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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. How agricultural landscape features control the transfer of nutrient and eutrophication risk in headwater catchments?

    NASA Astrophysics Data System (ADS)

    Dupas, Rémi; Delmas, Magalie; Dorioz, Jean-Marcel; Garnier, Josette; Moatar, Florentina; Gascuel-Odoux, Chantal

    2014-05-01

    The degradation of surface water quality due to nitrogen and phosphorus pollution is a major concern for drinking water quality and ecosystems health. Numerous studies have demonstrated that headwater catchments are large contributors of nutrient loads to downstream waters bodies. In terms of scientific understanding of the processes controlling nutrient transfers, headwater catchments are relevant spatial units to study the role of landscape features because of the relatively low contribution of point sources and in-stream processes compared to larger river networks. This paper presents an analysis of the variability in space and time of observed N and P loads for a dataset of 160 headwater catchments at a national level (France). A multivariate statistical analysis was performed to relate observed N and P loads to spatial attributes describing agricultural landscapes and the physical characteristics of the catchments: climate, topography, soils, etc. We identified factors controlling N and P loads and N:P:Si ratios in freshwaters; and specifically spatially described factors, by considering river corridors and interaction between soils and land use attributes. The same catchment dataset is used to calibrate the Nutting model, i.e. a statistical model developed to estimate nutrient emission to surface water, using readily available data in France (Dupas et al., 2013). Nutting is a statistical model linking N/P sources and catchment land and river attributes to estimate mean interannual nitrate-N, total-N, dissolved-P and total-P loads. It allows to extrapolate nutrient loads in unmonitored catchments at a national level and to estimate the risk of eutrophication in freshwaters considering Redfield's (1963) N:P:Si ratios. Results show that N is in excess over silica in 93% of French headwater bodies, and that phosphorus is in excess over silica in 26%-65% of French headwater catchments. This means that between 26% and 63% of French headwaters are at risk of

  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, T.; Gascuel-Odoux, C.; Durand, P.; Weiler, M.

    2015-08-01

    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 retention 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 as functional units which could be distinguished and ordered regarding their relative contribution to nutrient dynamics at the catchment outlet. Based on synoptic 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 analyzing the spatio-temporal in-stream retention processes and their effect on the spatio-temporal fluxes of nitrates from sub-catchments. Thereby, we have been able to distinguish between nitrate sinks and sources per stream reaches and sub-catchments. For nitrate sources we have determined their permanent and temporally impact on stream water quality and for nitrate sinks we have found increasing nitrate removal efficiencies from up- 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 resources management.

  6. 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.

  7. 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

  8. Hydrologic controls on the export dynamics of dissolved and particulate phosphorus in a lowland, headwater agricultural catchment

    NASA Astrophysics Data System (ADS)

    Dupas, Rémi; Grimaldi, Catherine; Gruau, Gérard; Gascuel-Odoux, Chantal

    2014-05-01

    Phosphorus (P) availability controls eutrophication in freshwater ecosystems, since P is generally the limiting nutrient to algal development. The contribution of diffuse P emission to surface waters is significant in intensively livestock farmed catchments as a result of high application rates of P-rich animal waste and subsequent enrichment of soils. This study investigates the transport dynamics of particulate phosphorus (PP), suspended sediments (SS), and dissolved phosphorus (DP) with the aim of elucidating the relationship between PP and DP transport mechanisms and water dynamics in lowland, headwater catchments. The selected catchment (Kervidy-Naizin catchment, France) is particularly suitable for this purpose as it benefits of a 5 years, high-frequency monitoring of PP and DP concentrations at its outlet, including data recovered both during base flow and storm periods, with the monitoring of more than 50 storm flow events. The data analysis includes interpretation of concentration-discharge relationships at the annual time scale and on an event basis, seasonal analysis of flood characteristics and empirical modeling. Annual DP and PP concentration-discharge relationships of interflood samples display a hysteretic pattern, with higher concentrations during the autumn and spring periods, and progressive decrease during winter. No hysteretic pattern is visible for interflood SS concentration, which follows a classical C=a*Qb relationship. During floods, the dynamic of PP export is similar to that of SS during most of the events: the concentration peak occurs during the rising limb of the hydrogram (clockwise hysteresis), suggesting a source close to or within the stream. The amplitude and the hysteresis' loop size for SS and PP are a function of maximum discharge and rate of change in discharge. On the contrary, there is a strong decoupling between DP and SS (and thus PP) during most of the floods (no significant correlation), with DP concentration peaks

  9. 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...

  10. The seasonal dynamics of the stream sources and input flow paths of water and nitrogen of an Austrian headwater agricultural catchment.

    PubMed

    Exner-Kittridge, Michael; Strauss, Peter; Blöschl, Günter; Eder, Alexander; Saracevic, Ernis; Zessner, Matthias

    2016-01-15

    Our study examines the source aquifers and stream inputs of the seasonal water and nitrogen dynamics of a headwater agricultural catchment to determine the dominant driving forces for the seasonal dynamics in the surface water nitrogen loads and concentrations. We found that the alternating aquifer contributions throughout the year of the deep and shallow aquifers were the main cause for the seasonality of the nitrate concentration. The deep aquifer water typically contributed 75% of the total outlet discharge in the summer and 50% in the winter when the shallow aquifer recharges due to low crop evapotranspiration. The shallow aquifer supplied the vast majority of the nitrogen load to the stream due to the significantly higher total nitrogen concentration (11 mg-N/l) compared to the deep aquifer (0.50 mg-N/l). The main stream input pathway for the shallow aquifer nitrogen load was from the perennial tile drainages providing 60% of the total load to the stream outlet, while only providing 26% of the total flow volume. The diffuse groundwater input to the stream was the largest input to the stream (39%), but only supplied 27% to the total nitrogen load as the diffuse water was mostly composed of deep aquifer water. PMID:26562340

  11. 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

  12. Analysis of groundwater flow in mountainous, headwater catchments with permafrost

    NASA Astrophysics Data System (ADS)

    Evans, Sarah G.; Ge, Shemin; Liang, Sihai

    2015-12-01

    Headwater catchments have a direct impact on the water resources of downstream lowland regions as they supply freshwater in the form of surface runoff and discharging groundwater. Often, these mountainous catchments contain expansive permafrost that may alter the natural topographically controlled groundwater flow system. As permafrost could degrade with climate change, it is imperative to understand the effect of permafrost on groundwater flow in headwater catchments. This study characterizes groundwater flow in mountainous headwater catchments and evaluates the effect of permafrost in the context of climate change on groundwater movement using a three-dimensional, finite element, hydrogeologic model. The model is applied to a representative headwater catchment on the Qinghai-Tibet Plateau, China. Results from the model simulations indicate that groundwater contributes significantly to streams in the form of baseflow and the majority of groundwater flow is from the shallow aquifer above the permafrost, disrupting the typical topographically controlled flow pattern observed in most permafrost-free headwater catchments. Under a warming scenario where mean annual surface temperature is increased by 2°C, reducing the areal extent of permafrost in the catchment, groundwater contribution to streamflow may increase three-fold. These findings suggest that, in headwater catchments, permafrost has a large influence on groundwater flow and stream discharge. Increased annual air temperatures may increase groundwater discharge to streams, which has implications for ecosystem health and the long-term availability of water resources to downstream regions.

  13. 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 ...

  14. Runoff generation mechanism at two distinct headwater catchments - isotopic evidence

    NASA Astrophysics Data System (ADS)

    Dohnal, Michal; Votrubová, Jana; Šanda, Martin; Tesař, Miroslav; Vogel, Tomáš; Dušek, Jaromír

    2016-04-01

    Data from two headwater catchments indicate considerably different runoff formation mechanisms. The contributions of different surface and subsurface runoff mechanisms to the catchment discharge formation at these two small forested headwater catchments are studied with help of the natural isotopic signatures of the observed fluxes. The Uhlirska catchment (1.78 sq. km, Jizera Mts., Czech Republic) is situated in headwater area of Cerna Nisa stream. Deluviofluvial granitic sediments in the valley bottom areas (riparian zones/wetlands) are surrounded by gentle hillslopes with shallow soils developed on crystalline bedrock. The Liz catchment (0.99 sq. km, Bohemian Forest, Czech Republic) belongs to hillslope-type catchments without riparian zones situated in headwater area of Volynka River. The soil at Liz is developed on biotite paragneiss bedrock. Autocorrelation analysis of the measured catchment discharge rates reveals different hydrograph characteristics for each of the two catchments. Estimated autocorrelation lengths differ by an order of magnitude. Variations of oxygen-18 isotope concentrations in precipitation, groundwater and streamflow were analyzed. Several significant rainfall-runoff events at each of the two catchments were analyzed in detail. These events exhibit substantial difference in isotopic compositions of event and pre-event water, which facilitates hydrograph separation. Clockwise and counterclockwise hysteretic relationships between the stream discharge and its isotope concentration were identified. Results were confronted with the previously published concepts of the runoff formation at the catchments under study. The research was funded by the Czech Science Foundation, project No. 14-15201J.

  15. Boulder distribution in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Golly, Antonius; Turowski, Jens; Badoux, Alexandre; Hovius, Niels

    2016-04-01

    Headwater catchments are usually transport limited fluvial systems meaning that large amounts of sediments are stored in the channel over long time periods until transport capacity rises during flood events. Available sediment fractions include small, frequently mobile grains and large, rarely mobile clasts or boulders that have a number of functions in the fluvial system. Often, large clasts build channel-spanning forms, bear most of the shear stress and contribute to the channel's resistance and stability. Boulders often induce steps (key-stone hypothesis) where grain diameters determine the step height. Although the effects of single boulders are well studied in various lab and field experiments, extensive analysis of boulder distributions along channel reaches are rare due to the lack of observational data. Here, we analyze a large dataset of boulders in the Erlenbach, Switzerland, a mountain stream with a mean slope of 17%. Data on size, orientation and location have been collected for more than 350 boulders with a grain diameter greater 50cm (b-axis) along a 550m channel reach. In addition, channel geometry - long-profile and channel width - has been surveyed precisely with a total station. From the long-profile steps are identified with an automated algorithm. We find that the spatial distribution of the boulders along the study reach is not uniform but follows a clustered pattern. We compare the location of the boulders to various channel measures (local slope, average gradient, channel width) to find valuable proxies. Furthermore, we determine the appearance of the boulders with respect to the identified steps.

  16. Biotic controls on solute distribution and transport in headwater catchments

    NASA Astrophysics Data System (ADS)

    Herndon, E. M.; Dere, A. L.; Sullivan, P. L.; Norris, D.; Reynolds, B.; Brantley, S. L.

    2015-01-01

    Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of headwater catchments underlain by shale in Pennsylvania, USA (Shale Hills) and Wales, UK (Plynlimon), dissimilar concentration-discharge behaviors are best explained by contrasting landscape distributions of soil solution chemistry - especially dissolved organic carbon (DOC) - that have been established by patterns of vegetation. Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic "bioactive" behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in catchments where soil organic matter (SOM) is dominantly in lowlands (e.g., Shale Hills), bioactive elements are released to the stream early during rainfall events, whereas in catchments where SOM is dominantly in uplands (e.g., Plynlimon), bioactive elements are released later during rainfall events. The distribution of vegetation and SOM across the landscape is thus a key component for predictive models of solute transport in headwater catchments.

  17. 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, ...

  18. 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, ...

  19. Comparison of subsurface connectivity in Alpine headwater catchments

    NASA Astrophysics Data System (ADS)

    Zuecco, Giulia; Rinderer, Michael; van Meerveld, Ilja; Penna, Daniele; Borga, Marco

    2016-04-01

    Saturation at the soil-bedrock interface or the rise of shallow groundwater into more permeable soil layers results in subsurface stormflow and can lead to hillslope-stream connectivity. Despite the importance of subsurface connectivity for streamflow and streamwater chemistry, the factors controlling its spatial and temporal variability are still poorly understood. This study takes advantage of networks of spatially-distributed piezometers in five small (<14 ha) headwater catchments in the Italian Dolomites and the Swiss pre-Alps to i) quantify and compare the spatial and temporal variability of subsurface connectivity and its relation to streamflow, and ii) assess whether the differences in connectivity between the catchments are related to climatological or morphological characteristics of the catchments (e.g. the presence of a riparian zone). Shallow groundwater levels were measured for two years from spring to fall in 16 and 12 piezometers in the 14 and 3.3 ha catchments in the Italian Dolomites, and for four years from spring to fall in 7-8 piezometers in three <1 ha Swiss pre-alpine catchments. Subsurface connectivity was quantified by a graph-theory approach, considering linear connections (edges) between the piezometers (nodes). A node was considered to be connected to the stream when shallow groundwater was observed in the piezometer and it was connected by the edges to the stream. Weights were given to each piezometer based on Thiessen polygons to determine the area of the catchment that was connected to the stream. For the Swiss pre-alpine catchments the duration that nodes were connected to the stream was significantly correlated to the local and upslope site characteristics, such as the topographic wetness index, local slope and curvature. For the dolomitic catchment with the largest riparian zone, the time that nodes were connected to the stream was correlated with downslope site characteristics, such as the vertical distance to the nearest stream

  20. 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...

  1. 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.

  2. 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...

  3. 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.

  4. 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

  5. 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

  6. Implications of fish-habitat relationships for designing restoration projects within channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized headwater streams are common throughout agricultural watersheds in the Midwestern United States. Management of these streams focuses on drainage without consideration of the other ecosystem services they are capable of providing. Restoration of channelized agricultural headwater stream...

  7. 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...

  8. Carbon storage of headwater riparian zones in an agricultural landscape

    PubMed Central

    2012-01-01

    Background In agricultural regions, streamside forests have been reduced in age and extent, or removed entirely to maximize arable cropland. Restoring and reforesting such riparian zones to mature forest, particularly along headwater streams (which constitute 90% of stream network length) would both increase carbon storage and improve water quality. Age and management-related cover/condition classes of headwater stream networks can be used to rapidly inventory carbon storage and sequestration potential if carbon storage capacity of conditions classes and their relative distribution on the landscape are known. Results Based on the distribution of riparian zone cover/condition classes in sampled headwater reaches, current and potential carbon storage was extrapolated to the remainder of the North Carolina Coastal Plain stream network. Carbon stored in headwater riparian reaches is only about 40% of its potential capacity, based on 242 MgC/ha stored in sampled mature riparian forest (forest > 50 y old). The carbon deficit along 57,700 km headwater Coastal Plain streams is equivalent to about 25TgC in 30-m-wide riparian buffer zones and 50 TgC in 60-m-wide buffer zones. Conclusions Estimating carbon storage in recognizable age-and cover-related condition classes provides a rapid way to better inventory current carbon storage, estimate storage capacity, and calculate the potential for additional storage. In light of the particular importance of buffer zones in headwater reaches in agricultural landscapes in ameliorating nutrient and sediment input to streams, encouraging the restoration of riparian zones to mature forest along headwater reaches worldwide has the potential to not only improve water quality, but also simultaneously reduce atmospheric CO2. PMID:22333213

  9. 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

  10. 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...

  11. 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 ...

  12. 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.

  13. Influence of riparian habitat on aquatic macroinvertebrate community colonization within riparian zones of agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known about aquatic macroinvertebrate colonization of aquatic habitats within riparian zones of headwater streams in the Midwestern United States. Many headwater streams and their riparian habitats in this region have been modified for agricultural drainage. Riparian habitat modifications ...

  14. The use of PARAFAC components in studying headwater catchments: a stream and soil study

    NASA Astrophysics Data System (ADS)

    Dempsey, C.; Morris, D. P.; Pazzaglia, F. J.; Osburn, C. L.; Peters, S. C.

    2012-12-01

    Past research has shown that soils are capable of storing large quantities of organic matter and aquatic ecosystems provide a transport mechanism out of watersheds. Headwater streams provide the critical interface in understanding the interactions between the terrestrial and aquatic ecosystems where the organic carbon signatures are influenced by the variety of organic matter inputs. We hypothesized that land use plays a significant role in controlling watershed hydrology and organic carbon composition. This study assembles a PARAFAC model consisting of about 180 EEM's to constrain this complexity in three headwater catchments with specific land use types. For the past year, we have captured three seasonal storm events and sampled soil horizons along a catena within an old growth forest, once logged forest, and agricultural area. These watersheds are located in close proximity to each other, are underlain by the same bedrock type, and are less than 30 km2 in size. The streams were sampled in late summer, after leaf drop, and spring to assess seasonal changes in DOC composition and quality. Soil horizons were restricted to the upper 30 cm and were sampled during the summer. In most locations we combined the O/A-horizons and sampled the B-horizon separately. One site contained an E-horizon. We used the PARAFAC model to determine how each of the components changed throughout the course of storm events. In addition we assessed the biolability of DOC samples collected throughout the storm events and leached from soil horizons. Initial results show that many of the typical components we observe in streams come from soil horizons. Several soil EEM's showed fluorescence in areas not typically associated with riverine DOC. Biolabilty was highest after leaf drop and tended to drop or remain at steady state throughout the course of storm events. We hope to show how the quality and composition of DOC varies with land use in small watersheds.

  15. Peatland use and transport of particulate organic matter in boreal headwater catchments

    NASA Astrophysics Data System (ADS)

    Marttila, Hannu; Karjalainen, Satu-Maaria; Nieminen, Mika; Kløve, Bjørn

    2014-05-01

    Peatland use can cause increased transport of particulate organic matter (POM) causing deteriorated water quality and especially siltation of stream beds. Even though topic has gained major attention among stakeholders it has received only minor efforts to solve the main sources and properties of transported particles. The development of effective management practices and evaluation of purification efficiency demands understanding of the sources of particulate matter in peat dominated catchments with various land uses and hydrological conditions. The objectives of this study were: (1) to determinate physical properties of POM in headwater brooks affected by different peatland uses, and; (2) to identity the sources of transported material by using sediment fingerprinting methods. For this purpose, two headwater catchments under peat extraction and peatland forestry land uses with 8 sampling points were monitored for 2 years using time integrated suspended sediment samplers. Data was completed by gap samples from 50 other headwater locations with different upstream land uses: pristine, peatland forestry and peat extraction. For the sources analysis, disturbed topsoil, stream bed sediment, banks of ditches and brooks, algae and various vegetation types were identified as the potential sediment sources. Stable isotopes (δ13C, δ15N) and C/N ratio were analyzed to discriminate between the possible sources. Results are further scaled against different land uses, landscape elements and seasonal hydrological conditions in headwaters. This paper presents the preliminary results from a two year study aiming to show various patterns in transport of POM in boreal headwater catchments. Due to strong land-water relationship in headwaters, further information on the properties of particles is needed to assess the downstream impacts of land use.

  16. Chemical weathering and runoff chemistry in a steep headwater catchment

    NASA Astrophysics Data System (ADS)

    Anderson, Suzanne Prestrud; Dietrich, William E.

    2001-07-01

    We present here deductions about the location, rate, and mechanisms of chemical weathering in a small catchment based on a catchment-scale sprinkling experiment. In this experiment demineralized water was applied at an approximately steady rate in the CB1 catchment in the Oregon Coast Range to reach and maintain a quasi-steady discharge for a period of 4 days. Because of nearly steady flow conditions within the catchment, the contribution to solute fluxes from soil and bedrock could be partitioned. One half of the solute flux from the catchment derived from colluvial soil, and one half from weathering in bedrock. This implies more intense weathering in the thin colluvium mantling the catchment than in the thick underlying weathered bedrock. The annual solute flux from the catchment, scaled to the annual runoff from the catchment, is 32 +/- 10 t km-2 year-1, equivalent to published chemical denudation rates for nearby rivers with drainage areas 106 times greater than the experiment site. Soil waters sampled during the sprinkling experiment had steady compositions following a period of transient water flow conditions, implying steady-state chemical evolution in the soil. The waters leached organic anions from shallow depths in the soil, which solubilized aluminium and iron, indicating that podzolization is occurring in these soils. Carbonate dissolution appears to be an important source of solutes from the bedrock, despite being present as only a minor phase in the rock. Water balance suggests that the residence time of water in the catchment is about 2 months, and that typical 24 h storms displace only a fraction of the stored water. A consequence is that runoff chemistry is dominated by old water, which imposes strong limits on the variability of runoff composition.

  17. 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.

  18. 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...

  19. Hillslope versus riparian zone runoff contributions in headwater catchments: A multi-watershed comparison

    NASA Astrophysics Data System (ADS)

    McGlynn, B. L.; McGlynn, B. L.; McDonnell, J. J.; Hooper, R. P.; Shanley, J. B.; Hjerdt, K. N.; Hjerdt, K. N.

    2001-12-01

    It is often assumed that hillslope and riparian areas constitute the two most important and identifiable landscape units contributing to catchment runoff in upland humid catchments. Nevertheless, the relative amount and timing of hillslope versus riparian contributions to stormflow are poorly understood across different watersheds. We quantified the contributions of hillslopes and riparian zones to stormflow using physical, chemical, and isotopic techniques across 3 diverse ({ ~}15 ha) headwater catchments: a highly responsive steep wet watershed (Maimai, New Zealand), a moderately steep snowmelt dominated watershed (Sleepers, River, VT), and at a highly seasonal relatively low relief watershed (Panola Mt., Georgia). We monitored catchment runoff, internal hydrological response, and isotopic and solute dynamics for discrete riparian and hillslope zones within each catchment. Monitored catchment positions, including hillslope trenches at Maimai and Panola, were used to characterize directly, the hydrologic response and source water signatures for hillslope zones and riparian zones. We also examined the spatial and temporal source components of catchment stormflow using 3-component mass balance hydrograph separation techniques. At Maimai, NZ we found that hillslope runoff comprised 47-55% of total runoff during a 70 mm event. Despite the large amount of subsurface hillslope runoff in total catchment stormflow, riparian and channel zones accounted for 28% out of 29% of the total new water measured catchment runoff. Riparian water dominated the storm hydrograph composition early in the event, although hillslope water reached the catchment outlet soon after hillslope water tables were developed. Preliminary results for Sleepers River, VT and Panola Mountain, GA indicate that the timing and relative proportion of hillslope water in catchment runoff is later and smaller than at Maimai. Our multi-catchment comparison suggests that the ratio of the riparian reservoir to the

  20. Dominant mechanisms for the delivery of fine sediment and phosphorus to fluvial networks draining grassland dominated headwater catchments.

    PubMed

    Perks, M T; Owen, G J; Benskin, C McW H; Jonczyk, J; Deasy, C; Burke, S; Reaney, S M; Haygarth, P M

    2015-08-01

    Recent advances in monitoring technology have enabled high frequency, in-situ measurements of total phosphorus and total reactive phosphorus to be undertaken with high precision, whilst turbidity can provide an excellent surrogate for suspended sediment. Despite these measurements being fundamental to understanding the mechanisms and flow paths that deliver these constituents to river networks, there is a paucity of such data for headwater agricultural catchments. The aim of this paper is to deduce the dominant mechanisms for the delivery of fine sediment and phosphorus to an upland river network in the UK through characterisation of the temporal variability of hydrological fluxes, and associated soluble and particulate concentrations for the period spanning March 2012-February 2013. An assessment of the factors producing constituent hysteresis is undertaken following factor analysis (FA) on a suite of measured environmental variables representing the fluvial and wider catchment conditions prior to, and during catchment-wide hydrological events. Analysis indicates that suspended sediment is delivered to the fluvial system predominantly via rapidly responding pathways driven by event hydrology. However, evidence of complex, figure-of-eight hysteresis is observed following periods of hydrological quiescence, highlighting the importance of preparatory processes. Sediment delivery via a slow moving, probably sub-surface pathway does occur, albeit infrequently and during low magnitude events at the catchment outlet. Phosphorus is revealed to have a distinct hysteretic response to that of suspended sediment, with sub-surface pathways dominating. However, high magnitude events were observed to exhibit threshold-like behaviour, whereby activation and connection of usually disconnected depositional zones to the fluvial networks results in the movement of vast phosphorus fluxes. Multiple pathways are observed for particulate and soluble constituents, highlighting the

  1. 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

  2. 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.

  3. 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

  4. Relative importance of water chemistry and habitat to fish communities in headwater streams influenced by agricultural land use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized headwater streams are common throughout agricultural watersheds in the Midwestern United States. Understanding the relative impacts of agricultural contaminants and habitat degradation on the aquatic biota within agricultural headwater streams will provide information that can assist wi...

  5. Rapid decomposition of maize detritus in agricultural headwater streams.

    PubMed

    Griffiths, Natalie A; Tank, Jennifer L; Royer, Todd V; Rosi-Marshall, Emma J; Whiles, Matt R; Chambers, Catherine P; Frauendorf, Therese C; Evans-White, Michelle A

    2009-01-01

    Headwater streams draining agricultural landscapes receive maize leaves (Zea mays L.) via wind and surface runoff, yet the contribution of maize detritus to organic-matter processing in agricultural streams is largely unknown. We quantified decomposition and microbial respiration rates on conventional (non-Bt) and genetically engineered (Bt) maize in three low-order agricultural streams in northwestern Indiana, USA. We also examined how substrate quality and in-stream nutrient concentrations influenced microbial respiration on maize by comparing respiration on maize and red maple leaves (Acer rubrum) in three nutrient-rich agricultural streams and three low-nutrient forested streams. We found significantly higher rates of microbial respiration on maize vs. red maple leaves and higher rates in agricultural vs. forested streams. Thus both the elevated nutrient status of agricultural streams and the lability of maize detritus (e.g., low carbon-to-nitrogen ratio and low lignin content) result in a rapid incorporation of maize leaves into the aquatic microbial food web. We found that Bt maize had a faster decomposition rate than non-Bt maize, while microbial respiration rates did not differ between Bt and non-Bt maize. Decomposition rates were not negatively affected by genetic engineering, perhaps because the Bt toxin does not adversely affect the aquatic microbial assemblage involved in maize decomposition. Additionally, shredding caddisflies, which are known to have suppressed growth rates when fed Bt maize, were depauperate in these agricultural streams, and likely did not play a major role in maize decomposition. Overall, the conversion of native vegetation to row-crop agriculture appears to have altered the quantity, quality, and predictability of allochthonous carbon inputs to headwater streams, with unexplored effects on stream ecosystem structure and function. PMID:19323178

  6. Importance of instream wood characteristics for developing restoration designs for channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized agricultural headwater streams are a common feature within agricultural watersheds of the Midwestern United States. These small streams have been impacted by the physical and chemical habitat alterations incurred to facilitate agricultural drainage. Quantitative information on the instr...

  7. Characteristics of instream wood within channelized agricultural headwater streams in the Midwestern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized agricultural headwater streams are a common feature within agricultural watersheds of the Midwestern United States. These small streams have been impacted by the physical and chemical habitat alterations incurred to facilitate agricultural drainage. Quantitative information on the instre...

  8. How microtopography and soil morphology can help decipher flow paths and processes in headwater catchments

    NASA Astrophysics Data System (ADS)

    Gannon, J. P.; McGuire, K. J.; Bailey, S.

    2012-12-01

    Headwater catchments dominate the drainage basins of larger rivers and determine the water quality of downstream water bodies. In these catchments, hydrology strongly influences soil development and soil chemistry, thereby determining stream water quality. This study aims to explain spatial and temporal variations of flow paths and fine scale variations in hydrologic regimes at the headwater catchment scale utilizing a hydropedological approach. Hydropedologic units (HPUs), defined by differing soil morphological characteristics provide a framework for describing the function of different soil types in a catchment. Preliminary analysis and field observations also indicate that HPU locations will be predictable based on surface microtopography calculated from a 1-meter, LiDAR (Light Detection and Range) derived digital elevation model. We show that water table data from 50 wells distributed throughout the catchment confirms HPUs are indicative of specific hydrologic flow regimes, including threshold behavior, consistent with predictions based on soil morphology alone. This study focuses on three intensive study sites representative of typical soil morphological development in a small catchment. Furthering the water table analysis, measures of saturated and unsaturated hydrologic regimes, surface topographic characteristics, subsurface characteristics, and soil morphology were compared for the three intensive sites in an effort to quantify the effect of surface microtopography on the proposed hydropedologic system. Preliminary analysis shows matric potential gradients develop laterally down slope at site locations hypothesized to be indicative of lateral podsolization based on site topography and soil morphology. These results are in agreement with our findings describing threshold behavior in water table development at the same sites. The results of this study suggest a hydropedological approach may be a useful tool for describing catchment runoff response as well

  9. 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.

  10. 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.

  11. Streamwater mercury dynamics within three headwater catchments in Shenandoah National Park, VA

    NASA Astrophysics Data System (ADS)

    Riscassi, A.; Scanlon, T. M.

    2009-12-01

    Headwater terrestrial systems are a primary source of downstream contamination because they store large pools of mercury (Hg) in soils and sediments. This study evaluates Hg dynamics in three forested headwater catchments in the southern Appalachian region. The remote catchments are located within 100 kilometers of one another, have similar physical features (size, slope, and vegetation) but are distinct in chemical and hydrological characteristics. Starting in March 2009, we have been measuring dissolved and particle-bound Hg, DOC, UV-absorbance at 254 nm, pH, and discharge within the three catchments on a bi-weekly basis. During storm events, samples are taken at 2-hr increments with automated Isco’s retrofitted for Hg sampling. For each site we quantify fluxes of particulate and dissolved Hg and determine how/if the relationship between DOC and dissolved Hg varies during storm events. We also examine how DOC quality affects Hg transport. Ultimately, this analysis will offer insight into how the hydrology and water chemistry of a catchment affect the timing, amount, and physical fractioning of Hg transport, specifically during storm events.

  12. 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...

  13. Landscape heterogeneity drives contrasting concentration-discharge relationships in shale headwater catchments

    NASA Astrophysics Data System (ADS)

    Herndon, E. M.; Dere, A. L.; Sullivan, P. L.; Norris, D.; Reynolds, B.; Brantley, S. L.

    2015-08-01

    Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of three shale-underlain headwater catchments located in Pennsylvania, USA (the forested Shale Hills Critical Zone Observatory), and Wales, UK (the peatland-dominated Upper Hafren and forest-dominated Upper Hore catchments in the Plynlimon forest), dissimilar concentration-discharge (C-Q) behaviors are best explained by contrasting landscape distributions of soil solution chemistry - especially dissolved organic carbon (DOC) - that have been established by patterns of vegetation and soil organic matter (SOM). Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Furthermore, concentration-discharge relationships of non-chemostatic solutes changed following tree harvest in the Upper Hore catchment in Plynlimon, while no changes were observed for chemostatic solutes, underscoring the role of vegetation in regulating the concentrations of certain elements in the stream. These results indicate that differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in

  14. Assessing the Success of Regional Measures for Lowering Agricultural Nutrient Pollution in Headwater Streams.

    PubMed

    Barry, C D; Foy, R H

    2016-07-01

    Lowland waters in Northern Ireland experience elevated agricultural phosphorus (P) inputs, and in response a variety of control measures targeting farm nutrient management have been implemented. Their efficacy in lowering nitrogen (N) and P exports and improving water quality is examined in 40 headwater streams from 1990 to 2009, and to 2014 for 24 of these. Over this period manure production in the study catchments declined by 7%, but regional chemical fertilizer inputs declined by 37% for N and 79% for P, and the regional nutrient surplus was lowered by 18% for N and 49% for P. Diminished pollution by organic wastes meant that 85% of streams exhibited chemistry suitable for salmonids in 2009 compared to 40% in 1990. Flow-weighted mean concentrations (FWMCs) of nutrients declined between 1990 and 2009, and their correlations with catchment stocking rates became stronger over time. For catchments with manure inputs <16.6 kg P ha, total P and nitrate FWMCs declined from 123 ± 19 μg P L and 1.92 ± 0.5 mg N L in 1990 at rates of 2.2 ± 0.5 and 30 ± 10 μg L yr, respectively. For catchments with higher manure inputs the respective rates of decline were greater at 5.8 ± 1.0 μg P L yr and 160 ± 20 μg N L yr from 1990 concentrations of 270 ± 25 μg P L and 5.99 ± 0.4 mg N L. Although now lower, P concentrations in the more highly stocked catchments still exceed regional nutrient standards so that the identification of further factors impinging on nutrient losses is critical if such standards are to be achieved. PMID:27380082

  15. Similarities in fish-habitat relationships within channelized agricultural headwater streams in Ohio and Indiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized agricultural headwater streams are common throughout agricultural watersheds in the Midwestern United States. Understanding the fish-habitat relationships within these streams will provide information that can assist with developing restoration strategies for these degraded streams. We...

  16. Influence of watershed-scale pesticide management on channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized agricultural headwater streams are streams that have been created or modified for agricultural drainage. Elevated pesticide concentrations frequently occur within these modified streams and represent a threat to their ecological integrity. Pesticide management (i.e., use of alternative ...

  17. The role of groundwater in streamflow in a headwater catchment with sub-humid climate

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Recent studies have suggested that bedrock groundwater can exert considerable influence on streamflow in headwater catchments under humid climate. However, study of the role of bedrock groundwater is still challenged due to limited direct observation data. In this study, by utilizing observed hydrometric and hydrochemical data, we aimed at characterize the bedrock groundwater's response to rainfall at hillslope and catchment scales in a small headwater catchment with sub-humid climate. We selected Xitaizi catchment with area of 6.7 km in the earth-rock mountain region, which located in the north of Beijing, China, as study area. The catchment bedrock is mainly consist of fractured granite. Four weather stations were installed to observe the weather condition and soil volumetric water content (VWC) at depth of 10-60 cm with 10-minute interval. Five wells with depth of 10 m were drilled in two slopes to monitor the bedrock water table by pneumatic water gauge. At slope 1, the soil VWC at depth of 10-80 cm were also observed by soil moisture sensors, and surface/subsurface hillslope runoff at three different layers (0-20cm, 20-80cm, 80-300cm) was observed by three recording buckets. Field works were conducted from July 2013 to November 2014. During the period, precipitation, river, spring and groundwater were sampled nearly monthly. Water temperature, electrical conductivity (EC) and pH were measured in site with portable instruments. In addition, the precipitation, river and groundwater were also sampled intensively during two storm events. All the samples were subjected to stable isotope analysis, the samples taken monthly during the period from July 2013 to July 2014 were subjected to hydrochemistry analysis. Our results show that: (1) the bedrock groundwater is the dominant component of streamflow in the headwater catchment with sub-humid climate; (2) stream is recharged by groundwater sourcing from different mountains with different hydrochemistry characteristics

  18. Runoff and Solute Mobilisation in a Semi-arid Headwater Catchment

    NASA Astrophysics Data System (ADS)

    Hughes, J. D.; Khan, S.; Crosbie, R.; Helliwell, S.; Michalk, D.

