Science.gov

Sample records for euroharp catchment network

  1. Collaborative knowledge in catchment research networks

    NASA Astrophysics Data System (ADS)

    Macleod, Christopher Kit

    2015-04-01

    There is a need to improve the production, sharing and use of collaborative knowledge of catchment systems through networks of researchers, policy makers and practitioners. This requires greater levels of systems based integrative research. In parallel to the growing realization that greater levels of collaborative knowledge in scientific research networks are required, a digital revolution has been taking place. This has been driven primarily by the emergence of distributed networks of computers and standards-based interoperability. The objective of this paper is to present the status and research needs for greater levels of systems based integrative research for the production, sharing and use of collaborative knowledge in catchment research networks. To enable increased levels of integrative research depends on development and application of digital technologies to improve collection, use and sharing of data and devise new knowledge infrastructures. This paper focuses on the requirements for catchment observatories that integrate existing and novel physical, social and digital networks of knowledge infrastructures. To support this focus, I present three leading international examples of collaborative networks of catchment researchers and their development of catchment observatories. In particular, the digital infrastructures they have developed to support collaborative knowledge in catchment research networks. These examples are from North America (NSF funded CUAHSI HIS) and from Europe (UK NERC funded EVOp and the German Helmholtz Association Centers funded TERENO/TEODOOR). These exemplars all supported advancing collaborative knowledge in catchment research networks through the development of catchment observatories. I will conclude by discussing the future research directions required for greater levels of production, sharing and use of collaborative knowledge in catchment research networks based on catchment systems science.

  2. Catchments network on badlands around Mediterranean area (RESOBAM)

    NASA Astrophysics Data System (ADS)

    Copard, Yoann; Lebouteiller, Caroline; Regues-Munoz, David; Latron, Jerome; Solé-Benet, Albert; Canton, Yolanda; Nadal-Romero, Estela; Della Seta, Marta; Rossi, Mauro; Capolongo, Domenico; Maquaire, Olivier; Forey, Estelle; Di-Giovanni, Christian; Gallart, Francesc; Delmonte, Maurizio; Vergari, Francesca; Massei, Nicolas; Torri, Dino

    2016-04-01

    Between 2013 and 2014, a network funded by MISTRALS-ENVIMED institution, was born around some instrumented catchments developing a badland-type morphology. This network has grouped 3 countries (France, Spain and Italy) with 12 scientific labs. RESOBAM has concerned two sites in France (Draix-Bléone and Vaches Noires), three in Spain (Vallcebre, Araguas and El Cautivo) and some sites in Italy (Tuscany, Basilicata). Main goal of this network was to federate the research around badlands at the European scale, by proposing some scientific topics as: sediment and water transports / budget, (bio)geochemical cycles, agricultural (farming), education, restoration, cultural heritage, soil conservation / biodiversity, climatic change etc. Other main interests were also to propose some common scientific projects and the development of students exchanges. This communication presents the synthesis of our four meetings held at Draix, Zaragoza, Almeriá and Rouen and some perspectives to continue this network.

  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. Connectivity of overland flow by drainage network expansion in a rain forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Beate; Zimmermann, Alexander; Turner, Benjamin L.; Francke, Till; Elsenbeer, Helmut

    2014-02-01

    Soils in various places of the Panama Canal Watershed feature a low saturated hydraulic conductivity (Ks) at shallow depth, which promotes overland-flow generation and associated flashy catchment responses. In undisturbed forests of these areas, overland flow is concentrated in flow lines that extend the channel network and provide hydrological connectivity between hillslopes and streams. To understand the dynamics of overland-flow connectivity, as well as the impact of connectivity on catchment response, we studied an undisturbed headwater catchment by monitoring overland-flow occurrence in all flow lines and discharge, suspended sediment, and total phosphorus at the catchment outlet. We find that connectivity is strongly influenced by seasonal variation in antecedent wetness and can develop even under light rainfall conditions. Connectivity increased rapidly as rainfall frequency increased, eventually leading to full connectivity and surficial drainage of entire hillslopes. Connectivity was nonlinearly related to catchment response. However, additional information on factors such as overland-flow volume would be required to constrain relationships between connectivity, stormflow, and the export of suspended sediment and phosphorus. The effort to monitor those factors would be substantial, so we advocate applying the established links between rain event characteristics, drainage network expansion by flow lines, and catchment response for predictive modeling and catchment classification in forests of the Panama Canal Watershed and in similar regions elsewhere.

  5. Establishment of a hydrological monitoring network in a tropical African catchment: An integrated participatory approach

    NASA Astrophysics Data System (ADS)

    Gomani, M. C.; Dietrich, O.; Lischeid, G.; Mahoo, H.; Mahay, F.; Mbilinyi, B.; Sarmett, J.

    Sound decision making for water resources management has to be based on good knowledge of the dominant hydrological processes of a catchment. This information can only be obtained through establishing suitable hydrological monitoring networks. Research catchments are typically established without involving the key stakeholders, which results in instruments being installed at inappropriate places as well as at high risk of theft and vandalism. This paper presents an integrated participatory approach for establishing a hydrological monitoring network. We propose a framework with six steps beginning with (i) inception of idea; (ii) stakeholder identification; (iii) defining the scope of the network; (iv) installation; (v) monitoring; and (vi) feedback mechanism integrated within the participatory framework. The approach is illustrated using an example of the Ngerengere catchment in Tanzania. In applying the approach, the concept of establishing the Ngerengere catchment monitoring network was initiated in 2008 within the Resilient Agro-landscapes to Climate Change in Tanzania (ReACCT) research program. The main stakeholders included: local communities; Sokoine University of Agriculture; Wami Ruvu Basin Water Office and the ReACCT Research team. The scope of the network was based on expert experience in similar projects and lessons learnt from literature review of similar projects from elsewhere integrated with local expert knowledge. The installations involved reconnaissance surveys, detailed surveys, and expert consultations to identify best sites. First, a Digital Elevation Model, land use, and soil maps were used to identify potential monitoring sites. Local and expert knowledge was collected on flow regimes, indicators of shallow groundwater plant species, precipitation pattern, vegetation, and soil types. This information was integrated and used to select sites for installation of an automatic weather station, automatic rain gauges, river flow gauging stations

  6. Predictive optimal control of sewer networks using CORAL tool: application to Riera Blanca catchment in Barcelona.

    PubMed

    Puig, V; Cembrano, G; Romera, J; Quevedo, J; Aznar, B; Ramón, G; Cabot, J

    2009-01-01

    This paper deals with the global control of the Riera Blanca catchment in the Barcelona sewer network using a predictive optimal control approach. This catchment has been modelled using a conceptual modelling approach based on decomposing the catchments in subcatchments and representing them as virtual tanks. This conceptual modelling approach allows real-time model calibration and control of the sewer network. The global control problem of the Riera Blanca catchment is solved using a optimal/predictive control algorithm. To implement the predictive optimal control of the Riera Blanca catchment, a software tool named CORAL is used. The on-line control is simulated by interfacing CORAL with a high fidelity simulator of sewer networks (MOUSE). CORAL interchanges readings from the limnimeters and gate commands with MOUSE as if it was connected with the real SCADA system. Finally, the global control results obtained using the predictive optimal control are presented and compared against the results obtained using current local control system. The results obtained using the global control are very satisfactory compared to those obtained using the local control.

  7. Complex networks, community structure, and catchment classification in a large-scale river basin

    NASA Astrophysics Data System (ADS)

    Fang, Koren; Sivakumar, Bellie; Woldemeskel, Fitsum M.

    2017-02-01

    This study introduces the concepts of complex networks, especially community structure, to classify catchments in large-scale river basins. The Mississippi River basin (MRB) is considered as a representative large-scale basin, and daily streamflow from a network of 1663 stations are analyzed. Six community structure methods are employed: edge betweenness, greedy algorithm, multilevel modularity optimization, leading eigenvector, label propagation, and walktrap. The influence of correlation threshold (i.e. spatial correlation in flow between stations) on classification (i.e. community formation) is examined. The consistency among the methods in classifying catchments is assessed, using a normalized mutual information (NMI) index. An attempt is also made to explain the community formation in terms of river network/branching and some important catchment/flow properties. The results indicate that the correlation threshold has a notable influence on the number and size of communities identified and that there is a high level of consistency in the performance among the methods (except for the leading eigenvector method at lower thresholds). The results also reveal that only a few communities combine to represent a majority of the catchments, with the 10 largest communities (roughly 4% of the total number of communities) representing almost two-thirds of the catchments. Community formation is found to be influenced not only by geographic proximity but also, more importantly, by the organization of the river network (i.e. main stem and subsequent branching). Some communities are found to exhibit a greater variability in catchment/flow properties within themselves when compared to that of the whole network, thus indicating that such characteristics are unlikely to be a significant influence on community grouping.

  8. Collaborative Catchment-Scale Water Quality Management using Integrated Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Zia, Huma; Harris, Nick; Merrett, Geoff

    2013-04-01

    Electronics and Computer Science, University of Southampton, United Kingdom Summary The challenge of improving water quality (WQ) is a growing global concern [1]. Poor WQ is mainly attributed to poor water management and outdated agricultural activities. We propose that collaborative sensor networks spread across an entire catchment can allow cooperation among individual activities for integrated WQ monitoring and management. We show that sharing information on critical parameters among networks of water bodies and farms can enable identification and quantification of the contaminant sources, enabling better decision making for agricultural practices and thereby reducing contaminants fluxes. Motivation and results Nutrient losses from land to water have accelerated due to agricultural and urban pursuits [2]. In many cases, the application of fertiliser can be reduced by 30-50% without any loss of yield [3]. Thus information about nutrient levels and trends around the farm can improve agricultural practices and thereby reduce water contamination. The use of sensor networks for monitoring WQ in a catchment is in its infancy, but more applications are being tested [4]. However, these are focussed on local requirements and are mostly limited to water bodies. They have yet to explore the use of this technology for catchment-scale monitoring and management decisions, in an autonomous and dynamic manner. For effective and integrated WQ management, we propose a system that utilises local monitoring networks across a catchment, with provision for collaborative information sharing. This system of networks shares information about critical events, such as rain or flooding. Higher-level applications make use of this information to inform decisions about nutrient management, improving the quality of monitoring through the provision of richer datasets of catchment information to local networks. In the full paper, we present example scenarios and analyse how the benefits of

  9. Multicriteria design of rain gauge networks for flash flood prediction in semiarid catchments with complex terrain

    NASA Astrophysics Data System (ADS)

    Volkmann, Till H. M.; Lyon, Steve W.; Gupta, Hoshin V.; Troch, Peter A.

