects of Catchment Characteristics and Disturbances on Storage and Export of Dissolved Organic Carbon in a Boreal Headwater Stream

    NASA Astrophysics Data System (ADS)

    Hillman, G. R.; Feng, J. C.; Feng, C. C.; Wang, Y.

    2004-05-01

    The transportation of large amounts of dissolved organic carbon (DOC) down a stream within a 15.51-km2 catchment in Alberta, Canada, related directly to events, such as high rainfall and beaver dam failures, that created major disturbances. A 2.3-km section of the stream was drastically altered in June 1994 when a flood wave resulting from a breached beaver dam deposited large amounts of debris and sediment within the section. Results from stream DOC storage analyses, in which a difference method was used, suggest that the organic debris dams created by the failed dam event served as both sources and sinks for DOC. Discharge and DOC measurements at hydrometric stations located at intervals along the stream indicated that storage of DOC in the stream was strongly influenced by the presence of wetlands and beaver (Castor canadensis). Disturbances occurring during periods totalling 28 days in 1994 and 17 days in 1995 accounted for 94% (1374 kg u km-2) and 84% (204 kg u km-2), respectively, of the amount of DOC exported from the catchment during the May-September period. DOC concentrations in the stream were greatest (77.0 mgL-1) near the top of the catchment where a 2-km2 fen served as the primary source of DOC. Stream DOC concentrations decreased progressively downstream to the catchment outlet where the mean concentration was 23.3 mgL-1.

  3. LANDSCAPE INFLUENCES ON IN-STREAM BIOTIC INTEGRITY: USE OF MACROINVERTEBRATE METRICS TO IDENTIFY LANDSCAPE STRESSORS IN HEADWATER CATCHMENTS

    EPA Science Inventory

    The biotic integrity of streams is profoundly influenced by quantitative and qualitative features in the landscape of the surrounding catchment. In this study, aquatic macroinvertebrate metrics (e.g., relative abundance of Ephemeroptera, Trichoptera, and/or Plecoptera taxa, or t...

  4. Contribution of radioactive (137)Cs discharge by suspended sediment, coarse organic matter, and dissolved fraction from a headwater catchment in Fukushima after the Fukushima Dai-ichi Nuclear Power Plant accident.

    PubMed

    Iwagami, Sho; Onda, Yuichi; Tsujimura, Maki; Abe, Yutaka

    2017-01-01

    Radiocesium ((137)Cs) migration from headwaters in forested areas provides important information, as the output from forest streams subsequently enters various land-use areas and downstream rivers. Thus, it is important to determine the composition of (137)Cs fluxes (dissolved fraction, suspended sediment, or coarse organic matter) that migrate through a headwater stream. In this study, the (137)Cs discharge by suspended sediment and coarse organic matter from a forest headwater catchment was monitored. The (137)Cs concentrations in suspended sediment and coarse organic matter, such as leaves and branches, and the amounts of suspended sediment and coarse organic matter were measured at stream sites in three headwater catchments in Yamakiya District, located ∼35 km northwest of Fukushima Dai-ichi Nuclear Power Plant (FDNPP) from August 2012 to September 2013, following the earthquake and tsunami disaster. Suspended sediment and coarse organic matter were sampled at intervals of approximately 1-2 months. The (137)Cs concentrations of suspended sediment and coarse organic matter were 2.4-49 kBq/kg and 0.85-14 kBq/kg, respectively. The (137)Cs concentrations of the suspended sediment were closely correlated with the average deposition density of the catchment. The annual proportions of contribution of (137)Cs discharge by suspended sediment, coarse organic matter, and dissolved fraction were 96-99%, 0.0092-0.069%, and 0.73-3.7%, respectively. The total annual (137)Cs discharge from the catchment was 0.02-0.3% of the deposition.

  5. Hydrologic monitoring in 1-km2 headwater catchments in Sierra Nevada forests for predictive modeling of hydrologic response to forest treatments across 140-km2 firesheds

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Conklin, M. H.; Martin, S. E.; Rice, R.

    2010-12-01

    As part of the Sierra Nevada Adaptive Management Project, an eight-year study designed to measure the impacts of forest treatments (thinning, mastication, controlled burns) on multiple forest attributes, four headwater catchments were established to provide data on hydrologic response to treatments. These 1-km2 study catchments are each sited within 40-100 km2 firesheds, which in this case largely follow watershed boundaries, and which are the larger study areas for informing adaptive management of approximately 3,000 km2 of mixed-conifer forest in California’s central and southern Sierra Nevada. The aim of the hydrologic design was to put in place a ground-based monitoring network that would measure hydrologic attributes at representative locations, and when combined with remotely sensed data, provide a basis for predictive modeling of the larger study area. The selected locations employ instrument clusters, or groupings of instruments in a compact arrangement, to maximize the number of measurements possible and accessibility to the monitoring sites. The two study firesheds , located in the Tahoe and Sierra National Forests, cover a total of about 140-km2. Within each fireshed, two meteorological stations were placed near 1650-m and 2150-m, spanning the precipitation gradient from lower-elevation rain-dominated to higher-elevation snow-dominated systems. Two headwater streams draining approximately 1-km2 are monitored for stage, discharge, electrical conductivity, and sediment movement. Additionally, instrument nodes to monitor temperature, snow depth and soil moisture are installed within 0.5-1 km of the outlet and meterological stations. These nodes were placed to monitor end members of aspect, slope, elevation and canopy cover, which set the boundaries for the model outputs. High-resolution LiDAR provides the topographic and distributed vegetation characteristics, which are combined with field surveys and standard soils information to define the modeling

  6. Watershed scale influence of pesticide reduction practices on pesticides and fishes within channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Implementation of pesticide reduction practices to reduce pesticide usage within agricultural watersheds has the potential to reduce pesticide concentrations within agricultural streams. The watershed scale influence of pesticide reduction practices on pesticides and the biota within agricultural he...

  7. Effects of exposure to agricultural drainage ditch water on survivorship, distribution, and abundnance of riffle beetles (Coleoptera: Elmidae) in headwater streams of the Cedar Creek watershed, Indiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riffle Beetles (Coleoptera: Elmidae) require very good water quality, mature streams with riffle habitat, and high dissolved oxygen content. As such, they prove to be good indicators of ecological health in agricultural headwater streams. We conducted static renewal aquatic bioassays using water fro...

  8. Inferring runoff generation processes through high resolution spatial and temporal UV-Vis absorbance measurements in a mountainous headwater catchment in Southern Ecuador

    NASA Astrophysics Data System (ADS)

    Windhorst, David; Schob, Sarah; Zang, Carina; Crespo, Patricio; Breuer, Lutz

    2015-04-01

    The alpine grassland páramo - typically occurring in the headwater catchments of the Andes - plays an important role in flow regulation, hydropower generation and local water supply. However, hydrological and hydro-biogeochemical processes in the páramo and their potential reactions to climate and land use change are largely unknown. Therefore, we used a UV-Vis absorbance spectrometer to investigate fluxes of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity and nitrate (NO3-N) in a small headwater catchment (91.31 km²) in the páramo in south Ecuador on a 5 min temporal and 100 m spatial resolution to gain first insights in its hydrological functioning. Spatial sampling was realized during three snapshot sampling campaigns along the 14.2 km long stream between October 2013 and January 2014, while temporal sampling took place at a permanent sampling site within the catchment between February and June 2014. To identify the runoff generation processes the spatial patterns have been associated with local site specific (e.g. fish ponds) and sub-catchment wide (e.g. land use) characteristics. Storm flow events within the time series allowed to further study temporal changes and rotational patterns of concentration-discharge relations (hysteresis). In total, 35 events were identified to be suitable for analyzing hysteresis effects of BOD, COD, and turbidity. Nitrate concentrations could be studied for 20 events. Regardless of the flow conditions nitrate leaching increased with a growing share of non-native pine forests or pastures in the study area. During low flow conditions, the high water holding capacity of the upstream páramo areas ensured a continuous supply of BOD to the stream. Pasture and pine forest sites, mostly occurring in the downstream section of the stream, contributed to BOD only during discharge events. Contradicting the expectations the trout farms along the lower part of the streams had a relatively closed nutrient cycle and

  9. Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

    NASA Astrophysics Data System (ADS)

    Oni, S. K.; Futter, M. N.; Bishop, K.; Köhler, S. J.; Ottosson-Löfvenius, M.; Laudon, H.

    2013-04-01

    The boreal landscape is a complex, spatio-temporally varying mosaic of forest and mire landscape elements that control surface water hydrology and chemistry. Here, we assess long-term water quality time series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Acid deposition in this region is low and is further declining. Temporal trends in weather and runoff (1981-2008), dissolved organic carbon concentration [DOC] (1993-2010) and other water quality parameters (1987-2011) were assessed. There was no significant annual trend in precipitation or runoff. However, runoff increased in March and declined in May. This suggested an earlier snowmelt regime in recent years. Significant monotonic increasing trends in air temperature and length of growing season suggested a decrease in snowfall and less spring runoff. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. These results indicate subtle effects of recovery from acidification. Water temperature increased significantly both annually and in most months. A simultaneous monotonic increase in iron (Fe) and [DOC] in autumn suggests co-transport of Fe-DOC in the form of organometallic complexes. A monotonic increase in UV absorbance in most months without co-occurring changes in DOC trend suggests a shift in DOC quality to a more humic-rich type. The observed increase in soil solution [DOC] and subtle trends in stream [DOC] suggest that climate rather than recovery from

  10. Predicting rapid herbicide leaching to surface waters from an artificially drained headwater catchment using a one dimensional two-domain model coupled with a simple groundwater model.

    PubMed

    Tediosi, A; Whelan, M J; Rushton, K R; Gandolfi, C

    2013-02-01

    Pesticide losses to water can present problems for environmental management, particularly in catchments where surface waters are abstracted for drinking water supply. The relative role of different transfer pathways (spray drift, spills, overland flow and leaching from soils) is often uncertain, and there is a need for experimental observation and modelling to ensure that processes are understood under a range of conditions. Here we examine the transport of propyzamide and carbetamide in a small (15.5 ha) headwater sub-catchment dominated by an artificially drained field with strongly undulating topography (topographic gradients >1:10). Specifically, we explore the validity of the "field-scale lysimeter" analogy by applying the one dimensional mathematical model MACRO. Although one dimensional representation has been shown to be reasonable elsewhere, the scale and topography of the monitored system challenge many of the underlying assumptions. MACRO considers two interacting flow domains: micropores and macropores. The effect of subsurface drains can also be included. A component of the outflow from the main drain was identified as originating from an upslope permeable shallow aquifer which was represented using a simple groundwater model. Predicted herbicide losses were sensitive to drain spacing and the organic carbon to water partition coefficient, K(OC). The magnitude of the peak water and herbicide transport and their timing were simulated satisfactorily, although model performance was poor following a period of one month when snow covered the ground and precipitation was underestimated by the rain gauge. Total herbicide loads were simulated adequately by MACRO, suggesting that the field-scale lysimeter analogy is valid at this scale, although baseflow contributions to flow needed to be accounted for separately in order to adequately represent hydrological response.

  11. Projected stream water fluxes of NO3 and total organic carbon from the Storgama headwater catchment, Norway, under climate change and reduced acid deposition.

    PubMed

    de Wit, Heleen A; Wright, Richard F

    2008-02-01

    Fluctuations in the 20-year record of nitrate (NO3) and total organic carbon (TOC) concentrations and fluxes in runoff at the small headwater catchment Storgama, southern Norway, were related to climate and acid deposition. The long-term decline in NO3 related to reduced NO3 deposition and increased winter discharge, whereas the long-term increase in TOC related to reduced sulfur deposition. Multiple regression models describing long-term trends and seasonal variability in these records were used to project future concentrations given scenarios of climate change and acid deposition. All scenarios indicated reduced NO3 fluxes and increased TOC fluxes; the largest projected changes for the period 2071-2100 were -86% and +24%, respectively. Uncertainties are that the predicted future temperatures are considerably higher than the historical record. Also, nonlinear responses of ecosystem processes (nitrogen [N] mineralization) to temperature, N-enrichment of soils, and step-changes in environmental conditions may affect future leaching of carbon and N.

  12. [Contribution of Base Flow to Total Nitrogen Loading in Subtropical Agricultural Catchments].

    PubMed

    Ma, Qiu-mei; Li, Wei; Wang, Yi; Liu, Xin-liang; Li, Yong; Wu, Jin-shui

    2016-04-15

    With the fast development of economics and improvement of people's living standard, non-point source pollution of the agricultural catchments in subtropical China has become more and more severe, where water quality deterioration has become a main barrier for sustainable development and ecological restoration. The process of ecohydrology in catchment is greatly influenced by the process of base flow in channel. This study selected the Tuojia and Jianshan catchments located in Changsha County, Hunan Province, to quantify and compare the contribution of base flow to total nitrogen (TN) loading from January 2011 to December 2013, through field observation and model estimation. The results suggested that the Tuojia catchment with higher intensity of rice agriculture had the greater volume of base flow, higher average flow-weighted TN concentration in base flow, and greater monthly TN loading via base flow [15.2 mm · month⁻¹, 4.14 mg · L⁻¹ and 0.54 kg · (hm² · month)⁻¹, respectively] than those in the Jianshan catchment with lower intensity [11.4 mm · month⁻¹, 1.72 mg · L⁻¹ and 0.20 kg · (hm² · month)⁻¹, respectively]. The base flow contribution to TN loading showed an apparently seasonal pattern. During rice-growing seasons, the contributions of base flow to TN loading were 23.2% and 18.6% in the Tuojia and Jianshan catchments, respectively, lower than those in the fallow seasons (46.9% and 40.0% correspondingly. These results suggested that rice agriculture increased the contribution of base flow in the fallow season to TN loading. Therefore, to alleviate the suffering of non-point source pollution in the rice agriculture catchments, reasonable management measure of rice fields should be implemented to decrease contrihution of base flow to TN loading.

  13. Woo Lecture: Where Does Water Go When it Rains? Conceptualizing Runoff Processes in Headwater Catchments "The Woo Way"

    NASA Astrophysics Data System (ADS)

    McDonnell, J.

    2009-05-01

    Streamflow generation concepts have remained largely unchanged since the First International Hydrological Decade (1965-1974) despite numerous case studies from an ever-widening array of catchments. Two broad classes of streamflow generation behavior have been described and conceptualized into widely used model structures: infiltration excess overland flow and saturation excess overland flow. These concepts rely on the description of spatial patterns of soil surface infiltration rates and "variable source areas" of saturation (from rising near-stream water tables) with known boundary conditions. While subsurface flow during storm events occurs (and in steep wet areas may greatly exceed overland flow contributions), its location and behavior are poorly conceptualized and predicted. The mechanisms of subsurface flow delivery to the stream are seemingly endless and range from lateral preferential flow, to flow along impeding layers, to flow in highly conductive soil and sub-soil layersall largely unpredictable from conditions at the soil surface. So how can we conceptualize subsurface flow and its many manifestations and such poorly known boundary conditions? Can we simplify the myriad subsurface response mechanisms to be consistent with infiltration excess and saturation excess overland flow concepts? This talk examines the future of runoff conceptualization and advances a simple concept of subsurface "storage excess" consistent with the work of MK Woo and his former students (C. Spence and others). I offer evidence in support of storage excess using field data from catchments distributed across a wide array of climate, geology, vegetation and topographic conditions. These data show subsurface storage filling and then spilling is a simple concept that makes sense across many scales and may help explain runoff amount and timing, geographic and time source components, and residence time. I address how such measures might be used for "gauging" the ungauged catchment as

  14. Where does water go when it rains? Conceptualizing runoff processes in headwater catchments (John Dalton Medal Lecture)

    NASA Astrophysics Data System (ADS)

    McDonnell, J.

    2009-04-01

    Streamflow generation concepts have remained largely unchanged since the First International Hydrological Decade (1965-1974) despite numerous case studies from an ever-widening array of catchments. Two broad classes of streamflow generation behavior have been described and conceptualized into widely used model structures: infiltration excess overland flow and saturation excess overland flow. These concepts rely on the description of spatial patterns of soil surface infiltration rates and "variable source areas" of saturation (from rising near-stream water tables) with known boundary conditions. While subsurface flow during storm events occurs (and in steep wet areas may greatly exceed overland flow contributions), its location and behavior are poorly conceptualized and predicted. The mechanisms of subsurface flow delivery to the stream are seemingly endless and range from lateral preferential flow, to flow along impeding layers, to flow in highly conductive soil and sub-soil layers—all largely unpredictable from conditions at the soil surface. So how can we conceptualize subsurface flow and its many manifestations and such poorly known boundary conditions? Can we simplify the myriad subsurface response mechanisms to be consistent with infiltration excess and saturation excess overland flow concepts? This talk examines the future of runoff conceptualization and advances a simple concept of subsurface "storage excess". I offer evidence in support of storage excess using field data from catchments distributed across a wide array of climate, geology, vegetation and topographic conditions. These data show subsurface storage filling and then spilling is a simple concept that makes sense across many scales and may help explain runoff amount and timing, geographic and time source components, and residence time. I address how such measures might be used for "gauging" the ungauged catchment as part of the IAHS Decade on Prediction in Ungauged Basins (2003-2012) and

  15. Soil moisture mapping in torrential headwater catchments using a local interpolation method (Draix-Bléone field observatory, South Alps, France)

    NASA Astrophysics Data System (ADS)

    Mallet, Florian; Marc, Vincent; Douvinet, Johnny; Rossello, Philippe; Le Bouteiller, Caroline; Malet, Jean-Philippe

    2016-04-01

    , soil type or land use. Eventually, the model gives insight into a catchment scale distributed high frequency soil moisture dynamics. This analysis is also used to identify the relative impacts of the morphological determinants on soil moisture content. References : McDonnell, J.J. and K. Beven, 2014. The future of hydrological science: A (common) path forward ? A call to action aimed at understanding velocities, celerities and residence time distributions of the headwater hydrograph. Water Resources Research, 50, 5342-5350. Davies A. C. Davies and K. Beven, 2015. Hysteresis and scale in catchment storage, flow and transport. Hydrological Processes, Volume 29, Issue 16 : 3604-3615. Joly D., Brossard T., Cardot H., Cavailhes J., Hilal M., Wavresky P., 2008. Interpolation par recherche d'information locale. Climatologie, Volume 5 : 27-47.

  16. Restoring the hydrologic response to pre-developed conditions in an urbanized headwater catchment: Reality or utopia?

    NASA Astrophysics Data System (ADS)

    Wright, O.; Istanbulluoglu, E.

    2012-12-01

    The conversion of forested areas to impervious surfaces, lawns and pastures alters the natural hydrology of an area by increasing the flashiness of stormwater generated runoff, resulting in increased streamflow peaks and volumes. Currently, most of the stormwater from developed areas in the Puget Sound region remains uncontrolled. The lack of adequate stormwater facilities along with increasing urbanization and population growth illustrates the importance of understanding urban watershed behavior and best management practices (BMPs) that improve changes in hydrology. In this study, we developed a lumped urban ecohydrology model that represents vegetation dynamics, connects pervious and impervious surfaces and implements various BMP scenarios. The model is implemented in an urban headwater subcatchment located in the Newaukum Creek Basin. We evaluate the hydrologic impact of controlling runoff at the source and disconnecting impervious surfaces from the storm drain using rain barrels and bioretention cells. BMP scenarios consider the basin's land use/land coverage, the response of different impervious surface types, the potential for BMP placement, the size and drainage area for BMPs, and the mitigation needs to meet in-stream flow goals.

  17. Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    NASA Astrophysics Data System (ADS)

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

    2016-04-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

  18. Effect of land use and hydrological processes on Escherichia coli concentrations in streams of tropical, humid headwater catchments.

    PubMed

    Rochelle-Newall, Emma J; Ribolzi, Olivier; Viguier, Marion; Thammahacksa, Chanthamousone; Silvera, Norbert; Latsachack, Keooudone; Dinh, Rinh Pham; Naporn, Piyapong; Sy, Hai Tran; Soulileuth, Bounsamay; Hmaimum, Nikom; Sisouvanh, Pem; Robain, Henri; Janeau, Jean-Louis; Valentin, Christian; Boithias, Laurie; Pierret, Alain

    2016-09-08

    Lack of access to clean water and adequate sanitation continues to be a major brake on development. Here we present the results of a 12-month investigation into the dynamics of Escherichia coli, a commonly used indicator of faecal contamination in water supplies, in three small, rural catchments in Laos, Thailand and Vietnam. We show that land use and hydrology are major controlling factors of E. coli concentrations in streamwater and that the relative importance of these two factors varies between the dry and wet seasons. In all three catchments, the highest concentrations were observed during the wet season when storm events and overland flow were highest. However, smaller peaks of E. coli concentration were also observed during the dry season. These latter correspond to periods of intense farming activities and small, episodic rain events. Furthermore, vegetation type, through land use and soil surface crusting, combined with mammalian presence play an important role in determining E. coli loads in the streams. Finally, sampling during stormflow revealed the importance of having appropriate sampling protocols if information on maximum contamination levels is required as grab sampling at a fixed time step may miss important peaks in E. coli numbers.

  19. Effect of land use and hydrological processes on Escherichia coli concentrations in streams of tropical, humid headwater catchments

    NASA Astrophysics Data System (ADS)

    Rochelle-Newall, Emma J.; Ribolzi, Olivier; Viguier, Marion; Thammahacksa, Chanthamousone; Silvera, Norbert; Latsachack, Keooudone; Dinh, Rinh Pham; Naporn, Piyapong; Sy, Hai Tran; Soulileuth, Bounsamay; Hmaimum, Nikom; Sisouvanh, Pem; Robain, Henri; Janeau, Jean-Louis; Valentin, Christian; Boithias, Laurie; Pierret, Alain

    2016-09-01

    Lack of access to clean water and adequate sanitation continues to be a major brake on development. Here we present the results of a 12-month investigation into the dynamics of Escherichia coli, a commonly used indicator of faecal contamination in water supplies, in three small, rural catchments in Laos, Thailand and Vietnam. We show that land use and hydrology are major controlling factors of E. coli concentrations in streamwater and that the relative importance of these two factors varies between the dry and wet seasons. In all three catchments, the highest concentrations were observed during the wet season when storm events and overland flow were highest. However, smaller peaks of E. coli concentration were also observed during the dry season. These latter correspond to periods of intense farming activities and small, episodic rain events. Furthermore, vegetation type, through land use and soil surface crusting, combined with mammalian presence play an important role in determining E. coli loads in the streams. Finally, sampling during stormflow revealed the importance of having appropriate sampling protocols if information on maximum contamination levels is required as grab sampling at a fixed time step may miss important peaks in E. coli numbers.

  20. Effect of land use and hydrological processes on Escherichia coli concentrations in streams of tropical, humid headwater catchments

    PubMed Central

    Rochelle-Newall, Emma J.; Ribolzi, Olivier; Viguier, Marion; Thammahacksa, Chanthamousone; Silvera, Norbert; Latsachack, Keooudone; Dinh, Rinh Pham; Naporn, Piyapong; Sy, Hai Tran; Soulileuth, Bounsamay; Hmaimum, Nikom; Sisouvanh, Pem; Robain, Henri; Janeau, Jean-Louis; Valentin, Christian; Boithias, Laurie; Pierret, Alain

    2016-01-01

    Lack of access to clean water and adequate sanitation continues to be a major brake on development. Here we present the results of a 12-month investigation into the dynamics of Escherichia coli, a commonly used indicator of faecal contamination in water supplies, in three small, rural catchments in Laos, Thailand and Vietnam. We show that land use and hydrology are major controlling factors of E. coli concentrations in streamwater and that the relative importance of these two factors varies between the dry and wet seasons. In all three catchments, the highest concentrations were observed during the wet season when storm events and overland flow were highest. However, smaller peaks of E. coli concentration were also observed during the dry season. These latter correspond to periods of intense farming activities and small, episodic rain events. Furthermore, vegetation type, through land use and soil surface crusting, combined with mammalian presence play an important role in determining E. coli loads in the streams. Finally, sampling during stormflow revealed the importance of having appropriate sampling protocols if information on maximum contamination levels is required as grab sampling at a fixed time step may miss important peaks in E. coli numbers. PMID:27604854

  1. Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments

    NASA Astrophysics Data System (ADS)

    Graeber, D.; Goyenola, G.; Meerhoff, M.; Zwirnmann, E.; Ovesen, N. B.; Glendell, M.; Gelbrecht, J.; Teixeira de Mello, F.; Gonzalez-Bergonzoni, I.; Jeppesen, E.; Kronvang, B.

    2015-05-01

    Dissolved organic matter (DOM) is an important factor in aquatic ecosystems, which is involved in a large variety of biogeochemical and ecological processes, and recent literature suggests that it could be strongly affected by agriculture in different climates. Based on novel monitoring techniques, we investigated the interaction of climate and agriculture effects on DOM quantity and quality. To examine this, we took water samples over 2 years in two paired intensive and extensive farming catchments in each of Denmark (temperate climate) and Uruguay (subtropical climate). We measured dissolved organic carbon (DOC) and nitrogen (DON) concentrations and DOC and DON molecular fractions with size-exclusion chromatography. Moreover, we characterized DOM quality with absorbance and fluorescence measurements, as well as parallel factor analysis (PARAFAC). We also calculated the DOC and DON loads based on daily discharge measurements, as well as measured precipitation and air temperature. The fluvial DOM in the catchments in Uruguay was characterized by higher temporal variability of DOC and DON loads which were clearly to a higher temporal variability of precipitation and a DOM composition with rather plant-like character relative to the Danish catchments. Moreover, we found a consistently higher temporal variability of DOC and DON loads in the intensive farming catchments than in the extensive farming catchments, with highest temporal variability in the Uruguayan intensive farming catchment. Furthermore, the composition of DOM exported from the intensive farming catchments was consistently complex and always related to microbial processing in both Denmark and Uruguay. This was indicated by low C : N ratios, several spectroscopic DOM composition indices and PARAFAC fluorescence components. We propose that the consistent effect of intensive farming on DOM composition and the temporal variability of DOC and DON loads is related to similarities in the management of

  2. Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments

    NASA Astrophysics Data System (ADS)

    Graeber, D.; Goyenola, G.; Meerhoff, M.; Zwirnmann, E.; Ovesen, N. B.; Glendell, M.; Gelbrecht, J.; Teixeira de Mello, F.; González-Bergonzoni, I.; Jeppesen, E.; Kronvang, B.

    2015-01-01

    Dissolved organic matter (DOM) is an important factor in aquatic ecosystems, which is involved in a large variety of biogeochemical and ecological processes and recent literature suggests that it could be strongly affected by agriculture in different climates. Based on novel monitoring techniques, we investigated the interaction of climate and agriculture effects on DOM quantity and molecular composition. To examine this, we took water samples over two years in two paired intensive and extensive farming catchments in each Denmark (temperate climate) and Uruguay (subtropical climate). We measured dissolved organic carbon (DOC) and nitrogen (DON) concentrations and DOC and DON molecular fractions with size-exclusion chromatography. Moreover, we assessed DOM composition with absorbance and fluorescence measurements, as well as parallel factor analysis (PARAFAC). We also calculated DOC and DON loads based on daily discharge measurements, as well as measured precipitation and air temperature. In the catchments in Uruguay, the fluvial DOM was characterized by higher temporal variability of DOC and DON loads which were clearly related to a higher temporal variability of precipitation and a DOM composition with rather plant-like character relative to the Danish catchments. Moreover, we consistently found a higher temporal variability of DOC an DON loads in the intensive farming catchments than in the extensive farming catchments, with the highest temporal variability in the Uruguayan intensive farming catchment. Moreover, the composition of DOM exported from the intensive farming catchments was always complex and related to microbial processing in both Denmark and Uruguay. This was indicated by low C : N ratios, several spectroscopic DOM composition indexes and the PARAFAC fluorescence components. We propose that the consistent effect of intensive farming on DOM composition and the temporal variability of DOC and DON loads is related to similarities in the management of

  3. Quantifying faecal indicator organism hydrological transfer pathways and phases in agricultural catchments.

    PubMed

    Murphy, S; Jordan, P; Mellander, P-E; O' Flaherty, V

    2015-07-01

    Faecal indicator organisms (FIOs) can impact on water quality and pose a health and environmental risk. The transfer of FIOs, such as Escherichia coli (E. coli), from land to water is driven by hydrological connectivity and may follow the same flowpaths as nutrients, from agricultural and human sources. This study investigated E. coli transfer in two catchment areas with high source and transport pressures. These pressures were: organic phosphorus (P) loading; human settlement; conduits and fissures in a grassland karst area; and clay rich and impermeable soils in a mixed arable area. The occurrence of E. coli and its transport pathways, along with the pathways of nutrients, were studied using a combination of targeted FIO sampling, during different hydrological phases and events, and high resolution nutrient analysis. The quick flow component in both catchments was found to be a more potent vector for E. coli, and was coincident with the total P flowpaths using a P Loadograph Recession Analysis (LRA). The karst grassland catchment was found to be a transport limited system and the mixed arable catchment a source limited system. Hence, despite the grassland catchment being a potentially higher FIO source, the E. coli loads leaving the catchment were low compared to the mixed arable catchment. E. coli load whole-event comparisons also indicated that the grassland karst transfers tended to be much lower on falling phases of runoff, while the arable catchment, over greywacke and mudstone geology, showed little change between the phases. Furthermore, the arable catchment showed asymptotic decline of sustained E. coli loads towards low flows, which may be indicative of chronic point sources. These results indicate the dominance of transport mechanisms over source mechanisms for mass E. coli loads and also chronic loads during low flow. These will be important considerations for risk assessment and mitigation.

  4. Identifying critical source areas for water quality: 1. Mapping and validating transport areas in three headwater catchments in Otago, New Zealand

    NASA Astrophysics Data System (ADS)

    Srinivasan, M. S.; McDowell, R. W.

    2009-12-01

    SummaryValidity of five empirical to process-based, hydrological models described by Srinivasan and McDowell (2007) in mapping transport areas was tested in the Invermay and Glenomaru headwater catchments in Otago, New Zealand. These transport areas together with contaminant source areas form critical source areas (CSAs), where the majority of contaminant loss occurs and therefore represent areas where mitigation potential would be most efficient. Rainfall and 15-min instantaneous surface flows at the catchment outlets and the shallow water table (<1 m from surface) dynamics within 5-40 m of perennial streams were recorded. In the Glenomaru deer sub-catchment, subsurface flow from a tile drain and surface flow in an ephemeral stream were also measured. In the Invermay catchment, surface soil moisture was recorded periodically during stormflow and baseflow periods to map the expansion and contraction of surface saturation areas. Analysis of spatial and time-series data from August 2006 to February 2008 indicated that during dry seasons (below-average rainfall periods), the majority of stormflow came from direct precipitation, wet areas (areas at or above saturation like deer wallows) adjacent to the stream and semi-pervious areas such as animal tracks. During wet periods (above-average rainfall), flow from these areas accounted for 10-70% of total stormflows. Water table data indicated that saturated areas with the water table at the surface rarely extended >10 m from the stream during storm events. There appeared to be an active subsurface (shallow) flow system transferring flows from land to streams. However, during many rainfall events, semi-pervious areas like fence lines, animal tracks and gateways were connected to the stream via infiltration-excess surface runoff, as measured by surface runoff samplers. This may be a significant for contaminant transfer given the amount of time spent by animals on these areas and deposition of contaminants (e.g., in dung) and

  5. Nitrate Removal Along a Colorado Montane Headwater Stream: the Role of Bidirectional Hydrologic Exchange at Reach to Catchment Scales

    NASA Astrophysics Data System (ADS)

    Smull, E. M.; Gooseff, M. N.

    2015-12-01

    Bidirectional hydrologic exchanges between streams and aquifers can influence nutrient concentrations (physical influx/efflux via gaining/losing water), and/or can facilitate biogeochemical cycling (physical and biological processes). Such exchanges therefore act to influence nutrient fate and transport, and have not yet been captured and incorporated into our understanding of stream nutrient retention and export. Along Colorado's Front Range, research in alpine and subalpine catchments has documented consistent increases in nitrate export, likely due to increased nitrogen deposition from industrialization and fertilization in eastern Colorado. The state of montane zone catchments with respect to their ability to cycle nitrate is not as well understood, however, and such ecosystems have complex hydrologic regimes relative to alpine areas. We applied a fully informed hydrologic mass balance model and nitrate mass balance model that include gross gains and gross losses (bidirectional exchanges) along a 1000 m study reach, to better understand physical and biological nitrate removal for a Colorado montane zone catchment, Lower Gordon Gulch. We collected data during five synoptic stream tracer and sampling campaigns along our study reach during the 2014-2015 water year, and installed wells along the north-facing and south-facing riparian corridor to capture changing water tables. Four distinct hydrologic regimes are captured in our results, including two experiments during baseflow, one experiment following snowmelt, one experiment following late-spring rainfall, and one experiment during the start of the seasonal hydrograph recession in mid-summer. Results show a transition from hydrologic sources of nitrate following snowmelt, to biological sources during rainfall, to biological removal during summer, and finally to hydrologic removal during baseflow. Our findings also corroborate earlier work in montane zone streams that shows preferential flow on south

  6. Hydrologic control of dissolved organic matter concentration and quality in a semiarid artificially drained agricultural catchment

    NASA Astrophysics Data System (ADS)

    Bellmore, Rebecca A.; Harrison, John A.; Needoba, Joseph A.; Brooks, Erin S.; Kent Keller, C.

    2015-10-01

    Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.

  7. Soft Water Level Sensors for Characterizing the Hydrological Behaviour of Agricultural Catchments

    PubMed Central

    Crabit, Armand; Colin, François; Bailly, Jean Stéphane; Ayroles, Hervé; Garnier, François

    2011-01-01

    An innovative soft water level sensor is proposed to characterize the hydrological behaviour of agricultural catchments by measuring rainfall and stream flows. This sensor works as a capacitor coupled with a capacitance to frequency converter and measures water level at an adjustable time step acquisition. It was designed to be handy, minimally invasive and optimized in terms of energy consumption and low-cost fabrication so as to multiply its use on several catchments under natural conditions. It was used as a stage recorder to measure water level dynamics in a channel during a runoff event and as a rain gauge to measure rainfall amount and intensity. Based on the Manning equation, a method allowed estimation of water discharge with a given uncertainty and hence runoff volume at an event or annual scale. The sensor was tested under controlled conditions in the laboratory and under real conditions in the field. Comparisons of the sensor to reference devices (tipping bucket rain gauge, hydrostatic pressure transmitter limnimeter, Venturi channels…) showed accurate results: rainfall intensities and dynamic responses were accurately reproduced and discharges were estimated with an uncertainty usually acceptable in hydrology. Hence, it was used to monitor eleven small agricultural catchments located in the Mediterranean region. Both catchment reactivity and water budget have been calculated. Dynamic response of the catchments has been studied at the event scale through the rising time determination and at the annual scale by calculating the frequency of occurrence of runoff events. It provided significant insight into catchment hydrological behaviour which could be useful for agricultural management perspectives involving pollutant transport, flooding event and global water balance. PMID:22163868

  8. Examining the linkages between forest water use, hydrology, and climate using dual-isotope approaches: insights and challenges in headwater catchments (Invited)

    NASA Astrophysics Data System (ADS)

    Barnard, H. R.; Brooks, J. R.; Pypker, T. G.; McDonnell, J. J.; Bond, B. J.; Williams, D. G.

    2010-12-01

    The amount of biologically available water is arguably the central driver in plant processes. While many studies have examined the hydrological components of biologically available water, the role that vegetation water use plays within the forested ecosystem water balance is poorly understood. Fundamental questions of forests' effect on the hydrologic cycle remain unanswered. Stable isotope observations play an important role in studies that explore the interface between plant physiological function and watershed flowpaths, flow sources, and residence times. We use multiple approaches, including stable isotopes to mechanistically assess the inter-relationships between vegetation water use, hydrology, and climate. We measured deuterium and 18O of xylem water and soil water to track changes in the depth of transpiration source water throughout the summers in a headwater catchment in western Oregon. Additionally, we measured transpiration, soil moisture, and foliar pre-dawn water potential. Forest transpiration and soil evaporation are often not separately measured, and yet respond to environmental drivers in fundamentally different ways. A promising approach for partitioning the evapotranspiration into its component fluxes involves measurement of the stable isotope composition (2H and 18O) of water vapor exchanged between vegetation and atmosphere. We present some preliminary data examining changes in ET partitioning in response to bark beetles outbreaks in the Rocky Mountains. Last, to examine the linkages between vegetation function and micro-climate, we applied a dual isotope (13C and 18O) approach to infer physiological response of trees to changing environmental conditions. We found that stable isotopes of oxygen were directly related to stomatal conductance and inversely related to relative humidity; however, the relationship with relative humidity was more apparent. The correlation of stable isotopes in tree rings with environmental variables can be

  9. Water Quality Response to Changes in Agricultural Land Use Practices at Headwater Streams in Georgia

    EPA Science Inventory

    Poorly managed agricultural watersheds may be one of the most important contributors to high levels of bacterial and sediment loadings in surface waters. We investigated two cattle farms with differing management schemes to compare how physicochemical and meteorological parameter...

  10. Comparison of hydrochemical tracers to estimate source contributions to peak flow in a small, forested, headwater catchment

    USGS Publications Warehouse

    Rice, Karen C.; Hornberger, George M.

    1998-01-01

    Three-component (throughfall, soil water, groundwater) hydrograph separations at peak flow were performed on 10 storms over a 2-year period in a small forested catchment in north-central Maryland using an iterative and an exact solution. Seven pairs of tracers (deuterium and oxygen 18, deuterium and chloride, deuterium and sodium, deuterium and silica, chloride and silica, chloride and sodium, and sodium and silica) were used for three-component hydrograph separation for each storm at peak flow to determine whether or not the assumptions of hydrograph separation routinely can be met, to assess the adequacy of some commonly used tracers, to identify patterns in hydrograph-separation results, and to develop conceptual models for the patterns observed. Results of the three-component separations were not always physically meaningful, suggesting that assumptions of hydrograph separation had been violated. Uncertainties in solutions to equations for hydrograph separations were large, partly as a result of violations of assumptions used in deriving the separation equations and partly as a result of improper identification of chemical compositions of end-members. Results of three-component separations using commonly used tracers were widely variable. Consistent patterns in the amount of subsurface water contributing to peak flow (45-100%) were observed, no matter which separation method or combination of tracers was used. A general conceptual model for the sequence of contributions from the three end-members could be developed for 9 of the 10 storms. Overall results indicated that hydrochemical and hydrometric measurements need to be coupled in order to perform meaningful hydrograph separations.

  11. Baseline Q-values for streams in intensive agricultural catchments in Ireland

    NASA Astrophysics Data System (ADS)

    Melland, Alice; Jordan, Phil; Wall, David; Mellander, Per-Erik; Mechan, Sarah; Shortle, Ger

    2010-05-01

    The effectiveness of regulations introduced in Ireland in 2006 in response to the European Union Nitrates Directives for minimising nutrient loss to waterways from farms is being studied by Teagasc, the Irish Agriculture and Food Development Authority as part of an Agricultural Catchments Programme from 2008 - 2011. The regulations in Ireland require that during winter, green cover is established and maintained on arable farms, manure is stored and not spread, ploughing is not conducted and that chemical fertiliser is not spread. The regulations also require buffer zones between fields and water courses when applying organic or chemical fertilisers and that nutrient application rates and timing match crop requirements. An upper limit for livestock manure loading of 170 kg ha-1 organic N each year is also set. The biophysical research component of the Agricultural Catchments Programme is focussed on quantifying nutrient source availability, surface and subsurface transport pathways and stream chemical water quality. A baseline description of stream ecological quality was also sought. Stream ecology was measured in autumn 2009 at 3-5 locations within four surface water catchments and at the spring emergence of a catchment underlain by karst limestone. Landuse in each catchment is dominated by medium to high intensity grassland or cereal farming and annual average rainfall ranges from 900 - 1200 mm. Surveys were conducted in 1st to 3rd order streams throughout each catchment at locations which had minimal observed point source inputs for 100m upstream, incomplete shade, a hard streambed substrate and riffle conditions suitable for the sampling methods. Benthic macroinvertebrates were identified and quantified and used to calculate the biological indices Small Stream Risk Score, Q-value, Biological Monitoring Working Party (BMWP), Average Score Per Taxa (ASPT) and EQR (Observed Q-value/Reference Q-value). Diatom community assemblages were identified from samples

  12. Plot and Catchment Scale Hydrological Impacts of Agricultural Field Boundary Features

    NASA Astrophysics Data System (ADS)

    Coates, Victoria; Pattison, Ian

    2015-04-01

    Natural flood management aims to reduce downstream flow levels by delaying the movement of water through a catchment and increasing the amount of soil infiltration. Field boundary features such as hedgerows and dry stone walls are common features in the rural landscape. It is hypothesised that there presence could reduce runoff connectivity and change the soil moisture levels by altering the soil structure and porosity. The use of larger agricultural machinery has resulted in the removal of field boundaries and the subsequent increase in field sizes over the 20th Century. This change in the rural landscape is likely to have changed the partitioning of rainfall into runoff and the hydrological pathways throughout the catchment. However, the link between field boundaries and catchment scale flood risk has not yet been proven. We aim to address this need for evidence to support natural flood management by focussing on these widespread features in the rural landscape. Firstly, we quantify the change in the density of field boundaries over the past 120 years for the Skell catchment, Northern England using historical OS maps. The analysis has shown that field size has approximately doubled in the Skell catchment since 1892, due to the removal of field boundaries. Secondly, we assess the effect of field boundaries on local soil characteristics and hydrological processes through plot scale continuous monitoring of the hydrological processes along a 20m transect through the linear boundary features. For the summer period results show that soil moisture levels are lower immediately next to the hedgerow compared to distances greater than 1m from the hedgerow. Finally, we use this data to parameterise and validate a catchment scale hydrological model. The model is then applied to test the impact of a network of field boundaries on river flow extremes at the catchment scale.

  13. Towards understanding the spatial and temporal characteristics of stream, hillslope, and groundwater runoff processes in a Rocky Mountain headwater catchment in Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Spencer, Sheena; Anderson, Axel; Silins, Uldis; Bladon, Kevin; Collins, Adrian

    2014-05-01

    The eastern slopes of the Rocky Mountains produce the majority of the surface water supplies for much of Alberta's population. Groundwater inputs to rivers constitutes a large component of flow in this headwater region, however limited knowledge of the interaction of groundwater-surface water sources limits the ability to predict impacts of climate and disturbance in this critical source water region. The objectives of this study are to explore the spatial and temporal dynamics of surface, hillslope, and deeper groundwater runoff processes using coupled tracer approaches to characterize their interaction in regulating streamflow dynamics at stream reach and catchment scales. The study was conducted in Star Creek (10.4 km2), which is representative of small-medium sized, front-range Rocky Mountain catchments. A network of climate stations and 6 nested hydrometric-water quality sampling stations were used to collect 5 years (2009 - 2013) of meteorological, discharge (Q), and stream water quality data. Nested stream gauging stations enabled characterization of the spatial and temporal pattern of Q and water geochemistry (cations: Na+, Mg2+, Ca2+, K+, and anions: Cl-, and SO42-) along a gradient of very steep, bedrock entrenched alpine stream reaches down through lower gradient mid-montane alluvial stream reaches. The initial phase of this work uses the stream gauging network to determine the difference in Q between stations, hydrograph baseflow separation, and mixing model analyses of geochemical parameters. These analyses suggest the runoff process is dominated by longer, deeper runoff flow pathways (groundwater). Geologic information and a conceptual model of topographic controls on hillslope-stream connectedness (after Jensco et al. 2009 and others) was used to identify sites where concentrated hillslope flow may be connected with the stream to aid in interpreting the spatial and temporal variation in Q and stream geochemistry. Strong longitudinal and seasonal

  14. Managing Artificially Drained Low-Gradient Agricultural Headwaters for Enhanced Ecosystem Functions

    PubMed Central

    Pierce, Samuel C.; Kröger, Robert; Pezeshki, Reza

    2012-01-01

    Large tracts of lowlands have been drained to expand extensive agriculture into areas that were historically categorized as wasteland. This expansion in agriculture necessarily coincided with changes in ecosystem structure, biodiversity, and nutrient cycling. These changes have impacted not only the landscapes in which they occurred, but also larger water bodies receiving runoff from drained land. New approaches must append current efforts toward land conservation and restoration, as the continuing impacts to receiving waters is an issue of major environmental concern. One of these approaches is agricultural drainage management. This article reviews how this approach differs from traditional conservation efforts, the specific practices of drainage management and the current state of knowledge on the ecology of drainage ditches. A bottom-up approach is utilized, examining the effects of stochastic hydrology and anthropogenic disturbance on primary production and diversity of primary producers, with special regard given to how management can affect establishment of macrophytes and how macrophytes in agricultural landscapes alter their environment in ways that can serve to mitigate non-point source pollution and promote biodiversity in receiving waters. PMID:24832519

  15. Occurrence of metolachlor and trifluralin losses in the Save river agricultural catchment during floods.

    PubMed

    Boithias, Laurie; Sauvage, Sabine; Taghavi, Lobat; Merlina, Georges; Probst, Jean-Luc; Pérez, José Miguel Sánchez

    2011-11-30

    Rising pesticide levels in streams draining intensively managed agricultural land have a detrimental effect on aquatic ecosystems and render water unfit for human consumption. The Soil and Water Assessment Tool (SWAT) was applied to simulate daily pesticide transfer at the outlet from an agriculturally intensive catchment of 1110 km(2) (Save river, south-western France). SWAT reliably simulated both dissolved and sorbed metolachlor and trifluralin loads and concentrations at the catchment outlet from 1998 to 2009. On average, 17 kg of metolachlor and 1 kg of trifluralin were exported at outlet each year, with annual rainfall variations considered. Surface runoff was identified as the preferred pathway for pesticide transfer, related to the good correlation between suspended sediment exportation and pesticide, in both soluble and sorbed phases. Pesticide exportation rates at catchment outlet were less than 0.1% of the applied amount. At outlet, SWAT hindcasted that (i) 61% of metolachlor and 52% of trifluralin were exported during high flows and (ii) metolachlor and trifluralin concentrations exceeded European drinking water standards of 0.1 μg L(-1) for individual pesticides during 149 (3.6%) and 17 (0.4%) days of the 1998-2009 period respectively. SWAT was shown to be a promising tool for assessing large catchment river network pesticide contamination in the event of floods but further useful developments of pesticide transfers and partition coefficient processes would need to be investigated.