    2006-12-01

    Runoff and solute transport processes contributing to stream flow were determined in a small headwater catchment in the eastern Murray-Darling Basin of Australia using hydrometric and tracer methods. Stream flow and electrical conductivity were monitored from two gauges draining a portion of upper catchment area (UCA), and a saline scalded area respectively. Results show that the bulk of catchment solute export, occurs via a small saline scald (< 2% of catchment area) where solutes are concentrated in the near surface zone (0-40 cm). Non-scalded areas of the catchment are likely to provide the bulk of catchment runoff, although the scalded area is a higher contributor on an areal basis. Runoff from the non-scalded area is about two orders of magnitude lower in electrical conductivity than the scalded area. This study shows that the scalded zone and non-scalded parts of the catchment can be managed separately since they are effectively de-coupled except over long time scales, and produce runoff of contrasting quality. Such differences are "averaged out" by investigations that operate at larger scales, illustrating that observations need to be conducted at a range of scales. EMMA modelling using six solutes shows that "event" or "new" water dominated the stream hydrograph from the scald. This information together with hydrometric data and soil physical properties indicate that saturated overland flow is the main form of runoff generation in both the scalded area and the UCA. Saturated areas make up a small proportion of the catchment, but are responsible for production of all run off in conditions experienced throughout the experimental period. The process of saturation and runoff bears some similarities to the VSA concept (Hewlett and Hibbert 1967).

  19. 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

  20. 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

  1. Incorporating preferential flow into a 3D model of a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Glaser, Barbara; Jackisch, Conrad; Hopp, Luisa; Pfister, Laurent; Klaus, Julian

    2016-04-01

    Preferential flow plays an important role for water flow and solute transport. The inclusion of preferential flow, for example with dual porosity or dual permeability approaches, is a common feature in transport simulations at the plot scale. But at hillslope and catchment scales, incorporation of macropore and fracture flow into distributed hydrologic 3D models is rare, often due to limited data availability for model parameterisation. In this study, we incorporated preferential flow into an existing 3D integrated surface subsurface hydrologic model (HydroGeoSphere) of a headwater region (6 ha) of the forested Weierbach catchment in western Luxembourg. Our model philosophy was a strong link between measured data and the model setup. The model setup we used previously had been parameterised and validated based on various field data. But existing macropores and fractures had not been considered in this initial model setup. The multi-criteria validation revealed a good model performance but also suggested potential for further improvement by incorporating preferential flow as additional process. In order to pursue the data driven model philosophy for the implementation of preferential flow, we analysed the results of plot scale bromide sprinkling and infiltration experiments carried out in the vicinity of the Weierbach catchment. Three 1 sqm plots were sprinkled for one hour and excavated one day later for bromide depth profile sampling. We simulated these sprinkling experiments at the soil column scale, using the parameterisation of the base headwater model extended by a second permeability domain. Representing the bromide depth profiles was successful without changing this initial parameterisation. Moreover, to explain the variability between the three bromide depth profiles it was sufficient to adapt the dual permeability properties, indicating the spatial heterogeneity of preferential flow. Subsequently, we incorporated the dual permeability simulation in the

  2. Controls on variability in surface and ground waters in a headwater catchment

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary; Srinivasan, MS

    2014-05-01

    Hydrologists recognise the importance of vertical drainage and deep flow paths in runoff generation, even in headwater catchments. Therefore, characterisation of the joint surfacewater-groundwater system is needed to improve hydrological understanding and model representation. 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 spatial variation in unsaturated and saturated-zone responses. Over a period of 16 months we measured continuous soil moisture at 32 locations and near-surface water table (< 2 m) at 14 locations, with varied aspects, hillslope position and distance from stream, as well as recording streamflow at 3 gauges. In this presentation we describe the controls, types and implications of variability. Our results showed several distinct causes of variability in water stores. Some types of variability involve a response of only part of the catchment to a rainfall event, e.g. partial response of deep soils in the summer months. Other types of variability involve differences in dynamics, e.g. recession shapes; or differences in response rates in different parts of the catchment, e.g. timing of winter wet-up, and a distinctive split between slow and fast groundwater responses. A further type of variability occurs when some parts of the catchment respond more strongly than others, as in the partial saturation responses seen in winter. Soil moisture and water table show different variability characteristics. Soil moisture on the North facing slope is qualitatively different to that on the South facing slope: it does not have the long winter plateau seen on the South facing slope. Groundwater variability appears to be more location specific, with both North and South facing slopes showing a combination of fast and slow water table responses to rainfall events. The many

  3. 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

  4. 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

  5. Controls on Mercury Transport from Forested Headwater Catchments in Shenandoah National Park and Beyond

    NASA Astrophysics Data System (ADS)

    Scanlon, T. M.; Riscassi, A.

    2012-12-01

    Mercury is exported from forested watersheds primarily during storms events, the consequence of hydrological transport through shallow subsurface and surface pathways and the mobilization of in-stream sediment. Our sampling efforts focused on high-flow events within three forested headwater catchments in Shenandoah National Park over the course of a full year using an automated sampling procedure. The dissolved and particulate forms of mercury exhibit distinct transport characteristics, with the former influenced primarily by dissolved organic carbon quantity and quality and the latter driven by suspended sediment concentrations, with more pronounced hysteresis. The amount of mercury export from the three forested catchments is compared with estimates from other systems, as is the "enrichment" factor of dissolved mercury per unit dissolved organic carbon. We speculate as to why this enrichment factor tends to be higher for systems with smaller pools of soil organic matter. Distributed measurements of soil mercury concentrations within a catchment show that elevation also plays a role in influencing the amount of mercury stored within the organic soil horizon. Continued efforts to quantify dry deposition are also presented, which has implications for better constraining the mercury budgets of forested catchments.

  6. 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

  7. 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...

  8. 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

  9. 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...

  10. 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...

  11. 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

  12. A Model Based Attribution of Streamflow Trends in Headwater Catchments of the Tarim River, Central Asia

    NASA Astrophysics Data System (ADS)

    Duethmann, D.; Bolch, T.; Pieczonka, T.; Farinotti, D.; Tong, J.; Guntner, A.

    2014-12-01

    Over the last decades, increasing streamflow has been observed in glacierized headwater catchments of the Tarim River, Central Asia. We investigated to what extent these streamflow increases can be attributed to increasing precipitation, or increasing air temperature and resulting glacier mass loss, using a data-driven approach based on multiple linear regression, and a simulation-driven approach with a hydrological model. The hydrological model was calibrated in a multi-objective way using criteria for discharge and glacier mass balances. This is crucial in such catchments with high uncertainties in precipitation, as a deficient streamflow simulation due to inadequate precipitation input may be compensated by erroneous simulation of glacier melt, if both variables are not jointly considered for model calibration. Temporal variations in glacier changes were calibrated against an observed glacier mass balance time series, whilst geodetic glacier mass balance estimates were used for constraining the absolute mass balance loss. The model considers the effects of changes in glacier area and in the elevation of the glacier surface over the course of the 48-years study period. Simulations with detrended time series indicate that changes in the less glacierized Kokshaal catchment are caused by increases in precipitation and glacier melt to a comparable extent. In contrast, for the more highly glacierized Sary-Djaz catchment, increasing glacier melt plays a dominant role. Results from the data-based approach were generally comparable, but pointed to a higher influence of temperature also in the Kokshaal catchment. Overall, the hydrological modeling approach was considered as advantageous because it allows to (1) directly investigate cause-effect relations, (2) analyze the impact of changes in variables that are not measured (e.g., changes in the fraction of glacier melt), and (3) integrate different kinds of data (like glacier mass balances or snow cover data). In this way

  13. 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

  14. Spatial Distribution of Acid Neutralizing Processes in Steep Headwater Catchments in Tanakami Mountains, Central Japan

    NASA Astrophysics Data System (ADS)

    Asano, Y.; Uchida, T.; Ohte, N.; Tani, M.

    2001-05-01

    The areas characterized by steep slope, thin soils, and unreactive bedrock types are often considered as acid-sensitive. The purpose of this study is to investigate the spatial distribution of acid neutralizing processes in steep headwater catchment in the humid temperate region, and to discuss the long-term change in acid neutralizing processes associated with the forest growth and soil development. The observations were conducted at two adjacent unchannelled steep catchment, Fudoji (0.10ha) and Rachidani (0.18ha). Two catchments share similar climatic condition and the same bedrock geology (granite). The mean hollow gradient is 37degrees in Fudoji and 34degrees in Rachidani. Fudoji is forested with mean soil depth of 77cm, while Rachidani is non-vegetated with mean soil depth of about 10cm. In both catchments, hydrometric and isotopic measurements illustrated the substantial downward water flux into the bedrock in upslope area and emerging of this water from bedrock to soil layer within 2m from the perennial spring points. The mean pH of soil water and groundwater were dispersed over a wide range of 4.00 to 5.84 in Fudoji and 5.29 to 6.28 in Rachidani, while stream pHs converged very closely to neutral value in two catchments. In both catchments, major H+ sources distributed at the near-surface soil layer and the intensity of internal H+ production was greater in forested Fudoji than non-vegetated Rachidani, attributed to the biological cycles in forest ecosystems. Calculation of budget for base cations (Na+, K+, Ca2+ and Mg2+) presented that 72 to 84 percent (Fudoji) and 34percent (Rachidani) of the net base cation production in each catchment was derived from the bedrock, indicating that a considerable amount of the H+ was consumed within the bedrock. Moreover, the H+ consumption rate per unit volume of soil in Fudoji was almost one order of magnitude smaller than that of Rachidani. These results suggested that the dominant H+ sink in catchments shifted from

  15. Potentials and constraints of different types of soil moisture observations for flood simulations in headwater catchments

    NASA Astrophysics Data System (ADS)

    Bronstert, A.; Creutzfeldt, B.; Graeff, T.; Hajnsek, I.; Heistermann, M.; Itzerott, S.; Jagdhuber, T.; Kneis, D.; Lück, E.; Reusser, D.; Zehe, E.

    2012-04-01

    Flood generation in mountainous headwater catchments is governed by rainfall intensities, by the spatial distribution of rainfall and by the state of the catchment prior to the rainfall, e.g. by the spatial pattern of the soil moisture, groundwater conditions, and possibly snow. The work presented here explores the limits and potentials of measuring soil moisture with different methods and in different scales and their potential use for flood simulation. These measurements were obtained in 2007 and 2008 within a comprehensive multi-scale experiment in the Weisseritz headwater catchment in the Ore-Mountains, Germany. The following technologies have been applied jointly thermogravimetric method, Frequency Domain Reflectometry (FDR) sensors, Spatial-Time Domain Reflectometry (STDR) cluster, Ground Penetrating Radar (GPR), airborne polarimetric synthetic aperture radar (polarimetric-SAR) and Advanced Synthetic Aperture Radar (ASAR) based on the satellite Envisat. We present exemplary soil measurement results, with spatial scales ranging from point scale, via hillslope and field scale to the catchment scale. Only the Spatial-TDR cluster was able to record continuous data. The other methods are limited to the date of over flights (airplane and satellite) or measurement campaigns on the ground. At a first glance, using soil moisture data to initiate better flood modelling (including flood forecasts) seems to be a rather straight forward approach. However, this approach bears several problems regarding the operational use of such data and the model parameterisation: 1) A main constraint is that the observation of spatially distributed soil moisture and the subsequent data processing are still far from an operational stage because continuous or quasi-continuous air-borne observation and processing of soil moisture is not available; 2) remote soil moisture sensors observe only a quite shallow soil depths, which are of restricted relevance for flood generation and water

  16. 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

  17. 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.

  18. Using high-resolution phosphorus data to investigate mitigation measures in headwater river catchments

    NASA Astrophysics Data System (ADS)

    Campbell, J. M.; Jordan, P.; Arnscheidt, J.

    2015-01-01

    This study reports the use of high-resolution water quality monitoring to assess the influence of changes in land use management on total phosphorus (TP) transfers in two 5 km2 agricultural sub-catchments. Specifically, the work investigates the issue of agricultural soil P management and subsequent diffuse transfers at high river flows over a 5-year timescale. The work also investigates the phenomenon of low flow P pollution from septic tank systems (STSs) and mitigation efforts - a key concern for catchment management. Results showed an inconsistent response to soil P management over 5 years with one catchment showing a convergence to optimum P concentrations and the other an overall increase. Both catchments indicated an overall increase in P concentration in defined high flow ranges. Low flow P concentration showed little change or higher P concentrations in defined low flow ranges despite replacement of defective systems and this is possibly due to a number of confounding reasons including increased housing densities due to new-builds. The work indicates fractured responses to catchment management advice and mitigation and that the short to medium term may be an insufficient time to expect the full implementation of policies (here defined as convergence to optimum soil P concentration and mitigation of STSs) and also to gauge their effectiveness.

  19. Using high-resolution phosphorus data to investigate mitigation measures in headwater river catchments

    NASA Astrophysics Data System (ADS)

    Campbell, J. M.; Jordan, P.; Arnscheidt, J.

    2014-09-01

    This study reports the use of high resolution water quality monitoring to assess the influence of changes in landuse management on total phosphorus (TP) transfers in two 5 km2 agricultural sub-catchments. Specifically, the work investigates the "wicked problem" of agricultural soil P management and subsequent diffuse transfers at high river flows over a five year timescale. The work also investigates the phenomenon of low flow P pollution from septic tank systems (STS) and mitigation efforts - here termed the "filthy issue" of rural catchment management. Results showed an inconsistent response to soil P management over five years with one catchment showing a convergence to optimum P concentrations and the other an overall increase. Both catchments indicated an overall increase in P concentration in defined high flow ranges. Low flow P concentration showed little change or higher P concentrations in defined low flow ranges despite replacement of defective systems and this is possibly due to a number of confounding reasons including increased housing densities due to new-builds. The work indicates fractured responses to catchment management advice and mitigation and that the short to medium term may be an insufficient time to expect the full implementation of policies (here defined as convergence to optimum soil P concentration and mitigation of STS) and also to gauge their effectiveness.

  20. 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

  1. 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.

  2. 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

  3. Understanding soil phosphorus systems from emergent phosphorus behaviour in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Ockenden, Mary; Beven, Keith; Collins, Adrian; Evans, Bob; Falloon, Pete; Hiscock, Kevin; Hollaway, Michael; Kahana, Ron; Macleod, Kit; Ross, Kirsty; Wearing, Catherine; Withers, Paul; Zhou, Jian; Benskin, Clare; Burke, Sean; EdenDTC Team; Haygarth, Phil

    2015-04-01

    Knowledge of soil phosphorus (P) sources and pathways is essential for predicting P transfers to water in the future, when drivers of P biogeochemistry may change under climate and land use change. However, the understanding of high frequency phosphorus dynamics has been limited by data of insufficient temporal resolution. This study shows how observing the patterns shown by headwater catchment systems can help to improve understanding of soil system science. The study describes analysis of 15 minute resolution data of rainfall and river discharge, and 30 minute resolution data of total phosphorus (TP) and total reactive phosphorus (TRP) concentrations from a sub-basin of the River Eden catchment, Cumbria, UK, collected by the Defra Demonstration Test Catchment Programme. The analysis focussed on extreme events and event sequences, which are predicted to occur more frequently under a changing climate, such as periods of drying followed by heavy rainfall. Events were classified according to exceedance of discharge and P concentration thresholds (Type 1 = high discharge, low TP; Type 2 = high discharge, high TP; Type 3 = low discharge, high TP). More than 75% of the TP load was transported during the 5% of the time with highest river discharge, with more than 69% of the TP load transferred in Type 2 events (< 4% in Type 1 events). High phosphorus concentrations in the river were also recorded during rainfall events following a dry period, when there was little response in discharge (Type 3, which accounted for less than 2% of total load). A lag of around one hour between peak TP and peak TRP concentrations indicated different pathways, with TP influenced by quickly mobilised sources, such as a readily available soil P pool, and fast pathways. In contrast, TRP showed a slower response indicating the presence of slower sub-surface pathways. Improved understanding of these processes will help in understanding the importance and availability of soil P pools in order to

  4. Stream and bed temperature response to partial-retention forest harvesting in a coastal headwater catchment

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    This study quantified the effects of partial-retention forest harvesting on stream and bed temperatures in a headwater catchment in coastal British Columbia, Canada. Stream temperature was recorded between 2002 and 2005 at four sites, three located within the harvested area and one upstream. Logging occurred in autumn 2004. Shallow groundwater temperatures, along with bed temperature profiles at depths of 1 to 30 cm, were recorded at 10-minute intervals in two hydrologically distinct reaches beginning in 2003 or 2004, depending on the site. The lower reach had smaller discharge contributions via lateral inflow from the hillslopes and fewer areas with upwelling and/or neutral flow across the stream bed compared to the middle reach. Based on a paired-catchment analysis, the logging treatment resulted in higher daily maximum stream and bed temperatures but smaller changes in daily minima. Changes in daily maximum stream temperature, averaged over July and August of the post-harvest year, ranged from 1.6 to 3 oC at different locations within the cut block. Post-harvest changes in bed temperature in the lower reach were lower than the changes in stream temperature, greater at sites with downwelling flow, and decreased with depth at both upwelling and downwelling sites, dropping to about 1 oC at a depth of 30 cm. In the middle reach, changes in daily maximum bed temperature, averaged over July and August, were generally about 1 oC and did not vary significantly with depth. The pre-harvest regression models for shallow groundwater were not suitable for applying the paired-catchment analysis to estimate the effects of harvesting.

  5. Influence of herbaceous riparian buffers on physical habitat, water chemistry, and stream communities within channelized agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbaceous riparian buffers are a widely used agricultural conservation practice in the United States for reducing nutrient, pesticide, and sediment loadings in agricultural streams. The ecological impacts of herbaceous riparian buffers on the channelized agricultural headwater streams that are comm...

  6. Hillslopes to hollows to first order channels: identification of transitions and characteristics of process domains in headwater catchments

    NASA Astrophysics Data System (ADS)

    Williams, K.; Locke, W. W.

    2009-12-01

    Where hillslopes end and hollows and first order channels begin continues to be a relevant question for landscape evolution and development of channel networks. In this work, we test a technique using LIDAR-derived topographic indices to define the transition from hillslopes to unchannelized (zero order) hollows, and from hollows to first order channels in four small (<4 km2 ) headwater catchments in mountainous regions of central and southwest Montana. Commonly used channel network delineation methods rely on global criteria such as area and slope thresholds, and can yield widely varying drainage patterns and density outcomes. Local curvature and an aspect-derived parameter were used to identify the spatial extent of hillslopes, hollows, and first order channels in ArcMap. The spatial patterns of frequency-magnitude plots of the local parameters were used to identify thresholds or transition zones between process domains, and indicate the degree of self-organization. Analytically-derived thresholds were verified against field mapping of channel heads and hollows. Results show that the power law portions of the frequency-magnitude relationships were successfully used to locate domain transitions. The transition zones of hillslope to hollow and hollow to channel were identified, for continuous and discontinuous headwater channels of 0.5 to 1 meter in width. Incisive flow alternates downstream with diffusive flow resulting in a discontinuous headwater channel network. The degree of network evolution and self organization of the networks was also evaluated using frequency-magnitude relationships of the topographic indices and total energy dissipation of each catchment. The southwest Montana catchments exhibited more advanced landscape evolution based upon the extent of self organization and optimality, as evidenced by minimum total catchment energy dissipation. The network development of the central Montana catchments appears constrained by debris flow lag deposit in

  7. 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.

  8. 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...

  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. The role of land use and soils in regulating water flow in small headwater catchments of the Andes

    NASA Astrophysics Data System (ADS)

    Roa-GarcíA, M. C.; Brown, S.; Schreier, H.; Lavkulich, L. M.

    2011-05-01

    Land use changes can have a significant impact on the terrestrial component of the water cycle. This study provides a comparison of three small headwater catchments in the Andean mountains of Colombia with different composition of land use. Several methods were used to quantify differences in the hydrological behavior of these catchments such as flow duration curves, stormflow analysis, and the linear reservoir concept. They were combined with an analysis of the characteristics of soils that contribute to understanding the aggregate catchment hydrological behavior. Andisols, which are soils formed in volcanic areas and with a large capacity to hold water, amplify differences in land use and limit the potential impact of land use management activities (conservation or restoration) on the water regulation function of catchments. Of the three studied catchments, less variability of flows was observed from the catchment with a larger percentage of area in forest, and a slower decrease of flows in the dry season was observed for the catchment with a relatively higher percentage of area in wetlands. Evidence is provided for the infiltration trade-off hypothesis for tropical environments, which states that after forest removal, soil infiltration rates are smaller and the water losses through quick flow are larger than the gains by reduced evapotranspiration; this is compatible with the results of the application of the linear reservoir concept showing a faster release of water for the least forested catchment.

  11. Terrestrial and in-stream influences on the spatial variability of nitrate in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Scanlon, Todd M.; Ingram, Spencer M.; Riscassi, Ami L.

    2010-06-01

    A vast majority of monitoring programs designed to assess nutrient fluxes from headwater systems rely upon temporally intensive sampling at a single position within the stream network, essentially measuring the integrated response of the catchment. Missing from such an approach is spatial information related to how nutrient availability varies throughout the network, where freshwater biota live and where biogeochemical processes ultimately shape the downstream water chemistry. Here, we examine the spatial distribution of nitrate (NO3-) concentrations within the Paine Run catchment, a forested headwater catchment in Shenandoah National Park, Virginia. Nitrate concentrations throughout the stream network were measured as part of synoptic surveys conducted in 1992-1994, in the aftermath of region-wide gypsy moth defoliation that caused dramatic increases in stream water NO3- concentrations. A follow-up synoptic survey was conducted in 2007, when the stream water NO3- concentrations had returned to predefoliation levels. Common to each of the eight synoptic surveys were observations of multiple-fold declines in NO3- concentration along the main stem of the stream network from the headwaters to the catchment outlet. A portion of this decline was caused by dilution, as water input by tributaries at the lower elevations of the catchment tended to have lower NO3- concentrations. A stream network model was applied to determine the relative contributions of terrestrial versus in-stream processes to the spatial variability of the NO3- concentrations. Model results suggest that even though nitrate removal within the stream network can be substantial, terrestrial factors that determine the NO3- inputs to streams account for the vast majority of the spatial variability in stream water NO3- concentrations.

  12. Importance of vegetation, topography and flow paths for water transit times of base flow in alpine headwater catchments

    NASA Astrophysics Data System (ADS)

    Mueller, M. H.; Weingartner, R.; Alewell, C.

    2013-04-01

    The mean transit time (MTT) of water in a catchment gives information about storage, flow paths, sources of water and thus also about retention and release of solutes in a catchment. To our knowledge there are only a few catchment studies on the influence of vegetation cover changes on base flow MTTs. The main changes in vegetation cover in the Swiss Alps are massive shrub encroachment and forest expansion into formerly open habitats. Four small and relatively steep headwater catchments in the Swiss Alps (Ursern Valley) were investigated to relate different vegetation cover to water transit times. Time series of water stable isotopes were used to calculate MTTs. The high temporal variation of the stable isotope signals in precipitation was strongly dampened in stream base flow samples. MTTs of the four catchments were 70 to 102 weeks. The strong dampening of the stable isotope input signal as well as stream water geochemistry points to deeper flow paths and mixing of waters of different ages at the catchments' outlets. MTTs were neither related to topographic indices nor vegetation cover. The major part of the quickly infiltrating precipitation likely percolates through fractured and partially karstified deeper rock zones, which increases the control of bedrock flow paths on MTT. Snow accumulation and the timing of its melt play an important role for stable isotope dynamics during spring and early summer. We conclude that, in mountainous headwater catchments with relatively shallow soil layers, the hydrogeological and geochemical patterns (i.e. geochemistry, porosity and hydraulic conductivity of rocks) and snow dynamics influence storage, mixing and release of water in a stronger way than vegetation cover or topography do.

  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. 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.

  15. 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.

  16. 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

  17. 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...

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 where catchments have exposed or

  20. 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

  1. Relative influence of upland and lowland headwaters on the isotope hydrology and transit times of larger catchments

    NASA Astrophysics Data System (ADS)

    Tetzlaff, D.; Soulsby, C.; Hrachowitz, M.; Speed, M.

    2011-04-01

    SummaryWeekly variation of δ 18O was measured over 2 years in precipitation and river water in four relatively large catchments in north east Scotland. The River Dee (1712 km 2) is predominantly upland, with impermeable geology and hydrologically responsive soils. The headwaters of the River North Esk (732 km 2) are similar, but the lower third of the catchment is underlain by a major sandstone aquifer and is lowland (i.e. <300 m altitude) in nature. The upper 20% of the River Don catchment (1273 km 2) is upland, but the remainder is lowland with freely draining soils recharging significant groundwater reservoirs in superficial drifts. The River Ythan catchment (662 km 2) is entirely lowland and similar to the lower Don. The hydrological responsiveness of the catchments was directly related to their upland area, with the Dee and the North Esk generating the highest specific discharges during high flow events. Conversely, the Don and Ythan had more subdued hydrological regimes, but higher specific discharge under baseflows. Despite broadly similar δ 18O variation in precipitation inputs, the variability of stream waters was increasingly damped in the order Ythan > Don > North Esk > Dee. Convolution integral models were used to estimate Mean Transit Times (MTTs) for the four catchments from the isotope data. These were reasonably well-constrained at around 2 years for the Dee and 3 years for the North Esk. Estimates for the Don and Ythan were poorly constrained and therefore highly uncertain, but are both likely to exceed 10 years. MTTs in upland catchments in the Scottish Highlands are relatively short (ca. 2 months-4 years) and have been shown to be strongly correlated with soil hydrology, topographic indices and precipitation intensity. However, these relationships change in lowland areas as catchments become less surface water dominated and greater groundwater storage and deeper mixing processes result in much higher MTTs. Nevertheless, a close correlation

  2. 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

  3. Groundwater Contributions to Intermittent Streamflow in a Headwater Catchment: How do Geoclimatic Controls Influence Downstream Water Quality?

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Hydrologic connectivity of headwater catchments affects surface water yield and quality of downstream drinking water supplies. Lower Gordon Gulch, a 2.75 km2 catchment, is part of the Boulder Creek watershed - the primary drinking water supply for the city of Boulder, Colorado. We hypothesize that the geologic and climatic environment within the catchment controls the magnitude, timing, and duration of hydrologic connection between the landscape and the stream, and thus the distribution of major ions to the surface water. Specifically, bedrock patterns, vegetation type and density, and snowpack dynamics influence how precipitation inputs move from the hillslopes to the catchment outlet. Preliminary results suggest that north-facing hillslopes with steeper slopes, deeper weathering of bedrock, denser vegetation stands, and a seasonal snowpack, provide consistently greater groundwater inputs to the stream compared to the south-facing hillslopes. We believe that this is in part due to subsurface bedrock patterns forcing a dominate cross-valley gradient. Through an extensive observation network of hillslope wells, periodic stream water balance measurements, and synoptic chemistry samples, we plan to continue our assessment of the spatio-temporal connectivity dynamics throughout the seasonal dry down (late summer through winter), during which streamflow can be intermittent. Results will help to guide landuse practices of upland catchments with respect to their role in Boulder's drinking water supply.

  4. Examining responses of suspended sediment transports after intense thinning in a forested headwater catchment using nested monitoring

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We examined responses of suspended sediment (SS) transports after 50% intense thinning in a 17 ha forested headwater catchment using nested 4 to 10 ha gauging stations. Strip thinning of 13- to 45-yr Japanese cedar (Cryptomeriajaponica) and cypress (Chamaecyparisobtusa) was conducted by cable dragging to skid trails in the entire watershed including nested sub-catchments. The skid trails density varied from 0 to 134 m/ha, followed by 4 m/ha. Peak SS yields monitored by turbidity sensor at the catchment outlet was 10-folds greater after the first year of thinning by comparing the pre-thinning conditions, while these values became 2-folds in the third year after thinning. This changes of peak SS concentrations suggested that recovery of vegetation cover on disturbed soil reduced peak concentrations of SS. We also confirmed changes in SS yields and recovery using paired-catchment analysis. Integrated SS yields including periods during thinning operation from August to October, 2011 varied from 0.03 to 0.06 kg. Integrated SS yields in the catchment outlet (0.05 kg) were corresponded to 5.0 kg/ha in SS yields. Organic matter content of integrated SS samples in one sub-catchment was low (0%), while the other catchments contained 0.08 and 0.13% of organic matter. 210Pbex activity in the sub-catchment (181 Bq/kg) with low organic matter content was the highest among the other nested catchments from 36 to 59 Bq/kg. Because mean 210Pbex activity from < 10 cm soil surface depth along hillslopes transects was 124 ± 83 Bq/kg, soil surface erosion from < 10 cm depth on the soil surface can be contributed to fine sediment supplies for the sub-catchments with high 210Pbex activity. In contrast, 210Pbex activity on the skid trails was low, because soil disturbance became deep with > 10 cm. Therefore, fine sediment with low 210Pbex activity on the skid trails can be transported to the catchment outlet. These characteristics were also confirmed by 137Cs activity with various

  5. Using long time series of agricultural-derived nitrates for estimating catchment transit times

    NASA Astrophysics Data System (ADS)

    Fovet, O.; Ruiz, L.; Faucheux, M.; Molénat, J.; Sekhar, M.; Vertès, F.; Aquilina, L.; Gascuel-Odoux, C.; Durand, P.

    2015-03-01

    The estimation of water and solute transit times in catchments is crucial for predicting the response of hydrosystems to external forcings (climatic or anthropogenic). The hydrogeochemical signatures of tracers (either natural or anthropogenic) in streams have been widely used to estimate transit times in catchments as they integrate the various processes at stake. However, most of these tracers are well suited for catchments with mean transit times lower than about 4-5 years. Since the second half of the 20th century, the intensification of agriculture led to a general increase of the nitrogen load in rivers. As nitrate is mainly transported by groundwater in agricultural catchments, this signal can be used to estimate transit times greater than several years, even if nitrate is not a conservative tracer. Conceptual hydrological models can be used to estimate catchment transit times provided their consistency is demonstrated, based on their ability to simulate the stream chemical signatures at various time scales and catchment internal processes such as N storage in groundwater. The objective of this study was to assess if a conceptual lumped model was able to simulate the observed patterns of nitrogen concentration, at various time scales, from seasonal to pluriannual and thus if it was relevant to estimate the nitrogen transit times in headwater catchments. A conceptual lumped model, representing shallow groundwater flow as two parallel linear stores with double porosity, and riparian processes by a constant nitrogen removal function, was applied on two paired agricultural catchments which belong to the Research Observatory ORE AgrHys. The Global Likelihood Uncertainty Estimation (GLUE) approach was used to estimate parameter values and uncertainties. The model performance was assessed on (i) its ability to simulate the contrasted patterns of stream flow and stream nitrate concentrations at seasonal and inter-annual time scales, (ii) its ability to simulate the

  6. Contrasting controls on the phosphorus concentration of suspended particulate matter under baseflow and storm event conditions in agricultural headwater streams.

    PubMed

    Cooper, Richard J; Rawlins, Barry G; Krueger, Tobias; Lézé, Bertrand; Hiscock, Kevin M; Pedentchouk, Nikolai

    2015-11-15

    Whilst the processes involved in the cycling of dissolved phosphorus (P) in rivers have been extensively studied, less is known about the mechanisms controlling particulate P concentrations during small and large flows. This deficiency is addressed through an analysis of large numbers of suspended particulate matter (SPM) samples collected under baseflow (n=222) and storm event (n=721) conditions over a 23-month period across three agricultural headwater catchments of the River Wensum, UK. Relationships between clay mineral and metal oxyhydroxide associated elements were assessed and multiple linear regression models for the prediction of SPM P concentration under baseflow and storm event conditions were formulated. These models, which explained 71-96% of the variation in SPM P concentration, revealed a pronounced shift in P association from iron (Fe) dominated during baseflow conditions to particulate organic carbon (POC) dominated during storm events. It is hypothesised this pronounced transition in P control mechanism, which is consistent across the three study catchments, is driven by changes in SPM source area under differing hydrological conditions. In particular, changes in SPM Fe-P ratios between small and large flows suggest there are three distinct sources of SPM Fe; surface soils, subsurface sediments and streambed iron sulphide. Further examination of weekly baseflow data also revealed seasonality in the Fe-P and aluminium oxalate-dithionate (Alox-Aldi) ratios of SPM, indicating temporal variability in sediment P sorption capacity. The results presented here significantly enhance our understanding of SPM P associations with soil derived organic and inorganic fractions under different flow regimes and has implications for the mitigation of P originating from different sources in agricultural catchments. PMID:26150307

  7. Hydrological controls on denitrification in riparian zone of forested headwater catchment: Soil physical properties make difference in reduced environment

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Watanabe, Y.; Oda, T.; Osaka, K.

    2010-12-01

    Riparian zone near stream plays important roles to control the solute discharge from hillslope to stream. Supply of inorganic nitrogen as an essential nutrient of aquatic primary producers is generally regulated by hydrological and biogeochemical processes such as denitrification in this unique landscape unit in headwaters. To elucidate how the denitrification is controlled by hydrological properties of riparian groundwater aquifer, we investigated two similar scaled forested headwater catchments with different soil physical properties in Japan. The Kiryu- Matsuzawa catchment (KEW, 0.6 ha) has weathered granitic bedrock, and its soils in riparian zones are sandy, while the Fukuroyama-sawa catchment (FEW, 1.1 ha) has Tertiary sedimentary bedrock, and has clayey soils. Concentrations, δ15N and δ18O of NO3- in soil water, groundwater and streamwater were monitored during 2007 - 2009. Enrichment in δ15N-NO3- was found in the perennial groundwater bodies both in KEW and FEW, indicating active denitrification occurred (Fig 1). In the same time, however, increase in δ18O-NO3- of KEW groundwater was unclear, while that of FEW was found clearly indicating the denitrification under a closed system without significant dissolved O2 (DO) and new NO3- supply. It was also suggested that the denitrification in the KEW groundwater occurred under condition with relatively high DO, and new NO3- recharge by lateral groundwater movement. These differences were explainable by hydrological features of soils holding groundwater: The mean residence time (MRT) of the groundwater in FEW was estimated as three times longer (>1000 days) than that in KEW (<300 days). Moreover, this difference in MRT of groundwater aquifer is essentially caused by difference in the soil water retention characteristics between sandy soil in KEW and clayey soil in FEW. Those indicated the possibility that the difference of soil physical properties can be reflected strongly on inorganic nitrogen discharge from

  8. Daily anomalous high flow (DAHF) of a headwater catchment over the East River basin in South China

    NASA Astrophysics Data System (ADS)

    Chen, Ji; Niu, Jun; Sivakumar, Bellie

    2014-11-01

    This study develops a new method for analyzing the terrestrial hydrologic responses to precipitation through using level-based daily anomalous high flow (DAHF) occurrence in a catchment. The objectives of this study are twofold: (1) to explore the DAHF features over a headwater catchment; and (2) to evaluate the performance of a hydrologic model for DAHF simulation. In this study, DAHF is defined as the daily streamflow on a given day, whose deseasonalised daily streamflow is larger than a given multiplier of the standard deviation (STD) of the long-term deseasonalised streamflow series. Streamflow observations of a headwater catchment over the period of 1952-1972 (i.e., before reservoir operation) at the Longchuan station in the East River basin in South China are studied. The macro-scale Variable Infiltration Capacity (VIC) model is used for streamflow simulation in the catchment, and wavelet analysis is performed to explore the DAHF variability. The study reveals that the percentages of the number of days with the first and second levels of DAHFs are 4.2% and 1%, respectively, for the observed streamflows, while the corresponding percentages for the VIC model-simulated streamflow are 5% and 1.3%, respectively. Application of the Kolmogorov-Smirnov goodness-of-fit test indicates that these two levels of DAHFs can be described by two probability distribution functions, namely the Lognormal distribution and Generalized Extreme Value Type II distribution, respectively. The variability spectrum of the first level DAHF is basically consistent with that of antecedent precipitation, but not for the second level DAHF, as revealed by the wavelet analysis. The VIC model has better performance on the variability simulation of the first level of DAHF.