    2010-11-01

    Despite the availability of weather radar data at high spatial (1 km2) and temporal (5-15 min) resolution, ground-based rain gauges continue to be necessary for accurate estimation of storm rainfall input to catchments during flash flood events, especially in mountainous catchments. Given economical considerations, a long-standing problem in catchment hydrology is to establish optimal placement of a small number of rain gauges to acquire data on both rainfall depth and spatiotemporal variability of intensity during extreme storm events. Using weather radar observations and a dense network of 40 tipping bucket rain gauges, this study examines whether it is possible to determine a reliable "best" set of rain gauge locations for the Sabino Canyon catchment near Tucson, Arizona, USA, given its complex topography and dominant storm track pattern. High-quality rainfall data are used to evaluate all possible configurations of a "practical" network having from one to four rain gauges. A multicriteria design strategy is used to guide rain gauge placement, by simultaneously minimizing the residual percent bias and maximizing the coefficient of correlation between the estimated and true mean areal rainfall and minimizing the normalized spatial mean squared error between the estimated and true spatiotemporal rainfall distribution. The performance of the optimized rain gauge network was then compared against randomly designed network ensembles by evaluating the quality of streamflows predicted using the Kinematic Runoff and Erosion (KINEROS2) event-based rainfall-runoff model. Our results indicate that the multicriteria strategy provided a robust design by which a sparse but accurate network of rain gauges could be implemented for semiarid basins such as the one studied.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. Estimation of regional recharge in the HOBE catchment using data from a distributed soil moisture network

    NASA Astrophysics Data System (ADS)

    Andreasen, M.; Andreasen, L. A.; Bircher, S.; Sonnenborg, T.; Jensen, K. H.

    2012-12-01

    The regional variation of recharge of ground water is dependent on a larger number of variables and conditions and is therefore difficult to quantify. In this study we have estimated regional recharge using data from a distributed network of soil moisture stations within the HOBE catchment. The network has been designed in an arrangement of three clusters along a long-term precipitation gradient and the stations have been distributed according to respective fractions of classes combining the prevailing land use, top- and subsoil conditions. At each of the 30 stations water content has been measured at three depths (0-5cm, 20-25cm and 50-55cm) for the period 2009-2011 at a temporal resolution of 30 minutes. The 1D soil-plant-atmosphere system model DAISY has been applied to each of the field locations to simulate the water balance of the root zone and the associated components of evapotranspiration and recharge. The 30 models have been formulated and parameterized using specific information on local climate, soil texture, land use and management. Each model was calibrated to the measured soil water content from the distributed network using the PEST (Parameter ESTimation) software. The calibrated parameters were saturated hydraulic conductivity Ks and van Genuchten parameter n as they were found most sensitive. The 30 sets of results were averaged to represent the mean conditions of the catchment. An effective parameterization was also determined by calibration against mean soil moisture and compared to the results obtained by using effective parameters using various averaging methods. The regional variation in groundwater recharge, actual evapotranspiration and soil water content in the catchment was dependent on land use. The simulated results showed that the largest recharge was found at the agricultural sites (554 mm/yr) and the lowest at the forested sites (257 mm/yr). Correspondingly, the highest actual evapotranspiration was found at the forested sites (614

  12. Effects of a network of sand-storage dams on the hydrology on catchment scale

    NASA Astrophysics Data System (ADS)

    Ertsen, Maurits; Strohschein, Paul; Onencan, Abby; van de Giesen, Nick

    2015-04-01

    Water conservation is a high priority in the drier areas of sub-Saharan Africa. Storage of water from the rainy season to the dry season, or even from wet years to dry years is highly important. Small multi-purpose sub-surface water reservoirs recharged through infiltration are used to provide water for humans, livestock and crops in the Kitui region in Kenya. The groundwater dams obstruct the natural flow of water in wet seasons or periods, and provide storage of water during dry seasons or periods. This paper links the hydrology of the sand-storage dams to human agency. When is a dam a success in hydrological terms? When it provides water every year? Every two years? How many months? What happens in very dry years? Obviously, water use will decrease the water volume and thus the water level upstream of the dam, but to what extent typically depends on the amounts used compared to the size of the dam and the water use itself. Longer-term effects on groundwater levels to be expected depend strongly on the way the water is used. Household water use and river banks infiltration increasing seasonal storage can go hand in hand. However, when water in dams is used for higher water demanding activities such as (motorized) irrigation, the infiltration effect into banks may be minimal. A dam can also be "too effective" and decrease water availability for water users further downstream. It is unlikely, however, that an individual farmer will effect on the downstream users of the resources he/she is tapping, but a network of dams as in Kitui may have considerable effect. Measurements indicate that only about 2% to 3% of the total yearly runoff within the catchment directly associated with a single dam is stored in its reservoir. Therefore only this small percentage of the total flow of a seasonal river with dams is blocked. The paper will detail these general concepts with a case study of the Kiindu catchment. The hydrology of the Kiindu catchment is dependent on different

  13. Regionalization of land-use impacts on streamflow using a network of paired catchments

    NASA Astrophysics Data System (ADS)

    Ochoa-Tocachi, Boris F.; Buytaert, Wouter; De Bièvre, Bert

    2016-09-01

    Quantifying the impact of land use and cover (LUC) change on catchment hydrological response is essential for land-use planning and management. Yet hydrologists are often not able to present consistent and reliable evidence to support such decision-making. The issue tends to be twofold: a scarcity of relevant observations, and the difficulty of regionalizing any existing observations. This study explores the potential of a paired catchment monitoring network to provide statistically robust, regionalized predictions of LUC change impact in an environment of high hydrological variability. We test the importance of LUC variables to explain hydrological responses and to improve regionalized predictions using 24 catchments distributed along the Tropical Andes. For this, we calculate first 50 physical catchment properties, and then select a subset based on correlation analysis. The reduced set is subsequently used to regionalize a selection of hydrological indices using multiple linear regression. Contrary to earlier studies, we find that incorporating LUC variables in the regional model structures increases significantly regression performance and predictive capacity for 66% of the indices. For the runoff ratio, baseflow index, and slope of the flow duration curve, the mean absolute error reduces by 53% and the variance of the residuals by 79%, on average. We attribute the explanatory capacity of LUC in the regional model to the pairwise monitoring setup, which increases the contrast of the land-use signal in the data set. As such, it may be a useful strategy to optimize data collection to support watershed management practices and improve decision-making in data-scarce regions.

  14. Applying the Fuzzy ARTMAP neural network for mapping erosive status in the Ria Formosa catchment (Portugal)

    NASA Astrophysics Data System (ADS)

    Granja Martins, F. M.; Neto Paixão, H. M.; Jordán, A.; Zavala, L. M.; Bellinfante, N.

    2012-04-01

    The study of the soil erosion risk is the starting point for development and sustainable land management. The intensity of soil erosion risk is conditioned by soil erodibility, slope, land use and vegetation cover. The objective of this work is mapping the erosive status of the Ria Formosa catchment using "Fuzzy ARTMAP" neural network. The study area is the catchment of Ria Formosa, which includes a shallow coastal lagoon with an area of about 16000 ha located in Algarve (southern Portugal). It is protected by EU and national laws, and is classified as a wetland of international importance under the RAMSAR convention. Previously to the construction of the artificial neuronal network model, it was necessary to establish the training areas (< 1% of total study area) in order to get information about lithofacies, land use, slope and the percentage of vegetation cover. These variables were assessed by supervised classification. Five classes of erosive status were obtained by the artificial neuronal network. These classes were compared with the map of erosive status elaborated with the methodology proposed by the Priority Action Plan/Regional Activity Centre (PAP/RAC, 1997). The differences between both methods were about 1% of the total area. Both maps were validated with field observations and analysis of aerial photographs.

  15. Estimation of snow covered area for an urban catchment using image processing and neural networks.

    PubMed

    Matheussen, B V; Thorolfsson, S T

    2003-01-01

    This paper presents a method to estimate the snow covered area (SCA) for small urban catchments. The method uses images taken with a digital camera positioned on top of a tall building. The camera is stationary and takes overview images of the same area every fifteen minutes throughout the winter season. The images were read into an image-processing program and a three-layered feed-forward perceptron artificial neural network (ANN) was used to calculate fractional snow cover within three different land cover types (road, park and roofs). The SCA was estimated from the number of pixels with snow cover relative to the total number of pixels. The method was tested for a small urban catchment, Risvollan in Trondheim, Norway. A time series of images taken during spring of 2001 and the 2001-2002 winter season was used to generate a time series of SCA. Snow covered area was also estimated from aerial photos. The results showed a strong correlation between SCA estimated from the digital camera and the aerial photos. The time series of SCA can be used for verification of urban snowmelt models.

  16. Catchment organisation, free energy dynamics and network control on critical zone water flows

    NASA Astrophysics Data System (ADS)

    Zehe, E.; Ehret, U.; Kleidon, A.; Jackisch, C.; Scherer, U.; Blume, T.

    2012-04-01

    From a functional point of view the catchment system is compiled by patterns of permeable and less permeable textural elements - soils and mother rock. Theses textural elements provide a mechanical stabile matrix for growth of terrestrial biota and soil formation. They furthermore organize subsurface storage of water against gravity, dissolved nutrients and heat. Storage against gravity is only possible because water acts as wetting fluid and is thus attracted by capillary forces in the pores space. Capillarity increases non-linearly with decreasing pore size and is zero at local saturation. The pore size distribution of a soil is thus characteristic of its capability to store water against losses such as drainage, evaporation and root extraction and at the same time a fingerprint of the work that has been performed by physical, chemical and biological processes to weather solid mother rock and form a soil. A strong spatial covariance of soil hydraulic properties within the same soil type is due to a fingerprint of strong spatial organization at small scales. Spatial organization at the hillslope scale implies the existence of a typical soil catena i.e. that hillslopes exhibit the same/ downslope sequence of different soils types. Textural storage elements are separated by strikingly self-similar network like structures, we name them flow structures. These flow structures are created in a self-reinforcing manner by work performed either by biota like earth worms and plant roots or by dissipative processes such as soil cracking and water/fluvial erosion. Regardless of their different origin connected flow structures exhibit a highly similar functioning and similar characteristics: they allow for high mass flows at small driving potential gradients because specific flow resistance along the network is continuously very small. This implies temporal stability even during small extremes, due to the small amount of local momentum dissipation per unit mass flow, as well

  17. Design of rain gauge networks for flash flood prediction: assessment based on spatial moments of catchment rainfall

    NASA Astrophysics Data System (ADS)

    Marra, F.; Zoccatelli, D.

    2012-04-01

    Despite the availability of weather radar data at high spatial (1 km2) and temporal (5-15 min) resolution, ground-based rain gauges continue to be necessary for accurate estimation of storm rainfall input to catchments during flash flood events, especially in terrain characterized by complex orography. A long-standing problem in catchment hydrology is to establish optimal placement and density of a rain gauge network to acquire data on both rainfall depth and spatiotemporal variability of intensity during extreme storm events. Using weather radar observations and a dense network of rain gauges, this study examines whether it is possible to determine a reliable "best" set of rain gauge locations for a number of catchments subject to flash floods observed in Europe. High-quality rainfall data are used to evaluate several configurations of a raingauge network with variable spatial densities. A methodology is used for the selection of raingauge sites, given a certain spatial density, which is based on the use of the spatial moments of catchment rainfall. This set of statistics quantifies the dependence existing between spatial rainfall organisation, basin morphology and runoff response. These statistics describe the spatial rainfall organisation in terms of position and dispersion as a function of the distance measured along the flow routing coordinate. Rainfall estimates obtained from the 'optimised' raingauge network are used as input for a distributed hydrological model. Results from these simulations are compared with those obtained by using the measured rainfall and with those obtained by estimating rainfall from randomly designed network ensembles. Our results show that indications from the optimization of the spatial moments of catchment rainfall may help to provide a robust design for rain gauge network design.