  16. Pollution indicators in groundwater of two agricultural catchments in Lower Silesia (Poland)

    NASA Astrophysics Data System (ADS)

    Kasperczyk, Lidia; Modelska, Magdalena; Staśko, Stanisław

    2016-12-01

    The article discusses the content and source of mineral nitrogen compounds in groundwater, based on the data collected in two river catchments in two series (spring and autumn 2014). The study area comprises two catchments located in Lower Silesia, Poland - Cicha Woda and Sąsiecznica. Both catchments are characterised agricultural character of development. In the both researched areas, the points of State Environmental Monitoring (SEM) are located but only the Cicha Woda area is classified as nitrate vulnerable zone (NVZ). To analyse and compare the contamination of Quaternary and Neogene aquifers, the concentration of nitrates, nitrites, ammonium and potassium ions was measured primarily. Results showed the exceedance of nitrogen mineral forms of shallow groundwater Quaternary aquifer in both basins. The concentration of nitrates range from 0.08 to 142.12 mgNO3 -/dm3 (Cicha Woda) and from 2.6 to 137.65 mg NO3 -/dm3 (Sąsiecznica). The major source of pollution is probably the intensive agriculture activity. It causes a degradation of the shallow groundwater because of nitrate, nitrite, potassium, phosphates and ammonium contents. There was no observed contamination of anthropogenic origin in the deeper Neogene aquifer of Cicha Woda catchment.

  17. [Comparison of nitrogen loss via surface runoff from two agricultural catchments in semi-arid North China].

    PubMed

    Lu, Hai-Ming; Yin, Cheng-Qing; Wang, Xia-Hui; Zou, Ying

    2008-10-01

    Nitrogen loss characteristics via surface runoff from two typical agricultural catchments into Yuqiao Reservoir--the important drinking water source area for Tianjin city in semi-arid North China were investigated through two-year in-situ monitoring and indoor chemical analysis. The results showed that annual nitrogen export mainly concentrated in the rainy period between June to September. About 41% of the annual water output and 52% of the annual total nitrogen output took place in two rainfall events with rainfall> 60 mm in Taohuasi catchment (T catchment), while the distribution of water and nitrogen export among various rainfalls in Caogezhuang catchment (C catchment) was smooth. The rainfall thresholds for the appearance of water and nitrogen export from the outlet of T catchment and C catchment were 20 mm and 10 mm. The mean annual runoff coefficients of C and T catchments were 0.013 2 and 0.001 6, respectively. The mean annual total nitrogen exports from C catchment and T catchment were 1.048 kg x (hm2 x a)(-1) and 0.158 kg x (hm2 x a)(-1) respectively. The difference of micro-topography, landscape pattern and hydrological pathway between two catchments could explain the nitrogen export gap. Micro-topographical features created by long-term anthropological disturbance decrease the runoff generation ability. The distance between nitrogen source area and the outlet in T catchment was around 1 500 m, while such distance in C catchment was just around 200 m. The short distance added the nitrogen export risk via surface runoff. Road-type hydrological pathway in C catchment could transfer nitrogen into the receiving water via surface runoff directly, while nitrogen could be detained within the pathway by many sink structures such as small stones, vegetated buffer strip and dry ponds in T catchment.

  18. Agricultural management change effects on river nutrient yields in a catchment of Central Greece

    NASA Astrophysics Data System (ADS)

    Panagopoulos, Y.

    2009-04-01

    Modelling efforts are strongly recommended nowadays by European legislation for investigating non-structural mitigation measures against water pollution on catchment scale. Agricultural diffuse pollution is considered to be the main responsible human activity for the Eutrophication of inland waters with nitrogen (N) and phosphorus (P). The physically-based water quality model SWAT is implemented in an agricultural medium-size agricultural catchment of Central Greece with the purpose to simulate the baseline situation and subsequently to predict the effects that realistic non-structural interventions, applied on the agricultural land, have on water quality and crop yields. SWAT was successfully calibrated according to measured flows and water quality data and subsequently scenarios were developed by changing chemical fertilizer application rates and timing on corn, cotton and wheat cultivations. All scenarios resulted in a decrease of nutrient emissions to surface waters but with a simultaneous small decrease in crop yields. The model predicted explicitly the consequences of non-structural mitigation measures against water pollution sustaining that the understanding of land management changes in relation to its driving factors provides essential information for sustainable management of the agricultural sector in an agricultural country like Greece.

  19. Urbanization and agriculture increase exports and differentially alter elemental stoichiometry of dissolved organic matter (DOM) from tropical catchments.

    PubMed

    Gücker, Björn; Silva, Ricky C S; Graeber, Daniel; Monteiro, José A F; Boëchat, Iola G

    2016-04-15

    Many tropical biomes are threatened by rapid land-use change, but its catchment-wide biogeochemical effects are poorly understood. The few previous studies on DOM in tropical catchments suggest that deforestation and subsequent land use increase stream water dissolved organic carbon (DOC) concentrations, but consistent effects on DOM elemental stoichiometry have not yet been reported. Here, we studied stream water DOC concentrations, catchment DOC exports, and DOM elemental stoichiometry in 20 tropical catchments at the Cerrado-Atlantic rainforest transition, dominated by natural vegetation, pasture, intensive agriculture, and urban land cover. Streams draining pasture could be distinguished from those draining natural catchments by their lower DOC concentrations, with lower DOM C:N and C:P ratios. Catchments with intensive agriculture had higher DOC exports and lower DOM C:P ratios than natural catchments. Finally, with the highest DOC concentrations and exports, as well as the highest DOM C:P and N:P ratios, but the lowest C:N ratios among all land-use types, urbanized catchments had the strongest effects on catchment DOM. Thus, urbanization may have alleviated N limitation of heterotrophic DOM decomposition, but increased P limitation. Land use-especially urbanization-also affected the seasonality of catchment biogeochemistry. While natural catchments exhibited high DOC exports and concentrations, with high DOM C:P ratios in the rainy season only, urbanized catchments had high values in these variables throughout the year. Our results suggest that urbanization and pastoral land use exerted the strongest impacts on DOM biogeochemistry in the investigated tropical catchments and should thus be important targets for management and mitigation efforts.

  20. Use of isotopic and geochemical tracers to identify source waters, flow paths, and residence times of headwater catchments in Boulder Creek Watershed, Colorado

    NASA Astrophysics Data System (ADS)

    Cowie, R. M.; Williams, M. W.; Atkins, P. T.

    2009-12-01

    An outstanding question for snowmelt-dominated watersheds of the western US is the response of stream flow to changes in climate. We know little about mountain aquifers because they commonly involve structurally complicated rocks, extreme head gradients (ground slope angles 10-40°), and dramatically fluctuating recharge due to seasonal snow-melt. In general, the western United States is predicted to face warmer temperatures and more frequent and prolonged droughts, and we can expect to see a decrease in annual snowpack, earlier onset of snowmelt, and increased evaporation. Understanding streamflow generation under these climatic conditions will become increasingly important as hydrologic inputs change drastically and outputs are increasingly needed for human consumption. To improve our understanding of surface/groundwater interactions, we are simultaneously collecting surface water, subsurface, and precipitation samples at four gauged headwater catchments along a 1,500-m elevational gradient in the Boulder Creek Critical Zone Observatory: (1) Green Lakes Valley (3,500 m); (2) Como Creek (2,900 m); (3) Gordon Gulch (2,400 m); and Betasso (1,830 m). All water samples are analyzed for geochemical and isotopic (δ18O, δD) composition. The average residence time for subsurface flow is calculated by comparing the smoothing of the δ18O input (precipitation) and output (streamflow) using a convolution algorithm. The calculation of residence times is also constrained by measuring concentrations of tritium (3H), a naturally occurring radioisotope, to better understand sub-surface transit times. A two-component mixing model will be used to determine source waters from old (reacted) waters and new (unreacted) waters. End member mixing analysis (EMMA) is a statistically unbiased technique that will also be used to identify the most important end members contributing to stream flow. The application of Principle Component Analysis (PCA) using all of the isotopic and

  1. Evaluation of High-Temporal-Resolution Bedload Sensors for Tracking Channel Bed Movement and Transport Thresholds in Forested Mountain Headwater Catchments.

    NASA Astrophysics Data System (ADS)

    Martin, S.; Conklin, M. H.; Bales, R. C.

    2014-12-01

    High temporal resolution data is required to take channel bed movement data beyond time integrated changes between measurements where many of the subtleties of bedload movement patterns are often missed. This study used continuous bedload scour sensors (flexible, fluid-filled pans connected to a pressure transducer) to collect high temporal resolution, long term bedload movement data for 4 high elevation (1500-1800 m) Sierra Nevada headwater streams draining 1 km2 catchments and to investigate the physical channel characteristics under which they perform best. Data collected by the scour sensors were used to investigate the disturbance and recovery patterns of these streams, to relate the observed patterns to channel bed stability, and to evaluate whether the channel bed is acting as a sediment source, sink, or storage across various temporal scales. Finally, attempts are made to identify discharge thresholds for bed movement from scour sensor and discharge data and to compare these threshold values to observed changes in the channel bed. Bedload scour data, turbidity data, and stream discharge data were collected at 15 minute intervals for (WY 2011 to WY 2014), including both above average (2011) and below average (2012, 2013, 2014) water years. Bedload scour sensors were found to have a relatively high (60%) failure rate in these systems. In addition, they required in situ calibrations as the factory and laboratory calibrations did not translate well to the field deployments. Data from the working sensors, showed patterns of abrupt channel bed disturbance (scour and/or fill) on an hour to day temporal scale followed by gradual recovery on a day to month scale back to a stable equilibrium bed surface elevation. These observed patterns suggest the bed acts as a short term source or sink for sediment, but is roughly sediment neutral over longer time periods implying the changes in bed elevation are reflective of fluctuations in storage rather than a true source or

  2. Assessing the sustainability of agriculture: a case of Mae Chaem Catchment, northern Thailand.

    PubMed

    Praneetvatakul, S; Janekarnkij, P; Potchanasin, C; Prayoonwong, K

    2001-09-01

    Sustainability is not a new concept but rather a prominent concept at the present time. Researchers have categorized sustainability indicators into economic, social, and ecological aspects. Sustainability of agriculture in the context of development efforts has to meet production efficiency, resilience of ecosystems, appropriate technology, maintenance of the environment, cultural diversity, and satisfaction of the basic needs. The research objective of this study is to determine the critical indicators of agricultural sustainability in the Mae Chaem Catchment, northern Thailand. In assessing sustainability, the authors applied the sustainability indicator analysis developed by FAO. The results of the study show that food sufficiency in the Wat Chan subcatchment is the most sustainable aspect of agriculture. The least sustainable facets of agriculture in the Wat Chan subcatchment are land holding size, land tenure, and water shortage. While expansion of agricultural land in the watershed area is not legally permitted, a practice of agroforestry is recommended. Insecure land tenure may result in reduced incentives to improve land productivity. Thus, official recognition of land ownership is required. As the problem of water shortage is most critical in the lower reaches, increased participation in the allocation scheme by downstream villagers should be encouraged. Finally, the construction of a small-scale water storage in the lower part of the catchment to increase water supply should be considered.

  3. Modelling the effects of recent agricultural land use change on catchment flow and sediment generation

    NASA Astrophysics Data System (ADS)

    Escobar Ruiz, Veronica; Smith, Hugh; Blake, William

    2016-04-01

    Intensive agricultural practices can exacerbate runoff and soil erosion leading to detrimental impacts downstream. Physically-based models have previously been used to assess the impacts on flow and sediment transport in response to land use change, but there has been little investigation of the effect shorter-term changes linked to variations in the extent of cultivated land. The aim of this project is to quantify the impacts on flow generation and sediment transport of different catchment conditions related to both actual recent changes in agricultural land use as well as future change scenarios. To this end, a physically-based distributed hydrological model, SHETRAN was applied in the Blackwater catchment (12 km2) located in south-west England. Land cover was simulated on the basis of satellite-derived land cover maps (1990, 2000 and 2007) as well as a catchment-scale field survey (2011). Soils were represented in the model using five layers for five different soil types in which parameter values were varied in accordance with land use and literature values. Rainfall data (15 min) combined with monthly calculations of evapotranspiration using a simple temperature-based PE model were used to represent contemporary climatic conditions spanning 2010-2014. Calibration was undertaken for selected events during 2011 when land use information was concurrent with available flow and suspended sediment yield data. All land use simulations were then completed for the period 2010-2014 to enable the comparison of model outputs. This contribution will present preliminary results from these land use simulations alongside the effect of several future changes scenarios on catchment flow and sediment generation.

  4. Evaluation of nitrate removal in buffer zone supply by water from agricultural drained catchment

    NASA Astrophysics Data System (ADS)

    Fesneau, Corinne; Tournebize, Julien; Chaumont, Cedric; Guenne, Angeline

    2010-05-01

    The European Directive 2000/60/CE states objectives of a good ecological and chemical status from water body until 2015. The Cemagref project focuses on the constructed wetlands (CW) which can be used as buffer zones to lower the impact of agricultural practices on hydrosystems and decrease or even stop the transfer of contaminants via the surface waters. The experiments are carried out on a drained area where the runoff is limited and waters from the soil profile are concentrated at the drain pipes outlet. The constructed wetland studied is located at Aulnoy (77) at 70 km north-east of Paris, within the Orgeval catchment (France). Our aim is to assess the efficiency of constructed wetlands on the removal of agricultural nitrates. We are also interested in the hydrological balance of CW and agricultural catchment. The buffer zone is connected to a drained agricultural catchment of 35 hectares. The crops in the agricultural plots mainly consist in cereals (corn, maize), vegetables (horse bean, pea), sugar beet and rape. Nitrogen fertilizers are applied following normal agricultural practices. The site is monitored since 2005 for discharge and nitrate concentration in order to infer water and nitrate budgets. The buffer zone includes a pond (860m2) and a reservoir (3305 m2). The storage volume is estimated to 8000m3 which corresponds to about 10% of drainage runoff. Our study reveals potential nitrate removal because a decrease of nitrate average contents has been documented between inlet and outlet CW over a measurement period of 4 years. Average values of 57 mg/l, 40 mg/l and 27 mg/l are respectively measured at the main drain, in the pond mean and in the reservoir; that is a reduction close to 50% of nitrate fluxes. The semi-potential denitrification experiments confirm the denitrification capacity of buffer zone sediments. This constructed wetland allows the treatment of waters from agricultural drainage and provides results in line with the expectations of "good

  5. Source and transport factors influencing storm phosphorus losses in agricultural catchments

    NASA Astrophysics Data System (ADS)

    Shore, Mairead; Jordan, Phil; Mellander, Per-Erik; kelly-quinn, Mary; Wall, David; Murphy, Paul; Melland, Alice

    2014-05-01

    The relative risk of diffuse phosphorus (P) loss from agricultural land was assessed in a well-drained arable catchment and a poorly-drained grassland catchment and in two nested basins within each catchment. This research investigated the relative control of hydrology and soil P on P losses between basins. Quick flow (QF) P losses (defined here as both concentrations and loads), monitored in stream flow during four storm events, were compared with a dynamic metric of transport risk (QF magnitude) and a static metric of critical source area (CSA) risk (extent of highly-connected poorly-drained soils with excess plant-available soil P). The potential for static transport metrics of soil connectivity and soil drainage class, to predict relative QF magnitudes and P losses between basins was also investigated. In basins with similar CSA risk but with contrasting QF magnitudes, mean TRP (total molybdate-reactive P) losses were consistently higher in the basins which had the highest QF magnitudes. This suggests that basin hydrology, rather than hydrology of high-P soils only, determined relative TRP losses between hydrologically contrasting basins. Furthermore, static transport metrics of soil connectivity and soil drainage class reliably discerned relative QF magnitudes and TRP losses between these basins. However, for two of the storm events (both occurring during the hydrologically active season), PP (particulate P) concentrations were frequently higher in basins which had the lowest QF magnitudes and may be attributed to a higher proportion of bare soil in these basins at these times as a result of their predominantly arable nature. In basins with similar hydrology, relative TRP and PP losses did not reflect trends in CSA risk or QF magnitude. The dynamics of TRP and PP losses and QF magnitude between these basins varied across storms, thus could not be predicted using static metrics. Where differences in hydrological dynamics were large, storm TRP losses were well

  6. Identifying priority zones in an agricultural catchment to mitigate glyphosate runoff

    NASA Astrophysics Data System (ADS)

    Joris, Ingeborg; Desmet, Nele; Wilczek, Daniel; Boënne, Wesley; Seuntjens, Piet; Koopmans, Kim; Bylemans, Dany; Wouters, Katrien; Vandaele, Karel

    2015-04-01

    Pesticide concentrations in rivers generally have a very dynamic signature and are strongly dependent on time and space. The dynamic time course is due to the time- and space-variant input conditions resulting from fast overland (runoff and erosion, direct losses) and subsurface flow (artificial drainage), directly connecting surfaces and/or agricultural fields where pesticides are applied, to receiving rivers. A thorough understanding of pesticide behavior at the watershed scale is needed to increase the effectiveness of mitigation measures. We developed a method to derive priority zones for applying mitigation measures for erosion control and mitigation of glyphosate runoff in an agricultural catchment. The study catchment was selected based on results from geospatial pesticide emission modeling, historical glyphosate concentrations, and crop cover. Priority zones were derived based on a risk map which includes information about the topography, crop cover, the estimated glyphosate use, the potential erosion risk, and the connectivity of the agricultural parcels to the river. The theoretical risk map was then validated in the field using field observations of runoff during stormflow events, and observations of roads short-circuiting the runoff to the river. The validated risk map was used to define priority zones for measures related to erosion control. Suggestions for specific measures such as grass buffer strips and small dams at the field scale were made. The information will be used to target farmers that may have a significant impact on the glyphosate load to surface water. Those farmers will be encouraged to participate in a voluntary erosion control program supported by the local government. The effect of mitigation measures on the glyphosate concentrations in the river will be assessed by monitoring two years before and three years after implementation of the measures. We will present the general setup of the study and the selection methodology of the

  7. Public Health Perspectives of Channelized and Unchannelized Headwater Streams in Central Ohio: A Case Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Headwater streams constitute the majority of watersheds in the United States and many headwater streams in the midwest have been channelized for agricultural drainage. Public health implications of water chemistry and aquatic macroinvertebrates within channelized and unchannelized headwater streams ...

  8. [Phosphorus Fractions and Release Risk in Surface Sediments of an Agricultural Headwater Stream System in Hefei Suburban, China].

    PubMed

    Pei, Ting-ting; Li, Ru-zhong; Gao, Su-di; Luo, Yue-ying

    2016-02-15

    A typical water system of agricultural headwater stream in Chaohu Lake basin was selected as the study area, and 17, 16, 14 and 13 surface sediments were collected from the four styles of stream, respectively, including ponds, branches, main channel and mainstream deep pools, in October 2014 (in autumn) and April 2015 (in spring). The forms and space-time variations of phosphorus in the sediments were analyzed. Clustering and variance analysis were conducted on the phosphorus forms data from the four styles of stream by means of multivariate statistical analyses. We quantified the phosphorus release risk (PSI) and identified the main impact factors of PSI via calculating the phosphorus sorption index (PSI) and the correlation analysis. The results showed that: (1) The contents of TP in the surface sediments ranged from 137.517 to 1709.229 mg x kg(-1) with an average value of 532. 245 mg x kg(-1), and the order of the average contents of phosphorus forms was IP (350.347 mg x kg(-1)) > OP (167.333 mg x kg(-1)) > Fe/Al-P ( 78. 869 mg x kg(-1)) > Ca-P (56.343 mg x kg(-1)) > Ex-P (6.609 mg x kg(-1)); (2) The contents of phosphorus forms had the same trend in all the four stream styles, which was deep pool > main channel > branch > pond; (3) In autumn, the deep pool and main channel were clustered into one class, while the pond and branch were clustered into the other class. In spring, branch, main channel and deep pool were clustered into the same class; (4) Variance analysis showed that the differences among the four stream styles were larger in autumn than in spring; (5) The PSI of the surface sediments ranged between 24.49 and 69.94 (mg x L(-1) x (100 g x micromol)(-1). The PSI in spring was lower than that in spring, indicating that phosphorus release risk of surface sediment was higher in spring than in autumn. (6) PSI had a significant negative correlation with Ex-P, IP and pH.

  9. Influence of adding small instream wood on fishes and hydrology within channelized agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large instream wood is well known for its importance in headwater streams because it promotes the development of pool habitat for fishes and provides them with cover from predators during the summer. However, little is known about the influence of small instream wood (diameter < 10 cm, length < 1 m...

  10. Intensive rice agriculture deteriorates the quality of shallow groundwater in a typical agricultural catchment in subtropical central China.

    PubMed

    Wang, Yi; Li, Yuyuan; Li, Yong; Liu, Feng; Liu, Xinliang; Gong, Dianlin; Ma, Qiumei; Li, Wei; Wu, Jinshui

    2015-09-01

    High nitrogen (N) concentrations in rural domestic water supplies have been attributed to excessive agricultural N leaching into shallow groundwater systems; therefore, it is important to determine the impact of agriculture (e.g., rice production) on groundwater quality. To understand the impact of agricultural land use on the N concentrations in the shallow groundwater in subtropical central China, a large observation program was established to observe ammonium-N (NH4-N), nitrate-N (NO3-N), and total N (TN) concentrations in 161 groundwater observation wells from April 2010 to November 2012. The results indicated that the median values of NH4-N, NO3-N, and TN concentrations in the groundwater were 0.15, 0.39, and 1.38 mg N L(-1), respectively. A total of 36.3 % of the water samples were categorized as NH4-N pollution, and only a small portion of the samples were categorized as NO3-N pollution, based on the Chinese Environmental Quality Standards for Groundwater of GB/T 14848-93 (General Administration of Quality Supervision of China, 1993). These results indicated of moderate groundwater NH4-N pollution, which was mainly attributed to intensive rice agriculture with great N fertilizer application rates in the catchment. In addition, tea and vegetable fields showed higher groundwater NO3-N and TN concentrations than other agricultural land use types. The factorial correspondence analysis (FCA) suggested that the flooded agricultural land use types (e.g., single-rice and double-rice) had potential to impose NH4-N pollution, particularly in the soil exhausting season during from July to October. And, the great N fertilizer application rates could lead to a worse NO3-N and TN pollution in shallow groundwater. Hence, to protect groundwater quality and minimize NH4-N pollution, managing optimal fertilizer application and applying appropriate agricultural land use types should be implemented in the region.

  11. Modeling water flow in a tile drainage network in glacial clayey tills in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    De Schepper, G.; Therrien, R.; Refsgaard, J.

    2013-12-01

    Tile drainage is a widespread water management practice applied to poorly drained production fields to increase crop productivity and reduce flooding risks. A challenge associated with water resources management in agricultural catchments is to properly understand and quantify the role of tile drainage for the catchment water balance. Only a few studies have been presented where different numerical modeling approaches were tested to simulate tile drainage at the field or catchment scale. These studies suggest that challenges still remainto represent correctly subsurface drainage networks in numerical models while accounting for their influence on water flow and transport. To investigate the impact of tile drains, a variably-saturated flow model has been applied to the Lillebaek agricultural catchment, Denmark. The Lillebaek catchment covers 5 ha and is underlain by about 30 m of Quaternary deposits that consist of a local sandy aquifer with upper and lower clayey till units. A tile drainage network is located in the upper clay till. Water table elevations are recorded daily in a network of piezometers within the catchment, as well as drainage and stream discharge. The control volume finite element HydroGeoSphere model is used to simulate 3D variably-saturated flow in the catchment, coupled with 1D open-channel flow in tile drains and 2D overland flow. That approach requires that the tile drainage network be represented explicitly in the model with 1D elements. The 3D field-scale hydrogeological model was first generated from a national-scale geological model for Denmark combined with available local borehole data. A reference model was then generated for 3D variably-saturated subsurface flow coupled with 2D overland flow. That reference model also incorporates discrete 1D elements to represent the entire drainage network, with a critical depth boundary condition applied to the outlet of the drainage networks. A series of simulation were performed to test the

  12. Effect of Agricultural Practices on Hydrology and Water Chemistry in a Small Irrigated Catchment, Yakima River Basin, Washington

    USGS Publications Warehouse

    McCarthy, Kathleen A.; Johnson, Henry M.

    2009-01-01

    The role of irrigation and artificial drainage in the hydrologic cycle and the transport of solutes in a small agricultural catchment in central Washington's Yakima Valley were explored using hydrologic, chemical, isotopic, age-dating, and mineralogical data from several environmental compartments, including stream water, ground water, overland flow, and streambed pore water. A conceptual understanding of catchment hydrology and solute transport was developed and an inverse end-member mixing analysis was used to further explore the effects of agriculture in this small catchment. The median concentrations of major solutes and nitrates were similar for the single field site and for the catchment outflow site, indicating that the net effects of transport processes for these constituents were similar at both scales. However, concentrations of nutrients were different at the two sites, suggesting that field-scale variations in agricultural practices as well as nearstream and instream biochemical processes are important components of agricultural chemical transformation and transport in this catchment. This work indicates that irrigation coupled with artificial drainage networks may exacerbate the ecological effects of agricultural runoff by increasing direct connectivity between fields and streams and minimizing potentially mitigating effects (denitrification and dilution, for example) of longer subsurface pathways.

  13. Hydrogeologic controls on nitrate transport in a small agricultural catchment, Iowa

    USGS Publications Warehouse

    Schilling, K.E.; Tomer, M.D.; Zhang, Y.-K.; Weisbrod, T.; Jacobson, P.; Cambardella, C.A.

    2007-01-01

    Effects of subsurface deposits on nitrate loss in stream riparian zones are recognized, but little attention has been focused on similar processes occurring in upland agricultural settings. In this paper, we evaluated hydrogeologic controls on nitrate transport processes occurring in a small 7.6 ha Iowa catchment. Subsurface deposits in the catchment consisted of upland areas of loess overlying weathered pre-Illinoian till, drained by two ephemeral drainageways that consisted of Holocene-age silty and organic rich alluvium. Water tables in upland areas fluctuated more than 4 m per year compared to less than 0.3 m in the drainageway. Water quality patterns showed a distinct spatial pattern, with groundwater in the drainageways having lower nitrate concentrations (10 mg L-1) as wells as lower pH, dissolved oxygen and redox, and higher ammonium and dissolved organic carbon levels. Several lines of evidence suggested that conditions are conducive for denitrification of groundwater flowing from uplands through the drainageways. Field-measured nitrate decay rates in the drainageways (???0.02 day-1) were consistent with other laboratory studies and regional patterns. Results from MODFLOW and MT3DMS simulations indicated that soils in the ephemeral drainageways could process all upland groundwater nitrate flowing through them. However, model-simulated tile drainage increased both water flux and nitrate loss from the upland catchment. Study results suggest that ephemeral drainageways can provide a natural nitrate treatment system in our upland glaciated catchments, offering management opportunities to reduce nitrate delivery to streams. Copyright 2007 by the American Geophysical Union.

  14. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; description and water quality of the Little Conestoga Creek headwaters prior to the implementation of nutrient management

    USGS Publications Warehouse

    Fishel, D.K.; Brown, M.J.; Kostelnik, K.M.; Howse, M.A.

    1992-01-01

    The headwaters of the Conestoga River are being studied to determine the effects of agricultural Best-Management Practices on surface-water and ground-water quality. As part of this study, a 5.82-square-mile area of the Little Conestoga Creek headwaters (Small Watershed) was monitored during 1984-86, prior to implementation of Best-Management Practices. This report describes the land use and hydrology of this study area and characterizes its surface-water and ground-water quality during the pre-Best-Management Practice phase. During base-flow conditions, median concentrations of dissolved nitrite plus nitrate nitrogen as nitrogen increased from 2.7 to 8.1 milligrams per liter as the stream flowed through the intensively-farmed carbonate valley. Median total phosphorus increased from 0.05 to 0.20 milligram per liter. Concentrations of dissolved nitrate nitrogen as nitrogen measured in ground water in carbonate rocks in the valley were as great as 25 milligrams per liter and consistently exceeded 10 milligrams per liter. Statistical analysis showed that it will require substantial reductions in concentrations and discharges of nitrogen and phosphorus in base flow to obtain statistically measurable improvements in water quality. If concentrations and discharges of total nitrogen in base flow at the five sites are reduced by 15 to 33 percent, and by 63 to 70 percent, respectively, then the Wilcoxon Mann-Whitney rank-sum test will be able to detect an improvement in water quality 95 percent of the time. Likewise, if concentrations of total phosphorus are reduced by 36 to 54 percent, or discharges of total phosphorus are reduced by 52 to 69 percent at the five sites, then an improvement in water quality will be able to be detected 95 percent of the time.

  15. Nutrient cycles in agricultural systems at sub-catchment scale within the UK and China

    NASA Astrophysics Data System (ADS)

    Bellarby, Jessica; Surridge, Ben; Haygarth, Philip M.; Lai, Xin; Zhang, Guilong; Song, Xiaolong; Zhou, Jianbin; Meng, Fanqiao; Shen, Jianbo; Rahn, Clive; Smith, Laurence; Burke, Sean

    2015-04-01

    Diffuse water pollution from agriculture (DWPA) represents a significant challenge in both the UK and China. The UK has developed policies and practices which seek to mitigate DWPA, yet the risks and adverse impacts of DWPA remain widespread. In contrast, China's past priorities have largely focussed on food security, with an emphasis on increasing food production through high fertiliser application rates with little attention being paid to enhanced nutrient export from land to water and to air. This has contributed to severe environmental problems which are only now beginning to be recognised and addressed. We have prepared nutrient balances (phosphorus and nitrogen) in contrasting agricultural production systems at sub-catchment scale within China and the UK. These draw from a variety of sources ranging from general yearly statistics collected by the respective government to farm surveys. Our aim is to use the resulting nutrient balances to underpin the sharing of knowledge and innovation to mitigate DWPA in both nations. In the UK, the case studies focus on the three Demonstration Test Catchment locations, covering a range of livestock and arable production systems across England. Here, the high frequency monitoring of phosphorus river loads enables the cross-validation of the simple nutrient budget approaches applied in this study. In China, our case studies span kiwi orchard, fruit and vegetable solar greenhouse systems, double cropped rice-wheat and wheat-maize production systems. Substantial differences in nutrient stocks and flows exist between individual production systems both across and within the two countries. These differences will be expressed along the source-mobilisation-delivery-impact continuum that underpins our budgets for both phosphorus and nitrogen. We will present the phosphorus cycles of some case studies and highlight their challenges and relevance at sub-catchment scale. Based on our nutrient budgets, general recommendations can be

  16. Managing the drinking water catchment areas: the French agricultural cooperatives feed back.

    PubMed

    Charrière, Séverine; Aumond, Claire

    2016-06-01

    The quality of raw water is problematic in France, largely polluted by nitrates and pesticides (Mueller and Helsel, Nutrients in the nation's waters-too much of a good thing? Geological Survey (U.S.), 1996; European Environment Agency, European waters-assessment of status and pressures, 2012).This type of pollution, even though not always due to agriculture (example of the catchment of Ambleville, county 95, France where the nitrate pollution is mainly due to sewers (2012)), has been largely related to the agricultural practices (Sci Total Environ 407:6034-6043, 2009).Taking note of this observation, and instead of letting it paralyze their actions, the agricultural cooperatives decided with Agrosolutions to act directly on the field with their subscribers to change the agricultural practices impacting the water and the environment.This article shows how the French agricultural cooperatives transformed the awareness of the raw water quality problem into an opportunity for the development and implementation of more precise and responsible practices, to protect their environment. They measure in order to pilot, co-construct and build the best action plans possible according to the three pillars of environment, economy and agronomy.

  17. Water ponding and catchment runoff as influenced by conservation agriculture in May Zeg-zeg (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Lanckriet, Sil; Nyssen, Jan; Araya, Tesfay; Poesen, Jean; Govaerts, Bram; Bauer, Hans; Deckers, Jozef; Haile, Mitiku; Verfaillie, Els; Cornelis, Wim M.

    2013-04-01

    This study evaluates the practice of conservation agriculture (CA) in the May Zeg-zeg catchment (MZZ; 187 ha) in the North Ethiopian Highlands as a soil management technique for reducing soil loss and runoff, and assesses the consequences of future large-scale implementation on soil and hydrology at catchment-level. The study of such practice is important especially under conditions of climate change, since EdGCM (Educational Global Climate Model) simulation predicts by 2040 an increase in precipitation by more than 100 mm yr-1 in the study area. Firstly, field-saturated infiltration rates, together with soil texture and soil organic carbon contents, were measured. Relation with local topography allows to generate a pedotransfer function for field-saturated infiltration rate, and spatial interpolation with Linear Regression Mapping was used to map field-saturated infiltration rates optimally within the catchment. Secondly, on several farmlands, CA was checked against Plain Tillage (PT) for values of field-saturated infiltration rates, soil organic carbon, runoff and soil loss. Results show no significant differences for infiltration rates but significant differences for runoff and soil loss (as measured in the period 2005-2011). Runoff coefficients were 30.4% for PT and 18.8% for CA; soil losses were 35.4 t ha-1 yr-1 for PT and 14.4 t ha-1 yr-1 for CA. Thirdly, all collected information was used to predict future catchment hydrological response for full-implementation of CA under the predicted wetter climate (simulation with EdGCM). Curve Numbers for farmlands with CA were calculated. An area-weighted Curve Number allows the simulation of the 2011 rainy season runoff, predicting a total runoff depth of 23.5 mm under CA and 27.9 mm under PT. Furthermore, the Revised Universal Soil Loss Equation management factor P was calibrated for CA. Results also show the important influence of increased surface roughness on water ponding, modeled with a hydrologic conservation

  18. Catchment-scale evaluation of environmental regulations in the agricultural sector in Ireland (Invited)

    NASA Astrophysics Data System (ADS)

    Melland, A. R.; Jordan, P.; Mellander, P.; Wall, D. J.; Buckley, C.; Mechan, S.; Shortle, G.

    2010-12-01

    The European Union (EU) Nitrates Directive regulations in Ireland limits the use of agricultural fertilisers to agronomic optima and aims to minimise surplus phosphorus (P) and nitrogen (N) losses to the aquatic environment. The legislated measures include limits on nutrient application according to soil P status, crop type and livestock intensity and restricts chemical and organic fertiliser spreading and ploughing to periods of the year with typically lower exposure of nutrients to runoff and leaching. These agricultural policies are being evaluated in an Agricultural Catchments Programme in six representative catchments dominated by moderate to high intensity grassland and arable enterprises across Ireland (Fealy et al., 2010). An experimental programme has been established to provide a baseline of farm nutrient management and water body quality during the early years of the measures and to provide estimates of trajectories towards (or otherwise) water quality targets. A ‘nutrient transfer continuum’ from source, through pathways, to delivery and impact in a water body receptor describes the different phases of diffuse pollution and is being used as a framework for evaluation. Compliance with Irish standards at different levels of the continuum is being evaluated and demonstrative studies are being conducted to provide evidence of linkages between source and delivery to validate conceptual models of P and N transfers in time and space in each catchment. Source compliance is being evaluated through census soil testing and a survey of nutrient management practice and farmyard infrastructure. Mobilisation and pathways of nutrient transfers do not have chemical standards except where a groundwater body acts as both a receptor and a pathway. To demonstrate these linkages, however, representative groundwater pathways are being monitored through piezometer, chemical end-member and tracer studies, and surface water pathways are being evaluated through subcatchment

  19. Response of current phosphorus mitigation measures across the nutrient transfer continuum in two hydrological contrasting agricultural catchments

    NASA Astrophysics Data System (ADS)

    McDonald, Noeleen; Shore, Mairead; Mellander, Per-Erik; Shortle, Ger; Jordan, Phil

    2015-04-01

    Effective assessment of National Action Programme (NAP) measures introduced under the EU Nitrates Directive (ND), to manage nutrient use and risk of loss to waters from agriculture, is best achieved when examined across the nutrient transfer continuum at catchment scale. The Irish NAP measures are implemented on a whole-territory basis for both nitrogen (N) and phosphorus (P), with P being the key trophic pressure. The aim of this research was to observe the efficacy of P regulation measures and P source management across the transfer continuum and resultant water quality status (i.e. source to impact), in two contrasting agricultural catchments over a four year period. The catchments are ca. 11 km2 and are located in the south-east of Ireland. One is well-drained and arable dominated, while the other is mostly poorly-drained and grassland dominated. In 2009 and 2013 soil surveys for plant-available P were carried out (<2 ha sample areas) in both catchments. Concurrently, high temporal resolution monitoring of water discharge and P concentration was conducted at each catchment outlet across four hydrological years (April to March). Ecological impact surveys were carried out at four sites within each catchment in May and September across the observed four year period (2009-2013). Importantly, the proportion of farmland with excessive soil P concentrations decreased in both the arable (20% to 11.8%) and grassland catchments (5.9 to 3.6%). However, soil P concentrations also declined critically in both catchments, as proportional areas below the national crop agronomic optimum thresholds (grassland; <5 mg P l-1, arable; <6 mg P l-1) increased from 57% to 68% in the arable catchment and 75% to 87% in the grassland catchment. This decline in plant available P strongly indicates a reduced or sustained level of P inputs in both catchments. Indications of responses to soil P change in the surface waters of these catchments appeared to be highly influenced by their

  20. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; effects of nutrient management on water quality in the Little Conestoga Creek headwaters, 1983-89

    USGS Publications Warehouse

    Koerkle, E.H.; Fishel, D.K.; Brown, M.J.; Kostelnik, K.M.

    1996-01-01

    Water quality in the headwaters of the Little Conestoga Creek, Lancaster County, Pa., was investigated from April 1986 through September 1989 to determine possible effects of agricultural nutrient management on water quality. Nutrient management, an agricultural Best-Management Practice, was promoted in the 5.8-square-mile watershed by the U.S. Department of Agriculture Rural Clean Water Program. Nonpoint-source- agricultural contamination was evident in surface water and ground water in the watershed; the greatest contamination was in areas underlain by carbonate rock and with intensive row-crop and animal production. Initial implementation of nutrient management covered about 30 percent of applicable land and was concentrated in the Nutrient-Management Subbasin. By 1989, nutrient management covered about 45 percent of the entire Small Watershed, about 85 percent of the Nutrient- Management Subbasin, and less than 10 percent of the Nonnutrient-Management Subbasin. The number of farms implementing nutrient management increased from 14 in 1986 to 25 by 1989. Nutrient applications to cropland in the Nutrient- Management Subbasin decreased by an average of 35 percent after implementation. Comparison of base- flow surface-water quality from before and after implementation suggests that nutrient management was effective in slowing or reversing increases in concentrations of dissolved nitrate plus nitrite in the Nutrient-Management Subbasin. Although not statistically significant, the Mann-Whitney step-trend coefficient for the Nutrient-Management Subbasin was 0.8 milligram per liter, whereas trend coefficients for the Nonnutrient-Management Subbasin and the Small Watershed were 0.4 and 1.4 milligrams per liter, respectively, for the period of study. Analysis of covariance comparison of concurrent concentrations from the two sub- basins showed a significant decrease in concen- trations from the Nutrient-Management Subbasin compared to the Nonnutrient-Management Subbasin

  1. Estimating the Regional Flux of Nitrate and Agricultural Herbicide Compounds from Groundwater to Headwater Streams of the Northern Atlantic Coastal Plain, USA

    NASA Astrophysics Data System (ADS)

    Ator, S.; Denver, J. M.

    2011-12-01

    Agriculture is common in the Northern Atlantic Coastal Plain (NACP, including New Jersey through North Carolina), and groundwater discharge provides nitrogen (primarily in the form of nitrate) and herbicide compounds from agricultural sources along with the majority of flow to NACP streams. Poor water quality has contributed to ecological degradation of tidal streams and estuaries along much of the adjacent mid-Atlantic coast. Although statistical models have provided estimates of total instream nutrient flux in the Coastal Plain, the regional flux of nitrogen and herbicides during base flow is less well understood. We estimated the regional flux of nitrate and selected commonly used herbicide compounds from groundwater to non-tidal headwater streams of the NACP on the basis of late-winter or spring base-flow samples from 174 such streams. Sampled streams were selected using an unequal-probability random approach, and flux estimates are based on resulting population estimates rather than empirical models, which are commonly used for such estimates. Base-flow flux in the estimated 8,834 NACP non-tidal headwater streams are an estimated 21,200 kilograms per day of nitrate (as N) and 5.83, 0.565, and 20.7 kilograms per day of alachlor, atrazine, and metolachlor (including selected degradates), respectively. Base-flow flux of alachlor and metolachlor is dominated by degradates; flux of parent compounds is less than 3 percent of the total flux of parent plus degradates. Base-flow flux of nitrate and herbicides as a percentage of applications generally varies predictably with regional variations in hydrogeology. Abundant nonpoint (primarily agricultural) sources and hydrogeologic conditions, for example, contribute to particularly large base-flow flux from the Delmarva Peninsula to Chesapeake Bay. In the Delmarva Peninsula part of the Chesapeake Watershed, more than 10 percent of total nonpoint nitrogen applications is transported through groundwater to stream base flow

  2. Effects of climate change and agricultural adaptation on nutrient loading from Finnish catchments to the Baltic Sea.

    PubMed

    Huttunen, Inese; Lehtonen, Heikki; Huttunen, Markus; Piirainen, Vanamo; Korppoo, Marie; Veijalainen, Noora; Viitasalo, Markku; Vehviläinen, Bertel

    2015-10-01

    Climate change is expected to increase annual and especially winter runoff, shorten the snow cover period and therefore increase both nutrient leaching from agricultural areas and natural background leaching in the Baltic Sea catchment. We estimated the effects of climate change and possible future scenarios of agricultural changes on the phosphorus and nitrogen loading to the Baltic Sea from Finnish catchments. In the agricultural scenarios we assumed that the prices of agricultural products are among the primary drivers in the adaptation to climate change, as they affect the level of fertilization and the production intensity and volume and, hence, the modeled changes in gross nutrient loading from agricultural land. Optimal adaptation may increase production while supporting appropriate use of fertilization, resulting in low nutrient balance in the fields. However, a less optimal adaptation may result in higher nutrient balance and increased leaching. The changes in nutrient loading to the Baltic Sea were predicted by taking into account the agricultural scenarios in a nutrient loading model for Finnish catchments (VEMALA), which simulates runoff, nutrient processes, leaching and transport on land, in rivers and in lakes. We thus integrated the effects of climate change in the agricultural sector, nutrient loading in fields, natural background loading, hydrology and nutrient transport and retention processes.

  3. Dendrogeomorphic approaches for identifying the probable occurrence of debris flows and related torrential processes in steep headwater catchments: The Hrubý Jeseník Mountains, Czech Republic

    NASA Astrophysics Data System (ADS)

    Tichavský, Radek; Šilhán, Karel

    2015-10-01

    Culminating parts of mid-mountain ranges in Central Europe are interwoven by a network of high-gradient streams. These parts, together with the surrounding slopes, form a coupling system in which hazardous geomorphic processes, such as landslides, debris flows or flash floods, can occur. In the case of the Hrubý Jeseník Mountains (Eastern Sudetes, Czech Republic), we present an evaluation of the debris flows and related torrential processes in the high-gradient streams of the selected catchment based on dendrogeomorphic methods. In addition to the classical dendrogeomorphic approaches we refined the procedure of identifying certain and probable events using new weighted indexes for event reconstruction. Additionally, because of the steep narrow channels without a characteristic accumulation cone, a new spatial approach is defined based on the spacing of disturbed trees for each event (random distribution or clustering) and location of disturbed trees in an individual section of the valley floor. Using Kernel Density analysis for each event and calculating the particular grids in ArcGIS software, we are able to describe the spatial reach and probable nature of an event (debris flow or hyperconcentrated flow). Dendrogeomorphic analysis of 397 sampled trees (predominantly coniferous trees) revealed 24 torrential events (15 certain, nine probable) since 1928 with peaks in 1991, 1997 and 2010 according to index values. In addition, the spatial distribution of disturbed trees (grouped in clusters) in these years indicates debris flow events in the upper parts of the catchment. It seems that new dendrogeomorphic approaches should be valuable in remote, steep headwater catchments where several types of processes affect the valley floors.

  4. Homogenization of Spatial Patterns of Hydrologic Response in Artificially Drained Agricultural Catchments

    NASA Astrophysics Data System (ADS)

    Boland, S. J.; Basu, N. B.; Schilling, K.