  9. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment

    NASA Astrophysics Data System (ADS)

    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida

    2013-04-01

    In semi-arid headwater catchment, it is usually admitted that stream flow comes predominantly from Hortonian overland flow (infiltration excess overland flow). Consequently, subsurface flow processes, and especially perched or shallow groundwater flow, have not been studied extensively. Here we made the assumption that perched groundwater flow could play a significant role in stream flow generation in semi-arid catchment. To test this assumption, we analyzed stream flow time series of a headwater catchment in the Tunisian Cap Bon region and quantified the flow fraction coming from groundwater discharge and that from overland flow. Furthermore, the dynamics of the perched groundwater was analyzed, by focusing on the different perched groundwater-surface interaction processes : diffuse and local infiltration, diffuse exfiltration, and direct groundwater discharge to the stream channel. This work is based on the 2.6 km² Kamech catchment (Tunisia), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Results show that even though Hortonian overland flow was the main hydrological process governing the stream flow generation, groundwater discharge contribution to the stream channel annually accounted for from 10% to 20 % depending on the year. Furthermore, at some periods, rising of groundwater table to the soil surface in bottom land areas provided evidences of the occurrence of saturation excess overland flow processes during some storm events. Reference Voltz , M. and Albergel , J., 2002. OMERE : Observatoire Méditerranéen de l'Environnement Rural et de l'Eau - Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d'Observatoire de Recherche en Environnement, Ministère de la Recherche.

  10. DOC sources and DOC transport pathways in a small headwater catchment as revealed by carbon isotope fluctuation during storm events

    NASA Astrophysics Data System (ADS)

    Lambert, T.; Pierson-Wickmann, A.-C.; Gruau, G.; Jaffrezic, A.; Petitjean, P.; Thibault, J. N.; Jeanneau, L.

    2014-06-01

    Monitoring the isotopic composition (δ13CDOC) of dissolved organic carbon (DOC) during flood events can be helpful for locating DOC sources in catchments and quantifying their relative contribution to stream DOC flux. High-resolution (< hourly basis) δ13CDOC data were obtained during six successive storm events occurring during the high-flow period in a small headwater catchment in western France. Intra-storm δ13CDOC values exhibit a marked temporal variability, with some storms showing large variations (> 2 ‰), and others yielding a very restricted range of values (< 1 ‰). Comparison of these results with previously published data shows that the range of intra-storm δ13CDOC values closely reflects the temporal and spatial variation in δ13CDOC observed in the riparian soils of this catchment during the same period. Using δ13CDOC data in conjunction with hydrometric monitoring and an end-member mixing approach (EMMA), we show that (i) > 80% of the stream DOC flux flows through the most superficial soil horizons of the riparian domain and (ii) the riparian soil DOC flux is comprised of DOC coming ultimately from both riparian and upland domains. Based on its δ13C fingerprint, we find that the upland DOC contribution decreases from ca.~30% of the stream DOC flux at the beginning of the high-flow period to < 10% later in this period. Overall, upland domains contribute significantly to stream DOC export, but act as a size-limited reservoir, whereas soils in the wetland domains act as a near-infinite reservoir. Through this study, we show that δ13CDOC provides a powerful tool for tracing DOC sources and DOC transport mechanisms in headwater catchments, having a high-resolution assessment of temporal and spatial variability.

  11. Channel and Catchment Morphology, Spatial Intermittency, and Carbon Chemistry of a Headwater Stream

    NASA Astrophysics Data System (ADS)

    O'Donnell, B.; Wondzell, S. M.; Serchan, S. P.; Haggerty, R.; Ward, A. S.; Schmadel, N. M.

    2015-12-01

    We investigated carbon dynamics in a steep, forested, headwater stream in the Cascade Mountains of western Oregon, USA. Measurements from a continuously recording pCO2 probe located near the mouth of the catchment showed that the stream was always super saturated with CO2 with respect to atmospheric concentrations, ranging from 500 ppm in mid-winter to as much as 3,500 ppm in late summer. Continuous measurements of pCO2 from a hyporheic well suggested that the hyporheic zone was a likely source of the super-saturated stream water because the hyporheic concentrations of CO2 ranged from a mid-winter low of 4,000 ppm to a late summer high of 16,000 ppm. Here, we investigate the causes for the large seasonal changes in pCO2 in the stream water. We conducted longitudinal synoptic surveys of flow and carbon chemistry over the period of baseflow recession during summer 2015. The channel is narrow and steep with occasional bedrock segments. However, debris flow deposits in the lower portions of the studied reach create wider valley floors where hyporheic exchange can capture 100% of the streamflow when discharge is very low. At the beginning of the summer when discharge was relatively high, flow was spatially continuous, but by mid-summer, stream flow became spatially discontinuous. Upwelling hyporheic water in these locations appears to be super saturated with CO2. In early summer, the amount of upwelling hyporheic water was small relative to stream discharge so that hyporheic exchange had only a modest influence on stream pCO2. Later in the summer, when discharge was much smaller relative to hyporheic exchange, we observed much greater spatial variability in CO2, which averaged 2720 ppm downstream of dry segments longer than 5 m but only averaged 980 ppm in wet segments and below shorter dry segments. Over the intervening wet segments, CO2 appears to be evaded from the stream as concentrations decreased rapidly. Also, upslope accumulated area appears to control lateral

  12. Forest management for water: a hydro-ecological modeling exercise of headwater catchments in the mixed-conifer belt of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Ray, R. L.

    2011-12-01

    Hydro-ecological modeling provides a cost-effective method for evaluating the effects of vegetation change on water cycling within a catchment. In mountain watersheds, change in forest vegetation not only has direct effects on transpiration rates, but also energy exchanges that influence patterns of snow ablation. In this study, treatment scenarios were implemented using the Regional Hydro-Ecological Simulation System (RHESSys) to estimate impacts on key elements of the hydrologic cycle affected by forest harvesting - snowpack accumulation, ablation, transpiration, and streamflow. Twelve headwater catchments (0.5 - 2.6 km2, 1460 - 2450m) in the mixed-conifer zone of the central Sierra Nevada, within the Sierra and Tahoe National Forests, were included for analysis. These research sites are part of the Sierra Nevada Adaptive Management Project (SNAMP), located in the headwaters of the American and Merced Rivers, and the Southern Sierra Critical Zone Observatory (CZO) in the Kings River basin. Two methods of forest harvesting were simulated in the study watersheds: 1) uniform canopy thinning, through reduction of Leaf Area Index (LAI) values and 2) strip-cut treatments, suggested as the best method for retaining snowpack. Results from this study compare the influence of vegetation on water cycle dynamics through the two harvesting treatments, initial vegetation densities, and individual catchment size. Model simulations for pre-treatment snow depth, soil moisture, and streamflow were validated with SNAMP and CZO in-situ measurements. Preliminary results show that a linear reduction of forest canopy reduces transpiration accordingly, but produces a non-linear increase in streamflow. Peak discharges also increased, occurring earlier in the spring and having more pronounced effects in the smaller catchments. Based on these results, harvesting thresholds required for obtaining increases in water yield are evaluated. Investigating the impact of forest management on these

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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. PMID:26470010

  18. 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.

  19. Influence of vegetation on water isotope partitioning across different northern headwater catchments

    NASA Astrophysics Data System (ADS)

    Gabor, R. S.; Tetzlaff, D.; Buttle, J. M.; Carey, S. K.; Laudon, H.; Mitchell, C. P. J.; McNamara, J. P.; Soulsby, C.

    2014-12-01

    The hydrology of high latitude catchments is sensitive to small changes in temperature, and likely to be impacted by changes in climate. Vegetation water usage can play a large role in catchment hydrologic pathways, affecting how water is stored, released, and partitioned within a landscape. Thus a better understanding of how vegetation impacts water partitioning in northern catchments can help us understand how climate change will impact high-latitude hydrology. As part of the VeWa project, five catchments were chosen between 44oN and 64oN in Europe and North America, to compare the role of vegetation in the movement of water across northern landscapes. These catchments vary in aspect as well as extent of snowpack and their vegetative landscapes include heather moorland, coniferous and deciduous forests, mixed grass, and tundra landscapes. Importantly, all the catchments have records of stable isotopes in different waters of the system. An initial comparison of the water isotopes in these catchments demonstrates variation between the catchments, with the lower latitude sites showing more fractionation suggestive of evapotranspiration. While all catchments show a depletion of heavy isotopes in the spring, the depletion is most evident in catchments with a heavier snowpack. The vegetative growing season during the summer months shows the greatest impact of evapotranspiration on isotopes, indicating that an increased summer in a warmer climate would likely alter water partitioning and storage dynamics in these regions.

  20. New insights in the use of carbon isotopes as tracers of DOC sources and water pathways in headwater catchments

    NASA Astrophysics Data System (ADS)

    Lambert, Thibault; Pierson-Wickmann, Anne-Catherine; Gruau, Gérard; Petitjean, Patrice; Thibault, Jean-Noël; Jeanneau, Laurent

    2013-04-01

    Despite the significant importance of dissolved organic carbon (DOC) in aquatics ecosystems, the processes controlling DOC delivery to stream waters at the catchment scale are still poorly understood, in particular with regards to the relative importance of riparian versus upland soils as DOC sources. In this respect, the stable carbon isotopic composition of DOC (δ13CDOC) appears to be a promising tool as different δ13CDOC values are anticipated between wetland and upland soil DOC, because of differences in soil oxygenation, soil humidity and soil organic matter degradation scheme However, care must be exercised because of the possible occurrence of seasonal variations in the δ13CDOC values of both riparian and upland DOC , and because also of the possible mixing of DOC coming from spatially distinct sources. The markedly different isotopic patterns obtained during high resolution monitoring (headwater catchment from western France illustrate this difficulty. Survey of the δ13CDOC values of the DOC during these storm events showed that the variability in intra-storm DOC isotopic composition markedly evolved through time, with some storms exhibiting strongly variable δ13CDOC values (> 2 δ units), while others showed no, or much more restricted isotopic variations. A comparison of these results with previously published data revealed that this temporal variability of intra-storm δ13CDOC values is the exact transposition of the temporal variability of δ13CDOC values that was found in the riparian soil waters of this catchment during the same period. The latter variability has been shown to arise from the combined effect of changes in the production mechanisms and ultimate sources of riparian DOC and of the lateral input in the riparian domains of an isotopically heavier DOC component coming from more upland areas. Overall, results from this study confirm

  1. 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

  2. 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

  3. 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.

  4. Hydrograph separation in headwater catchments of the Andes using water isotope composition

    NASA Astrophysics Data System (ADS)

    Roa Garcia, C.; Weiler, M.

    2009-04-01

    Water isotopes have been used in hydrology for two purposes: 1) identify the age of water when it leaves a catchment, both for baseflow and for individual storms; and 2) identify the source of water that leaves the catchment during and after a precipitation event, (e.g. whether it comes from rain or from particular water reservoirs within the catchment). This knowledge has been used to understand the interactions between precipitation and catchments and as a proxy for the capacity of a catchment to store water and regulate its flow, which is particularly relevant for water managers. This study has taken three small neighboring catchments and one sub-catchment in each of them containing a wetland, to analyze their baseflow and discharge response to rain events using TRANSEP. The objectives of this study are: 1) to compare the hydrological response of the six units to test the hypothesis that connected units of the landscape e.g. wetlands have a large influence on catchment yield; 2) to analyze the effect of land use on water yield during rain events; and 3) to analyze the effects of land use on baseflow. Results indicate that for B1, the catchment with 68% of area in forest, discharge is predominantly quickflow (70%), whereas for the other two catchments, it comes from around 50% of both the quickflow reservoir and the persistent reservoir. The big influence from wetlands is seen in two results: 1) the higher proportion of baseflow discharge for BB, the catchment with a 6% of total area in wetlands, since wetlands could be contributing to groundwater recharge; 2) the mean transit time of water in BB, 172 days compared with 97 days for B1 (the forested catchment) and 28 days for B2 (the catchment with 69% in grasslands) influenced by the longer transit time for BBW and B2W. The larger proportion of discharge coming from the slow quickflow in wetlands B2 and BB, and their mean transit times, indicate that the water stored in wetlands, despite constituting surface

  5. 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.

  6. Implications of the results of colonization experiments for designing riparian restoration projects adjacent to agricultural headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many headwater streams and their riparian habitats in the Midwestern United States have been modified for agricultural drainage. Agricultural drainage often results in reductions of physical habitat diversity, shifts from woody to herbaceous riparian vegetation, and the loss of riparian habitat. T...

  7. Mineral-organic matter associations in eroding hillslopes: findings from headwater catchments in the Southern Sierra Nevada (Invited)

    NASA Astrophysics Data System (ADS)

    Berhe, A.; Stacy, E.; McCorkle, E. P.; Johnson, D. W.; Hunsaker, C. T.; Hart, S. C.

    2013-12-01

    Mineral-organic matter (OM) associations--physical encapsulation of OM inside soil aggregates and chemical bonding and complexation of organic functional groups with soil minerals--determine the proportion of soil organic matter (SOM) that is redistributed and mineralized during and after erosional transport of sediments downhill, as well as the stability of the eroded SOM post-deposition. The susceptibility of SOM to decomposition and its stabilization mechanisms can change during and after erosion as a result of: aggregate breakdown or detachment due to kinetic energy of raindrops and/or shearing during lateral transport, and reconfiguration of mineral-OM associations through formation of new and strengthening of existing mineral-OM associations in depositional environments that are enriched in carbon (C) and reactive soil minerals. The goal of this study was to determine how concentration, nature and distribution of SOM in soil fractions vary between eroding slopes and sediments exported from eroding catchments. Free organic particles exported from eroding watersheds typically represent <30% of total carbon mobilized by erosion, compared to <20% mobilized as aggregate protected C and <30% as C complexed with Fe and Al oxides. Our results show that there is large variability in nature of exported material across eight headwater catchments that is not directly related to watershed size or climatic variability. In addition, we quantified the rate at which different OM fractions are preferentially transported and can be potentially lost through decomposition during lateral transport.

  8. 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.

  9. 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

  10. Phosphorus delivery via groundwater in agricultural river catchments

    NASA Astrophysics Data System (ADS)

    Mellander, Per-Erik; Jordan, Philip; Shore, Mairead; Melland, Alice R.

    2014-05-01

    Mitigating diffuse phosphorus (P) delivery to rivers, lakes and estuaries in the agricultural landscape is important for ecological quality management. In order to plan this management, it is useful to identify and quantify dominating P transfer pathways and their potential variation over time and space. Phosphorus is anticipated to mainly be transferred to rivers episodically via pathways on the surface and is not usually considered as a major concern in groundwater-fed waters. However, in this paper we report considerable proportions of P delivery via groundwater in two agricultural river catchments with permeable soils. We investigated the P transfer pathways and links between groundwater and surface water, as well as the implication of spatio-temporally variable P concentrations in groundwater at the hillslope scale. We present four years of P concentrations in stream water (sub-hourly) and in groundwater (monthly) of different strata in four hillslopes, as well as estimated P transfer pathways for winter periods (Oct-Jan) in two ca. 10 km2 catchments in Ireland. One catchment was dominated by arable land overlying slate bedrock and the other by grassland overlying sandstone. High temporal resolution monitoring of river discharge and P concentration allowed an estimation of total P (TP) and total reactive P (TRP) transfer pathways as well as flow pathways. In the groundwater of both catchments the 4-year average dissolved reactive P was up to 0.021 mg/l (Arable) and 0.050 mg/l (Grassland) in shallow near-stream groundwater. During the winter periods in the Arable catchment 20% of the runoff, 59% of stream TP load and 35% of stream TRP load was transferred by quick aboveground pathways while 77% of runoff, 36% of TP and 58% of TRP was transferred via delayed groundwater pathways. In the Grassland catchment 10% of the runoff, 48% of TP and 38% of TRP was transferred above ground while 86% of runoff, 46% of TP and 55% of TRP transferred via groundwater. In both

  11. Seasonal Accumulation and Depletion of Localized Sediment Stores of Four Headwater Catchments in the Sierra Nevada Mountains, California

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Seasonal turbidity patterns and event-level hysteresis analysis of turbidity verses discharge in four 1 km2 headwater catchments indicate localized in-channel sediment sources and a seasonal accumulation-depletion pattern of stream sediments. Our hypothesis is that during low-flow periods, sediment accumulates at the toe of banks and is entrained and transported downstream during high-flow events, with successive storm events depleting sediment stores. Turbidity signals were analyzed during fall rain events, early to mid-winter snow-melt events, spring snow-melt, and summer dry periods. Two catchments in the American River basin at approximately 1580 m elevation and two catchments in the Merced River basin at approximately 1760 meters elevation were used in this study. All study catchments are characterized by a Mediterranean climate with a distinct wet and dry season and are in the rain-snow transition zone, with snow making up roughly 40 to 60 percent of average annual precipitation. Turbidity events tend to be infrequent and of short duration in these basins. Seasonal patterns within the four catchments include more turbidity events associated with fall rainstorms and early to mid- winter melt events than associated with peak snow-melt. When multiple discharge events occurred in succession, the largest turbidity spike was often associated with the first event and not necessarily associated with the largest discharge event. This pattern is indicative of a seasonal depletion of localized sediment stores, with the majority of accumulated sediment being transported in the first storm, leaving less available for subsequent events. Turbidity spikes were also seen during base-flow periods when no discharge events were occurring, likely from the buildup of organic matter rather than the movement of mineral-based materials. An examination of hysteresis loops for individual storm events showed that a clockwise pattern, where turbidity peaks before discharge, was dominant

  12. Identifying critical source areas for water quality: 2. Validating the approach for phosphorus and sediment losses in grazed headwater catchments

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    SummaryPhosphorus (P) and suspended sediment (SS) can impair surface water quality. Recent work purports that the majority of loss comes from a small part of the catchment where areas of high potential for supply (source) and transport (e.g., surface runoff) overlap. However, these areas, termed critical source areas (CSAs) may also be small enough to enable the targeting of mitigation practices so that the approach is cheaper and more efficient than managing whole catchments. We aimed to determine CSAs in two headwater catchments. Firstly, we measured P fractions and SS in baseflow and stormflow in sub-catchments on the premise that CSAs were most active during stormflow. Using stormflow data we then aimed to determine the contribution to streamflow P and SS load from saturation- and infiltration-excess areas and the utility of five hydrological models to isolate transport areas which would also help define CSAs. While concentrations were greater in summer-autumn, loads were greater in winter-spring. Stormflow loads accounted for on average >60% of P and SS loss, with the largest storms accounting for >75% of stormflow load. Data collected from samplers located in infiltration-excess areas indicated that stream P and SS load during small events were dominated by infiltration-excess surface runoff, whereas larger events included more saturation-excess surface runoff. Utilising estimates of flow from five hydrological approaches for modelled storms and empirical equations for P loss from various sources (e.g., surface runoff from soil and dung), the topographic index combined with infiltration-excess areas gave the best estimate of P loads in the stream. While large events accounted for most P loss, we may not be able to manage for them since they involve most of the catchment. Furthermore, since they occurred in winter, they may have little effect on surface water quality parameters such as periphyton growth in summer. Since during small storms most saturation

  13. Projections for headwater catchments of the Tarim River reveal glacier retreat and decreasing surface water availability but uncertainties are large

    NASA Astrophysics Data System (ADS)

    Duethmann, Doris; Menz, Christoph; Jiang, Tong; Vorogushyn, Sergiy

    2016-05-01

    In the Tarim River Basin, water resources from the mountain areas play a key role due to the extremely arid climate of the lowlands. This study presents an analysis of future climate change impacts on glaciers and surface water availability for headwater catchments of the Aksu River, the most important tributary to the Tarim River. We applied a glacio-hydrological model that underwent a comprehensive multivariable and multiobjective model calibration and evaluation, based on daily and interannual discharge variations and glacier mass changes. Transient glacier geometry changes are simulated using the Δh-approach. For the ensemble-based projections, we considered three different emission scenarios, nine global climate models (GCMs) and two regional climate models, and different hydrological model parameters derived from the multiobjective calibration. The results show a decline in glacier area of ‑90% to ‑32% until 2099 (reference ∼2008) (based on the 5–95 percentile range of the ensemble). Glacier melt is anticipated to further increase or stay at a high level during the first decades of the 21st century, but then declines because of decreased glacier extents. Overall discharge in the Aksu headwaters is expected to be increased in the period 2010–2039 (reference 1971–2000), but decreased in 2070–2099. Seasonally, projections show an increase in discharge in spring and early summer throughout the 21st century. Discharge changes in mid to late summer are more variable, with increases or decreases depending on the considered period and GCM. Uncertainties are largely caused by differences between the different GCMs, with further important contributions from different emission scenarios in the second half of the 21st century. Contributions from the hydrological model parameters to the ensemble uncertainty were generally found to be small.

  14. Spatial and temporal variation of residence time and storage volume of subsurface water evaluated by multi-tracers approach in mountainous headwater catchments

    NASA Astrophysics Data System (ADS)

    Tsujimura, Maki; Yano, Shinjiro; Abe, Yutaka; Matsumoto, Takehiro; Yoshizawa, Ayumi; Watanabe, Ysuhito; Ikeda, Koichi

    2015-04-01

    Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time and stock 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 and storage volume of subsurface water in time and space at the mountainous headwaters especially with steep slope. We performed an investigation on age dating and estimation of storage volume using simple water budget model in subsurface water with tracing of hydrological flow processes in mountainous catchments underlain by granite, Paleozoic and Tertiary, Yamanashi and Tsukuba, central Japan. We conducted hydrometric measurements and sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2012 in the catchments, and CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Residence time of subsurface water ranged from 11 to 60 years in the granite catchments, from 17 to 32 years in the Paleozoic catchments, from 13 to 26 years in the Tertiary catchments, and showed a younger age during the high-flow season, whereas it showed an older age in the low-flow season. Storage volume of subsurface water was estimated to be ranging from 10 ^ 4 to 10 ^ 6 m3 in the granite catchments, from 10 ^ 5 to 10 ^ 7 m3 in the Paleozoic catchments, from 10 ^ 4 to 10 ^ 6 m3 in the Tertiary catchments. In addition, seasonal change of storage volume in the granite catchments was the highest as compared with those of the Paleozoic and the Tertiary catchments. The results suggest that dynamic change of hydrological process seems to cause a larger variation of the residence time and storage volume of subsurface water in time and space in the granite catchments, whereas higher groundwater recharge rate due to frequent fissures or cracks seems to cause larger

  15. Modelling soil erosion and associated sediment yield for small headwater catchments of the Daugava spillway valley, Latvia

    NASA Astrophysics Data System (ADS)

    Soms, Juris

    2015-04-01

    The accelerated soil erosion by water and associated fine sediment transfer in river catchments has various negative environmental as well as economic implications in many EU countries. Hence, the scientific community had recognized and ranked soil erosion among other environmental problems. Moreover, these matters might worsen in the near future in the countries of the Baltic Region, e.g. Latvia considering the predicted climate changes - more precisely, the increase in precipitation and shortening of return periods of extreme rainfall events, which in their turn will enable formation of surface runoff, erosion and increase of sediment delivery to receiving streams. Thereby it is essential to carry out studies focused on these issues in order to obtain reliable data in terms of both scientific and applied aims, e.g. environmental protection and sustainable management of soils as well as water resources. During the past decades, many of such studies of soil erosion had focused on the application of modelling techniques implemented in a GIS environment, allowing indirectly to estimate the potential soil losses and to quantify related sediment yield. According to research results published in the scientific literature, this approach currently is widely used all over the world, and most of these studies are based on the USLE model and its revised and modified versions. Considering that, the aim of this research was to estimate soil erosion rates and sediment transport under different hydro-climatic conditions in south-eastern Latvia by application of GIS-based modelling. For research purposes, empirical RUSLE model and ArcGIS software were applied, and five headwater catchments were chosen as model territories. The selected catchments with different land use are located in the Daugava spillway valley, which belongs to the upper Daugava River drainage basin. Considering lithological diversity of Quaternary deposits, a variety of soils can be identified, i.e., Stagnic

  16. Seasonal Variations of Nitrate Concentrations In Agricultural Catchments

    NASA Astrophysics Data System (ADS)

    Martin, C.; Aquilina, L.; Gascuel-Odoux, C.; Molénat, J.; Ruiz, L.

    Nitrate concentrations in streams of agricultural catchments with impervious bedrock often present an interannual variability (due to landuse changes) and a seasonal one. Usually seasonal variations are characterised by high concentrations in winter and low in summer. Some catchments may present intermediate or inverse cycles (high con- centrations in summer). Two hypothesis to explain classical variations of nitrate con- centrations in streams exist: (i) the availibility of nitrate in the soil for leaching and (ii) the temporal variations of the nitrate-rich shallow groundwater. The aim of this study is to explain the occurence of classical or inverse scheme of seasonal variations by testing these two existing hypothesis and proposing an alternative one for inverse cycles. Two catchments with different seasonal variations (KERRIEN catchment : normal cycle, and KERBERNEZ catchment : inverse cycle), located in the South Western French Brittany, were instrumented in 2001 with a set of 22 piezometers in- stalled at different depths and located along the hillslope. The water table dynamic and chemestry (nitrate, chloride, carbon, Rare Earth Elements,...) had been measured weekly during one year. The shallow groundwater of the Kerrien catchment is char- acterised by two lateral domains with a temporal stability of concentrations : the bot- tom land, constantly denitrified, and the upper domain with nitrate concentrations around 60 mg.L(-1) . The Kerbernez catchment is characterised by two vertical domains with a temporal rise of concentrations : the upper domain with nitrate concen- trations around 60 mg.L(-1) , as the Kerrien catchment, and a deeper compartment, with concentrations excedeed 100 to 120 mg.L(-1) of nitrate. On the Kerrien catchment, the classical cycle is due to the most important contribution of the shal- low groundwater in winter. The inverse cycle of the Kerbernez catchment may be due to the most important contribution of the deep compartment in

  17. 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...

  18. Spatial and temporal occurrence of preferential flow in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The highly dynamic nature of preferential flow in time and space makes it challenging to identify and analyze its occurrence at the catchment scale. Novel analysis methods using soil moisture sensor response times offer an opportunity to investigate catchment-wide controls on preferential flow. The aim of this study was to identify factors that control preferential flow occurrence based on 3-year soil moisture monitoring using a wireless sensor network in the Wüstebach catchment, Germany. At 101 locations, the sensor response times at three depths (5, 20, and 50 cm) were classified into one of four classes: (1) non-sequential preferential flow, (2) velocity-based preferential flow, (3) sequential flow, and (4) no response. A conceptual model, postulating that preferential flow in the Wüstebach catchment is dominated by differences in soil type, landscape position, and rainfall input, was proposed for hypothesis testing. To test the conceptual model, the classification results were combined with spatial and event-based data to understand and identify controlling factors. Spatial parameters consisted of hydrological, topographical, and soil physical and chemical parameters. Temporal factors included precipitation characteristics and antecedent soil moisture conditions. The conceptual model as proposed could only be partly confirmed. Event-based occurrence of preferential flow was highly affected by precipitation amount, with a nearly catchment-wide preferential response during large storm events. During intermediate events, preferential flow was controlled by small-scale heterogeneity, instead of showing catchment-wide patterns. The effect of antecedent catchment wetness on the occurrence of preferential flow was generally less profound, although a clear negative relationship was found for precipitation events with more than 25 mm. It was found that spatial occurrence of preferential flow was however governed by small-scale soil and biological features and local

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

    NASA Astrophysics Data System (ADS)

    Burns, Douglas A.; McDonnell, Jeffrey J.

    1998-03-01

    Natural variations in concentrations of 18O, D, and H 4SiO 4 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 H 4SiO 4 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 peak

  20. 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

  1. Identifying dissolved organic carbon sources at a gaged headwater catchment using FDOM sensors

    NASA Astrophysics Data System (ADS)

    Malzone, J. M.; Shanley, J. B.

    2014-12-01

    The United States Geological Survey's (USGS) W-9 gage at the headwaters of Sleepers River, Vermont has been monitored for dissolved organic carbon (DOC) concentration for more than 20 years. However, the sources of this DOC during base flow and hydrologic events remain unclear. The major objectives of this research were to identify sources of DOC during storm events and to explain the observed DOC-streamflow counterclockwise hysteresis during hydrologic events. Two main hypotheses to explain hysteresis during hydrologic events were tested: (1) distant headwater wetlands are the major DOC source, which lags behind peak flow due to travel time; and (2) the entire watershed contributes to the DOC at the gage, but the response of DOC lags behind the period when groundwater contributes most to streamflow. Sources of DOC were tracked using fluorescent dissolved organic matter (FDOM) sensors in surface water and groundwater wells. Wells were installed at four depths, 0.3, 0.6, 0.9, and 1.2 m, at four sites: a peaty low-gradient riparian area near the headwaters; a mid-hillslope area on a long hillslope mid-watershed; a near-stream area on a long hillslope mid-watershed; and a low-gradient tributary confluence area just above the gage. During storm events, FDOM and hydraulic head were measured at the nested groundwater wells. Samples for DOC analysis were also taken to determine the relationship between FDOM and DOC. Results suggest that both distant sources and the greater watershed played a role in the transport of DOC to the W-9 gage. Distant peaty sources dominated during large storms and contributed the highest surface water FDOM measurements. The peak FDOM at the gage was therefore best described as a result of transport. However, export from these distant sources terminated rapidly and did not explain continued elevated FDOM at the gage. Groundwater across the watershed exhibited hysteresis analogous to that in the stream itself, with FDOM peaking as head receded

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

    PubMed

    Williams, Mark R; Buda, Anthony R; Elliott, Herschel A; Collick, Amy S; Dell, Curtis; Kleinman, Peter J A

    2015-05-01

    Riparian seepage zones in headwater agricultural watersheds represent important sources of nitrate-nitrogen (NO-N) to surface waters, often connecting N-rich groundwater systems to streams. In this study, we examined how NO-N concentrations in seep and stream water were affected by NO-N processing along seep surface flow paths and by upslope applications of N from fertilizers and manures. The research was conducted in two headwater agricultural watersheds, FD36 (40 ha) and RS (45 ha), which are fed, in part, by a shallow fractured aquifer system possessing high (3-16 mg L) NO-N concentrations. Data from in-seep monitoring showed that NO-N concentrations generally decreased downseep (top to bottom), indicating that most seeps retained or removed a fraction of delivered NO-N (16% in FD36 and 1% in RS). Annual mean N applications in upslope fields (as determined by yearly farmer surveys) were highly correlated with seep NO-N concentrations in both watersheds (slope: 0.06; = 0.79; < 0.001). Strong positive relationships also existed between seep and stream NO-N concentrations in FD36 (slope: 1.01; = 0.79; < 0.001) and in RS (slope: 0.64; = 0.80; < 0.001), further indicating that N applications control NO-N concentrations at the watershed scale. Our findings clearly point to NO-N leaching from upslope agricultural fields as the primary driver of NO-N losses from seeps to streams in these watersheds and therefore suggest that appropriate management strategies (cover crops, limiting fall/winter nutrient applications, decision support tools) be targeted in these zones. PMID:26024271

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Scanlon, Todd M.; Raffensperger, Jeff P.; Hornberger, George M.; Clapp, Roger B.

    2000-09-01

    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.

  5. 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

  6. Connections Among Terrestrial Sources of Organic and Inorganic Carbon and Surface Waters in a Permafrost- and Wildfire-Impacted Headwater Catchment, Alaska

    NASA Astrophysics Data System (ADS)

    Wickland, K.; Koch, J. C.; Crawford, J. T.; Dornblaser, M.; Kelsey, K.; Striegl, R. G.

    2014-12-01

    High-latitude headwater catchments commonly contain permafrost soils and are subject to disturbance by wildfire. Processes governing transport of organic and inorganic carbon from headwater catchments to surface waters, and the influence of permafrost and disturbance on those processes, remain poorly characterized. We conducted a two-year field study of a headwater catchment in interior Alaska to better understand terrestrial-aquatic linkages of carbon (C) in these systems. The 4.1 km2 catchment is underlain by permafrost, and is drained by a first-order stream. Portions of the catchment burned in 2003, resulting in localized removal of organic soils and subsequent permafrost thaw. During May - September of 2010 and 2011, we sampled stream and soil pore waters throughout the catchment on a weekly to bi-weekly basis for dissolved organic carbon (DOC), specific UV absorbance (SUVA), dissolved inorganic carbon (DIC), and dissolved carbon dioxide (CO2) and methane (CH4). Stream discharge and water chemistry were measured at two locations, reflecting drainage from the upper catchment (2.6 km2) and the entire catchment. Soil pore water sampling sites located between the two stream sampling stations included unburned hillslopes with permafrost depths ranging from 0.6 m to 0.75 m, burned hillslopes with permafrost depths to 1m, and riparian wetland with permafrost > 1m depth. Seasonal, interannual, and spatial differences in delivery of C constituents to the stream were evident over the two study years. Mean seasonal C loads and flow-weighted mean C concentrations (FWMC) for each stream reach showed that DOC and CH4 increased, and DIC and CO2 decreased in the downstream direction. Comparing stream FWMC to mean concentrations in soil pore waters, we determined that stream DOC, SUVA, and CH4 at the downstream location matched closely with values measured in the riparian wetland and burned hillslope locations, whereas DIC concentration was most similar to unburned hillslopes

  7. 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

  8. Hydrological Controls on Nutrient Concentrations and Fluxes in Agricultural Catchments

    NASA Astrophysics Data System (ADS)

    Petry, J.; Soulsby, C.