  18. Analysis of spatiotemporal soil moisture patterns at the catchment scale using a wireless sensor network

    NASA Astrophysics Data System (ADS)

    Bogena, Heye R.; Huisman, Johan A.; Rosenbaum, Ulrike; Weuthen, Ansgar; Vereecken, Harry

    2010-05-01

    Soil water content plays a key role in partitioning water and energy fluxes and controlling the pattern of groundwater recharge. Despite the importance of soil water content, it is not yet measured in an operational way at larger scales. The aim of this paper is to present the potential of real-time monitoring for the analysis of soil moisture patterns at the catchment scale using the recently developed wireless sensor network SoilNet [1], [2]. SoilNet is designed to measure soil moisture, salinity and temperature in several depths (e.g. 5, 20 and 50 cm). Recently, a small forest catchment Wüstebach (~27 ha) has been instrumented with 150 sensor nodes and more than 1200 soil sensors in the framework of the Transregio32 and the Helmholtz initiative TERENO (Terrestrial Environmental Observatories). From August to November 2009, more than 6 million soil moisture measurements have been performed. We will present first results from a statistical and geostatistical analysis of the data. The observed spatial variability of soil moisture corresponds well with the 800-m scale variability described in [3]. The very low scattering of the standard deviation versus mean soil moisture plots indicates that sensor network data shows less artificial soil moisture variations than soil moisture data originated from measurement campaigns. The variograms showed more or less the same nugget effect, which indicates that the sum of the sub-scale variability and the measurement error is rather time-invariant. Wet situations showed smaller spatial variability, which is attributed to saturated soil water content, which poses an upper limit and is typically not strongly variable in headwater catchments with relatively homogeneous soil. The spatiotemporal variability in soil moisture at 50 cm depth was significantly lower than at 5 and 20 cm. This finding indicates that the considerable variability of the top soil is buffered deeper in the soil due to lateral and vertical water fluxes

  19. Use of spatially distributed time-integrated sediment sampling networks and distributed fine sediment modelling to inform catchment management.

    PubMed

    Perks, M T; Warburton, J; Bracken, L J; Reaney, S M; Emery, S B; Hirst, S

    2017-02-06

    Under the EU Water Framework Directive, suspended sediment is omitted from environmental quality standards and compliance targets. This omission is partly explained by difficulties in assessing the complex dose-response of ecological communities. But equally, it is hindered by a lack of spatially distributed estimates of suspended sediment variability across catchments. In this paper, we demonstrate the inability of traditional, discrete sampling campaigns for assessing exposure to fine sediment. Sampling frequencies based on Environmental Quality Standard protocols, whilst reflecting typical manual sampling constraints, are unable to determine the magnitude of sediment exposure with an acceptable level of precision. Deviations from actual concentrations range between -35 and +20% based on the interquartile range of simulations. As an alternative, we assess the value of low-cost, suspended sediment sampling networks for quantifying suspended sediment transfer (SST). In this study of the 362 km(2) upland Esk catchment we observe that spatial patterns of sediment flux are consistent over the two year monitoring period across a network of 17 monitoring sites. This enables the key contributing sub-catchments of Butter Beck (SST: 1141 t km(2) yr(-1)) and Glaisdale Beck (SST: 841 t km(2) yr(-1)) to be identified. The time-integrated samplers offer a feasible alternative to traditional infrequent and discrete sampling approaches for assessing spatio-temporal changes in contamination. In conjunction with a spatially distributed diffuse pollution model (SCIMAP), time-integrated sediment sampling is an effective means of identifying critical sediment source areas in the catchment, which can better inform sediment management strategies for pollution prevention and control.

  20. Optimizing embedded sensor network design for catchment-scale snow-depth estimation using LiDAR and machine learning

    NASA Astrophysics Data System (ADS)

    Oroza, Carlos A.; Zheng, Zeshi; Glaser, Steven D.; Tuia, Devis; Bales, Roger C.

    2016-10-01

    We evaluate the accuracy of a machine-learning algorithm that uses LiDAR data to optimize ground-based sensor placements for catchment-scale snow measurements. Sampling locations that best represent catchment physiographic variables are identified with the Expectation Maximization algorithm for a Gaussian mixture model. A Gaussian process is then used to model the snow depth in a 1 km2 area surrounding the network, and additional sensors are placed to minimize the model uncertainty. The aim of the study is to determine the distribution of sensors that minimizes the bias and RMSE of the model. We compare the accuracy of the snow-depth model using the proposed placements to an existing sensor network at the Southern Sierra Critical Zone Observatory. Each model is validated with a 1 m2 LiDAR-derived snow-depth raster from 14 March 2010. The proposed algorithm exhibits higher accuracy with fewer sensors (8 sensors, RMSE 38.3 cm, bias = 3.49 cm) than the existing network (23 sensors, RMSE 53.0 cm, bias = 15.5 cm) and randomized placements (8 sensors, RMSE 63.7 cm, bias = 24.7 cm). We then evaluate the spatial and temporal transferability of the method using 14 LiDAR scenes from two catchments within the JPL Airborne Snow Observatory. In each region, the optimized sensor placements are determined using the first available snow raster for the year. The accuracy in the remaining LiDAR surveys is then compared to 100 configurations of sensors selected at random. We find the error statistics (bias and RMSE) to be more consistent across the additional surveys than the average random configuration.

  1. On the Derivation of Pan-European River Networks and Catchment Boundaries from a 250m DEM

    NASA Astrophysics Data System (ADS)

    Colombo, R.; Vogt, J. V.; Soille, P.; Paracchini, M. L.; de Jager, A. L.

    2003-04-01

    Mapping and characterisation of catchments and river courses for the European continent is of relevant interest to support the environmental monitoring activities of the European Environmental Agency (EEA) and for the implementation of the Water Framework Directive (WFD). At continental or global scale the river networks and associated catchments are generally derived from a set of standard DEM processing techniques, including pit filling, stream burning, and the calculation of flow direction and flow accumulation grids. The continental final river networks are generally detected by imposing a constant critical contributing area threshold, independently of widely varying landscape conditions. If the same critical area for all environments is assumed, the resulting drainage density does not reflect the real degree of dissection and the produced river map may be unrealistic. To overcome this limitation, we propose a classification of the landscape and we present a new approach to derive river networks and catchments over extended heterogeneous areas from medium resolution digital elevation data (250 m grid cell size) and environmental characteristics,. We show that the implementation of a European landscape characterisation, coupled with the analysis of the local slope versus contributing area represents a viable way for mapping the spatial variability of the river networks. Such landscape classification has been realised using a parametric model that keeps into account a set of five variables [annual rainfall (P), local relief (R), vegetation cover (V), soil transmissivity (T), and bedrock erodibility (E)] that quantify the environmental factors governing drainage density. The critical contributing area was derived for each landscape drainage density class by analysing the log-log plot of local slope contributing area relationships derived from the digital elevation data. The scaling break corresponding to the main valley networks was defined as the last inflection

  2. Integration of Volterra model with artificial neural networks for rainfall-runoff simulation in forested catchment of northern Iran

    NASA Astrophysics Data System (ADS)

    Kashani, Mahsa H.; Ghorbani, Mohammad Ali; Dinpashoh, Yagob; Shahmorad, Sedaghat

    2016-09-01

    Rainfall-runoff simulation is an important task in water resources management. In this study, an integrated Volterra model with artificial neural networks (IVANN) was presented to simulate the rainfall-runoff process. The proposed integrated model includes the semi-distributed forms of the Volterra and ANN models which can explore spatial variation in rainfall-runoff process without requiring physical characteristic parameters of the catchments, while taking advantage of the potential of Volterra and ANNs models in nonlinear mapping. The IVANN model was developed using hourly rainfall and runoff data pertaining to thirteen storms to study short-term responses of a forest catchment in northern Iran; and its performance was compared with that of semi-distributed integrated ANN (IANN) model and lumped Volterra model. The Volterra model was applied as a nonlinear model (second-order Volterra (SOV) model) and solved using the ordinary least square (OLS) method. The models performance were evaluated and compared using five performance criteria namely coefficient of efficiency, root mean square error, error of total volume, relative error of peak discharge and error of time for peak to arrive. Results showed that the IVANN model performs well than the other semi-distributed and lumped models to simulate the rainfall-runoff process. Comparing to the integrated models, the lumped SOV model has lower precision to simulate the rainfall-runoff process.

  3. An integrated approach for catchment delineation and conduit-network modeling in karst aquifers: application to a site in the Swiss tabular Jura

    NASA Astrophysics Data System (ADS)

    Malard, Arnauld; Jeannin, Pierre-Yves; Vouillamoz, Jonathan; Weber, Eric

    2015-11-01

    An essential issue in karst hydrology is the characterization of the hydrogeological flow systems, i.e., the delineation of catchment areas and the organization of the main flow paths (conduit network) feeding one or several outlets. The proposed approach provides an explicit way to sketch catchment areas, and to generate karst conduits on the basis of a three-dimensional (3D) conceptual model of the aquifer (KARSYS approach). The approach follows three main principles: (1) conduits develop according to the hydraulic gradient, which depends on the aquifer zonation, (2) conduits are guided by preferential guidance features (or inception horizons) prevailing in the unsaturated and saturated zones of the aquifer, and (3) conduits initiate on a regular basis below the autogenic zone of the catchment area. This approach was applied to a site in the Swiss Jura as a base for the assessment of flood-hazard risks. The resulting model proposes a new delineation of the system catchment area and appears fairer regarding hydrological measurements than previous interpretations, which under-estimated the catchment area by about 20 %. Furthermore, the proposed conduit network for the whole aquifer is also consistent with local cave surveys and dye-tracing observations. These interesting results demonstrate that the combination of this approach with the KARSYS 3D model provides an integrated and effective way for the characterization of karst-flow systems.

  4. The role of a dambo in the hydrology of a catchment and the river network downstream

    NASA Astrophysics Data System (ADS)

    von der Heyden, Constantin J.; New, Mark G.

    Dambos are shallow, seasonally inundated wetlands and are a widespread landform in Central and Southern Africa. Owing to their importance in local agriculture and as a water resource, the hydrology of dambos is of considerable interest: varied, and sometimes contradictory, hydrological characteristics have been described in the literature. The issues in contention focus on the role of the dambo in (i) the catchment evapotranspiration (ET) budget, (ii) flood flow retardation and attenuation, and (iii) sustaining dry season flow to the river down-stream. In addition, both rainfall and groundwater have been identified as the dominant source of water to the dambo and various hydrogeological models have been proposed to describe the hydrological functions of the landform. In this paper, hydrological and geochemical data collected over a full hydrological year are used to investigate and describe the hydrological functions of a dambo in north-western Zambia. The Penman estimate of wetland ET was less than the ET from the miombo-wooded interfluve and the wetland has been shown to have little effect on flood flow retardation or attenuation. Discharge of water stored within the wetland contributed little to the dry season flow from the dambo, which was sustained primarily by groundwater discharge. Flow in a perched aquifer within the catchment soils contributed a large portion of baseflow during the rains and early dry season. This source ceased by the mid dry season, implying that the sustained middle to late dry season streamflow from the wetland is through discharge of a deeper aquifer within the underlying regolith or bedrock. This hypothesis is tested through an analysis of groundwater and wetland geochemistry. Various physical parameters, PHREEQC model results and end member mixing analysis (EMMA) suggest strongly that the deep Upper Roan dolomite aquifer is the source of sustained discharge from the wetland.