    2013-12-01

    Anthropogenic modifications to the landscape, with agricultural activities being a primary driver, have resulted in significant alterations to the hydrologic cycle. Artificial drainage, including surface and subsurface drainage (tile drains), is one of the most extensive manipulations in agricultural landscapes and thus is expected to provide a distinct signature of anthropogenic modification. This study adopts a data synthesis approach in an effort to characterize the signature of artificial subsurface drainage. Daily discharge data from 24 basins across the state of Iowa, which encapsulate a range of anthropogenic modifications, are assessed using a variety of flow metrics. Results indicate that the presence of artificial subsurface drainage leads to a homogenization of landscape hydrologic response. Non-tiled watersheds exhibit a decrease in the area-normalized peak discharge and an increase in the baseflow ratio (baseflow/streamflow) with increases in the spatial scale, while scale invariance is apparent in tiled basins. Within-basin variability in hydrograph recession coefficients also appears to decrease with increases in the proportion of the catchment that is artificially drained. Finally, the differences between tiled and non-tiled landscapes disappear at scales greater than approximately 2200 km2, indicating that this may be a threshold scale for studying the effects of tile drainage. This decrease in within-basin variability and the scale invariance of hydrologic metrics in artificially drained watersheds are attributed to the creation of a bypass flow hydrologic pathway that bypasses the complexity of the catchment travel paths. Spatial homogeneity in responses implies that it may be possible to develop more parsimonious hydrologic models for these regions.

  5. Sediment transport in headwaters of a volcanic catchment—Kamchatka Peninsula case study

    NASA Astrophysics Data System (ADS)

    Chalov, Sergey R.; Tsyplenkov, Anatolii S.; Pietron, Jan; Chalova, Aleksandra S.; Shkolnyi, Danila I.; Jarsjö, Jerker; Maerker, Michael

    2017-01-01

    Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9•104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model-modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.

  6. Legacies and Trajectories of Hormone Export from Agricultural Catchments Under Natural and Anthropogenic Drivers

    NASA Astrophysics Data System (ADS)

    Gall, H. E.; Mashtare, M. L.; Sassman, S. A.; Rao, P. C.; Thompson, S. E.; Basu, N. B.; Lee, L. S.

    2011-12-01

    Hormones and other emerging contaminants have been detected in surface waters worldwide at concentrations known to negatively impact sensitive aquatic species. Concentrated animal feeding operations (CAFOs) are a significant source of hormones to the environment, as their recent intensification has increased manure production and land disposal. However, little is known regarding the short- and long-term fate and transport in catchments and likely environmental impacts. Lab microcosm and column studies indicate moderately high retardation (log KOC ~ 2.8 - 3.7) and fast aerobic biotransformation (half-lives < 10 days), yet monitoring reveals consistent presence of hormones in streams. Field studies at nested scales in tile-drained agricultural catchments suggested time-invariant concentrations for hormone export at annual time scales, similar to that noted for nutrients, implying accumulation of legacy stores from annual manure applications. A robust hydro-biogeochemical model, Hormone Export and Restoration Dynamics (HERD), was developed and validated to probe several research questions: (i) can manure application practices lead to the accumulation of hormones within the soil profile and develop legacy sources?; (ii) how persistent are hormones when long-term manure applications cease?; and (iii) to what extent can best management practices be successfully employed to reduce the downstream export of hormones? Preliminary HERD simulations suggest that hormones build up in the soil profile over time as a result of repeated animal waste applications, creating legacy sources that cause hormone export to become mass transfer-limited rather than source-limited. Under such conditions, annual flow-weighted concentrations were found to be chemostatic, implying hydrologic variability rather than biogeochemical processes as the dominant control of hormone export. Additionally, these results suggest that long-term, repeated animal waste applications can lead to chronic exposure

  7. Uncertainty assessments and hydrological implications of climate change in two adjacent agricultural catchments of a rapidly urbanizing watershed.

    PubMed

    Oni, S K; Futter, M N; Molot, L A; Dillon, P J; Crossman, J

    2014-03-01

    Lake Simcoe is the most important inland lake in Southern Ontario. The watershed is predominantly agricultural and under increasing pressure from urbanization, leading to changing runoff patterns in rivers draining to the lake. Uncertainties in rainfall-runoff modeling in tributary catchments of the Lake Simcoe Watershed (LSW) can be an order of magnitude larger than pristine watersheds, hampering water quality predictions and export calculations. Here we conduct a robust assessment to constrain the uncertainty in hydrological simulations and projections in the LSW using two representative adjacent agricultural catchments. Downscaled CGCM 3 projections using A1B and A2 emission scenarios projected increases of 4°C in air temperature and a 26% longer growing season. The fraction of precipitation falling as snow will decrease. Spring runoff is an important event in LSW but individual HBV best calibrated parameter sets under-predicted peak flows by up to 32%. Using an ensemble of behavioral parameter sets achieved credible representations of present day hydrology and constrained uncertainties in future projections. Parameter uncertainty analysis showed that the catchments differ in terms of their snow accumulation/melt and groundwater dynamics. Human activities exacerbate the differences in hydrological response. Model parameterization in one catchment could not generate credible hydrological simulations in the other. We cautioned against extrapolating results from monitored to ungauged catchments in managed watersheds like the LSW.

  8. Effect of policy-induced measures on suspended sediments and total phosphorus concentrations from three Norwegian agricultural catchments.

    PubMed

    Bechmann, Marianne; Stålnacke, Per

    2005-05-15

    In Norway, agricultural subsidies have, since the late 1980s, been targeted to reduce soil erosion, transfer of soil particles and phosphorus (P) losses. The subsidies led to, e.g., a fourfold increase in the area not ploughed from 1991 to 2001 and a reduced P fertiliser consumption by 60%, especially in areas with high livestock density. Moreover, in the late 1980s agricultural point sources of P from storage facilities of manure and fodder were reduced. In this paper, we evaluate the effect of these policy-induced measures and changed agricultural practices on suspended sediment (SS) and total P (TP) concentrations in three agricultural catchments (1, 3 and 87 km2). Results from the statistical trend analyses for the study period (14-17 years) showed weak, but statistically significant (p<0.05), downward trends in concentrations of TP and SS in the two streams with a high initial TP or SS concentration. In the stream with low initial concentrations of TP and SS, however, no statistically significant trends were shown. The stream with the highest initial concentration of SS showed a statistically significant downward trend in both TP and SS concentrations. The catchment with low initial concentration of SS and medium livestock density showed no detectable trends, while the catchment with high livestock density and low concentrations of SS in the stream showed a statistically significant downward trend in TP concentrations. The results from this study suggest that subsidies and mitigation measures can reduce concentrations of TP and SS in streamwater in highly polluted catchments, although the reduction is small compared to the variations between catchments.

  9. Nitrate attenuation in agricultural catchments: Shifting balances between transport and reaction

    NASA Astrophysics Data System (ADS)

    Ocampo, Carlos J.; Oldham, Carolyn E.; Sivapalan, Murugesu

    2006-01-01

    Simultaneous observations, across multiple spatial and temporal scales, are needed to understand the complex interactions between hydrological and biogeochemical processes in catchments and the primary controls on NO3- availability and mobility. This paper addresses these issues by using data collected from a detailed field experiment, carried out on two topographically different hillslopes (one steep and the other flat) located within an agricultural catchment in Western Australia. Continuous hydrometric data and measurements of chemical tracers, geochemical parameters, and NO3- concentrations taken from the shallow perched aquifer across riparian, midslope, and upland locations were analyzed and interpreted through a simple process-based numerical model of transport and reaction. The NO3- concentration data indicated that the temporal and spatial patterns of NO3- concentrations within the hillslopes are linked to the state of hydrological connectivity of the three landscape units as the shallow perched aquifer developed during the winter. Significant NO3- attenuation occurs within the riparian zones after the transport of NO3- from midslope sources begins. Application of a mixing model, which partitions the riparian zones into three water source components, and the numerical model of NO3- transport and reaction indicates that different mechanisms, dilution in the steep hillslope and denitrification in the flat hillslope, are responsible for much of the observed NO3- attenuation in the riparian zones. In this way, this work highlights the importance of hillslope topography in determining the relative roles of transport and reaction in NO3- attenuation and export from riparian zones. The experimental results also supported the use of the Damköhler number, a simple dimensionless number that is a measure of the competition between transport and reaction processes, which allowed a favorable comparison of our findings with previous results published in the literature

  10. Scaling issues relating to phosphorus transfer from land to water in agricultural catchments

    NASA Astrophysics Data System (ADS)

    Brazier, R. E.; Heathwaite, A. L.; Liu, S.

    2005-03-01

    Various scales of input data exist to parameterise diffuse pollution models for the UK. For screening methodologies such as the phosphorus indicators tool—PIT [Heathwaite, A.L., Sharpley, A.N., Bechmann, M., 2003a. The conceptual basis for a decision support framework to assess the risk of phosphorus loss at the field scale across Europe. Journal of Plant Nutrition and Soil Science 166, 1-12; Heathwaite, A.L., Burke, S., Quinn, P.F., 2003b. The nutrient export risk matrix (the NERM) for strategic application of biosolids to agricultural land. International Association for Hydrological Sciences Publication 285, 1-9], which is applied throughout England and Wales, some assessment of the implications of using input data derived at different scales must be made. This work is further driven by practical issues such as licensing costs and data availability, which mean that not all data are readily accessible for all end users. This paper represents a first step towards quantifying the 'value-added' to model predictions by using input data derived at three different scales: 50×50 m, 1×1 km and 5×5 km. Model runs using PIT were carried out against observed phosphorus water quality data from the River Start and River Gara, which are the main sub-catchments of Slapton Ley, a grade 1 National Nature Reserve in southwest England. Model runs for the main 46 km 2 Slapton catchment were also undertaken. The results show that some improvement in the ability of the model to capture the observed water quality behaviour may be made by using higher resolution DEM data, though these improvements may be outweighed by the extra data processing and computational time. Conversely, model runs driven by the 5 km data demonstrate consistent under-prediction for all three test catchments, which is perhaps not surprising given the greater degree of averaging underlying datasets at this scale. Results from the 1 km datasets provide the best agreement with observed water quality data, and

  11. Modeling climate change impact on surface runoff, erosion and sediment yield in agriculturally used catchments

    NASA Astrophysics Data System (ADS)

    Scherer, Ulrike; Gerlinger, Kai; Zehe, Erwin

    2010-05-01

    Surface runoff and soil erosion as well as many of the factors controlling both will be directly or indirectly affected by climate change impact. Increasing precipitation amounts and intensities cause non linear responses of runoff and soil loss. The variation of local precipitation and temperature regimes implicate shifts in vegetation cover, soil conditions, land use and management which will affect runoff, erosion and the translocation of sediments and environmental pollutants to surface waters. For example the adaptation of crop rotation and planting dates due to changes within temperature regimes will cause shifts in vegetation cover which might affect erosion due to decreasing cover in periods of high storm risk. In agriculturally used catchments of Southern Germany, the susceptibility of soils to erosion is highest during spring and summer because of both, an increasing risk for thunderstorms in this season and a sparse soil cover due to the growth period of crops. Climate change scenarios for Southern Germany assume higher average precipitation rates during the winter half year, whereas precipitation rates in summer are slightly decreasing. Longer lasting rainfall events in winter will increase runoff but will have no significant impact on sediment yields, since the rainfall intensities are quite low. Despite lower rainfall rates in the summer half year it is expected that the rainfall intensity of extreme events will increase, including a higher risk for erosion. To analyse how surface runoff response and sediment yields will be affected by climate change impact the process based erosion model CATFLOW-SED was used. CATFLOW-SED is based on Richards Equation including an effective approach for preferential flow and the Saint-Venant-Equation to simulate soil water dynamics and overland flow / river flow. The erosion process is modeled using shear stress, the momentum balance of precipitation and a semi-empirical erosion resistance for predicting soil

  12. Understanding the controls on deposited fine sediment in the streams of agricultural catchments.

    PubMed

    Naden, P S; Murphy, J F; Old, G H; Newman, J; Scarlett, P; Harman, M; Duerdoth, C P; Hawczak, A; Pretty, J L; Arnold, A; Laizé, C; Hornby, D D; Collins, A L; Sear, D A; Jones, J I

    2016-03-15

    Excessive sediment pressure on aquatic habitats is of global concern. A unique dataset, comprising instantaneous measurements of deposited fine sediment in 230 agricultural streams across England and Wales, was analysed in relation to 20 potential explanatory catchment and channel variables. The most effective explanatory variable for the amount of deposited sediment was found to be stream power, calculated for bankfull flow and used to index the capacity of the stream to transport sediment. Both stream power and velocity category were highly significant (p ≪ 0.001), explaining some 57% variation in total fine sediment mass. Modelled sediment pressure, predominantly from agriculture, was marginally significant (p<0.05) and explained a further 1% variation. The relationship was slightly stronger for erosional zones, providing 62% explanation overall. In the case of the deposited surface drape, stream power was again found to be the most effective explanatory variable (p<0.001) but velocity category, baseflow index and modelled sediment pressure were all significant (p<0.01); each provided an additional 2% explanation to an overall 50%. It is suggested that, in general, the study sites were transport-limited and the majority of stream beds were saturated by fine sediment. For sites below saturation, the upper envelope of measured fine sediment mass increased with modelled sediment pressure. The practical implications of these findings are that (i) targets for fine sediment loads need to take into account the ability of streams to transport/retain fine sediment, and (ii) where agricultural mitigation measures are implemented to reduce delivery of sediment, river management to mobilise/remove fines may also be needed in order to effect an improvement in ecological status in cases where streams are already saturated with fines and unlikely to self-cleanse.

  13. Patterns and processes of nutrient transfers from land to water: a catchment approach to evaluate Good Agricultural Practice in Ireland

    NASA Astrophysics Data System (ADS)

    Mellander, P.-E.; Melland, A. R.; Shortle, G.; Wall, D.; Mechan, S.; Buckley, C.; Fealy, R.; Jordan, P.

    2009-04-01

    Eutrophication of fresh, transitional and coastal waters by excessive nutrient inputs is one of the most widespread water quality problems in developed countries. Sources of nutrient nitrogen (N) and phosphorus (P) can come from a multiplicity of sources and be dependent on numerous hydrological controls from catchments with both urban and agricultural landuses. Aquatic impacts are widely reported as a result of excessive nutrient transfers from land to water and include changes in ecological integrity and loss of amenity. In the European Union, the Water Framework Directive (WFD) and associated Directives are the key structures with which member states must develop national and often trans-national polices to deal with issues of water resources management. The linked Nitrates Directive is particularly concerned with integrating sustainable agriculture and good water quality objectives and is written into national polices. In Ireland this policy is the Nitrates Directive National Action Programme (NAP), Statutory Instruction 378, Good Agricultural Practise regulation, and amongst other things, sets targets and limits on the use of organic and inorganic fertilisers, soil fertility and slurry/fertiliser spreading and cultivation times. To evaluate the effectiveness of this policy, Teagasc, the Irish Agriculture and Food Development Authority, is undertaking a catchment scale audit on sources, sinks, and changes in nutrient use and export over several years. The Agricultural Catchments Programme is based on a science-stakeholder-management partnership to generate knowledge and specifically to protect water quality from nitrogen and phosphorus transfers within the constraints of the requirements of modern Irish agricultural practises. Eight catchments of 5-12 km2 have been selected for the programme to represent a range of agricultural intensities and vulnerabilities to nitrogen and phosphorus loss including catchments that are situated on permeable and impermeable

  14. Catchments Under Change: Assessing Impacts and Feedbacks from New Biomass Crops in the Agricultural Midwestern USA

    NASA Astrophysics Data System (ADS)

    Yaeger, Mary; Housh, Mashor; Ng, Tze Ling; Cai, Ximing; Sivapalan, Murugesu

    2013-04-01

    In order to meet the challenges of future change, it is essential to understand the environmental response to current conditions and historical changes. The central Midwestern US is an example of anthropogenic change and environmental feedbacks, having been transformed from a natural grassland system to an artificially-drained agricultural system. Environmental feedbacks from reduced soil residence times coupled with increasing crop fertilization have manifested as a hypoxic zone in the Gulf of Mexico. In an effort to address these feedbacks while meeting new crop demands, large-scale planting of high-yielding perennial biomass crops has been proposed. This could be detrimental to both human and environmental streamflow users because these plants require more water than do current crops. The lowest natural flows in this shallow groundwater-dependent region coincide with the peak of the growing season, thus compounding the problem. Therefore, for large-scale biomass crop production to be sustainable, these tradeoffs between water quality and water quantity must be fully understood. To better understand the catchment response to current conditions, we have analyzed streamflow data in a central Illinois agricultural watershed. To deal with future changes, we have developed an integrated systems model which provides, among other outputs, the land usage that maximizes the benefit to the human system. This land use is then implemented in a separate hydrologic model to determine the impact to the environmental system. Interactively running the two models, taking into account the catchment response to human actions as well as possible anthropogenic responses to the environment, allows us to examine the feedbacks between the two systems. This lets us plot the trajectory of the state of the system, which we hypothesize will show emergent internal properties of the coupled system. Initial tests of this modeling framework show promise that this may indeed be the case. External

  15. Assessing the impacts of sustainable agricultural practices for water quality improvements in the Vouga catchment (Portugal) using the SWAT model.

    PubMed

    Rocha, João; Roebeling, Peter; Rial-Rivas, María Ermitas

    2015-12-01

    The extensive use of fertilizers has become one of the most challenging environmental issues in agricultural catchment areas. In order to reduce the negative impacts from agricultural activities and to accomplish the objectives of the European Water Framework Directive we must consider the implementation of sustainable agricultural practices. In this study, we assess sustainable agricultural practices based on reductions in N-fertilizer application rates (from 100% to 0%) and N-application methods (single, split and slow-release) across key agricultural land use classes in the Vouga catchment, Portugal. The SWAT model was used to relate sustainable agricultural practices, agricultural yields and N-NO3 water pollution deliveries. Results show that crop yields as well as N-NO3 exportation rates decrease with reductions in N-application rates and single N-application methods lead to lower crop yields and higher N-NO3 exportation rates as compared to split and slow-release N-application methods.

  16. A review of monitoring approaches and outcomes of surface water quality mitigation measures in meso-scale agricultural catchments

    NASA Astrophysics Data System (ADS)

    Melland, Alice; Jordan, Phil; Murphy, Paul; Mellander, Per-Erik; Shortle, Ger

    2013-04-01

    Critical for an informative feedback loop from scientific monitoring of biophysical change, to making and implementing suitable policy to effect the desired change, are both accurate measurement of biophysical change, and measurement or modelling of the causes of change. For example the European Environment Agency uses the DPSIR framework to assess change in the state (S) of natural resources due to changes in specific drivers (D) and pressures (P) that can have an impact (I) and are the focus of policy responses (R). This paper provides a review of meso-catchment scale studies worldwide that have measured the impacts of agricultural land management practice on surface water quality. Approaches for measuring water quality impacts of agricultural mitigation practices in meso-catchments (1-100 km2) ranged from measuring water quality over a time series, such as before and after a land management change, or over a spatial series such as in paired catchments with and without agricultural practice change (or over a gradient of practices or catchment types), and by cause and effect studies that measure sources, pathways and impacts of practices. Agricultural mitigation measures had no measurable effect, or positive, or negative effects on water quality over periods of 3 to 20 years. In most catchments where beneficial effects of mitigation measures were successfully measured, combinations of measures that address nutrient or pollutant sources, pathways, delivery and impact have been implemented. Successful farm measures included substantial reductions in the intensity of the farming systems, improved engineering and crop management to reduce runoff and drainage transport of nutrients and sediment, as well as high rates of implementation of measures across the catchments. In many cases, the potential to measure improvement in one or more water quality indicators was limited by the impact of a few management or weather events. Reasons that water quality did not improve in

  17. Long-term field-scale experiment on using lime filters in an agricultural catchment.

    PubMed

    Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo

    2012-01-01

    The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt lime (CaO) or spent lime [CaO, Ca(OH), and CaCO]. Easily soluble lime results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both filter parts removed PTOT and SS efficiently from the water; the burnt-lime part also removed DRP. The mixed-lime part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating lime can be used together with buffer zones to reduce both P and SS load to watercourses.

  18. Influence of grass filter strips on structure and function of riparian habitats of agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grass filter strips are a widely used conservation practice in the United States for reducing nutrient, pesticide, and sediment loadings into agricultural streams. Previous studies have documented the effectiveness of grass filter strips in reducing the input of agricultural pollutants, but the inf...

  19. USE OF MACROINVERTEBRATE METRICS TO DIFFERENTIATE BETWEEN THE EFFECTS OF DECREASED CANOPY AND INCREASED EMBEDDEDNESS IN STREAMS IN DRAINING AGRICULTURAL CATCHMENTS

    EPA Science Inventory

    Reduced canopy as a result of lost riparian vegetation and increased substrate embeddedness as a result of greater inputs of the fine sediments are two environmental stressor gradients that often covary in streams draining agricultural catchments. An understanding of relationship...

  20. Using lumped modelling for providing simple metrics and associated uncertainties of catchment response to agricultural-derived nitrates pollutions

    NASA Astrophysics Data System (ADS)

    RUIZ, L.; Fovet, O.; Faucheux, M.; Molenat, J.; Sekhar, M.; Aquilina, L.; Gascuel-odoux, C.

    2013-12-01

    The development of simple and easily accessible metrics is required for characterizing and comparing catchment response to external forcings (climate or anthropogenic) and for managing water resources. The hydrological and geochemical signatures in the stream represent the integration of the various processes controlling this response. The complexity of these signatures over several time scales from sub-daily to several decades [Kirchner et al., 2001] makes their deconvolution very difficult. A large range of modeling approaches intent to represent this complexity by accounting for the spatial and/or temporal variability of the processes involved. However, simple metrics are not easily retrieved from these approaches, mostly because of over-parametrization issues. We hypothesize that to obtain relevant metrics, we need to use models that are able to simulate the observed variability of river signatures at different time scales, while being as parsimonious as possible. The lumped model ETNA (modified from[Ruiz et al., 2002]) is able to simulate adequately the seasonal and inter-annual patterns of stream NO3 concentration. Shallow groundwater is represented by two linear stores with double porosity and riparian processes are represented by a constant nitrogen removal function. Our objective was to identify simple metrics of catchment response by calibrating this lumped model on two paired agricultural catchments where both N inputs and outputs were monitored for a period of 20 years. These catchments, belonging to ORE AgrHys, although underlain by the same granitic bedrock are displaying contrasted chemical signatures. The model was able to simulate the two contrasted observed patterns in stream and groundwater, both on hydrology and chemistry, and at the seasonal and pluri-annual scales. It was also compatible with the expected trends of nitrate concentration since 1960. The output variables of the model were used to compute the nitrate residence time in both the

  1. Quantifying sediment sources in a lowland agricultural catchment pond using (137)Cs activities and radiogenic (87)Sr/(86)Sr ratios.

    PubMed

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J Patrick; Salvador-Blanes, Sébastien; Thil, François; Dapoigny, Arnaud; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

    2016-10-01

    Soil erosion often supplies high sediment loads to rivers, degrading water quality and contributing to the siltation of reservoirs and lowland river channels. These impacts are exacerbated in agricultural catchments where modifications in land management and agricultural practices were shown to accelerate sediment supply. In this study, sediment sources were identified with a novel tracing approach combining cesium ((137)Cs) and strontium isotopes ((87)Sr/(86)Sr) in the Louroux pond, at the outlet of a lowland cultivated catchment (24km(2), Loire River basin, France) representative of drained agricultural areas of Northwestern Europe. Surface soil (n=36) and subsurface channel bank (n=17) samples were collected to characterize potential sources. Deposited sediment (n=41) was sampled across the entire surface of the pond to examine spatial variation in sediment deposits. In addition, a 1.10m sediment core was sampled in the middle of the pond to reconstruct source variations throughout time. (137)Cs was used to discriminate between surface and subsurface sources, whereas (87)Sr/(86)Sr ratios discriminated between lithological sources. A distribution modeling approach quantified the relative contribution of these sources to the sampled sediment. Results indicate that surface sources contributed to the majority of pond (μ 82%, σ 1%) and core (μ 88%, σ 2%) sediment with elevated subsurface contributions modeled near specific sites close to the banks of the Louroux pond. Contributions of the lithological sources were well mixed in surface sediment across the pond (i.e., carbonate sediment contribution, μ 48%, σ 1% and non-carbonate sediment contribution, μ 52%, σ 3%) although there were significant variations of these source contributions modeled for the sediment core between 1955 and 2013. These fluctuations reflect both the progressive implementation of land consolidation schemes in the catchment and the eutrophication of the pond. This original sediment

  2. Monitoring Two Small Catchments to Evaluate Effects of No-Tillage Agricultural Management in São Paulo State, Brazil

    NASA Astrophysics Data System (ADS)

    Figueiredo, R. D. O.; Gonçalves, A. O.; Melo, A. D. S.; de Bona, F. D.; Hernani, L. C.

    2015-12-01

    In recent years, declines in water and soil quality have been observed in areas of Brazil where no-till agriculture had been previously implemented. Poor soil management associated with the absence of public policies has caused soil erosion, because many farmers are moving back from no-till to traditional cultivation for faster economic gains. A research project - SoloVivo Project - leaded by Embrapa (Brazilian Agricultural Research Corporation) in partnership with Itaipu Binacional aims to develop and validate, in a participatory way, tools to evaluate the technical performance of soil and water management at the rural properties that practice no-till agriculture. In this context we have selected two paired small (< 100 ha) catchments in the Paranapanema region, São Paulo State, where no-till management is practiced at two different degrees of effectiveness. In the figure bellow it can be seen a scene of one of the two studied catchments. For monitoring rainfall, soil solution and stream water, each catchment will be equipped with a programmable datalogger (with cell phone communication for data collection) linked to: a high intensity tipping bucket rain gage; a reflectometer to monitor soil volumetric water content, bulk electric conductivity and temperature; a radar water level sensor; a turbidity sensor; and an electric conductivity-temperature probe. We expect that stream flow and sediment generation, besides water quality (measured by conductivity) may serve as indicators of the benefits of no-tillage agriculture done more or less well. The results of this study will be used to stimulate discussions at workshops with the farmers who participate in a rural producers association in the region. In addition this and other results can be used to help the Brazilian National Water Agency (ANA) decide about applying no-till agricultural management systems in its programs of payment for environmental services.

  3. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; methods of data collection and analysis and description of study areas

    USGS Publications Warehouse

    Chichester, Douglas C.

    1988-01-01

    The U.S. Geological Survey is conducting a water quality study as part of the nationally implemented Rural Clean Water Program in the headwaters of the Conestoga River, Pennsylvania. The study, which began in 1982, was designed to determine the effect of agricultural best management practices on surface--and groundwater quality. The study was concentrated in four areas within the intensively farmed, carbonate rock terrane located predominately in Lancaster County, Pennsylvania. These areas were divided into three monitoring components: (1) a Regional study area (188 sq mi): (2) a Small Watershed study area (5.82 sq mi); and (3) two field site study areas, Field-Site 1 (22.1 acres) and Field 2 (47.5 acres). The type of water quality data and the methods of data collection and analysis are presented. The monitoring strategy and description of the study areas are discussed. The locations and descriptions for all data collection locations at the four study areas are provided. (USGS)

  4. Spatio-temporal analysis of discharge regimes based on hydrograph classification techniques in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Chen, Xiaofei; Bloeschl, Guenter; Blaschke, Alfred Paul; Silasari, Rasmiaditya; Exner-Kittridge, Mike

    2016-04-01

    The stream, discharges and groundwater hydro-graphs is an integration in spatial and temporal variations for small-scale hydrological response. Characterizing discharges response regime in a drainage farmland is essential to irrigation strategies and hydrologic modeling. Especially for agricultural basins, diurnal hydro-graphs from drainage discharges have been investigated to achieve drainage process inferences in varying magnitudes. To explore the variability of discharge responses, we developed an impersonal method to characterize and classify discharge hydrograph based on features of magnitude and time-series. A cluster analysis (hierarchical k-means) and principal components analysis techniques are used for discharge time-series and groundwater level hydro-graphs to analyze their event characteristics, using 8 different discharge and 18 groundwater level hydro-graphs to test. As the variability of rainfall activity, system location, discharge regime and soil moisture pre-event condition in the catchment, three main clusters of discharge hydro-graph are identified from the test. The results show that : (1) the hydro-graphs from these drainage discharges had similar shapes but different magnitudes for individual rainstorm; the similarity is also showed in overland flow discharge and spring system; (2) for each cluster, the similarity of shape insisted, but the rising slope are different due to different antecedent wetness condition and the rain accumulation meanwhile the difference of regression slope can be explained by system location and discharge area; and (3) surface water always has a close proportional relation with soil moisture throughout the year, while only after the soil moisture exceeds a certain threshold does the outflow of tile drainage systems have a direct ratio relationship with soil moisture and a inverse relationship with the groundwater levels. Finally, we discussed the potential application of hydrograph classification in a wider range of

  5. Mitigation scenario analysis: modelling the impacts of changes in agricultural management practices on surface water quality at the catchment scale

    NASA Astrophysics Data System (ADS)

    Taylor, Sam; He, Yi; Hiscock, Kevin

    2014-05-01

    Increasing human pressures on the natural environment through the demand for increased agricultural productivity have exacerbated and deteriorated water quality conditions within many environments due to an unbalancing of the nutrient cycle. As a consequence, increased agricultural diffuse water pollution has resulted in elevated concentrations of nutrients within surface water and groundwater bodies. This deterioration in water quality has direct consequences for the health of aquatic ecosystems and biodiversity, human health, and the use of water as a resource for public water supply and recreation. To mitigate these potential impacts and to meet commitments under the EU Drinking Water and Water Framework Directives, there is a need to improve our understanding of the impacts that agricultural land use and management practices have on water quality. Water quality models are one of the tools available which can be used to facilitate this aim. These simplified representations of the physical environment allow a variety of changes to be simulated within a catchment, including for example changes in agricultural land use and management practices, allowing for predictions of the impacts of those measures on water quality to be developed and an assessment to be made of their effectiveness in improving conditions. The aim of this research is to apply the water quality model SWAT (Soil and Water Assessment Tool) to the Wensum catchment (area 650 km2), situated in the East of England, to predict the impacts of potential changes in land use and land management practices on water quality as part of a process to select those measures that in combination will have the greatest potential to improve water quality. Model calibration and validation is conducted at three sites within the catchment against observations of river discharge and nitrate and total phosphorus loads at a monthly time-step using the optimisation algorithm SUFI-2 (Sequential Uncertainty Fitting Version 2

  6. Recent trends in water quality in an agricultural catchment in Eastern Scotland: elucidating the roles of hydrology and land use.

    PubMed

    Dunn, S M; Sample, J; Potts, J; Abel, C; Cook, Y; Taylor, C; Vinten, A J A

    2014-07-01

    Across the EU, programmes of measures have been introduced as part of river basin management planning as a means of tackling problems of diffuse pollution from agriculture. Evidence is required to demonstrate the effectiveness of these measures and with this overarching objective, monitoring of an agricultural catchment in Eastern Scotland was initiated in 2007. As a precursor to evaluating the effect of new management measures it is essential to understand how other factors, including hydrology and land use changes, could have influenced water quality. This study undertook an analysis of the trends in concentrations and loads of nitrate, soluble reactive phosphorus (SRP), suspended solids (SS) and turbidity measured at six points in the catchment over a six year period. The results identified both differing trends between determinands and differing trends occurring over varying spatial scales. The only direct relationships between land use and water quality that could be identified based on annual data was a positive link between arable cropping and nitrate concentrations. At the sub-catchment scale some temporal changes in land use and management explained short-term trends in nitrate but not in SRP. Lags in the system were identified due to soil adsorption, in-stream/loch processing and groundwater transport making the identification of cause and effect problematic. The results have implications for the demonstration of effectiveness of measures over the shorter term and the timescales of recovery from diffuse pollution. Longer term monitoring at small scales will be important in this regard.

  7. The fate of organic carbon in colluvial soils in a subtropical agricultural catchment (Arvorezinha, Brazil)

    NASA Astrophysics Data System (ADS)

    Van de Broek, Marijn; Van Oost, Kristof; Minella, Jean; Govers, Gerard

    2016-04-01

    One of the main reasons as to why soil erosion is considered to be a carbon sink for the atmosphere is that eroded carbon is often redeposited and buried in depositional environments. However, the quantification of the magnitude of this effect is still uncertain because the residence time of soil organic carbon in depositional environments is ill defined. The latter is especially true for tropical and subtropical areas as field data for these climatic zones are largely lacking. This is an important hiatus as ca. 40% of the total global arable land is located in the (sub-)tropics [1]. We collected samples from four depositional and one stable agricultural profile in a small agricultural catchment in Arvorezinha (Brazil) where deforestation started ca. 90 yrs ago. δ13C depth profiles allowed to identify the bottom of the original A-horizon: this is because δ13C values of the buried forest soils are significantly heavier than those of the colluvial deposits. The results show that soil organic carbon contents systematically decrease with depth below the actual plough layer. This is due to the fact that a significant fraction of the organic carbon that was originally deposited is removed by mineralization from these soils over decadal time scales. As the time of deforestation is known, age-depth curves could be established. Combining this information with SOC measurements allowed for a first estimate of carbon preservation rates and showed that after 70 years ca. 25% of the deposited organic carbon is released to the atmosphere: results were very consistent across profiles. In temperate environments, the time necessary for this fraction of the deposited carbon to be mineralized is somewhat longer, i.e. 100 years [2]. This suggests that soil organic carbon may be decomposed faster in sub-tropical environments in comparison to temperate environments. This is not unexpected, given the fact that average soil temperatures are higher and soils are, in this climate

  8. Influence of planting grass filter strips on the structure and function of riparian habitats of agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grass filter strips are strips of cool or warm season grasses planted adjacent to agricultural streams to reduce nutrient, pesticide, and sediment input. This conservation practice is the most frequently planted riparian buffer type in the United States. Previous studies have not evaluated how gra...

  9. Long-term trends in climate and hydrology in an agricultural headwater watershed of central Pennsylvania, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate change has emerged as a key issue facing agriculture and water resources in the US. Long-term (1968-2012) temperature, precipitation and streamflow data from a small (7.3 km2) watershed in east-central Pennsylvania was used to examine climatic and hydrologic trends in the context of recent c...

  10. Influence of Antecedent Hydrologic Conditions on Nitrate and Phosphorus Export from a Small Agricultural Catchment in Southern Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Macrae, M. L.; English, M. C.; Schiff, S. L.; Stone, M.

    2009-04-01

    The ability of the scientific community to quantify and predict discharge and nutrient transport in a range of settings is confounded by the effects of antecedent hydrologic conditions in upland areas. Previous work has empirically linked spatial variables such as land use, soil type, topography, and drainage characteristics to hydrochemical export from various landscapes (e.g. MCDOWELL et al., 2001; ARHEIMER and LIDEN, 2000; STAMM et al., 1998; JORDAN et al., 1997; WELSCH et al., 2001). However, the specific reasons why similar types of events produce different nutrient export patterns are poorly understood. Nutrient (nitrate, soluble and total phosphorus) transport from agricultural catchments is difficult to quantify and predict because of the influence of variable hydrologic flowpaths and their interaction with varying nutrient pools. This research examines the role of antecedent hydrologic conditions on stream discharge and nitrate (NO3-), soluble reactive phosphorus (SRP) and total phosphorus (TP) export from a small (2.7 km2) first-order agricultural catchment in Southern Ontario, Canada. During 59 events occurring over a two-year sampling period (year-round), runoff ratios ranged from 0-0.99). Runoff ratios increased throughout successive events as conditions became wetter although key indices of antecedent wetness such as water table position, pre-event streamflow and soil moisture did not yield predictive relationships. Nitrate, SRP and TP transport from the catchment increased with antecedent wetness during some periods but decreased with antecedent wetness during other periods. This variability appears to be linked to a combination of the position of water table before and during the event, as well as timing of fertilizer application. It is hypothesized that in general, wetter antecedent hydrologic conditions increase nutrient transport from the catchment by increasing macropore connectivity between surface soil horizons and tile drains, although this

  11. Comparing hydrological signatures of small agricultural catchments using uncertain data provided by a soft hydrological monitoring

    NASA Astrophysics Data System (ADS)

    Crabit, Armand; Colin, François

    2016-04-01

    Discharge estimation is one of the greatest challenge for every hydrologist as it is the most classical hydrological variable used in hydrological studies. The key lies in the rating curves and the way they were built: based on field measurements or using physical equations as the Manning-Strickler relation… However, as we all know, data and associated uncertainty deeply impact the veracity of such rating curves that could have serious consequences on data interpretation. And, of all things, this affects every catchment in the world, not only the gauged catchments but also and especially the poorly gauged ones that account for the larger part of the catchment of the world. This study investigates how to compare hydrological behaviour of 11 small (0.1 to 0.6 km2) poorly gauged catchments considering uncertainty associated to their rating curves. It shows how important the uncertainty can be using Manning equation and focus on its parameter: the roughness coefficient. Innovative work has been performed under controlled experimental conditions to estimate the Manning coefficient values for the different cover types observed in studied streams: non-aquatic vegetations. The results show that estimated flow rates using suitable roughness coefficients highly differ from those we should have obtained if we only considered the common values given in the literature. Moreover, it highlights how it could also affect all derived hydrological indicators commonly used to compare hydrological behaviour. Data of rainfall and water depth at a catchment's outlet were recorded using automatic logging equipment during 2008-2009. The hydrological regime is intermittent and the annual precipitation ranged between 569 and 727 mm. Discharge was then estimated using Manning's equation and channel cross-section measurements. Even if discharge uncertainty is high, the results show significant variability between catchment's responses that allows for catchment classification. It also

  12. Impact of agricultural practices on runoff and glyphosate peaks in a small vineyard catchment

    NASA Astrophysics Data System (ADS)

    Amiot, Audrey; La Jeunesse, Isabelle; Jadas-Hécart, Alain; Landry, David; Sourice, Stéphane; Communal, Pierre-Yves; Ballouche, Aziz

    2013-04-01

    The Layon River, a tributary of the Loire River, does frequently not comply with water quality standards because of pesticides. Vineyard is generally denounced. The aim of this project is to explain the transfer of pesticides during runoff events and its interaction with erosion. Pesticides and suspended particulate matter (SPM) concentrations are monitored at the outlet of the vineyards catchment each 2 minutes during floods to follow peaks. The results of three different hydrological years (2009, 2011, 2012) are exposed. The 2.2ha catchment is composed of two main vineyards plots managed by two independent farmers. Mean slopes are of 8% and can reach 40% in terraces. A gauging station has been installed at the end of the slope with a calibrated Venturi channel. The measurement station is composed of (a) an approach channel of 10 meters long for the establishment of a stable water surface, (b) a trapezoidal long-throated flume to assess the flow rate with the water level measured with (c) a bubbler sensor, (d) an automatic rain gauge, (e) an automatic sampler, (f) a modem and (g) a logosens OTT® data logger. 2009 was an average year, 2011 was particularly dry and 2012 particularly wet. Quantities of glyphosate applied were respectively 1087, 645 and 720g. Maximum discharges in the gauging station were 5, 12 and 25L.s-1. Minimum and maximum concentrations of glyphosate in runoff waters were 1-449.1 µg.L-1 in 2009, 0.62-13.6 µg.L-1 in 2011 and 0.1-3.7 µg.L-1 in 2012. Minimum and maximum concentrations of SPM were 14-1261mg.L-1 in 2009, 108- 6454 mg.L-1 in 2011 and 9-1541 mg.L-1 in 2012. While flows, quantities of glyphosate applied and peaks of concentrations observed in 2011 are more important in 2009, SPM generated in the runoff waters are lower than 2011 and 2012, even though 2012 has particularly been a wet year. Also, maximum runoff coefficients are 7% in 2009 and 2011 and 57% in 2012. In fact, this latest explains differences between years better than

  13. Trace Element Distribution in Stream Bed Sediments Within AN Agricultural Catchment of the Broadkill River Watershed, Delaware, USA

    NASA Astrophysics Data System (ADS)

    Oyewumi, O.; Schreiber, M. E.

    2011-12-01

    This project examined the impact of long-term litter application on the chemical signatures of trace metals (As, Cu, Zn,) and nutrient (P) in river sediments of the Broadkill River watershed within the Delmarva Peninsula, a region of intense poultry production. Twenty-seven (27) sediment samples were collected from Broadkill River drainage systems and analyzed for acid and soluble extractable elements as well as basic soil parameters such as particle size, organic matter and soluble salts. Results showed that concentrations of the trace elements in stream sediments are approximately log-normally distributed, with concentrations increasing from upstream headwaters to downstream reaches draining predominantly agricultural areas. Using GIS maps with overlays of hydrology and land use activity, correlations between the concentrations of As, Cu, Zn and P and agricultural activities within the watershed were examined. Results indicate positive correlation between the trace elements but the connection to specific regions of agricultural land use is not clearly defined. Trace elements were also positively correlated with percent of clay and silt particles, indicating partitioning of these elements to finer grain sizes. Calculations of element enrichment factors and the geoaccumulation index revealed that most of the sediment samples were not enriched in trace elements with respect to our reference samples. However, trace element concentrations in sediments increased downgradient, suggesting that they may be influenced by anthropogenic activities within the watershed.

  14. Investigating suspended sediment dynamics in contrasting agricultural catchments using ex situ turbidity-based suspended sediment monitoring

    NASA Astrophysics Data System (ADS)

    Sherriff, S. C.; Rowan, J. S.; Melland, A. R.; Jordan, P.; Fenton, O.; hUallachain, D. O.

    2015-08-01

    Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required, but can be expensive and technically challenging. Here, the performance of in situ turbidity sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). The in situ and ex situ installations gave comparable results when calibrated against storm-period, depth-integrated SS data, with total loads at Grassland B estimated at 12 800 and 15 400 t, and 22 600 and 24 900 t at Arable B, respectively. The absence of spurious turbidity readings relating to bankside debris around the in situ sensor and its greater security make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (78/659/EEC) guideline of 25 mg L-1, and the continuous hourly record demonstrated that exceedance occurred less than 12 % of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils. Well

  15. Identifying the controls of soil loss in agricultural catchments using ex situ turbidity-based suspended sediment monitoring

    NASA Astrophysics Data System (ADS)

    Sherriff, S. C.; Rowan, J. S.; Melland, A. R.; Jordan, P.; Fenton, O.; Ó'hUallacháin, D.

    2015-03-01

    Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required but can be expensive and technically challenging. Here, the performance of in situ turbidity-sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). Calibrated against storm-period depth-integrated SS data, both systems gave comparable results; using the ex situ and in situ methods respectively, total load at Grassland B was estimated at 128 ± 28 and 154 ± 35, and 225 ± 54 and 248 ± 52 t at Arable B. The absence of spurious turbidity peaks relating to bankside debris around the in situ sensor and its greater security, make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (FFD) guideline of 25 mg L-1, and the continuous hourly record demonstrated that exceedance occurred less than 12% of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly-drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils

  16. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; a summary report, 1982-90

    USGS Publications Warehouse

    Lietman, Patricia L.

    1997-01-01

    Pipe-outlet terracing was effective in reducing sediment losses from a field site, but total nitrogen and phosphorus losses with runoff were not significantly different before and after terracing. Median concentrations of dissolved nitrate in several ground-water sampling locations increased after terrace installation. Dissolved nitrate concentrations in ground water decreased significantly after nutrient-management implementation. Findings indicate that agricultural-management practices to improve water quality are most effective if their overall design effects on surface- and ground-water systems are considered in their design.

  17. Implications of climate change scenarios for agriculture in alpine regions--a case study in the Swiss Rhone catchment.

    PubMed

    Fuhrer, J; Smith, P; Gobiet, A

    2014-09-15

    Coping with climate change in agriculture requires knowledge of trends in agro-climatic conditions with a focus at the smaller scales where decisions are taken. As part of the EU FP7 ACQWA project, the situation was analyzed for agriculture in the case of the Swiss Rhone catchment (Valais) where cultivation of permanent crops (orchards and vineyards) and livestock production are the most important agro-economic activities. The aim of this study was to use daily data from four downscaled and bias corrected transient climate change scenarios to analyze changes in water and temperature related indices over the period 1951-2050 for three locations (Aigle, Sion, Montana) that are representative of different production zones in the catchment. The results indicate that most relevant implications are caused by projected changes in temperature and not in precipitation. They indicate an extension of the thermal growing season with potentially positive effects on pasture and livestock production, most pronounced at the mountain site (Montana), but a trend towards increasing risks of frost in permanent crops and in heat stress for livestock at the valley bottom (Aigle, Sion). The increase in water requirement for irrigation in 2021-2050 relative to 1981-2009 is moderate (4-16%, depending on location). However, in years with low amounts of snow and rain, in small catchments with a nival regime, reduced water supply by rivers could restrict the surface area of grassland that can be irrigated, particularly during springtime. It is concluded that coping with heat-related risks may be most needed at the lower cropland and pasture sites while water-related issues would become more relevant in more elevated locations where pasture-based livestock production is the dominant type of agricultural land use.

  18. Relationship Between Watershed Land Use and Denitrification Enzyme Activity in Headwater Streams

    EPA Science Inventory

    Headwater streams are the dominant land-water interface across much of the landscape. Denitrification is an important ecological service provided by headwater streams. Anthropogenic inputs of N to terrestrial ecosystems largely result from agricultural practices. Animal agricultu...

  19. Integration of a modeling task in water policy design - Example of a prospective scenarios approach on an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Moreau, P.; Raimbault, T.; Durand, P.; Gascuel-Odoux, C.; Salmon-Monviola, J.; Masson, V.; Cordier, M. O.