    2002-12-01

    This investigation into diffuse agricultural pollution and the hydrological controls that exert a strong influence on both nutrient concentrations and fluxes, was conducted in an intensively farmed lowland catchment in north-east Scotland. The study focuses on spatial and seasonal variations in nutrient concentrations and fluxes at the catchment scale, over a 15-month period. The water quality of the 14.5 km2 Newmills Burn catchment has relatively high nutrient levels with mean concentrations of NO3-N and NH3-N at 6.09 mg/l and 0.28 mg/l respectively. Average PO4-P concentrations are 0.06 mg/l. Over short timescales nutrient concentrations and fluxes are greatest during storm events when PO4-P and NH3-N are mobilised by overland flow in riparian areas, where soils have been compacted by livestock or machinery. Delivery of deeper soil water in subsurface storm flow, facilitated by agricultural under-drainage, produces a marked increase in NO3-N (6.9 mg/l) concentrations on the hydrograph recession limb. A more detailed insight into the catchment response to storm events, and in particular the response of the hydrological pathways which provide the main sources of runoff during storm events, was gained by sampling stream water at 2-hourly intervals during 5 events. End Member Mixing Analysis (EMMA) was carried out using event specific end-member chemistries to differentiate three catchment-scale hydrological pathways (overland flow, subsurface storm flow, groundwater flow) on the basis of observed Si and NO3-N concentrations in sampled source waters. Results show that overland flow generally dominates the storm peak and provides the main flow path by which P is transferred to stream channels during storm events, whilst subsurface storm flows usually dominate the storm hydrograph volumetrically and route NO3-rich soil water to the stream. The study shows that altering hydrological pathways in a catchment can have implications for nutrient management. Whilst buffer

  9. 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

  10. Chloride sources in urban and rural headwater catchments, central New York.

    PubMed

    Gutchess, Kristina; Jin, Li; Lautz, Laura; Shaw, Stephen B; Zhou, Xiaoli; Lu, Zunli

    2016-09-15

    Road salt used as a deicing agent in winter months has become an emerging contaminant to streams and groundwater. In central New York, road salts are applied heavily during winter months. Recognizing potential sources of salinity to a river may reveal processes controlling the salinization of freshwater systems, with implications for future management practices. The Tioughnioga River, located in central New York, is a headwater of the Susquehanna River, which flows into the Chesapeake Bay. Salinity of the Tioughnioga River water has been increasing since the late 1930s. In this study, water samples were collected weekly at the East and West Branches of the Tioughnioga River from 2012 to 2014. We characterize natural and anthropogenic sources of salinity in the Tioughnioga River, using two independent approaches: (1) chloride to bromide ratios (Cl/Br) and (2) linear discriminant analysis. Ratios of Cl/Br suggest that road salt runoff influence is notable in both branches, but is more significant in the West Branch, consistent with a greater area of urban land. Linear discriminant analysis confirms the results of Cl/Br in the West Branch and further indicates presence of Appalachian Basin Brines in the East Branch, although their contribution may be volumetrically small. Longitudinal stream Cl concentration profiles indicate that sources of pollution are particularly concentrated around urban areas. Residence time of Cl in the watershed is estimated to be approximately 20 to 30years using a mixing model, suggesting that stream Cl concentrations likely will continue to rise for several decades. PMID:27183460

  11. 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

  12. Modeling glacier melt and runoff in a high-altitude headwater catchment in the Cordillera Real, Andes

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    Runoff from catchments with partial glacier cover is an integrated process of glacier melt, snowmelt, and surface and subsurface runoff of meltwater and rain from glacierized and non-glacierized areas. Additionally, inherent characteristics of the tropical Andes such as large meteorological variability, high elevation and steep slopes, hydrological effects of wetlands and lakes, and rapid glacier retreat make it difficult to model glacio-hydrological responses under changing climate. In this study, we developed a semi-distributed conceptual model applicable to partially glacierized catchments in the tropical Andes that considers all of these aspects, and we applied the model to the Huayna Potosi West headwater catchment in the Cordillera Real, Bolivia. Based on the latest 2 yr dataset of meteorological and hydrological monitoring, we showed the spatial and temporal variability of air temperature and precipitation in the region, and the dataset was used to calibrate model parameters and validate the performance of the daily runoff simulation. Variations in the simulated streamflow agreed well with the observed seasonal and temporal variations, and the result also showed that uncertainty pertaining to the spatial and temporal variations in air temperature and precipitation as well as the retarding effect of a wetland and lake strongly affected the runoff hydrograph. The simulated runoff components indicated that runoff from glacier melt occurs mainly in the initial period of the wet season, from October to early December, and in the late period of the wet season, March and April, although the runoff is relatively small in the latter period. Between these two periods in the wet season, major runoff components were estimated to be subsurface runoff in the non-glacierized area and surface runoff due to snowmelt. Given the future meteorological conditions based on the observational data and a predictive general circulation model output, the model quantified the long

  13. 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

  14. 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.

  15. Tracing crop-specific sediment sources in agricultural catchments

    NASA Astrophysics Data System (ADS)

    Blake, William H.; Ficken, Katherine J.; Taylor, Philip; Russell, Mark A.; Walling, Desmond E.

    2012-02-01

    A Compound Specific Stable Isotope (CSSI) sediment tracing approach is evaluated for the first time in an agricultural catchment setting against established geochemical fingerprinting techniques. The work demonstrates that novel CSSI techniques have the potential to provide important support for soil resource management policies and inform sediment risk assessment for the protection of aquatic habitats and water resources. Analysis of soil material from a range of crop covers in a mixed land-use agricultural catchment shows that the carbon CSSI signatures of particle-reactive fatty acids label surface agricultural soil with distinct crop-specific signatures, thus permitting sediment eroded from each land-cover to be tracked downstream. High resolution sediment sampling during a storm event and analysis for CSSI and conventional geochemical fingerprints elucidated temporal patterns of sediment mobilisation under different crop regimes and the specific contribution that each crop type makes to downstream sediment load. Pasture sources (65% of the catchment area) dominated the sediment load but areal yield (0.13 ± 0.02 t ha - 1 ) was considerably less than that for winter wheat (0.44 ± 0.15 t ha - 1 ). While temporal patterns in crop response matched runoff and erosion response predictions based on plot-scale rainfall simulation experiments, comparison of biomarker and geochemical fingerprinting data indicated that the latter overestimated cultivated land inputs to catchment sediment yield due to inability to discriminate temporary pasture (in rotation) from cultivated land. This discrepancy, however, presents an opportunity since combination of the two datasets revealed the extremely localised nature of erosion from permanent pasture fields in this system (estimated at up to 0.5 t ha - 1 ). The novel use of CSSI and geochemical tracers in tandem provided unique insights into sediment source dynamics that could not have been derived from each method alone. Research

  16. Impacts of peat restoration on peak flow characteristics of upland headwater catchments

    NASA Astrophysics Data System (ADS)

    Allott, Tim; Evans, Martin; Agnew, Clive; Milledge, Dave; Pilkington, Mike; Maskill, Rachael

    2014-05-01

    As part of the current focus on ecosystem services provided by peatlands, there is renewed interest in the hydrology of upland blanket peats and more specifically in the hydrological changes associated with peat erosion and restoration. Peat restoration has often been cited as having potential benefits for downstream flood risk through the reduction of peak flows and increases in storm hydrograph lag times. However, evidence of the impacts of peatland restoration practices on storm hydrology and downstream discharge peaks has been limited by lack of measurement of flow response following restoration programmes. This paper reports a hydrological monitoring programme associated with the restoration of a blanket peatland in the Peak District, UK through the practices of erosion gully blocking and the re-vegetation of bare peat. The main component of the project is a before-after-control-impact (BACI) study on three hectare-scale eroded, bare peat catchments, two of which have been restored and one of which is acting as an unmodified control. Monitoring commenced in early summer 2010, and restoration of the experimental sites by reseeding and gully blocking took place between July 2011 and March 2012. To complement the main study, a broader spatial comparison of the hydrological behaviour of catchments with different degradation and restoration conditions has been made, including (i) an intact reference peatland, (ii) the eroded/bare peat sites, and (iii) a 'late stage' restored area of peatland which was re-vegetated in 2003. Results reveal significant differences between the storm hydrograph characteristics of intact, eroded and restored catchments consistent with the hypotheses that (a) peat erosion significantly decreases storm flow lag times and increases storm flow peaks in these peatland systems and (b) peat restoration reverses these effects. Associated overland flow data suggest that gully blocking and re-vegetation within gully systems are crucial controls on

  17. Spatial distributions of forest stand condition, vegetation ground cover, and soil erosion for evaluating the linkages of sediment transport from hillslopes to streams in headwater catchments

    NASA Astrophysics Data System (ADS)

    Gomi, T.; Kumakura, A.; Mizugaki, S.; Takahisa, F.; Ishikawa, Y.; Uchiyama, Y.

    2011-12-01

    We investigated soil erosion and resultant fine sediment transport in headwater catchments with heterogeneous spatial patterns of forest stand condition and vegetation ground cover. The study was conducted in 7 and 5 ha headwater catchments (Watersheds No.3 and No.4, respectively) in Tanzawa mountains area, 60 km of southwest of Tokyo, Japan. We selected 53 points located within catchments including near stream channels to the ridge line. A 0.5 x 0.5 m plot (1m x 1m) were selected in each point for investigating vegetation biomass, litter cover, soil erosion (e.g., soil pedestal), overstory vegetation condition (type of forest and canopy openness), and soil physical properties (e.g., soil bulk density and particle size). We assumed that high of soil pedestal indicated short term soil erosions by soil splash and related down slope soil movement. Percentages of bare soil in No. 3 tend to greater than ones in No.4. In addition, bare soil slope tended to distributed lower part of hillslopes with > 45° in gradient, where the soil can be transported to streams. Because of the high soil erosion rate in No.3 catchment, suspended sediment and bedload transport in No.3 tended to be greater ones in No.4 catchment. Fingerprinting approach using activities of fallout radionuclides (caesium-137 and excess lead-210) confirmed that some of the fine sediment transport at associated with hillslope soil surface erosion. Findings of this study suggested that processes of catchment scale fine sediment depending on the linkages between hillslope and channels.

  18. Identification of phosphorus emission hotspots in agricultural catchments

    PubMed Central

    Kovacs, Adam; Honti, Mark; Zessner, Matthias; Eder, Alexander; Clement, Adrienne; Blöschl, Günter

    2012-01-01

    An enhanced transport-based management approach is presented, which is able to support cost-effective water quality management with respect to diffuse phosphorus pollution. Suspended solids and particulate phosphorus emissions and their transport were modeled in two hilly agricultural watersheds (Wulka River in Austria and Zala River in Hungary) with an improved version of the catchment-scale PhosFate model. Source and transmission areas were ranked by an optimization method in order to provide a priority list of the areas of economically efficient (optimal) management alternatives. The model was calibrated and validated at different gauges and for various years. The spatial distribution of the emissions shows that approximately one third of the catchment area is responsible for the majority of the emissions. However, only a few percent of the source areas can transport fluxes to the catchment outlet. These effective source areas, together with the main transmission areas are potential candidates for improved management practices. In accordance with the critical area concept, it was shown that intervention with better management practices on a properly selected small proportion of the total area (1–3%) is sufficient to reach a remarkable improvement in water quality. If soil nutrient management is also considered in addition to water quality, intervention on 4–12% of the catchment areas can fulfill both aspects. PMID:22771465

  19. Quantifying suspended sediment sources during flood events in headwater catchments using diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Legout, Cédric; Poulenard, Jérôme; Nemery, Julien; Navratil, Oldrich; Grangeon, Thomas; Evrard, Olivier; Esteves, Michel

    2013-04-01

    Increasing the understanding of the hydro-sedimentary dynamics at the catchment scale requires data on the origin of suspended sediments in addition to the classical measurements of suspended sediment concentrations and discharge. In mountainous environments the extremely high spatial and temporal variability of suspended sediment fluxes suggests that the proportions of suspended sediment sources transiting at outlets may also exhibit strong variations during flood events. However, conventional fingerprinting techniques based on geochemical and radionuclide measurements are time-consuming and rather expensive. They constitute a major limitation to conduct routine characterisation of the source of suspended sediment transiting at outlets that would require the analysis of a large number of samples. We investigated how visible or infrared diffuse reflectance spectroscopy coupled with partial least squares chemometrics techniques could be used to predict the proportion of source material in suspended sediment samples and how it could help understanding the hydro-sedimentary processes occurring during floods. The studied catchment is located in the southern French Alps, draining an area of 22-km². It is composed of black marls, limestones, molasses, undifferentiated deposits and gypsum. Forty-eight source material samples were collected in badlands areas and 328 suspended sediment samples were collected at the outlet during 23 flood events. Spectroscopic measurements were carried out on dried samples. Given that the erosion processes are particle size selective, five size fractions of source material were measured in order to assess the potential alteration of the signatures. As the biogeochemical processes occurring in the river such as iron oxidation could also affect the signatures, source materials that were immersed in the river for durations ranging from 1 day to 9 weeks were analysed. Finally, partial least-squares regression models were constructed on 81

  20. Relating stable isotope and geochemical data to conclude on water residence times in four small alpine headwater catchments with differing vegetation cover

    NASA Astrophysics Data System (ADS)

    Mueller, M. H.; Weingartner, R.; Alewell, C.

    2012-09-01

    The mean water residence time (MRT) in a catchment gives information about storage, flow pathways, sources of water and thus also about retention and release of solutes in a catchment. To our knowledge there are no catchment studies on the influence of vegetation cover change on base flow mean water residence times. The main changes in vegetation cover in the Swiss Alps are massive shrub encroachment and forest expansion into formerly open habitats. Four small and relatively steep catchments in the Swiss Alps (Ursern valley) were investigated to relate different vegetation cover to water residence times and geochemical behaviour of runoff. Time series of water stable isotopes were used to calculate mean water residence times. The high temporal variation of the stable isotope signals in precipitation was strongly dampened in stream base flow samples. Mean water residence times of the four catchments were 64-98 weeks. The strong dampening of our input signal might point to deeper flow paths and mixing of waters of different ages at the catchments outlets. Parent geological materials are mainly gneisses and schists but they can contain dolomite, carbonate or gypsum rich zones. The major part of the quickly infiltrating precipitation likely percolates through these deeper zones. Relatively high stream water pH, Ca and SO42- concentrations in micro catchment outlets support this conclusion. We conclude that in mountainous headwater catchments with relatively thin soil layers the geological and topographical situation and snow dynamics influence storage, mixing and release of meteoric waters and its geochemistry in a stronger way than vegetation cover or catchment size do.

  1. 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

  2. Response of near-stream surface connectivity to water table dynamics during rainfall events at a small headwater catchment (Luxembourg)

    NASA Astrophysics Data System (ADS)

    Frentress, Jay; Martínez-Carreras, Núria; Pfister, Laurent; McDonnell, Jeff

    2014-05-01

    The controls on non-linear streamflow response to changing streamflow sources during precipitation events are poorly understood. Here, we investigate the linkages between surface saturation development and streamflow under a range of wetness conditions for a forested headwater catchment in Luxembourg. Previous work at this site shows a threshold response in stream discharge to changes in soil moisture. This non-linearity is thought to reflect the development of saturation connectivity that drives streamflow response. Furthermore, the catchment has typically large rainfall-runoff ratios during winter, accompanied by long delays to peak after the onset of rainfall. To better understand controls on these behaviors, we examined the response of near-stream surface saturation development to incident precipitation, discharge, and fluctuating groundwater levels during rain events. Specifically, we sought to test the hypothesis that threshold-like response behavior exists between near-stream surface saturation and discharge, as well as quantify changes in surface saturated zone chemistry to better understand mixing between end-member sources during events. We used ground-based thermal infrared imagery to measure surface saturation development in a 4 by 6 m zone in the riparian area. Imagery collected over several months was analyzed to calculate the proportion of saturated area. Water samples from this saturated riparian area, nearby piezometers as well as discharge were collected for analysis of water isotopes, major cations/anions, and silica concentrations. Data analysis is ongoing but preliminary results indicate that saturation extent exhibits a non-linear, threshold-like response to discharge and antecedent wetness conditions. Surface saturation showed strong hysteresis with near-stream groundwater levels, with saturated areas expanding ahead of increasing groundwater levels. As the proportion of saturated area increased during rainfall events, the saturated riparian

  3. 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.

  4. Drivers of erosion and suspended sediment transport in three headwater catchments of the Mexican Central Highlands

    NASA Astrophysics Data System (ADS)

    Duvert, Clément; Gratiot, Nicolas; Evrard, Olivier; Navratil, Oldrich; Némery, Julien; Prat, Christian; Esteves, Michel

    2010-11-01

    Quantifying suspended sediment exports from catchments and understanding suspended sediment dynamics within river networks is important, especially in areas draining erodible material that contributes to the siltation of downstream reservoirs and to the degradation of water quality. A one-year continuous monitoring study of water and sediment fluxes was conducted in three upland subcatchments (3.0, 9.3, and 12.0 km 2) located within the Cointzio basin, in the central volcanic highlands of Mexico (Michoacán state). Two subcatchments generated high sediment exports (i.e., Huertitas, 900-1500 t km - 2 y - 1 and Potrerillos, 600-800 t km - 2 y - 1 ), whereas the third subcatchment was characterized by a much lower sediment yield (i.e., La Cortina, 30 t km - 2 y - 1 ). Such disparities in subcatchment behaviours were associated with the presence of severely gullied areas in Huertitas and Potrerillos rather than with rainfall erosivity indices. An adapted classification of hysteretic patterns between suspended sediment concentration (SSC) and discharge was proposed because 42% of flood events contributing to 70% of sediment export were not discriminated by the classical clockwise/anticlockwise typology. This new classification allowed the identification of relationships in the hydrosedimentary responses of successive floods. A stream transport capacity limit was also detected during hydrograph recession phases. Overall, hydrosedimentary processes proved to be seasonally dependent: sediment export was repeatedly limited by the stream transport capacity during the first part of the rainy season, whereas a channel minimum erosivity threshold was frequently reached at the end of the season.

  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. Temporal and spatial changes in dissolved organic carbon concentration and fluorescence intensity of fulvic acid like materials in mountainous headwater catchments

    NASA Astrophysics Data System (ADS)

    Terajima, Tomomi; Moriizumi, Mihoko

    2013-02-01

    SummaryDissolved organic carbon (DOC) such as humic substances are key to understanding the aquatic environment in catchments, because they, containing a large number of phenolic and carboxylic acid groups, adsorb many kinds of inorganic materials and also affect nutrition and carbon transport in catchments. To understand the detailed DOC dynamics, we conducted hydrological observations at mountainous headwater catchments dominated by different vegetation types (planted evergreen coniferous forest of 1.29 ha and natural deciduous broadleaf forest of 1.28 ha). The relationship between DOC concentrations and fluorescence intensity of fulvic acid-like materials (F-FAM) were positively correlated in both catchments but different between soil extracts, baseflow, and near surface flow represented by biomat flow. The ratios of change in F-FAM to that in DOC concentration (F-FAM/DOC) were higher in the baseflow (about 6 in both catchments) and lower in the soil extracts (about 4.5 in both catchments, respectively). However, the relationship in stormflow was distributed between the trends of baseflow and soil extracts. The higher F-FAM/DOC in baseflow may thus indicate that DOC (and FAM) in groundwater discharge mainly contributed to the stream flow, and the stormflow mainly reflect subsurface flow through soil during most rainstorms. In contrast, a high F-FAM/DOC ratio (>6) appeared in the stormflow of both catchments especially during large storms of short duration and high intensity following a dry antecedent period. The F-FAM/DOC in biomat flow developing distinctly in the coniferous catchment was high (about 6.5). Thus, rapid shallow subsurface flow through the biomat or near-surface of slopes might explain the unique transport dynamics of DOC and FAM in stormflows with the high F-FAM/DOC ratio. These results imply that the DOC and FAM relationship responds variably depending on both the distribution of soil organic matter and rainwater flow paths in steep slopes as

  7. Do fire disturbances account for missing C in snow dominated headwater catchments in NM?

    NASA Astrophysics Data System (ADS)

    Perdrial, J. N.; Brooks, P. D.; Swetnam, T.; Lohse, K. A.; Rasmussen, C.; Harpold, A. A.; Litvak, M. E.; Broxton, P. D.; Mitra, B.; Condon, K.; Huckle, D. M.; Vazquez, A.; Lybrand, R. A.; Holleran, M.; Orem, C. A.; Meixner, T.; Chorover, J.

    2013-12-01

    How do fires affect the potential for long term carbon (C) sequestration in the forests of western North America? We quantified current C fluxes (net ecosystem exchange [NEE] and dissolved & particulate stream and ground water fluxes) and pools (above and below ground biomass, [AGB, BGB], soil C) in three catchments of the Jemez River Basin Critical Zone Observatory. Our estimates revealed that study systems are dominated by gaseous fluxes (ranging from 3,200 to 3,900 kg ha-1 yr-1over three years) with only small losses to streams as dissolved or particulate C (5 to 30 kg ha-1 yr-1) or to GW (1-6 kg ha-1 yr-1) rendering these systems substantial sinks for atmospheric C. Our estimates for biomass (20,000 - 240,000 kg ha-1) and soil C (80.000 and 160.000 kg ha-1) are comparable to stocks of similar soil and vegetation types (Lal 2005; North et al. 2009) and at current uptake rates only ~ 50-100 years are necessary for accumulation. Since old soil C accumulated over a longer period of time, current uptake rates are either higher than past ones and/or disturbances reduced the stocks in the past. Logging is documented in these systems but cannot explain the bulk of unaccounted C. Wildfires in contrast have occurred repeatedly in the past and impacted the C budget by reducing stocks (e.g. ~ 8% of AGB, ) during each fire. Additionally, uptake rates after fire are reduced until vegetation regrowth, with microbial respiration and thus carbon loss dominating in the interim. Post-fire debris flows (estimate 800 - 1140 kg C ha-1 after a recent fire in NM) present an additional sink. Together, our results are used to test the hypothesis that recurring wildfires strongly impact the C-balance of seasonally snow-covered forests in the SW US leading to oscillation between sources and sinks for C. Lal R (2005). Forest Ecol Manag 220 (1-3):242-258. North M, Hurteau M, Innes J (2009). Ecol Appl 19 (6):1385-1396.

  8. 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

  9. Hydrologic controls on the sources and dynamics of dissolved organic matter in an agricultural catchment in the Central Valley, California (U.S.A.)

    NASA Astrophysics Data System (ADS)

    Dyda, R. Y.; Hernes, P. J.; Spencer, R. G.; Pellerin, B. A.; Bergamaschi, B. A.

    2008-12-01

    The influence of agricultural practices on the dynamics of dissolved organic matter (DOM) cycling in river systems is poorly understood. We investigated molecular compositions of DOM at 14 sites in an agriculturally-impacted catchment (Willow Slough; 415 km2) under several different flow regimes over the course of two years in order to investigate the influence of sub-catchments on the biogeochemistry at the mouth of the catchment. The Willow Slough catchment area includes eastern foothills of the inner Coast Range to the alluvial plains and encompasses diverse land uses, including natural grasslands, orchards, viticulture and pasture, all draining toward the Sacramento River. Knowledge of the composition of DOM composition is crucial, as dissolved organic carbon (DOC) can form EPA-regulated carcinogenic compounds during the drinking water disinfection process and is therefore considered a drinking water constituent of concern. Willow Slough offers the opportunity to examine carbon source, cycling and transportation through multiple flowpaths and land uses that are common in Californian agricultural watersheds. As a constituent of DOM, lignin phenols provide information on the source, composition, quality and degradation state of DOM. Uniquely derived from vascular plants, lignin phenols can be used to distinguish between angiosperm and gymnosperm tissues and carbon-normalized yields can offer insight on the proportion of vascular plant-derived carbon versus in-situ production. Throughout the Willow Slough watershed, ratios of syringyl to vanillyl and cinnamyl to vanillyl lignin phenols show that the vascular plant component of DOM can be primarily attributed to non-woody angiosperm tissues. Lower lignin phenol concentrations and carbon-normalized yields were observed in the headwaters (0.1-0.6 mg/100mg OC and 2.6-33 μg/L) versus the mouth (0.7-2.0 mg/100mg OC and 25-72 μg/L), indicating that mid-catchment tributaries play important roles in determining the

  10. 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. PMID:24522791

  11. 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

  12. 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

  13. Determining Solute Sources and Water Flowpaths in a Forested Headwater Catchment: Advances With the Ca-Sr-Ba Multi-tracer

    NASA Astrophysics Data System (ADS)

    Bullen, T. D.; Bailey, S. W.; McGuire, K. J.; Zimmer, M. A.; Ross, D. S.

    2011-12-01

    Determining solute sources and water flowpaths in catchments is of critical importance to development of models that effectively describe catchment function. For solutes in soil water and stream water, simple mass balance models that compare precipitation input to catchment outlet compositions can predict average mineral weathering contributions for the catchment as a whole, but fail to provide information about either variability of contributions from different portions of the catchment and different soil depths or processes such as ion exchange and biological cycling. In order to better understand how forested headwater catchments function, we are interpreting concentration and isotope ratios of the alkaline earth elements Ca, Sr and Ba in streamwater, groundwater, the soil ion exchange pool and plants in a hydropedologic context at the 41 hectare hydrologic reference catchment (Watershed 3) at the Hubbard Brook Experimental Forest, New Hampshire, USA. This forested headwater catchment consists of a beech-birch-maple-spruce forest growing on vertically- and laterally-developed Spodosols and Inceptisols formed on granitoid glacial till that mantles Paleozoic metamorphic bedrock. Across the watershed in terms of the soil ion exchange pool, the forest floor has high Sr/Ba and Ca/Sr ratios, mineral soils have intermediate Sr/Ba and low Ca/Sr, and relatively unweathered till in the C horizon has low Sr/Ba and high Ca/Sr. Waters moving through these various compartments will obtain Sr/Ba and Ca/Sr ratios reflecting these characteristics, and thus variations of Sr/Ba and Ca/Sr of streamwater provide evidence of the depth of water flowpaths feeding the streams. 87Sr/86Sr of exchangeable Sr spans a broad range from 0.715 to 0.725, with highest values along the mid-to upper flanks of the catchment and lowest values in a broad zone along the central axis of the catchment associated with numerous groundwater seeps. Thus, variations of 87Sr/86Sr in streamwater provide

  14. Temporal Variability of Soil Moisture and Its Relation With Features of Sediment Transport In A Headwater Catchment In The Central Pyrenees

    NASA Astrophysics Data System (ADS)

    Seeger, M.; Errea, M.-P.; Beguería, S.; Arnáez, J.; Garcia-Ruiz, J. M.

    Due to the recent land-use history of the mountain areas in the Mediterranean, most of the headwater catchments of the central part of the Spanish Pyrenees are occupied nowadays by abandoned fields. They are slowly colonised by scrub and forest vegetation, showing now a heterogeneous and patchy cover of herbaceous, scrubs and few forest cover. The soils are shallow, loamy, rich in carbonates and partially strongly eroded. The investigated Arnás catchment, with approx. 3 km2, located completely on flysh, is a representative area for the whole central parts of the former cultivated Pyrenees. Since 1996 discharge and sediment concentrations are monitored automatically for the whole catchment. During 3 years, from 1996 to 1998, soil water measurements were carried out on 25 morphological distinct placements. The measurements were taken once a week or forthcomingly with the TDR-method in the upper 20 cm of the soil. The study of the patterns of sediment production shows two clearly identifiable types: one, with a clockwise hysteretic loop ­the sediment peak follows the flood peak­ during the moist season, where a big number of flood events occur, and another one with a counter -clockwise hysteretic loop ­the sedim ent peak precedes the flood peak­ during the dry season or after long periods without flood events. On the other hand, the soil moisture data show that the topsoil in the catchment is often saturated with water and maintains, due to its poor drainage capacity, high moisture levels during a long time. Aim of this work is to investigate the relationship between soil moisture and sediment transport characteristics, especially if there can be found a threshold value of soil moisture as an average of the catchment or at special points, which makes the hysteretic loop of catchment discharge and sediment concentration change. Preliminary investigations show that soils containing moisture below field capacity are related to the counter-clockwise hysteretic loops.

  15. Rainfall Threshold For Slope-Channel Connectivity In Agricultural Catchment

    NASA Astrophysics Data System (ADS)

    Święchowicz, Jolanta

    2015-04-01

    Many rainfall events lead to the transfer of soil material from one slope section to another, which does not notably alter slope relief (first transfer threshold). Some events lead to the transfer of soil from the water divide to the footslope (second transfer threshold). In a few exceptional cases, soil material is transferred directly into river channels due to severe erosion moving large quantities of soil over long distances. Extreme events lead to the transfer of soil material down the entire slope length, its deposition at the footslope and even further across the valley floor. Sediment is transferred directly from slopes to river channels (third transfer threshold or slope-channel connectivity threshold). This work presents rainfall threshold values and probability of slope-to-river sediment transfer in a foothill agricultural catchment in Poland. The study is based on research performed in the Dworski Potok Catchment (227-275 m a.s.l.), which is a small agricultural foothill catchment (0.29 km2), situated in a moderate climate zone, with slopes covered with loess-like formations. The paper uses precipitation data for the period 1987-2009 obtained at the Łazy Field Research Station near Bochnia (Poland) and long-term field data on splash (2007-2009), slope wash (2007-2009) and linear erosion (1998-2009) on slopes. In Dworski Potok Catchment change in the slope relief was brought about by short transformation periods, during which soil erosion by water took place, especially if it was caused by events of high magnitude and low frequency. Those periods which, depending on the criterion adopted, lasted from 0.3 to 4% of the time of study were the most interesting and effective episodes in the development of slopes. It was determined that in the researched multi-year period, the transfer of soil material was possible to occur after certain parameters had exceeded the following threshold values: EI30 = 40.5 MJmmha-1h-1 or I30 = 9.8 mmh-1 for the first transfer

  16. Critical source times for nutrient loss in agricultural catchment streams

    NASA Astrophysics Data System (ADS)

    Melland, Alice; Shore, Mairead; Mellander, Per-Erik; McDonald, Noeleen; Shortle, Ger; Murphy, Paul; Jordan, Phil

    2014-05-01

    Identifying periods of the year when there is a high risk of incidental nutrient loss from farms via runoff to streams underpins current nutrient management legislation in Europe. This research explored high-temporal resolution nutrient transfer patterns relative to the time that manure and fertiliser are prohibited from being spread (the mandatory spreading 'closed' period) in five Irish agricultural catchments. Catchment nutrient losses during the 12 week closed periods in 2009-10, 2010-11 and 2011-12 were compared with losses during the remainder of the year, and with losses in the two week 'shoulder' periods immediately before and after the closed period. The closed period losses were assumed to be residual from soil nutrient stores and the 'shoulder' periods were considered to also include incidental losses. Nutrient loss was measured at sub-hourly frequency as total phosphorus (P) and total oxidised nitrogen (mostly nitrate-N) fluxes in streamflow. The streamflow fluxes showed that the proportion of the annual nitrate-N loss occurring during the closed periods (33-61%) was high compared with the remainder of the year. Six to ten times more nitrate-N loss occurred in the two weeks after, compared with the two weeks before, the closed period. These two week 'shoulder' period losses were, on average, less than or equal to 2.5 kg nitrate-N/ha and 9% of total annual nitrate-N loss in streamflow. On average, 40-53% of the annual P loss occurred during the closed periods but in a runoff-prone catchment in a year with a wet summer, the closed period was the less risky period. Similar to nitrate-N, two to twenty times more P loss occurred in the two weeks after, compared with the two weeks before, the closed period. These shoulder period losses were, on average, less than or equal to 0.027 kg/ha and 4.2% of total annual P loss in streamflow. The proportion of the shoulder period loss that could be attributed to recently spread nutrients was not known but can be

  17. Quantifying subsurface mixing of water and nutrients in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Van der Velde, Y.; Torfs, P.; Van Der Zee, S.; Uijlenhoet, R.

    2011-12-01

    The distribution of time it takes water from the moment of rainfall to reach the catchment outlet is widely used to characterize catchment-scale groundwater-surface water interactions, catchment vulnerability to pollution spreading and pollutant loads from catchments to downstream waters. However, this distribution tends to vary in time driven by rainfall and evapotranspiration, which compromises the applicability of a single travel time distribution as catchment characteristic. Recent studies suggested that subsurface mixing controls to what extent dynamics in rainfall and evpotranspiration are translated into dynamics of travel time distributions of individual water flows. This new insight in hydrologic functioning of catchments requires new definitions and concepts that link dynamics of catchment travel time distributions to the degree of subsurface mixing. We propose the concept of Refresh Rate Functions (RRF) and will demonstrate how RRFs directly quantify subsurface mixing within a catchment, allow for deriving transient as well as temporally averaged travel time distributions of a catchment and are largely independent of weather or climate. The presented analyses will use a unique dataset of high-frequent nitrate concentrations in an agricultural catchment in the Netherlands to reveal the effects of mixing dynamics inside a catchment on stream water nitrate concentrations. These measurements will be compared with calculations by a spatially distributed groundwater model and conceptual models of water flow and solute transport. Remarkable findings are the large contrasts in discharge behavior expressed in travel time between lowland and sloping catchments and the strong relation between evapotranspiration and stream water nitrate concentration dynamics.

  18. A national scale monitoring network for nutrients in agriculture dominated headwaters in the Netherlands

    NASA Astrophysics Data System (ADS)

    Broers, H. P.; Rozemeijer, J.; Klein, J.