  5. Water level and response time of rivers during flash floods derived from a nested network in the Claduègne Mediterranean catchment (43 km2)

    NASA Astrophysics Data System (ADS)

    Gonzalez-Sosa, Enrique; Braud, Isabelle; Molinié, Gilles; Nord, Guillaume; Vandervaere, Jean-Pierre; Uber, Magdalana

    2016-04-01

    Flash floods are natural hazards that affect the Mediterranean region. They are caused by intense rainfall events but catchments characteristics are also influential on the hydrological response. In order to study the respective roles of rainfall, land use, geology and soil moisture on this hydrological response at various scales, a high space-time resolution hydrometeorological experimental monitoring system was set in the Mediterranean Claduègne catchment (43 km2), located in the Ardèche catchment, south-east France between 2011 and 2014 (Braud et al., 2014; Nord et al., in prep). Rainfall was monitored using a high resolution rainfall network (Hpiconet) composed of 21 rain gauges with 1 min time step covering an area of about 100 km2. The monitoring of surface hydrology include water level measurements at the outlet of 10 subcatchments ranging from 0.2 to 2.2 km2 and hydrometric measurements (water level, discharge) at the outlet of 3 catchments (Gazel: 3.4 km², SJ1: 12 km² and Claduègne: 43 km²). The 10 subcatchments as well as the Gazel and SJ1 catchments are all embedded within the Claduègne catchments. The location of the 10 subcatchments was chosen to sample different combinations of geology, land use and pedology within the Claduègne catchment. In particular, 4 of these subcathments are located within the Gazel catchment and 2 are located within the SJ1 catchment. Soil moisture data with a 20 minutes time step at depths 10cm, 20-25 and 30-50 cm is also available at nine locations, sampling different combinations of land use and geology. Catchment rainfall was computed from the Hpiconet data for each sub-catchment and all rainfall events using the Thiessen polygons method. The corresponding hydrological response was extracted for the whole data sets. For each event, rainfall characteristics describing rainfall amount and intensity, antecedent rainfall (and thus initial soil moisture) were computed. When a hydrological response was observed, reaction

  6. A mountain environmental virtual observatory (Mountain-EVO) to support participatory monitoring in a network of Andean catchments

    NASA Astrophysics Data System (ADS)

    Buytaert, Wouter; Ochoa Tocachi, Boris; De Bievre, Bert; Zulkafli, Zed

    2015-04-01

    The tropical Andes are a hotspot of environmental change. The combination of dramatic land-use change with global climate change, demographic growth, and increasing water demand is causing extreme pressures on water resources. This is of particular concern to rural upland communities. They are facing a double challenge of maintaining their own livelihoods with dwindling natural resources, and at the same time supporting downstream ecosystem services such as a well buffered stream flow and good water quality. This challenge is complicated further by the acute lack of data on the hydrological functioning of Andean catchments. The factors controlling their hydrological response are extremely variable in space and time, including meteorological forcing, land cover types, soil properties and geology. This makes it very difficult to predict accurately the impact of human activities such as land use, ecosystem management, and watershed investments. Such predictions are essential for policy-making and sustainable ecosystem management. To tackle the issue of hydrological data scarcity in the tropical Andes, an initiative was set up to implement a network of hydrological monitoring of upland catchments in a pairwise fashion. Using a trading-space-for-time approach, the initiative intends to use these data to improve predictions about the impact of land-use changes and other ecosystem management practices on the hydrological response. Currently, over 25 catchments are being monitored for precipitation and streamflow in 9 sites located in Bolivia, Peru, Ecuador, and Venezuela. The sites are supported by local stakeholders and communities in a participatory monitoring scheme that otherwise would be impractical or prohibitively expensive. To overcome the technical challenges of monitoring hydrological variables in remote mountain areas, the initiative has set up a web-based infrastructure to support local technicians and stakeholders. Additionally, using open data standards such

  7. Comparative analyses of factors determining soil erosion rates based on network of Mediterranean monitored catchments for the innovative, adaptive and resilient agriculture of the future

    NASA Astrophysics Data System (ADS)

    Smetanová, Anna; Le Bissonnais, Yves; Raclot, Damien; Perdo Nunes, João; Licciardello, Feliciana; Mathys, Nicolle; Latron, Jérôme; Rodríguez Caballero, Emilio; Le Bouteiller, Caroline; Klotz, Sébastien; Mekki, Insaf; Gallart, Francesc; Solé Benet, Albert; Pérez Gallego, Nuria; Andrieux, Patrick; Jantzi, Hugo; Moussa, Roger; Planchon, Olivier; Marisa Santos, Juliana

    2015-04-01

    In order to project the soil erosion response to climate change in the fragile Mediterranean region it is inevitable to understand its existing patterns. Soil erosion monitoring on a catchment scale enables to analyse temporal and spatial variability of soil erosion and sediment delivery, while the integrating study of different catchments is often undertaken to depicther the general patterns. In this study, eight small catchments (with area up to 1,32 km2), representative for the western part of the Mediterranean region (according to climate, bedrock, soils and main type of land use) were compared. These catchments, grouped in the R-OS Med Network were situated in France (3), Spain (2), Portugal (1), Italy (1) and Tunisia (1). The average precipitation ranged between 236 to 1303 mm·a-1 and mean annual sediment yield varied 7.5 to 6900 Mg·km-2·a-1. The complex databes was based on more than 120 years of hydrological and sediment data, with series between 3 and 29 years long. The variability of sediment data was described on annual and monthly basis. The relationship between the sediment yield and more than 35 factors influencing the sediment yield including the characteristics of climate, topography, rainfall, runoff, land use, vegetation and soil cover, connectivity and dominant geomorphic processes, was studied. The preliminary results confirmed the differences in rainfall, runoff and sediment response, and revealed both the similarities and differences in soil erosion responses of the catchments. They are further dependent on the variability of factors themselves, with important contribution of the state of soil properties, vegetation cover and land use. Anna Smetanová has received the support of the European Union, in the framework of the Marie-Curie FP7 COFUND People Programme, through the award of an AgreenSkills' fellowship (under grant agreement n° 267196)

  8. The influence of drainage networks on patterns of soil respiration in a desert catchment.

    PubMed

    Sponseller, Ryan A; Fisher, Stuart G

    2008-04-01

    Hydrologic flow and connectivity act as important determinants of ecological pattern and process in heterogeneous landscapes. Here we examine how the routing of water through the drainage network of an upper Sonoran Desert basin influences landscape patterns of soil respiration (SR) at both seasonal and event-based timescales. At seasonal timescales, SR varied up to 13-fold with downstream position in the drainage network, and annual estimates of CO2 efflux ranged from 185 g C x m(-2) x yr(-1) to 1190 g C x m(-2) x yr(-1) for sites arrayed along the same flow path. Spatial patterns of SR were unrelated to the carbon and water content of surface soils, but rather tracked changes in plant size and productivity, which in turn reflect downstream increases in groundwater availability. The relative importance of precipitation and temperature as drivers of SR also changed with landscape position, with the latter becoming more important in downstream locations. At the scale of individual precipitation events, SR increased up to 30-fold upon rewetting but typically returned to background levels within 24 h, even when soil moisture remained elevated. Unlike patterns observed at seasonal scales, event-based losses of CO2 varied across the landscape as a function of the organic-matter content in surface soils. Results from labile carbon amendments confirm that CO2 losses following precipitation pulses are initially constrained by substrate availability, not soil drying. By mediating spatial patterns of vegetation structure and soil resource availability, drainage networks represent an important physical template upon which belowground processes are organized in desert basins.

  9. 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

  10. Network analysis of sediment cascades derived from a digital geomorphological map - an example from the Gradenbach catchment (Schober Mountains, Austrian Alps)

    NASA Astrophysics Data System (ADS)

    Götz, Joachim; Heckmann, Tobias; Schrott, Lothar

    2013-04-01

    A detailed geomorphological map of the Gradenbach catchment (32 km², Schober Mountains, Austrian Alps) is presented that focuses on the sediment transfer system. Data were acquired in the field and by the interpretation of orthophotos, LIDAR data and derivatives (slope, curvature, aspect, shaded relief). The resulting digital geomorphological map contains polygon representations of landforms together with their morphometric parameters and an assessment of recent geomorphic activity. Special attention was paid to landform coupling, i.e. an additional table was constructed that indicates recently observable coupling between specific landforms (based on their ID in the database). From these data, we can obtain sediment cascades as a succession of coupled landforms along which sediment transfer occurs through the activity of various geomorphic processes. Based on this digital landform inventory the sediment transfer system is analysed using graph theory. As a rather new approach in geomorphology (already established within several disciplines; e.g. hydrology, biogeography), graph theory provides a promising framework for connectivity analysis in geomorphologic systems and powerful tools to visualise and analyse catchment-wide sediment transfer networks. Since the concept is arbitrarily scalable it can be applied to discrete land surface units (e.g. mapped landforms) or to continuous surface data (e.g. grid cells). In combination with geomorphological mapping, the concept allows for the (abstracted) visualisation of complex coupling relationships between multiple sediment storage landforms. Graph networks can be analysed at the level of nodes (e.g. the number of incoming and/or outgoing edges and their character as sediment source, sink or link), edges (e.g. importance within the network as conveyors of sediment from different sources), pathways (e.g. edge sequences leading to the catchment outlet or to storage landforms; these can be termed sediment cascades), or the

  11. Collective arrangements and social networks: Coping strategies for the poor households in the Great Ruaha Catchment in Tanzania

    NASA Astrophysics Data System (ADS)

    Kadigi, Reuben M. J.; Mdoe, N. S. Y.; Ashimogo, G. C.

    Access to water and land resources underpins the socio-economic fabric of many societies in the Southern Africa region, which is characterized broadly as underdeveloped with widespread food insecurity, exacerbated by persistent droughts, erratic rainfalls and increasing human populations. The availability of land and water resources is increasingly diminishing and becoming a stumbling block to the development of the agrarian societies in the region. The poor households have in turn adopted new livelihood coping mechanisms but little research has been done to assess the effectiveness of these ‘instruments’. Consequently, the concepts of sustainable water resources management and agricultural development have remained elusive and poorly understood by policy makers as well as by water resources planners and managers. Recognizing this, a study was conducted between 2002 and 2005 under the RIPARWIN (Raising Irrigation Productivity and Releasing Water for Intersectoral Needs) project to assess the spatial dynamics of livelihood capital, vulnerability and coping strategies for the poor agrarian households in the Upper Great Ruaha River Catchment (GRRC) in Tanzania. The results of analysis showed an array of livelihood platforms and institutional contexts that act to shape the existing livelihood typologies in the GRRC. In addition, the results showed a gradual increase in household vulnerability from upstream to downstream, particularly in terms of access to physical and natural assets. Vulnerability was found to be directly associated with the number of dependants. The female-headed households were relatively more likely to be vulnerable than the male-headed households (cf. probabilities of 27% and 21%, respectively). The value of collective arrangements and drawing on social networks crosscut all social strata and ranked as the most common livelihood strategy. This suggests that the scope for reducing vulnerability among the poor households in the GRRC critically

  12. Catchment-flowline network and selected model inputs for an enhanced and updated spatially referenced statistical assessment of dissolved-solids load sources and transport in streams of the Upper Colorado River Basin

    USGS Publications Warehouse

    Buto, Susan G.; Spangler, Lawrence E.; Flint, Alan L.; Flint, Lorraine E.