    2010-05-01

    duration and by promoting CC in the autumn period. To conclude, the ability of TNT2 model to simulate catchments hydrology and nitrogen cycle has been demonstrated with a fine spatial resolution and fine degree of details in agricultural practices. A generic participatory 3-step-method for scenario analysis has been developed to ensure an appropriation of the prospective modeling task in decision support. Finally, the most advantageous CC management has been brought out and its effect of N cycling quantified. Keywords: hydrology, nitrogen, distributed model, diffuse pollution, scenario, decision support

  20. Application of strontium isotope measurements to trace sediment sources in an upstream agricultural catchment (Loire River basin, France)

    NASA Astrophysics Data System (ADS)

    Le Gall, Marion; Evrard, Olivier; Thil, François; Foucher, Anthony; Salvador-Blanes, Sébastien; Cerdan, Olivier; Ayrault, Sophie

    2015-04-01

    Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. It accelerates the supply of sediment to the rivers and degrades water quality. To limit those impacts and optimize management programs in such areas, sources of sediment need to be identified and sediment transport to be controlled. Here, we determined the sources of suspended sediment in the Louroux (24 km², French Loire River basin), a small catchment representative of lowland cultivated environments of Northwestern Europe. In this catchment, channels have been reshaped and 220 tile drain outlets have been installed over the last several decades. As a result, soil erosion and sediment fluxes have increased drastically. The variation of 87Sr/86Sr ratios, driven by the weathering of rocks with different ages and chemical composition, may reflect the mixing of different sediment sources. Strontium isotopic ratios (87Sr/86Sr) were therefore determined in potential soil sources, suspended particulate matter (SPM) and a sediment core sampled in the Louroux Pond at the catchment outlet. Soil, SPM and core samples displayed significantly different isotopic signatures. 87Sr/86Sr ratios in soil samples varied from 0.712763 to 0.724631 ± 0.000017 (2σ, n=20). Highest values were observed in silicic parts of the catchment whereas the lower values were identified in a calcareous area close to the Louroux Pond. 87Sr/86Sr ratios in SPM (0.713660 to 0.725749 ± 0.000017, 2σ, n=20) plotted between the soil and sediment core (0.712255 to 0.716415 ± 0.000017, 2σ, n=12), suggesting the presence of particles originating from at least two different lithological sources, i.e. silicic rocks and carbonate material. Variations in 87Sr/86Sr ratios in the outlet core sample were used to reconstruct the sedimentary dynamics in the catchment during the last decades. These results will guide the future implementation of appropriate management practices aiming to reduce erosion in upstream

  1. Effect of large rainfall events on runoff and soil losses in two small experimental agricultural catchments in Southern Spain

    NASA Astrophysics Data System (ADS)

    Gómez, J. A.; Taguas, E. V.; Vanwalleghem, T.; Pérez-Alcántara, R.

    2010-05-01

    This communication presents the results and a preliminary discussion of the results of a medium term monitoring of runoff and soil losses in two small agricultural catchments, Conchuela and Puente Genil, of 8.0 and 6.1 ha respectively. Puente Genil has been monitored since 2005 and Conchuela since 2006. The gauging station at both catchments is composed of a measure flume provided of an ultrasonic water depth sensor, a raingauge and an ISCO sampler for taking suspended sediment samplers. The Puente Genil catchment presents average slope of 15%, and is on a soil of loamy sand texture, while La Conchuela presents an average slope of 9% and is on a clay soil. Soil management in both catchments is based on no tillage with mechanical or chemical control of the adventitious vegetation growing in the inter tree space since mid March, to avoid competition for soil water with the olive trees. The years monitored since 2005/06 to 2008/09 were significantly below the average rainfall in the region with a reduced number of intense events. So, annual soil losses for both basins ranged from 4 to less than 0.2 t ha-1 year-1, and average annual runoff coefficients ranging from 8 to less than 3 %. Hydrological year 2009/2010 has presented unusually high rainfalls. By early January cumulative rainfall from September first is above the average annual rainfall, and a large number of highly erosive events have been monitored in both catchments. Provisional results indicate that these periodical episodes of moist years with high intensity events are key in evaluating the erosive and hydrological behaviour of agricultural areas in Southern Spain. For instance, the sediment delivered from La Conchuela trough the monitoring station during 2009/10 has been estimated in 13.9 t ha-1 by January 2nd. The practical implications for monitoring schemes under these conditions, and the need of long term experiments that need to be complemented with model analysis will be discussed trough this

  2. The 20th century whole-basin trophic history of an inter-drumlin lake in an agricultural catchment.

    PubMed

    Jordan, Philip; Rippey, Brian; Anderson, N John

    2002-10-07

    Eight 1-m sediment cores were extracted from across the basin of Friary Lough, a 5.4-ha eutrophic lake in a wholly grassland agricultural catchment in Co. Tyrone, Northern Ireland. Sedimentary TP, diatom inferred TP, Ca, Na, Fe, Mn, loss-on-ignition (LOI), dry weight and density were determined in the core profiles. Core dating and correlation gave a 210Pb, 137Cs and 241Am chronology from 1906 to 1995 and enabled a whole-basin estimate of chemical and sediment accumulation rate over the 20th Century. The major changes for all parameters occurred after c. 1946. Sediment accumulation rate was most influenced by organic matter accumulations, probably of planktonic origin, and increasing after c. 1946. Inorganic sediment accumulation rate was found to be largely unchanging through the century at 10 t km(-2) yr(-1) when expressed as catchment exports. All chemical accumulation rate changes occurred after c. 1946. Total phosphorus accumulation rate, however, was found to be the only chemical to be increasing throughout the epilimnion and hypolimnion areas of the sedimentary basin at an average of 22.5 mg m(-2) yr(-1) between 1946 and 1995. The other chemical parameters showed increasing accumulation rates after c. 1946 in the epilimnion part of the basin only. Interpreted in terms of whole-basin sedimentation and catchment export processes over time, it is suggested that diffuse TP inputs are independent of sediment inputs. This corresponds to hydrochemical models that suggest soluble P as the primary fraction that is lost from grassland catchments. The increase in sedimentary TP accumulation rate, and DI-TP concentration, are also explained with regard to current models that suggest increases in runoff P concentrations from elevated soil P concentrations. Increases in eplimnion chemical and sediment accumulation rate after c. 1946 may be due to local erosion that has limited impact on lake basin sedimentation.

  3. Relating land use patterns to stream nutrient levels in red soil agricultural catchments in subtropical central China.

    PubMed

    Wang, Yi; Li, Yong; Liu, Xinliang; Liu, Feng; Li, Yuyuan; Song, Lifang; Li, Hang; Ma, Qiumei; Wu, Jinshui

    2014-09-01

    Land use has obvious influence on surface water quality; thus, it is important to understand the effects of land use patterns on surface water quality. This study explored the relationships between land use patterns and stream nutrient levels, including ammonium-N (NH4 (+)-N), nitrate-N (NO3 (-)-N), total N (TN), dissolved P (DP), and total P (TP) concentrations, in one forest and 12 agricultural catchments in subtropical central China. The results indicated that the TN concentrations ranged between 0.90 and 6.50 mg L(-1) and the TP concentrations ranged between 0.08 and 0.53 mg L(-1), showing that moderate nutrient pollution occurred in the catchments. The proportional areal coverages of forests, paddy fields, tea fields, residential areas, and water had distinct effects on stream nutrient levels. Except for the forest, all studied land use types had a potential to increase stream nutrient levels in the catchments. The land use pattern indices at the landscape level were significantly correlated to N nutrients but rarely correlated to P nutrients in stream water, whereas the influence of the land use pattern indices at the class level on stream water quality differentiated among the land use types and nutrient species. Multiple regression analysis suggested that land use pattern indices at the class level, including patch density (PD), largest patch index (LPI), mean shape index (SHMN), and mean Euclidian nearest neighbor distance (ENNMN), played an intrinsic role in influencing stream nutrient quality, and these four indices explained 35.08 % of the variability of stream nutrient levels in the catchments (p<0.001). Therefore, this research provides useful ideas and insights for land use planners and managers interested in controlling stream nutrient pollution in subtropical central China.

  4. Runoff production in a small agricultural catchment in Lao PDR: influence of slope, land-use and observation scale

    NASA Astrophysics Data System (ADS)

    Patin, J.; Ribolzi, O.; Mugler, C.; Valentin, C.; Mouche, E.

    2010-12-01

    After years of traditional slash and burn cultures, the Houay Pano catchment is now under high land pressures due to population resettling and environmental preservation policies. This evolution leads to rapid land-use changes in the uplands, such as fallow time reductions and growing of cash crops as teaks or banana. The catchment is located in the Luang Prabang province, in the north of Lao PDR and was selected in late 1998 as a benchmark site for the Managing Soil Erosion Consortium (MSEC). It is a small (60ha) agricultural catchment representative of the rural mountainous South East Asia : it exhibits steep cultivated slopes (from 2% to more than 110%) under a wet-dry monsoon climate. To understand the partition between runoff and infiltration, data from runoff on 20 plot experiments (1m2) under natural rainfall and with representative slopes and land uses is collected from 2003 to 2009. A simulated rainfall experiment was conducted in 2002 on bare soil plots (1m2) with different antecedent cultures. We investigate the role of crust, slope and land-use on runoff production at different scales. A model accounting for small scale variability is applied to compute the time and space variations of soil infiltrability at the plot scale (1m2) and sub-catchment scale (0.6ha). From the hypothesis of exponentially distributed infiltrabilities at the centimeter scale, we found that infiltration is log-normaly distributed over time for a given land use. The median infiltrability vary from 10mm/h under teak cultures to 150mm/h on plots with fallow. Variations along a year are tribute to many meteorological and human factors.

  5. Water quality impact assessment of agricultural Beneficial Management Practices (BMPs) simulated for a regional catchment in Quebec, Eastern Canada

    NASA Astrophysics Data System (ADS)

    Rousseau, Alain N.; Hallema, Dennis W.; Gumiere, Silvio J.; Savary, Stéphane; Hould Gosselin, Gabriel

    2014-05-01

    Water quality has become a matter of increasing concern over the past four decades as a result of the intensification of agriculture, and more particularly so in Canada where agriculture has evolved into the largest non-point source of surface water pollution. The Canadian WEBs project (Watershed Evaluation of Beneficial Management Practices, BMPs) was initiated in order to determine the efficiency of BMPs in improving the surface water quality of rural catchments, and the economic aspects related to their implementation on the same scale. In this contribution we use the integrated watershed modelling platform GIBSI (Gestion Intégrée des Bassins versants à l'aide d'un Système Informatisé) to evaluate the effects of various BMPs on sediment and nutrient yields and, in close relation to this, the surface water quality for the Beaurivage River catchment (718 km2) in Quebec, eastern Canada. A base scenario of the catchment is developed by calibrating the different models of the GIBSI platform, namely HYDROTEL for hydrology, the Revised Universal Soil Loss Equation (RUSLE) for soil erosion, the Erosion-Productivity Impact Calculator (EPIC) of the Soil and Water Assessment Tool (SWAT) for contaminant transport and fate, and QUAL2E for stream water quality. Four BMPs were analysed: (1) vegetated riparian buffer strips, (2) precision slurry application, (3) transition of all cereal and corn fields to grassland (grassland conversion), and (4) no-tillage on corn fields. Simulations suggest that riparian buffer strips and grassland conversion are more effective in terms of phosphorus, nitrogen and sediment load reduction than precision slurry application and no-tillage on corn fields. The results furthermore indicate the need for a more profound understanding of sediment dynamics in streams and on riparian buffer strips.

  6. Runoff and sediment loss responses to rainfall and land use in two agricultural catchments on the Loess Plateau of China

    NASA Astrophysics Data System (ADS)

    Kang, Shaozhong; Zhang, Lu; Song, Xiaoyu; Zhang, Shuhan; Liu, Xianzhao; Liang, Yinli; Zheng, Shiqing

    2001-04-01

    Soil erosion is a severe problem hindering sustainable agriculture on the Loess Plateau of China. Plot experiments were conducted under the natural rainfall condition during 1995-1997 at Wangdongguo and Aobao catchments in this region to evaluate the effects of various land use, cropping systems, land slopes and rainfall on runoff and sediment losses, as well as the differences in catchment responses. The experiments included various surface conditions ranging from bare soil to vegetated surfaces (maize, wheat residue, Robinia pseudoacacia L., Amorpha fruticosa L., Stipa capillata L., buckwheat and Astragarus adsurgens L.). The measurements were carried out on hill slopes with different gradients (i.e. 0 ° to 36 °). These plots varied from 20 to 60 m in length. Results indicated that runoff and erosion in this region occurred mainly during summer storms. Summer runoff and sediment losses under cropping and other vegetation were significantly less than those from ploughed bare soil (i.e. without crop/plant or crop residue). There were fewer runoff and sediment losses with increasing canopy cover. Land slope had a major effect on runoff and sediment losses and this effect was markedly larger in the tillage plots than that in the natural grass and forest plots, although this effect was very small when the maximum rainfall intensity was larger than 58·8 mm/h or smaller than 2·4 mm/h. Sediment losses per unit area rose with increasing slope length for the same land slope and same land use. The effect of slope length on sediment losses was stronger on a bare soil plot than on a crop/plant plot. The runoff volume and sediment losses were both closely related to rainfall volume and maximum intensity, while runoff coefficient was mainly controlled by maximum rainfall intensity. Hortonian overland flow is the dominant runoff process in the region. The differences in runoff volume, runoff coefficient and sediment losses between the catchments are mainly controlled by the

  7. Impact of conservation agriculture on catchment runoff and soil loss under changing climate conditions in May Zeg-zeg (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Lanckriet, Sil; Araya, Tesfay; Cornelis, Wim; Verfaillie, Els; Poesen, Jean; Govaerts, Bram; Bauer, Hans; Deckers, Jozef; Haile, Mitiku; Nyssen, Jan

    2012-12-01

    SummaryThis study evaluates the practice of conservation agriculture (CA) in the May Zeg-zeg catchment (MZZ; 187 ha) in the North Ethiopian Highlands as a soil management technique for reducing soil loss and runoff, and assesses the consequences of future large-scale implementation on soil and hydrology at catchment-level. The study of such practice is important especially under conditions of climate change, since EdGCM (Educational Global Climate Model) simulation predicts by 2040 an increase in precipitation by more than 100 mm yr-1 in the study area. Firstly, field-saturated infiltration rates, together with soil texture and soil organic carbon contents, were measured. The relation with local topography allows to generate a pedotransfer function for field-saturated infiltration rate, and spatial interpolation with Linear Regression Mapping was used to map field-saturated infiltration rates optimally within the catchment. Secondly, on several farmlands, CA was checked against plain tillage (PT) for values of field-saturated infiltration rates, soil organic carbon, runoff and soil loss. Results show no significant differences for infiltration rates but significant differences for runoff and soil loss (as measured in the period 2005-2011). Runoff coefficients were 30.4% for PT and 18.8% for CA; soil losses were 35.4 t ha-1 yr-1 for PT and 14.4 t ha-1 yr-1 for CA. Thirdly, all collected information was used to predict future catchment hydrological response for full-implementation of CA under the predicted wetter climate (simulation with EdGCM). Curve Numbers for farmlands with CA were calculated. An area-weighted Curve Number allows the simulation of the 2011 rainy season runoff, predicting a total runoff depth of 23.5 mm under CA and 27.9 mm under PT. Furthermore, the Revised Universal Soil Loss Equation management factor P was calibrated for CA. Results also show the important influence of increased surface roughness on water ponding, modeled with a hydrologic

  8. An integrated model for simulating nitrogen trading in an agricultural catchment with complex hydrogeology.

    PubMed

    Cox, T J; Rutherford, J C; Kerr, S C; Smeaton, D C; Palliser, C C

    2013-09-30

    Nitrogen loads to several New Zealand lakes are dominated by nonpoint runoff from pastoral farmland which adversely affects lake water quality. A 'cap and trade' scheme is being considered to help meet targets set for nitrogen loads to Lake Rotorua, and a numerical model, NTRADER, has been developed to simulate and compare alternative schemes. NTRADER models both the geophysics of nitrogen generation and transport, including groundwater lag times, and the economics of 'cap and trade' schemes. It integrates the output from several existing models, including a farm-scale nitrogen leaching and abatement model, a farm-scale management economic model, and a catchment-scale nitrogen transport model. This paper details modeling methods and compares possible trading program design features for the Lake Rotorua catchment. Model simulations demonstrate how a cap and trade program could be used to effectively achieve challenging environmental goals in the targeted catchment. However, results also show that, due to complex hydrogeology, satisfactory environmental outcomes may be not achieved unless groundwater lag times are incorporated into the regulatory scheme. One way to do this, as demonstrated here, would be to explicitly include lag times in the cap and trade program. The utility of the model is further demonstrated by quantifying relative differences in abatement costs across potential regulatory schemes.

  9. Climate Change Impact on the Hydrology and Water Quality of a Small Partially-Irrigated Agricultural Lowland Catchment

    NASA Astrophysics Data System (ADS)

    Visser, A.; Kroes, J.; van Vliet, M. T.; Blenkinsop, S.; Broers, H.

    2010-12-01

    The objective of this study was to assess the potential effects of climate change on the hydrology of the small partially-irrigated agricultural lowland catchment of the Keersop, in south of the Netherlands, as well as the transport of a pre-existing spatially extensive trace metal contamination. The area surrounding the Keersop has been contaminated with heavy metals by the atmospheric emissions of four zinc ore smelters. This heavy metal contamination, with Cd and Zn for example, has accumulated in the topsoil and leaches towards the surface water system, especially during periods with high groundwater levels and high discharge rates. Daily time-series of precipitation and potential evapotranspiration were derived from the results of eight regional climate model experiments under the SRES A2 emissions scenario. They each span 100 years and are representative for the periods 1961-1990 (“baseline climate”) and 2071-2100 (“future climate”). The time-series of future climate were characterized by lower precipitation (-1% to -12%) and higher air temperatures (between 2°C and 5°C), and as a result higher potential evapotranspiration, especially in summer. The time-series were used to drive the quasi-2D unsaturated-saturated zone model (SWAP) of the Keersop catchment (43 km2). The model consisted of an ensemble of 686 1D models, each of which represented a 250x250 m area within the catchment. Simulation results for the future climate scenarios show a shift in the water balance of the catchment. The decrease in annual rainfall is nearly compensated by an increase in irrigation in the catchment, if present day irrigation rules are followed. On the other hand, both evaporation and transpiration fluxes increase. This increase is compensated by a decrease in the drainage flux and groundwater recharge. As a result, groundwater levels decline and the annual discharge of the Keersop stream decreases under all future climate scenarios, by 26% to 46%. Because Cd and Zn

  10. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; hydrology of a small carbonate site near Ephrata, Pennsylvania, prior to implementation of nutrient management

    USGS Publications Warehouse

    Koerkle, E.H.; Hall, D.W.; Risser, D.W.; Lietman, P.L.; Chichester, D.C.

    1997-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture and Pennsylvania Department of Environmental Protection, investigated the effects of agricultural best-management practices on water quality in the Conestoga River headwaters watershed. This report describes environmental factors and the surface-water and ground-water quality of one 47.5-acre field site, Field-Site 2, from October 1984 through September 1986, prior to implementation of nutrient management. The site is partially terraced agricultural cropland underlain by carbonate rock. Twenty-seven acres are terraced, pipe-drained, and are under no-till cultivation. The remaining acreage is under minimum-till cultivation. Corn is the primary crop. The average annual rate of fertilization at the site was 480 pounds per acre of nitrogen and 110 pounds per acre of phosphorus. An unconfined limestone and dolomitic aquifer underlies the site, Depth to bedrock ranges from 5 to 30 feet below land surface. Estimated specific yields range from 0.05 to 0.10, specific capacities of wells range from less than 1 to about 20 gallons per minute per foot of drawdown, and estimates of transmissivities range from 10 to 10,000 square feet per day. Average ground-water recharge was estimated to be about 23 inches per year. The specific capacity and transmissivity data indicate that two aquifer regimes are present at the site. Wells drilled into dolomites in the eastern part of the site have larger specific capacities (averaging 20 gallons per minute per foot of drawdown) relative to specific capacities (averaging less than 1 gallon per minute per foot of drawdown) of wells drilled into limestones in the western part of the site. Median concentrations of soil-soluble nitrate and soluble phosphorus in the top 4 feet of silt- or silty-clay-loam soil ranged from 177 to 329 and 8.5 to 35 pounds per acre, respectively. Measured runoff from the pipe-drained terraces ranged from 10 to 48,000 cubic feet and was

  11. Opportunities provided by UAVs to monitor erosion processes in agricultural catchments: a case study from Northern France

    NASA Astrophysics Data System (ADS)

    Frankl, Amaury; Stal, Cornelis; De Wit, Bart; De Wulf, Alain; Salvador, Pierre-Gil; Nyssen, Jan

    2014-05-01

    In erosion studies, accurate spatio-temporal data are required to fully understand the processes involved and their relationship with environmental controls. With cameras being mounted on Unmanned Aerial Vehicles (UAVs), the latter allow to collect low-altitude aerial photographs over small catchments in a cost-effective and rapid way. From large data sets of overlapping aerial photographs, Structure from Motion - Multi View Stereo workflows, integrated in various software such as PhotoScan used here, allow to produced detailed Digital Surface Models (DSMs) and ortho-mosaics. In this study we present the results from a survey carried out in a small agricultural catchment near Hallines, in Northern France. A DSM and ortho-mosaic was produced of the catchment using photographs taken from a low-cost radio-controlled microdrone (DroneFlyer Hexacopter). Photographs were taken with a Sony Nex 5 (16.1 M pixels) camera having a fixed normal lens of 50 mm. In the field, Ground Control Points were materialized by unambiguously determinable targets, measured with a 1'' total station (Leica TS15i). Cross-sections of rills and ephemeral gullies were also quantified from total station measurements and from terrestrial image-based 3D modelling. These data allowed to define the accuracy of the DSM and the representation of the erosion features in it. The feasibility of UAVs photographic surveys to improve our understanding on water-erosion processes such as sheet, rill and gully erosion is discussed. Keywords: Ephemeral gully, Erosion study, Image-based 3D modelling, Microdrone, Rill, UAVs.

  12. Defining optimal DEM resolutions and point densities for modelling hydrologically sensitive areas in agricultural catchments dominated by microtopography

    NASA Astrophysics Data System (ADS)

    Thomas, I. A.; Jordan, P.; Shine, O.; Fenton, O.; Mellander, P.-E.; Dunlop, P.; Murphy, P. N. C.

    2017-02-01

    Defining critical source areas (CSAs) of diffuse pollution in agricultural catchments depends upon the accurate delineation of hydrologically sensitive areas (HSAs) at highest risk of generating surface runoff pathways. In topographically complex landscapes, this delineation is constrained by digital elevation model (DEM) resolution and the influence of microtopographic features. To address this, optimal DEM resolutions and point densities for spatially modelling HSAs were investigated, for onward use in delineating CSAs. The surface runoff framework was modelled using the Topographic Wetness Index (TWI) and maps were derived from 0.25 m LiDAR DEMs (40 bare-earth points m-2), resampled 1 m and 2 m LiDAR DEMs, and a radar generated 5 m DEM. Furthermore, the resampled 1 m and 2 m LiDAR DEMs were regenerated with reduced bare-earth point densities (5, 2, 1, 0.5, 0.25 and 0.125 points m-2) to analyse effects on elevation accuracy and important microtopographic features. Results were compared to surface runoff field observations in two 10 km2 agricultural catchments for evaluation. Analysis showed that the accuracy of modelled HSAs using different thresholds (5%, 10% and 15% of the catchment area with the highest TWI values) was much higher using LiDAR data compared to the 5 m DEM (70-100% and 10-84%, respectively). This was attributed to the DEM capturing microtopographic features such as hedgerow banks, roads, tramlines and open agricultural drains, which acted as topographic barriers or channels that diverted runoff away from the hillslope scale flow direction. Furthermore, the identification of 'breakthrough' and 'delivery' points along runoff pathways where runoff and mobilised pollutants could be potentially transported between fields or delivered to the drainage channel network was much higher using LiDAR data compared to the 5 m DEM (75-100% and 0-100%, respectively). Optimal DEM resolutions of 1-2 m were identified for modelling HSAs, which balanced the need

  13. Predicting alpine headwater stream intermittency: a case study in the northern Rocky Mountains

    USGS Publications Warehouse

    Sando, Thomas R.; Blasch, Kyle W.

    2015-01-01

    This investigation used climatic, geological, and environmental data coupled with observational stream intermittency data to predict alpine headwater stream intermittency. Prediction was made using a random forest classification model. Results showed that the most important variables in the prediction model were snowpack persistence, represented by average snow extent from March through July, mean annual mean monthly minimum temperature, and surface geology types. For stream catchments with intermittent headwater streams, snowpack, on average, persisted until early June, whereas for stream catchments with perennial headwater streams, snowpack, on average, persisted until early July. Additionally, on average, stream catchments with intermittent headwater streams were about 0.7 °C warmer than stream catchments with perennial headwater streams. Finally, headwater stream catchments primarily underlain by coarse, permeable sediment are significantly more likely to have intermittent headwater streams than those primarily underlain by impermeable bedrock. Comparison of the predicted streamflow classification with observed stream status indicated a four percent classification error for first-order streams and a 21 percent classification error for all stream orders in the study area.

  14. Applicability of rapid and on-site measured enzyme activity for surface water quality monitoring in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Stadler, Philipp; Farnleitner, Andreas H.; Sommer, Regina; Kumpan, Monika; Zessner, Matthias

    2014-05-01

    For the near real time and on-site detection of microbiological fecal pollution of water, the measurement of beta-D- Glucuronidase (GLUC) enzymatic activity has been suggested as a surrogate parameter and has been already successfully operated for water quality monitoring of ground water resources (Ryzinska-Paier et al. 2014). Due to possible short measure intervals of three hours, this method has high potential as a water quality monitoring tool. While cultivation based standard determination takes more than one working day (Cabral 2010) the potential advantage of detecting the GLUC activity is the high temporal measuring resolution. Yet, there is still a big gap of knowledge on the fecal indication capacity of GLUC (specificity, sensitivity, persistence, etc.) in relation to potential pollution sources and catchment conditions (Cabral 2010, Ryzinska-Paier et al. 2014). Furthermore surface waters are a big challenge for automated detection devices in a technical point of view due to the high sediment load during event conditions. This presentation shows results gained form two years of monitoring in an experimental catchment (HOAL) dominated by agricultural land use. Two enzymatic measurement devices are operated parallel at the catchment outlet to test the reproducibility and precision of the method. Data from continuous GLUC monitoring under both base flow and event conditions is compared with reference samples analyzed by standardized laboratory methods for fecal pollution detection (e.g. ISO 16649-1, Colilert18). It is shown that rapid enzymatic on-site GLUC determination can successfully be operated from a technical point of view for surface water quality monitoring under the observed catchment conditions. The comparison of enzyme activity with microbiological standard analytics reveals distinct differences in the dynamic of the signals during event conditions. Cabral J. P. S. (2010) "Water Microbiology. Bacterial Pathogens and Water" International Journal of

  15. Water storage equity and safety assurance policy to mitigate potential 'dual-extreme cumulative threats' in agricultural catchments

    NASA Astrophysics Data System (ADS)

    Pisaniello, John D.; Tingey-Holyoak, Joanne L.

    2017-02-01

    Farm dams that are not managed properly at the individual level can create water storage equity and safety threats to downstream communities and the environment that aggregate at the catchment level: a potential 'dual-extreme cumulative' problem. The paper provides indicative evidence and develops understanding of this novel phenomenon and associated policy needs within the Australian setting comprising dual hydrologic extremes of floods and droughts, further exacerbated by climate change. This is achieved through comparative case studies involving surveys of both dam owner perceptions and dam management practices in four States representing a complete range of integrated policy approaches from weak to strong. Survey results find most farmers do not believe dam maintenance is important, will undertake spillway blocking and do not plan for emergencies. These results are supported by physical on-site findings of farmers neglecting dams and blocking or under-designing spillways, in turn storing more water than they are entitled and creating unsafe dams at both the individual and cumulative levels. From detailed cross-case comparative assessment against policy context, it emerges that on-farm perceptions and practices form a range of 'acceptability' of dam management that directly reflects policy strength and integration in each setting. The paper advances the international small dams policy, agricultural water management and hydrology literatures, evidencing the need for effective integrated policy to mitigate dual extreme cumulative threats. Importantly, guidance is provided to jurisdictions internationally with high inter-annual rainfall variation on how best to design integrated policy that can achieve both water storage equity and safety in agricultural catchments.

  16. Interannual climate variability and spatially heterogeneous improvement of agricultural management impede detection of a decreasing trend in nitrate pollution in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Fovet, Ophélie; Dupas, Rémi; Durand, Patrick; Gascuel-Odoux, Chantal; Gruau, Gérard; Hamon, Yannick; Petitjean, Patrice

    2016-04-01

    Despite widespread implementation of the nitrate directive in the European Union since the 1990s, the impact on nitrate concentration in rivers is limited (Bouraoui and Grizzetti, 2011). To assess whether this lack of response is due to the long time lags of nitrate transfer or to inadequate programs of measure, long term river and groundwater monitoring data are necessary. This study analyses 15 years of daily nitrate concentration data at the outlet of an intensively farmed catchment in Western France (Kervidy-Naizin, 5 km²) and quarterly nitrate concentration data in the groundwater of two hillslopes equipped with piezometers (Kerroland and Gueriniec) within the same catchment. In this catchment groundwater contribution to annual stream flow is dominant. The objectives of this study were to i) disentangle the influence of interannual climate variability and improvement of agricultural practices (i.e. reduction in N surplus) in the stream chemistry and ii) discuss the reasons for slow catchment recovery from nitrate pollution by comparing trends in groundwater and stream concentrations. Analysis of stream data showed that flow-weighted mean annual concentration at the outlet of the Kervidy-Naizin catchment has decreased by 1.2 mg NO3- l-1 yr-1 from 1999 to 2015. This decrease was slow but significant (p value < 0.01) even though interannual climate variability (i.e. annual cumulated runoff) added noise to the signal: i) deviation in the linear model of nitrate decrease with time was negatively correlated with annual runoff (r = -0.54, p < 0.01) and ii) local minimums in the nitrate time series were coincident with local maximums in the annual runoff. Thus high runoff during wet years led to dilution of the nitrate originating from groundwater, which added variability to the signal of linear decrease in stream concentration. Analysis of groundwater data showed a significant and sharp decrease in nitrate concentration in the Kerroland piezometer transect (4.0 mg

  17. Concentration patterns of agricultural pesticides and urban biocides in surface waters of a catchment of mixed land use

    NASA Astrophysics Data System (ADS)

    Stamm, C.; Wittmer, I.; Bader, H.-P.; Scheidegger, R.; Alder, A.; Lück, A.; Hanke, I.; Singer, H.

    2009-04-01

    Organic pesticides and biocides that are found in surface waters, can originate from agricultural and urban sources. For a long time, agricultural pesticides have received substantially more attention than biocidal compounds from urban use like material protection or in-can preservatives (cosmetics etc.). Recent studies however revealed that the amounts of urban biocides used may exceed those of agricultural pesticides. This study aims at comparing the input of several important pesticides and biocides into a small Swiss stream with a special focus on loss events triggered by rainfall. A set of 16 substances was selected to represent urban and agricultural sources. The selected substances are either only used as biocides (irgarol, isothiazolinones, IPBC), as pesticides (atrazine, sulcotrione, dichlofluanid, tolylfluanid) or have a mixed use (isoproturon, terbutryn, terbutylazine, mecoprop, diazinon, carbendazim) The study catchment has an area of 25 km2 and is inhabited by about 12'000 people. Four sampling sites were selected in the river system in order to reflect different urban and agricultural sources. Additionally, we sampled a combined sewer overflow, a rain sewer and the outflow of a wastewater treatment plant. At each site discharge was measured continuously from March to November 2007. During 16 rain events samples were taken by automatic devices at a high temporal resolution. The results, based on more than 500 analyzed samples, revealed distinct concentration patterns for different compounds and sources. Agricultural pesticides exhibited a strong seasonality as expected based on the application periods. During the first one or two rain events after application the concentrations reached up to several thousand ng/l during peak flow (atrazine, isoproturon). The temporal patterns of urban biocides were more diverse. Some compounds obviously stem from permanent sources independent of rainfall because they were found mostly in the outlet of the wastewater

  18. Management of sediment and erosion processes in boreal headwaters affected by peatland drainage

    NASA Astrophysics Data System (ADS)

    Marttila, H.; Tammela, S.; Kløve, B.

    2009-04-01

    Peatland drainage for forestry, agriculture, peat harvesting and urban infrastructure has been altered landscape in Finland. Pristine peatlands and headwaters provide important hydrological and ecological functions that can be lost after drainage. The drainage has resulted in increase of forest resources but also negative environmental effects including changes in runoffs, erosion processes, siltation and eutrophication. The changes that can occur after drainage are, however, complex and must be better understood if the negative impacts of drainage are to be reduced or prevented. Especially erosion and transport processes of organic peat sediment are not well understood (Marttila and Kløve, 2008). Methods for controlling the sediment load include erosion and transport control practices in the catchment area (Marttila and Kløve, 2009; Tammela et al. 2009). The presentation/poster will present methods and preliminary results project from Northern Finland. The issues especially covered are sediment erosion and transport and methods to restore and reduce impacts of peatland drainage in boreal headwaters. Keywords: sediment transport, erosion, peatland drainage, organic and inorganic sediment, stream and catchment restoration, management, environment References: Marttila, H. and Kløve. B. 2008. Erosion and delivery of deposited peat sediment. Water Resources Research. 44 (6). Marttila, H. Kløve. B. 2009. Retention of sediment and nutrient loads with peak runoff control. Journal of Irrigation and Drainage Engineering (in press). Tammela, S. Marttila, H. and Kløve. B. 2009. Effect and design of an underminer structure on flow distribution and local bed topography (submitted).

  19. Optimization based trade-off analysis of biodiesel crop production for managing a German agricultural catchment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In agricultural production, the existence of multiple trade-offs among several conflicting objectives, such as food production, water quantity, water quality, biodiversity and ecosystem services, is well known. However, quantification of the trade-offs among objectives in bioenergy crop production i...

  20. Evaluation of detailed water quality and quantity monitoring system in a small agricultural catchment - discrete vs. continuous approach

    NASA Astrophysics Data System (ADS)

    Fučík, Petr; Kaplická, Markéta; Kvítek, Tomáå.¡

    2010-05-01

    To achieve the obligatory limits set up by the WFD (Water Frame Directive) in water bodies, there is an urgent need of attainments conc. water quality and quantity dynamics which can be gained only by a detailed monitoring. Continuous monitoring system of surface, subsurface and ground waters is one of the essential tools, enabling to thoroughly understand the processes of water quality dynamics in a catchment as well as to trace the sources and pathways of pollutants during various rainfall - runoff events. In this paper, there are described results of concentrations and loads of N-NO3, N-NH4 and Ptot, realized by assessment and comparison of two different approaches - regular and intensive monitoring concepts. The analysis was carried out in five measuring points - in the catchment closing profile and in four subcatchments (three of them tile drained) of a small agricultural catchment during the year 2009. Monitored catchment is located on the Kopaninský stream, which is situated in the south - eastern part of the Švihov drinking water reservoir basin on the Želivka river, in the Bohemo-Moravian Highland in the Czech Republic. The experimental catchment occupies 7.1 km2, dominating land use type is ploughland (50%), followed by forests (37%) and grasslands (12%). The catchment contains several measuring sites - profiles, equipped with V - notch type weirs and ultrasound probes connected to dataloggers for water level recording. The regular (discrete) monitoring lied in a fortnightly accomplished manual withdrawal of a 0.5 l sample from the upper third share of actual water column in the case of surface water courses, or directly from the tile drainage outlet, and measuring the actual water level (discharge). Average monthly load L (kg*month-1) was then calculated according to the following relationship: L = [ci*Qi+ci+1*Qi+1* 0.0864] n, where ci is concentration of a substance at the time of sampling (mg*l-1), Qiis discharge (l*s-1) at the sampling time, n is

  1. Effectiveness of Conservation Measures in Reducing Runoff and Soil Loss Under Different Magnitude-Frequency Storms at Plot and Catchment Scales in the Semi-arid Agricultural Landscape.

    PubMed

    Zhu, T X

    2016-03-01

    In this study, multi-year stormflow data collected at both catchment and plot scales on an event basis were used to evaluate the efficiency of conservation. At the catchment scale, soil loss from YDG, an agricultural catchment with no conservation measures, was compared with that from CZG, an agricultural catchment with an implementation of a range of conservation measures. With an increase of storm recurrence intervals in the order of <1, 1-2, 2-5, 5-10, 10-20, and >20 years, the mean event sediment yield was 639, 1721, 5779, 15191, 19627, and 47924 t/km(2) in YDG, and was 244, 767, 3077, 4679, 8388, and 15868 t/km(2) in CZG, which represented a reduction effectiveness of 61.8, 55.4, 46.7, 69.2, 57.2, and 66.8 %, respectively. Storm events with recurrence intervals greater than 2 years contributed about two-thirds of the total runoff and sediment in both YDG and CZG catchments. At the plot scale, soil loss from one cultivated slopeland was compared with that from five conservation plots. The mean event soil loss was 1622 t/km(2) on the cultivated slopeland, in comparison to 27.7 t/km(2) on the woodland plot, 213 t/km(2) on the grassland plot, 467 t/km(2) on the alfalfa plot, 236 t/km(2) on the terraceland plot, and 642 t/km(2) on the earthbank plot. Soil loss per unit area from all the plots was significantly less than that from the catchments for storms of all categories of recurrence intervals.

  2. Effectiveness of Conservation Measures in Reducing Runoff and Soil Loss Under Different Magnitude-Frequency Storms at Plot and Catchment Scales in the Semi-arid Agricultural Landscape

    NASA Astrophysics Data System (ADS)

    Zhu, T. X.

    2016-03-01

    In this study, multi-year stormflow data collected at both catchment and plot scales on an event basis were used to evaluate the efficiency of conservation. At the catchment scale, soil loss from YDG, an agricultural catchment with no conservation measures, was compared with that from CZG, an agricultural catchment with an implementation of a range of conservation measures. With an increase of storm recurrence intervals in the order of <1, 1-2, 2-5, 5-10, 10-20, and >20 years, the mean event sediment yield was 639, 1721, 5779, 15191, 19627, and 47924 t/km2 in YDG, and was 244, 767, 3077, 4679, 8388, and 15868 t/km2 in CZG, which represented a reduction effectiveness of 61.8, 55.4, 46.7, 69.2, 57.2, and 66.8 %, respectively. Storm events with recurrence intervals greater than 2 years contributed about two-thirds of the total runoff and sediment in both YDG and CZG catchments. At the plot scale, soil loss from one cultivated slopeland was compared with that from five conservation plots. The mean event soil loss was 1622 t/km2 on the cultivated slopeland, in comparison to 27.7 t/km2 on the woodland plot, 213 t/km2 on the grassland plot, 467 t/km2 on the alfalfa plot, 236 t/km2 on the terraceland plot, and 642 t/km2 on the earthbank plot. Soil loss per unit area from all the plots was significantly less than that from the catchments for storms of all categories of recurrence intervals.

  3. Integrated validation of modeled plant growth, nitrogen- and water-fluxes in the agricultural used Rur catchment in Western Germany

    NASA Astrophysics Data System (ADS)

    Korres, Wolfgang; Klar, Christian; Reichenau, Tim; Fiener, Peter; Schneider, Karl

    2010-05-01

    Numerous studies have shown that agricultural management is one of the key drivers for spatio-temporal patterns of soil moisture in agricultural landscapes. The process-based ecohydrological model components of the integrated decision support system DANUBIA are used to identify the important processes and feedbacks determining soil-moisture patterns in agroecosystems. Interactions between plant growth, soil hydrology and soil nitrogen transformation processes are modeled by using a dynamically coupled modeling approach. Integrative validation of all three model components serves as a basis for modeling analysis of spatial soil moisture patterns. DANUBIA is parameterized and validated for the Rur catchment located in Western Germany. For integrative validation, an extensive three year dataset (2007 - 2009) of soil moisture- (TDR, FDR), plant- (LAI, organ specific biomass and N) and soil- (texture, N, C) measurements was acquired. Plant measurements on an arable land test site were carried out biweekly. Measurements were conducted for winter wheat, maize and sugar beet during the growing season. Soil nitrogen and carbon measurements were taken before, during and after the growing season. Field averages of plant and soil parameters are derived from three individual measuring locations within each test field. Soil moisture was measured with three FDR soil moisture stations in 10 and 30 cm depth. In a grassland test site biomass measurements were carried out biweekly in 2009. Soil moisture was monitored at different locations in up to 60 cm soil depth using FDR- and TDR-stations. Meteorological data was measured with an eddy flux (arable land) and energy flux station (grassland test site). First results of point validation are in very good agreement with field measurements. Model results for winter wheat in 2007/2008 match field measurements well for both, the overall biomass (R2= 0.97, rel. RMSE = 16.8%, Nash Sutcliff - model efficiency ME = 0.96) as well as for

  4. Modeling concentration patterns of agricultural and urban micropollutants in surface waters in catchment of mixed land use

    NASA Astrophysics Data System (ADS)

    Stamm, C.; Scheidegger, R.; Bader, H. P.

    2012-04-01

    Organic micropollutants detected in surface waters can originate from agricultural and urban sources. Depending on the use of the compounds, the temporal loss patterns vary substantially. Therefore models that simulate water quality in watersheds of mixed land use have to account for all relevant sources. We present here simulation results of a transport model that describes the dynamic of several biocidal compounds as well as the behaviour of human pharmaceuticals. The model consists of the sub-model Rexpo simulating the transfer of the compounds from the point of application to the stream in semi-lumped manner. The river sub-model, which is programmed in the Aquasim software, describes the fate of the compounds in the stream. Both sub-models are process-based. The Rexpo sub-model was calibrated at the scale of a small catchment of 25 km2, which is inhabited by about 12'000 people. Based on the resulting model parameters the loss dynamics of two herbicides (atrazine, isoproturon) and a compound of mixed urban and agricultural use (diuron) were predicted for two nested catchment of 212 and 1696 km2, respectively. The model output was compared to observed time-series of concentrations and loads obtained for the entire year 2009. Additionally, the fate of two pharmaceuticals with constant input (carbamazepine, diclofenac) was simulated for improving the understanding of possible degradation processes. The simulated loads and concentrations of the biocidal compounds differed by a factor of 2 to 3 from the observations. In general, the seasonal patterns were well captured by the model. However, a detailed analysis of the seasonality revealed substantial input uncertainty for the application of the compounds. The model results also demonstrated that for the dynamics of rain-driven losses of biocidal compounds the semi-lumped approach of the Rexpo sub-model was sufficient. Only for simulating the photolytic degradation of diclofenac in the stream the detailed

  5. Using 137Cs to study spatial patterns of soil erosion and soil organic carbon (SOC) in an agricultural catchment of the typical black soil region, Northeast China.

    PubMed

    Fang, Haiyan; Li, Qiuyan; Sun, Liying; Cai, Qiangguo

    2012-10-01

    Understanding the spatial pattern of soil organic carbon (SOC) is of great importance because of global environmental concerns. Soil erosion and its subsequent redistribution contribute significantly to the redistribution of SOC in agricultural ecosystems. This study investigated the relationships between (137)Cs and SOC over an agricultural landscape, and SOC redistribution was conducted for an agricultural catchment of the black soil region in Northeast China. The spatial patterns of (137)Cs and SOC were greatly affected by the established shelterbelts and the developed ephemeral gullies. (137)Cs were significantly correlated with SOC when (137)Cs were >2000 Bq m(-2), while no relation was observed between them when (137)Cs were <2000 Bq m(-2). Factors other than soil erosion such as vegetative productivity, mineralization of SOC, landscape position and management induced their spatial difference of (137)Cs and SOC. Using (137)Cs technique to directly study SOC dynamics must be cautious in the black soils. The net SOC loss rate across the entire catchment during 1954-2010 was 92.8 kg ha(-1) yr(-1), with around 42% of the eroded SOC being redeposited within the catchment. Such information can help guide shelterbelt establishment or other land management to reduce SOC loss in the agricultural ecosystems.

  6. Measuring fallout radionuclides to constrain the origin and the dynamics of suspended sediment in an agricultural drained catchment (Loire River basin, France)

    NASA Astrophysics Data System (ADS)

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

    2015-04-01

    Soil erosion reaches problematic levels in agricultural areas of Northwestern Europe where tile drains may accelerate sediment transfer to rivers. This supply of large quantities of fine sediment to the river network leads to the degradation of water quality by increasing water turbidity, filling reservoirs and transporting contaminants. Agricultural patterns and landscapes features have been largely modified by human activities during the last century. To investigate erosion and sediment transport in lowland drained areas, a small catchment, the Louroux (24 km²), located in the French Loire River basin was selected. In this catchment, channels have been reshaped and more than 220 tile drains outlets have been installed after World War II. As a result, soil erosion and sediment fluxes strongly increased. Sediment supply needs to be better understood by quantifying the contribution of sources and the residence times of particles within the catchment. To this end, a network of river monitoring stations was installed, and fallout radionuclides (Cs-137, excess Pb-210 and Be-7) were measured in rainwater (n=3), drain tile outlets (n=4), suspended sediment (n=15), soil surface (n=30) and channel bank samples (n=15) between January 2013 and February 2014. Cs-137 concentrations were used to quantify the contribution of surface vs. subsurface sources of sediment. Results show a clear dominance of particles originating from surface sources (99 ± 1%). Be-7 and excess Pb-210 concentrations and calculation of Be-7/excess Pb-210 ratios in rainfall and suspended sediment samples were used to estimate percentages of recently eroded sediment in rivers. The first erosive winter storm mainly exported sediment depleted in Be-7 that likely deposited on the riverbed during the previous months. Then, during the subsequent floods, sediment was directly eroded and exported to the catchment outlet. Our results show the added value of combining spatial and temporal tracers to characterize

  7. Evaporation over a Heterogeneous Mixed Savanna-Agricultural Catchment using a Distributed Wireless Sensor Network

    NASA Astrophysics Data System (ADS)

    Ceperley, N. C.; Mande, T.; Barrenetxea, G.; Vetterli, M.; Yacouba, H.; Repetti, A.; Parlange, M. B.