    2012-04-01

    Although specific monitoring networks exist in the Netherlands which assess the leaching of nutrients to surface waters and groundwater, none of them was capable to quantify the effects of nutrient reduction schemes to agriculture dominated headwaters. Thus, an important link was missing which relates the nutrient concentrations measured in shallow groundwater at farm scale to nutrient concentrations measured at the scale of Water Framework Directive water bodies. A new network was composed using existing monitoring locations and water quality time series owned by the 24 water boards in the Netherlands. Only monitoring locations were selected where no other pollution sources , such as water sewage treatment plants were influencing water quality. Eventually, 168 monitoring locations were selected to assess compliance to environmental standards and 80 for trend analysis. Compliance was tested applying environmental quality standards (EQS) based on summer averaged concentrations, which are set by the water boards and which are water type and location dependent. Compliance was strongly weather dependent, and only 24% of the locations complied for N and P under all weather conditions. Trends were assessed using a combination of seasonal Mann-Kendall tests and Theil-Sen robust lines for individual time series, and aggregating those trends to acquire median and average trend slopes for the sand, clay and peat regions in the Netherlands. Significant downward trends were demonstrated for N and P over the whole period (slopes between -0,55 mgN/l and -0.015 and 0.02 mg P/l per 10 year). Slopes were even more pronounced for winter concentrations of N (-0.89 mg N/l per 10 year). The slopes were relevant and environmentally significant in relation to the height of the EQS and were attributed to the effective reduction of nutrient leaching as the result of adapted farming practices. The presentation will highlight and evaluate choices in the design of the newly composed network

  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. Complementarities of novel and conventional tracer techniques: how can they help us to better understand streamflow generation processes in headwater catchments?

    NASA Astrophysics Data System (ADS)

    Martínez-Carreras, N.; Bogaard, T.; Frentress, J.; Foppen, J. W.; Wetzel, C. E.; Ector, L.; Hissler, C.; McDonnell, J. J.; Pfister, L.

    2012-04-01

    Over the past decades geochemical and isotopic tracers have been widely used to obtain insights into internal catchment dynamics and to delineate and constrain hydrological flowpaths. Not only water stable isotopes, but also dissolved silica, major ions and cations can be used to separate hydrographs into different components. Nevertheless, further progress has been stymied by limitations such as unrealistic mixing assumptions, unstable end-member solutions and temporally variable input concentrations. Here, we investigate the potential for innovative tracer techniques to bring new momentum to our understanding of streamflow generation processes in headwater catchments. In recent years, new techniques have indeed emerged, each revealing their own advantages and limitations. Pfister et al. (2009) demonstrated the potential for diatoms (unicellular, eukaryotic algae) to help detect the onset/cession of surface runoff and quantify the geographical sources of surface water. More recently, Foppen et al. (2011) used synthetic DNA to characterize hydrological processes, both in surface waters and in the subsurface. Temperature has also been widely used as a tracer. Distributed temperature sensing with a spatial resolution of 0.5m and temporal resolution of 2min via fibre optic cable have indeed been applied to locate lateral inflow in streams (Westhoff et al., 2011). Also, ground-based thermal imagery has been proven to be a simple, practical tool for mapping saturated area connectivity and dynamics (Pfister et al., 2010). The main objective of this work is to evaluate and discuss the respective complementarities of these techniques by shedding light on both their advantages and limitations. This will be done based on examples from the extensive experimental work performed in the headwater streams of Luxembourg.

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

    NASA Astrophysics Data System (ADS)

    Thomas, Z.; Abbott, B. W.; Troccaz, O.; Baudry, J.; Pinay, G.

    2015-09-01

    Direct and indirect effects from agriculture, urbanization, and resource extraction have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. The capacity of a watershed to remove or retain nutrients is a function of biotic and abiotic conditions across the terrestrial-aquatic gradient including soil, groundwater, riparian zone, and surface water. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments. We analysed a five-year, high frequency water chemistry dataset from 3 catchments ranging from 2.3 to 10.8 km2 in northwestern France. Catchments differed in the relationship between hydrology and solute concentrations, associated with catchment characteristics such as hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness appeared to have greater transient storage and residence time, buffering the catchment to fluctuations in water chemistry, reflected in relatively invariant carbon and nutrient chemistry across hydrologic conditions. Conversely, the catchments with smoother, thinner soils responded to both intra- and inter-annual hydrologic variation with high concentrations of PO43- and NH4+ during low flow conditions and strong increases in DOC, sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land use) 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 elemental fluxes is 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 catchment buffering capacity and probability of human

  2. 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

  3. Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study

    NASA Astrophysics Data System (ADS)

    Aubert, A. H.; Gascuel-Odoux, C.; Gruau, G.; Akkal, N.; Faucheux, M.; Fauvel, Y.; Grimaldi, C.; Hamon, Y.; Jaffrézic, A.; Lecoz-Boutnik, M.; Molénat, J.; Petitjean, P.; Ruiz, L.; Merot, P.

    2013-04-01

    High-frequency, long-term and multisolute measurements are required to assess the impact of human pressures on water quality due to (i) the high temporal and spatial variability of climate and human activity and (ii) the fact that chemical solutes combine short- and long-term dynamics. Such data series are scarce. This study, based on an original and unpublished time series from the Kervidy-Naizin headwater catchment (Brittany, France), aims to determine solute transfer processes and dynamics that characterise this strongly human-impacted catchment. The Kervidy-Naizin catchment is a temperate, intensive agricultural catchment, hydrologically controlled by shallow groundwater. Over 10 yr, five solutes (nitrate, sulphate, chloride, and dissolved organic and inorganic carbon) were monitored daily at the catchment outlet and roughly every four months in the shallow groundwater. The concentrations of all five solutes showed seasonal variations but the patterns of the variations differed from one solute to another. Nitrate and chloride exhibit rather smooth variations. In contrast, sulphate as well as organic and inorganic carbon is dominated by flood flushes. The observed nitrate and chloride patterns are typical of an intensive agricultural catchment hydrologically controlled by shallow groundwater. Nitrate and chloride originating mainly from organic fertilisers accumulated over several years in the shallow groundwater. They are seasonally exported when upland groundwater connects with the stream during the wet season. Conversely, sulphate as well as organic and inorganic carbon patterns are not specific to agricultural catchments. These solutes do not come from fertilisers and do not accumulate in soil or shallow groundwater; instead, they are biogeochemically produced in the catchment. The results allowed development of a generic classification system based on the specific temporal patterns and source locations of each solute. It also considers the stocking period

  4. 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.

  5. 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

  6. Antecedent conditions, hydrological connectivity and anthropogenic inputs: Factors affecting nitrate and phosphorus transfers to agricultural headwater streams.

    PubMed

    Outram, Faye N; Cooper, Richard J; Sünnenberg, Gisela; Hiscock, Kevin M; Lovett, Andrew A

    2016-03-01

    This paper examines relationships between rainfall-runoff, catchment connectivity, antecedent moisture conditions and fertiliser application with nitrate-N and total phosphorus (TP) fluxes in an arable headwater catchment over three hydrological years (2012-2014). Annual precipitation totals did not vary substantially between years, yet the timing of rainfall strongly influenced runoff generation and subsequent nitrate-N and TP fluxes. The greatest nitrate-N (>250 kg N day(-1)) and TP (>10 kg TP day(-1)) fluxes only occurred when shallow groundwater was within 0.6m of the ground surface and runoff coefficients were greater than 0.1. These thresholds were reached less frequently in 2012 due to drought recovery resulting in lower annual nitrate-N (7.4 kg N ha(-1)) and TP (0.12 kg P ha(-1)) fluxes in comparison with 2013 (15.1 kg N ha(-1); 0.21 kg P ha(-1)). The wet winter of 2013 with elevated shallow groundwater levels led to more frequent activation of sub-surface pathways and tile drain flow. Throughout the period, dry antecedent conditions had a temporary effect in elevating TP loads. Evidence of TP source exhaustion after consecutive storm events can be attributed to the repeated depletion of temporarily connected critical source areas to the river network via impermeable road surfaces. Fertiliser application varied considerably across three years due to differences in crop rotation between farms, with annual N and P fertiliser inputs varying by up to 21% and 41%, respectively. Proportional reductions in annual riverine nitrate-N and TP loadings were not observed at the sub-catchment outlet as loadings were largely influenced by annual runoff. Nitrate loadings were slightly higher during fertiliser application, but there was little relationship between P fertiliser application and riverine TP load. These data indicate that this intensive arable catchment may be in a state of biogeochemical stationarity, whereby legacy stores of nutrients buffer against changes

  7. Investigating Runoff Generation in a Headwater Forested Catchment Using a Typology of Nonlinear Storage-Discharge Relationships

    NASA Astrophysics Data System (ADS)

    L'Heureux, C.; Ali, G. A.; Roy, A. G.; Turmel, M.; Courchesne, F.

    2011-12-01

    We investigated the "switching on and off" of runoff generation in a small forested catchment, the Hermine, characterized by moderately steep surface topography and an extensive but discontinuous fragipan-like horizon at an average depth of 0.75 m within the soil mantle. A water table dataset (94 wells, 50 sampling campaigns) was used to derive point-scale perched groundwater (PGW) storage variables illustrating the presence or absence of surface water, the soil deficit to saturation, the location of dry, filling and spilling subsurface hollows, and the water table elevation above an underlying filled subsurface hollow. A typology of storage-discharge relationships was also built to differentiate locations driven by threshold-crossing between two extreme states from other locations experiencing a continuum of hydrologic states. We found that spatial patterns of PGW storage were initially important during a rainstorm to trigger a response at the catchment outlet but then remained unchanged even though streamflows continued to increase up to an order of magnitude higher. While discontinuous storage-discharge relationships were observed at the point-scale, continuous relationships were rather observed at the aggregated catchment-scale, thus implying that the emergent catchment behaviour could be described as a continuum of hydrological states. At the point-scale, storage-discharge relationships were used to assess the spatial heterogeneity of runoff processes as their associated shapes and thresholds indicated the timing of either preferential flow activation or subsurface connectivity enhancement. At the catchment scale, a critical outflow parameter of 1 L.s-1 was found to transcend small-scale process heterogeneity as it signalled the triggering of the catchment internal stormflow generation mechanisms. Our typology of nonlinear relationships was especially useful for grouping similar runoff responses both in space and time. We therefore make a plea for cross

  8. 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...

  9. 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...

  10. 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.

  11. 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...

  12. 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

  13. 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

  14. 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. PMID:23313906

  15. 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

    NASA Astrophysics Data System (ADS)

    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, KOC. 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.

  16. Mixing and connectivity of groundwater and surface water within the near-stream saturated zone of a small headwater catchment (Luxembourg)

    NASA Astrophysics Data System (ADS)

    Frentress, J. J.; Martinez-Carreras, N.; Pfister, L.; McDonnell, J. J.

    2013-12-01

    Near-stream, surface saturated zones are key areas where stream runoff occurs. These areas comprise a small proportion of a catchment but play a disproportionate role in routing rainfall to the stream channel and are often the hotspots for geochemical and biogeochemical transformation. Despite their importance to streamflow generation and chemistry, little is known about mixing processes that occur in these saturated areas, where subsurface, surface water and event rainfall meet, mix and move to the stream channel. Detection and quantification of surface saturated area mixing and connectivity has proved to be a substantial measurement challenge. Recently however, a novel technique using ground-based infrared imagery has been used to document surface saturated area expansion as well as detect groundwater inputs to the stream. Here, we combine ground-based infrared imagery, geochemical and isotopic tracers, as well as subsurface hydrometrics to quantify mixing and connectivity between surface and subsurface streamflow sources and their connectivity to the storm hydrograph. We instrumented a small riparian zone at the headwater of the 45 ha Weierbach catchment (Luxembourg), whose shallow soils and underlying schist bedrock offer an ideal location for investigating surface-subsurface mixing and connectivity. A FLIR SC325 infrared camera was installed to measure surface saturation dynamics during multiple rainfall events while subsurface exfiltration was estimated using vertical flux rods and a series of piezometers at the riparian/hillslope interface. Geochemical and isotopic characterization of rainfall, surface and subsurface sources was obtained for three rainfall events during the study period. We anticipate that results from this ongoing work will help to quantify surface and subsurface mixing within the near-stream saturated zone as well as identify controls on connectivity of surface and subsurface streamflow sources during rainfall events.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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

    2016-01-01

    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

  2. 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

  3. [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. PMID:27548958

  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. 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

  6. 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...

  7. 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. PMID:25840482

  8. 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.

  9. 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

  10. Estimation of mean residence times of subsurface waters using seasonal variation in deuterium excess in a small headwater catchment in Japan

    NASA Astrophysics Data System (ADS)

    Kabeya, Naoki; Katsuyama, Masanori; Kawasaki, Masatoshi; Ohte, Nobuhito; Sugimoto, Atsuko

    2007-01-01

    We measured deuterium excess (d = D - 818O) in throughfall, groundwater, soil water, spring water, and stream water for 3 years in a small headwater catchment (Matsuzawa, 0.68 ha) in the Kiryu Experimental Watershed in Japan. The d value represents a kinetic effect produced when water evaporates. The d value of the throughfall showed a sinusoidal change (amplitude: 6.9 relative to Vienna standard mean ocean water (V-SMOW)) derived from seasonal changes in the source of water vapour. The amplitude of this sinusoidal change was attenuated to 1.3-6.9 V-SMOW in soil water, groundwater, spring water, and stream water. It is thought that these attenuations derive from hydrodynamic transport processes in the subsurface and mixing processes at an outflow point (stream or spring) or a well. The mean residence time (MRT) of water was estimated from d value variations using an exponential-piston flow model and a dispersion model. MRTs for soil water were 0-5 months and were not necessarily proportional to the depth. This may imply the existence of bypass flow in the soil. Groundwater in the hillslope zone had short residence times, similar to those of the soil water. For groundwater in the saturated zone near the spring outflow point, the MRTs differed between shallow and deeper groundwater; shallow groundwater had a shorter residence time (5-8 months) than deeper groundwater (more than 9 months). The MRT of stream water (8-9 months) was between that of shallow groundwater near the spring and deeper groundwater near the spring. The seasonal variation in the d value of precipitation arises from changes in isotopic water vapour composition associated with seasonal activity of the Asian monsoon mechanism. The d value is probably an effective tracer for estimating the MRT of subsurface water not only in Japan, but also in other East Asian countries influenced by the Asian monsoon. Copyright

  11. The impact of land management in agricultural catchments on groundwater pollution levels

    NASA Astrophysics Data System (ADS)

    Matysik, Magdalena

    2014-10-01

    Agricultural activity results in water pollution from nitrogen and phosphorus compounds. Increased concentrations of nitrogen compounds pose a threat to animal and human health. The purpose of this study was to determine the impact of agriculture in a catchment basin on the level of groundwater pollution from biogenic compounds. Spatial analysis of the land cover was conducted using a GIS and was based on data from the Corine Land Cover databases.

  12. Sediment fingerprinting in agricultural catchments: A critical re-examination of source discrimination and data corrections

    NASA Astrophysics Data System (ADS)

    Smith, Hugh G.; Blake, William H.

    2014-01-01

    Fine sediment source fingerprinting techniques have been widely applied in agricultural river catchments. Successful source discrimination in agricultural environments depends on the key assumption that land-use source signatures imprinted on catchment soils are decipherable from those due to other landscape factors affecting soil and sediment properties. In this study, we re-examine this critical assumption by investigating (i) the physical and chemical basis for source discrimination and (ii) potential factors that may confound source un-mixing in agricultural catchments, including particle size and organic matter effects on tracer properties. The study is situated in the River Tamar, a predominantly agricultural catchment (920 km2) in south-west England that has also been affected by mining. Source discrimination focused on pasture and cultivated land uses and channel banks. Monthly, time-integrated suspended sediment samples were collected across seven catchments for a 12-month period. Physical and chemical properties measured in source soils and sediment included fallout radionuclides (137Cs, excess 210Pb), major and minor element geochemical constituents, total organic carbon and particle size. Source discrimination was entirely dependent on differences in tracer property concentrations between surface and sub-surface soils. This is based on fallout radionuclide concentrations that are surface-elevated, while many geochemical properties are surface-depleted due to weathering and pedogenetic effects, although surface soil contamination can reverse this trend. However, source discrimination in the study catchments was limited by (i) rotation of cultivated and pasture fields resulting in reduced differences between these two sources, and (ii) the cultivated source signature resembling a mix of the pasture and channel bank sources for many tracer properties. Furthermore, a combination of metal pollution from abandoned historic mines and organic enrichment of

  13. Effect of subsurface drainage on streamflow in an agricultural headwater watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Artificial drainage, also known as subsurface or tile drainage is paramount to sustaining crop production agriculture in the poorly-drained, humid regions of the world. Hydrologic assessments of individual plots and fields with tile drainage are becoming common; however, a major void exists in our u...

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

    USGS Publications Warehouse

    Rice, K.C.; Hornberger, G.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.

  16. Scale dependent parameterization of soil hydraulic conductivity in 3D simulation of hydrological processes in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Fang, Zhufeng; Bogena, Heye; Kollet, Stefan; Vereecken, Harry

    2016-05-01

    In distributed hydrological modelling one often faces the problem that input data need to be aggregated to match the model resolution. However, aggregated data may be too coarse for the parametrization of the processes represented. This dilemma can be circumvented by the adjustment of certain model parameters. For instance, the reduction of local hydraulic gradients due to spatial aggregation can be partially compensated by increasing soil hydraulic conductivity. In this study, we employed the information entropy concept for the scale dependent parameterization of soil hydraulic conductivity. The loss of information content of terrain curvature as consequence of spatial aggregation was used to determine an amplification factor for soil hydraulic conductivity to compensate the resulting retardation of water flow. To test the usefulness of this approach, continuous 3D hydrological simulations were conducted with different spatial resolutions in the highly instrumented Wüstebach catchment, Germany. Our results indicated that the introduction of an amplification factor can effectively improve model performances both in terms of soil moisture and runoff simulation. However, comparing simulated soil moisture pattern with observation indicated that uniform application of an amplification factor can lead to local overcorrection of soil hydraulic conductivity. This problem could be circumvented by applying the amplification factor only to model grid cells that suffer from high information loss. To this end, we tested two schemes to define appropriate location-specific correction factors. Both schemes led to improved model performance both in terms of soil water content and runoff simulation. Thus, we anticipate that our proposed scaling approach is useful for the application of next-generation hyper-resolution global land surface models.

  17. Estimation of groundwater contribution in runoff from small agricultural dominated catchments

    NASA Astrophysics Data System (ADS)

    Deelstra, Johannes; Jansons, Viesturs; Lagzdiņš, Ainis

    2013-04-01

    Under poor natural drainage condition, agricultural land has to be provided with subsurface drainage systems to discharge excess water from the rootzone, thereby guaranteeing optimal cropping conditions during the growing season, while in addition facilitating land preparation. Subsurface drainage systems can significantly contribute in runoff and nutrient loss generation. A secondary effect of drainage systems is that it reduces surface runoff and thereby erosion and phosphorus loss. In addition to surface and subsurface runoff, a third component, being groundwater, is contributing in runoff. As only information about the total runoff at the catchment outlet is available, uncertainty exists about the contribution of the different flow processes. Agriculture is a main contributor of nutrients and sediments to surface water causing water quality problems. Knowledge about the different pathways of water and hence nutrients and sediments to open water systems is important with respect to the choice of mitigation measures in agricultural dominated catchments. Estimates of groundwater or baseflow contribution (BFI) are often based on the use of digital filters applied to average daily discharge values. When using recommended values for the digital filter, this resulted in BFI of 40 - 50 % when applied to small Norwegian agricultural catchments. When taking the poor natural drainage conditions into consideration in addition to the presence of heavy marine clay deposits at depths greater than 1 - 2 m below soil surface, these values are considered unrealistically high. Deelstra et al (2010) showed that small agricultural catchments can have rather "flashy" runoff behaviour, characterised by large diurnal variations in discharge which also contradicts high baseflow contributions. An approach to obtain a realistic filter parameter for a digital filter has been carried out, based on discharge measurements on a set of small, nested catchments in Norway and further tested in

  18. Linking Groundwater Nitrate-N Concentrations to Management and Hydrological Changes in two Agricultural Catchments

    NASA Astrophysics Data System (ADS)

    Mellander, Per-Erik; Melland, Alice R.; Jordan, Philip; Murphy, Paul N. C.; Shortle, Ger

    2013-04-01

    In order to minimize Nitrogen (N) transfer from groundwater to surface water in agricultural river catchments it is useful to understand how those transfer pathways may vary over time and space, and thus in their connection to nutrient sources and potential effects of temporal changes in water recharge and land management. In this paper we investigate the links between N sources, groundwater and surface water, as well as the implication of spatiotemporal variability for mitigation measures. We present three years of N concentrations in stream water (sub-hourly) and in groundwater (monthly) of different strata in four hillslopes in two ca 10 km2 Irish agricultural catchments with permeable soils. One catchment with arable land overlying slate bedrock and the other with intensively managed grassland on sandstone. Both catchments were dominated by delayed nutrient transfer pathways via groundwater. Relatively high concentrations of N were found in the groundwater of both catchments, attributed to leaching of surplus soil nitrate-N. The Grassland/sandstone catchment had locally higher nitrate-N concentrations in the groundwater with more spatiotemporal variability than in the groundwater of the Arable/Slate catchment. The N concentrations in the stream water of the Arable/Slate catchment were more directly reflected by groundwater conditions. In one hillslope the effects of pasture reseeding were observed by locally elevated N concentrations in the groundwater with a delay of ca five months. This was not reflected in the surface water despite groundwater dominating the contribution to stream water. In another hillslope N was naturally buffered in the near-stream zone, but this zone was bypassed with high nitrate-N content water from the uplands via tile-drains. The apparent spatiotemporal variability in N concentration highlights the need for insight into these differences when interpreting groundwater quality data from a limited number of sampling points and occasions

  19. Assessment of suspended matter transport in a large agricultural catchment using the MOHID water modelling system

    NASA Astrophysics Data System (ADS)

    David, Bailly; David, Brito; Chantha, Oeurng; Ramiro, Neves; Sabine, Sauvage; Sánchez-Pérez, José-Miguel

    2010-05-01

    Suspended sediment transport from agricultural catchments to stream networks is responsible for impaired water quality, reservoir sedimentation and the transport of sediment-bound pollutants (pesticides, particulate nutrients, metals and other adsorbed toxic substances). The dynamic of pollutants adsorbed on sediment and associated with particulate organic carbon, from land areas into stream network arises mainly from erosion and sedimentation processes. It is known that up to 90% of suspended sediment is transported during flood event and therefore quick flood events have a major impact on pollutant transport. This study - part of the EU AguaFlash (http://www.aguaflash-sudoe.eu/) project - examined and quantified suspended sediment dynamics from catchment to river (erosion, transport, deposition on hillside and in the river). Semi-distributed, physics-based watershed or reservoir models are generally used to simulate sediment dynamics. One of the limitations of this kind of modelling is that transport along agricultural field and the possibility of deposition of suspended sediments in hillslopes are not considered. Consequently, all sediments eroded are assumed to be accumulated in the river and the sediment and associated pollutant dynamics are over- or under-estimated. In our approach, the mechanistic physics-based water modelling system MOHID (http://www.mohid.com) was used to quantify soil erosion and sediment transport processes at the local and macroscopic scale. This paper present the erosion and transport mathematical model and modelling strategy used and compares our initial results with filed data obtained on an 1100 km² intensive agricultural catchment (Save catchment, South-west France) during 2007-2009 and with simulation data produced using SWAT (Soil and Water Assessment Tool, 2005 version). The contribution of the MOHID model compared with that of the semi-distributed SWAT model is discussed. Keywords: Erosion, suspended sediment, transport

  20. 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

  1. 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.

  2. Impact of agricultural practices and river catchment characteristics on river and bathing water quality.

    PubMed

    Aitken, M N

    2003-01-01

    The objective was to investigate the potential risk of faecal indicator organism (FIO) bacteriological contamination of river catchments and coastal bathing waters from farm management practices and to develop practices to reduce the risk. A risk assessment on 117 farms was carried out in two river catchments in south-west Scotland. Manure storage facilities, farming practices, field conditions and catchment characteristics were assessed. River samples at 33 locations were regularly taken and analysed for FIOs. Available manure storage capacity and farm management practices are inadequate on a high proportion of farms and FIO contamination of watercourses was likely the result of effluent transported into watercourses due to non-collection or poor containment. In addition, surface run-off or leaching following land application of manure or intensive stocking in adverse conditions was a high risk on up to 50% of farms. The concentrations of FIOs in the streams of two sub-catchments with high livestock intensity was 4 to 8 times higher compared to the two sub-catchments which had a low livestock intensity. The majority of potential risks of agricultural pollution to watercourses may be eliminated through improved manure and dirty water management, forward planning of manure spreading activities and improved operational procedures. PMID:15137173

  3. 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

  4. Bridging the Divide: understanding controls on nitrogen export by scaling from headwater catchments to eastern North America

    NASA Astrophysics Data System (ADS)

    Duncan, J. M.; Band, L. E.; Creed, I. F.; Duffy, C.; Green, M. B.; Groffman, P. M.; Tague, C.; Whittinghill, K. A.; Wollheim, W. M.

    2012-12-01

    A major challenge in ecohydrology is the development of a predictive understanding of the roles of land use and climate on nitrogen (N) cycling and export at regional to continental scales. A dramatic increase in anthropogenic N loads to terrestrial and aquatic ecosystems has contributed to forest decline, acidification of freshwater systems, and eutrophication of coastal and estuarine environments. Watershed studies have been a hallmark of ecosystem research and over the last few decades this approach has been refined to hierarchically link terrestrial and aquatic ecosystems as a continuum of water, carbon and nutrients along hydrologic flowpaths at multiple scales. We examine nested controls and feedbacks between biotic and abiotic processes controlling N cycling and export from watersheds within temperate forest biomes in eastern North America, a region that has undergone major changes in forest cover and structure as a result of historic logging, agricultural expansion then contraction, urbanization, N deposition, and climate change. Our conceptual model is that the controls on patterns of stream N concentrations and loads exported from watersheds emerge from a cascade of sources and sinks at multiple spatial and temporal scales that accumulate along converging flowpaths. This cascade integrates atmospheric, geologic, geomorphic, land use/land cover, water infrastructure and plant, soil and microbial responses. In order to synthesize controls at continental to patch (10-100 sq. m) scales, we must: (1) Understand how N is coupled to water and carbon cycling within reference forest ecosystems, broadly defined to including surface water drainage networks, across current climate, atmospheric N deposition, geologic, geomorphic and vegetation gradients; and (2) Develop a mechanistic understanding of how human activity alters the timing, magnitude and pattern of these coupled processes. Time series of N export patterns from long-term experimental watersheds across a

  5. Agricultural practices influence flow regimes of headwater streams in western Iowa.

    PubMed

    Tomer, M D; Meek, D W; Kramer, L A

    2005-01-01

    Agricultural tillage influences runoff and infiltration, but consequent effects on watershed hydrology are poorly documented. This study evaluated 25 yr (1971-1995) hydrologic records from four first-order watersheds in Iowa's loess hills. Two watersheds were under conventional tillage and two were under conservation (ridge) tillage, one of which was terraced. All four watersheds grew corn (Zea mays L.) every year. Flow-frequency statistics and autoregressive modeling were used to determine how conservation treatments influenced stream hydrology. The autoregressive modeling characterized variations in discharge, baseflow, and runoff at multi-year, annual, and shorter time scales. The ridge-tilled watershed (nonterraced) had 47% less runoff and 36% more baseflow than the conventional watershed of similar landform and slope. Recovery of baseflow after drought was quicker in the conservation watersheds, as evidenced by 365-d moving average plots, and 67% greater baseflow during the driest 2 yr. The two conventional watersheds were similar, except the steeper watershed discharged more runoff and baseflow during short (<30 d), wet periods. Significant multi-year and annual cycles occurred in all variables. Under ridge-till, seasonal (annual-cycle) variations in baseflow had greater amplitude, showing the seasonality of subsurface contaminant movement could increase under conservation practices. However, deviations from the modeled cycles of baseflow were also more persistent under conservation practices, indicating baseflow was more stable. Indeed, flow-frequency curves showed wet-weather discharge decreased and dry-weather discharge increased under conservation practices. Although mean discharge increased in the conservation watersheds, variance and skewness of daily values were smaller. Ridge tillage with or without terraces increased stream discharge but reduced its variability. PMID:16091607

  6. 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.

  7. 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. PMID:26849342

  8. Groundwater denitrification in two agricultural river catchments: influence of hydro-geological setting and aquifer geochemistry

    NASA Astrophysics Data System (ADS)

    McAleer, Eoin; Mellander, Per-Erik; Coxon, Catherine; Richards, Karl G.; Jahangir, Mohammad M. R.

    2015-04-01

    Identifying subsurface environments with a natural capacity for denitrification is important for improving agricultural management. At the catchment scale, a complex hierarchy of landscape, hydro-geological and physico-chemical characteristics combine to affect the distribution of groundwater nitrate (NO3-). This study was conducted along four instrumented hillslopes in two ca. 10km2 agricultural river catchments in Ireland, one dominated by arable and one by grassland agriculture. Both catchments are characterised by well drained soils, but have differing aquifer characteristics. The arable catchment is underlain by weathered Ordovician slate bedrock which is extensively fractured with depth. The grassland catchment is characterised by Devonian sandstone bedrock, exhibiting both lateral (from upslope to near stream) and vertical variations in permeability along each hillslope. The capacity for groundwater denitrification was assessed by examining the concentration and distribution patterns of N species (total nitrogen, nitrate, nitrite, ammonium), dissolved organic carbon (DOC), dissolved oxygen (DO) and redox potential (Eh) in monthly samples from shallow and deep groundwater piezometers (n=37). Additionally, the gaseous products of denitrification: nitrous oxide (N2O) and excess dinitrogen (excess N2) were measured seasonally using gas chromatography and membrane inlet mass spectroscopy, respectively. The slate catchment was characterised by uniformity, both laterally and vertically, in aquifer geochemistry and gaseous denitrification products. The four year spatial mean groundwater NO3--N concentration was 6.89 mg/l and exhibited low spatial and temporal variability (temporal SD: 1.19 mg/l, spatial SD: 1.185 mg/l). Elevated DO concentrations (mean: 9.75 mg/l) and positive Eh (mean: +176.5mV) at all sample horizons indicated a setting with little denitrification potential. This non-reducing environment was reflected in a low accumulation of denitrification

  9. Overland flow and sediment transport in an agricultural lowland catchments: a focus on tile drain export

    NASA Astrophysics Data System (ADS)

    Vandromme, Rosalie; Grangeon, Thomas; Cerdan, Olivier; Manière, Louis; Salvador Blanes, Sébastien; Foucher, Anthony; Chapalain, Marion; Evrard, Olivier; Le Gall, Marion

    2016-04-01

    Rural landscapes have been extensively modified by human activities in Western Europe since the beginning of the 20th century in order to intensify agricultural production. Cultivated areas often expanded at the expense of grassland and wetlands located in lowland areas (de Groot et al., 2002). Therefore, large modifications were made to the agricultural landscapes: stream redesign, land consolidation, removal of hedges, and installation of tile drainage networks to drain the hydromorphic soils. These changes modified sediment processes and resulted in large morphological alterations (e.g. channel bed incision, deposition of fine sediment, channel bank erosion). Accordingly, these alterations threaten water quality and prevent to meet the requirements of the European directives. Improving water quality requires a clear understanding of the hydrosedimentary dynamics in these lowland cultivated catchments. However, few studies were conducted in drained environments. To fill this research gap, a pilot study was started in cultivated catchment of the Loire River basin, France, where tile drain densities are very high (> 1.5 km/km²). Six hydro-sedimentary monitoring stations were installed in the Louroux catchment (24 km²). One of them was specifically dedicated to measuring water/sediment fluxes from tile drains. Water level and turbidity were continuously monitored and sediments were sampled during floods and low stage periods. Samples were measured for particle size distribution, and sediment tracing studies are currently being developed to quantify the contribution of potential sources (e.g. surface vs subsurface, lithologies) to river sediment. Hydro-sedimentary fluxes were quantified and modelled for some selected events. The catchment hydrosedimentary fluxes and their properties were shown to be impacted by tile drain sediment transport, especially regarding particle size distribution, with the dominant export of very fine particles (< 2 μm) from tile drains

  10. Distribution of soil organic carbon in two small agricultural Mediterranean catchments.

    NASA Astrophysics Data System (ADS)

    Gomez, J. A.; Burguet, M.; Taguas, M. E.; Perez, R.; Ayuso, J. L.; Vanwallgehem, T.; Giraldez, J. V.; Vanderlinden, K.

    2012-04-01

    Soil organic carbon (SOC) is a key indicator of soil quality and a major factor for evaluating carbon sequestration schemes in forest and agricultural soils. However, at the farm or catchment scale SOC presents a large spatial variability which complicates the evaluation of soil quality (Gomez et al., 2009) and the certification of the potential for carbon sequestration. We hypothesize that the typical row crop configuration of olive orchards, with cover crops or bare soil in-between the rows, can explain a vast proportion of this variability. However, it is also expected that agricultural activities and topography-driven erosion processes at different scales (Van Oost et al., 2007) will contribute to SOC variability. Given the complexity of this problem and the important experimental effort required to resolve it, there are to our knowledge relatively few studies that have addressed this issue, especially in agricultural soils under Mediterranean conditions. This communications presents a preliminary evaluation of the top 1-m SOC content at two small, 8 and 6.7-ha, catchments in Southern Spain, covered by olive groves, that were intensively sampled in 2011. Spatial variability of SOC is analyzed across tree rows, areas in-between tree rows, and at different depths. The SOC distribution is evaluated against the topography of the catchment and the intensity of the water erosion processes analyzed by a simple model, such as SEDD, as used by Ferro and Porto (2000) and Taguas et al. (2011). The results of this communication will explore and discuss the differences between both catchments, and suggest guidelines for further exploring the sources of SOC variability, while providing guidelines to improve SOC estimation at the field scale for certification purposes.

  11. Apportioning sediment pressures on watercourses in grassland dominated agricultural catchments: a new framework for policy support

    NASA Astrophysics Data System (ADS)

    Collins, A.; Black, K.; Walling, D. E.; Wilson, P.

    2009-04-01

    Much of the effort directed towards monitoring and understanding soil erosion in the UK has focused upon arable farming systems, but the evidence base has suggested for some time that soil loss from grassland dominated landscapes can be enhanced by agricultural practises. Studies using composite source fingerprinting procedures have, for example, repeatedly highlighted the relative significance of managed pasture as a sediment source at catchment scale. Although traditional sediment sourcing approaches provide useful generic information for characterising sediment pressures, Catchment Officers working as part of the England Catchment Sensitive Farming Delivery Initiative (ECSFDI) also require higher resolution evidence to assist better the targeting of mitigation options. Accordingly, a new framework combining conventional sediment source fingerprinting and a dual signature tracking method has recently been tested in a grassland catchment in Cumbria, north-west England. The former provides information on the relative significance of generic sediment sources such as grassland or arable surface soils, damaged road verges and channel banks/subsurface sources, whereas the latter elucidates sediment loss from poached gateways or cattle tracks and wider areas of general hoofing damage in grass fields. Uncertainty and prior information are explicitly recognised by the novel framework.