    2017-01-01

    This USGS data release consists of the synthetic stream network and associated catchments used to develop spatially referenced regressions on watershed attributes (SPARROW) model of dissolved-solids sources and transport in the Upper Colorado River Basin as well as geology and selected Basin Characterization Model (BCM) data used as input to the model.

  13. Integrated observation and modelling of runoff and sediments across different compartments of semi-arid catchments and channel networks

    NASA Astrophysics Data System (ADS)

    Bronstert, Axel; Ramon, Batalla; Araújo José C., De; da Costa Alexandre, Cunha; Till, Francke; Andreas, Güntner; Jose, Lopez-Tarazon; George, Mamede; Müller Eva, N.

    2010-05-01

    About one-third of the global population currently lives in countries which experience conditions of water stress. Such regions, often located within dryland ecosystems, are exposed to the hazard that the available freshwater resources fail to meet the water demand in domestic, agricultural and industrial sectors. Water availability often relies on the retention of river runoff in artificial lakes and reservoirs. However, the water storage in reservoirs is often adversely affected by sedimentation as a result of soil erosion. Erosion of the land surface due to natural or anthropogenic reasons and deposition of the eroded material in reservoirs threatens the reliability of reservoirs as a source of water supply. To sustain future water supply, a quantification of the sediment export from large dryland catchments becomes indispensable. A comprehensive modelling framework for water and sediment transport at the meso-scale, with a particular focus on dryland regions, has been developed from a German, Catalonian and Brazilian team during the last decade. It includes novel components for erosion from erosion-prone hillslopes, sediment transfer, retention and re-mobilization through the river system and sediment distribution, trapping and transfer through a reservoir. The parameterisation for pilot catchments is based on field monitoring campaigns of water and sediment fluxes, the analysis of land-use patterns, and the identification of the sediment hot spots through remotely sensed data. We present results of erosion-prone landscape units, the role of sediment transport in the river system, and the sedimentation processes in reservoirs. The modelling studies demonstrate the wide range of environmental problems where the model may be employed to develop sustainable management strategies for land and water resources. Evaluation of scenarios (land use, climate change) combined with an integrated assessment of options in reservoir management opens the opportunity to address

  14. The effect of social networks and social support on mental health services use, following a life event, among the Baltimore Epidemiologic Catchment Area cohort.

    PubMed

    Maulik, Pallab K; Eaton, William W; Bradshaw, Catherine P

    2011-01-01

    The study examined the association between life events and mental health services use, accounting for social networks and social support. Main and stress-buffering effects were estimated using longitudinal data from the Baltimore Epidemiologic Catchment Area cohort (1,920 participants in 1993-1996, of whom 1,071 were re-interviewed in 2004-2005). Following a life event, the odds of using general medical services were increased by almost 50% when there was increased social support from spouse/partner (referral function). The odds of using mental health services within general health setup were reduced by 60% when there was increased support from relatives (stress-reduction function). Increased social support from friends and relatives was associated with a 40-60% decreased odds of using specialty psychiatric services after experiencing different life events (stress-reduction function). Overall, social support rather than social networks were more strongly associated with increased mental health service use following a life event. The implications for service delivery and program development are discussed.

  15. The Immatsiak network of groundwater wells in a small catchment basin in the discontinuous permafrost zone of Northern Quebec, Canada: A unique opportunity for monitoring the impacts of climate change on groundwater (Invited)

    NASA Astrophysics Data System (ADS)

    Fortier, R.; Lemieux, J.; Molson, J. W.; Therrien, R.; Ouellet, M.; Bart, J.

    2013-12-01

    During a summer drilling campaign in 2012, a network of nine groundwater monitoring wells was installed in a small catchment basin in a zone of discontinuous permafrost near the Inuit community of Umiujaq in Northern Quebec, Canada. This network, named Immatsiak, is part of a provincial network of groundwater monitoring wells to monitor the impacts of climate change on groundwater resources. It provides a unique opportunity to study cold region groundwater dynamics in permafrost environments and to assess the impacts of permafrost degradation on groundwater quality and availability as a potential source of drinking water. Using the borehole logs from the drilling campaign and other information from previous investigations, an interpretative cryo-hydrogeological cross-section of the catchment basin was produced which identified the Quaternary deposit thickness and extent, the depth to bedrock, the location of permafrost, one superficial aquifer located in a sand deposit, and another deep aquifer in fluvio-glacial sediments and till. In the summer of 2013, data were recovered from water level and barometric loggers which were installed in the wells in August 2012. Although the wells were drilled in unfrozen zones, the groundwater temperature is very low, near 0.4 °C, with an annual variability of a few tenths of a degree Celsius at a depth of 35 m. The hydraulic head in the wells varied as much as 6 m over the last year. Pumping tests performed in the wells showed a very high hydraulic conductivity of the deep aquifer. Groundwater in the wells and surface water in small thermokarst lakes and at the catchment outlet were sampled for geochemical analysis (inorganic parameters, stable isotopes of oxygen (δ18O) and hydrogen (δ2H), and radioactive isotopes of carbon (δ14C), hydrogen (tritium δ3H) and helium (δ3He)) to assess groundwater quality and origin. Preliminary results show that the signature of melt water from permafrost thawing is observed in the

  16. A new perspective on catchment storage gained from a nested catchment experiment in Luxembourg (Europe)

    NASA Astrophysics Data System (ADS)

    Pfister, Laurent; Klaus, Julian; Hissler, Christophe; François Iffly, Jean; Gourdol, Laurent; Martinez-Carreras, Nuria; McDonnell, Jeffrey J.

    2014-05-01

    Recent hydrological process research focussed on how much water a catchment can store and how these catchments store and release water. Storage can be a valuable metric for catchment description, inter-comparison, and classification. Further storage controls catchment mixing, non-linearities in rainfall-runoff transformation and eco-hydrological processes. Various methods exist to determine catchment storage (e.g. natural tracer, soil moisture and groundwater data, hydrological models). Today it remains unclear what parts of the catchment storage are measured with the different models. Here we present a new hydrometric approach to answer the question how much water a catchment can store. We tested our approach in a dense hydro-climatological monitoring network that encompasses 16 recording streamgauges and 21 pluviographs in the Alzette River basin in Luxembourg (Europe). Catchment scales are ranging from 0.47 to 285 km2 and they have clean- and mixed combinations of distinct geologies ranging from schists to marls, sandstone, dolomite and limestone. Previous investigations in the area of interest have shown that geology largely controls winter runoff coefficients. Here, we focus at how catchment geology is ultimately affecting catchment storage. We used the approach of Sayama et al. (2011) to compute catchment dynamic storage changes for each winter season over the period 2002-2012 (based on precipitation as input; discharge and evapotranspiration as output). We determined dynamic storage changes for each winter semester (October to March) in all 16 catchments over the period 2002-2012. At the beginning of each hydrological winter season, all catchments showed similar trends in storage change. A few weeks into the winter season, catchments with lowest permeability (e.g. marls) started to plateau. The highest storage values were reached several months later in the season in catchments dominated by permeable substrate (e.g. sandstone). For most catchments, we found

  17. What makes catchment management groups "tick"?

    PubMed

    Oliver, P

    2001-01-01

    The work of catchment management groups throughout Australia represents a significant economic and social investment in natural resource management. Institutional structures and policies, the role of on-ground coordinators, facilitation processes, citizen participation and social capital are critical factors influencing the success of catchment management groups. From a participant-researcher viewpoint, this paper signposts research directions and themes that are being pursued from the participant/coordinator, catchment group, and lead government/non-government agency perspective on the influence of these factors on the success of a catchment management group in the Pumicestone Region of Southeast Queensland, Australia. Research directions, themes and discussion/reflection points for practitioners include--the importance of understanding milieu; motivation; success; having fun; "networking networks"; involvement of "nontraditional" stakeholders; development of stakeholder/participant partnerships; learning from other practitioners; methods of stakeholder/participant representation; evaluation; the need for guiding principles or philosophy; the equivalence of planning, implementation, evaluation, and resourcing; catchments as fundamental units of Nature; continuity of support for groups; recognising a new role for government; working with existing networks; and the need for an eclectic approach to natural resource management.

  18. On Radar Rainfall, Catchment Runoff and the Response Scale

    NASA Astrophysics Data System (ADS)

    Morin, E.; Goodrich, D. C.; Gao, X.; Sorooshian, S.

    2001-12-01

    The general research hypothesis is that: "a rainfall event, extreme at a specific scale, has the potential to generate an extreme runoff event in a catchment, which characterized by this response scale". In the presented study, which is a first step in testing this hypothesis, we examine if catchments have a stable response scale in the above context. For that purpose, we compare maximum storm rainfall intensities at different time and space scales with runoff peak discharges in order to determine at what scale these two variables are best related to each other. Three types of rainfall variable are tested: 1) gage rainfall intensity, 2) radar rainfall intensity, and 3) radar reflectivity. Initial results are available for the Walnut Gulch Experimental Catchment, a 150-km2 semi-arid catchment, located in southern Arizona. The catchment is well equipped with dense networks of rainfall and runoff gages. Radar data are also available for the catchment from the Tucson NEXRAD system. Preliminary results indicate a response scale in the order of 6-km and 2-hours for the 150-km2 catchment and for the 126- and 94-km2 sub-catchments. The response scale of a 25-km2 sub-catchment is reduced to 1-km and 20-minutes. The three types of rainfall variable tested point to the same response scale. As mentioned, the above results are initial and based on a limited number of events. We are investigating this hypothesis on a larger number of events as well as additional catchments.