    2010-12-01

    Small scale rain fed agriculture is the primary livelihood for a large part of the population of Burkina Faso. Regional climate change means that this population is becoming increasingly vulnerable. Additionally, as natural savanna is converted for agriculture, hydrological systems are observed to become less stable as infiltration is decreased and rapid runoff is increased to the detriment of crop productivity, downstream populations and local water sources. The majority of the Singou River Basin, located in South East Burkina Faso is managed by hunting reserves, geared to maintaining high populations of wild game; however, residents surrounding the protected areas have been forced to intensify agriculture that has resulted in soil degradation as well as increases in the frequency and severity of flooding and droughts. Agroforestry, or planting trees in cultivated fields, has been proposed as a solution to help buffer these negative consequences, however the specific hydrologic behavior of the watershed land cover is unknown. We have installed a distributed sensor network of 17 Sensorscope wireless meteorological stations. These stations are dispersed across cultivated rice and millet fields, natural savanna, fallow fields, and around agroforestry fields. Sensorscope routes data through the network of stations to be delivered by a GPRS connection to a main server. This multi hop network allows data to be gathered over a large area and quickly adapts to changes in station performance. Data are available in real time via a website that can be accessed by a mobile phone. The stations are powered autonomously by small photovoltaic panels. This deployment is the first time that these meteorological stations have been used on the African continent. Initial calibration with measures from 2 eddy covariance stations allows us to calculate the energy balance at each of the Sensorscope stations. Thus, we can observe variation in evaporation over the various land cover in the

  8. Contrasted distribution of colloidal and true dissolved phosphorus in shallow groundwaters from a small, lowland agricultural catchment

    NASA Astrophysics Data System (ADS)

    GU, S.; Gruau, G.; Dupas, R.; Rivard, C.; Gascuel-odoux, C.; Dorioz, J. M.

    2015-12-01

    Colloids (1~1000 nm) are major phosphorus (P) carrier phases in agricultural soils. Most studies developed so far on the role of colloids in P transport have however focused on laboratory extracted colloids with only little attention being paid to natural soil solutions. Here, we monitored P speciation in natural soil solutions along two transects in a small, agricultural catchment located in Western France, during one hydrological year. We compared the P speciation in these solutions (<0.45 μm) with that of P in lab solutions (NaCl 0.001 M) obtained from the same soil samples, using different speciation techniques, including ultrafiltration combined with inductively coupled plasma mass spectrometry (UF-ICP-MS) and XANES spectroscopy. XANES data evidenced no difference in terms of P speciation between lab extracted colloids and bulk soil samples, however revealing a strong enrichment of P in extracted colloids, thereby confirming the role of colloids as a major P carrier phase in agricultural soils. In natural soil solutions, total dissolved P concentrations (TDP) were similar in transect K and G, while molybdate reactive dissolved P (MRDP) was nearly 10 times higher in transect G than in Transect K. UF-ICP-MS data showed that the natural and lab extracted colloids consisted of a homogeneous mixture of Fe(Al)-oxides and organic matter, despite strong spatial variations of colloidal P proportion in natural waters (from 25 to 70%). Overall, transect G waters showed high proportions of truly-dissolved MRDP (up to 65%), waters in Transect K being richer in colloidal P and truly-dissolved organic P (OP). Lab extractions, however, did not reveal the same difference in P speciation, all the extracts being dominated by colloidal P and MRDP in roughly the same proportions. So far, the cause of this difference is not clearly identified. Though confirming the important role of colloids as a major P carrier phase in agricultural soils, this study indicates that natural soil

  9. Risk assessment of surface water and groundwater pollution through agricultural activity on the catchment area of the Shelek River

    NASA Astrophysics Data System (ADS)

    Zubairov, Bulat; Dautova, Assel

    2015-04-01

    Agricultural activity in rural areas of Kazakhstan can create a potential risk of surface and groundwater pollution. In our contribution, we will focus on the risk assessment of surface water and groundwater pollution in the catchment area of the Shelek River basin in southeast Kazakhstan. Since soviet time, in the research area an intensive cultivation of tobacco was performed which means to use a big amount of pesticides during the growing-process. Therefore, this research was conducted in order to receive reliable data for management decisions justification and for practical testing of approach which is recommended by WHO for drinking water supply based on risks mapping. For our study, the soil and water samples from tobacco fields, artesian spring, and surface water source were taken for analysis on pesticides content. The samples were investigated in laboratory of Centre of Sanitary and Epidemiological Expertise of Almaty city (CSEE) according to approved methods from the national standards which are accepted in Kazakhstan. For the first time, in artesian spring small amount of nitrate pollution was found whose groundwater is one of the drinking water supplies of the region.

  10. Mapping Zn, Cu and Cd contents at the small catchment level after dispersion of contaminants by agricultural practices

    NASA Astrophysics Data System (ADS)

    Vidal Vázquez, E.; Mirás-Avalos, J. M.; Paz-Ferreiro, J.

    2009-04-01

    Dispersion of trace metals into the rural environment through the use of sewage sludge, fertilizers and manure has been worldwide reported. In El Abelar (Coruña province, Spain), pig slurry was discharged during years intensively into an agricultural field by means of a device which constituted a point source of contamination. The application point was located near the head of an elementary basin, so that slurry was dispersed by runoff into neighboring grassland and maize fields. In addition, diffuse pollution was also present in the study area as a consequence of cattle grazing. Water quality was monitored during and after slurry application at the outlet of a small catchment (about 10.7 ha in surface) draining the study fields. High levels of nutrients, including heavy metals, were found in drainage water. The main objectives of this paper are to determine the spatial variability of Cu, Zn and Cd as extracted by NO3H, EDTA and Ca2Cl and to evaluate the risk of accumulation of these heavy metals at the small catchment level. A set of 55 soil samples were taken from the top soil layer (0-20 cm) of the studied catchment, following a random sampling scheme. Fe, Mn, Cu, Zn and Cd contents were determined i) after digestion by nitric acid in a microwave (USEPA-SW-846 3051) ii) after extraction with EDTA and iii) after extraction with Cl2Ca. Element contents in the extracts were determined by ICP-MS. Summary statistics indicate that variability in Cu, Zn and Cd contents over the study area was very high. For example, after NO3H digestion Zn contents ranged from 29.66 to 141.77 3 mg kg-1 and Cu contents varied from 10.45 to 72.7 3 mg kg-1. High Cu and Zn contents result from accumulation as a consequence of slurry discharge. Also, some hot spots with high levels of Cd (> 3 mg kg-1 after NO3H) with respect to background values were recorded. Geostatistics provides all necessary tools to analyze the spatial variability of soil properties over a landscape. The spatial

  11. Comparing three gap filling methods for eddy covariance crop evapotranspiration measurements within a hilly agricultural catchment

    NASA Astrophysics Data System (ADS)

    Boudhina, Nissaf; Prévot, Laurent; Zitouna Chebbi, Rim; Mekki, Insaf; Jacob, Frédéric; Ben Mechlia, Netij; Masmoudi, Moncef

    2015-04-01

    Hilly watersheds are widespread throughout coastal areas around the Mediterranean Basin. They experience agricultural intensification since hilly topographies allow water-harvesting techniques that compensate for rainfall storage, water being a strong limiting factor for crop production. Their fragility is likely to increase with climate change and human pressure. Within semi-arid hilly watershed conditions, evapotranspiration (ETR) is a major term of both land surface energy and water balances. Several methods allow determining ETR, based either on direct measurements, or on estimations and forecast from weather and soil moisture data using simulation models. Among these methods, eddy covariance technique is based on high-frequency measurements of fluctuations of wind speed and air temperature / humidity, to directly determine the convective fluxes between land surface and atmosphere. In spite of experimental and instrumental progresses, datasets of eddy covariance measurements often experience large portions of missing data. The latter results from energy power failure, experimental maintenance, instrumental troubles such as krypton hygrometer malfunctioning because of air humidity, or quality assessment based filtering in relation to spatial homogeneity and temporal stationarity of turbulence within surface boundary layer. This last item is all the more important as hilly topography, when combined with strong winds, tends to increase turbulence within surface boundary layer. The main objective of this study is to establish gap-filling procedures to provide complete chronicles of eddy-covariance measurements of crop evapotranspiration (ETR) within a hilly agricultural watershed. We focus on the specific conditions induced by the combination of hilly topography and wind direction, by discriminating between upslope and downslope winds. The experiment was set for three field configurations within hilly conditions: two flux measurement stations (A, B) were installed

  12. Water and Nutrient Balances in a Large Tile-Drained Agricultural Catchment: A Distributed Modeling Study

    SciTech Connect

    Li, Hongyi; Sivapalan, Murugesu; Tian, Fuqiang; Liu, Dengfeng

    2010-11-16

    This paper presents the development and implementation of a distributed model of coupled water nutrient processes, based on the representative elementary watershed (REW) approach, to the Upper Sangamon River Basin, a large, tile-drained agricultural basin located in central Illinois, mid-west of USA. Comparison of model predictions with the observed hydrological and biogeochemical data, as well as regional estimates from literature studies, shows that the model is capable of capturing the dynamics of water, sediment and nutrient cycles reasonably well. The model is then used as a tool to gain insights into the physical and chemical processes underlying the inter- and intra-annual variability of water and nutrient balances. Model predictions show that about 80% of annual runoff is contributed by tile drainage, while the remainder comes from surface runoff (mainly saturation excess flow) and subsurface runoff. It is also found that, at the annual scale nitrogen storage in the soil is depleted during wet years, and is supplemented during dry years. This carryover of nitrogen storage from dry year to wet year is mainly caused by the lateral loading of nitrate. Phosphorus storage, on the other hand, is not affected much by wet/dry conditions simply because the leaching of it is very minor compared to the other mechanisms taking phosphorous out of the basin, such as crop harvest. The analysis then turned to the movement of nitrate with runoff. Model results suggested that nitrate loading from hillslope into the channel is preferentially carried by tile drainage. Once in the stream it is then subject to in-stream denitrification, the significant spatio-temporal variability of which can be related to the variation of the hydrologic and hydraulic conditions across the river network.

  13. Evaluating stream sediment chemistry within an agricultural catchment of Lebanon, Northeastern USA.

    PubMed

    Oyewumi, Oluyinka; Feldman, Jonathan; Gourley, Jonathan R

    2017-04-01

    Recent arsenic pollution of drinking-water wells across Lebanon, northeastern USA has led to a growing concern about possible impact of agricultural activities on the hydrologic system. This study assessed the concentrations and distributions of arsenic and ten other elements (Al, Cd, Cr, Cu, Fe, K, Mn, P, Pb, and Zn) in stream sediments. The overall goal is to determine the extent of these elements within the fluvial systems, as well as overall sediment quality. A total of 65 stream sediments samples were collected, and analyzed for particle size distributions, organic matter contents, trace, and major elements concentrations. Results showed spatial variability in the concentrations of trace elements due to variation in sediments grain sizes, organic matter content, as well as land use activities within the study area. Calculation of sediment enrichment with respect to As, Cd, Cr, Cu, Mn, Pb, and Zn showed that about 48-52% of all the sampling locations are not enriched, nevertheless, approximately 2-11% of all the sampling locations are significantly enriched, an indication of anthropogenic input. However, results of ecological risk assessment showed no connection with sediment enrichment as most sampling locations have concentrations below the threshold probable effect concentration (PEC) value. Statistical analysis using principal component analysis (PCA) extracted three significant components explaining over 72% of total variance covering elements having origin in both natural and anthropogenic sources, thus suggesting that the concentrations and distribution of these elements within stream sediments are related to a combination of weathering processes on the bedrock geology, and anthropogenic activities.

  14. How old is upland catchment water?

    NASA Astrophysics Data System (ADS)

    Hofmann, Harald; Cartwright, Ian; Morgenstern, Uwe; Gilfedder, Benjamin

    2014-05-01

    Understanding the dynamics of water supply catchments is an essential part of water management. Upland catchments provide a continuous, reliable source of high quality water not only for some of the world's biggest cities, but also for agriculture and industry. Headwater streams control river flow in lowland agricultural basins as the majority of river discharge emerges from upland catchments. Many rivers are perennial and flow throughout the year, even during droughts. However, it is still unclear how reliable and continuous upland catchment water resources really are. Despite many efforts in upland catchment research, there is still little known about where the water is stored and how long it takes to travel through upper catchments. Resolving these questions is crucial to ensure that this resource is protected from changing land use and to estimate potential impacts from a changing climate. Previous research in this important area has been limited by existing measurement techniques. Knowledge to date has relied heavily on the use of variation in stable isotope signals to estimate the age and origin of water from upland catchments. The problem with relying on these measures is that as the water residence time increases, the variation in the stable isotope signal decreases. After a maximum period of four years, no variation can be detected This means that to date, the residence time in upland catchments is likely to have been vastly underestimated. Consequently, the proportion of water flow out of upland river catchments to the total river flow is also underestimated. Tritium (3H) combines directly with water molecules and enters the flow paths with the infiltrating water. Its half-life (12.32 years) makes it ideal to describe residence times in upper catchment reservoirs as it can theoretically measure water up to about 150 years old. The bomb pulse peak in the southern hemisphere was several orders of magnitude lower than in the northern hemisphere. Hence the

  15. Sulfonylurea herbicides in an agricultural catchment basin and its adjacent wetland in the St. Lawrence River basin.

    PubMed

    de Lafontaine, Yves; Beauvais, Conrad; Cessna, Allan J; Gagnon, Pierre; Hudon, Christiane; Poissant, Laurier

    2014-05-01

    The use of sulfonylurea herbicides (SU) has increased greater than 100 times over the past 30 years in both Europe and North America. Applied at low rates, their presence, persistence and potential impacts on aquatic ecosystems remain poorly studied. During late-spring to early fall in 2009-2011, concentrations of 9 SU were assessed in two agricultural streams and their receiving wetland, an enlargement of the St. Lawrence River (Canada). Six SU in concentrations >LOQ (10 ng L(-1)) were detected in 10% or less of surface water samples. Rimsulfuron was detected each year, sulfosulfuron and nicosulfuron in two years and the others in one year only, suggesting that application of specific herbicides varied locally between years. Detection frequency and concentrations of SU were not significantly associated with total precipitation which occurred 1 to 5d before sampling. Concentrations and fate of SU differed among sites due to differences in stream dynamics and water quality characteristics. The persistence of SU in catchment basin streams reflected the dissipation effects associated with stream discharge. Maximum concentrations of some SU (223 and 148 ng L(-1)) were occasionally above the baseline level (100 ng L(-1)) for aquatic plant toxicity, implying potential toxic stress to flora in the streams. Substantially lower concentrations (max 55 ng L(-1)) of SU were noted at the downstream wetland site, likely as a result from dilution and mixing with St. Lawrence River water, and represent less toxicological risk to the wetland flora. Sporadic occurrence of SU at low concentrations in air and rain samples indicated that atmospheric deposition was not an important source of herbicides to the study area.

  16. Nitrous oxide and methane emission in an artificial wetland treating polluted runoff from an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Mander, Ülo; Tournebize, Julien; Soosaar, Kaido; Chaumont, Cedric; Hansen, Raili; Muhel, Mart; Teemusk, Alar; Vincent, Bernard

    2015-04-01

    An artificial wetland built in 2010 to reduce water pollution in a drained agricultural watershed showed real potential for pesticide and nitrate removal. The 1.2 ha off-shore wetland with a depth of from 0.1 to 1 m intercepts drainage water from a 450 ha watershed located near the village of Rampillon (03°03'37.3'' E, 48°32'16.7'' N, 70 km south-east of Paris, France). A sluice gate installed at the inlet makes it possible to close the wetland during the winter months (December - March), when no pesticides are applied and rainfall events are more frequent. The flow entering the wetland fluctuates from 0 to 120 L/s. The wetland is partially covered by Carex spp., Phragmites australis, Juncus conglomeratus, Typha latifolia and philamentous algae. Since 2011, an automatic water quality monitoring system measures water discharge, temperature, dissolved O2, conductivity pH, NO3- and DOC in both inlet and outlet. In May 2014, an automatic weather station and Campbell Irgason system for the measurement of CO2 and H2O fluxes were installed in the middle of the wetland. In May and November 2014 one-week high frequency measurement campaigns were conducted to study N2O and CH4 fluxes using 6 manually operated opaque floating static chambers and 12 floating automatic dynamic chambers. The latter were operated via multiplexer and had an incubation time of 5 minutes, whereas the gas flow was continuously measured using the Aerodyne TILDAS quantum cascade laser system. During the campaign, the reduction of NO3- concentration was measured in nine reactor pipes. Also, water samples were collected for N2O and N2 isotope analysis, and sediments were collected for potential N2 emission measurements. In May, the hydraulic retention time (HRT) was 30 days, and the average NO3- concentration decreased from 24 in the inflow to 0 mg/L in the outflow. Methane flux was relatively high (average 1446, variation 0.2-113990 μg CH4-C m-2 h-1), while about 2/3 was emitted via ebullition

  17. Groundwater Head Control of Catchment Nitrate Export

    NASA Astrophysics Data System (ADS)

    Musolff, A.; Schmidt, C.; Rode, M.; Fleckenstein, J. H.

    2014-12-01

    Elevated nutrient fluxes from agricultural catchments affect downstream water resources. A method to assess nutrient fluxes is the evaluation of the export regime. The export regime classifies the relation between concentration and discharge and integrates mobilization as well as retention processes. Solutes can be exported chemostatically (variance of concentration << variance of discharge) or chemodynamically (variance of concentration ≥ variance of discharge). Starting point of this study is the evaluation of export regimes of nitrate in a series of neighboring sub-catchments of the Central German River Bode catchment. We found an accretion pattern of nitrate with increasing concentration when discharge is increasing and thus a chemodynamic export regime. Here we follow a nested approach and have a closer look at the controls of nitrate export in the small (1.4 km2) headwater catchment of the Sauerbach stream. The Sauerbach catchment is dominated by agricultural land use and is characterized by tile drains. We hypothesize that discharge as well as nitrate export is controlled by the groundwater head variability over time. To that end we follow a joint data analysis of discharge, groundwater heads and nitrate concentrations in groundwater, tile drains and surface water. At the gauging station the nitrate export is chemodynamic exhibiting the typical accretion pattern also found at the larger scale. Our data analysis shows that nitrate export regime is in two ways controlled by the depth to groundwater and the groundwater head variability: Discharge increases with increasing groundwater heads due to the activation of tile drains. On the other hand, depth to groundwater and passage through the unsaturated zone is the major control of aquifer nitrate concentration. At wells with larger depth to groundwater nitrate concentrations are significantly lower than at more shallow wells indicating retention processes in the unsaturated zone. Therefore the concentration in

  18. Assessing the impacts of Best Management Practices on nitrate pollution in an agricultural dominated lowland catchment considering environmental protection versus economic development.

    PubMed

    Haas, Marcelo B; Guse, Björn; Fohrer, Nicola

    2017-03-15

    Water quality is strongly affected by nitrate inputs in agricultural catchments. Best Management Practices (BMPs) are alternative practices aiming to mitigate the impacts derived from agricultural activities and to improve water quality. Management activities are influenced by different governmental policies like the Water Framework Directive (WFD) and the Renewable Energy Sources Act (EEG). Their distinct goals can be contrasting and hamper an integrated sustainable development. Both need to be addressed in the actual conjuncture in rural areas. Ecohydrological models like the SWAT model are important tools for land cover and land use changes investigation and the assessment of BMPs implementation effects on water quality. Thus, in this study, buffer strip, fertilization reduction and alternative crops were considered as BMPs and were implemented in the SWAT model for the Treene catchment. Their efficiency in terms of nitrate loads reduction related to implementation costs at the catchment scale was investigated. The practices correspond to the catchment conditions and are based on small and mid areal changes. Furthermore, the BMPs were evaluated from the perspective of ecologic and economic policies. The results evidenced different responses of the BMPs. The critical periods in winter were addressed by most of the BMPs. However, some practices like pasture land increase need to be implemented in greater area for better results in comparison to current activities. Furthermore, there is a greater nitrate reduction potential by combining BMPs containing fertilization reduction, buffer strips and soil coverage in winter. The discussion about efficiency showed the complexity of costs stipulation and the relation with arable land and yield losses. Furthermore, as the government policies can be divergent an integrated approach considering all the involved actors is important and seeks a sustainable development.

  19. Interactive Effects of Storms, Drought, and Weekly Land Cover Changes on Water Quality Patterns in an Agricultural-dominated Subtropical Catchment in New Zealand

    NASA Astrophysics Data System (ADS)

    Julian, J.; Owsley, B.; de Beurs, K.; Hughes, A.

    2013-12-01

    Rivers are the funnels of landscapes, with the quality of water at the catchment outlet reflecting interactions among geomorphic processes, vegetation characteristics, weather patterns, and anthropogenic land uses. The impacts of changing climate and land cover on water quality are not straightforward; but instead, are set by the interaction of numerous landscape components at multiple spatiotemporal scales. In agricultural-dominated subtropical landscapes such as the Hoteo River Catchment in northern North Island of New Zealand, the land surface can be very dynamic, responding quickly to storms, drought, forest clearings, and grazing practices. In order to capture these short-term fluctuations, we created an 8-day land disturbance index for the catchment using MODIS Nadir BRDF-adjusted reflectance (NBAR) data (500 meter resolution) from 2000 to 2013. We also fused this time-series with Landsat TM/ETM surface reflectance data (30 meter resolution) to more precisely capture the location and extent of these land disturbances. This high-resolution land disturbance time-series was then compared to daily rainfall, daily river discharge, and monthly water samples to assess the effects of changing weather and land cover on a suite of water quality variables including water clarity, turbidity, ammonium (NH4), nitrate (NO3), total nitrogen (TN), dissolved reactive phosphate (DRP), total phosphorus (TP), and fecal coliforms. Forest clearings in the early part of our study period created the most intense land disturbances, which led to elevated turbidity and DRP during subsequent storms. Pasture areas during drought were also characterized by high disturbance indices, particularly in 2013 - the worst drought on record for northern New Zealand. Seasonal effects on land disturbance and water quality were also detected, especially for water clarity and turbidity. From 2011 to 2013, river discharge and turbidity from three sub-catchments were measured at 5-minute intervals to

  20. Indirect nitrous oxide emissions from surface water bodies in a lowland arable catchment: a significant contribution to agricultural greenhouse gas budgets?

    PubMed

    Outram, Faye N; Hiscock, Kevin M

    2012-08-07

    In the UK agriculture is by far the largest source of nitrous oxide (N(2)O) emissions. Direct N(2)O emissions as a result of nitrogen (N) application to soils have been well documented in the UK, whereas indirect emissions produced in surface waters and groundwaters from leached N are much less understood with limited data to support IPCC emission factors. Indirect emissions were studied in surface waters in the Upper Thurne, a lowland drained arable catchment in eastern England. All surface waters were found to have dissolved N(2)O concentrations above that expected if in equilibrium with ambient concentrations, demonstrating all surface waters were acting as a source of N(2)O. The drainage channels represented 86% of the total indirect N(2)O flux, followed by wetland areas, 11%, and the river, 3%. The dense drainage network was found to have the highest dissolved N(2)O concentrations of all the water bodies studied with a combined N(2)O flux of 16 kg N(2)O-N per day in March 2007. Such indirect fluxes are comparable to direct fluxes per hectare and represent a significant proportion of the total N(2)O flux for this catchment. Separate emission factors were established for the three different surface water types within the same catchment, suggesting that the one emission factor used in the Intergovernmental Panel on Climate Change (IPCC) methodology for predicting all indirect N(2)O emissions is inappropriate.

  1. REXPO: A catchment model designed to understand and simulate the loss dynamics of plant protection products and biocides from agricultural and urban areas

    NASA Astrophysics Data System (ADS)

    Wittmer, I. K.; Bader, H.-P.; Scheidegger, R.; Stamm, C.

    2016-02-01

    During rain events, biocides and plant protection products are transported from agricultural fields but also from urban sources to surface waters. Originally designed to be biologically active, these compounds may harm organisms in aquatic ecosystems. Although several models allow either urban or agricultural storm events to be predicted, only few combine these two sources, and none of them include biocide losses from building envelopes. This study therefore aims to develop a model designed to predict water and substance flows from urban and agricultural sources to surface waters. We developed a model based on physical principles for water percolation and substance flow including micro- (also called matrix-) and macropore-flows for the agricultural areas together with a model representing sources, sewer systems and a wastewater treatment plant for urban areas. In a second step, the combined model was applied to a catchment where an extensive field study had been conducted. The modelled and measured discharge and compound results corresponded reasonably well in terms of quantity and dynamics. The total cumulative discharge was only slightly lower than the total measured discharge (factor 0.94). The total modelled losses of the agriculturally used herbicide atrazine were slightly lower (∼25%) than the measured losses when the soil pore water distribution coefficient (describing the partition between soil particles and pore water) (Kd) was kept constant and slightly higher if it was increased with time. The modelled urban losses of diuron from facades were within a factor of three with respect to the measured values. The results highlighted the change in importance of the flow components during a rain event from urban sources during the most intensive rain period towards agricultural ones over a prolonged time period. Applications to two other catchments, one neighbouring and one on another continent showed that the model can be applied using site specific data for

  2. Spatial and temporal variations in non-point source losses of nitrogen and phosphorus in a small agricultural catchment in the Three Gorges Region.

    PubMed

    Chen, Chenglong; Gao, Ming; Xie, Deti; Ni, Jiupai

    2016-04-01

    Losses of agricultural pollutants from small catchments are a major issue for water quality in the Three Gorges Region. Solutions are urgently needed. However, before pollutant losses can be controlled, information about spatial and temporal variations in pollutant losses is needed. The study was carried out in the Wangjiagou catchment, a small agricultural catchment in Fuling District, Chongqing, and the data about non-point source losses of nitrogen and phosphorus was collected here. Water samples were collected daily by an automatic water sampler at the outlets of two subcatchments from 2012 to 2014. Also, samples of surface runoff from 28 sampling sites distributed through the subcatchments were collected during 12 rainfall events in 2014. A range of water quality variables were analyzed for all samples and were used to demonstrate the variation in non-point losses of nitrogen and phosphorus over a range of temporal and spatial scales and in different types of rainfall in the catchment. Results showed that there was a significant linear correlation between the mass concentrations of total nitrogen (TN) and nitrate (NO3-N) in surface runoff and that the relationship was maintained with changes in time. Concentrations of TN and NO3-N peaked after fertilizer was applied to crops in spring and autumn; concentrations decreased rapidly after the peak values in spring but declined slowly in autumn. N and P concentrations fluctuated more and showed a greater degree of dispersion during the spring crop cultivation period than those in autumn. Concentrations of TN and NO3-N in surface runoff were significantly and positively correlated with the proportion of the area that was planted with corn and mustard tubers, but were negatively correlated with the proportion of the area taken up with rice and mulberry plantations. The average concentrations of TN and NO3-N in surface runoff reached the highest level from the sampling points at the bottom of the land used for corn

  3. Impacts of land use and climate variability on hydrology in an agricultural catchment on the Loess Plateau of China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land use and climate are the two major factors directly influencing catchment hydrology; however, it is difficult to separate the effects of the two. Using the SWAT (Soil and Water Assessment Tools) model, we assessed the impacts of land use change and climate variability on surface hydrology (runof...

  4. Dissolved and Particulate Organic Carbon Transport, Loads and Relationships from Catchments in the Dryland Agricultural Region of the Inland Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Boylan, R. D.; Brooks, E. S.

    2012-12-01

    It has long been understood that soil organic matter (SOM) plays important role in the chemistry of agricultural soils. Promoting both cation exchange capacity and water retention, SOM also has the ability to sequester atmospheric carbon adding to a soils organic carbon content. Increasing soil organic carbon in the dryland agricultural region of the Inland Pacific Northwest is not only good for soil health, but also has the potential to mitigate greenhouse gas emissions. Implementing strategies that minimizing the loss of soil carbon thus promoting carbon sequestration require a fundamental understanding of the dominant hydrologic flow paths and runoff generating processes in this landscape. Global fluxes of organic carbon from catchments range from 0.4-73,979 kg C km-2 year-1 for particulate organic carbon and 1.2-56,946 kg C km-2 year-1 for dissolved organic carbon (Alvarez-Cobelas, 2010). This small component of the global carbon cycle has been relatively well studied but there have yet to be any studies that focus on the dryland agricultural region of the Inland Pacific Northwest. In this study event based samples were taken at 5 sites across the Palouse Basin varying in land use and management type as well as catchment size, ranging from 1km2 to 7000 km2. Data collection includes streamflow, suspended sediment, dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), particulate organic carbon (POC), dissolved organic nitrogen (TN), and nitrate concentrations as well as soil organic carbon (SOC) from distributed source areas. It is predicted that management type and streamflow will be the main drivers for DOC and POC concentrations. Relationships generated and historic data will then be used in conjunction with the Water Erosion Prediction Project (WEPP) to simulate field scale variability in the soil moisture, temperature, surface saturation, and soil erosion. Model assessment will be based on both surface runoff and sediment load measured at the

  5. Carbon-, nitrogen- and water-fluxes of agricultural landuse types in the Upper Danube catchment under global change: integrating natural and agroeconomic effects

    NASA Astrophysics Data System (ADS)

    Reichenau, Tim G.; Klar, Christian W.; Fiener, Peter; Schneider, Karl

    2010-05-01

    Climate change will not only modify water, carbon and nitrogen fluxes of agricultural ecosystems as a result of the direct impact of climate parameters. The adaption of farming practices (e.g. time of management activities, selection of crops) will also affect theses fluxes. An important driver for changes in agricultural management is the improvement of economical viability which requires both the optimization of the spatial distribution of crops over arable land and the adjustment of cultivation procedures. Thus, investigating climate change effects for agricultural land use types requires that both, direct natural and indirect anthropogenic effects, must be accounted for. The model assembly 'agriculture' within the DANUBIA decision support system has been designed to assess interactions between environmental and anthropogenic effects of climate change. It consists of dynamically interacting models describing plant growth, soil nitrogen transformation, water- and energy-fluxes. In addition, a farm-actor model simulating management activities and economic decisions concerning agricultural land use is coupled to the environmental models. Thus the model assembly 'agriculture' allows for the analysis of environmental and agro-economic effects as well as for the feedbacks between these effects. In this study changes in transpiration, biomass production and nitrogen uptake for two different agro-political scenarios area analyzed: a 'baseline' scenario assuming unchanged agropolitics and a 'performance' scenario, where the payment of agricultural subsidies ends in 2015. Two exemplarily districts with contrasting agricultural land use were examined. Dingolfing in the northeastern part of the Upper Danube catchment is dominated by arable land, whereas in Ostallgäu in the southwest region of the catchment grassland prevails. The model was run for the period 2011 till 2058 assuming a climate scenario based on the IPPC A1B emission scenario. Ten year averages for the

  6. Urban and agricultural contribution of annual loads of glyphosate and AMPA towards surface waters at the Orge River catchment scale (France)

    NASA Astrophysics Data System (ADS)

    Botta, Fabrizio; Chevreuil, Marc; Blanchoud, Hélène

    2010-05-01

    The general use of pesticides in the Orge Basin, located in the southern part of the Paris suburb (France), is damaging surface water quality. Consequently, an increase in the water supply costs is registered by the water supply agencies that are situated downstream the Orge confluence with the Seine River. In this catchment, high uses of glyphosate are registered for fallow fields (upstream part) and for roadway weed control (downstream part). The proportion of glyphosate coming from these two zones was not well known, along with the double source of its metabolite AMPA originated from the degradation of some detergent phosphonates. The aim of this work was firstly to identify the potential sources of glyphosate and AMPA in urban sectors (such as sewerage system inputs) and in agricultural areas and to quantify the origins of urban pesticides pathways towards surface waters at the basin scale. The new approach of this project was to collect information at three different scales to establish a first step of modeling. At the basin scale, 1 year of surface water monitoring at the outlet of the Orge River was useful to establish the inputs towards the Seine River. At the urban catchment scale, the investigations have permitted to record glyphosate and AMPA loads transferred by storm waters and by wastewaters. Loads were estimated during and out of application calendar, in different hydrological conditions such as rainfall with high intensity or dry conditions. Impact of WWTP on surface water was also demonstrated. The third phase of this work was the interpretation of agricultural inputs from two different agricultural catchments of the Orge River. The results showed the impact of urban uses of glyphosate upon the Orge River contamination with annual loads from 100 times higher from the urban zone than from the agricultural one. Storm sewers were recognized to be the main way for glyphosate transfer towards surface waters. A budget of glyphosate and AMPA inputs and

  7. Contaminated sediment dynamics in peatland headwaters

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Clay, Gareth; Evans, Martin; Hutchinson, Simon; Rothwell, James

    2016-04-01

    Peatlands are an important store of soil carbon, provide multiple ecosystem services, and when located in close proximity to urban and industrial areas, can also act as sinks of atmospherically deposited heavy metals. The near-surface layer of the blanket peats of the Peak District National Park, UK, is severely contaminated with high concentrations of anthropogenically derived, atmospherically deposited lead (Pb). These peats are severely degraded, and there is increasing concern that erosion is releasing considerable quantities of this legacy pollution into surface waters. Despite substantial research into Pb dynamics in peatlands formal description of the possible mechanisms of contaminated sediment mobilisation is limited. However, there is evidence to suggest that a substantial proportion of contaminated surface sediment may be redistributed elsewhere in the catchment. This study uses the Pb contamination stored near the peat's surface as a fingerprint to trace contaminated sediment dynamics and storage in three severely degraded headwater catchments. Erosion is exposing high concentrations of Pb on interfluve surfaces, and substantial amounts of reworked contaminated material are stored on other catchment surfaces (gully walls and floors). We propose a variety of mechanisms as controls of Pb release and storage on the different surfaces, including: (i) wind action on interfluves; (ii) the aspect of gully walls, and (iii) gully depth. Vegetation also plays an important role in retaining contaminated sediment on all surfaces.

  8. Controls of catchments` sub-storage contributions to dynamic water quality patterns in the stream network

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Maike Hegenauer, Anja

    2016-04-01

    Water quality is usually observed either continuously at a few stations within a catchment or with few snapshot sampling campaigns throughout the whole stream network. Although we know that the depletion of catchment sub-storages can vary throughout the stream network according to their actual water content (spatial variability of actual storage conditions can be caused amongst others by unevenly distributed rainfall, storage size or spatial differences in soil characteristics and land use), we know little about the impact of this process on spatial water quality patterns. For summer low flow recession periods, when stream water composition can be crucial for aquatic ecosystem conditions and the exceedance of water quality thresholds, knowledge on the controls of the dynamic interplay of catchment storages and stream water composition might improve water quality management and the implementation of corresponding mitigation measures. We studied this process throughout the stream network of a first-order agricultural headwater catchment in south-western Germany during two summer low flow recession periods. The underlying geology of the study area is a deep layer of aeolian loess, whilst the dominating soil is a silty calcaric regosol with gleizations in the colluvium. The land use in the catchment is dominated by viniculture (63 %) and arable crops (18 %). Due to the dense drainpipe network within the catchment we could identify 12 sub-catchments contributing during summer low flow recession periods to total stream discharge. We continuously observed discharge, electrical conductivity and water temperatures for 8 of the sub-catchments and at the catchment outlet. This data set was accomplished by 10 snapshot campaigns where we sampled for water temperatures, electrical conductivity, major ions, pH and O2 throughout the stream network. Using either discharge concentration relationships or time dependent functions, we derived continuous export rates for all measures in

  9. Impact of nitrogenous fertilizers on carbonate dissolution in small agricultural catchments: Implications for weathering CO 2 uptake at regional and global scales

    NASA Astrophysics Data System (ADS)

    Perrin, Anne-Sophie; Probst, Anne; Probst, Jean-Luc

    2008-07-01

    The goal of this study was to highlight the occurrence of an additional proton-promoted weathering pathway of carbonate rocks in agricultural areas where N-fertilizers are extensively spread, and to estimate its consequences on riverine alkalinity and uptake of CO 2 by weathering. We surveyed 25 small streams in the calcareous molassic Gascogne area located in the Garonne river basin (south-western France) that drain cultivated or forested catchments for their major element compositions during different hydrologic periods. Among these catchments, the Hay and the Montoussé, two experimental catchments, were monitored on a weekly basis. Studies in the literature from other small carbonate catchments in Europe were dissected in the same way. In areas of intensive agriculture, the molar ratio (Ca + Mg)/HCO 3 in surface waters is significantly higher (0.7 on average) than in areas of low anthropogenic pressure (0.5). This corresponds to a decrease in riverine alkalinity, which can reach 80% during storm events. This relative loss of alkalinity correlates well with the NO3- content in surface waters. In cultivated areas, the contribution of atmospheric/soil CO 2 to the total riverine alkalinity (CO 2 ATM-SOIL/HCO 3) is less than 50% (expected value for carbonate basins), and it decreases when the nitrate concentration increases. This loss of alkalinity can be attributed to the substitution of carbonic acid (natural weathering pathway) by protons produced by nitrification of N-fertilizers (anthropogenic weathering pathway) occurring in soils during carbonate dissolution. As a consequence of these processes, the alkalinity over the last 30 years shows a decreasing trend in the Save river (one of the main Garonne river tributaries, draining an agricultural catchment), while the nitrate and calcium plus magnesium contents are increasing. We estimated that the contribution of atmospheric/soil CO 2 to riverine alkalinity decreased by about 7-17% on average for all the studied

  10. Sediment sources in a small agricultural catchment: A composite fingerprinting approach based on the selection of potential sources

    NASA Astrophysics Data System (ADS)

    Zhou, Huiping; Chang, Weina; Zhang, Longjiang

    2016-08-01

    Fingerprinting techniques have been widely used as a reasonable and reliable means for investigating sediment sources, especially in relatively large catchments in which there are significant differences in surface materials. However, the discrimination power of fingerprint properties for small catchments, in which the surface materials are relatively homogeneous and human interference is marked, may be affected by fragmentary or confused source information. Using fingerprinting techniques can be difficult, and there is still a need for further studies to verify the effectiveness of such techniques in these small catchments. A composite fingerprinting approach was used in this study to investigate the main sources of sediment output, as well as their relative contributions, from a small catchment (30 km2) with high levels of farming and mining activities. The impact of the selection of different potential sediment sources on the derivation of composite fingerprints and its discrimination power were also investigated by comparing the results from different combinations of potential source types. The initial source types and several samples that could cause confusion were adjusted. These adjustments improved the discrimination power of the composite fingerprints. The results showed that the composite fingerprinting approach used in this study had a discriminatory efficiency of 89.2% for different sediment sources and that the model had a mean goodness of fit of 0.90. Cultivated lands were the main sediment source. The sediment contribution of the studied cultivated lands ranged from 39.9% to 87.8%, with a mean of 76.6%, for multiple deposited sediment samples. The mean contribution of woodlands was 21.7%. Overall, the sediment contribution from mining and road areas was relatively low. The selection of potential sources is an important factor in the application of fingerprinting techniques and warrants more attention in future studies, as is the case with other

  11. Large carbon dioxide fluxes from headwater boreal and sub-boreal streams.

    PubMed

    Venkiteswaran, Jason J; Schiff, Sherry L; Wallin, Marcus B

    2014-01-01

    Half of the world's forest is in boreal and sub-boreal ecozones, containing large carbon stores and fluxes. Carbon lost from headwater streams in these forests is underestimated. We apply a simple stable carbon isotope idea for quantifying the CO2 loss from these small streams; it is based only on in-stream samples and integrates over a significant distance upstream. We demonstrate that conventional methods of determining CO2 loss from streams necessarily underestimate the CO2 loss with results from two catchments. Dissolved carbon export from headwater catchments is similar to CO2 loss from stream surfaces. Most of the CO2 originating in high CO2 groundwaters has been lost before typical in-stream sampling occurs. In the Harp Lake catchment in Canada, headwater streams account for 10% of catchment net CO2 uptake. In the Krycklan catchment in Sweden, this more than doubles the CO2 loss from the catchment. Thus, even when corrected for aquatic CO2 loss measured by conventional methods, boreal and sub-boreal forest carbon budgets currently overestimate carbon sequestration on the landscape.

  12. Assessing the relationship of background factors governing the water quality of an agricultural watershed with changes in catchment property (W-Hungary)

    NASA Astrophysics Data System (ADS)

    Hatvani, István Gábor; Kovács, József; Márkus, László; Clement, Adrienne; Hoffmann, Richárd; Korponai, János

    2015-02-01

    With urbanization and the growth of agriculture, the importance of precisely assessing the contribution of diffuse- and point source loads arriving to surface waters is becoming more and more important. Determining their effects, however, is not as straightforward as it at first seems. The main aim of the study was to determine the driving background factors of a river located in an agricultural watershed, and furthermore, to separate the role of the diffuse- and point source nutrient loads. The method used to achieve the aims was Dynamic Factor Analysis. This is an effective tool for exploring time series which describe such phenomena. It is capable of taking into account the lagged correlation structure, thus enabling the researcher to uncover the background processes operating in time series. Dynamic Factor Analysis was applied to the time series (1978-2006) of 21 response parameters measured in the River Zala and 6 explanatory (agricultural, meteorological, water quality, etc.) parameters measured in its watershed. The results demonstrated that with the aid of Dynamic Factor Analysis the superimposed effects of the socio-economic changes which began in the mid-1980s, and the introduction of advanced wastewater treatment (P removal) in the river catchment in the early 1990s could be separated and their relative importance assessed, as well as that of other determining external factors.

  13. The strategic significance of wastewater sources to pollutant phosphorus levels in English rivers and to environmental management for rural, agricultural and urban catchments.

    PubMed

    Neal, Colin; Jarvie, Helen P; Withers, Paul J A; Whitton, Brian A; Neal, Margaret

    2010-03-01

    The relationship between soluble and particulate phosphorus was examined for 9 major UK rivers including 26 major tributaries and 68 monitoring points, covering wide-ranging rural and agricultural/urban impacted systems with catchment areas varying from 1 to 6000km(2) scales. Phosphorus concentrations in Soluble Reactive (SRP), Total Dissolved (TDP), Total (TP), Dissolved Hydrolysable (DHP) and Particulate (PP) forms correlated with effluent markers (sodium and boron) and SRP was generally dominant signifying the importance of sewage sources. Low flows were particularly enriched in SRP, TDP and TP for average SRP>100microg/l indicating low effluent dilution. At particularly low average concentrations, SRP increased with flow but effluent sources were still implicated as the effluent markers (boron in particular) increased likewise. For rural areas, DHP had proportionately high concentrations and SRP+DHP concentrations could exceed environmental thresholds currently set for SRP. Given DHP has a high bioavailability the environmental implications need further consideration. PP concentrations were generally highest at high flows but PP in the suspended solids was generally at its lowest and in general PP correlated with particulate organic carbon and more so than the suspended sediment in total. Separation of pollutant inputs solely between effluent and diffuse (agriculture) components is misleading, as part of the "diffuse" term comprises effluents flushed from the catchments during high flow. Effluent sources of phosphorus supplied directly or indirectly to the river coupled with within-river interactions between water/sediment/biota largely determine pollutant levels. The study flags the fundamental need of placing direct and indirect effluent sources and contaminated storage with interchange to/from the river at the focus for remediation strategies for UK rivers in relation to eutrophication and the WFD.

  14. Analysing the role of abandoned agricultural terraces on flood generation in a set of small Mediterranean mountain research catchments (Vallcebre, NE Spain)

    NASA Astrophysics Data System (ADS)

    Gallart, Francesc; Llorens, Pilar; Pérez-Gallego, Nuria; Latron, Jérôme

    2016-04-01

    The Vallcebre research catchments are located in NE Spain, in a middle mountain area with a Mediterranean sub-humid climate. Most of the bedrock consists of continental red lutites that are easily weathered into loamy soils. This area was intensely used for agriculture in the past when most of the sunny gentle hillslopes were terraced. The land was progressively abandoned since the mid-20th Century and most of the fields were converted to meadows or were spontaneously forested. Early studies carried out in the terraced Cal Parisa catchment demonstrated the occurrence of two types of frequently saturated areas, ones situated in downslope locations with high topographic index values, and the others located in the inner parts of many terraces, where the shallow water table usually outcrops due to the topographical modifications linked to terrace construction. Both the increased extent of saturated areas and the role of a man-made elementary drainage system designed for depleting water from the terraces suggested that terraced areas would induce an enhanced hydrological response during rainfall events when compared with non-terraced hillslopes. The response of 3 sub-catchments, of increasing area and decreasing percentage of terraced area, during a set of major events collected during over 15 years has been analysed. The results show that storm runoff depths were roughly proportional to precipitations above 30 mm although the smallest catchment (Cal Parisa), with the highest percentage of terraces, was able to completely buffer rainfall events of 60 mm in one hour without any runoff when antecedent conditions were dry. Runoff coefficients depended on antecedent conditions and peak discharges were weakly linked to rainfall intensities. Peak lag times, peak runoff rates and recession coefficients were similar in the 3 catchments; the first variable values were in the range between Hortonian and saturation overland flow and the two last ones were in the range of

  15. Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales

    USGS Publications Warehouse

    Freeman, Mary C.; Pringle, C.M.; Jackson, C.R.

    2007-01-01

    Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large-scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free-flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large-scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream-system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and

  16. Effects of agricultural best-management practices on the Brush Run Creek headwaters, Adams County, Pennsylvania, prior to and during nutrient management

    USGS Publications Warehouse

    Langland, M.J.; Fishel, D.K.