  12. 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 ...

  13. 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...

  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. Incidental nutrient transfers: Assessing critical times in agricultural catchments using high-resolution data.

    PubMed

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

    2016-05-15

    Managing incidental losses associated with liquid slurry applications during closed periods has significant cost and policy implications and the environmental data required to review such a measure are difficult to capture due to storm dependencies. Over four years (2010-2014) in five intensive agricultural catchments, this study used high-resolution total and total reactive phosphorus (TP and TRP), total oxidised nitrogen (TON) and suspended sediment (SS) concentrations with river discharge data to investigate the magnitude and timing of nutrient losses. A large dataset of storm events (defined as 90th percentile discharges), and associated flow-weighted mean (FWM) nutrient concentrations and TP/SS ratios, was used to indicate when losses were indicative of residual or incidental nutrient transfers. The beginning of the slurry closed period was reflective of incidental and residual transfers with high storm FWM P (TP and TRP) concentrations, with some catchments also showing elevated storm TP:SS ratios. This pattern diminished at the end of the closed period in all catchments. Total oxidised N behaved similarly to P during storms in the poorly drained catchments and revealed a long lag time in other catchments. Low storm FWM P concentrations and TP:SS ratios during the weeks following the closed period suggests that nutrients either weren't applied during this time (best times chosen) or that they were applied to less risky areas (best places chosen). For other periods such as late autumn and during wet summers, where storm FWM P concentrations and TP:SS ratios were high, it is recommended that an augmentation of farmer knowledge of soil drainage characteristics with local and detailed current and forecast soil moisture conditions will help to strengthen existing regulatory frameworks to avoid storm driven incidental nutrient transfers. PMID:26933967

  16. Field-based evaluation tool for riparian buffer zones in agricultural catchments.

    PubMed

    Ducros, Caroline M J; Joyce, Chris B

    2003-08-01

    Riparian buffer zones can improve water quality and enhance habitat, but a comprehensive yet rapid method that can assist the resource manager in assessing the effectiveness of buffers is not available. The aim of this paper is to describe and illustrate the use of a newly developed field-based evaluation tool for riparian buffer zones in agricultural catchments. The Buffer Zone Inventory and Evaluation Form (BZIEF) incorporates criteria-based scoring systems developed from literature review, subsequent peer-review, and then a pilot field study. Use of the BZIEF is demonstrated by comparing buffer zones in three catchments established for water quality and habitat improvement under the Water Fringe Option agrienvironment scheme in England in order to assess whether the buffers were likely to provide environmental enhancement. Results among the three catchments were generally similar; buffer zones scored highly for their abundant vegetation cover, lack of erosion, stream habitat quality, and sufficient width. Furthermore, previous grassland or arable land use did not substantially affect buffer zone ratings. However, the BZIEF indicated that inappropriate soil characteristics in one catchment were likely to constrain buffer zone effectiveness for improving water quality. In another catchment, poor riparian vegetation diversity and structure may yield ineffective habitat enhancement, according to the BZIEF. It was concluded that the BZIEF might be a useful tool for buffer zone comparison and monitoring, even though more work is needed to test and validate the method. For example, the BZIEF could be used to target appropriate locations for buffer zones and is flexible, so could be adapted for different policies, objectives and regions. PMID:14753650

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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.

    2009-04-01

    We study the surface and sub-surface hydrology of a small agricultural catchment (60ha) located in the Luang Prabang province of Lao PDR. This catchment is representative of the rural mountainous south east Asia. It exhibits steep slopes (up to 100% and more) under a monsoon climate. After years of traditional slash and burn cultures, it is now under high land pressures due to population resettling and environment preservation policies. This evolution leads to rapid land-use changes such as shifting cultivation reduction or growing of teak forest instead of classical crops. This catchment is a benchmark site of the Managing Soil Erosion Consortium since 1998. The international consortium aims to understand the effects of agricultural changes on the catchment hydrology and soil erosion in south east Asia. The Huay Pano catchment is subdivided into small sub-catchments that are gauged and monitored. Differ- ent agricultural practices where tested along the years. At a smaller scale, plot of 1m2 are instrumented to follow runoff and detachment of soil under natural rainfall along the monsoon season. Our modeling work aims to develop a distributed hydrological model integrating experimental data at the different scales. One of the objective is to understand the impact of land-use, soil properties (slope, crust, etc) and rainfall (dry and wet seasons) on surface and subsurface flows. We present here modeling results of the runoff plot experiments (1m2 scale) performed from 2002 to 2007. The plots distribution among the catchment and over the years gives a good representativity of the different runoff responses. The role of crust, slope and land-use on runoff is examined. Finally we discuss how this plot scale will be integrated in a sub-catchment model, with a particular attention on the observed paradox: how to explain that runoff coefficients at the catchment scale are much slower than at the plot scale ?

  3. 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.

  4. 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

  5. The effectiveness of agricultural stewardship for improving water quality at the catchment scale: Experiences from an NVZ and ECSFDI watershed

    NASA Astrophysics Data System (ADS)

    Kay, Paul; Grayson, Richard; Phillips, Martin; Stanley, Karen; Dodsworth, Alan; Hanson, Ann; Walker, Andrew; Foulger, Miles; McDonnell, Iain; Taylor, Simon

    2012-02-01

    SummaryAgriculture is estimated to be responsible for 70% of nitrate and 30-50% of phosphorus pollution, contributing to ecological and water treatment problems. Despite the fact that significant gaps remain in our understanding, it is known that agricultural stewardship can be highly effective in controlling water pollution at the plot and field scales. Knowledge at the catchment scale is, to a large extent, entirely lacking though and this is of paramount concern given that the catchment is the management unit used by regulatory authorities. The few studies that have examined the impact of agricultural stewardship at the catchment scale have found that Nitrate Vulnerable Zones (NVZs) in the UK have resulted in little improvement in water quality which concurs with the current catchment study. In addition to NVZs, there was little evidence to suggest that the England Catchment Sensitive Farming Delivery Initiative had impacted water quality and suggestions have been made for improvements, such as ensuring that stewardship measures are used in key pollution source areas and their implementation and impacts are monitored more closely. This will be essential if agricultural catchment management schemes are going to provide the benefits expected of them. Nevertheless, more intensive monitoring than that carried out by regulators showed a significant trend in decreasing winter nitrate peaks in some streams which is hypothesised to be due to recent reduced inorganic fertiliser application as a result of increasing prices. It was concluded that, collectively, these findings indicate that agricultural stewardship measures have the potential to improve water quality at the catchment scale but that voluntary schemes with insufficient financial reward or regulatory pressure are unlikely to be successful.

  6. 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

  7. 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

  8. 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. PMID:27074925

  9. A palaeolimnological investigation into nutrient impact and recovery in an agricultural catchment.

    PubMed

    O'Dwyer, Barry; Crockford, Lucy; Jordan, Phil; Hislop, Lindsay; Taylor, David

    2013-07-30

    Widespread deterioration in water quality as a result of anthropogenic activity has led to the development and implementation of measures aimed at the protection of water resources in the EU. To date, however, relatively little attention has been paid to the effectiveness of these measures. Evidence from an enrichment-sensitive lake permitted reconstructions of changes in ecological and chemical water quality over the last c. 150-200 years, a period that includes a mid to late 20th century intensification of agriculture that was widely experienced across the European Union and the subsequent implementation of measures aimed at protecting water resources against pollution from farming. The data show the development of a more nutrient-tolerant diatom community from early in the 20th century, while the main trophic changes occurred from the 1950s, with the site becoming eutrophic by the 1960s. Heightened enrichment is thought to be linked to enhanced levels of phosphorus (P) transfers from the surrounding grassland catchment owing to an intensification of agricultural activities locally. Most recently, since the late 1990s and particularly post-2007, evidence suggests a decrease in aquatic enrichment, despite continued increases in agricultural intensification. This decoupling is likely to mark a successful implementation in 2006 of measures aimed at decreasing diffuse nutrient transfers from catchments linked to agri-environmental policies in Europe. The research highlights the importance of enrichment-sensitive water bodies as sentinel sites in the monitoring of both external and internal nutrient loadings as agricultural activities and other pressures change within the context of implementing regulatory responses to earlier declines in water quality. PMID:23490624

  10. 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

  11. Impacts of the post-fire erosion processes compared with the agricultural erosion rates for a mountain catchment in NW Iberia

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Mediterranean ecosystems are very vulnerable to soil erosion by water due to particular characteristics of climate, lithology and land use history. Moreover, the foreseen climate changes might worsen land degradation and desertification, in which soil erosion has been classified as one of the most important driving forces. In this context, the frequent forest fires seen in some Mediterranean regions can case disturbances to vegetation cover and enhance soil erosion processes. This work addresses this issue for the Caramulo mountain range, NW Iberia. In the past century, large land use changes occurred due to massive afforestation. Changes from mixed natural forest cover and shrublands to Pine, the introduction of Eucalyptus plantations and, more recently, a trend for the substitution of pines by eucalypts, are the evidence of a large and rapid land use change in the last decades. Forest fires started to occur as afforestation proceeded, as a consequence of the disappearance of pasturage and accumulation of highly inflammable material; they became more frequent after the 1960's and became a determinant factor for land use changes in this region. Data collection focused on the Macieira de Alcoba catchment, a headwater agro-forested catchment (94 ha) located in this region. It has a wet Mediterranean climate, with an average annual rainfall of about 1300 mm (2002-2012), concentrated in autumn and winter, while spring and summer are dryer seasons. The mean annual temperature is 14°C and in summer it can reach 35°C. The land use is mixed, with forest and agriculture lands covering respectively 60 and 35% of the catchment area, 5% being built-up areas in the village of Macieira de Alcoba. In the last decades, this catchment suffered several forest fires (in 1969, 1986, 1991, and 2011). Erosion processes are related with periods of low vegetation cover in autumn in fields with a pasture-corn rotation, but also with forest plantations after clear-cutting and especially

  12. Deriving a per-field land use and land cover map in an agricultural mosaic catchment

    NASA Astrophysics Data System (ADS)

    Seo, B.; Bogner, C.; Poppenborg, P.; Martin, E.; Hoffmeister, M.; Jun, M.; Koellner, T.; Reineking, B.; Shope, C. L.; Tenhunen, J.

    2014-09-01

    Detailed data on land use and land cover constitute important information for Earth system models, environmental monitoring and ecosystem services research. Global land cover products are evolving rapidly; however, there is still a lack of information particularly for heterogeneous agricultural landscapes. We censused land use and land cover field by field in the agricultural mosaic catchment Haean in South Korea. We recorded the land cover types with additional information on agricultural practice. In this paper we introduce the data, their collection and the post-processing protocol. Furthermore, because it is important to quantitatively evaluate available land use and land cover products, we compared our data with the MODIS Land Cover Type product (MCD12Q1). During the studied period, a large portion of dry fields was converted to perennial crops. Compared to our data, the forested area was underrepresented and the agricultural area overrepresented in MCD12Q1. In addition, linear landscape elements such as waterbodies were missing in the MODIS product due to its coarse spatial resolution. The data presented here can be useful for earth science and ecosystem services research. The data are available at the public repository Pangaea (doi:110.1594/PANGAEA.823677).

  13. 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.

  14. 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

  15. Aquatic Community Colonization Within Riparian Headwater Corridors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Headwater streams are the smallest streams in a watershed. Their small size and high frequency of occurrence make them susceptible to anthropogenic habitat alterations. Many headwater streams in the Midwestern US have been channelized to drain agricultural fields. Aquatic macroinvertebrate communiti...

  16. Spatial and temporal dynamics of stream water particulate and dissolved N, P and C forms along a catchment transect, NE Scotland

    NASA Astrophysics Data System (ADS)

    Stutter, M. I.; Langan, S. J.; Cooper, R. J.

    2008-02-01

    SummaryThe dynamics of dissolved and particulate N, P and organic C were examined for field drains, through a headwater (4 km 2), into a mesoscale stream (51 km 2) and river (1844 km 2) catchment. Distributions of N and P forms were similar in the agricultural headwater and field drains; annual P fluxes of particulate and dissolved forms were of equal magnitude, whilst N was dominated by NO 3-N. Across all scales organic P was an important, often dominant, component of the dissolved P. Temporal variation in nutrient concentrations and proportions was greatest in the headwater, where storms resulted in the generation of large concentrations of suspended particulate matter, particulate and dissolved P, particularly following dry periods. The data suggest that groundwater and minor point source inputs to the mesoscale catchment buffered the temporal variability in hydrochemistry relative to the headwater. Summer low flows were associated with large PO 4-P concentrations in the mesoscale catchment at a critical time of biological sensitivity. At the largest river catchment scale, organic forms of C, N and P dominated. Inorganic nutrient concentrations were kept small through dilution by runoff from upland areas and biological processes converted dissolved N and P to particulate forms. The different processes operating between the drain/headwater to the large river scale have implications for river basin management. Given the prevalence of organic and particulate P forms in our catchment transect, the bioavailability of these fractions needs to be better understood.

  17. Predicting microbial water quality with models: Over-arching questions for managing risk in agricultural catchments.

    PubMed

    Oliver, David M; Porter, Kenneth D H; Pachepsky, Yakov A; Muirhead, Richard W; Reaney, Sim M; Coffey, Rory; Kay, David; Milledge, David G; Hong, Eunmi; Anthony, Steven G; Page, Trevor; Bloodworth, Jack W; Mellander, Per-Erik; Carbonneau, Patrice E; McGrane, Scott J; Quilliam, Richard S

    2016-02-15

    The application of models to predict concentrations of faecal indicator organisms (FIOs) in environmental systems plays an important role for guiding decision-making associated with the management of microbial water quality. In recent years there has been an increasing demand by policy-makers for models to help inform FIO dynamics in order to prioritise efforts for environmental and human-health protection. However, given the limited evidence-base on which FIO models are built relative to other agricultural pollutants (e.g. nutrients) it is imperative that the end-user expectations of FIO models are appropriately managed. In response, this commentary highlights four over-arching questions associated with: (i) model purpose; (ii) modelling approach; (iii) data availability; and (iv) model application, that must be considered as part of good practice prior to the deployment of any modelling approach to predict FIO behaviour in catchment systems. A series of short and longer-term research priorities are proposed in response to these questions in order to promote better model deployment in the field of catchment microbial dynamics. PMID:26657248

  18. Deriving a per-field land use and land cover map in an agricultural mosaic catchment

    NASA Astrophysics Data System (ADS)

    Seo, B.; Bogner, C.; Poppenborg, P.; Martin, E.; Hoffmeister, M.; Jun, M.; Koellner, T.; Reineking, B.; Shope, C. L.; Tenhunen, J.

    2014-04-01

    Detailed data on land use and land cover constitutes important information for Earth system models, environmental monitoring and ecosystem services research. Global land cover products are evolving rapidly, however, there is still a lack of information particularly for heterogeneous agricultural landscapes. We censused land use and land cover field by field in an agricultural mosaic catchment Haean, South Korea. We recorded the land cover types with additional information on agricultural practice and make this data available at the public repository Pangaea (doi:10.1594/PANGAEA.823677). In this paper we introduce the data, its collection and the post-processing protocol. During the studied period, a large portion of dry fields was converted to perennial crops. A comparison between our dataset and MODIS Land Cover Type (MCD12Q1) suggested that the MODIS product was restricted in this area since it does not distinguish irrigated fields from general croplands. In addition, linear landscape elements such as water bodies were not detected in the MODIS product due to its coarse spatial resolution. The data presented here can be useful for earth science and ecosystem services research.

  19. Evaluating the ability of grass filter strips to contribute to the restoration of degraded agricultural headwater streams in central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grass filter strips are planted adjacent to agricultural streams in the United States as riparian buffers to reduce nutrient, pesticide, and sediment input into streams. This frequently used agricultural conservation practice is assumed to have the ability to mitigate the effects of agriculture on s...

  20. 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

  1. Modelling the impact of prescribed global warming on water resources of headwater catchments of the Irrawaddy River and their implications for Loktak Lake, northeast India

    NASA Astrophysics Data System (ADS)

    Singh, C. R.; Thompson, J. R.; French, J. R.; Kingston, D. G.; Mackay, A. W.

    2010-05-01

    Climate change is likely to have major implications for wetland ecosystems, which will include altered water level regimes due to modifications in local and catchment hydrology. However, substantial uncertainty exists in the precise impacts of climate change on wetlands due in part due to uncertainty in GCM projections. This paper explores the impacts of climate change upon river discharge within three sub-catchments of Loktak Lake, an internationally important wetland in northeast India. This is achieved by running pattern-scaled GCM output through distributed hydrological models (developed using MIKE SHE) of each sub-catchment. The impacts of climate change upon water levels within Loktak Lake are subsequently investigated using a water balance model. Two groups of climate change scenarios are investigated. Group 1 uses results from seven different GCMs for an increase in global mean temperature of 2 °C, the purported threshold of "dangerous" climate change, whilst Group 2 is based on results from the HadCM3 GCM for increases in global mean temperature between 1 °C and 6 °C. Results from the Group 1 scenarios show varying responses between the three sub-catchments. The majority of scenario-sub-catchment combinations (13 out of 21) indicate increases in discharge which vary from <1% to 42% although, in some cases, discharge decreases by as much as 20%. Six of the GCMs suggest overall increases in river flow to Loktak Lake (2-27%) whilst the other results in a modest (6%) decline. In contrast, the Group 2 scenarios lead to an almost linear increase in total river flow to Loktak Lake with increasing temperature (up to 27% for 6 °C), although two sub-catchments experience reductions in mean discharge for the smallest temperature increases. In all but one Group 1 scenario, and all the Group 2 scenarios, Loktak Lake water levels are higher, regularly reaching the top of a downstream hydropower barrage that impounds the lake and necessitating the release of water

  2. Re-examining the basis for source discrimination and data corrections used by sediment fingerprinting studies in agricultural catchments

    NASA Astrophysics Data System (ADS)

    Smith, Hugh; Blake, Will

    2014-05-01

    The sediment fingerprinting technique has been widely used in agricultural catchments to quantify fine sediment contributions from various land use sources. This application of the technique depends on the key assumption that land-use source signatures imprinted on catchment soils are decipherable from those due to other landscape factors affecting soil and sediment properties. We re-examine this key assumption by investigating (i) the physical and chemical basis for source discrimination and (ii) potential factors that may confound source un-mixing in agricultural catchments, including particle size and organic matter effects on tracer properties. The study is situated in the River Tamar, a predominantly agricultural catchment in south-west England that has also been affected by mining. Source discrimination focused on pasture and cultivated land uses and channel banks. Monthly, time-integrated suspended sediment samples were collected across seven catchments for a 12-month period. Physical and chemical properties measured in source soils and sediment included fallout radionuclides, major and minor element geochemical constituents, total organic carbon and particle size. Source discrimination was entirely dependent on differences in tracer property concentrations between surface and sub-surface soils. This is based on fallout radionuclide concentrations that are surface-elevated, while many geochemical properties are surface-depleted due to weathering and pedogenetic effects, although surface soil contamination can reverse this trend. Source discrimination in the study catchments was limited by (i) rotation of cultivated and pasture fields resulting in reduced differences between these two sources and (ii) the cultivated source signature resembling a mix of the pasture and channel bank sources for many tracer properties. Furthermore, metal pollution from abandoned historic mines and organic enrichment of sediment from areas of peaty soil resulted in the non

  3. 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...

  4. Dynamics of nitrate and chloride during storm events in agricultural catchments with different subsurface drainage intensity (Indiana, USA)

    NASA Astrophysics Data System (ADS)

    Kennedy, Casey D.; Bataille, Clement; Liu, Zhongfang; Ale, Srinivasulu; VanDeVelde, Justin; Roswell, Charles R.; Bowling, Laura C.; Bowen, Gabriel J.

    2012-10-01

    SummaryDrainage tiles buried beneath many naturally poorly drained agricultural fields in the Midwestern U.S. are believed to "short circuit" pools of NO3--laden soil water and shallow groundwater directly into streams that eventually discharge to the Mississippi River. Although much is known about the mechanisms controlling this regionally pervasive practice of artificial drainage at the field-plot scale, an integrative assessment of the effect of drainage density (i.e., the number of tile drains per unit area) on the transport of nutrients and solutes in streams at the catchment scale is lacking. In this study, we quantified the flux and hydrological pathways of agricultural NO3- and road-salt Cl- from catchments lying within the Wabash River Basin, a major source of NO3- to the Mississippi River. The paired catchments differ primarily in drainage density (70% vs. 31%, by catchment area), with essentially all other agricultural management, land use, and soil drainage characteristics remaining equal. Our study revealed two significant hydrological responses to increased drainage density: (1) more near-surface storm event water (dilute in both NO3- and Cl) was transported early in the storm and (2) higher transport of Cl--laden pre-event soil water relative to shallow groundwater elevated in NO3- occurred later in the storm. These patterns are consistent with a proposed conceptual model in which increased drainage density results in (1) greater transport of soil water to streams and (2) a delayed rise in the water table. With respect to nutrient management implications, these results indicate that increased drainage density impacts subsurface pools of Cl- and NO3- differently, a finding that we propose is linked to soil/ground water dynamics in artificially drained agricultural catchments.

  5. 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

  6. 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. PMID:26789373

  7. A Lowland Catchment Response to Heavy Agricultural Nitrogen Loads Explained with a Multiple Isotope and Hydrochemical Approach

    NASA Astrophysics Data System (ADS)

    Wexler, S. K.; Hiscock, K. M.; Dennis, P.

    2009-12-01

    East Anglia, UK, is a lowland area of intensive agriculture, producing much of the UK’s arable crops, while also supporting some of Europe’s most sensitive wetland habitats. The River Wensum in East Anglia is a calcareous lowland river with Site of Special Scientific Interest status. Within the catchment Special Areas of Conservation have been designated (EU Habitats Directive). The river supplies the city of Norwich with its drinking water (population 120 000), while downstream of Norwich water from the Wensum flows through the Norfolk Broads, a unique and protected wetland habitat, to enter the North Sea at Great Yarmouth. The Wensum catchment, covering an area of 570 km2, is heavily impacted by agricultural activity with a high nutrient load that affects both the underlying Cretaceous Chalk aquifer and the groundwater-dependent river, which has a base flow index of 0.78. Nitrate concentrations exceed the legal limit in places (up to 85 mg/ L). In this study, river, tributary, drain and groundwater samples from the Wensum catchment were collected over 27 months from February 2007, through all seasons and flow conditions, alongside samples of fertiliser, manure, waste water, precipitation and dry deposition. The nitrogen and oxygen isotopic composition of nitrate was analysed using the denitrifier method to understand nitrogen transport and cycling within the catchment. Water isotopes were used as an additional tracer, with major ion and trace element hydrochemistry. There is evidence of significant natural attenuation of nitrate which occurs in different locations and at varying rates within the catchment hydrology. Baseflow from highly impacted Chalk groundwater in the valley, with the lowest nitrate isotope ratios and highest concentration of catchment waters, is partially denitrified as it passes through a thick gravel hyporheic zone. Nitrate in surface drainage water undergoes assimilation and denitrification as it infiltrates through the soil and

  8. 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

  9. 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. PMID:26196068

  10. 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

  11. 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

  12. DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths - are DOC exports mediated by iron reduction/oxidation cycles?

    NASA Astrophysics Data System (ADS)

    Knorr, K.-H.

    2013-02-01

    Dissolved organic carbon (DOC) exports from many catchments in Europe and North-America are steadily increasing. Several studies have sought to explain this observation. As possible causes, a decrease in acid rain or sulfate deposition, concomitant reductions in ionic strength and increasing temperatures were identified. DOC often originates from riparian wetlands; but here, despite higher DOC concentrations, ionic strength in pore waters usually exceeds that in surface waters. In the catchment under study, DOC concentrations were synchronous with dissolved iron concentrations in pore and stream water. This study aims at testing the hypothesis that DOC exports are mediated by iron reduction/oxidation cycles. Following the observed hydrographs, δ18O of water and DOC fluorescence, the wetlands were identified as the main source of DOC. Antecedent biogeochemical conditions, i.e., water table levels in the wetlands, influenced the discharge patterns of nitrate, iron and DOC during an event. The correlation of DOC with pH was positive in pore waters, but negative in surface waters; it was negative for DOC with sulfate in pore waters, but only weak in surface waters. Though, the positive correlation of DOC with iron was universal for pore and surface water. The decline of DOC and iron concentrations in transition from anoxic wetland pore water to oxic stream water suggests a flocculation of DOC with oxidising iron, leading to a drop in pH in the stream during high DOC fluxes. The pore water did not per se differ in pH. There is, thus, a need to consider processes more thoroughly of DOC mobilisation in wetlands when interpreting DOC exports from catchments. The coupling of DOC with iron fluxes suggested that increased DOC exports could at least, in part, be caused by increasing activities in iron reduction, possibly due to increases in temperature, increasing wetness of riparian wetlands, or by a shift from sulfate dominated to iron reduction dominated biogeochemical

  13. DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths - are DOC exports mediated by iron reduction/oxidation cycles?

    NASA Astrophysics Data System (ADS)

    Knorr, K.-H.

    2012-09-01

    Dissolved organic carbon (DOC) exports from many catchments in Europe and North-America are steadily increasing. Several studies have sought to explain this observation. As possible causes, a decrease in acid rain or sulfate deposition, concomitant reductions in ionic strength and increasing temperatures were identified. DOC often originates from riparian wetlands; but here, despite higher DOC concentrations, ionic strength in pore waters usually exceeds that in surface waters. In the catchment under study, DOC concentrations were synchronous with dissolved iron concentrations in pore and stream water. This study aims at testing the hypothesis that DOC exports are mediated by iron reduction/oxidation cycles. Following the observed hydrographs, δ18O of water, and DOC fluorescence, the wetlands were identified as main source of DOC. Antecedent biogeochemical conditions, i.e. water table levels in the wetlands, influenced the discharge patterns of nitrate, iron, and DOC during an event. The correlation of DOC with pH was positive in pore waters but negative in surface waters; it was negative for DOC with sulfate in pore waters but only weak in surface waters. The positive correlation of DOC with iron was universal for pore and surface water, though. The decline of DOC and iron concentrations in transition from anoxic wetland pore water to oxic stream water suggests a flocculation of DOC with oxidizing iron, leading to a drop in pH in the stream during high DOC fluxes. The pore water did not per se differ in pH. There is thus a need to more thoroughly consider processes of DOC mobilization in wetlands when interpreting DOC exports from catchments. The coupling of DOC with iron fluxes suggested that increased DOC exports could at least in part be caused by increasing activities in iron reduction, possibly due to increases in temperature or wetness of riparian wetlands.

  14. Suspended sediment export in five intensive agricultural river catchments with contrasting land use and soil drainage characteristics

    NASA Astrophysics Data System (ADS)

    Sherriff, Sophie; Rowan, John; Melland, Alice; Jordan, Phil; Fenton, Owen; hUallacháin, Daire Ó.

    2015-04-01

    Soil erosion and sediment loss from land can have a negative impact on the chemical and ecological quality of freshwater resources. In catchments dominated by agriculture, prediction of soil erosion risk is complex due to the interaction of physical characteristics such as topography, soil erodibility, hydrological connectivity and climate. Robust measurement approaches facilitate the assessment of sediment loss magnitudes in relation to a range of agricultural settings. These approaches improve our understanding of critical sediment transfer periods and inform development of evidence-based and cost-effective management strategies. The aim of this study was to i) assess the efficacy of out-of-channel (ex-situ) suspended sediment measurement approaches, ii) to quantify the variability of sediment exported from five river catchments with varying hydrology and agricultural land uses over multiple years and iii) to investigate trends in relation to physical and land use characteristics when sediment data were compared between catchments. Sediment data were collected in five intensive agricultural river catchments in Ireland (3-11 km2) which featured contrasting land uses (predominantly intensive grassland or arable) and soil drainage classes (well, moderate and poor). High-resolution suspended sediment concentration data (SSC - using a calibrated turbidity proxy) were collected ex-situ and combined with in-stream discharge data measured at each catchment outlet to estimate suspended sediment yield (SSY - t km-2 yr-1). In two catchments additional in-stream turbidity monitoring equipment replicated ex-situ measurements including site specific calibration of individual in-stream and ex-situ turbidity probes. Depth-integrated samples were collected to assess the accuracy of both approaches. Method comparison results showed that true SSC values (from depth-integrated sampling) were predominantly within the 95% confidence interval of ex-situ predicted SSC consequently

  15. 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)

  16. 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...

  17. Impacts of agricultural phosphorus use in catchments on shallow lake water quality: About buffers, time delays and equilibria.

    PubMed

    Schippers, Peter; van de Weerd, Hendrika; de Klein, Jeroen; de Jong, Barend; Scheffer, Marten

    2006-10-01

    Phosphorus (P) losses caused by intensive agriculture are known to have potentially large negative effects on the water quality of lakes. However, due to the buffering capacity of soils and lake ecosystems, such effects may appear long after intensive agriculture started. Here we present the study of a coupled shallow lake catchment model, which allows a glimpse of the magnitude of these buffer-related time delays. Results show that the buffering capacity of the lake water was negligible whereas buffering in the lake sediment postponed the final lake equilibrium for several decades. The surface soil layer in contact with runoff water was accountable for a delay of 5-50 years. The most important buffer, however, was the percolation soil layer that may cause a delay of 150-1700 years depending on agricultural P surplus levels. Although the buffers could postpone final lake equilibria for a considerable time, current and target agricultural surplus levels eventually led to very turbid conditions with total P concentrations of 2.0 and 0.6 mg L(-1) respectively. To secure permanent clear water states the current agricultural P surplus of 15 kg P ha(-1) yr(-1) should drop to 0.7 kg P ha(-1) yr(-1). We present several simple equations that can be used to estimate the sustainable P surplus levels, buffer related time delays and equilibrium P concentrations in other catchment-lake systems. PMID:16781763

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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

  3. Monitoring of soil moisture dynamics and spatial differences in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Oswald, Sascha; Baroni, Gabriele; Biro, Peter; Schrön, Martin

    2015-04-01

    A novel method to observe changes in soil moisture and other water pools at the land surface is non-invasive cosmic-ray neutron sensing. This approach by its physical principles is placed between in-soil measurements and remote sensing, and retrieves values for an intermediate spatial scale of several hectars, which can be used to quantify stored water at the land surface. It detects variations in the background of neutrons, induced initially from cosmic-rays hitting the atmosphere, and this can be related to interesting quantities at the land surface, such as soil moisture, but to some degree also snow water equivalent and changes in the biomass of vegetation. In a small catchment being used as a long-term landscape observatory of the TERENO initiative we retrieved cosmic-ray neutron measurements for several years, for up to four adjacent sites. The terrain was hilly with some slopes being partly used for agricultural fields, partly grassland. Here, after atmospheric corrections and a calibration procedure soil moisture dynamics could be observed for integral soil depths of several decimeters, clearly responding to precipitation events and offering a comparison to various local and non-local soil moisture measurements there. For winter periods with frost and snow, also the water mass stored in the snow cover can be retrieved. Furthermore, observed spatial differences can be related to vegetation, terrain and soil moisture state. Also, the relation to parameters representing crop biomass and growth will be discussed in respect to the retrieved cosmic-ray neutron signals, which have an influence on the interpretation as soil moisture.

  4. Impacts of intensive agricultural irrigation and livestock farming on a semi-arid Mediterranean catchment.

    PubMed

    Martín-Queller, Emi; Moreno-Mateos, David; Pedrocchi, César; Cervantes, Juan; Martínez, Gonzalo

    2010-08-01

    Irrigation return flows (IRF) are a major contributor of non-point source pollution to surface and groundwater. We evaluated the effects of irrigation on stream hydrochemistry in a Mediterranean semi-arid catchment (Flumen River, NE Spain). The Flumen River was separated into two zones based on the intensity of irrigation activities in the watershed. General linear models were used to compare the two zones. Relevant covariables (urban sewage, pig farming, and gypsum deposits in the basin) were quantified with the help of geographic information system techniques, accompanied by ground-truthing. High variability of the water quality parameters and temporal dynamics caused by irrigation were used to distinguish the two river reaches. Urban activity and livestock farming had a significant effect on water chemistry. An increase in the concentration of salts (240-541 microS.cm(-1) more in winter) and nitrate (average concentrations increased from 8.5 to 20.8 mg.l(-1) during irrigation months) was associated with a higher level of IRF. Those river reaches more strongly influenced by urban areas tended to have higher phosphorus (0.19-0.42 mg.l(-1) more in winter) concentrations. These results support earlier research about the significant consequences to water quality of both urban expansion and intensive agricultural production in arid and semi-arid regions. Data also indicate that salinization of soils, subsoils, surface water, and groundwater can be an unwelcome result of the application of pig manure for fertilization (increase in sodium concentration in 77.9 to 138.6 mg.l(-1)). PMID:19585246

  5. 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...

  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. PMID:24718675

  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 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

  9. Transport of suspended sediment and organic carbon during storm events in a large agricultural catchment, southwest France.

    NASA Astrophysics Data System (ADS)

    Chantha, Oeurng; Sabine, Sauvage; David, Baqué; Alexandra, Coynel; Eric, Maneux; Henri, Etcheber; José-Miguel, Sánchez-Pérez

    2010-05-01

    Intensive agriculture has led to environmental degradation through soil erosion and carbon loss transferred from agricultural land to the stream networks. Suspended sediment transport from the agricultural catchment to the watercourses is responsible for aquatic habitat degradation, reservoir sedimentation, and for transporting sediment associated pollutants (pesticides, nutrient, heavy metals and other toxic substances). Consequently, the temporal transport of suspended sediment (SS), dissolved and particulate organic carbon (DOC and POC) was investigated during 18 months from January 2008 to June 2009 within a large agricultural catchment in southwest France. This study is based on an extensive dataset with high temporal resolution using manual and automatic sampling, especially during 15 flood events. Two main objectives aim at: (i) studying temporal transport in suspended sediment (SS), DOC and POC with factors explaining their dynamics and (ii) analysing the relationships between discharge, SSC, DOC and POC during flood events. The study demonstrates there is a strong variability of SS, POC and DOC during flood events. The SS transport during different seasonal floods varied by event from 513 to 41 750 t; POC transport varied from 12 to 748 t and DOC transport varied from 9 to 218 t. The specific yield of the catchment represents 76 t km-2 y-1 of sediment, 1.8 t km-2 y-1 of POC and 0.7 t km-2 y-1 of DOC, respectively. The POC associated with sediment transport from the catchment accounted for ~2.5% of the total sediment load. Flood duration and flood magnitude are key factors in determining the sediment and organic carbon transport. Statistical analyses revealed strong correlations between total precipitation, flood discharge, total water yield with suspended sediment and organic transport. The relationships of SSC, POC and DOC versus discharge over temporal flood events resulted in different hysteresis patterns which were used to suggest those dissolved and

  10. IDENTIFICATION OF PREDOMINANT ENVIRONMENTAL FACTORS STRUCTURING STREAM MACROINVERTEBRATE COMMUNITIES WITHIN A LARGE AGRICULTURAL CATCHMENT

    EPA Science Inventory

    Patterns of macroinvertebrate community composition were examined in streams within a 40,000-km2 catchment in central Michigan, USA, to identify the major environmental gradients influencing community variation. griculture and associated clay and sandy soils predominated in much ...