  19. Water Catchment and Storage Monitoring

    NASA Astrophysics Data System (ADS)

    Bruenig, Michael; Dunbabin, Matt; Moore, Darren

    2010-05-01

    Sensors and Sensor Networks technologies provide the means for comprehensive understanding of natural processes in the environment by radically increasing the availability of empirical data about the natural world. This step change is achieved through a dramatic reduction in the cost of data acquisition and many orders of magnitude increase in the spatial and temporal granularity of measurements. Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) is undertaking a strategic research program developing wireless sensor network technology for environmental monitoring. As part of this research initiative, we are engaging with government agencies to densely monitor water catchments and storages, thereby enhancing understanding of the environmental processes that affect water quality. In the Gold Coast hinterland in Queensland, Australia, we are building sensor networks to monitor restoration of rainforest within the catchment, and to monitor methane flux release and water quality in the water storages. This poster will present our ongoing work in this region of eastern Australia. The Springbrook plateau in the Gold Coast hinterland lies within a World Heritage listed area, has uniquely high rainfall, hosts a wide range of environmental gradients, and forms part of the catchment for Gold Coast's water storages. Parts of the plateau are being restored from agricultural grassland to native rainforest vegetation. Since April 2008, we have had a 10-node, multi-hop sensor network deployed there to monitor microclimate variables. This network will be expanded to 50-nodes in February 2010, and to around 200-nodes and 1000 sensors by mid-2011, spread over an area of approximately 0.8 square kilometers. The extremely dense microclimate sensing will enhance knowledge of the environmental factors that enhance or inhibit the regeneration of native rainforest. The final network will also include nodes with acoustic and image sensing capability for

  20. Catchment scale multi-objective flood management

    NASA Astrophysics Data System (ADS)

    Rose, Steve; Worrall, Peter; Rosolova, Zdenka; Hammond, Gene

    2010-05-01

    Rural land management is known to affect both the generation and propagation of flooding at the local scale, but there is still a general lack of good evidence that this impact is still significant at the larger catchment scale given the complexity of physical interactions and climatic variability taking place at this level. The National Trust, in partnership with the Environment Agency, are managing an innovative project on the Holnicote Estate in south west England to demonstrate the benefits of using good rural land management practices to reduce flood risk at the both the catchment and sub-catchment scales. The Holnicote Estate is owned by the National Trust and comprises about 5,000 hectares of land, from the uplands of Exmoor to the sea, incorporating most of the catchments of the river Horner and Aller Water. There are nearly 100 houses across three villages that are at risk from flooding which could potentially benefit from changes in land management practices in the surrounding catchment providing a more sustainable flood attenuation function. In addition to the contribution being made to flood risk management there are a range of other ecosystems services that will be enhanced through these targeted land management changes. Alterations in land management will create new opportunities for wildlife and habitats and help to improve the local surface water quality. Such improvements will not only create additional wildlife resources locally but also serve the landscape response to climate change effects by creating and enhancing wildlife networks within the region. Land management changes will also restore and sustain landscape heritage resources and provide opportunities for amenity, recreation and tourism. The project delivery team is working with the National Trust from source to sea across the entire Holnicote Estate, to identify and subsequently implement suitable land management techniques to manage local flood risk within the catchments. These

  1. Exploring links between tectonics, catchment morphology and hydrographs across Europe

    NASA Astrophysics Data System (ADS)

    Vanmaercke, Matthias; Campforts, Benjamin; Van Ruyskensvelde, Glenn; Poesen, Jean

    2016-04-01

    A growing number of studies show that contemporary catchment sediment yields (SY, [t/km²/y]) are strongly correlated to patterns of seismic activity at regional to continental scales. Nonetheless, the mechanisms explaining these correlations are still poorly understood. Seismicity may increase SY by triggering landslides or weakening the surface lithology. On the other hand seismicity can be considered as a proxy for tectonic movements, while there is a growing consensus that tectonics exert an important influence on catchment morphology. This morphology influences the properties of runoff events (e.g. peak discharge, stream power). Given the large influence of large runoff events on annual SY, it is therefore possible that observed correlations between SY and seismicity are (at least partly) attributable to tectonic influences on catchment morphology. We test this hypothesis by investigating links between runoff hydrographs and patterns in catchment properties at a European scale using numerous catchment indices such as the slope, channel steepness, circularity, drainage length, river network topology, etc. From DEMs with a resolution of ca. 100m we randomly delineated over 5000 catchments across Europe with an area of 90 to 100 km². For each of these catchments, we simulated a runoff hydrograph, using a simple Hortonian runoff model that routes water through the catchment based on previously proposed flow velocity equations. We made abstraction of rainfall patterns, lithology, land use and all factors other than topography. Hence, the hydrographs only reflect the influence of the morphological properties of the catchments and allow for comparisons. First results show that, apart from average catchment slope, there are very few regional patterns in catchment morphological properties that may significantly affect hydrographs. In some tectonically active regions, channel slopes are slightly steeper compared to catchments with the same average catchment slope in

  2. Characterizing streamflow generation in Alpine catchments

    NASA Astrophysics Data System (ADS)

    Chiogna, Gabriele; Cano Paoli, Karina; Bellin, Alberto

    2016-04-01

    Developing effective hydrological models for streamflow generation in Alpine catchments is challenging due to the inherent complexity of the intertwined processes controlling water transfer from hillslopes to streams and along the river network. With water discharge as the sole observational variable it is impossible to differentiate between different streamflow sources, and modelling activity is often limited to simplified phenomenological rainfall-runoff models. This study focuses on quantifying streamflow sources at different temporal scales and the associated uncertainty by using natural tracer data (electrical conductivity, oxygen and hydrogen stable isotopes ratios) as observational variables supplementing streamflow measurements. We determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy and we separate contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. Furthermore, we identify a seasonal control on the effect of storm events. The catchment responded rapidly to precipitation events in early autumn, it was unaffected by precipitation events in early spring, while runoff generation was enhanced by snow melting in late autumn. Air temperature is identified as the main controlling parameter, in addition to precipitation. Two-component mixing analysis showed that the relative contribution of new water, which can contribute up to 75% of total streamflow, is very rapid. Only two hours time-lag was observed between the beginning of the precipitation event and the emergence of a significant contribution of new water. These results evidence the relevance of mixing between pre-event and event water in the Vermigliana catchment, and in similar high elevation Alpine catchments. This study provides new insights on the dynamics of streamflow generation in Alpine catchments and a

  3. Heterogeneity in catchment properties: a case study of Grey and Buller catchments, New Zealand

    NASA Astrophysics Data System (ADS)

    Shankar, U.; Pearson, C. P.; Nikora, V. I.; Ibbitt, R. P.

    The scaling behaviour of landscape properties, including both morphological and landscape patchiness, is examined using monofractal and multifractal analysis. The study is confined to two neighbouring meso-scale catchments on the west coast of the South Island of New Zealand. The catchments offer a diverse but largely undisturbed landscape with population and development impacts being extremely low. Bulk landscape properties of the catchments (and their sub-basins) are examined and show that scaling of stream networks follow Hack’s empirical rule, with exponents ˜0.6. It is also found that the longitudinal and transverse scaling exponents of stream networks equate to νl ≈0.6 and νw≈ 0.4, indicative of self-affine scaling. Catchment shapes also show self-affine behaviour. Further, scaling of landscape patches show multifractal behaviour and the analysis of these variables yields the characteristic parabolic curves known as multifractal spectra. A novel analytical approach is adopted by using catchments as hydrological cells at various sizes, ranging from first to sixth order, as the unit of measure. This approach is presented as an alternative to the box-counting method as it may be much more representative of hydro-ecological processes at catchment scales. Multifractal spectra are generated for each landscape property and spectral parameters such as the range in α (Holder exponent) values and maximum dimension at α0, (also known as the capacity dimension Dcap), are obtained. Other fractal dimensions (information Dinf and correlation Dcor) are also calculated and compared. The dimensions are connected by the inequality Dcap≥Dinf≥Dcor. Such a relationship strongly suggests that the landscape patches are heterogeneous in nature and that their scaling behaviour can be described as multifractal. The quantitative parameters obtained from the spectra may provide the basis for improved parameterisation of ecological and hydrological models.

  4. A catchment scale water balance model for FIFE

    NASA Technical Reports Server (NTRS)

    Famiglietti, J. S.; Wood, E. F.; Sivapalan, M.; Thongs, D. J.

    1992-01-01

    A catchment scale water balance model is presented and used to predict evaporation from the King's Creek catchment at the First ISLSCP Field Experiment site on the Konza Prairie, Kansas. The model incorporates spatial variability in topography, soils, and precipitation to compute the land surface hydrologic fluxes. A network of 20 rain gages was employed to measure rainfall across the catchment in the summer of 1987. These data were spatially interpolated and used to drive the model during storm periods. During interstorm periods the model was driven by the estimated potential evaporation, which was calculated using net radiation data collected at site 2. Model-computed evaporation is compared to that observed, both at site 2 (grid location 1916-BRS) and the catchment scale, for the simulation period from June 1 to October 9, 1987.

  5. Linking catchment structure to hydrologic function: Implications of catchment topography for patterns of landscape hydrologic connectivity and stream flow dynamics

    NASA Astrophysics Data System (ADS)

    Jencso, K. G.; McGlynn, B. L.; Marshall, L. A.

    2010-12-01

    The relationship between catchment structure (topography and topology), stream network hydrologic connectivity, and runoff response remains poorly understood. Hillslope-riparian-stream (HRS) water table connectivity serves as the hydrologic linkage between a catchment’s uplands and the channel network and facilitates the transmission of water and solutes to streams. While there has been tremendous interest in the concept of hydrological connectivity to characterize catchments, there are relatively few studies that have quantified hydrologic connectivity at the stream network and catchment scales. Here, we examine how catchment topography influenced patterns of stream network HRS connectivity and resultant runoff dynamics across 11 nested headwater catchments in the Tenderfoot Creek Experimental Forest (TCEF), MT. This study extends the empirical findings of Jencso et al. (2009) who found a strong linear relationship (r2 = 0.92) between the upslope accumulated area (UAA) and annual duration of shallow ground water table connectivity observed across 24 HRS transects (146 groundwater recording wells) within the TCEF. We applied this relationship to the entire stream network to quantify the frequency distribution of stream network connectivity through time (as a function of UAA) and ascertain its relationship to catchment-scale runoff dynamics. Each catchment’s estimated connectivity duration curve (CDC) was highly related to its flow duration curve (FDC); albeit the rate of change of runoff with respect to stream network connectedness varied significantly across catchments. To ascertain potential reasons for these differences we compared the slope of each catchment’s CDC-FDC relationship (annual, peak, transition and baseflow periods) in multiple linear models against median values of common terrain indices and land cover-vegetation characteristics. Significant predictors (p<0.05) included the flow path distance to the creek (DFC), the flow path gradient to the

  6. The Roles of Groundwater Flowpaths and Stream Network Expansion in Landscape Connectivity and Resulting Runoff and Solute Dynamics in an Ephemeral Piedmont Catchment

    NASA Astrophysics Data System (ADS)

    Zimmer, M. A.; McGlynn, B. L.

    2014-12-01

    Much catchment hydrology has been conducted in steep, perennial stream watersheds with shallow soil. In contrast, we investigated an ephemeral stream watershed with deep, highly weathered soils, gentle relief, and the dynamic hydro-climatology of the Piedmont region of the United States. We seek to gain new understanding about increasingly recognized challenges in the hydrological sciences, including influences of shallow and deep flowpath connectivity and the role of ephemeral streams in hydrologically connecting distal portions of landscapes. We investigated how overland, shallow soil, and deep subsurface flow across landscape positions and antecedent conditions manifest in observed baseflow and stormflow generation and the dynamics of dissolved organic carbon, electrical conductivity, and a suite of cations and anions. Extensive channel expansion and contraction coupled with spatially and temporally variable shallow and deep groundwater flowpaths led to both clockwise and counter-clockwise hysteresis in the relationship between runoff and solute concentrations as a function of antecedent moisture conditions. This suggests that vertical and horizontal hillslope connectivity to the aquatic system is variable across seasons and storms and influences biogeochemical expression at the watershed scale. Our research in Duke Forest, North Carolina has begun to elucidate the interrelationships between the space-time dynamics of runoff generation processes and observed biogeochemical behavior in this deeply weathered, low relief landscape, to provide new insight into processes widely active but less easily identified and quantified elsewhere.

  7. Moments of catchment storm area

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.; Wang, Q.

    1985-01-01

    The portion of a catchment covered by a stationary rainstorm is modeled by the common area of two overlapping circles. Given that rain occurs within the catchment and conditioned by fixed storm and catchment sizes, the first two moments of the distribution of the common area are derived from purely geometrical considerations. The variance of the wetted fraction is shown to peak when the catchment size is equal to the size of the predominant storm. The conditioning on storm size is removed by assuming a probability distribution based upon the observed fractal behavior of cloud and rainstorm areas.