    1996-01-01

    The U.S. Geological Survey, in cooperation with the Susquehanna River Basin Commission and the Pennsylvania Department of Environmental Resources, investigated the effects of agricultural best-management practices on surface-water quality as part of the U.S. Environmental Protection Agency's Chesapeake Bay Program. This report characterizes a 0.63-square- mile agricultural watershed underlain by shale, mudstone, and red arkosic sandstone in the Lower Susquehanna River Basin. The water quality of the Brush Run Creek site was studied from October 1985 through September 1991, prior to and during the implementation of nutrient management designed to reduce sediment and nutrient discharges into Conewago Creek, a tributary to the Chesapeake Bay. The original study area was 0.38 square mile and included an area immediately upstream from a manure lagoon. The study area was increased to 0.63 square mile in the fall of 1987 after an extensive tile-drain network was discovered upstream and downstream from the established streamflow gage, and the farm owner made plans to spray irrigate manure to the downstream fields. Land use for about 64 percent of the 0.63 square mile watershed is cropland, 14 percent is pasture, 7 percent is forest, and the remaining 15 percent is yards, buildings, water, or gardens. About 73 percent of the cropland was used to produce corn during the study. The average annual animal population consisted of 57,000 chickens, 1,530 hogs, and 15 sheep during the study. About 59,340 pounds of nitrogen and 13,710 pounds of phosphorus were applied as manure and commercial fertilizer to fields within the subbasin during the 3-year period prior to implementation of nutrient management. During nutrient management, about 14 percent less nitrogen and 57 percent less phosphorus were applied as commercial and manure fertilizer. Precipitation totaled 209 inches, or 13 percent less than the long-term normal, during the 6-year study. Concentrations of total ammonia in

  17. Selected examples of needs for long term pilot areas in Mediterranean catchments: a mountain traditional agricultural system and a large and regulated hydrographic basin in Southern Spain

    NASA Astrophysics Data System (ADS)

    José Polo, María; Herrero, Javier; Millares, Agustín; José Pérez-Palazón, María; Pimentel, Rafael; Aguilar, Cristina; Jurado, Alicia; Contreras, Eva; Gómez-Beas, Raquel; Carpintero, Miriam; Gulliver, Zacarías

    2015-04-01

    Integrated River Basin Management (IRBM) aims at planning water, land and other natural resources for an equitable and sustainable management, also capable of preserving or restoring freshwater ecosystems. Long term series of significant variables at different scales and a sound knowledge of the river basin processes are needed to establish the current state and past&future evolution of the hydrological system, soil use and vegetation distribution, and their social impacts and feedbacks. This is particularly crucial if future scenario analyses are to be performed to assess decision-making processes and adaptive plans. This work highlights the need for an adequate design and development of process-oriented monitoring systems at the basin scale in a decision-making framework. First, the hydrologic monitoring network of the Guadalfeo River Basin, in the southern face of Sierra Nevada Range (Spain), is shown, in a pilot catchment of 1300 km2 in which snow processes in Mediterranean conditions have been studied over the last ten years with a holistic approach. The network development and the main features of the dataset are described together with their use for different scientific and environmental applications; their benefits for assessing social and economic impact in the rural environment are shown from a study case in which the sustainability of ancient channels fed by snowmelt, in use since the XIIIth century for traditional irrigated crops in the mountainous area, was assessed in a future scenarios analyses. Secondly, the standard flow and water quality monitoring networks in the Guadalquivir River Basin, a large (57400 km2) and highly regulated agricultural catchment in southern Spain, are shown, and their strengths and weaknessess for an IRBM framework are analysed. Sediments and selected pollutants are used to trace soil erosion and agricultural/urban exports throughout the catchment, and the final loads to the river estuary in the Atlantic Ocean are assessed

  18. Land use effects on quality and quantity aspects of water resources in headwater areas of the Jaguari River Basin

    NASA Astrophysics Data System (ADS)

    Figueiredo, R. D. O.; Camargo, P. B. D.; Piccolo, M. C.; Zuccari, M. L.; Ferracini, V. L.; Cruz, P. P. N. D.; Green, T. R.; Costa, C. F. G. D.; Reis, L. D. C.

    2015-12-01

    In the context of the recent drought conditions in southeastern Brazil, EMBRAPA (Brazilian Agricultural Research Corporation) in partnership with two Brazilian universities (USP/CENA and UNIFAL) planned a research project, called BaCaJa, to understand the hydrobiogeochemistry processes that occur in small catchments (<1,000 ha) at the upper portions of the Jaguari River Basin situated on both states of Sao Paulo and Minas Gerais. The approach of this study is based on the fact that the evaluation of stream water quality and quantity is an efficient tool to characterize the sustainability of the agriculture production at a catchment level. Its goal is, therefore, to survey the land use effects on the hydrobiogeochemistry in headwaters areas of the Jaguari River Basin to support sustainable management of water resources in this region. Sampling stations were established on rivers and streams ranging from one to five order channels as well as selected small catchments to conduct studies on overland flow, soil solution, soil quality, aquatic biota and pesticide dynamic. The research team is huge and their goals are specific, diverse and complementary, being summed up as: characterize land use, topography and soils; evaluate erosive potential in agriculture areas; measure soil carbon and nitrogen contents; characterize hydrogeochemistry fluxes; apply hydrological modeling and simulate different land use and management scenarios; monitor possible pesticides contamination; and survey macro invertebrates as indicators of water quality. Based on a synthesis of the results, the project team intends to point out the environmental impacts and contribute recommendations of management for the focused region to conserve water resources in terms of quality and quantity.

  19. River water quality of the River Cherwell: an agricultural clay-dominated catchment in the upper Thames Basin, southeastern England.

    PubMed

    Neal, Colin; Neal, Margaret; Hill, Linda; Wickham, Heather

    2006-05-01

    The water quality of the River Cherwell and a tributary of it, the Ray, are described in terms of point and diffuse sources of pollution, for this rural area of the upper Thames Basin. Point sources of pollution dominate at the critical ecological low flow periods of high biological activity. Although the surface geology is predominantly clay, base flow is partly supplied from springs in underlying carbonate-bearing strata, which influences the water quality particularly with regards to calcium and alkalinity. The hydrogeochemistry of the river is outlined and the overall importance of urban point sources even in what would normally be considered to be rural catchments is stressed in relation to the European Unions Water Framework Directive. Issues of phosphorus stripping at sewage treatment works are also considered: such stripping on the Cherwell has reduced phosphorus concentrations by about a factor of two, but this is insufficient for the needs of the Water Framework Directive.

  20. The Role of Headwater Streams in Downstream Water Quality.

    PubMed

    Alexander, Richard B; Boyer, Elizabeth W; Smith, Richard A; Schwarz, Gregory E; Moore, Richard B

    2007-02-01

    Knowledge of headwater influences on the water-quality and flow conditions of downstream waters is essential to water-resource management at all governmental levels; this includes recent court decisions on the jurisdiction of the Federal Clean Water Act (CWA) over upland areas that contribute to larger downstream water bodies. We review current watershed research and use a water-quality model to investigate headwater influences on downstream receiving waters. Our evaluations demonstrate the intrinsic connections of headwaters to landscape processes and downstream waters through their influence on the supply, transport, and fate of water and solutes in watersheds. Hydrological processes in headwater catchments control the recharge of subsurface water stores, flow paths, and residence times of water throughout landscapes. The dynamic coupling of hydrological and biogeochemical processes in upland streams further controls the chemical form, timing, and longitudinal distances of solute transport to downstream waters. We apply the spatially explicit, mass-balance watershed model SPARROW to consider transport and transformations of water and nutrients throughout stream networks in the northeastern United States. We simulate fluxes of nitrogen, a primary nutrient that is a water-quality concern for acidification of streams and lakes and eutrophication of coastal waters, and refine the model structure to include literature observations of nitrogen removal in streams and lakes. We quantify nitrogen transport from headwaters to downstream navigable waters, where headwaters are defined within the model as first-order, perennial streams that include flow and nitrogen contributions from smaller, intermittent and ephemeral streams. We find that first-order headwaters contribute approximately 70% of the mean-annual water volume and 65% of the nitrogen flux in second-order streams. Their contributions to mean water volume and nitrogen flux decline only marginally to about 55% and

  1. The Role of Headwater Streams in Downstream Water Quality1

    PubMed Central

    Alexander, Richard B; Boyer, Elizabeth W; Smith, Richard A; Schwarz, Gregory E; Moore, Richard B

    2007-01-01

    Knowledge of headwater influences on the water-quality and flow conditions of downstream waters is essential to water-resource management at all governmental levels; this includes recent court decisions on the jurisdiction of the Federal Clean Water Act (CWA) over upland areas that contribute to larger downstream water bodies. We review current watershed research and use a water-quality model to investigate headwater influences on downstream receiving waters. Our evaluations demonstrate the intrinsic connections of headwaters to landscape processes and downstream waters through their influence on the supply, transport, and fate of water and solutes in watersheds. Hydrological processes in headwater catchments control the recharge of subsurface water stores, flow paths, and residence times of water throughout landscapes. The dynamic coupling of hydrological and biogeochemical processes in upland streams further controls the chemical form, timing, and longitudinal distances of solute transport to downstream waters. We apply the spatially explicit, mass-balance watershed model SPARROW to consider transport and transformations of water and nutrients throughout stream networks in the northeastern United States. We simulate fluxes of nitrogen, a primary nutrient that is a water-quality concern for acidification of streams and lakes and eutrophication of coastal waters, and refine the model structure to include literature observations of nitrogen removal in streams and lakes. We quantify nitrogen transport from headwaters to downstream navigable waters, where headwaters are defined within the model as first-order, perennial streams that include flow and nitrogen contributions from smaller, intermittent and ephemeral streams. We find that first-order headwaters contribute approximately 70% of the mean-annual water volume and 65% of the nitrogen flux in second-order streams. Their contributions to mean water volume and nitrogen flux decline only marginally to about 55% and

  2. The role of headwater streams in downstream water quality

    USGS Publications Warehouse

    Alexander, R.B.; Boyer, E.W.; Smith, R.A.; Schwarz, G.E.; Moore, R.B.

    2007-01-01

    Knowledge of headwater influences on the water-quality and flow conditions of downstream waters is essential to water-resource management at all governmental levels; this includes recent court decisions on the jurisdiction of the Federal Clean Water Act (CWA) over upland areas that contribute to larger downstream water bodies. We review current watershed research and use a water-quality model to investigate headwater influences on downstream receiving waters. Our evaluations demonstrate the intrinsic connections of headwaters to landscape processes and downstream waters through their influence on the supply, transport, and fate of water and solutes in watersheds. Hydrological processes in headwater catchments control the recharge of subsurface water stores, flow paths, and residence times of water throughout landscapes. The dynamic coupling of hydrological and biogeochemical processes in upland streams further controls the chemical form, timing, and longitudinal distances of solute transport to downstream waters. We apply the spatially explicit, mass-balance watershed model SPARROW to consider transport and transformations of water and nutrients throughout stream networks in the northeastern United States. We simulate fluxes of nitrogen, a primary nutrient that is a water-quality concern for acidification of streams and lakes and eutrophication of coastal waters, and refine the model structure to include literature observations of nitrogen removal in streams and lakes. We quantify nitrogen transport from headwaters to downstream navigable waters, where headwaters are defined within the model as first-order, perennial streams that include flow and nitrogen contributions from smaller, intermittent and ephemeral streams. We find that first-order headwaters contribute approximately 70% of the mean-annual water volume and 65% of the nitrogen flux in second-order streams. Their contributions to mean water volume and nitrogen flux decline only marginally to about 55% and

  3. Catchment systems science and management: from evidence to resilient landscapes

    NASA Astrophysics Data System (ADS)

    Quinn, Paul

    2014-05-01

    There is an urgent need to reassess both the scientific understanding and the policy making approaches taken to manage flooding, water scarcity and pollution in intensively utilised catchments. Many European catchments have been heavily modified and natural systems have largely disappeared. However, working with natural processes must still be at the core of any future management strategy. Many catchments have greatly reduced infiltration rates and buffering capacity and this process needs to be reversed. An interventionist and holistic approach to managing water quantity and quality at the catchment scale is urgently required through the active manipulation of natural flow processes. Both quantitative (field experiments and modelling) and qualitative evidence (local knowledge) is required to demonstrate that catchment have become 'unhealthy'. For example, dense networks of low cost instrumentation could provide this multiscale evidence and, coupled with stakeholder knowledge, build a comprehensive understanding of whole system function. Proactive Catchment System Management is an interventionist approach to altering the catchment scale runoff regime through the manipulation of landscape scale hydrological flow pathways. Many of the changes to hydrological processes cannot be detected at the catchment scale as the primary causes of flooding and pollution. Evidence shows it is the land cover and the soil that are paramount to any change. Local evidence shows us that intense agricultural practices reduce the infiltration capacity through soil degradation. The intrinsic buffering capacity has also been lost across the landscape. The emerging hydrological process is one in which the whole system responds too quickly (driven by near surface and overland flow processes). The bulk of the soil matrix is bypassed during storm events and there is little or no buffering capacity in the riparian areas or in headwater catchments. The prospect of lower intensity farming rates is

  4. Long-term, high-frequency water quality monitoring in an agricultural catchment: insights from spectral analysis

    NASA Astrophysics Data System (ADS)

    Aubert, Alice; Kirchner, James; Faucheux, Mikael; Merot, Philippe; Gascuel-Odoux, Chantal

    2013-04-01

    The choice of sampling frequency is a key issue in the design and operation of environmental observatories. The choice of sampling frequency creates a spectral window (or temporal filter) that highlights some timescales and processes, and de-emphasizes others (1). New online measurement technologies can monitor surface water quality almost continuously, allowing the creation of very rich time series. The question of how best to analyze such detailed temporal datasets is an important issue in environmental monitoring. In the present work, we studied water quality data from the AgrHys long-term hydrological observatory (located at Kervidy-Naizin, Western France) sampled at daily and 20-minute time scales. Manual sampling has provided 12 years of daily measurements of nitrate, dissolved organic carbon (DOC), chloride and sulfate (2), and 3 years of daily measurements of about 30 other solutes. In addition, a UV-spectrometry probe (Spectrolyser) provides one year of 20-minute measurements for nitrate and DOC. Spectral analysis of the daily water quality time series reveals that our intensively farmed catchment exhibits universal 1/f scaling (power spectrum slope of -1) for a large number of solutes, confirming and extending the earlier discovery of universal 1/f scaling in the relatively pristine Plynlimon catchment (3). 1/f time series confound conventional methods for assessing the statistical significance of trends. Indeed, conventional methods assume that there is a clear separation of scales between the signal (the trend line) and the noise (the scatter around the line). This is not true for 1/f noise, since it overestimates the occurrence of significant trends. Our results raise the possibility that 1/f scaling is widespread in water quality time series, thus posing fundamental challenges to water quality trend analysis. Power spectra of the 20-minute nitrate and DOC time series show 1/f scaling at frequencies below 1/day, consistent with the longer-term daily

  5. Identifying sediment sources in a drained lowland agricultural catchment: the application of a novel thorium-based particle size correction in sediment fingerprinting

    NASA Astrophysics Data System (ADS)

    Laceby, J. P.; Le Gall, M.; Foucher, A.; Salvador-Blanes, S.; Evrard, O.; Lefèvre, I.; Cerdan, O.; Desmet, M.

    2015-12-01

    Soil erosion is one of the main processes influencing land and water degradation at the global scale. Identifying the main sediment sources is therefore essential for effective soil erosion management. Accordingly, caesium-137 (137Cs) concentrations were used to quantify the relative contribution of surface and subsurface erosion sources in a lowland drained catchment in France. As 137Cs concentrations are often dependent on particle size, specific surface area (SSA) and novel Thorium (Th) based particle size corrections were applied. Surface and subsurface samples were collected to characterize the radionuclide properties of potential sources. Sediment samples were collected during one hydrological year and a sediment core was sampled to represent sediment accumulated over a longer temporal period. Additionally, sediment from tile drains was sampled to determine the radionuclide properties of sediment exported from the drainage network. The results highlight a substantial enrichment in fine particles and associated 137Cs concentrations between the sources and the sediment. The application of both correction factors reduced this difference, with the Th correction providing a more accurate comparison of source and sediment samples than the SSA correction. Modelling results clearly indicate the dominance of surface sources during the flood events and in the sediment core. Sediment exported from the drainage network was modelled to originate predominantly from surface sources. This study demonstrates the potential of Th to correct for 137Cs particle size enrichment. More importantly, this research indicates that drainage networks may significantly increase the connectivity of surface sources to stream networks. Managing sediment transferred through drainage networks may reduce the deleterious effects of suspended sediment loads on riverine systems in similar lowland drained agricultural catchments.

  6. Quantifying the dominant sources of sediment in a drained lowland agricultural catchment: The application of a thorium-based particle size correction in sediment fingerprinting

    NASA Astrophysics Data System (ADS)

    Foucher, Anthony; Laceby, Patrick J.; Salvador-Blanes, Sébastien; Evrard, Olivier; Le Gall, Marion; Lefèvre, Irène; Cerdan, Olivier; Rajkumar, Vignesh; Desmet, Marc

    2015-12-01

    suspended sediment loads on riverine systems in similar lowland drained agricultural catchments.

  7. Effects of harvest on carbon and nitrogen dynamics in a Pacific Northwest forest catchment

    EPA Science Inventory

    We used a new ecohydrological model, Visualizing Ecosystems for Land Management Assessments (VELMA), to analyze the effects of forest harvest on catchment carbon and nitrogen dynamics. We applied the model to a 10 ha headwater catchment in the western Oregon Cascade Range where t...

  8. A long-term data set for hydrologic modeling in a snow-dominated mountain catchment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An hourly modeling data set is presented for the water years 1984 through 2008 for a snow-dominated headwater catchment. Meteorological forcing data and GIS watershed characteristics are described and provided. The meteorological data are measured at two sites within the catchment, and include pre...

  9. The impact of cattle access on ecological water quality in streams: Examples from agricultural catchments within Ireland.

    PubMed

    Conroy, E; Turner, J N; Rymszewicz, A; O'Sullivan, J J; Bruen, M; Lawler, D; Lally, H; Kelly-Quinn, M

    2016-03-15

    Unrestricted cattle access to rivers and streams represent a potentially significant localised pressure on freshwater systems. However there is no consensus in the literature on the occurrence and extent of impact and limited research has examined the effects on aquatic biota in the humid temperate environment examined in the present study. Furthermore, this is one of the first times that research consider the potential for cattle access impacts in streams of varying water quality in Northern Europe. We investigated the effects of cattle access on macroinvertebrate communities and deposited fine sediment levels, in four rivers of high/good and four rivers of moderate water quality status which drain, low gradient, calcareous grassland catchments in Ireland. We assessed the temporal variability in macroinvertebrates communities across two seasons, spring and autumn. Site specific impacts were evident which appeared to be influenced by water quality status and season. All four high/good water status rivers revealed significant downstream changes in community structure and at least two univariate metrics (total richness and EPT richness together with taxon, E and EPT abundance). Two of the four moderate water status rivers showed significant changes in community structure, abundance and richness metrics and functional feeding groups driven in the main by downstream increases in collectors/gatherers, shredders and burrowing taxa. These two moderate water status rivers had high or prolonged livestock activity. In view of these findings, the potential for some of these sites to achieve at least high/good water quality status, as set out in the EU Water Framework Directive, may be compromised. The results presented highlight the need for additional research to further define the site specific factors and livestock management practices, under different discharge conditions, that increase the risk of impact on aquatic ecology due to these cattle-river interactions.

  10. Preferential flow and mixing process in the chemical recharge in subsurface catchments: observations and modeling

    NASA Astrophysics Data System (ADS)

    Gascuel-Odoux, C.; Rouxel, M.; Molenat, J.; Ruiz, L.; Aquilina, L.; Faucheux, M.; Labasque, T.; Sebilo, M.

    2012-04-01

    Shallow groundwater that develops on hillslopes is the main compartment in headwater catchments for flow and solute transport to rivers. Although spatial and temporal variations in its chemical composition are reported in the literature, there is no coherent description of the way these variations are organized, nor is there an accepted conceptual model for the recharge mechanisms and flows in the groundwater involved. We instrumented an intensive farming and subsurface dominant catchment located in Oceanic Western Europe (Kerbernez, Brittany, France), a headwater catchment included in the Observatory for Research on Environment AgrHyS (Agro-Hydro-System) and a part of the French Network of catchments for environmental research (SOERE RBV focused on the Critical Zone). These systems are strongly constrained by anthropogenic pressures (agriculture) and are characterized by a clear non-equilibrium status. A network of 42 nested piezometers was installed along a 200 m hillslope allowing water sampling along two transects in the permanent water table as well as in what we call the "fluctuating zone", characterized by seasonal alternance of saturated and unsaturated conditions. Water composition was monitored at high frequency (weekly) over a 3-year period for major anion composition and over a one year period for detailed 15N, CFC, SF6 and other dissolved gases. The results demonstrated that (i) the anionic composition in water table fluctuation zone varied significantly compared to deeper portions of the aquifer on the hillslope, confirming that this layer constitutes a main compartment for the mixing of new recharge water and old groundwater, (ii) seasonally, the variations of 15N and CFC are much higher during the recharge period than during the recession period, confirming the preferential flow during early recharge events, iii) variations of nitrate 15N and O18 composition was suggesting any significant denitrification process in the fluctuating zone, confirming

  11. Integrated modeling of agricultural scenarios (IMAS) to support pesticide action plans: the case of the Coulonge drinking water catchment area (SW France).

    PubMed

    Vernier, Françoise; Leccia-Phelpin, Odile; Lescot, Jean-Marie; Minette, Sébastien; Miralles, André; Barberis, Delphine; Scordia, Charlotte; Kuentz-Simonet, Vanessa; Tonneau, Jean-Philippe

    2017-03-01

    Non-point source pollution is a cause of major concern within the European Union. This is reflected in increasing public and political focus on a more sustainable use of pesticides, as well as a reduction in diffuse pollution. Climate change will likely to lead to an even more intensive use of pesticides in the future, affecting agriculture in many ways. At the same time, the Water Framework Directive (WFD) and associated EU policies called for a "good" ecological and chemical status to be achieved for water bodies by the end of 2015, currently delayed to 2021-2027 due to a lack of efficiency in policies and timescale of resilience for hydrosystems, especially groundwater systems. Water managers need appropriate and user-friendly tools to design agro-environmental policies. These tools should help them to evaluate the potential impacts of mitigation measures on water resources, more clearly define protected areas, and more efficiently distribute financial incentives to farmers who agree to implement alternative practices. At present, a number of reports point out that water managers do not use appropriate information from monitoring or models to make decisions and set environmental action plans. In this paper, we propose an integrated and collaborative approach to analyzing changes in land use, farming systems, and practices and to assess their effects on agricultural pressure and pesticide transfers to waters. The integrated modeling of agricultural scenario (IMAS) framework draws on a range of data and expert knowledge available within areas where a pesticide action plan can be defined to restore the water quality, French "Grenelle law" catchment areas, French Water Development and Management Plan areas, etc. A so-called "reference scenario" represents the actual soil occupation and pesticide-spraying practices used in both conventional and organic farming. A number of alternative scenarios are then defined in cooperation with stakeholders, including socio

  12. Environmental Risk Assessment of Fluctuating Diazinon Concentrations in an Urban and Agricultural Catchment Using Toxicokinetic–Toxicodynamic Modeling

    PubMed Central

    2011-01-01

    Temporally resolved environmental risk assessment of fluctuating concentrations of micropollutants is presented. We separated the prediction of toxicity over time from the extrapolation from one to many species and from acute to sublethal effects. A toxicokinetic–toxicodynamic (TKTD) model predicted toxicity caused by fluctuating concentrations of diazinon, measured by time-resolved sampling over 108 days from three locations in a stream network, representing urban, agricultural and mixed land use. We calculated extrapolation factors to quantify variation in toxicity among species and effect types based on available toxicity data, while correcting for different test durations with the TKTD model. Sampling from the distribution of extrapolation factors and prediction of time-resolved toxicity with the TKTD model facilitated subsequent calculation of the risk of undesired toxic events. Approximately one-fifth of aquatic organisms were at risk and fluctuating concentrations were more toxic than their averages. Contribution of urban and agricultural sources of diazinon to the overall risk varied. Thus using fixed concentrations as water quality criteria appears overly simplistic because it ignores the temporal dimension of toxicity. However, the improved prediction of toxicity for fluctuating concentrations may be small compared to uncertainty due to limited diversity of toxicity data to base the extrapolation factors on. PMID:21958042

  13. What do we know about past changes in the water cycle of Central Asian headwaters? A review

    NASA Astrophysics Data System (ADS)

    Unger-Shayesteh, Katy; Vorogushyn, Sergiy; Farinotti, Daniel; Gafurov, Abror; Duethmann, Doris; Mandychev, Alexander; Merz, Bruno

    2013-11-01

    We have reviewed about 100 studies on past changes in climate, snow cover, glaciers and runoff in Central Asian headwater catchments, which have been published in the past 20 years. We included studies published by Central Asian researchers in Russian language, which are usually not easily accessible to international researchers.

  14. Role of river bank erosion in sediment budgets of catchments within the Loire river basin (France)

    NASA Astrophysics Data System (ADS)

    Gay, Aurore; Cerdan, Olivier; Poisvert, Cecile; Landemaine, Valentin

    2014-05-01

    Quantifying volumes of sediments produced on hillslopes or in channels and transported or stored within river systems is necessary to establish sediment budgets. If research efforts on hillslope erosion processes have led to a relatively good understanding and quantification of local sources, in-channel processes remain poorly understood and quasi inexistent in global budgets. However, profound landuse changes and agricultural practices have altered river functioning, caused river bank instability and stream incision. During the past decades in France, river channelization has been perfomed extensively to allow for new agricultural practices to take place. Starting from a recent study on the quantification of sediment fluxes for catchments within the Loire river basin (Gay et al. 2013), our aim is to complete sediment budgets by taking into account various sources and sinks both on hillslope and within channel. The emphasis of this study is on river bank erosion and how bank erosion contributes to global budgets. A model of bank retreat is developed for the entire Loire river basin. In general, our results show that bank retreat is on average quite low with approximately 1 cm.yr-1. However, a strong variability exists within the study area with channels displaying values of bank retreat up to ~10 cm.yr-1. Our results corroborate those found by Landemaine et al. in 2013 on a small agricultural catchment. From this first step, quantification of volumes of sediment eroded from banks and available for transport should be calculated and integrated in sediment budgets to allow for a better understanding of basin functioning. Gay A., Cerdan O., Delmas M., Desmet M., Variability of sediment yields in the Loire river basin (France): the role of small scale catchments (under review). Landemaine V., Gay A., Cerdan O., Salvador-Blanes S., Rodriguez S. Recent morphological evolution of a headwater stream in agricultural context after channelization in the Ligoire river (France

  15. Agriculture

    EPA Pesticide Factsheets

    The EPA Agriculture Resource Directory offers comprehensive, easy-to-understand information about environmental stewardship on farms and ranches; commonsense, flexible approaches that are both environmentally protective and agriculturally sound.

  16. From Soil to Surface Water: a Meta-Analysis of Catchment-Scale Organic Matter Production and Transport

    NASA Astrophysics Data System (ADS)

    Gabor, R. S.; Brooks, P. D.; Perdrial, J. N.

    2015-12-01

    Organic matter plays a fundamental role in the ecology and biogeochemistry of many ecosystems, from soils to headwater streams to oceans. In most catchments, the terrestrial environment is the dominant source of organic matter for the aquatic system, and thus DOM represents a fundamental linkage between soil and surface water. With trends of increasing DOC concentrations observed in many areas of the world, there is growing interest in identifying which factors drive DOM concentration and chemistry. Studies of systems ranging from tropical rainforests to boreal landscapes have identified many catchment characteristics that co-vary with DOM concentration and chemistry. These include climate elements such as solar radiation and precipitation patterns, chemical measurements such as sulfate or chloride concentration, and land use impacts such as percent agriculture. The question of which catchment characteristics actually control DOM can be broken down into two parts: which factors control the production of mobile DOM and what drives DOM transport from the terrestrial to the aquatic system. Here we review studies covering a range of ecosystems, scales, and measurement techniques, to categorize the major state factors that drive catchment controls of aquatic organic matter. Specifically, we identify three major transport vectors that vary both in their timing of DOM transport to surface water and the propensity for DOM originating from terrestrial source areas to be modified during transport. We use this three vector conceptual model of transport to group catchments and identify reproducible signatures of DOM export with varying levels of disturbance. By developing a generalized conceptual model of catchment-scale controls on aquatic organic matter, we can predict how dissolved organic matter will respond to environmental change. This knowledge can then help guide best management practices.

  17. Insights in nutrient sources and transport from high-frequency monitoring at the outlet pumping station of an agricultural lowland polder catchment

    NASA Astrophysics Data System (ADS)

    Rozemeijer, J.; Van der Grift, B.; Broers, H. P.; Berendrecht, W.; Oste, L.; Griffioen, J.

    2015-12-01

    In this study, we present new insights in nutrient sources and transport processes in an agricultural-dominated lowland water system based on high-frequency monitoring technology. Starting in October 2014, we have collected semi-continuous measurements of the TP and NO3 concentrations, conductivity and water temperature at a large scale pumping station at the outlet of a 576 km2 polder catchment. The semi-continuous measurements complement a water quality monitoring program at six locations within the drainage area based on conventional monthly or biweekly grab sampling. The NO3 and TP concentrations at the pumping station varied between 0.5 and 10 mgN/L and 0.1 and 0.5 mgP/L. The seasonal trends and short scale concentration dynamics clearly indicated that most of the NO3 loads at the pumping station originated from subsurface drain tubes that were active after intensive rainfall events during the winter months. A transfer function-noise model of hourly NO3 concentrations reveals that a large part of the dynamics in NO3 concentrations during the winter months can be predicted using rainfall data. In February however, NO3 concentrations were higher than predicted due to direct losses after the first manure application. The TP concentration almost doubled during operation of the pumping station. This highlights resuspension of particulate P from channel bed sediments induced by the higher flow velocities during pumping. Rainfall events that caused peaks in NO3 concentrations did not result in TP concentration peaks. Direct effects of run-off, with an association increase in the TP concentration and decrease of the NO3concentration, was only observed during rainfall event at the end of a freeze-thaw cycle. The high-frequency monitoring at the outlet of an agricultural-dominated lowland water system in combination with low-frequency monitoring within the area provided insight in nutrient sources and transport processes that are highly relevant for water quality

  18. The use of GIS and multi-criteria evaluation (MCE) to identify agricultural land management practices which cause surface water pollution in drinking water supply catchments.

    PubMed

    Grayson, Richard; Kay, Paul; Foulger, Miles

    2008-01-01

    Diffuse pollution poses a threat to water quality and results in the need for treatment for potable water supplies which can prove costly. Within the Yorkshire region, UK, nitrates, pesticides and water colour present particular treatment problems. Catchment management techniques offer an alternative to 'end of pipe' solutions and allow resources to be targeted to the most polluting areas. This project has attempted to identify such areas using GIS based modelling approaches in catchments where water quality data were available. As no model exists to predict water colour a model was created using an MCE method which is capable of predicting colour concentrations at the catchment scale. CatchIS was used to predict pesticide and nitrate N concentrations and was found to be generally capable of reliably predicting nitrate N loads at the catchment scale. The pesticides results did not match the historic data possibly due to problems with the historic pesticide data and temporal and spatially variability in pesticide usage. The use of these models can be extended to predict water quality problems in catchments where water quality data are unavailable and highlight areas of concern.

  19. Investigating the impact of data uncertainty on the estimation of catchment nutrient fluxes.

    NASA Astrophysics Data System (ADS)

    Lloyd, Charlotte; Freer, Jim; Collins, Adrian; Johnes, Penny; Coxon, Gemma

    2014-05-01

    Changing climate and a growing population are increasing pressures on the world's water bodies. Maintaining food security has resulted in changes in agricultural practices, leading to adverse impacts on water quality. To address this problem robust evidence is needed to determine which on-farm mitigation strategies are likely to be most effective in reducing pollutant impacts. The introduction of in-situ quasi-continuous monitoring of water quality provides the means to improve the characterisation of pollutant behaviour and gain new and more robust understanding of hydrological and biogeochemical flux behaviours in catchments. Here we analyse a suite of high temporal resolution data sets generated from in-situ sensor networks within an uncertainty framework to provide robust estimates of nutrient fluxes from catchments impacted by intensive agricultural production practices. Previous research into nutrient flux estimation has focused on assessing the uncertainty associated with the use of different load models to interpolate or extrapolate nutrient data where daily or sub-daily discharge data are generally available and used with lower resolution nutrient concentrations. In such studies examples of datasets where paired discharge and nutrient concentrations are available are used as a benchmark of 'truth' against which the other data models or sample resolutions are tested. This work illustrates that even given high temporal-resolution paired datasets, where no load model is necessary, there will still be significant uncertainties and therefore demonstrates the importance of analysing such data within an uncertainty framework to obtain robust estimates of catchment nutrient loads. This study uses 15-minute resolution paired velocity and stage height data, in order to calculate river discharge, along with high temporal resolution (15 or 30 minute) nutrient data from four field sites collected as part of the Hampshire Avon Demonstration Test Catchment project

  20. Headwater Streams in Porous Landscapes - What's the contributing area?

    NASA Astrophysics Data System (ADS)

    Jackson, C. R.; Bitew, M. M.; Du, E.; Griffiths, N.; Hopp, L.; Klaus, J.; McDonnell, J.; Vache, K. B.

    2015-12-01

    Building on a long legacy of hydrogeological investigations at the Savannah River Site in the Sandhills of the Upper Coastal Plain in South Carolina, we began in 2005 a headwater-scale investigation of hillslope flow pathways, streamflow sources, and water quality responses to intensive woody biomass production. The landscape is characterized by blackwater streams flowing slowly through wide flat stream valleys, deep unconsolidated layers of sands and clays, a regional clay layer beneath Fourmile Creek that defines the lower boundary of the surficial aquifer, rolling topography with steeper slopes on the valley margins and gentle slopes elsewhere, and a sandy clay loam argillic layer within 0.2 to 1.5m from the surface. Most water leaves headwater basins by groundwater flow, appearing as streamflow far downstream. Only at scales larger than 50 km2 does average streamflow match expectations from water balances. This raises the question, what constitutes the contributing area for headwater streams in porous landscapes? Perching and interflow generation over the argillic horizon is common, but leakage through clay is rapid relative to interflow travel times, so interflow serves to shift the point of percolation downslope from the point of infiltration. Only interflow from the valley-adjacent slopes can contribute to stormflow responses. Our interflow interception trenches and maximum rise piezometer networks reveal high heterogeneity in subsurface flow paths at multiple spatial scales. Streamwater has isotopic and chemical characteristics similar to deep groundwater, but we cannot easily determine the source area for groundwater reaching the first order streams. Our observations suggest that one's view of hillslope and catchment flow processes depends on the scale, number, and frequency of observations of state variables and outputs. In some cases, less frequent or less numerous observations of fewer tracers would have yielded different inferences. The data also

  1. Controls on scaling relationships of dynamic headwater stream networks

    NASA Astrophysics Data System (ADS)

    Godsey, S.; Kirchner, J. W.; Whiting, J. A.

    2013-12-01

    Stream networks expand and contract within their channel network, particularly within their headwaters. Along their length, especially during drought periods, it is not unusual to encounter dry reaches of varying lengths. Controls on the length and location of those dry reaches include: large woody debris, upstream sediment loading, hydraulic properties of the subsurface/hyporheic zone, and the catchment hydroclimate and morphology. Here we examine patterns in the length of discontinuous reaches, their location, and the length of the overall drainage network. We find that drainage networks expand with discharge as a power-law relationship with a slope of ~0.25, contradicting recent theoretical suggestions in the literature that this scaling exponent should be close to 1.0. We discuss physical limitations on the range of potential scaling relationships, and link stream responses to groundwater and evapotranspiration sources and sinks.

  2. Comprehensive multiyear carbon budget of a temperate headwater stream

    NASA Astrophysics Data System (ADS)

    Argerich, Alba; Haggerty, Roy; Johnson, Sherri L.; Wondzell, Steven M.; Dosch, Nicholas; Corson-Rikert, Hayley; Ashkenas, Linda R.; Pennington, Robert; Thomas, Christoph K.

    2016-05-01

    Headwater streams comprise nearly 90% of the total length of perennial channels in global catchments. They mineralize organic carbon entering from terrestrial systems, evade terrestrial carbon dioxide (CO2), and generate and remove carbon through in-stream primary production and respiration. Despite their importance, headwater streams are often neglected in global carbon budgets primarily because of a lack of available data. We measured these processes, in detail, over a 10 year period in a stream draining a 96 ha forested watershed in western Oregon, USA. This stream, which represents only 0.4% of the watershed area, exported 159 kg C ha-1 yr-1, similar to the global exports for large rivers. Stream export was dominated by downstream transport of dissolved inorganic carbon (63 kg C ha-1 yr-1) and by evasion of CO2 to the atmosphere (42 kg C ha-1 yr-1), leaving the remainder of 51 kg C ha-1 yr-1 for downstream transport of organic carbon (17 kg C ha-1 yr-1 and 34 kg C ha-1 yr-1 in dissolved and particulate form, respectively).

  3. Contribution of a Headwater Stream to the Global Carbon Budget

    NASA Astrophysics Data System (ADS)

    Argerich, A.; Johnson, S. L.; Haggerty, R.; Dosch, N.; Corson-Rikert, H.; Ashkenas, L.; Pennington, R.; Wondzell, S. M.

    2014-12-01

    The carbon cycle has been subject of numerous studies in recent years, primarily due to the role of CO2 and CH4 in global warming. Understanding the components and processes contributing to the global carbon cycle across a landscape is essential to understand climate change drivers and predicting future climate. Although the role of streams and rivers in transporting and processing nutrients from the land to the ocean has been widely recognized, most climate models still consider riverine systems as mere conduits without processing capacity. Evasion of carbon dioxide from inland waters has only been recently acknowledged to be an important source of carbon to the atmosphere and still, these estimations don't take into account evasion from headwater streams due to a lack of data. Here we present a 10-year C budget for a small headwater stream draining a 96-ha watershed in western Oregon, USA. This stream exported ~5000 g C per m2 of stream area, approximately 9% of the ecosystem production of the catchment (NEP). Export is dominated by evasion of CO2 to the atmosphere (~2200 g C per m2/y) and by downstream transport of dissolved inorganic carbon (DIC, ~1300 g per m2/y). Although highest in-stream pCO2 and DIC concentrations happen during summer low-flows, most stream export happens during winter high flows indicating at least a seasonal lag between CO2 production (i.e., respiration) and carbon export.

  4. Comparative analyses of factors determining soil erosion rates based on network of Mediterranean monitored catchments for the innovative, adaptive and resilient agriculture of the future

    NASA Astrophysics Data System (ADS)

    Smetanová, Anna; Le Bissonnais, Yves; Raclot, Damien; Perdo Nunes, João; Licciardello, Feliciana; Mathys, Nicolle; Latron, Jérôme; Rodríguez Caballero, Emilio; Le Bouteiller, Caroline; Klotz, Sébastien; Mekki, Insaf; Gallart, Francesc; Solé Benet, Albert; Pérez Gallego, Nuria; Andrieux, Patrick; Jantzi, Hugo; Moussa, Roger; Planchon, Olivier; Marisa Santos, Juliana

    2015-04-01

    In order to project the soil erosion response to climate change in the fragile Mediterranean region it is inevitable to understand its existing patterns. Soil erosion monitoring on a catchment scale enables to analyse temporal and spatial variability of soil erosion and sediment delivery, while the integrating study of different catchments is often undertaken to depicther the general patterns. In this study, eight small catchments (with area up to 1,32 km2), representative for the western part of the Mediterranean region (according to climate, bedrock, soils and main type of land use) were compared. These catchments, grouped in the R-OS Med Network were situated in France (3), Spain (2), Portugal (1), Italy (1) and Tunisia (1). The average precipitation ranged between 236 to 1303 mm·a-1 and mean annual sediment yield varied 7.5 to 6900 Mg·km-2·a-1. The complex databes was based on more than 120 years of hydrological and sediment data, with series between 3 and 29 years long. The variability of sediment data was described on annual and monthly basis. The relationship between the sediment yield and more than 35 factors influencing the sediment yield including the characteristics of climate, topography, rainfall, runoff, land use, vegetation and soil cover, connectivity and dominant geomorphic processes, was studied. The preliminary results confirmed the differences in rainfall, runoff and sediment response, and revealed both the similarities and differences in soil erosion responses of the catchments. They are further dependent on the variability of factors themselves, with important contribution of the state of soil properties, vegetation cover and land use. Anna Smetanová has received the support of the European Union, in the framework of the Marie-Curie FP7 COFUND People Programme, through the award of an AgreenSkills' fellowship (under grant agreement n° 267196)

  5. Water and chemical recharge in subsurface catchment: observations and consequences for modeling

    NASA Astrophysics Data System (ADS)

    Gascuel-odoux, C.; Aquilina, L.; Faucheux, M.; Merot, P.; Molenat, J.; de Monteti, V.; Sebilo, M.; Rouxel, M.; Ruiz, L.

    2011-12-01

    Shallow groundwater that develops on hillslopes is the main compartment in headwater catchments for flow and solute transport to rivers. Although spatial and temporal variations in its chemical composition are reported in the literature, there is no coherent description of the way these variations are organized, nor is there an accepted conceptual model for the recharge mechanisms and flows in the groundwater involved. We instrumented an intensive farming and subsurface dominant catchment located in Oceanic Western Europe (France), included in AgrHyS catchments (for Agro-Hydro-SyStem) and a part of the French network of catchments for environmental research (SOERE RBV dedicated to the Critical Zone). It is strongly constrained by anthropogenic pressures (agriculture) and is characterized by a clear non-equilibrium status. A network of 42 nested piezometers was installed along a 200 m hillslope allowing water sampling in the permanent water table as well as in what we call the fluctuating zone, characterized by seasonal alternance of saturated and unsaturated conditions. Water composition was monitored at high frequency (weekly) over a 3-year period for major anion composition and over a one year period for detailed 15N, CFC, SF6 and other dissolved gases composition. The results demonstrated that (i) the anionic composition in water table fluctuation zone varied significantly compared to deeper portions of the aquifer on the hillslope, confirming that this layer constitutes a main compartment for the mixing of new recharge water and old groundwater, (ii) seasonally, the variations of 15N and CFC are much higher during the recharge period than during the recession period, confirming the preferential flow during early recharge events, iii) variations of nitrate 15N and O18 composition was suggesting any significant denitrification process in the fluctuating zone, confirming the dominance of the mixing processes in the fluctuating zone, iv) deeper parts of the aquifer

  6. A 25-year Simulation of Snow Deposition and Melt over a Semiarid Mountain Catchment

    NASA Astrophysics Data System (ADS)

    Marks, D. G.; Reba, M. L.; Winstral, A. H.; Kumar, M.

    2009-12-01

    Both urban and agricultural systems in the mountains of the western US are water limited, and nearly all water in the region comes from melting snow. Over the last 20-30 years climate warming in western North America has resulted in a critical shift in patterns of snow deposition and melt. A carefully collected, processed, and validated meteorological dataset for the 1984 - 2008 water years was assembled for a headwater catchment within the Reynolds Creek Experimental Watershed in the Owyhee Mountains of Idaho. These data are used to force the Isnobal energy balance snow model to simulate patterns of snow deposition and melt over the catchment for the 25-year period. The simulation period includes both the highest (1984) and lowest (1992) snow seasons, along with a high degree of inter-annual variability. Results indicate statistically significant trend toward more rain and less snow, earlier melt, and reduced summer streamflow. In this region nearly all precipitation occurs during winter and spring, with very dry summer and fall seasons. Earlier melt and more winter rain will negatively impact growing season water supplies in the region even if precipitation is unchanged.

  7. Influence of instream habitat and water quality on aggressive behavior in crayfish of channelized headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many agricultural drainage ditches that border farm fields of the Midwestern United States are degraded headwater streams that possess communities of crayfish. We hypothesized that crayfish communities at sites with low instream habitat diversity and poor water quality would show greater evidence of...

  8. Characterization of major-ion chemistry and nutrients in headwater streams along the Appalachian National Scenic Trail and within adjacent watersheds, Maine to Georgia

    USGS Publications Warehouse

    Argue, Denise M.; Pope, Jason P.; Dieffenbach, Fred

    2012-01-01

    An inventory of water-quality data on field parameters, major ions, and nutrients provided a summary of water quality in headwater (first- and second-order) streams within watersheds along the Appalachian National Scenic Trail (Appalachian Trail). Data from 1,817 sampling sites in 831 catchments were used for the water-quality summary. Catchment delineations from NHDPlus were used as the fundamental geographic units for this project. Criteria used to evaluate sampling sites for inclusion were based on selected physical attributes of the catchments adjacent to the Appalachian Trail, including stream elevation, percentage of developed land cover, and percentage of agricultural land cover. The headwater streams of the Appalachian Trail are generally dilute waters, with low pH, low acid neutralizing capacity (ANC), and low concentrations of nutrients. The median pH value was slightly acidic at 6.7; the median specific conductance value was 23.6 microsiemens per centimeter, and the median ANC value was 98.7 milliequivalents per liter (μeq/L). Median concentrations of cations (calcium, magnesium, sodium, and potassium) were each less than 1.5 milligrams per liter (mg/L), and median concentrations of anions (bicarbonate, chloride, fluoride, sulfate, and nitrate) were less than 10 mg/L. Differences in water-quality constituent levels along the Appalachian Trail may be related to elevation, atmospheric deposition, geology, and land cover. Spatial variations were summarized by ecological sections (ecosections) developed by the U.S. Forest Service. Specific conductance, pH, ANC, and concentrations of major ions (calcium, chloride, magnesium, sodium, and sulfate) were all negatively correlated with elevation. The highest elevation ecosections (White Mountains, Blue Ridge Mountains, and Allegheny Mountains) had the lowest pH, ANC, and concentrations of major ions. The lowest elevation ecosections (Lower New England and Hudson Valley) generally had the highest pH, ANC, and

  9. High frequency variability of environmental drivers determining benthic community dynamics in headwater streams.

    PubMed

    Snell, M A; Barker, P A; Surridge, B W J; Large, A R G; Jonczyk, J; Benskin, C McW H; Reaney, S; Perks, M T; Owen, G J; Cleasby, W; Deasy, C; Burke, S; Haygarth, P M

    2014-07-01

    Headwater streams are an important feature of the landscape, with their diversity in structure and associated ecological function providing a potential natural buffer against downstream nutrient export. Phytobenthic communities, dominated in many headwaters by diatoms, must respond to physical and chemical parameters that can vary in magnitude within hours, whereas the ecological regeneration times are much longer. How diatom communities develop in the fluctuating, dynamic environments characteristic of headwaters is poorly understood. Deployment of near-continuous monitoring technology in sub-catchments of the River Eden, NW England, provides the opportunity for measurement of temporal variability in stream discharge and nutrient resource supply to benthic communities, as represented by monthly diatom samples collected over two years. Our data suggest that the diatom communities and the derived Trophic Diatom Index, best reflect stream discharge conditions over the preceding 18-21 days and Total Phosphorus concentrations over a wider antecedent window of 7-21 days. This is one of the first quantitative assessments of long-term diatom community development in response to continuously-measured stream nutrient concentration and discharge fluctuations. The data reveal the sensitivity of these headwater communities to mean conditions prior to sampling, with flow as the dominant variable. With sufficient understanding of the role of antecedent conditions, these methods can be used to inform interpretation of monitoring data, including those collected under the European Water Framework Directive and related mitigation efforts.