  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. 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.

  13. 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

  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. 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. PMID:23830922

  17. Assessment of hydrology, suspended sediment and particulate organic carbon transport in a large agricultural catchment using SWAT model

    NASA Astrophysics Data System (ADS)

    Chantha, Oeurng; Sabine, Sauvage; José-Miguel, Sánchez-Pérez

    2010-05-01

    Suspended sediment transport from agricultural catchments to stream networks is responsible for aquatic habitat degradation, reservoir sedimentation and the transport of sediment-bound pollutants (pesticides, particulate nutrients, heavy metals and other toxic substances). Quantifying and understanding the dynamics of suspended sediment transfer from agricultural land to watercourses is essential in controlling soil erosion and in implementing appropriate mitigation practices to reduce stream suspended sediment and associated pollutant loads, and hence improve surface water quality downstream. Gascogne area, southwest France, has been dominated by anthropogenic activities particularly intensive agriculture causing severe erosion in recent decades. This leads to a major threat to surface water quality due to soil erosion. Therefore, the catchment water quality has been continuously monitored since January 2007 and the historical data of hydrology and suspended sediment has existed since 1998. In this study, the Soil and Water Assessment Tool (SWAT 2005) was applied to assess hydrology, suspended sediment and particulate organic carbon in this catchment Agricultural management practices (crop rotation, planting date, fertilizer quantity and irrigations) were taken into the model for simulation period of 11 years (July, 1998 to March, 2009). The investigation was conducted using a 11-year streamflow and two years of suspended sediment record from January 2007 to March 2009. Modelling strategy with dominant landuse and soil type was chosen in this study. The SWAT generally performs satisfactorily and could simulate both daily and monthly runoff and sediment yield. The simulated daily and monthly runoff matched the observed values satisfactorily (ENash>0.5). For suspended sediment simulation, the simulated values were compared with the observed continuous suspended sediment derived from turbidity data. Based on the relationship between SSC and POC (R2 = 0.93), POC was

  18. 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

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

    PubMed

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

    2002-10-01

    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. PMID:12389788

  20. Using the Provenance of Sediment and Bioavailable Phosphorus to Help Mitigate Water Quality Impact in an Agricultural Catchment.

    PubMed

    McDowell, R W; Norris, M; Cox, N

    2016-07-01

    The quality and health of surface waters can be impaired by sediment and sediment-bound phosphorus (P). The Waituna Lagoon catchment in southern New Zealand has undergone agricultural intensification that has been linked to increases in sediment and sediment-bound bioavailable P (BAP) in the lagoon. Time-integrated samplers trapped suspended sediment from the water column, and their geochemical signature was compared with likely sources (stream banks, stream beds, topsoil, and subsoil) in each of the lagoon's contributing streams and rivers. The proportion of BAP, but not necessarily total P, within trapped sediment was much greater in samples from the Moffat and Carran Creeks than from the Waituna Creek, probably due to the erosion of organic-rich soils that had little capacity to retain P compared with the more mineral soils of the Waituna Creek. Annually, most BAP and sediment came from bank erosion, and strategies such as fencing out stock should focus on minimizing this throughout the catchment. However, when considering losses in space and time relative to the impact on the Waituna Lagoon, strategies the Waituna Creek catchment should also minimize contributions from topsoil in winter-spring, whereas in the Carran and Moffat Creek catchments strategies need to decrease P inputs (e.g., effluent) to Organic soils likely to lose much BAP in summer-autumn when the impact on the Lagoon is quickest. This study highlighted the need to identify sources and timings of BAP and sediment loss before recommending mitigation practices, which without this information may be slow or not succeed. PMID:27380076

  1. 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.

  2. Scale appropriate modelling to represent dominant pollution processes in agricultural catchments, to underpin management and policy decisions

    NASA Astrophysics Data System (ADS)

    Adams, Russell; Quinn, Paul

    2014-05-01

    We present the development of scale appropriate modelling techniques to represent dominant pollution processes in agricultural catchments to underpin catchment management and its implications on policy. A quasi-physically based, spatially lumped macro-model (CRAFT), has been developed to assess mitigation options for nitrogen and phosphorus. CRAFT has been developed to use daily time series data of rainfall, stream flow and nutrient concentration data, and can be applied to catchments varying in size from a few hectares to 100s of square kilometres. If stream flow routing is added to the model then potentially larger catchments and sub-daily time steps could be represented. There are two key issues addressed here. Firstly, the model can be used to assess the usefulness of monitoring data collected at a high temporal resolution at considerable expense compared to routine grab sampling. An earlier study in the Frome catchment in southern England collected sub-daily water quality data for more than 12 months at the catchment outlet, comprising: total oxidised nitrogen (TON); soluble reactive phosphorus (SRP) and total phosphorus (TP) concentrations. The three data sets have quite different temporal signals relating to flow pathways with different residence times and the importance of runoff events in generating acute pollution. The flexible model structure was therefore developed to include different sources of runoff including overland flow from impervious areas in the catchment, where pollution hotspots will be located (e.g. farmyards). The model has been used to assess the value of collecting high resolution monitoring data, in this case by resampling the Frome sub-daily data to a daily timestep, and comparing these model simulations against those calibrated using all the samples. The usefulness of the high resolution data can be assessed on whether a daily model would undepredict (for example) high nutrient concentrations that can be identified in the sub

  3. 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

  4. SUSTAINABLE AGRICULTURE FOR THE WATER CATCHMENT PROTECTION AREA IN NTISAW, CAMEROON

    EPA Science Inventory

    We expect that the catchment area will increase food output for the community in addition to preserving the water source. Increased food output will benefit needy residents and allow them to focus more on education and economic development. Additionally, an area of sustainable...

  5. Spatial heterogeneity of mobilization processes and input pathways of herbicides into a brook in a small agricultural catchment

    NASA Astrophysics Data System (ADS)

    Doppler, Tobias; Lück, Alfred; Popow, Gabriel; Strahm, Ivo; Winiger, Luca; Gaj, Marcel; Singer, Heinz; Stamm, Christian

    2010-05-01

    Soil applied herbicides can be transported from their point of application (agricultural field) to surface waters during rain events. There they can have harmful effects on aquatic species. Since the spatial distribution of mobilization and transport processes is very heterogeneous, the contributions of different fields to the total load in a surface water body may differ considerably. The localization of especially critical areas (contributing areas) can help to efficiently minimize herbicide inputs to surface waters. An agricultural field becomes a contributing area when three conditions are met: 1) herbicides are applied, 2) herbicides are mobilized on the field and 3) the mobilized herbicides are transported rapidly to the surface water. In spring 2009, a controlled herbicide application was performed on corn fields in a small (ca 1 km2) catchment with intensive crop production in the Swiss plateau. Subsequently water samples were taken at different locations in the catchment with a high temporal resolution during rain events. We observed both saturation excess and hortonian overland flow during the field campaign. Both can be important mobilization processes depending on the intensity and quantity of the rain. This can lead to different contributing areas during different types of rain events. We will show data on the spatial distribution of herbicide loads during different types of rain events. Also the connectivity of the fields with the brook is spatially heterogeneous. Most of the fields are disconnected from the brook by internal sinks in the catchment, which prevents surface runoff from entering the brook directly. Surface runoff from these disconnected areas can only enter the brook rapidly via macropore-flow into tile drains beneath the internal sinks or via direct shortcuts to the drainage system (maintenance manholes, farmyard or road drains). We will show spatially distributed data on herbicide concentration in purely subsurface systems which shows

  6. Flood survey of nitrate behaviour using nitrogen isotope tracing in the critical zone of a French agricultural catchment

    NASA Astrophysics Data System (ADS)

    Paul, Alexia; Moussa, Issam; Payre, Virginie; Probst, Anne; Probst, Jean-Luc

    2015-11-01

    Measurements of δ15N-NO3- were taken in a highly flood-responsive agricultural catchment in the southwest of France to trace the sources and transfer pathways of nitrates during flood events. From January to March 2013, surface water samples were collected every week at the outlet, and four floods were sampled with a high resolution. Sampling was also performed in surface waters and sand lenses from the rest of the basin to trace nitrate sources and processes spatially. Nitrate extractions were performed using a method based on the solubility difference between inorganic salts and organic solutions. The δ15N values were in the range of surface water contaminated by N-fertilisers. Depending on the hydroclimatic event, nitrates resulted from a combination of sources and processes. At the start of the floods, the values of δ15N-NO3- and nitrate concentrations were low, demonstrating the dilution of water with rainwater. During a second phase, the nitrate concentration and the δ15N were higher. Deeper waters and soil solutions were the second source of nitrates. When the water level was low, both nitrate concentration and isotopic composition were high. These values reflected the denitrification processes that occurred in the soil under anaerobic conditions. An analysis of δ15N-NO3- in stream water in a small agricultural catchment was efficient at determining the origin of nitrates during flood events using a simple method.

  7. Establishing a sediment budget for a small agricultural catchment in southern Brazil, to support the development of effective sediment management strategies

    NASA Astrophysics Data System (ADS)

    Minella, Jean P. G.; Walling, Desmond E.; Merten, Gustavo H.

    2014-11-01

    The rapid expansion of agriculture in Brazil has increased erosion rates and sediment yields, causing many negative environmental and economic impacts, both on- and off-site. However, to date, very few catchment-scale sediment budget investigations have been carried out in Brazil. Given the need to reduce the negative off-site impacts of increasing agricultural activity, there is an important need for such investigations in order to inform the development of effective sediment management strategies. Against this background, 137Cs measurements have been combined with measurements of sediment yield and fingerprinting the source of the fine sediment output, to establish a provisional sediment budget for a small (1.19 km2) agricultural catchment in southern Brazil. The catchment is located in an area of steep highly erodible basaltic terrain, which has been intensively cultivated with tobacco. An ongoing monitoring programme provided information on the sediment yield from the catchment and existing suspended sediment source fingerprinting investigations provided information on the main sediment sources contributing to the sediment load at the catchment outlet. 137Cs measurements have been used to estimate medium-term erosion and deposition rates along 17 transects across the cultivated slopes and to quantify sedimentation rates within valley floor sediment sinks. These data have been used to estimate sediment redistribution rates within the cultivated areas of the study catchment and sediment accumulation in the valley floor sinks. The information provided by the three primary data sources has been integrated to establish the sediment budget for the catchment over the past 57 years. The individual terms of the budget necessarily involve much uncertainty, but its closure adds confidence to the final result. The budget calculations indicate that the study catchment has a sediment delivery ratio of ∼15%. The implications of the key features of the budget for developing

  8. 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

  9. 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

  10. Spatio-temporal variability of shallow groundwater quality in a typical agricultural catchment in subtropical central China

    NASA Astrophysics Data System (ADS)

    Liu, X.

    2015-12-01

    Excessive agriculture-sourced N leaching into shallow groundwater has deteriorated the domestic water quality in rural China. To effectively prevent the above environmental contamination issue, it is an essential prerequisite of exploring the spatio-temporal variability (stV) of the groundwater quality. In this study, a large observation program was deployed to observe ammonium-N (NH4N), nitrate-N (NO3N) and total N (TN) concentrations in 194 groundwater observation wells (1.5 m deep from soil surface) from April 2010 to November 2012 in the Jinjing river catchment in Hunan Province of China. A logit function was applied to transform NH4N, NO3N and TN data for normality; the resultant variables were thus named as NH4Nt, NO3Nt and TNt, respectively. A spatio-temporal semivariogram model in a sum-metric form was used to quantify the stV of NH4Nt, NO3Nt and TNt. The results indicated that the 33-month means ± standard deviations of the NH4N, NO3N and TN concentrations were 0.75±0.10, 1.60±0.19 and 2.99±0.29 mg N L-1, respectively. NH4Nt and NO3Nt exhibited a strong spatio-temporal dependence, while TNt only presented a strong temporal structure. Spatio-temporal ordinary kriging (stOK) was applied to predict the spatio-temporal distributions of NH4N, NO3N and TN over the catchment. The cross-validation results indicated that the stOK predictions for NH4N (r=0.48, RMSE=1.11 mg N L-1), NO3N (r=0.46, RMSE=1.21 mg N L-1) outperformed that for TN (r=0.29, RMSE=2.11 mg N L-1). Referenced to the Chinese Environmental Quality Standards for Groundwater (GB/T 14848-93), the proportions of areas contaminated by NH4N, NO3N and TN in the catchment over a 33-month period were 20.5%, 1.46%, and 5.07%, respectively. Our findings suggested that the Jinjing groundwater was mainly polluted by NH4N, which is probably attributed to the intensive rice agriculture featured with high urea fertilizer applications in the catchment.

  11. Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

    NASA Astrophysics Data System (ADS)

    Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

    2014-05-01

    Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the

  12. 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. PMID:23771202

  13. Watershed scale spatial variability in dissolved and total organic and inorganic carbon in contrasting UK catchments

    NASA Astrophysics Data System (ADS)

    Cumberland, S.; Baker, A.; Hudson, N. J.

    2006-12-01

    Approximately 800 organic and inorganic carbon analyses have been undertaken from watershed scale and regional scale spatial surveys in various British catchments. These include (1) a small (<100 sq-km) urban catchment (Ouseburn, N England); (2) a headwater, lowland agricultural catchment (River Tern, C England) (3) a large UK catchment (River Tyne, ~3000 sq-km) and (4) a spatial survey of ~300 analyses from rivers from SW England (~1700 sq-km). Results demonstrate that: (1) the majority of organic and inorganic carbon is in the dissolved (DOC and DIC) fractions; (2) that with the exception of peat rich headwaters, DIC concentration is always greater than DOC; (3) In the rural River Tern, riverine DOC and DIC are shown to follow a simple end- member mixing between DIC (DOC) rich (poor) ground waters and DOC (DIC) rich (poor) riparian wetlands for all sample sites. (4) In the urbanized Ouseburn catchment, although many sample sites also show this same mixing trend, some tributaries follow a pollutant trend of simultaneous increases in both DOC and DIC. The Ouseburn is part of the larger Tyne catchment: this larger catchment follows the simple groundwater DIC- soil water DOC end member mixing model, with the exception of the urban catchments which exhibit an elevated DIC compared to rural sites. (5) Urbanization is demonstrated to increase DIC compared to equivalent rural catchments; this DIC has potential sources including diffuse source inputs from the dissolution of concrete, point sources such as trade effluents and landfill leachates, and bedrock derived carbonates relocated to the soil dissolution zone by urban development. (6) DIC in rural SW England demonstrates that spatial variability in DIC can be attributed to variations in geology; but that DIC concentrations in the SW England rivers dataset are typically lower than the urbanized Tyne catchments despite the presence of carbonate bedrock in many of the sample catchments in the SW England dataset. (7

  14. 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

  15. 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.

  16. Impact of selected agricultural management options on the reduction of nitrogen loads in three representative meso scale catchments in Central Germany.

    PubMed

    Rode, Michael; Thiel, Enrico; Franko, Uwe; Wenk, Gerald; Hesser, Fred

    2009-05-15

    Nitrogen inputs into surface waters from diffuse sources are still unduly high and the assessment of mitigation measures is associated with large uncertainties. The objective of this paper is to investigate selected agricultural management scenarios on nitrogen loads and to assess the impact of differing catchment characteristics in central Germany. A new modelling approach, which simulates spatially distributed N-transport and transformation processes in soil and groundwater, was applied to three meso scale catchments with strongly deviating climate, soil and topography conditions. The approach uses the integrated modelling framework JAMS to link an agro-ecosystem, a rainfall-runoff and a groundwater nitrogen transport model. Different agricultural management measures with deviating levels of acceptance were analysed in the three study catchments. N-leaching rates in all three catchments varied with soil type, the lowest leaching rates being obtained for loess soil catchment (18.5 kg nitrate N ha(-1) yr(-1)) and the highest for the sandy soils catchment (41.2 kg nitrate N ha(-1) yr(-1)). The simulated baseflow nitrogen concentrations varied between the catchments from 1 to 6 mg N l(-1), reflecting the nitrogen reduction capacity of the subsurfaces. The management scenarios showed that the highest N leaching reduction could be achieved by good site-adapted agricultural management options. Nitrogen retention in the subsurface did not alter the ranking of the management scenarios calculated as losses from the soil zone. The reduction effect depended strongly on site specific conditions, especially climate, soil variety and the regional formation of the crop rotations. PMID:19261322

  17. 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

  18. 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

  19. Map-based prediction of organic carbon in headwater streams improved by downstream observations from the river outlet

    NASA Astrophysics Data System (ADS)

    Temnerud, J.; von Brömssen, C.; Fölster, J.; Buffam, I.; Andersson, J.-O.; Nyberg, L.; Bishop, K.

    2016-01-01

    In spite of the great abundance and ecological importance of headwater streams, managers are usually limited by a lack of information about water chemistry in these headwaters. In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the chemistry of upstream headwaters (size < 2 km2), relative to models based on map information alone. We use the concentration of total organic carbon (TOC), an important stream ecosystem parameter, as the target for our study. Between 2000 and 2008, we carried out 17 synoptic surveys in 9 mesoscale catchments (size 32-235 km2). Over 900 water samples were collected in total, primarily from headwater streams but also including each catchment's river outlet during every survey. First we used partial least square regression (PLS) to model the distribution (median, interquartile range (IQR)) of headwater stream TOC for a given catchment, based on a large number of candidate variables including sub-catchment characteristics from GIS, and measured river chemistry at the catchment outlet. The best candidate variables from the PLS models were then used in hierarchical linear mixed models (MM) to model TOC in individual headwater streams. Three predictor variables were consistently selected for the MM calibration sets: (1) proportion of forested wetlands in the sub-catchment (positively correlated with headwater stream TOC), (2) proportion of lake surface cover in the sub-catchment (negatively correlated with headwater stream TOC), and (3) river outlet TOC (positively correlated with headwater stream TOC). Including river outlet TOC improved predictions, with 5-15 % lower prediction errors than when using map information alone. Thus, data on water chemistry measured at river outlets offer information which can complement GIS-based modelling of headwater stream chemistry.

  20. 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

  1. Using 137Cs technique to quantify soil erosion and deposition rates in an agricultural catchment in the black soil region, Northeast China

    NASA Astrophysics Data System (ADS)

    Fang, Haiyan; Sun, Liying; Qi, Deli; Cai, Qiangguo

    2012-10-01

    Soil erosion significantly affects the productive black soil region in Northeast China. Quantification of the soil erosion is necessary for designing efficient degradation control strategies. 137Cs measurements undertaken on 61 sampling points collected within a 28.5 ha agricultural catchment in the black soil region of Northeast China were used to establish the magnitude and spatial pattern of soil redistribution rates as well as sediment budget within the catchment. Estimated soil redistribution rates using the Mass Balance Model 2 (MBM2) ranged from - 56.8 to 171.4 t ha- 1 yr- 1 for the sampling points that were verified by means of both runoff plot data and pedological investigation. Erosion generally occurred behind the shelterbelts, especially in the ephemeral gully susceptible areas, while deposition mainly occurred along the shelterbelts and at the catchment outlet. In the study catchment, 69% of the eroded sediments came from the slopes and 31% the ephemeral gullies. Sediments deposited along the shelterbelts at a rate of ca. 78 t yr- 1 and ca. 33 t yr- 1 at the catchment outlet. The gross soil loss rate for the catchment was - 4.4 t ha- 1 yr- 1 with a sediment delivery ratio of 53%. The mean rate of - 14.5 t ha- 1 yr- 1 in the erosion areas was much higher than the tolerable value, suggesting that effective soil conservation measures are urgently required to reduce the severe black soil loss for sustainable management of the soil resource.

  2. Map-based prediction of organic carbon in headwaters streams improved by downstream observations from the river outlet

    NASA Astrophysics Data System (ADS)

    Temnerud, J.; von Brömssen, C.; Fölster, J.; Buffam, I.; Andersson, J.-O.; Nyberg, L.; Bishop, K.

    2015-06-01

    In spite of the great abundance and ecological importance of headwater streams, managers are usually limited by a lack of information about water chemistry in these headwaters. In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the chemistry of upstream headwaters (size < 2 km2), relative to models based on map information alone. Between 2000 and 2008, we conducted 17 synoptic surveys of streams within 9 mesoscale catchments (size 32-235 km2). Over 900 water samples were collected from catchments ranging in size from 0.03 to 235 km2. First we used partial least square regression (PLS) to model headwater stream total organic carbon (TOC) median and interquartile values for a given catchment, based on a large number of candidate variables including catchment characteristics from GIS, and measured chemistry at the catchment outlet. The best candidate variables from the PLS models were then used in hierarchical linear mixed models (MM) to model TOC in individual headwater streams. Three predictor variables were consistently selected for the MM calibration sets: (1) proportion of forested wetlands in the sub-catchment (positively correlated with headwater stream TOC), (2) proportion of lake surface cover in the sub-catchment (negatively correlated with headwater stream TOC), and (3) whole-catchment river outlet TOC (positively correlated with headwater stream TOC). Including river outlet TOC as a predictor in the models gave 5-15% lower prediction errors than using map information alone. Thus, data on water chemistry measured at river outlets offers information which can complement GIS-based modelling of headwater stream chemistry.

  3. Ammonium release from a blanket peatland into headwater stream systems.

    PubMed

    Daniels, S M; Evans, M G; Agnew, C T; Allott, T E H

    2012-04-01

    Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation. PMID:22285801

  4. Atmospheric NH3 and NO2 concentration and nitrogen deposition in an agricultural catchment of Eastern China.

    PubMed

    Yang, Rong; Hayashi, Kentaro; Zhu, Bin; Li, Feiyue; Yan, Xiaoyuan

    2010-09-15

    To assess the atmospheric environmental impacts of anthropogenic reactive nitrogen in the fast-developing Eastern China region, we measured atmospheric concentrations of nitrogen dioxide (NO(2)) and ammonia (NH(3)) as well as the wet deposition of inorganic nitrogen (NO(3)(-) and NH(4)(+)) and dissolved organic nitrogen (DON) levels in a typical agricultural catchment in Jiangsu Province, China, from October 2007 to September 2008(.) The annual average gaseous concentrations of NO(2) and NH(3) were 42.2 microg m(-3) and 4.5 microg m(-3) (0 degree C, 760 mm Hg), respectively, whereas those of NO(3)(-), NH(4)(+), and DON in the rainwater within the study catchment were 1.3, 1.3, and 0.5 mg N L(-1), respectively. No clear difference in gaseous NO(2) concentrations and nitrogen concentrations in collected rainwater was found between the crop field and residential sites, but the average NH(3) concentration of 5.4 microg m(-3) in residential sites was significantly higher than that in field sites (4.1 microg m(-3)). Total depositions were 40 kg N ha(-1) yr(-1) for crop field sites and 30 kg N ha(-1) yr(-1) for residential sites, in which dry depositions (NO(2) and NH(3)) were 7.6 kg N ha(-1) yr(-1) for crop field sites and 1.9 kg N ha(-1) yr(-1) for residential sites. The DON in the rainwater accounted for 16% of the total wet nitrogen deposition. Oxidized N (NO(3)(-) in the precipitation and gaseous NO(2)) was the dominant form of nitrogen deposition in the studied region, indicating that reactive forms of nitrogen created from urban areas contribute greatly to N deposition in the rural area evaluated in this study. PMID:20624633

  5. HYDROGEOLOGIC CONTROLS ON NITRATE TRANSPORT IN A SMALL AGRICULTURAL CATCHMENT, IOWA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of subsurface lithology 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 ...

  6. 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...

  7. Lacustrine wetland in an agricultural catchment: nitrogen removal and related biogeochemical processes

    NASA Astrophysics Data System (ADS)

    Balestrini, R.; Arese, C.; Delconte, C.

    2007-09-01

    The role of specific catchment areas, such as the soil-river or lake interfaces, in removing or buffering the flux of N from terrestrial to aquatic ecosystems is globally recognized but the extreme variability of microbiological and hydrological processes make it difficult to predict the extent to which different wetlands function as buffer systems. In this paper we evaluate the degree to which biogeochemical processes in a lacustrine wetland are responsible for the nitrate removal from ground waters feeding Candia Lake (Northern Italy). A transect of 18 piezometers was installed perpendicular to the shoreline, in a sub-unit formed by 80 m of poplar plantation, close to a crop field and 30 m of reed swamp. The chemical analysis revealed a drastic NO3-N ground water depletion from the crop field to the lake, with concentrations decreasing from 15-18 mg N/l to the detection limit within the reeds. Patterns of Cl, SO4, O2, NO2-N, HCO3 and DOC suggest that the metabolic activity of bacterial communities, based on the differential use of electron donors and acceptors in redox reactions is the key function of this system. The significant inverse relationship found between NO3-N and HCO3 is a valuable indicator of the denitrification activity. The pluviometric regime, the temperature, the organic carbon availability and the hydrogeomorphic properties are the main environmental factors affecting the N transformations in the studied lacustrine ecosystem.

  8. Lacustrine wetland in an agricultural catchment: nitrogen removal and related biogeochemical processes

    NASA Astrophysics Data System (ADS)

    Balestrini, R.; Arese, C.; Delconte, C.

    2008-03-01

    The role of specific catchment areas, such as the soil-river or lake interfaces, in removing or buffering the flux of N from terrestrial to aquatic ecosystems is globally recognized but the extreme variability of microbiological and hydrological processes make it difficult to predict the extent to which different wetlands function as buffer systems. In this paper we evaluate the degree to which biogeochemical processes in a lacustrine wetland are responsible for the nitrate removal from ground waters feeding Candia Lake (Northern Italy). A transect of 18 piezometers was installed perpendicular to the shoreline, in a sub-unit formed by 80 m of poplar plantation, close to a crop field and 30 m of reed swamp. The chemical analysis revealed a drastic NO3--N ground water depletion from the crop field to the lake, with concentrations decreasing from 15-18 mg N/l to the detection limit within the reeds. Patterns of Cl-, SO42-, O2, NO2--N, HCO3- and DOC suggest that the metabolic activity of bacterial communities, based on the differential use of electron donors and acceptors in redox reactions is the key function of this system. The significant inverse relationship found between NO3--N and HCO3- is a valuable indicator of the denitrification activity. The pluviometric regime, the temperature, the organic carbon availability and the hydrogeomorphic properties are the main environmental factors affecting the N transformations in the studied lacustrine ecosystem.

  9. 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. PMID:26645075

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Sulphate leaching from diffuse agricultural and forest sources in a large central European catchment during 1900-2010.

    PubMed

    Kopáček, Jiří; Hejzlar, Josef; Porcal, Petr; Posch, Maximilian

    2014-02-01

    Using dynamic, mass budget, and empirical models, we quantified sulphate-sulphur (SO4-S) leaching from soils in a large central European catchment (upper Vltava river, Czech Republic) over a 110-year period (1900-2010). SO4-S inputs to soils with synthetic fertilisers and atmospheric deposition increased in the 1950s-1980s, then rapidly decreased (~80%), and remained low since the middle 1990s. The proportion of drained agricultural land rapidly increased from 4 to 43% between the 1950s and 1990s; then the draining ability of the system slowly decreased due to its ageing. Sulphate concentrations in the Vltava exhibited similar trends as the external SO4-S inputs, suggesting that they could be explained by changes in atmospheric and fertiliser S inputs. The available data and modelling, however, showed that (i) internal SO4-S sources (mineralization of soil organic S in the drained agricultural land), (ii) a hysteresis in SO4-S leaching from forest soils (a net S retention at the high S inputs and then a net release at the lowered inputs), and (iii) hydrology must be taken into account. An empirical model was then employed, based on parameters representing hydrology (discharge), external SO4-S sources (inputs by synthetic fertilisers and atmospheric deposition), and internal SO4-S sources (mineralization related to soil drainage). The model explained 84% of the observed variability in annual SO4-S concentrations in the Vltava river during 1900-2010 and showed that forest soils were a net sink (105 kg ha(-1)) while agricultural land was a net source (55 kg ha(-1)) of SO4-S during 1960-2010. In the late 1980s, forest soils changed from a sink to a source of S, and the present release of SO4-S accumulated in forest soils thus delays recovery of surface waters from acidification, while S losses from agricultural soils increase the risk of future S deficiency in S-demanding crops. PMID:24176702

  15. 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.

  16. Evaluating the critical source area concept of phosphorus loss from soils to water-bodies in agricultural catchments.

    PubMed

    Shore, M; Jordan, P; Mellander, P-E; Kelly-Quinn, M; Wall, D P; Murphy, P N C; Melland, A R

    2014-08-15

    Using data collected from six basins located across two hydrologically contrasting agricultural catchments, this study investigated whether transport metrics alone provide better estimates of storm phosphorus (P) loss from basins than critical source area (CSA) metrics which combine source factors as well. Concentrations and loads of P in quickflow (QF) were measured at basin outlets during four storm events and were compared with dynamic (QF magnitude) and static (extent of highly-connected, poorly-drained soils) transport metrics and a CSA metric (extent of highly-connected, poorly-drained soils with excess plant-available P). Pairwise comparisons between basins with similar CSA risks but contrasting QF magnitudes showed that QF flow-weighted mean TRP (total molybdate-reactive P) concentrations and loads were frequently (at least 11 of 14 comparisons) more than 40% higher in basins with the highest QF magnitudes. Furthermore, static transport metrics reliably discerned relative QF magnitudes between these basins. However, particulate P (PP) concentrations were often (6 of 14 comparisons) higher in basins with the lowest QF magnitudes, most likely due to soil-management activities (e.g. ploughing), in these predominantly arable basins at these times. Pairwise comparisons between basins with contrasting CSA risks and similar QF magnitudes showed that TRP and PP concentrations and loads did not reflect trends in CSA risk or QF magnitude. Static transport metrics did not discern relative QF magnitudes between these basins. In basins with contrasting transport risks, storm TRP concentrations and loads were well differentiated by dynamic or static transport metrics alone, regardless of differences in soil P. In basins with similar transport risks, dynamic transport metrics and P source information additional to soil P may be required to predict relative storm TRP concentrations and loads. Regardless of differences in transport risk, information on land use and

  17. 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

  18. 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

  19. 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.

  20. A classification of drainage and macropore flow in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Heppell, C. M.; Worrall, F.; Burt, T. P.; Williams, R. J.

    2002-01-01

    This paper uses a variety of multivariate statistical techniques in order to improve current understanding of the antecedent and rainfall controls on drainage characteristics for an agricultural underdrained clay site. Using the dataset obtained from a two-year hillslope study at Wytham (Oxfordshire, UK) a number of patterns in the nature and style of drainage events were explored. First, using principal components analysis, a distinction was drawn between drainflow controlled by antecedent conditions and drainflow controlled by rainfall characteristics. Dimensional analysis then distinguished between two further types of drainflow event: antecedent limited events (ALE) and non-antecedent limited events (NALE). These were drainflow events requiring a minimum antecedent hydraulic head to occur (ALE) and events that occurred in response to rainfall irrespective of the antecedent conditions, because the rainfall was either of high enough intensity or duration to prompt a response in drainflow (NALE). 2. The dataset also made possible a preliminary investigation into the controls on and types of macropore flow at the site. Principal components analysis identified that rainfall characteristics were more important than antecedent conditions in generating high proportions of macropore flow in drainflow. Of the rainfall characteristics studied, rainfall amount and intensity were the dominant controls on the amount of macropore flow, with duration as a secondary control. Two styles of macropore flow were identified: intensity-driven and duration-driven. Intensity-driven events are characterized by rainfall of high intensity and short duration. During such events the amount of macropore flow is proportional to the rainfall intensity and the interaction between macropore and matrix flow is kinetically limited. The second style of macropore flow is characterized by long-duration events. For these events the amount of macropore flow approaches a maximum value whatever the

  1. 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

  2. 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. PMID:24534695

  3. 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

  4. Spatial and temporal changes in apportionments by using sediment fingerprinting in a Spanish Pyrenean river catchment.

    NASA Astrophysics Data System (ADS)

    Palazón, Leticia; Latorre, Borja; Gaspar, Leticia; Navas, Ana

    2016-04-01

    The Barasona reservoir has suffered from siltation since its construction, with the loss of over one third of its storage volume in around 30 years (period 1972-1996). Information on sediment contribution and transport dynamics from the contributing catchment to the reservoir is needed to develop management plans for maintaining reservoir sustainability. Large variability in sediment delivery was found in previous studies in the Barasona catchment (1509 km2, Central Spanish Pyrenees) and the major sediment sources identified included badlands developed in the middle part of the catchment and the agricultural fields in its lower part. In this study the < 63 μm sediment fraction from the channel bed sediment samples from the main rivers (Ésera and Isábena), their tributaries and surface reservoir sediments, the latter spanning two decades, are investigated following the fingerprinting procedure to assess how the land use sediment contributions change along the streams and on time to the reservoir. Subsoil source (badlands included) contributions to channel bed sediments of the main rivers are limited in the catchment headwater which turn to be greater than 70 % for river reaches closer to the reservoir. In the same way, the presence of the badlands and the greater percentage of bare soils in the southern part of the catchment are main source of sediments (> 50%) for the southern tributaries. Differences in source apportionments between the two time-spanning reservoir samples reveal that agricultural fields contributed more in the 90s. Study fine sediment characteristics and their contributions in river catchments provide unique and diverse information to address catchment management problems, improving the spatial and temporal knowledge of land use sediment source contributions along the catchment to the reservoir infill.

  5. 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

  6. Modelling the impact of prescribed global warming on runoff from headwater catchments of the Irrawaddy River and their implications for the water level regime of Loktak Lake, northeast India

    NASA Astrophysics Data System (ADS)

    Singh, C. R.; Thompson, J. R.; French, J. R.; Kingston, D. G.; Mackay, A. W.