  8. Hydrological Catchment Similarity Assessment in Geum River Catchments, Korea

    NASA Astrophysics Data System (ADS)

    Ko, Ara; Park, Kisoon; Lee, Hyosang

    2013-04-01

    Similarity measure of catchments is essential for regionalization studies, which provide in depth analysis in hydrological response and flood estimations at ungauged catchments. However, this similarity measure is often biased to the selected catchments and is notclearly explained in hydrological sense. This study applied a type of hydrological similarity distance measure-Flood Estimation Handbook to 25 Geum river catchments, Korea. Three Catchment Characteristics, Area (A)-Annual precipitation (SAAR)-SCS Curve Number (CN), are used in Euclidian distance measures. Furthermore, six index of Flow Duration Curve (ILow:Q275/Q185, IDrought:Q355/Q185, IFlood:Qmax/Q185, IAbundant:Q95/Q185, IFloodDuration:Q10/Q355 and IRiverRegime:Qmax/Qmin) are applied to clustering analysis of SPSS. The catchments' grouping of hydrological similarity measures suggests three groups: H1 (Cheongseong, Gidae, Bukil, Oksan, Seockhwa, Habgang and Sangyeogyo), H2 (Cheongju, Guryong, Ugon, Boksu, Useong and Seokdong) and H3 (Muju, Yangganggyo and YongdamDam). The four catchments (Cheoncheon, Donghyang, DaecheongDam and Indong) are not grouped in this study. The clustering analysis of FDC provides four Groups; CFDC1 (Muju, YongdamDam, Yangganggyo, DaecheongDam, Cheongseong, Gidae, Seokhwa, Bukil, Habgang, Cheongju, Oksan, Yuseong and Guryong), CFDC2 (Cheoncheon, Donghyang, Boksu, Indong, Nonsan, Seokdong, Ugon, Simcheon, Useong and Sangyeogyo), CFDC3 (Songcheon) and CFDC4 (Tanbu). The six catchments (out of seven) of H1 are grouped in CFDC1, while Sangyeogyo is grouped in CFDC2. The four catchments (out of six) of H2 are also grouped in CFDC2, while Cheongju and Guryong are grouped in CFDC1. The catchments of H3 are categorized in CFDC1. The authors examine the results (H1, H2 and H3) of similarity measure based on catchment physical descriptors with results (CFDC1 and CFDC2) of clustering based on catchment hydrological response. The results of hydrological similarity measures are supported by

  9. Groundwater recharge from point to catchment scale

    NASA Astrophysics Data System (ADS)

    Leterme, Bertrand; Di Ciacca, Antoine; Laloy, Eric; Jacques, Diederik

    2016-04-01

    Accurate estimation of groundwater recharge is a challenging task as only a few devices (if any) can measure it directly. In this study, we discuss how groundwater recharge can be calculated at different temporal and spatial scales in the Kleine Nete catchment (Belgium). A small monitoring network is being installed, that is aimed to monitor the changes in dominant processes and to address data availability as one goes from the point to the catchment scale. At the point scale, groundwater recharge is estimated using inversion of soil moisture and/or water potential data and stable isotope concentrations (Koeniger et al. 2015). At the plot scale, it is proposed to monitor the discharge of a small drainage ditch in order to calculate the field groundwater recharge. Electrical conductivity measurements are necessary to separate shallow from deeper groundwater contribution to the ditch discharge (see Di Ciacca et al. poster in session HS8.3.4). At this scale, two or three-dimensional process-based vadose zone models will be used to model subsurface flow. At the catchment scale though, using a mechanistic, process-based model to estimate groundwater recharge is debatable (because of, e.g., the presence of numerous drainage ditches, mixed land use pixels, etc.). We therefore investigate to which extent various types of surrogate models can be used to make the necessary upscaling from the plot scale to the scale of the whole Kleine Nete catchment. Ref. Koeniger P, Gaj M, Beyer M, Himmelsbach T (2015) Review on soil water isotope based groundwater recharge estimations. Hydrological Processes, DOI: 10.1002/hyp.10775

  10. Creating a catchment perspective for river restoration

    NASA Astrophysics Data System (ADS)

    Benda, L.; Miller, D.; Barquín, J.

    2011-03-01

    One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we coupled general principles of hydro-geomorphic processes with computer tools to characterize the fluvial landscape. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to topography, valley morphology, river network structure, and fan and terrace landforms. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  11. 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.

  12. Temporal and Spatial Patterns of Preferential Flow Occurrence in the Shale Hills Catchment: From the Hillslope to the Catchment Scales

    NASA Astrophysics Data System (ADS)

    Liu, H.; Lin, H.

    2013-12-01

    Understanding temporal and spatial patterns of preferential flow (PF) occurrence is important in revealing hillslope and catchment hydrologic and biogeochemical processes. Quantitative assessment of the frequency and control of PF occurrence in the field, however, has been limited, especially at the landscape scale of hillslope and catchment. By using 5.5-years' (2007-2012) real-time soil moisture at 10 sites response to 323 precipitation events, we tested the temporal consistency of PF occurrence at the hillslope scale in the forested Shale Hills Catchment; and by using 25 additional sites with at least 1-year data (2011-2012), we evaluated the spatial patterns of PF occurrence across the catchment. To explore the potential effects of PF occurrence on catchment hydrology, wavelet analysis was performed on the recorded time series of hydrological signals (i.e., precipitation, soil moisture, catchment discharge). Considerable temporal consistence was observed in both the frequency and the main controls of PF occurrence at the hillslope scale, which was attributed largely to the statistical stability of precipitation pattern over the monitoring period and the relatively stable subsurface preferential pathways. Preferential flow tended to occur more often in response to intense rainfall events, and favored the conditions at dry hilltop or wet valley floor sites. When upscaling to the entire catchment, topographic control on the PF occurrence was amplified remarkably, leading to the identification of a subsurface PF network in the catchment. Higher frequency of PF occurrence was observed at the valley floor (average 48%), hilltop (average 46%), and swales/hillslopes near the stream (average 40%), while the hillslopes in the eastern part of the catchment were least likely to experience PF (0-20%). No clear relationship, however, was observed between terrain attributes and PF occurrence, because the initiation and persistency of PF in this catchment was controlled

  13. Dynamic processes in the mountain catchment

    NASA Astrophysics Data System (ADS)

    Trifonova, Tatiana; Arakelian, Sergei

    2015-04-01

    The process of the river cftchment foundation and the mechanisms being in the basis of its development are not clear at present. Principal phenomena determining the dynamics of formation of the river catchment are under our study in this paper for the case of the mountain basin as an example. The methodology of this monitoring includes the space image recognition and computer data processing of the images for the Maliy Caucasus Mountains. Mountain river catchment formation on the slope of the ridge can be considered as a self-organizing staged process of its evolution passing through several non-equilibrium but steady-state conditions. We consider a system of tributaries in the mountain river catchment as a system of cracks, which are formed on the slope of the mountain massif. In other words, the formation of river networks should be the result of development of several processes, among of which the mechanisms of crack development should play a dominant role. The principal results, discussed in the present report, can be formulated as follow. (1) The mountain catchment (litho-watershed) formation takes place under conditions of the confined states of a mountain massif: on the one hand it is bounded by the surface of the slope; but on the other hand, - by a primary cracks density occurrence (as a spatial distribution 3D-crack net). (2) The development in time of the river catchment takes place by several stages. Each stage specifies a definite energetic state of the system in the mountain massif. (3) The overhead river streams arise not only due to surface water, but and namely due to rising of water from underground water horizons over the watercourse cracks penetrating deeply into the underground. (4) The 3D-river catchment structure results in concept in behavior of the unit as an open nonlinear dynamic system with a spatially distributed feedback. The energetic (endogen) processes of formation, rising and bifurcation for cracks are the consequence of relaxation

  14. The catchment based approach using catchment system engineering

    NASA Astrophysics Data System (ADS)

    Jonczyk, Jennine; Quinn, Paul; Barber, Nicholas; Wilkinson, Mark

    2015-04-01

    The catchment based approach (CaBa) has been championed as a potential mechanism for delivery of environmental directives such as the Water Framework Directive in the UK. However, since its launch in 2013, there has been only limited progress towards achieving sustainable, holistic management, with only a few of examples of good practice ( e.g. from the Tyne Rivers trust). Common issues with developing catchment plans over a national scale include limited data and resources to identify issues and source of those issues, how to systematically identify suitable locations for measures or suites of measures that will have the biggest downstream impact and how to overcome barriers for implementing solutions. Catchment System Engineering (CSE) is an interventionist approach to altering the catchment scale runoff regime through the manipulation of hydrological flow pathways throughout the catchment. A significant component of the runoff generation can be managed by targeting hydrological flow pathways at source, such as overland flow, field drain and ditch function, greatly reducing erosive soil losses. Coupled with management of farm nutrients at source, many runoff attenuation features or measures can be co-located to achieve benefits for water quality and biodiversity. A catchment, community-led mitigation measures plan using the CSE approach will be presented from a catchment in Northumberland, Northern England that demonstrate a generic framework for identification of multi-purpose features that slow, store and filter runoff at strategic locations in the landscape. Measures include within-field barriers, edge of field traps and within-ditch measures. Progress on the implementation of measures will be reported alongside potential impacts on the runoff regime at both local and catchment scale and costs.

  15. Vulnerability of European freshwater catchments to climate change.

    PubMed

    Markovic, Danijela; Carrizo, Savrina F; Kärcher, Oskar; Walz, Ariane; David, Jonathan N W

    2017-02-10

    Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers <25% of the most vulnerable catchments. Practical steps need to be taken to ensure the persistence of freshwater biodiversity under climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for

  16. 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

  17. Is the subarctic landscape still a carbon sink? Evidence from a detailed catchment balance

    NASA Astrophysics Data System (ADS)

    Lundin, Erik J.; Klaminder, Jonatan; Giesler, Reiner; Persson, Andreas; Olefeldt, David; Heliasz, Michal; Christensen, Torben R.; Karlsson, Jan

    2016-03-01

    Climate warming raises the question whether high-latitude landscape still function as net carbon (C) sinks. By compiling an integrated C balance for an intensely studied subarctic catchment, we show that this catchment's C balance is not likely to be a strong current sink of C, a commonly held assumption. In fact, it is more plausible (71% probability) that the studied catchment functions as a C source (-11 ± 20 g C m-2 yr-1). Analyses of individual fluxes indicate that soil and aquatic C losses offset C sequestering in other landscape components (e.g., peatlands and aboveground forest biomass). Our results stress the importance of fully integrated catchment C balance estimates and highlight the importance of upland soils and their interaction with the aquatic network for the catchment C balance.