  10. In Lieu of the Paired-Catchment Approach - Hydrologic Model Change Detection at the Catchment Scale

    NASA Astrophysics Data System (ADS)

    Zegre, N. P.

    2009-05-01

    Knowledge of the effects of forest management on hydrology primarily comes from paired-catchment studies conducted world-wide. While this approach has been useful for discerning changes in small experimental catchments and has contributed fundamental knowledge of the effects of forest and natural resources management on hydrology, results from experimental catchment studies exhibit temporal variability, have limited spatial inference, and lack insight into internal catchment processes. To address these limitations, traditional field experiments can be supplemented with numerical models to isolate the effects of disturbance on catchment behavior. Outlined in this study is an alternative method of change detection for daily time-series streamflow that integrates hydrologic modeling and statistical change detection methods used to discern the effects of contemporary forest management on the hydrology of western Oregon Cascades headwater catchments. In this study, a simple rainfall-runoff model was used to generate virtual reference catchments using attributes that reflect streamflow conditions absent of forest disturbance. Streamflow was simulated under three levels of model uncertainty using GLUE and were used to construct generalized least squares regression models to discern changes in hydrologic behavior. By considering processes within a single experimental catchment rather than the two spatially explicit catchments used in traditional paired experiments, it was possible to reduce unexplained variation and increase the likelihood of correctly detecting hydrologic effects following forest harvesting. In order to evaluate the stability of the hydrologic and statistical models and catchment behavior over time, the change detection method was applied to a contemporary reference catchment. By applying the change detection model to reference catchments, it was possible to eliminate unexpected variation as a cause for detected changes in observed hydrology. Further, it

  11. Spatially intensive sampling by electrofishing for assessing longitudinal discontinuities in fish distribution in a headwater stream

    USGS Publications Warehouse

    Le Pichon, Céline; Tales, Évelyne; Belliard, Jérôme; Torgersen, Christian E.

    2017-01-01

    Spatially intensive sampling by electrofishing is proposed as a method for quantifying spatial variation in fish assemblages at multiple scales along extensive stream sections in headwater catchments. We used this method to sample fish species at 10-m2 points spaced every 20 m throughout 5 km of a headwater stream in France. The spatially intensive sampling design provided information at a spatial resolution and extent that enabled exploration of spatial heterogeneity in fish assemblage structure and aquatic habitat at multiple scales with empirical variograms and wavelet analysis. These analyses were effective for detecting scales of periodicity, trends, and discontinuities in the distribution of species in relation to tributary junctions and obstacles to fish movement. This approach to sampling riverine fishes may be useful in fisheries research and management for evaluating stream fish responses to natural and altered habitats and for identifying sites for potential restoration.

  12. Catchment hydrological responses to forest harvest amount and spatial pattern - 2011

    EPA Science Inventory

    We used an ecohydrological model, Visualizing Ecosystems for Land Management Assessments (VELMA), to analyze the effects of forest harvest location and amount on ecosystem carbon (C) and nitrogen (N) dynamics in an intensively studied headwater catchment (WS10) in western Oregon,...

  13. Catchment-scale biogeography of riverine bacterioplankton.

    PubMed

    Read, Daniel S; Gweon, Hyun S; Bowes, Michael J; Newbold, Lindsay K; Field, Dawn; Bailey, Mark J; Griffiths, Robert I

    2015-02-01

    Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physico-chemical status of the river.

  14. Catchment-scale biogeography of riverine bacterioplankton

    PubMed Central

    Read, Daniel S; Gweon, Hyun S; Bowes, Michael J; Newbold, Lindsay K; Field, Dawn; Bailey, Mark J; Griffiths, Robert I

    2015-01-01

    Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physico-chemical status of the river. PMID:25238398

  15. The role of historical agricultural terraces in geo-hydrological risk reduction: a case study from the Bisagno Stream Catchment (Genoa, Italy)

    NASA Astrophysics Data System (ADS)

    Faccini, Francesco; Giostrella, Paola; Paliaga, Guido; Piana, Pietro; Sacchini, Alessandro

    2016-04-01

    Terraces, traditionally sustained by dry stonewalls, occupy about thirty percent of the territory of Liguria. If constantly maintained, they effectively contribute to slow down the natural slope erosion. When no longer managed, terraces are recognized as one of the reasons for increased geomorphological risk along the slopes and, consequently, at the bottom of the valley. This study concerns the terraced landscapes of the Bisagno Stream catchment, internationally known for the recent and recurring floods which affected the city of Genoa. The Bisagno Stream catchment is an example of historical evolution of the territory both in terms of land use change and geo-hydrological risk. The catchment, whose highest point is Mount Candelozzo (1034 m), has a total area of 95 km2. In its terminal stretch the stream flows across the eastern part of Genoa city centre. It is a typical valley of the Genoa metropolitan area, with steep slopes and short times of concentration. Here the signs of the tragic floods which have affected the area since 1970 are still visible. The most recent and tragic geo-hydrological event in Liguria took place in the Bisagno Valley in October 2014. The study was carried out with a multi-temporal comparison of the terraced areas using aerial photographs and regional cartographic information. A further step will involve the analysis and classification of the terraces based on their maintenance condition and hydrogeological effectiveness, using some representative areas of the valley as cases study. The comparison between the distribution of terraces in the Bisagno valley and applied geomorphological cartography suggests the need of measures to reduce the risk according to a suitable set of priorities, including the recovery of the terraced areas and connected structures aimed to limit the accumulation of solid material along the main waterway.

  16. Effect of riparian vegetation on diatom assemblages in headwater streams under different land uses.

    PubMed

    Hlúbiková, Daša; Novais, Maria Helena; Dohet, Alain; Hoffmann, Lucien; Ector, Luc

    2014-03-15

    Differences in the structure of diatom assemblages in headwaters with contrasting shading conditions and different land use in the buffer zone and upper catchment were studied in order to evaluate the influence of the lack of riparian vegetation on the biofilm. The objective was to ascertain whether a riparian buffer can mitigate the negative influence of human induced disturbance and pollution on diatom assemblages in headwaters. Four streams were selected in order to maximize the differences in the land cover and minimize other environmental gradients. Multivariate statistics, different comparative and permutation tests and correlations were applied to compare the diatom assemblages, the Specific Polluosensitivity Index (IPS) and the diatom ecological guilds (low profile, high profile and motile) among the sites studied and to evaluate their responses to disturbances. The analysis showed that low profile diatoms typically dominated in forested headwaters with limited resources, whilst assemblages at impacted sites showed a wider range of growth forms. In unimpacted streams, the diatom assemblages were influenced by temperature, pH, conductivity and calcium, as usually reported for oligotrophic streams with high natural disturbance due to fast current and shading. In both shaded and unshaded impacted streams, the importance of nutrients and land use disturbance, especially urbanization, prevailed. This trend was also reflected by the IPS index that showed consistently lower values at impacted sites, correlating most significantly with nutrients. The diatom species composition as well as diatom guilds at impacted sites were similar, regardless of the presence or absence of riparian vegetation, and were significantly influenced by seasonal changes. Our results indicate that diatoms react sensitively to alterations of the water environment in headwaters, induced by anthropogenic activities, and these impacts are not buffered by an intact riparian zone. Diatoms

  17. Seasonal trends in stable water isotopes and estimation of mean transit times for mesoscale catchments with mixed landuse in northeastern Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Chutko, Krys; James, April; McConnell, Chris; Yao, Huaxia

    2015-04-01

    Northern Ontario Precambrian shield basins include considerable surface water (large lakes, wetlands), moderate relief (e.g. 400 m), variation in surficial geology (clay belt soils, glacial tills), and increasingly, the influence of human landuse impact (e.g. urban, agriculture) that are characteristic of northern Ontario, Quebec and parts of Scandinavia. In northeastern Ontario, Lake Nipissing and the French River are part of an important headwater tributary that flows into Georgian Bay, Lake Huron. Lake Nipissing and its 13,000 km2 watershed is the source of water to local municipalities and First Nation communities, home to a First Nations fishery and 5{%} of Ontario's recreational angling, and contributes an estimated 100 million/year to Ontario's economy. In 2012, in response to increasing concerns over water quality and its implications for ecological and economic systems, and limited study of water quality and quantity in the Sturgeon River-Lake Nipissing-French River (SNF) basin, we initiated a stable water isotope (SWI) study to examine how landscape characteristics influence streamflow generation at scales where both natural landscape variation (e.g. surface reservoirs, clay belt soils, forested headwaters) and anthropogenic stressors (urbanization, agriculture) are anticipated to influence water quantity and quality. Bi-weekly to monthly monitoring of SWI in precipitation and streamflow began in January 2013. Catchments range in size from 35 to 6,875 km^2, with a median size of 197 km2 and median gradients from 1 to 8{%}. Landcover includes considerable agricultural (0-18{%}) and/or urban (0-47{%}) area. Lakes and wetlands together cover 10-25{%} of catchment area, with large individual lakes (e.g. Lake Temagami) acting as important reservoir storage for hydropower generation. The existing SWI dataset includes 2 years of streamflow data for 5 of the larger catchments, > 1 year for an additional 2 catchments, and 2 years of seasonal ice-off data for the

  18. Characterizing hydrologic permanence in headwater streams

    EPA Science Inventory

    The presentation will be an overview of research to inform jurisdictional determinations for the Clean Water Act, in particular research that hydrographic comparisons of the extent and hydrologic permanence of headwater streams, indicator development, and an evaluation of a rapid...

  19. How tritium illuminates catchment structure

    NASA Astrophysics Data System (ADS)

    Stewart, M.; Morgenstern, U.; McDonnell, J.

    2012-04-01

    Streams contain water which has taken widely-varying times to pass through catchments, and the distribution of ages is likely to change with the flow. Part of the water has 'runoff' straight to the stream with little delay, other parts are more delayed and some has taken years (in some cases decades) to traverse the deeper regolith or bedrock of the catchment. This work aims to establish the significance of the last component, which is important because it can cause catchments to have long memories of contaminant inputs (e.g. nitrate). Results of tritium studies on streams world-wide were accessed from the scientific literature. Most of the studies assumed that there were just two age-components present in the streams (i.e. young and old). The mean ages and proportions of the components were found by fitting simulations to tritium data. It was found that the old component in streams was substantial (average was 50% of the annual runoff) and had considerable age (average mean age was 10 years) (Stewart et al., 2010). Use of oxygen-18 or chloride variations to estimate streamflow mean age usually does not reveal the age or size of this old component, because these methods cannot detect water older than about four years. Consequently, the use of tritium has shown that substantial parts of streamflow in headwater catchments are older than expected, and that deep groundwater plays an active and sometimes even a dominant role in runoff generation. Difficulties with interpretation of tritium in streams in recent years due to interference from tritium due to nuclear weapons testing are becoming less serious, because very accurate tritium measurements can be made and there is now little bomb-tritium remaining in the atmosphere. Mean ages can often be estimated from single tritium measurements in the Southern Hemisphere, because there was much less bomb-tritium in the atmosphere. This may also be possible for some locations in the Northern Hemisphere. Age determination on

  20. Land use control of nitrate export behavior across catchments

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Schmidt, Christian; Selle, Benny; Fleckenstein, Jan H.

    2014-05-01

    Nutrient exports from catchments and their temporal and spatial variability significantly affect downstream water quality and ecosystem health. There is hence a need to better understand and classify catchment nutrient export dynamics in order to reproduce catchment functions (such as nutrient mobilization and retention) and predict the response of these functions to changing boundary conditions. However, the complexity of catchment structure and the multitude of the processes involved challenge this objective. One approach to meet this challenge is a top-down, data-driven analysis of integrated catchment responses, such as discharge and solute concentration time series. For top-down analysis, different catchments are compared to identify key variables governing catchment response. We conducted a multi-catchment study applying top-down methods to analyze nitrate concentration and discharge time series from streams draining nine catchments in central Germany. The studied catchments, ranging from "pristine" mountains to agriculturally-managed lowlands, span gradients in land use, geology, and climatic conditions. We hypothesized that land use type is the main control on stream nitrate concentrations and catchment export behaviour, with more chemostatic export behaviour occurring in catchments with higher percentages of agricultural land use due to the presence of large nitrate stocks that effectively function as an unlimited nitrate storage. Consistent with this hypothesis we found that median nitrate concentrations were positively correlated with the percentage of agricultural land use in the different catchments despite differences in catchment climatic and geological conditions. Magnitude and direction of concentration-discharge relationship was evaluated using the slope b of the linear regression of log nitrate concentrations vs. log discharge as a metric for export behaviour. All catchments exhibited a positive slope b indicating concentrations increase with

  1. Shallow bedrock limits groundwater seepage-based headwater climate refugia

    USGS Publications Warehouse

    Briggs, Martin; Lane, John; Snyder, Craig D.; White, Eric A.; Johnson, Zachary; Nelms, David L.; Hitt, Nathaniel P.

    2017-01-01

    Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal and long-term air temperature dynamics. Depth to bedrock can directly influence shallow aquifer flow and thermal sensitivity, but is typically ill-defined along the stream corridor in steep mountain catchments. We employ rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting cold water-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park, VA, USA. Using a mean depth to bedrock of 2.6 m, numerical models predicted strong sensitivity of shallow aquifer temperature to the downward propagation of surface heat. The annual temperature dynamics (annual signal amplitude attenuation and phase shift) of potential seepage sourced from the shallow modeled aquifer were compared to several years of paired observed stream and air temperature records. Annual stream water temperature patterns were found to lag local air temperature by ∼8–19 d along the stream corridor, indicating that thermal exchange between the stream and shallow groundwater is spatially variable. Locations with greater annual signal phase lag were also associated with locally increased amplitude attenuation, further suggestion of year-round buffering of channel water temperature by groundwater seepage. Numerical models of shallow groundwater temperature that incorporate regional expected climate warming trends indicate that the summer cooling capacity of this groundwater seepage will be reduced over time, and lower-elevation stream sections may no longer serve as larger

  2. Suckers in headwater tributaries, Wyoming

    USGS Publications Warehouse

    Sweet, D.E.; Compton, R.I.; Hubert, W.A.

    2009-01-01

    Bluehead sucker (Catostomus discobolus) and flannelmouth sucker (Catostomus latipinnis) populations are declining throughout these species' native ranges in the Upper Colorado River Basin. In order to conserve these populations, an understanding of population dynamics is needed. Using age estimates from pectoral fin rays, we describe age and growth of these 2 species in 3 Wyoming stream systems: Muddy Creek, the Little Sandy River, and the Big Sandy River. Within all 3 stream systems, flannelmouth suckers were longer-lived than bluehead suckers, with maximum estimated ages of 16 years in Muddy Creek, 18 years in Little Sandy Creek, and 26 years in the Big Sandy River. Bluehead suckers had maximum estimated ages of 8 years in Muddy Creek, 10 years in Little Sandy Creek, and 18 years in the Big Sandy River. These maximum estimated ages were substantially greater than in other systems where scales have been used to estimate ages. Mean lengths at estimated ages were greater for flannelmouth suckers than for bluehead suckers in all 3 streams and generally less than values published from other systems where scales were used to estimate ages. Our observations of long life spans and slow growth rates among bluehead suckers and flannelmouth suckers were probably associated with our use of fin rays to estimate ages as well as the populations being in headwater tributaries near the northern edges of these species' ranges.

  3. The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 Streams and Catchments (Version 2.1) for the Conterminous United States: 2006 National Land Cover Database Agricultural Land Cover on Slopes

    EPA Pesticide Factsheets

    This dataset represents data derived from the NLCD dataset and the National Hydrography Dataset version 2.1(NHDPlusV2) (see Data Sources for links to NHDPlusV2 data and NLCD). Attributes were calculated for every local NHDPlusV2 catchment and accumulated to provide watershed-level metrics for agricultural classes (classes 81 and 82) within the NLCD on DEM-derived slopes >10% and >20%. This data set is derived from the NLCD raster composed of 16 land cover classes (categorical data type) for the conterminous USA. 2 classes were isolated to represent apricultural land cover. This raster was produced based on a decision-tree classification of circa 2006 Landsat satellite data.(see Data Structure and Attribute Information for a description of each metric). Included with NHDPlusV2 is the National Elevation Dataset (NED) which was used to create 2 slope rasters to find areas with slope >10% and >20%. These rasters were used as masks to locate areas where NLCD agricultural classes (classes 81 and 82) occur on slopes >10% and >20%.

  4. A catchment-scale method to simulating the impact of historical nitrate loading from agricultural land on the nitrate-concentration trends in the sandstone aquifers in the Eden Valley, UK.

    PubMed

    Wang, Lei; Burke, Sean P

    2017-02-01

    Nitrate water pollution, which is mainly caused by agricultural activities, remains an international problem. It can cause serious long-term environmental and human health issues due to nitrate time-lag in the groundwater system. However, the nitrate subsurface legacy issue has rarely been considered in environmental water management. We have developed a simple catchment-scale approach to investigate the impact of historical nitrate loading from agricultural land on the nitrate-concentration trends in sandstones, which represent major aquifers in the Eden Valley, UK. The model developed considers the spatio-temporal nitrate loading, low permeability superficial deposits, dual-porosity unsaturated zones, and nitrate dilution in aquifers. Monte Carlo simulations were undertaken to analyse parameter sensitivity and calibrate the model using observed datasets. Time series of annual average nitrate concentrations from 1925 to 2150 were generated for four aquifer zones in the study area. The results show that the nitrate concentrations in 'St Bees Sandstones', 'silicified Penrith Sandstones', and 'non-silicified Penrith Sandstones' keep rising or stay high before declining to stable levels, whilst that in 'interbedded Brockram Penrith Sandstones' will level off after a slight decrease. This study can help policymakers better understand local nitrate-legacy issues. It also provides a framework for informing the long-term impact and timescale of different scenarios introduced to deliver water-quality compliance. This model requires relatively modest parameterisation and is readily transferable to other areas.

  5. Blanket peatland restoration leads to reduced storm runoff from headwater systems

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Allott, Tim; Evans, Martin; Pilkington, Mike

    2016-04-01

    This paper presents data on the impact of largescale peatland restoration on catchment runoff from peatlands in northern England. The blanket peatlands of the Pennine hills are important sources of water supply and form the headwaters of major river systems. These peatlands are severely eroded with extensive gullying and bare peat resulting from the impacts of industrial pollution, overgrazing, wildfire and climatic change over the last millennium. In the last decade there has been a major programme of peatland restoration through re-vegetation and blocking of drainage lines in these systems. The Making Space for Water project has collected hydrological data from five micro-catchments(two restoration treatments, a bare peat control, a vegetated control and a previously restored site) over a four year period. This has allowed for both Before-After-Control-Intervention and Space for Time analysis of the impact of restoration on downstream runoff. Catchments became wetter following re-vegetation, water tables rose by 35 mm and overland flow production increased by 18%. Storm-flow lag times in restored catchments increased by up to 267 %, while peak storm discharge decreased by up to 37%. There were no statistically significant changes in percentage runoff, indicating limited changes to within-storm catchment storage. Natural flood management solutions are typically focussed around one of two main mechanisms, either enhanced storage of water in catchments or measures which slow transmission of water to channels and within channels. Upland peatlands are often mischaracterised as sponges and assumed to mitigate downstream runoff through additional storage. The results of this study suggest that whilst restoration of upland peatlands can lead to significant reductions in peak discharge, and has potential to contribute to natural flood risk management, the mechanism is an increase in catchment roughness and an associated decrease in flow velocities.

  6. Variability in isotopic composition of base flow in two headwater streams of the southern Appalachians

    NASA Astrophysics Data System (ADS)

    Singh, Nitin K.; Emanuel, Ryan E.; McGlynn, Brian L.

    2016-06-01

    We investigated the influence of hillslope scale topographic characteristics and the relative position of hillslopes along streams (i.e., internal catchment structure) on the isotopic composition of base flow in first-order, forested headwater streams at Coweeta Hydrologic Laboratory. The study focused on two adjacent forested catchments with different topographic characteristics. We used stable isotopes (18O and 2H) of water together with stream gauging and geospatial analysis to evaluate relationships between internal catchment structure and the spatiotemporal variability of base flow δ18O. Base flow δ18O was variable in space and time along streams, and the temporal variability of base flow δ18O declined with increasing drainage area. Base flow became enriched in 18O moving along streams from channel heads to catchment outlets but the frequency of enrichment varied between catchments. The spatiotemporal variability in base flow δ18O was high adjacent to large hillslopes with short flow paths, and it was positively correlated with the relative arrangement of hillslopes within the catchment. These results point to influence of unique arrangement of hillslopes on the patterns of downstream enrichment. Spatial variability in base flow δ18O within the streams was relatively low during dry and wet conditions, but it was higher during the transition period between dry and wet conditions. These results suggest that the strength of topographic control on the isotopic composition of base flow can vary with catchment wetness. This study highlights that topographic control on base flow generation and isotopic composition is important even at fine spatial scales.

  7. Instrumenting an upland research catchment in Canterbury, New Zealand to study controls on variability of soil moisture, shallow groundwater and streamflow

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary; Srinivasan, Ms

    2015-04-01

    Hydrologists recognise the importance of vertical drainage and deep flow paths in runoff generation, even in headwater catchments. Both soil and groundwater stores are highly variable over multiple scales, and the distribution of water has a strong control on flow rates and timing. In this study, we instrumented an upland headwater catchment in New Zealand to measure the temporal and spatial variation in unsaturated and saturated-zone responses. In NZ, upland catchments are the source of much of the water used in lowland agriculture, but the hydrology of such catchments and their role in water partitioning, storage and transport is poorly understood. The study area is the Langs Gully catchment in the North Branch of the Waipara River, Canterbury: this catchment was chosen to be representative of the foothills environment, with lightly managed dryland pasture and native Matagouri shrub vegetation cover. Over a period of 16 months we measured continuous soil moisture at 32 locations and near-surface water table (< 2 m) at 14 locations, as well as measuring flow at 3 stream gauges. The distributed measurement sites were located to allow comparisons between North and South facing locations, near-stream versus hillslope locations, and convergent versus divergent hillslopes. We found that temporal variability is strongly controlled by the climatic seasonal cycle, for both soil moisture and water table, and for both the mean and extremes of their distributions. Groundwater is a larger water storage component than soil moisture, and the difference increases with catchment wetness. The spatial standard deviation of both soil moisture and groundwater is larger in winter than in summer. It peaks during rainfall events due to partial saturation of the catchment, and also rises in spring as different locations dry out at different rates. The most important controls on spatial variability are aspect and distance from stream. South-facing and near-stream locations have higher

  8. ARE SALAMANDERS USEFUL INDICATORS OF HYDROLOGIC PERMANENCE IN HEADWATER STREAMS?

    EPA Science Inventory

    Regulatory agencies need appropriate indicators of stream permanence to aid in jurisdictional determinations for headwater streams. We evaluated salamanders as permanence indicators because they are often abundant in fishless headwaters. Salamander and habitat data were collect...

  9. A method of computing uncertain nitrogen and phosphorus loads in a small stream from an agricultural catchment using continuous monitoring data

    NASA Astrophysics Data System (ADS)

    Kulasova, A.; Smith, P. J.; Beven, K. J.; Blazkova, S. D.; Hlavacek, J.

    2012-08-01

    SummaryA method for computing loads of total phosphorus and nitrate from a small catchment in the Czech Republic has been presented, given continuous measurements of water levels, turbidity and an ion-specific NO3-sbnd N probe together with a limited number of discharge measurements and analyses of grab samples. Given the observed variability in the observations, log-log regressions are used to convert water levels to discharge and to derive continuous estimates of total phosphorus and nitrate. Integrations to estimate loads using predicted values of the true discharges and concentrations are then carried out by a Monte Carlo method to avoid strong assumptions of independence and distribution. Coefficients of variation for the estimated monthly loads range from 5% to 23% for TP and 12-36% for NO3-sbnd N. At the annual time scales, coefficients of variation are of the order of 5% for both TP and NO3-sbnd N. The variability in the estimated annual loads between the years was, however, significantly larger than the uncertainties estimated within each year.

  10. ASSESSING HEADWATER STREAMS: LINKING LANDSCAPES TO STREAM NETWORKS

    EPA Science Inventory

    Headwater streams represent a significant land-water boundary and drain 70-80% of the landscape. Headwater streams are vital components to drainage systems and are directly linked to our downstream rivers and lakes. However, alteration and loss of headwater streams have occurre...

  11. Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; effects of nutrient management on quality of surface runoff at a small carbonate-rock site near Ephrate, Pennsylvania, 1984-90

    USGS Publications Warehouse

    Hall, D.W.; Lietman, P.L.; Koerkle, E.J.

    1997-01-01

    The U.S. Geological Survey and the Pennsylvania Department of Environmental Protection conducted a study from 1984 to 1990 to determine theeffects of the implementation and practice of nutrient management [an agricultural best-management practice (BMP)] on the quality of surface runoff and ground water at a 55-acre crop and livestock farm in carbonate terrain nearEphrata, Pa. Implementation of nutrient management at Field-Site 2 resulted in application decreases of 33 percent for nitrogen and 29 percent for phosphorus. There wereno significant changes in nitrogen or phosphorusloads for a given amount of runoff from the pre-BMP to the post-BMP periods. However, less than 2 percent of the applied nutrients weredischarged with runoff throughout the study period.After the implementation of nutrient management, statistically significant decreases in concentrations of nitrate in ground-water samples occurred at threeof the four wells monitored throughout the pre- and post-BMP periods. The largest decreases in nitrate concentrations occurred at wells where samples hadthe largest nitrate concentrations prior to nutrient management. Changes in nitrogen applications to the contributing areas of five wells were correlated with nitrate concentrations of the well water. The correlations between the timing and amount of applied nitrogen and changes in ground-water quality met the four conditions that are characteristic of a cause-effect relation: an association, consistency, responsiveness, and a mechanism. Changes in ground-water nitrate concentrations lagged behind changes in loading of nitrogen fertilizers (primarily manure) by approximately 4 to 19 months.

  12. New insight into pesticide partition coefficient Kd for modelling pesticide fluvial transport: application to an agricultural catchment in south-western France.

    PubMed

    Boithias, Laurie; Sauvage, Sabine; Merlina, Georges; Jean, Séverine; Probst, Jean-Luc; Sánchez Pérez, José Miguel

    2014-03-01

    Pesticides applied on crops are leached with rainfall to groundwater and surface water. They threat the aquatic environment and may render water unfit for human consumption. Pesticide partitioning is one of the pesticide fate processes in the environment that should be properly formalised in pesticide fate models. Based on the analysis of 7 pesticide molecules (alachlor, atrazine, atrazine's transformation product deethylatrazine or DEA, isoproturon, tebuconazole and trifluralin) sampled from July 2009 to October 2010 at the outlet of the river Save (south-western France), the objectives of this study were (1) to check which of the environmental factors (discharge, pH, concentrations of total suspended matter (TSM), dissolved organic carbon (DOC) and particulate organic carbon (POC) could control the pesticide sorption dynamic, and (2) to establish a relationship between environmental factors, the partition coefficient Kd and the octanol/water distribution coefficient Kow. The comparison of physico-chemical parameters values during low flow and high flow shows that discharge, TSM and POC are the factors most likely controlling the pesticide sorption processes in the Save river network, especially for lower values of TSM (below 13mgL(-1)). We therefore express Kd depending on the widely literature-related variable Kow and on the commonly simulated variable TSM concentration. The equation can be implemented in any model describing the fluvial transport and fate of pesticides in both dissolved and sorbed phases, thus, Kd becomes a variable in time and space. The Kd calculation method can be applied to a wide range of catchments and organic contaminants.

  13. Hydrology and the hypothetical effects of reducing nutrient applications of water quality in the Bald Eagle Creek Headwaters, southeastern Pennsylvania prior to implementation of agricultural best-management practices

    USGS Publications Warehouse

    Fishel, D.K.; Langland, M.J.; Truhlar, M.V.

    1991-01-01

    The report characterizes a 0.43-square-mile agricultural watershed in York County, underlain by albite-chlorite and oligoclase-mica schist in the Lower Susquehanna River basin, that is being studied as part of the U.S. Environmental Protection Agency's Chesapeake Bay Program. The water quality of Bald Eagle Creek was studied from October 1985 through September 1987 prior to the implementation of Best-Management Practices to reduce nutrient and sediment discharge into Muddy Creek, a tributary to the Chesapeake Bay. About 88 percent of the watershed is cropland and pasture, and nearly 33 percent of the cropland is used for corn. The animal population is entirely dairy cattle. About 85,640 pounds of nitrogen (460 pounds per acre) and 21,800 pounds of phosphorus (117 pounds per acre) were applied to fields; 52 percent of the nitrogen and 69 percent of the phosphorus was from commercial fertilizer. Prior to fertilization, nitrate nitrogen in the soil ranged from 36 to 136 pounds per acre and phosphorus ranged from 0.89 to 5.7 pounds per acre in the top 4 feet of soil. Precipitation was about 18 percent below normal and streamflow about 35 percent below normal during the 2-year study. Eighty-four percent of the 20.44 inches of runoff was base flow. Median concentrations of total nitrogen and dissolved phosphorous in base flow were 0.05 and 0.04 milligrams per liter as phosphorus, respectively. Concentrations of dissolved nitrate in base flow increased following wet periods after crops were harvested and manure was applied. During the growing season, concentrations decreased similarly to those observed in carbonate-rock areas as nutrient uptake and evapotranspiration by corn increased. About 4,550 pounds of suspended sediment, 5,250 pounds of nitrogen, and 66.6 pounds of phosphorus discharged in base flow during the 2-year period. The suspended sediment load was about 232,000 pounds in stormflow from 26 storms that contributed 51 percent of the total stormflow. The

  14. Influence of Herbaceous Riparian Buffers on Fish and Amphibian Communities Within Channelized Headwater Streams in Central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbaceous riparian buffers are a widely used conservation practice in the United States for reducing nutrient, pesticide, and sediment loadings in agricultural streams. The importance of forested riparian zones for headwater streams has been documented, but the ecological impacts of herbaceous ripa...

  15. Influence of Physical Habitat and Agricultural Contaminants on Fishes within Agricultural Drainage Ditches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural drainage ditches are used within agricultural watersheds for the removal of excess water from agricultural fields. These headwater streams have been constructed or modified so they possess an enlarged trapezoidal cross-section, straightened channels, and riparian zones lacking woody veg...

  16. INDICATORS OF HYDROLOGIC PERMANENCE IN HEADWATER STREAMS

    EPA Science Inventory

    Headwater intermittent streams lie at the aquatic-terrestrial interface and represent much of our nation's stream miles. Recent court cases concerning the definition of jurisdictional waters under the Clean Water Act have illuminated a need to better understand the characteristi...

  17. Impact of land use changes on connectivity in a rural catchment with mild topography

    NASA Astrophysics Data System (ADS)

    Langhammer, Jakub; Ghaffari, Golaleh

    2016-04-01

    Concept of sediment connectivity and quantitative assessment of its spatial distribution became important tool for analysis of spatial connectivity of sediment transport processes in basins. Most of the first connectivity studies is focused on montane basins with high rates of erosion originating in steep slopes in headwater areas. However, less attention is paid to the mild landscapes in highland and lowland landscape, with often high connectivity. It applies to the rural areas where the sediment transport and erosion control are of key importance. Assessment of connectivity and its control in such environment thus can contribute to the efficient and sustainable landscape management. In our study we have tested applicability of the concept of index of sediment connectivity (IC) in mid-latitude rural catchment with mild topography and extensive share of arable land. The aim of the study was (i) to test the GIS-based IC calculation in specific topographic conditions, (ii) to assess the effects of land use changes on the sediment connectivity and (iii) to identify the landscape features affecting connection between hillslopes and stream channels. The study area - Loucka River Basin, Czech Republic with area of 386 sq km is located in highland landscape with 60% share of arable land. The basin study area has a reverse pattern of topography compared to the typical montane catchments - the extensive headwater areas, used for agriculture, are flat and are drained into steep valleys in downstream. The basin is equipped with long-term monitoring of suspended sediment transport. We have used the high resolution 5 meter DEM derived from aerial LiDAR scanning as a base for analysis of topographic controls of sediment connectivity and for calculation of connectivity topographic index. The index of connectivity was calculated in a multitemporal scale of two decades since 1990 to analyze the the changes of sediment connectivity and its spatial distribution in response to the

  18. Catchment scale afforestation for mitigating flooding

    NASA Astrophysics Data System (ADS)

    Barnes, Mhari; Quinn, Paul; Bathurst, James; Birkinshaw, Stephen

    2016-04-01

    After the 2013-14 floods in the UK there were calls to 'forest the uplands' as a solution to reducing flood risk across the nation. At present, 1 in 6 homes in Britain are at risk of flooding and current EU legislation demands a sustainable, 'nature-based solution'. However, the role of forests as a natural flood management technique remains highly controversial, due to a distinct lack of robust evidence into its effectiveness in reducing flood risk during extreme events. SHETRAN, physically-based spatially-distributed hydrological models of the Irthing catchment and Wark forest sub-catchments (northern England) have been developed in order to test the hypothesis of the effect trees have on flood magnitude. The advanced physically-based models have been designed to model scale-related responses from 1, through 10, to 100km2, a first study of the extent to which afforestation and woody debris runoff attenuation features (RAFs) may help to mitigate floods at the full catchment scale (100-1000 km2) and on a national basis. Furthermore, there is a need to analyse the extent to which land management practices, and the installation of nature-based RAFs, such as woody debris dams, in headwater catchments can attenuate flood-wave movement, and potentially reduce downstream flood risk. The impacts of riparian planting and the benefits of adding large woody debris of several designs and on differing sizes of channels has also been simulated using advanced hydrodynamic (HiPIMS) and hydrological modelling (SHETRAN). With the aim of determining the effect forestry may have on flood frequency, 1000 years of generated rainfall data representative of current conditions has been used to determine the difference between current land-cover, different distributions of forest cover and the defining scenarios - complete forest removal and complete afforestation of the catchment. The simulations show the percentage of forestry required to have a significant impact on mitigating

  19. Catchment scale multi-objective flood management

    NASA Astrophysics Data System (ADS)

    Rose, Steve; Worrall, Peter; Rosolova, Zdenka; Hammond, Gene

    2010-05-01

    techniques will include: controlling headwater drainage, increasing evapotranspiration and interception by creating new woodlands in the upper catchment areas, enabling coarse woody debris dams to slow down water flows through steep valleys, improving soil water storage potential by appropriate soil and crop management, retaining water on lowland flood meadows and wet woodland creation within the floodplain. The project, due to run from 2009 until 2013, incorporates hydrometric and water quality monitoring, together with hydrologic and hydraulic modelling in order to attempt to demonstrate the effect of land management changes on flood dynamics and flood risk management. To date, the project team have undertaken the fundamental catchment characterisation work to understand its physical setting and the interaction of the physical processes that influence the hydrological response of the catchment to incident precipitation. The results of this initial work has led to the identification of a suitably robust hydrometric monitoring network within the catchments to meet the needs of providing both quantitative evidence of the impacts of land management change on flood risk, together with generating good quality datasets for the validation and testing of the new hydrologic models. As the project aims to demonstrate ‘best practice' in all areas, the opportunity has been taken to install a network of automatic hydrometric monitoring equipment, together with an associated telemetry system, in order to maximise data coverage, accuracy and reliability. Good quality datasets are a critical requirement for reliable modelling. The modelling will also be expanded to incorporate climate change scenarios. This paper will describe the catchment characterisation work undertaken to date, the proposed land management changes in relation to flood risk management, the initial catchment hydraulic modelling work and the implementation of the new hydrometric monitoring network within the study area.

  20. Modelling overbank flow on farmed catchments taking into account spatial hydrological discontinuities

    NASA Astrophysics Data System (ADS)

    Moussa, R.; Tilma, M.; Chahinian, N.; Huttel, O.

    2003-04-01

    In agricultural catchments, hydrological processes are largely variable in space due to human impact causing hydrological discontinuities such as ditch network, field limits and terraces. The ditch network accelerates runoff by concentrating flows, drains the water table or replenishes it by reinfiltration of the runoff water. During extreme flood events, overbank flow occurs and surface pathflows are modified. The purpose of this study is to assess the influence of overbank flow on hydrograph shape during flood events. For that, MHYDAS, a physically based distributed hydrological model, was especially developed to take into account these hydrological discontinuities. The model considers the catchment as a series of interconnected hydrological unit. Runoff from each unit is estimated using a deterministic model based on the pounding-time algorithm and then routed through the ditch network using the diffusive wave equation. Overbank flow is modelled by modifying links between the hydrological units and the ditch network. The model was applied to simulate the main hydrological processes on a small headwater farmed Mediterranean catchment located in Southern France. The basic hydrometeorological equipment consists of a meteorological station, rain gauges, a tensio-neutronic and a piezometric measurement network, and eight water flow measurements. A multi-criteria and multi-scale approach was used. Three independent error criteria (Nash, error on volume and error on peak flow) were calculated and combined using the Pareto technique. Then, a multi-scale approach was used to calibrate and validate the model for the eight water flow measurements. The application of MHYDAS on the extreme ten flood events of the last decade enables to identify the ditches where overbank flows occur and to calculate discharge at various points of the ditch network. Results show that for the extreme flood event, more than 45% of surface runoff occur due to overbank flow. Discussion shows that

  1. Uncertainty assessment of a dominant-process catchment model of dissolved phosphorus transfer

    NASA Astrophysics Data System (ADS)

    Dupas, Rémi; Salmon-Monviola, Jordy; Beven, Keith J.; Durand, Patrick; Haygarth, Philip M.; Hollaway, Michael J.; Gascuel-Odoux, Chantal

    2016-12-01

    We developed a parsimonious topography-based hydrologic model coupled with a soil biogeochemistry sub-model in order to improve understanding and prediction of soluble reactive phosphorus (SRP) transfer in agricultural headwater catchments. The model structure aims to capture the dominant hydrological and biogeochemical processes identified from multiscale observations in a research catchment (Kervidy-Naizin, 5 km2). Groundwater fluctuations, responsible for the connection of soil SRP production zones to the stream, were simulated with a fully distributed hydrologic model at 20 m resolution. The spatial variability of the soil phosphorus content and the temporal variability of soil moisture and temperature, which had previously been identified as key controlling factors of SRP solubilization in soils, were included as part of an empirical soil biogeochemistry sub-model. The modelling approach included an analysis of the information contained in the calibration data and propagation of uncertainty in model predictions using a generalized likelihood uncertainty estimation (GLUE) "limits of acceptability" framework. Overall, the model appeared to perform well given the uncertainty in the observational data, with a Nash-Sutcliffe efficiency on daily SRP loads between 0.1 and 0.8 for acceptable models. The role of hydrological connectivity via groundwater fluctuation and the role of increased SRP solubilization following dry/hot periods were captured well. We conclude that in the absence of near-continuous monitoring, the amount of information contained in the data is limited; hence, parsimonious models are more relevant than highly parameterized models. An analysis of uncertainty in the data is recommended for model calibration in order to provide reliable predictions.

  2. Dissolved and particulate fluxes of copper through the Morlaix river estuary (Brittany, France): mass balance in a small estuary with strong agricultural catchment.

    PubMed

    Monbet, Ph

    2004-01-01

    Dissolved and particulate copper were measured over an annual cycle (12 surveys between February 1998 and January 1999) in the Morlaix Estuary (Brittany, France). These variations were investigated in both the water column and the benthic compartment in order to calculate fluxes of copper within estuary. In the water column, dissolved and particulate copper concentrations ranged from 0.6 to 19.0 nM and from 0.03 to 2.3 micromol g(-1), respectively. In the benthic compartment, copper concentrations in superficial sediment varied from 0.04 to 0.32 micromol g(-1) and from 7.6 to 80.5 nM in the pore waters. The results show that copper contents in the water column reached levels commonly observed in estuaries affected by heavy industrial activities. Agricultural activities, extensively developed on the drainage basin, may be responsible for the copper excess. Mass balance of copper indicates that the metal accumulated within the estuary with a rate ranging from 97 to 119 kg yr(-1).

  3. Impact of rainforest conversion on water yield, seasonal flow and floods in a tropical catchment in Central Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    Kleinhans, A.; Gerold, G.

    2003-04-01

    Smallholder agriculture is playing an important role in rainforest conversion in the humid tropics. After conversion by smallholders the created landscape is characterized by a patchwork of different land use types in ever smaller patches undergoing a gradual change from forest dominated patches via annual crops to perennial plantation interspersed by secondary forest, pasture and annual crops. Our mountainous research area along the rainforest margin area of the Lore Lindu National Park in Central Sulawesi, Indonesia shows in an exemplary manner this sequence of conversion with natural forest at the mountainous upland and perennial plantation at the lowland connected by a moving transition zone of annual crops and young plantation. There, we are investigating the hydrological responses to the gradual conversions on the hydrological behaviour of low flows and high flows in a small catchment area and the factors causing these changes. To fulfil the goal we use a modified catchment approach with three weirs including water level recorders along the river with each weir representative for one predominant land use type. This design allows to measure the influence of land use changes on the water fluxes with the undisturbed headwater catchment serving as a reference. Additionally the meteorological inputs are measured with two automatic weather stations and four automatic rain gauges. On plot scale 30 soil water content measurement plots have been installed and soil physical properties in the different land use types have been measured to validate the results on catchment scale. Since the measurements started in 2001 our first results show an increase in the yearly water yield in the recently logged transition zone in comparison to the natural forest. Especially during low flow conditions water yield from converted areas is higher in comparison to natural forest. Reasons can be found in the reduced evapotranspiration after removal of the natural forest canopy. Floods

  4. Carbon cycling and exports over diel and flood-recovery timescales in a subtropical rainforest headwater stream.

    PubMed

    Looman, Arún; Santos, Isaac R; Tait, Douglas R; Webb, Jackie R; Sullivan, Caroline A; Maher, Damien T

    2016-04-15

    Catchment headwaters comprise the majority of all stream length globally, however, carbon (C) dynamics in these systems remains poorly understood. We combined continuous measurements of pCO2 and radon ((222)Rn, a natural groundwater tracer) with discrete sampling for particulate organic, dissolved organic and inorganic carbon (POC, DOC, and DIC) to assess the short-term carbon dynamics of a pristine subtropical headwater stream in Australia, over contrasting hydrologic regimes of drought, flash-flooding and recovery. Observations over 23days revealed a shift from carbon losses dominated by CO2 outgassing under conditions of low flow (66.4±0.4% of carbon export) to downstream exports of carbon during the flood (87.8±9.7% of carbon export). DOC was the dominant form of downstream exports throughout the study (DOC:DIC:POC=0.82:0.05:0.13). The broadest diel variability among variables occurred during the drought phase, with diel variability up to 662μatmd(-1) (or 27μM[CO2*]d(-1)), 17μMd(-1) and 268Bqm(-3)d(-1) for pCO2, dissolved oxygen and (222)Rn, respectively. Diel dynamics indicated multiple interrelated drivers of stream water chemistry including groundwater seepage and in-stream metabolism. The catchment exported terrestrial carbon throughout the field campaign, with a mean net stream flux of 4.7±7.8mmolCm(-2)(catchment area)d(-1) which is equivalent to 1.4±2.3% of the estimated local terrestrial net primary production. Our observations highlight the importance of accounting for hydrological extremes when assessing the carbon budgets and ecosystem metabolism of headwater streams, and provide a first estimate of aquatic carbon exports from a pristine Australian subtropical rainforest.