    2010-09-01

    Climate change is likely to have major implications for wetland ecosystems, which will include altered water level regimes due to modifications in local and catchment hydrology. However, substantial uncertainty exists in the precise impacts of climate change on wetlands due in part to uncertainty in GCM projections. This paper explores the impacts of climate change upon river discharge within three sub-catchments of Loktak Lake, an internationally important wetland in northeast India. This is achieved by running pattern-scaled GCM output through distributed hydrological models (developed using MIKE SHE) of each sub-catchment. The impacts of climate change upon water levels within Loktak Lake are subsequently investigated using a water balance model. Two groups of climate change scenarios are investigated. Group 1 uses results from seven different GCMs for an increase in global mean temperature of 2 °C, the purported threshold of ''dangerous'' climate change, whilst Group 2 is based on results from the HadCM3 GCM for increases in global mean temperature between 1 °C and 6 °C. Results from the Group 1 scenarios show varying responses between the three sub-catchments. The majority of scenario-sub-catchment combinations (13 out of 21) indicate increases in discharge which vary from <1% to 42% although, in some cases, discharge decreases by as much as 20%. Six of the GCMs suggest overall increases in river flow to Loktak Lake (2-27%) whilst the other results in a modest (6%) decline. In contrast, the Group 2 scenarios lead to an almost linear increase in total river flow to Loktak Lake with increasing temperature (up to 27% for 6 °C), although two sub-catchments experience reductions in mean discharge for the smallest temperature increases. In all but one Group 1 scenario, and all the Group 2 scenarios, Loktak Lake water levels are higher, regularly reaching the top of a downstream hydropower barrage that impounds the lake and necessitating the release of water for

  7. Prediction of dissolved reactive phosphorus losses from small agricultural catchments: calibration and validation of a parsimonious model

    NASA Astrophysics Data System (ADS)

    Hahn, C.; Prasuhn, V.; Stamm, C.; Lazzarotto, P.; Evangelou, M. W. H.; Schulin, R.

    2013-01-01

    Eutrophication of surface waters due to diffuse phosphorus (P) losses continues to be a severe water quality problem world-wide, causing the loss of ecosystem functions of the respective water bodies. Phosphorus in runoff often originates from a small fraction of a catchment only. Targeting mitigation measures to these critical source areas (CSA) is expected to be most efficient and cost-effective, but requires suitable tools. Here we investigated the capability of the parsimonious Rainfall-Runoff-Phosphorus (RRP) model to identify CSA in grassland-dominated catchments based on readily available soil and topographic data. After simultaneous calibration on runoff data from four small hilly catchments on the Swiss Plateau, the model was validated on a different catchment in the same region without further calibration. The RRP model adequately simulated the discharge and dissolved reactive P (DRP) export from the validation catchment. Sensitivity analysis showed that the model predictions were robust with respect to the classification of soils into "poorly drained" and "well drained", based on the available soil map. Comparing spatial hydrological model predictions with field data from the validation catchment provided further evidence that the assumptions underlying the model are valid and that the model adequately accounts for the dominant P export processes in the target region. Thus, the parsimonious RRP model is a valuable tool that can be used to determine CSA. Despite the considerable predictive uncertainty regarding the spatial extent of CSAs the RRP can provide guidance for the implementation of mitigation measures. The model helps to identify those parts of a catchment where high DRP losses are expected or can be excluded with high confidence. Legacy P was predicted to be the dominant source for DRP losses and thus, in combination with hydrologic active areas, a high risk for water quality.

  8. Prediction of dissolved reactive phosphorus losses from small agricultural catchments: calibration and validation of a parsimonious model

    NASA Astrophysics Data System (ADS)

    Hahn, C.; Prasuhn, V.; Stamm, C.; Lazzarotto, P.; Evangelou, M. W. H.; Schulin, R.

    2013-10-01

    Eutrophication of surface waters due to diffuse phosphorus (P) losses continues to be a severe water quality problem worldwide, causing the loss of ecosystem functions of the respective water bodies. Phosphorus in runoff often originates from a small fraction of a catchment only. Targeting mitigation measures to these critical source areas (CSAs) is expected to be most efficient and cost-effective, but requires suitable tools. Here we investigated the capability of the parsimonious Rainfall-Runoff-Phosphorus (RRP) model to identify CSAs in grassland-dominated catchments based on readily available soil and topographic data. After simultaneous calibration on runoff data from four small hilly catchments on the Swiss Plateau, the model was validated on a different catchment in the same region without further calibration. The RRP model adequately simulated the discharge and dissolved reactive P (DRP) export from the validation catchment. Sensitivity analysis showed that the model predictions were robust with respect to the classification of soils into "poorly drained" and "well drained", based on the available soil map. Comparing spatial hydrological model predictions with field data from the validation catchment provided further evidence that the assumptions underlying the model are valid and that the model adequately accounts for the dominant P export processes in the target region. Thus, the parsimonious RRP model is a valuable tool that can be used to determine CSAs. Despite the considerable predictive uncertainty regarding the spatial extent of CSAs, the RRP can provide guidance for the implementation of mitigation measures. The model helps to identify those parts of a catchment where high DRP losses are expected or can be excluded with high confidence. Legacy P was predicted to be the dominant source for DRP losses and thus, in combination with hydrologic active areas, a high risk for water quality.

  9. Developing restoration strategies for channelized headwater streams within a central Ohio watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channelized headwater streams are a common landscape feature in the midwestern United States. These streams have been channelized and maintained for removal of excess water from agricultural fields without regard for the aquatic biota. Development of restoration strategies for channelized headwater ...

  10. Influence of Riparian Habitat and Nutrients on Aquatic Communities Within Riparian Zones of Headwater Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Headwater streams are the smallest streams in a watershed. Their small size and high frequency of occurrence make them susceptible to anthropogenic habitat alterations. Many headwater streams in the Midwestern United States have been channelized to drain agricultural fields. Aquatic macroinvertebrat...

  11. Hydroclimatic Controls on the Seasonal and Inter-Annual Variability of Dissolved Phosphorus Concentration in a Lowland Agricultural Catchment

    NASA Astrophysics Data System (ADS)

    Dupas, R.; Gascuel-odoux, C.; Grimaldi, C.; Gruau, G.

    2014-12-01

    We investigated soluble reactive phosphorus (SRP) at the outlet of a lowland agricultural catchment (Kervidy-Naizin, France) to identify the hydroclimatic controls on the seasonal and inter-annual variability in concentrations. Six years of stream data have been used, including a regular 6-daily sampling and high-frequency monitoring of 52 floods. Both on an annual basis and during flood events, distinct export dynamics for SRP and particulate phosphorus (PP) revealed that SRP transport mechanism was independent from PP (Dupas et al., submitted). During most flood events, discharge-SRP hystereses were anticlockwise, which suggests that SRP was transferred to the stream via subsurface flow. Groundwater rise in wetland soils was likely the cause of this transfer, through the hydrological connectivity it created between the stream and P-rich soil horizons. SRP concentrations were highest in the beginning of the hydrological year (period A), when the stream started to flow again after the dry summer season and water table fluctuated in the wetland domain. Thus, wetland soils seemed to be a major source of SRP. Concentrations during period A were higher after a long summer period than after a short one, which suggest that a pool of labile P was constituted in soils during the dry summer period. During winter (period B), SRP concentration generally decreased compared to period A, both during floods and interflood. This could be due to depletion of a soil P pool in the wetland domain and/or dilution by deep groundwater with low P concentration from the upland domain. Concentration during period B barely decreased compared to A during wet years, probably due to increased connectivity with soils from the upland domain in wet conditions. During spring (period C), SRP concentration increased during baseflow periods. The possible mechanisms causing the release of SRP could involve reduction of Fe oxide-hydroxides in wetland soils or in-stream processes. At the same time, SRP

  12. 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.

  13. 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

    2012-08-01

    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. PMID:22789002

  14. 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

  15. 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

  16. 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

  17. Assessing the Impact of Agricultural Pressures on N and P Loads and Potential Eutrophication Risk at Regional Scales

    NASA Astrophysics Data System (ADS)

    Dupas, R.; Gascuel-odoux, C.; Delmas, M.; Moatar, F.

    2014-12-01

    Excessive nutrient loading of freshwater bodies results in increased eutrophication risk worldwide. The processes controlling N/P transfer in agricultural landscapes are well documented through scientific studies conducted in intensively monitored catchments. However, managers need tools to assess water quality and evaluate the contribution of agriculture to eutrophication at regional scales, including unmonitored or poorly monitored areas. To this end, we present an assessment framework which includes: i) a mass-balance model to estimate diffuse N/P transfer and retention and ii) indicators based on N:P:Si molar ratios to assess potential eutrophication risk from external loads. The model, called Nutting (Dupas et al., 2013), integrates variables for both detailed description of agricultural pressures (N surplus, soil P content) and characterisation of physical attributes of catchments (including spatial attributes). It was calibrated on 160 catchments, and applied to 2210 unmonitored headwater bodies in France (Dupas et al., under review). N and P retention represented 53% and 95% of soil N and P surplus, respectively, and was mainly controlled by runoff and an index characterising infiltration/runoff properties. According to our estimates, diffuse agricultural sources represented a mean of 97% of N loads and N exceeded Si in 93% of the catchments, whilst they represented 46% of P loads and P exceeded Si in 26-65% of the catchments. Estimated eutrophication risk was highly sensitive to assumptions about P bioavailability, hence the range of headwaters potentially at risk spanned 26-63% of the catchments, depending on assumptions. To reduce this uncertainty, we recommend introducing P bioavailability tests in water monitoring programs, especially in sensitive areas. Dupas R et al. Assessing N emissions in surface water at the national level: comparison of country-wide vs. regionalized models. Sci Total Environ 2013; 443: 152-62. Dupas R et al. Assessing the impact

  18. 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

  19. 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...

  20. Impact of land use, soil and DEM databases on surface runoff assessment with GIS decision support tool: A study case on the Briançon vineyard catchment (Gard, France)

    NASA Astrophysics Data System (ADS)

    Regazzoni, C.; Payraudeau, S.

    2012-04-01

    Runoff and associated erosion represent a primary mode of mobilization and transfer of pesticides from agricultural lands to watercourses and groundwater. The pesticides toxicity is potentially higher at the headwater catchment scale. These catchments are usually ungauged and characterized by temporary streams. Several mitigation strategies and management practices are currently used to mitigate the pesticides mixtures in agro-ecosystems. Among those practices, Stormwater Wetlands (SW) could be implemented to store surface runoff and to mitigate pesticides loads. The implementation of New Potential Stormwater Wetlands (NPSW) requires a diagnosis of intermittent runoff at the headwater catchment scale. The main difficulty to perform this diagnosis at the headwater catchment scale is to spatially characterize with enough accuracy the landscape components. Indeed, fields and field margins enhance or decrease the runoff and determine the pathways of hortonian overland flow. Land use, soil and Digital Elevation Model databases are systematically used. The question of the respective weight of each of these databases on the uncertainty of the diagnostic results is rarely analyzed at the headwater catchment scale. Therefore, this work focused (i) on the uncertainties of each of these databases and their propagation on the hortonian overland flow modelling, (ii) the methods to improve the accuracy of each database, (iii) the propagation of the databases uncertainties on intermittent runoff modelling and (iv) the impact of modelling cell size on the diagnosis. The model developed was a raster approach of the SCS-CN method integrating re-infiltration processes. The uncertainty propagation was analyzed on the Briançon vineyard catchment (Gard, France, 1400 ha). Based on this study site, the results showed that the geographic and thematic accuracies of regional soil database (1:250 000) were insufficient to correctly simulate the hortonian overland flow. These results have to

  1. 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

  2. Relationships of macroinvertebrate communities with nutrients, pesticides, and physicochemical parameters in channelized headwater streams in Indiana and Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many headwater streams in the midwestern United States have been modified or constructed to transport agricultural runoff downstream. Effective implementation of agricultural conservation practices to reduce nutrient and pesticide loadings requires information about the influence of water chemistry ...

  3. 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

  4. 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

  5. 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

  6. Daily nitrate losses: implication on long-term river quality in an intensive agricultural catchment of southwestern france.

    PubMed

    Boithias, Laurie; Srinivasan, Raghavan; Sauvage, Sabine; Macary, Francis; Sánchez-Pérez, José Miguel

    2014-01-01

    High nitrate concentrations in streams have become a widespread problem throughout Europe in recent decades, damaging surface water and groundwater quality. The European Nitrate Directive fixed a potability threshold of 50 mg L for European rivers. The performance of the Soil and Water Assessment Tool model was assessed in the 1110-km Save catchment in southwestern France for predicting water discharge and nitrate loads and concentrations at the catchment outlet, considering observed data set uncertainty. Simulated values were compared with intensive and extensive measurement data sets. Daily discharge fitted observations (Nash-Sutcliffe efficiency coefficient = 0.61, = 0.7, and PBIAS = -22%). Nitrate simulation (1998-2010) was within the observed range (PBIAS = 10-21%, considering observed data set uncertainty). Annual nitrate load at the catchment outlet was correlated to the annual water yield at the outlet ( = 0.63). Simulated annual catchment nitrate exportation ranged from 21 to 49 kg ha depending on annual hydrological conditions (average, 36 kg ha). Exportation rates ranged from 3 to 8% of nitrogen inputs. During floods, 34% of the nitrate load was exported, which represented 18% of the 1998-2010 period. Average daily nitrate concentration at the outlet was 29 mg L (1998-2010), ranging from 0 to 270 mg L. Nitrate concentration exceeded the European 50 mg L potability threshold during 244 d between 1998 and 2010. A 20% reduction of nitrogen input reduced crop yield by between 5 and 9% and reduced by 62% the days when the 50 mg L threshold was exceeded. PMID:25602539

  7. 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

  8. Headwaters are critical reservoirs of microbial diversity for fluvial networks

    PubMed Central

    Besemer, Katharina; Singer, Gabriel; Quince, Christopher; Bertuzzo, Enrico; Sloan, William; Battin, Tom J.

    2013-01-01

    Streams and rivers form conspicuous networks on the Earth and are among nature's most effective integrators. Their dendritic structure reaches into the terrestrial landscape and accumulates water and sediment en route from abundant headwater streams to a single river mouth. The prevailing view over the last decades has been that biological diversity also accumulates downstream. Here, we show that this pattern does not hold for fluvial biofilms, which are the dominant mode of microbial life in streams and rivers and which fulfil critical ecosystem functions therein. Using 454 pyrosequencing on benthic biofilms from 114 streams, we found that microbial diversity decreased from headwaters downstream and especially at confluences. We suggest that the local environment and biotic interactions may modify the influence of metacommunity connectivity on local biofilm biodiversity throughout the network. In addition, there was a high degree of variability in species composition among headwater streams that could not be explained by geographical distance between catchments. This suggests that the dendritic nature of fluvial networks constrains the distributional patterns of microbial diversity similar to that of animals. Our observations highlight the contributions that headwaters make in the maintenance of microbial biodiversity in fluvial networks. PMID:24089333

  9. PSYCHIC A process-based model of phosphorus and sediment transfers within agricultural catchments. Part 2. A preliminary evaluation

    NASA Astrophysics Data System (ADS)

    Strömqvist, J.; Collins, A. L.; Davison, P. S.; Lord, E. I.

    2008-02-01

    SummaryThis paper describes the preliminary evaluation of the PSYCHIC catchment scale (Tier 1) model for predicting the mobilisation and delivery of phosphorus (P) and suspended sediment (SS) in the Hampshire Avon (1715 km 2) and Herefordshire Wye (4017 km 2) drainage basins, in the UK, using empirical data. Phosphorus and SS transfers to watercourses in the Wye were predicted to be greater than corresponding delivery in the Avon; SS, 249 vs 33 kg ha -1 yr -1; DP, 2.57 vs 1.26 kg ha -1 yr -1; PP, 2.20 vs 0.56 kg ha -1 yr -1. The spatial pattern of the predicted transfers was relatively uniform across the Wye drainage basin, whilst in the Avon, delivery to watercourses was largely confined to the river corridors and small areas of drained land. Statistical performance in relation to predicted exports of P and SS, using criteria for relative error (RE) and root mean square error (RMSE), reflected the potential shortcomings associated with using longer-term climate data for predicting shorter-term (2002-2004) catchment response and the need to refine calculations of point source contributions and to incorporate additional river basin processes such as channel bank erosion and in-stream geochemical processing. PSYCHIC is therefore best suited to characterising longer-term catchment response.

  10. 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

  11. 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

  12. 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.

  13. Process type identification in torrential catchments

    NASA Astrophysics Data System (ADS)

    Heiser, Micha; Scheidl, Christian; Eisl, Julia; Spangl, Bernhard; Hübl, Johannes

    2015-04-01

    The classification of torrential processes takes place according to factors like sediment concentration and flow behavior and ranges from fluvial process types, including water floods and fluvial sediment transport processes, to fluvial mass movements such as debris flows. This study hypothises a context between basic geomorphological disposition parameters and potential dominant flow process types in steep headwater catchments. Thus, examined catchments were selected based on a historical event documentation of torrential events in the Austrian Alps. In total, 84 catchments could be analysed, and 11 different morphometric parameters were considered. To predict the dominant torrential process type within a catchment, a naive Bayes classifier, a decision tree model, and a multinomial regression model was trained against the compiled geomorphological disposition parameters. All models as well as their combination were compared, based on bootstrapping and complexity. The presented classification model with the lowest prediction error for our data might help to identify the most likely torrential process within a considered catchment.

  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. 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

  16. 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. PMID:16253306

  17. 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

  18. 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

  19. 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.

  20. Dynamics of nitrate and chloride during storm events in agricultural catchments with different subsurface drainage intensity (Indiana, USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grids of perforated pipe buried beneath many poorly drained agricultural fields in the Midwestern U.S. are believed to “short circuit” pools of nitrate-laden soil water and shallow groundwater directly into streams that eventually discharge to the Mississippi River. Although much is known about the ...

  1. 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...

  2. 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...

  3. 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

  4. Indirect emissions and isotopologue signatures of N2O from agricultural drainage water of a Pleistocene lowland catchment in North-Eastern Germany

    NASA Astrophysics Data System (ADS)

    Weymann, D.; Well, R.; Kahle, P.; Tiemeyer, B.; Flessa, H.

    2011-12-01

    Artificial drainage of low- and wetlands is a common practice in many agricultural regions to facilitate crop production. Agricultural drainage water was shown to be supersaturated with nitrous oxide (N2O), a major greenhouse gas thought to contribute to global warming and to the destruction of stratospheric ozone. Therefore, drainage of agricultural land has potential for indirect N2O emissions which are a highly uncertain component of the global N2O budget. This case study focuses on these emissions and further tries to unravel the source processes of N2O as well as the impact of its hydrological controls by applying an isotopologue approach. The research area was an intensively tile drained agricultural catchment embedded in the Pleistocene lowland of the federal state Mecklenburg-Vorpommern (North-Eastern Germany). Water sampling was conducted during the consecutive hydrological winter periods 2007/2008 and 2008/2009 by sampling a collector drain outlet and an adjacent drainage ditch. Besides concentrations of dissolved N2O and NO3- we determined the isotopologue signatures of N2O by measuring δ15Nbulk and δ18O as well as the 15N 'site preference', which characterizes the intramolecular distribution of the N isotopes within the asymmetric N2O molecule and is a promising tool to distinguish between the main source processes of N2O, nitrification and denitrification. The investigated hydrological winter periods varied considerably concerning the weather and hydrological conditions. During the comparatively wet winter period 2007/2008, indirect N2O emissions accounted for 0.17 kg N2O-N ha-1 a-1 and were thus higher than during the colder and comparatively dry 2008/2009 period, where we found 0.12 kg N2O-N ha-1 a-1. The emission factors for both sampling periods were 0.23 % and 0.17 % of the N input, respectively, and therefore in good agreement with the current IPCC default value of 0.25 %. The isotopologue signatures of N2O reflected the different hydrological

  5. 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. PMID

  6. Modelling long-term diffuse nitrate pollution at the catchment-scale: Data, parameter and epistemic uncertainty

    NASA Astrophysics Data System (ADS)

    Howden, N. J. K.; Burt, T. P.; Mathias, S. A.; Worrall, F.; Whelan, M. J.

    2011-06-01

    SummaryA model of catchment-scale nitrate transport is presented for a small, rural headwater basin (Alton Pancras: <10 km 2) in Dorset, UK, for the period 1930-2007. Estimates of annual nitrogen (N) loading were based on parish land-use data, held in the UK's National Archives, and previously reported figures of typical UK N loadings from livestock, fertiliser, ploughing of permanent pasture, atmospheric deposition, biological fixation and crop uptake. Loading calculations were performed within an uncertainty framework to allow for the reliance on literature data sources. Loading calculations show that all significant sources must be included not just fertiliser application which, at most, contributes 50% of N input in any given year. A simple algorithm was used to transform estimated catchment N loading (1930-2007) into a river nitrate response (observed data: 1980-2004). This assumed N-loads were delayed by some catchment mean travel time (MTT), t a, attenuated according to a Peclet number, P e, converted into solute concentrations by a factor, α, to increase some initial baseline river concentration, C b. Simple graphical translation of estimated catchment N loading to the river concentration data suggested a MTT of around 37 years. As P e → ∞, the transport model simplified to a linear relationship between catchment N load and river nitrate concentration response lagged by the MTT. Hence, the model results suggest that, in this catchment, advection is the dominant mechanism for transport of diffuse pollution from land to river: there is little or no dispersion present. The MTT ( t a) was then reconsidered using an estimated distribution of unsaturated zone depths in the Alton Pancras catchment. Conclusions suggest that, in modelling of long-term nutrient transport, a detailed source term is of much greater importance than a complex hydrogeological model. Implications of epistemic uncertainty, long-term prediction and management of diffuse agricultural

  7. 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

  8. Environmental risk assessment of fluctuating diazinon concentrations in an urban and agricultural catchment using toxicokinetic-toxicodynamic modeling.

    PubMed

    Ashauer, Roman; Wittmer, Irene; Stamm, Christian; Escher, Beate I

    2011-11-15

    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

  9. Baseflow and stormflow metal fluxes from two small agricultural catchments in the Coastal Plain of the Chesapeake Bay Basin, United States

    USGS Publications Warehouse

    Miller, C.V.; Foster, G.D.; Majedi, B.F.

    2003-01-01

    Annual yields (fluxes per unit area) of Al, Mn, Fe, Ni, Cd, Pb, Zn, Cu, Cr, Co, As and Se were estimated for two small non-tidal stream catchments on the Eastern Shore of the Chesapeake Bay, United States - a poorly drained dissected-upland watershed in the Nanticoke River Basin, and a well-drained feeder tributary in the lower reaches of the Chester River Basin. Both watersheds are dominated by agriculture. A hydrograph-separation technique was used to determine the baseflow and stormflow components of metal yields, thus providing important insights into the effects of hydrology and climate on the transport of metals. Concentrations of suspended-sediment were used as a less-costly proxy of metal concentrations which are generally associated with particles. Results were compared to other studies in Chesapeake Bay and to general trends in metal concentrations across the United States. The study documented a larger than background yield of Zn and Co from the upper Nanticoke River Basin and possibly enriched concentrations of As, Cd and Se from both the upper Nanticoke River and the Chesterville Branch (a tributary of the lower Chester River). The annual yield of total Zn from the Nanticoke River Basin in 1998 was 18,000 g/km2/a, and was two to three times higher than yields reported from comparable river basins in the region. Concentrations of Cd also were high in both basins when compared to crustal concentrations and to other national data, but were within reasonable agreement with other Chesapeake Bay studies. Thus, Cd may be enriched locally either in natural materials or from agriculture.

  10. Relationships between water chemistry and fish communities within channelized headwater streams in Indiana and Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many headwater streams in the midwestern United States were channelized for draining agricultural fields. Agricultural conservation practices are implemented to reduce nutrient and pesticide loadings within these altered streams. The impact of these practices is uncertain because the influence of wa...

  11. Catchment controls on solute export

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Schmidt, Christian; Selle, Benny; Fleckenstein, Jan H.

    2015-12-01

    Dynamics of solute export from catchments can be classified in terms of chemostatic and chemodynamic export regimes by an analysis of concentration-discharge relationships. Previous studies hypothesized that distinct export regimes emerge from the presence of solute mass stores within the catchment and their connectivity to the stream. However, so far a direct link of solute export to identifiable catchment characteristics is missing. Here we investigate long-term time series of stream water quality and quantity of nine neighboring catchments in Central Germany ranging from relatively pristine mountain catchments to agriculturally dominated lowland catchments, spanning large gradients in land use, geology, and climatic conditions. Given the strong collinearity of catchment characteristics we used partial least square regression analysis to quantify the predictive power of these characteristics for median concentrations and the metrics of export regime. We can show that median concentrations and metrics of the export regimes of major ions and nutrients can indeed be inferred from catchment characteristics. Strongest predictors for median concentrations were the share of arable land, discharge per area, runoff coefficient and available water capacity in the root zone of the catchments. The available water capacity in the root zone, the share of arable land being artificially drained and the topographic gradient were found to be the most relevant predictors for the metrics of export regime. These catchment characteristics can represent the size of solute mass store such as the fraction of arable land being a measure for the store of nitrate. On the other hand, catchment characteristics can be a measure for the connectivity of these solute stores to the stream such as the fraction of tile drained land in the catchments. This study demonstrates the potential of data-driven, top down analyses using simple metrics to classify and better understand dominant controls of

  12. Connectivity influences on nutrient and sediment migration in the Wartburg catchment, KwaZulu-Natal Province, South Africa

    NASA Astrophysics Data System (ADS)

    Kollongei, Kipkemboi J.; Lorentz, Simon A.

    Non-point-source (NPS) pollution of surface and groundwater by sediment and nutrient loads emanating from agricultural catchments is a prominent environmental issue, with major consequences on water supply and aquatic ecosystem quality. The concept of connectivity has proved invaluable in understanding migration of NPS pollutants in catchments. Observations of sediments or suspended solids (SS), nitrate (NO3) and phosphorous (P) fluxes alongside stable water isotope sampling were made on a nested basis at field and catchment (41 km2) scales for a series of events in the Wartburg catchment, South Africa. The nested catchment scale sampling was focused on control features in the stream network, including road crossings, farm dams and wetland zones. The analyzed stable water (δ18O and δ2H) isotopes results were used to interpret the connectivity of the contributing land forms and the stream network. The results reveal the dominant influences of farm dams and wetlands in limiting the downstream migration of sediment and nutrients for all but the most intense events. Certain events resulted in mixing in the dams and larger resultant outflow than inflow loads. These occurrences appear to be as a result of combinations of reservoir status, catchment antecedent conditions and rainfall depth and intensity. The nutrients loads between Bridge 1 and Bridge 2 stations reflect the bedrock control, where contributions from sugar cane hillslopes between these stations are not retained, even in the short wetland upstream of Bridge 2. Isotope analyses reveal that the headwaters, comprising 70% of the catchment area, contribute as little as 29% of the total catchment discharge, due to impoundments in this area. However, this contribution varies significantly for different events, reaching a maximum of 78% of the catchment discharge. It can therefore be concluded that nutrients and sediment migration in the Wartburg catchment is greatly influenced by connectivity. The δ18O and δ2H

  13. 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

  14. 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.

  15. Agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agriculture within the United States is varied and produces a large value ($200 billion in 2002) of production across a wide range of plant and animal production systems. Because of this diversity, changes in climate will likely impact agriculture throughout the United States. Climate affects crop, ...

  16. Water quality in the Scottish uplands: a hydrological perspective on catchment hydrochemistry.

    PubMed

    Soulsby, C; Gibbins, C; Wade, A J; Smart, R; Helliwell, R

    2002-07-22

    Land above 300 m covers approximately 75% of the surface of Scotland and most of the nation's major river systems have their headwaters in this upland environment. The hydrological characteristics of the uplands exert an important influence on the hydrochemistry of both headwater streams and downstream river systems. Thus, many of the spatial and temporal patterns in the chemical quality of surface waters are mediated by hydrological processes that route precipitation through upland catchments. These hydrological pathways also have an important influence on how the hydrochemistry of upland streams is responding to increasing pressures from environmental changes at the global and regional scales. At the present time, atmospheric deposition remains an issue in many parts of the Scottish uplands, where critical loads of acidity are exceeded, particularly in areas affected by increasing N deposition. Moreover, climatic change forecasts predict increasingly wetter, warmer and more seasonal conditions, which may modify the hydrochemical regimes of many river systems, particularly those with a strong snowmelt component. On a more localised scale, land management practices, including felling of commercial forests, expansion of native woodlands, agricultural decline and moorland management all have implications for the freshwater environment. Moreover, increasing public access to upland areas for a range of recreational activities have implications for water quality. Understanding the hydrology of the uplands, through integrated field and modelling studies, particularly of the hydrological pathways that regulate chemical transfers to streamwaters, will remain an important research frontier for the foreseeable future. PMID:12169013

  17. From natural to human-dominated floodplains - A Holocene perspective for the Dijle catchment, Belgium

    NASA Astrophysics Data System (ADS)

    Broothaerts, Nils; Verstraeten, Gert; Kasse, Cornelis; Bohncke, Sjoerd; Notebaert, Bastiaan; Vandenberghe, Jef

    2015-04-01

    Floodplain systems underwent important changes in many West and Central European catchments through the late Holocene. To better understand the relation between these landscape changes and human disturbances, geomorphic fieldwork needs to be complemented by quantitative measures of human impact in the landscape. In this study, we provide an holistic discussion in which we combine detailed data on floodplain changes with detailed data on human impact for the Dijle catchment (758 km²), Belgium. Human impact in the catchment was quantified based on statistical analysis of pollen data of six alluvial study sites. The results show that during the Neolithic Period, human impact was nearly absent and floodplains consisted of a strongly vegetated marshy environment where organic material accumulated, which is considered as the natural state of the floodplain. From the Bronze Age onwards, human impact increased and caused an increase in soil erosion and hillslope-floodplain connectivity. Consequently, sediment input in the floodplain system increased and floodplain geoecology changed towards an open floodplain dominated by clastic overbank deposits, mainly as the indirect result of an intensification of agricultural activities. Based on these data, a generalized model of floodplain development is presented: At the scale of the entire Dijle catchment, the gradual changes in floodplain morphology coincided with the gradually increasing human impact in the catchment, which suggests a linearity between the external forcing (human impact) and geomorphic response (floodplain change). However, at the narrow floodplains in the headwaters, the gradual increase in human impact contrasts with the abrupt change in floodplain geoecology, only triggered when human impact reached a threshold. Observed differences at catchment scale in time-lags and in the process-response model are attributed to differences in hillslope-floodplain connectivity, the location within the catchment and to

  18. 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

  19. Temporal and spatial variation of factors controlling metabolism and primary productivity in headwater streams

    NASA Astrophysics Data System (ADS)

    Johnson, S. L.; Argerich, A.; Ashkenas, L.

    2013-12-01

    Headwater streams account for 60-80 percent of stream-channel length in river networks, yet the variability among these streams is often simplified or neglected. Better understanding of the drivers and ways to characterize this variability are crucial as we evaluate the contributions of headwaters to downstream ecosystems. Metrics of ecosystem processes, such as whole stream metabolism, incorporate numerous factors across trophic levels and are considered fundamental descriptors of ecosystem function. Because metabolism integrates the activity of all organisms carrying out photosynthesis and aerobic respiration, it has been proposed as useful in evaluating contributions from multiple headwaters to downstream sites as well as measuring how stream communities respond to environmental changes. Here we explore the spatial and temporal variation in ecosystem metabolism and primary productivity across multiple forested headwater streams and their cumulative downstream sites. We also quantify the environmental factors that most influence these processes, including stream chemistry, temperature, chlorophyll a, benthic and algal biomass, fine sediment, forest cover and shading in 14 headwater streams and four downstream sites. This study occurred as part of the pre-treatment research in the Trask River Watershed Study, which is a multi-disciplinary, multi-year research project designed to evaluate the impacts of current forest management practices on headwater and downstream aquatic ecosystems in NW Oregon. Over the four years, we consistently found the headwater and downstream reaches to be highly heterotrophic with P:R ratios less than 0.05. However nutrient concentrations were not good predictors of metabolism rates or the biomass and activity of primary producers. Even though all sites were within a 3000 ha catchment and had similar amounts of forest cover and riparian shading, we observed high spatial variability in concentrations of stream nutrients (C, N, P) and

  20. 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).

  1. 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.

  2. Hydrology of Channelized and Natural Headwater Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding hydrology is paramount for optimal ecologic function and management of headwater streams. The objective of this study was to characterize and compare headwater streams within the Upper Big Walnut Creek watershed in Ohio. Two channelized and two unchannelized streams were instrumented w...

  3. 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. PMID:19029721

  4. PSYCHIC A process-based model of phosphorus and sediment mobilisation and delivery within agricultural catchments. Part 1: Model description and parameterisation

    NASA Astrophysics Data System (ADS)

    Davison, Paul S.; Withers, Paul J. A.; Lord, Eunice I.; Betson, Mark J.; Strömqvist, Johan

    2008-02-01

    SummaryPSYCHIC is a process-based model of phosphorus (P) and suspended sediment (SS) mobilisation in land runoff and subsequent delivery to watercourses. Modelled transfer pathways include release of desorbable soil P, detachment of SS and associated particulate P, incidental losses from manure and fertiliser applications, losses from hard standings, the transport of all the above to watercourses in underdrainage (where present) and via surface pathways, and losses of dissolved P from point sources. The model can operate at two spatial scales, although the scientific core is the same in both cases. At catchment scale, the model uses easily available national scale datasets to infer all necessary input data whilst at field scale, the user is required to supply all necessary data. The model is sensitive to a number of crop and animal husbandry decisions, as well as to environmental factors such as soil type and field slope angle. It is envisaged that the catchment-scale model would provide the first tier of a catchment characterisation study, and would be used as a screening tool to identify areas within the catchment which may be at elevated risk of P loss. This would enable targeted data collection, involving farm visits and stakeholder discussion, which would then be followed up with detailed field-scale modelling. Both tiers allow the effects of possible mitigation options at catchment scale (Tier 1) and field scale (Tier 2) to be explored. The PSYCHIC model framework therefore provides a methodology for identifying critical source areas of sediment and P transfer in catchments and assessing what management changes are required to achieve environmental goals.

  5. 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

  6. 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...

  7. Influence of Herbaceous Riparian Buffers on 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 buffers for headwater streams has been documented, but the ecological impacts of herbaceous ri...