  5. Hydroecological monitoring in the headwaters of the Volga River

    NASA Astrophysics Data System (ADS)

    Kuzovlev, Viacheslav V.; Zhenikov, Yuri N.; Zhenikov, Kyrill Y.; Shaporenko, Sergey I.; Haun, Stefan; Füreder, Leopold; Schletterer, Martin

    2016-04-01

    Europe's largest river, the Volga (3551 km), has experienced multiple stressors from human activities (i.e. the Volga Basin comprises about 40 % of the Russian population, 45 % of the country's industry and more than 50 % of its agriculture). During the research expedition "Upper Volga 2005" an assessment of hydrological, limnochemical and biological parameters was carried out by scientists from the Russian Federation and from Austria. The extensive sampling in 2005 showed that the free-flowing section of the Volga River, located upstream of Tver, represents conditions which are either reference or least disturbed - thus it can be considered as a refugial system for freshwater biota of the European lowlands. Subsequently three stretches in the headwaters of the Volga River (Rzhev, Staritsa, Tver) were selected for the monitoring programme "REFCOND_VOLGA", which is in operation since 2006. These locations correspond also with the sampling sites of ROSHYDROMET, i.e. at Tver physic-chemical samples are taken monthly and at Rzhev samples are taken in the main hydrological periods. The laboratory ship "ROSHYDROMET 11" conducted monthly cruises between Tver and Kalyazin (Ivankovskoye and Uglichskoye reservoirs on Volga) in the headwaters during the navigation period (May - October). This also includes measurements with ADCP, which further allow the analyses of the spatial distribution of the suspended solids within cross sections. In addition sediment fluxes were derived by using the acoustic backscatter signal strength from the acoustic current Doppler profiler (ADCP). We exemplify at the monitoring sites the spatial distribution of different sediments, i.e. choriotope types, according the longitudinal profile of the river. We show that it is highly influenced by morphodynamics in the different river sections and this corresponds with the zoobenthos fauna accordingly. This interdisciplinary approach, including sediment conditions, limnochemistry, hydrology and

  6. Sediment transport in steep forested catchments - An assessment of scale and disturbance

    NASA Astrophysics Data System (ADS)

    Hancock, G. R.; Hugo, J.; Webb, A. A.; Turner, L.

    2017-04-01

    Stream sediment loads (both bedload and suspended sediment) are problematic to measure due to the time and equipment needed. There is a dearth of such data sets globally let alone for Australia. However, such data are needed to quantify sediment transport type and rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. Here we present the findings from 8 steepslope forested catchments dominated by headwater streams (size range 15-100 ha) in south-eastern Australia where both bedload and suspended load have been measured over multiple years. The results demonstrate that suspended load is the dominant component and there is no consistent suspended to bedload ratio for the catchments. The suspended sediment to bedload ratio appears to be catchment specific. There was no relationship between total load (or bedload/suspended load) and average catchment slope, stream length, shape or any geomorphic descriptor. However catchment total load was found to be significantly related to catchment area. Of the 8 catchments examined here, 6 had been harvested for timber in previous decades (with large areas of forest removed) while 2 catchments had minimal disturbance (Control catchments). There was no difference in sediment loads from the harvested and Control catchments. The results demonstrate that although land disturbance had previously occurred the management practices employed in each catchment were effective in the long term. This provides confidence that the forest harvesting and subsequent management do not produce detrimental effects in the medium to long term. An assessment of erosion rates and likely soil production rates suggests that the catchments are eroding soil at the rate it is being produced.

  7. Comparison of drought occurrence in selected Slovak and Czech catchments

    NASA Astrophysics Data System (ADS)

    Fendekova, Miriam; Fendek, Marian; Porubska, Diana; Hanel, Martin; Horacek, Stanislav; Martinkova, Marta; Vizina, Adam

    2014-05-01

    The presented study is focused on the analysis and comparison of hydrological drought occurrence, development and duration in six small to middle sized catchments in the Czech Republic (CZ) and Slovakia. The main questions to be answered are: (1) are there correlations between the physical conditions in the catchments and drought occurrence, and (2) does the spatial trend of drought occurrence exist. The Žitava catchment is located in the central western part of Slovakia having runoff dominated by rainfall with the contribution of snow melting during the spring period. The Belá River catchment is located on the contact of Západné and Vysoké Tatry Mts. in the north of Slovakia. The runoff is snow to snow-rain combined type. The Ľupčianka catchment is located on the northern slopes of the Nízke Tatry Mts. in the northern part of the central Slovakia. The runoff regime is snow-rain combined in the upper part of the catchment, and of rain-snow type in the rest of catchment. The Rakovnický potok brook (CZ) has its spring in Rakovnická pahorkatina hilly land. Runoff is dominated by rainfall, quite heavily influenced by water uptakes in the catchment. The Teplá River (CZ) originates in peat meadows in the western part of the Czech Republic. Runoff is dominated by rainfall. The Metuje catchment (CZ) is formed by Adršsbach-Teplické stěny Upland. The headwater part is typical by deeply incest valleys, table mountains and pseudokarst caves. The discharge is fed dominantly by groundwater. The streamflow drought was characterized using discharge data, the groundwater drought using the base flow values. The local minimum method was used for base flow separation. The threshold level method (Q80, BF80) and the sequent peak algorithm were used for calculation of drought duration in discharge and base flow time series. The data of the same three decades of the common period (1971 - 1980, 1981 - 1990 and 1991 - 2000) were used. The resulting base flow values along with

  8. Unraveling brackish groundwater - surface water interaction in an agricultural field using direct measurements at the field scale

    NASA Astrophysics Data System (ADS)

    Delsman, Joost; Waterloo, Maarten; Groen, Michel; Groen, Koos

    2014-05-01

    Understanding the interaction between groundwater and surface water is important for a myriad of reasons, including flow forecasting, nutrient transport, and water allocation for agriculture and other water users. This understanding is especially important in deep polder areas in the Netherlands, where brackish groundwater seepage (upward flowing regional groundwater) results in a significant salt load to surface water, and may damage crops if salts reach the rootzone in dry summers. Research on groundwater - surface water interaction historically focused on relatively pristine headwater catchments, only recently shifting somewhat to agricultural catchments. The latter pose specific research challenges, as agricultural activities and active water management can have a significant influence on hydrology. A brackish seepage flux, with a different density as precipitation, may significantly influence flow paths to surface water. Research on this specific topic is, however, lacking. We therefore investigated the interaction between groundwater and surface water in an agricultural catchment with a significant brackish seepage flux. In addition, we investigated the effects of intake of fresh water during periods of precipitation deficits, a common management strategy in lowland regions. We instrumented an agricultural ditch to enable direct, 15 min interval measurements of water fluxes and salinity to both agricultural drains and the ditch separately. These measurements are supported by piezometer nests, soil moisture sensors, temperature sensors, geophysics and a meteorological tower. Measurements focused on the summer period and were taken during two measurement periods: May 2012 - November 2012, and April 2013 - October 2013. Our measurements allowed for a direct, high-frequency separation of hydrological flow routes on this agricultural field between flow to agricultural drains and the ditch. The salinity of seepage water allowed for a relatively easy separation of

  9. Nutrient export from catchments on forested landscapes reveals complex nonstationary and stationary climate signals

    NASA Astrophysics Data System (ADS)

    Mengistu, Samson G.; Quick, Christopher G.; Creed, Irena F.

    2013-06-01

    Headwater catchment hydrology and biogeochemistry are influenced by climate, including linear trends (nonstationary signals) and climate oscillations (stationary signals). We used an analytical framework to detect nonstationary and stationary signals in yearly time series of nutrient export [dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate (NO3--N), and total dissolved phosphorus (TDP)] in forested headwater catchments with differential water loading and water storage potential at the Turkey Lakes Watershed in Ontario, Canada. We tested the hypotheses that (1) climate has nonstationary and stationary effects on nutrient export, the combination of which explains most of the variation in nutrient export; (2) more metabolically active nutrients (e.g., DON, NO3--N, and TDP) are more sensitive to these signals; and (3) catchments with relatively low water loading and water storage capacity are more sensitive to these signals. Both nonstationary and stationary signals were identified, and the combination of both explained the majority of the variation in nutrient export data. More variation was explained in more labile nutrients (DON, NO3--N, and TDP), which were also more sensitive to climate signals. The catchment with low-water storage potential and low water loading was most sensitive to nonstationary and stationary climatic oscillations, suggesting that these hydrologic features are characteristic of the most effective sentinels of climate change. The observed complex links between climate change, climatic oscillations, and water nutrient fluxes in headwater catchments suggest that climate may have considerable influence on the productivity and biodiversity of surface waters, in addition to other drivers such as atmospheric pollution.

  10. Hydrology of a wetland-dominated headwater basin in the Boreal Plain, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Wells, Corey; Ketcheson, Scott; Price, Jonathan

    2017-04-01

    This study provides an in-depth analysis of the runoff generation dynamics and hydrological connectivity across upland-wetland transitions within a wetland-dominated headwater basin in the Western Boreal Plain (WBP), Canada. Basin runoff response between and among years was driven largely by differences in the timing and magnitude of precipitation relative to potential evapotranspiration, hence antecedent moisture conditions, which varied markedly over the four-year study (April-Sept). Runoff coefficients for individual precipitation events ranged from <1 to >90% depending on storm dynamics and antecedent conditions. Owing to its higher elevation, the basin received 55% more precipitation per month on average compared to 30-year climate normals and an average of 86 mm more precipitation per season than the nearby regional weather station. The wetland and adjacent forestlands became coupled during intermittent wet periods which generated substantial runoff. The findings of the current study suggest that, in contrast to conventional conceptual models, headwater catchments within the subhumid WBP have the capacity to generate significant runoff throughout the snow-free period. This has important implications for wetland maintenance and represents an important water delivery mechanism for downstream ecosystems where excess water is scarce.

  11. Spatio-temporal Variability of Controls on Water Balance Components in a Western Mountainous Headwater Basin

    NASA Astrophysics Data System (ADS)

    Kelleher, C.; Wagener, T.; McGlynn, B. L.; Marshall, L. A.; Jencso, K. G.

    2011-12-01

    Headwater basins represent a large portion of the stream network in the United States and provide crucial but largely unquantified ecosystem services, including export of water and nutrients to downstream sources and habitat for sensitive aquatic species. Investigating controls on hydrologic fluxes within these headwaters is important for understanding how these basins might respond to change in climate or land use. Our work focuses on characterizing controls on water balance components within the Tenderfoot Creek Experimental Forest (TCEF) via experimental data-modeling synthesis. Extensive monitoring within the basin offers the opportunity to compare model behavior against multiple water balance components and hydrologic fluxes, including snowmelt, snow water equivalent, evapotranspiration, catchment storage, and streamflow. We model the basin using the Distributed Hydrology Vegetation Soil Model (DHSVM) and apply variance-based global sensitivity analysis to quantify the spatio-temporal variability of controls on different hydrologic fluxes across the study domain. The results provide a unique opportunity for testing the consistency between DHSVM and our perception of the watershed processes in the TCEF.

  12. Hydrogeomorphic connectivity on roads crossing in rural headwaters and its effect on stream dynamics.

    PubMed

    Thomaz, Edivaldo L; Peretto, Gustavo T

    2016-04-15

    Unpaved roads are ubiquitous features that have been transforming the landscape through human history. Unpaved roads affect the water and sediment pathways through a catchment and impacts the aquatic ecosystem. In this study, we describe the effect of unpaved road on the hydrogeomorphic connectivity at the rural headwater scale. Measurement was based on the stream crossing approach, i.e., road superimposing the drainage system. We installed a Parshall flume coupled with single-stage suspended sediment sampler at each stream crossing. In addition, we displayed our monitoring scheme with an upscaling perspective from second-order to third-order stream. We concluded that the road-stream coupling dramatically changed the stream dynamic. The increase of discharge caused by roads at the headwater was 50% larger compared to unaffected streams. Additionally, suspended sediment concentration enhancement at stream crossings ranged from to 413% at second-order streams to 145% at third-order streams. The landform characteristics associated with the road network produced an important hydrogeomorphic disruption in the landscape. As a result, the sediment filter function of the riparian zone was reduced dramatically. Therefore, we recommend that projects for aquatic system restoration or conservation in rural landscape consider the role of the road network on stream dynamics.

  13. DOM composition in an agricultural watershed: assessing patterns and variability in the context of spatial scales

    USGS Publications Warehouse

    Hernes, Peter J.; Spencer, Robert G. M.; Dyda, Rachel Y.; Pellerin, Brian A.; Bachand, Philip A. M.; Bergamaschi, Brian A.

    2013-01-01

    Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled synoptically in order to investigate the extent to which dissolved organic carbon (DOC) concentrations and compositions from throughout the catchment are represented at the mouth. DOC concentrations ranged from 1.8 to 13.9 mg L−1, with the lowest values in headwater 1st and 2nd order streams, and the highest values associated with flood irrigation. Carbon-normalized vanillyl phenols varied from 0.05 to 0.67 mg 100 mg OC−1 (0.37 mean), indicative of considerable contributions from vascular plants. DOC concentrations and compositions at the mouth appear to be primarily influenced by land use (agriculture) in the lower reaches, and therefore very little of the headwater chemistry (1st and 2nd order streams) can be discerned from the chemistry at or near the mouth (3rd and 4th order streams), indicating the need for synoptic sampling to capture the breadth of organic carbon cycling within a catchment. Field sampling during irrigation showed the large impact that flood irrigation can have on DOC concentrations and compositions, likely a primary cause of significantly elevated Willow Slough DOC concentrations during the summer irrigation season. Optical proxies exhibited varying degrees of correlation with chemical measurements, with strongest relationships to DOC and dissolved lignin (r2 = 0.95 and 0.73, respectively) and weaker relationships to carbon-normalized lignin yields and C:V (r2 from 0.31 to 0.42). Demonstrating the importance of matching scale to processes, we found no relationship between dissolved lignin concentrations and total suspended sediments (TSS) across all sites, in contrast to the strong relationship observed in weekly samples at the mouth. As DOC concentrations and compositions at the mouth of Willow Slough are closely tied to anthropogenic activities within the catchment, future changes in land-use driven by climate

  14. The Age of Terrestrial Carbon Export and Rainfall Intensity in a Temperate River Headwater System

    NASA Astrophysics Data System (ADS)

    Tittel, J.; Büttner, O.; Freier, K.; Heiser, A.; Sudbrack, R.; Ollesch, G.

    2013-12-01

    Riverine dissolved organic carbon (DOC) supports the production of estuaries and coastal ecosystems, constituting one of the most actively recycled pools of the global carbon cycle. A substantial proportion of DOC entering oceans is highly aged, but its origins remain unclear. Significant fluxes of old DOC have never been observed in temperate headwaters where terrestrial imports take place. Here, we studied the radiocarbon age of DOC in three streams draining forested headwater catchments of the river Mulde (Ore Mountains, Germany). We found modern DOC at moderately dry and moderately wet conditions as well as at high discharges during snowmelt. Old groundwater carbon contributed to stream DOC during the summer drought, although the yield was negligible. However, in a four-week summer precipitation event DOC aged at between 160 and 270 years was delivered into the watershed. In one stream, the DOC was modern but depleted in radiocarbon compared to other hydrological conditions. The yield was substantial and corresponded to 20 to 52% of the annual DOC yields in wet and dry years, respectively. Time-integrating samples of a downstream reservoir also revealed modern DOC ages under moderate conditions and old DOC from the rainfall event. Earlier studies suggested that increasing precipitation escalates the contribution of modern DOC from topsoil layers to surface runoff. Our results demonstrate a step change occurring if rainfall intensities increase and become extreme; then the consequences lead to the mobilization of old carbon in exceptionally high concentrations. The runoff/precipitation ratios of rainfall events indicated that during extreme events upland areas of the catchments were hydrologically connected to the stream and upland DOC was activated. Furthermore, the analysis of long-term data suggested that the DOC export in extreme precipitation events added to the annual yield and was not compensated for by lower exports in remaining periods. We conclude that

  15. The role of event water, a rapid shallow flow component, and catchment size in summer stormflow

    USGS Publications Warehouse

    Brown, V.A.; McDonnell, Jeffery J.; Burns, Douglas A.; Kendall, C.

    1999-01-01

    Seven nested headwater catchments (8 to 161 ha) were monitored during five summer rain events to evaluate storm runoff components and the effect of catchment size on water sources. Two-component isotopic hydrograph separation showed that event-water contributions near the time of peakflow ranged from 49% to 62% in the 7 catchments during the highest intensity event. The proportion of event water in stormflow was greater than could be accounted for by direct precipitation onto saturated areas. DOC concentrations in stormflow were strongly correlated with stream 18O composition. Bivariate mixing diagrams indicated that the large event water contributions were likely derived from flow through the soil O-horizon. Results from two-tracer, three-component hydrograph separations showed that the throughfall and O-horizon soil-water components together could account for the estimated contributions of event water to stormflow. End-member mixing analysis confirmed these results. Estimated event-water contributions were inversely related to catchment size, but the relation was significant for only the event with greatest rainfall intensity. Our results suggest that perched, shallow subsurface flow provides a substantial contribution to summer stormflow in these small catchments, but the relative contribution of this component decreases with catchment size.Seven nested headwater catchments (8 to 161 ha) were monitored during five summer rain events to evaluate storm runoff components and the effect of catchment size on water sources. Two-component isotopic hydrograph separation showed that event-water contributions near the time of peakflow ranged from 49% to 62% in the 7 catchments during the highest intensity event. The proportion of event water in stormflow was greater than could be accounted for by direct precipitation onto saturated areas. DOC concentrations in stormflow were strongly correlated with stream 18O composition. Bivariate mixing diagrams indicated that the

  16. HEADWATER INTERMITTENT STREAMS STUDY: COLLABORATION ACROSS THE NATION

    EPA Science Inventory

    Headwater streams are the most abundant and widespread of our nation's surface waters, yet little guidance is available specific to these resources. Headwater streams lie at the terrestrial-aquatic interface, both spatially because of their narrow channels and landscape position ...

  17. Forested headwaters mitigate pesticide effects on macroinvertebrate communities in streams: Mechanisms and quantification.

    PubMed

    Orlinskiy, Polina; Münze, Ronald; Beketov, Mikhail; Gunold, Roman; Paschke, Albrecht; Knillmann, Saskia; Liess, Matthias

    2015-08-15

    Pesticides impact invertebrate communities in freshwater ecosystems, leading to the loss of biodiversity and ecosystem functions. One approach to reduce such effects is to maintain uncontaminated stream reaches that can foster recovery of the impacted populations. We assessed the potential of uncontaminated forested headwaters to mitigate pesticide impact on the downstream macroinvertebrate communities in 37 streams, using the SPEARpesticides index. Pesticide contamination was measured with runoff-triggered techniques and Chemcatcher® passive samplers. The data originated from 3 field studies conducted between 1998 and 2011. The proportion of vulnerable species decreased significantly after pesticide exposure even at low toxicity levels (-4headwaters was not associated with reduced pesticide exposure 3 km downstream and did not reduce the loss of vulnerable taxa after exposure. Nevertheless, forested headwaters were associated with the absence of long-term pesticide effects on the macroinvertebrate community composition. We conclude that although pesticides can cause the loss of vulnerable aquatic invertebrates even at low toxicity levels, forested headwaters enhance the recovery of vulnerable species in agricultural landscapes.

  18. Connectivity of overland flow by drainage network expansion in a rain forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Beate; Zimmermann, Alexander; Turner, Benjamin L.; Francke, Till; Elsenbeer, Helmut

    2014-02-01

    Soils in various places of the Panama Canal Watershed feature a low saturated hydraulic conductivity (Ks) at shallow depth, which promotes overland-flow generation and associated flashy catchment responses. In undisturbed forests of these areas, overland flow is concentrated in flow lines that extend the channel network and provide hydrological connectivity between hillslopes and streams. To understand the dynamics of overland-flow connectivity, as well as the impact of connectivity on catchment response, we studied an undisturbed headwater catchment by monitoring overland-flow occurrence in all flow lines and discharge, suspended sediment, and total phosphorus at the catchment outlet. We find that connectivity is strongly influenced by seasonal variation in antecedent wetness and can develop even under light rainfall conditions. Connectivity increased rapidly as rainfall frequency increased, eventually leading to full connectivity and surficial drainage of entire hillslopes. Connectivity was nonlinearly related to catchment response. However, additional information on factors such as overland-flow volume would be required to constrain relationships between connectivity, stormflow, and the export of suspended sediment and phosphorus. The effort to monitor those factors would be substantial, so we advocate applying the established links between rain event characteristics, drainage network expansion by flow lines, and catchment response for predictive modeling and catchment classification in forests of the Panama Canal Watershed and in similar regions elsewhere.

  19. Imaging hydrological processes in headwater riparian seeps with time-lapse electrical resistivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The activation of subsurface seepage in response to precipitation events represents a potentially important pathway of nitrogen (N) delivery to streams in agricultural catchments. We used electrical resistivity imaging (ERI) and shallow piezometers to elucidate how seep and non-seep areas within the...

  20. Alternative methods to determine headwater benefits

    SciTech Connect

    Bao, Y.S.; Perlack, R.D.; Sale, M.J.

    1997-11-10

    In 1992, the Federal Energy Regulatory Commission (FERC) began using a Flow Duration Analysis (FDA) methodology to assess headwater benefits in river basins where use of the Headwater Benefits Energy Gains (HWBEG) model may not result in significant improvements in modeling accuracy. The purpose of this study is to validate the accuracy and appropriateness of the FDA method for determining energy gains in less complex basins. This report presents the results of Oak Ridge National Laboratory`s (ORNL`s) validation of the FDA method. The validation is based on a comparison of energy gains using the FDA method with energy gains calculated using the MWBEG model. Comparisons of energy gains are made on a daily and monthly basis for a complex river basin (the Alabama River Basin) and a basin that is considered relatively simple hydrologically (the Stanislaus River Basin). In addition to validating the FDA method, ORNL was asked to suggest refinements and improvements to the FDA method. Refinements and improvements to the FDA method were carried out using the James River Basin as a test case.

  1. The role of bedrock groundwater in rainfall-runoff response at hillslope and catchment scales

    NASA Astrophysics Data System (ADS)

    Gabrielli, C. P.; McDonnell, J. J.; Jarvis, W. T.

    2012-07-01

    SummaryBedrock groundwater dynamics in headwater catchments are poorly understood and poorly characterized. Direct hydrometric measurements have been limited due to the logistical challenges associated with drilling through hard rock in steep, remote and often roadless terrain. We used a new portable bedrock drilling system to explore bedrock groundwater dynamics aimed at quantifying bedrock groundwater contributions to hillslope flow and catchment runoff. We present results from the Maimai M8 research catchment in New Zealand and Watershed 10 (WS10) at the H.J. Andrews Experimental Forest in Oregon, USA. Analysis of bedrock groundwater at Maimai, through a range of flow conditions, revealed that the bedrock water table remained below the soil-bedrock interface, indicating that the bedrock aquifer has minimal direct contributions to event-based hillslope runoff. However, the bedrock water table did respond significantly to storm events indicating that there is a direct connection between hillslope processes and the underlying bedrock aquifer. WS10 groundwater dynamics were dominated by fracture flow. A highly fractured and transmissive zone within the upper one meter of bedrock conducted rapid lateral subsurface stormflow and lateral discharge. The interaction of subsurface stormflow with bedrock storage directly influenced the measured hillslope response, solute transport and computed mean residence time. This research reveals bedrock groundwater to be an extremely dynamic component of the hillslope hydrological system and our comparative analysis illustrates the potential range of hydrological and geological controls on runoff generation in headwater catchments.

  2. Very long hillslope transport timescales determined from uranium-series isotopes in river sediments from a large, tectonically stable catchment

    NASA Astrophysics Data System (ADS)

    Suresh, P. O.; Dosseto, A.; Hesse, P. P.; Handley, H. K.

    2014-10-01

    The uranium-series isotopic compositions of soils and sediments evolve in response to time and weathering conditions. Therefore, these isotopes can be used to constrain the timescales of river sediment transport. Catchment evolution depends on the sediment dynamic timescales, on which erosion imparts a major control. Erosion rates in tectonically stable catchments are expected to be lower than those in tectonically active catchments, implying longer sediment residence times in tectonically stable catchments. Mineralogical, elemental and isotopic data are presented for modern channel sediments, alluvial and colluvial deposits from the Murrumbidgee River, a large catchment in the passive margin highlands of south-eastern Australia and three of its tributaries from the headwaters to the alluvial plain. Low variability in Si-based Weathering Index indicates that there is little chemical weathering occurring in the Murrumbidgee River during sediment transport. However, quartz content increases and plagioclase content decreases downstream, indicating progressive mineralogical sorting and/or physical comminution with increasing transport distance. U-series isotopic ratios in the Murrumbidgee River trunk stream sediments show no systematic downstream variation. The weathering ages of sediments within the catchment were determined using a loss-gain model of U-series isotopes. Modern sediments from a headwater tributary, the Bredbo River at Frogs Hollow, have a weathering age of 76 ± 30 kyr but all other modern channel sediments from the length of the Murrumbidgee River and its main tributaries have weathering ages ∼400 ± 180 kyr. The two headwater colluvial deposits have weathering ages of 57 ± 13 and 47 ± 11 kyr, respectively. All the alluvial deposits have weathering ages similar to those of modern sediments. No downstream trend in weathering age is observed. Together with the soil residence time of up to 30 kyr for ridge-top soils at Frogs Hollow in the upper

  3. Catchment Prediction In Changing Environments (CAPICHE): A Model Inter-Comparison Experiment

    NASA Astrophysics Data System (ADS)

    Hutton, Christopher; Nijzink, Remko; Pechlivanidis, Ilias; Capell, René; Wagener, Thorsten; Freer, Jim; Han, Dawei; Hrachowitz, Markus; Arheimer, Berit

    2016-04-01

    In order to improve societal resilience to the impacts of changes in climate and land-use, improved understanding of how catchments respond to changing forcing conditions is required. Such understanding may help better identify the range of effective interventions to improve overall integrated catchment management. For example, re-foresting catchment headwaters may reduce high flows, but also reduce low flows through increased evapotranspiration, creating a potential trade-off that needs to be reliably understood when considering benefits for both water supply and flood mitigation. Catchment modelling may be useful to inform such management decisions by simulating future forcing changes, so that we can assess the relative benefits of different catchment management scenarios. However, numerical models are known to be uncertain, and their ability to simulate future change is compromised by the fact that model parameters can show non-stationary and compensatory effects for different forcing conditions, notwithstanding errors and uncertainties in the future forcings themselves. In order to first identify, and second develop the most appropriate models to simulate catchments under environmental change, we argue that model inter-comparisons are required that move beyond a simple comparison of predictive performance alone, towards a controlled comparison of how different models simulate change. We present the development of a methodology for model inter-comparison under changing forcings to analyse, in this case, how models simulate landscape change, built upon time-varying sensitivity analysis of model parameters. First, for a given catchment, hydrologic signatures are calculated over consecutive windows covering the period of forcing change to analyse how the catchment responds hydrologically to change. Then, each model is calibrated to each window, and within each window, to each signature, which allows us to analyse the time-varying relationship between catchment

  4. 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.

  5. Standardised survey method for identifying catchment risks to water quality.

    PubMed

    Baker, D L; Ferguson, C M; Chier, P; Warnecke, M; Watkinson, A

    2016-06-01

    This paper describes the development and application of a systematic methodology to identify and quantify risks in drinking water and recreational catchments. The methodology assesses microbial and chemical contaminants from both diffuse and point sources within a catchment using Escherichia coli, protozoan pathogens and chemicals (including fuel and pesticides) as index contaminants. Hazard source information is gathered by a defined sanitary survey process involving use of a software tool which groups hazards into six types: sewage infrastructure, on-site sewage systems, industrial, stormwater, agriculture and recreational sites. The survey estimates the likelihood of the site affecting catchment water quality, and the potential consequences, enabling the calculation of risk for individual sites. These risks are integrated to calculate a cumulative risk for each sub-catchment and the whole catchment. The cumulative risks process accounts for the proportion of potential input sources surveyed and for transfer of contaminants from upstream to downstream sub-catchments. The output risk matrices show the relative risk sources for each of the index contaminants, highlighting those with the greatest impact on water quality at a sub-catchment and catchment level. Verification of the sanitary survey assessments and prioritisation is achieved by comparison with water quality data and microbial source tracking.

  6. Influence of hillslope-channel coupling on two mountain headwater streams, Swiss National Park, Switzerland

    NASA Astrophysics Data System (ADS)

    Schoch, Anna; Hoffmann, Thomas; Dikau, Richard

    2014-05-01

    Sediment fluxes in mountain headwater streams are strongly conditioned by sediment supply from hillslopes and thus hillslope-channel coupling, defined as linkages connecting slopes and channels through sediment transport processes. Sediment supply from hillslopes can have major influences on channel characteristics. The main goal of my research is to achieve a better understanding of these influences on mountain headwater streams in two study areas. This is conducted through the investigation of "channel-reach morphology" according to MONTGOMERY AND BUFFINGTON (1997), morphometric and sedimentological characteristics of the channels and analysis of the slope-channel coupling system. The study was conducted in two valleys in the Swiss National Park, i.e. Val dal Botsch (VdB) and Val Mueschauns (VMu). In both headwaters slopes and channel are coupled effectively due to the small spatial vicinity and frequent debris flow processes connecting the two system components. Both catchments were glaciated in the Pleistocene but show contrasting glacial imprints today. While VdB has a V-shaped morphometry that is dominated by unconsolidated sediments (mainly talus and moraine material), VMu is U-shaped in the upper valley segments and the surface is mainly covered with bedrock. Several methods for data collection and analyses were used: (1) Channel-reach morphology classification, (2) DEM-based analysis of long profiles, ksn-values, slope-area plots and measurement of cross sections in the field, (3) investigation of sedimentological characteristics with pebble counts as well as (4) mapping of recent linkages between slopes and channel and determination of connectivity (effectivity of coupling) using a heuristic approach. The results show that sediment input into both headwater streams is dominated by debris flows. The debris flow catchments, as parts of the slope system, have the highest connectivity to the channels. Channel changes are greatest where debris flows cause

  7. Linking catchment structure to hydrologic function: Implications of catchment topography for patterns of landscape hydrologic connectivity and stream flow dynamics

    NASA Astrophysics Data System (ADS)

    Jencso, K. G.; McGlynn, B. L.; Marshall, L. A.

    2010-12-01

    The relationship between catchment structure (topography and topology), stream network hydrologic connectivity, and runoff response remains poorly understood. Hillslope-riparian-stream (HRS) water table connectivity serves as the hydrologic linkage between a catchment’s uplands and the channel network and facilitates the transmission of water and solutes to streams. While there has been tremendous interest in the concept of hydrological connectivity to characterize catchments, there are relatively few studies that have quantified hydrologic connectivity at the stream network and catchment scales. Here, we examine how catchment topography influenced patterns of stream network HRS connectivity and resultant runoff dynamics across 11 nested headwater catchments in the Tenderfoot Creek Experimental Forest (TCEF), MT. This study extends the empirical findings of Jencso et al. (2009) who found a strong linear relationship (r2 = 0.92) between the upslope accumulated area (UAA) and annual duration of shallow ground water table connectivity observed across 24 HRS transects (146 groundwater recording wells) within the TCEF. We applied this relationship to the entire stream network to quantify the frequency distribution of stream network connectivity through time (as a function of UAA) and ascertain its relationship to catchment-scale runoff dynamics. Each catchment’s estimated connectivity duration curve (CDC) was highly related to its flow duration curve (FDC); albeit the rate of change of runoff with respect to stream network connectedness varied significantly across catchments. To ascertain potential reasons for these differences we compared the slope of each catchment’s CDC-FDC relationship (annual, peak, transition and baseflow periods) in multiple linear models against median values of common terrain indices and land cover-vegetation characteristics. Significant predictors (p<0.05) included the flow path distance to the creek (DFC), the flow path gradient to the

  8. The Carbon Cycle at the Nile Headwaters

    NASA Astrophysics Data System (ADS)

    Jones, Michael; Saunders, Matthew

    2014-05-01

    The carbon cycle at the Nile headwaters M B Jones, School of Natural Sciences, Trinity College, University of Dublin, Dublin 2, Ireland M Saunders, Environmental and Biochemical Sciences Group, The James Hutton Institute, Aberdeen, Scotland River systems play an integral role in the global carbon cycle by connecting the terrestrial biosphere, the atmosphere and the oceans. Extensive wetland systems, such as those found in the Amazon region, have been shown to export significant amounts of carbon to river waters as dissolved carbon dioxide (CO2) that can be transported and emitted hundreds of km downstream. The assessment of both regional and global carbon budgets could therefore be improved by quantifying these lateral carbon fluxes, especially from highly productive temporarily or permanently flooded areas where substantial CO2 evasion from inland waters can occur. The Nile is the longest river in the world and the headwaters are located in the extensive Papyrus dominated wetlands in central Africa that are associated with Lake Victoria. From its source the White Nile flows northwards through wetlands in Uganda and Sudan before it joins the Blue Nile. Papyrus wetlands have been shown to be some of the most productive global ecosystems, with recorded rates of aerial net primary productivity of up to 3.09 kg C m-2 yr-1. In addition, where anaerobic conditions occur they also accumulate large amounts of carbon in the form of peat, and under these circumstances they represent a significant carbon sink. However, as water moves through these wetlands and is exchanged with surrounding rivers and lakes significant quantities of dissolved organic and inorganic carbon as well as suspended particulate organic matter are exported, which are either released further downstream by degassing, decomposition or deposition. Information on such losses from these wetland ecosystems is extremely sparse but in order to better constrain ecosystem scale carbon dynamics more accurate

  9. Relationship Between Storm Hydrograph Components and Subsurface Flow Processes in a Hilly Headwater Basin, Toyota, Japan

    NASA Astrophysics Data System (ADS)

    Tsujimura, M.; Asai, K.; Takei, R.

    2001-05-01

    Temporal and spatial distribution of tracer elements and subsurface flow processes were investigated to study relationship between storm hydrograph components and behavior of subsurface water in a headwater catchment of Toyota Hill, Aichi prefecture, central Japan. The catchment has an area of 0.857 ha with an altitude of 60 to 100 m, and is underlain by granite. The soil depth revealed by sounding test ranges from 0.5 to 4.0 m. Rain, stream, soil and ground waters were sampled once in a week, and the stream water was sampled at 5 to 60 minute intervals during rainstorms. The pressure head of subsurface water was monitored using tensiometers and piezometers nests, and the stream flow was monitored using V-notch weir. The stable isotopic ratios of deuterium and oxygen 18 and inorganic ion concentrations were determined on all water samples. The oxygen 18 isotopic ratio in stream water decreased with rainfall during the rainstorms. The ratio of event water component to the total runoff water at the peak discharge ranged from 16 to 92 %, and the event water ratio correlated with the peak discharge rate and rainfall intensity. The tesiometric data showed that the shallow subsurface water with low isotopic ratios at the lower slope discharged directly to the stream during the heavy rainstorms. The shallow subsurface flow at the lower slope and overland flow on the raiparian zone contributed much to the stream water chemistry during heavy rainstorms.

  10. Frequent summer droughts homogenize landscape vegetation patterns at the catchment scale

    NASA Astrophysics Data System (ADS)

    Hwang, T.; Band, L. E.; Miniat, C. F.; Song, C.

    2013-12-01

    Mountain watersheds are primary sources of freshwater, carbon sequestration, and other ecosystem services. There is significant interest in the effects of climate change and variability on the patterns and processes of these services over short to long time scales. Forest ecosystems are sensitive to interannual to long-term hydroclimate variability and they adjust leaf area and duration in response to water or nutrient availability. Therefore, much of the impact of hydroclimate variability and resulting water yield is manifested in vegetation dynamics in space and time since they provide 'a window into the underlying water balance' (Sivapalan, 2005). Landsat TM provides a three-decade multispectral imagery record which enables us to estimate changes in landscape vegetation patterns at fine resolution (30 m) over the period of global warming. We characterize the catchment-scale vegetation patterns with the ';hydrologic vegetation gradient (HVG)' (defined as the gradient of the normalized difference vegetation index (NDVI) along hydrologic flowpaths; Hwang et al., 2012) and the standard deviations of NDVI from historic Landsat TM images at six preserved headwater catchments in Coweeta Hydrologic Laboratory, NC. We also analyze long-term seasonal water balances and low flow patterns from observed hydrologic records. We found that vegetation gradients along hydrologic flowpaths have decreased with hydroclimate change due to the decreases in upslope subsidies. This study shows that forest ecosystems are responding to the variability in hydroclimate regime rather than the mean, especially to drought. This study provides mechanistic understanding of shifts in hydrologic and ecologic regimes in humid mountainous landscapes with hydroclimate change. It also presents the potential to use emergent vegetation patterns in space and time for the inference of long-term hydrologic behavior. Figure 1. Temporal patterns of the hydrologic vegetation gradient and standard deviations

  11. Quantifying Hydrological Ecosystem Services of Various Land Covers and Uses on Small Experimental Catchments within the Panama Canal Watershed: The Agua Salud Project

    NASA Astrophysics Data System (ADS)

    Crouch, T. D.; Ogden, F. L.; Agua Salud Project

    2011-12-01

    As a part of the Agua Salud Project, a baseline characterization of hydrologic processes on the small catchment scale (~0.24 to 2.0 km2) is assessed across different land uses and covers typical to rural Panama. The land covers being monitored include a mature secondary forest, a disturbed catchment with a mosaic of various aged secondary growth and agricultural use, an active pasture and a monoculture invasive grass site as experimental controls, and two treated catchments that were recently abandoned pastures converted to teak and native species timber plantations. The catchments are found within Panama's protected Soberania National Park and the adjacent headwaters of the Agua Salud and Mendoza Rivers, all part of the greater Panama Canal Watershed. Using hydrological data from the first two and a half years of the project, three main ecosystem services are observed. The forested area exhibited lower storm event peaks, decreased flashiness, and greater stream flow during the dry season compared to the disturbed mosaic site. Lower hydrograph peaks and flashiness mitigate the risk of substantial flood damage during the major flood events generally seen in Panama between October and December. The mature forest (1.35 km2) catchment has shown lower average flood peaks in comparison to the disturbed site. For storm peaks less than 6 mm/hr, flood peaks are on average 51% lower. For storm peaks greater than 6 mm/hr, flood peaks are approximately 40% lower. In 1998, draft restrictions were imposed in the Panama Canal because of a deficit of dry season water after an El Niño-Southern Oscillation resulted in decreased wet season rainfall. The water that is available during the end of the dry season has the potential to insure the full operation of the Canal during El Niño drought years. Toward the end of the dry season (March through May) our data shows that roughly 34% more water was available during a relatively dry year with respect to antecedent wet season rainfall

  12. The anthropic catchment-ecosystem concept: an Irish example

    SciTech Connect

    Phillips-Howard, K.D.

    1985-06-01

    The catchment-ecosystem concept is adapted to investigate the nutrient-budget of the highly-modified Colebrooke drainage basin in Northern Ireland. Anthropogenic inputs, mainly manures and fertilizers, account for 86% of the nitrogen and 96% of the phosphorus added to the catchment. These inputs greatly exceed the streamflow outputs, thereby indicating that the flow of nutrients is dominated by agriculture. This is explained by the transformation of traditional mixed farming into more intensive livestock production and is linked to policies encouraging increased agricultural production, amalgamation of farms, afforestation, rural depopulation, and urbanization. Substantial increases in the N and P output of the catchment and further eutrophication of the recipient lake, Lough Erne, are predicted without the implementation of policies to reduce agricultural nutrient losses.

  13. Physical indicators of hydrologic permanence in forested headwater streams

    EPA Science Inventory

    Recent court cases have brought headwater streams and their hydrologic permanence into the forefront for regulatory agencies, so rapid field-based indicators of hydrologic permanence in streams are critically needed. Our study objectives were to 1) identify environmental charact...

  14. SCIENCE TO INFORM POLICY ON PROTECTION OF HEADWATER STREAMS

    EPA Science Inventory

    Recent court cases concerning the definition of jurisdictional waters under the Clean Water Act have illuminated a need to better understand characteristics and functions of headwater streams (and associated riparian and wetland habitats). Research is needed to better quantify 1...

  15. BIOLOGICAL INTEGRITY IN MID-ATLANTIC COASTAL PLAINS HEADWATER STREAMS

    EPA Science Inventory

    The objective of this study was to assess the applicability of landscape metrics, in conjunction with stream water quality to estimate the biological integrity of headwater streams in the Mid-Atlantic Coastal Plains using multivariate techniques.

  16. Hydro-Biogeochemical Approaches to Understanding of Water Cycling in the Gwangneung Coniferous Catchment, South Korea

    NASA Astrophysics Data System (ADS)

    Kim, S.; Choi, H.; Lim, J.

    2012-12-01

    The spatial and temporal sources of headwater catchment runoff are important factors in our understanding of the dominant controls on catchment runoff. The information on flowpath, storage, residence time, and interactions of water and materials transport in a catchment is the prerequisite to the understanding and predicting of water cycling in the mountainous landscapes. In this presentation, along with some up-to-date results of hydro-biogeochemical researches, we present the principal methods that are currently used in Forest Water Resources Laboratory, Korea Forest Research Institute to obtain such information. Various catchment hydrological processes have been examined on the basis of the water table fluctuations, the end-member mixing model, the cross correlation analysis, and stable isotope. The stream discharge from the surface and shallow soil layer momentarily dominated at peak flow, and then its relative contribution decreased as precipitation intensity declined. Such a pattern (though with a greater magnitude) is consistent with those reported in many mixing-model studies of forested catchments. Overall surface discharge, on the other hand, steadily increased with subsequent storm events throughout the season. The previous study suggested that maintained precipitation expands saturation zone and increases macropore flow in the forested catchment. Such a macropore flow delivers new water in which dissolved ion concentrations are low because of short contact time with soil and bedrock. In the Gwangneung coniferous forest catchment, the contribution of surface discharge was relatively large, and the changes in the amount, intensity and patterns of precipitation affected both the flowpath and the mean residence time of water. Particularly during the summer monsoon, changes in precipitation patterns and hydrological processes in the catchment influenced the carbon cycle such that the persistent precipitation increased the discharge of dissolved organic

  17. Upland disturbance affects headwater stream nutrients and suspended sediments during baseflow and stormflow

    USGS Publications Warehouse

    Houser, J.N.; Mulholland, P.J.; Maloney, K.O.

    2006-01-01

    Because catchment characteristics determine sediment and nutrient inputs to streams, upland disturbance can affect stream chemistry. Catchments at the Fort Benning Military Installation (near Columbus, Georgia) experience a range of upland disturbance intensities due to spatial variability in the intensity of military training. We used this disturbance gradient to investigate the effects of upland soil and vegetation disturbance on stream chemistry. During baseflow, mean total suspended sediment (TSS) concentration and mean inorganic suspended sediment (ISS) concentration increased with catchment disturbance intensity (TSS: R2 = 0.7, p = 0.005, range = 4.0-10.1 mg L-1; ISS: R2 = 0.71, p = 0.004, range = 2.04-7.3 mg L-1); dissolved organic carbon (DOC) concentration (R2 = 0.79, p = 0.001, range = 1.5-4.1 mg L-1) and soluble reactive phosphorus (SRP) concentration (R2 = 0.75, p = 0.008, range = 1.9-6.2 ??g L-1) decreased with increasing disturbance intensity; and ammonia (NH 4+), nitrate (NO3-), and dissolved inorganic nitrogen (DIN) concentrations were unrelated to disturbance intensity. The increase in TSS and ISS during storms was positively correlated with disturbance (R2 = 0.78 and 0.78, p = 0.01 and 0.01, respectively); mean maximum change in SRP during storms increased with disturbance (r = 0.7, p = 0.04); and mean maximum change in NO3- during storms was marginally correlated with disturbance (r = 0.58, p = 0.06). Soil characteristics were significant predictors of baseflow DOC, SRP, and Ca 2+, but were not correlated with suspended sediment fractions, any nitrogen species, or pH. Despite the largely intact riparian zones of these headwater streams, upland soil and vegetation disturbances had clear effects on stream chemistry during baseflow and stormflow conditions. ?? ASA, CSSA, SSSA.

  18. Upland disturbance affects headwater stream nutrients and suspended sediments during baseflow and stormflow

    SciTech Connect

    Houser, Jeffrey N

    2006-01-01

    Because catchment characteristics determine sediment and nutrient inputs to streams, upland disturbance can affect stream chemistry. Catchments at the Fort Benning Military Installation (near Columbus, Georgia) experience a range of upland disturbance intensities due to spatial variability in the intensity of military training. We used this disturbance gradient to investigate the effects of upland soil and vegetation disturbance on stream chemistry. During baseflow, mean total suspended sediment (TSS) concentration and mean inorganic suspended sediment (ISS) concentration increased with catchment disturbance intensity (TSS: R 2 = 0.7, p = 0.005, range = 4.0-10.1 mg L-1; ISS: R 2 = 0.71, p = 0.004, range = 2.04-7.3 mg L-1); dissolved organic carbon (DOC) concentration (R 2 = 0.79, p = 0.001, range = 1.5-4.1 mg L-1) and soluble reactive phosphorus (SRP) concentration (R 2 = 0.75, p = 0.008, range = 1.9-6.2 {micro}g L-1) decreased with increasing disturbance intensity; and ammonia (NH4 +), nitrate (NO3 -), and dissolved inorganic nitrogen (DIN) concentrations were unrelated to disturbance intensity. The increase in TSS and ISS during storms was positively correlated with disturbance (R 2 = 0.78 and 0.78, p = 0.01 and 0.01, respectively); mean maximum change in SRP during storms increased with disturbance (r = 0.7, p = 0.04); and mean maximum change in NO3 - during storms was marginally correlated with disturbance (r = 0.58, p = 0.06). Soil characteristics were significant predictors of baseflow DOC, SRP, and Ca2+, but were not correlated with suspended sediment fractions, any nitrogen species, or pH. Despite the largely intact riparian zones of these headwater streams, upland soil and vegetation disturbances had clear effects on stream chemistry during baseflow and stormflow conditions.

  19. Ecology and management of agricultural drainage ditches: a literature review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural drainage ditches are headwater streams that have been modified or constructed for agricultural drainage, and are often used in conjunction with tile drains. These modified streams are a common landscape feature in Ohio, and constitute 25% of stream habitat within the state. Management o...

  20. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runo