  18. Spatial organisation in hydrological model structure for New Zealand catchments

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary; Woods, Ross; Clark, Martyn

    2013-04-01

    Hydrologists increasingly agree that a single hydrological model structure is unlikely to be suitable for all catchments: instead, models should be selected according to characteristics of the catchment. Our challenge is to determine how to select the most appropriate model structure. This complex question requires that we use observed data to infer dominant runoff generation processes, and translate this process knowledge into model structure choices. We can then ask questions such as: over what scales do recommended model structures change? How much data is needed to select model structure? How can we generalise model structure choices to catchments where data is scarce? In this presentation we address these questions, using the New Zealand landscape as our 'virtual laboratory'. New Zealand is an excellent location to test hypotheses relating to model structure, due to its rich diversity of hydrological landscapes. Landscape types range from temperate rainforest with steep, bedrock gorges, through rolling pasture, to alluvial plains with braided rivers. Our method is to apply diagnostic signatures, which use a range of hydrological data types, to target specific aspects of model structure choice. We bring together results from national hydrometric networks, and in-depth studies in experimental catchments, to explore organisation, similarity and diversity in recommended model structures across the New Zealand landscape. To identify model structures which are consistent with measured data, we use a range of diagnostic signatures tailored to the data types available. At the national scale, networks of rain and flow gauges are used to investigate runoff ratio, recession characteristics and threshold responses to precipitation and soil moisture. At the experimental Mahurangi catchments, dense networks of 13 rain, 27 flow and 36 soil moisture gauges within a 50 km2 area enable us to evaluate small-scale patterns and diversities of model structure. In contrast, the

  19. Deriving N-year discharges in small catchments

    NASA Astrophysics Data System (ADS)

    Ledvinka, Ondrej; Bohac, Milon

    2016-04-01

    Maximum discharges with the return period of 100 years (Q100) belong to basic hydrological data that are derived and provided for any profile of the river network by the Czech Hydrometeorological Institute (CHMI). However, as regards small catchments, the determination of these characteristics is largely subjective and thus it is rather performed by comparing the results of several methods. The first approach is to extrapolate the three parameters of maximum peak discharges (average Qmax, coefficient of variation Cvmax, Q100) from water-gauging stations to selected unobserved profiles (using regression relationships and regularities at the confluence points). For this purpose, the so-called program Budsez is utilized. During this process, the physical-geographical (PG) features, rainfall data and other information about catchments are considered, based on which the parameters of theoretical distributions of N-year discharges are optimized. For smaller catchments the relationships between the 100-year specific runoff q100 and the catchment area and other PG characteristics are used that are determined in a GIS environment with the extension AGPosudek. In this innovative method, besides many other PG characteristics, especially the average value of CN and N-year maximum daily precipitation are taken into account when computing Q100. In the older methodologies, Q100 is based on the average slope of the stream and the average slope of the catchment. The values of Q100 are then corrected according to the percentage of forested areas and the catchment shape. Hydrologists compare the values of Q100 coming from different approaches in a logarithmic graph (q100 against area) for the particular catchment or its analogon. The final value is determined with respect to experience and previously issued values. The remaining N-year discharges are usually assessed through the ratio QN/Q100 from the nearest water-gauging station or the closest profile where these ratios were

  20. Towards Estimating the Nutrient Balance of the Hydrologic Open Air Laboratory (HOAL) Catchment, Lower Austria

    NASA Astrophysics Data System (ADS)

    Exner-Kittridge, Michael; Zessner, Matthias; Broer, Martine; Eder, Alexander; Strauss, Peter; Blöschl, Günter

    2010-05-01

    The fate of nutrients introduced by human activities have significant impacts on both nature and our civilization. Excessive nutrients can contaminate our drinking water as well as promote algae blooms that deplete the surrounding waters of oxygen for aquatic life. It is estimated that agriculture in Austria contributes approximately 60% to the total discharge of nitrogen and 40% to the total discharge of phosphorus. Understanding the specific pathways and sources of nitrogen and phosphorus from agriculture land could greatly improve our ability to mitigate for excessive discharges if the problems can be targeted more precisely. The objective of our research is to determine the complete nitrogen and phosphorous balance within a 66.7 hectare catchment in Lower Austria. The Hydrologic Open Air Laboratory (HOAL) catchment is located in Lower Austria approximately 100 km west of Vienna. The HOAL catchment was established in 2009 through funding by the Austrian Science Foundation to be used for multidisciplinary hydrologic research for understanding water flow and transport processes in catchments. The catchment land cover is characterized as 90% agriculture, 5% impermeable surface, and 3% forest. The predominant soil type is a clayey silt loam and a section of the catchment contain a subsurface tile drainage network that extend approximately 5.5 km. Nitrogen and phosphorus are the two primary nutrients assessed in this study. To accomplish the nutrient balance, the research is divided into three different scales: Field Scale, Subcatchment Scale, and Catchment Scale. The Catchment scale encompasses the entirety of the catchment, the subcatchment scale encompasses a 6.4 hectare area within the catchment that is completely underlain by the tile drainage network, and the field scale studies are performed on several square meter plots within the subcatchment. Each scale attempts to determine different parts of the total nutrient budget. The initial phase of the research

  1. Influence of Rainfall Data Resolution and Catchment Subdivision on Runoff Modelling

    NASA Astrophysics Data System (ADS)

    Puttaraksa Mapiam, Punpim; Chauysuk, Suttiched

    2016-04-01

    Precipitation and catchment characteristics are significant factors for runoff modelling. This study demonstrates the relative benefits offered by the application of alternate rainfall products to several scales of catchment subdivision for simulation of the runoff hydrograph in the upper Ping river basin, northern Thailand. Two point locations at the runoff stations in the upper Ping river basin were selected for model calibration over the period of 2004-2005. Rain gauge and radar rainfall products were specified as inputs to the semi-distributed hydrological URBS model at each runoff station with five catchment subdivision schemes for runoff simulation. Point rainfall from the sparse rain gauge network and estimated radar rainfall at each radar pixel were spatially averaged over each sub-catchment using Thiessen polygons and arithmetic averaging approaches, respectively. Results for using high resolution of radar rainfall input appear that the accuracy of runoff estimates is affected appreciably by a number of sub-catchments, and the accuracy of runoff estimates tends to obviously increase with an increase of the number of sub-catchments. On the other hand, there is no significant improvement with an increasing number of sub-catchments while the coarse resolution of rain gauge rainfall input is used. The comparison on runoff accuracy among different scenarios indicates that the use of radar rainfall together with the largest number of sub-catchments gives the highest accuracy of runoff estimates.

  2. 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

  3. Biogeochemical Dynamics of Zero-Order Arctic Catchments

    NASA Astrophysics Data System (ADS)

    Harms, T.; Godsey, S.; Jones, J.; Risser, R. R.; Rushlow, C. R.

    2013-12-01

    A significant fraction of arctic catchments underlain by permafrost may be drained by linear flowpaths constituting zero-order channels, which are termed water tracks. Hydrology and biogeochemistry of arctic hillslopes are subject to rapid changes caused by thawing permafrost, changing precipitation regime, and altered vegetation patterns. We investigated coupling of hydrologic and biogeochemical cycles at six water tracks that drain to the Kuparuk River to understand the role of zero-order catchments in delivering solutes to stream networks, and better predict how solute fluxes will respond to changing climate. Peak concentrations of organic solutes occurred during snowmelt, and snowmelt-derived water remained in catchments until mid-summer, indicating that changes in snowpack or timing of melt will induce strong changes in delivery of solutes to stream networks. Further, temporal coherence in solute chemistry between water tracks and the Kuparuk river suggests that water tracks are important contributors of solutes to downstream ecosystems. Solute dynamics during storms follow a flush and dilution pattern indicative of source-limited solute transport. However, the relative difference between minimum and maximum concentrations of dissolved organic carbon and ammonium decreased during successive storms, suggesting decreased availability of these solutes as flowpaths deepen throughout the season. Despite these broad patterns, individual water tracks vary significantly in solute concentrations and storm responses, suggesting that site-level characteristics including sources of water contributing to flow, rates of solute uptake, contributing area, and depth of thaw influence the delivery of solutes from arctic hillslopes to stream networks. Hydrologic and biogeochemical signals potentially propagate from these zero-order catchments to stream networks and coasts, and may contribute to observed long-term changes in solute and freshwater fluxes in arctic river networks.

  4. Added-value from a multi-criteria selection of donor catchments in the prediction of continuous streamflow series at ungauged pollution control-sites

    NASA Astrophysics Data System (ADS)

    Drogue, Gilles; Ben Khediri, Wiem; Conan, Céline

    2016-05-01

    We explore the potential of a multi-criteria selection of donor catchments in the prediction of continuous streamflow series by the spatial proximity method. Three criteria have been used: (1) spatial proximity; (2) physical similarity; (3) stream gauging network topology. An extensive assessment of our spatial proximity method variant is made on a 149 catchment-data set located in the Rhine-Meuse catchment. The competitiveness of the method is evaluated against spatial interpolation of catchment model parameters with ordinary kriging. We found that the spatial proximity approach is more efficient than ordinary kriging. When distance to upstream/downstream stream gauge stations is considered as a second order criterion in the selection of donor catchments, an unprecedented level of efficiency is reached for nested catchments. Nevertheless, the spatial proximity method does not take advantage from physical similarity between donor catchments and receiver catchments because catchments that are the most hydrologically similar to each catchment poorly match with the catchments that are the most physically similar to each catchment.

  5. Sediment connectivity evolution on an alpine catchment undergoing glacier retreat

    NASA Astrophysics Data System (ADS)

    Goldin, Beatrice; Rudaz, Benjamin; Bardou, Eric

    2014-05-01

    Climate changes can result in a wide range of variations of natural environment including retreating glaciers. Melting from glaciers will have a significant impact on the sediment transport characteristics of glacierized alpine catchments that can affect downstream channel network. Sediment connectivity assessment, i.e. the degree of connections that controls sediment fluxes between different segments of a landscape, can be useful in order to address management activity on sediment fluxes changes of alpine streams. Through the spatial characterization of the connectivity patterns of a catchment and its potential evolution it is possible to both define sediment transport pathways and estimate different contributions of the sub-catchment as sediment sources. In this study, a topography based index (Cavalli et al., 2013) has been applied to assess spatial sediment connectivity in the Navisence catchment (35 km2), an alpine basin located in the southern Walliser Alps (Switzerland) characterized by a complex glacier system with well-developed lateral moraines on glacier margins already crossed by several lateral channels. Glacier retreat of the main glacial edifice will provide a new connectivity pattern. At present the glacier disconnects lateral slopes from the main talweg: it is expected that its retreat will experience an increased connectivity. In order to study this evolution, two high resolution (2 m) digital terrain models (DTMs) describing respectively the terrain before and after glacier retreat have been analyzed. The current DTM was obtained from high resolution photogrammetry (2 m resolution). The future DTM was derived from application of the sloping local base level (SLBL) routine (Jaboyedoff et al., 2004) on the current glacier system, allowing to remove the ice body by reconstituting a U-shaped polynomial bedrock surface. From this new surface a coherent river network was drawn and slight random noise was added. Finally the river network was burned into

  6. Crossing thresholds: Analysis of hazardous tipping points in alpine catchments

    NASA Astrophysics Data System (ADS)

    Lutzmann, Silke; Sass, Oliver

    2016-04-01

    Steep mountain channels or torrents in small alpine catchments are characterized by high geomorphic activity with sediment dynamics being inherently nonlinear and threshold-mediated. Localized, high intensity rainstorms can drive torrential systems past a tipping point resulting in a sudden onset of hazardous events like (flash-) flooding, heavy bedload transport or debris flows. Such responses exhibit an abrupt switch in the fluvial system's mode (e.g. transport / supply limited). Changes in functional connectivity may persist beyond the tipping point. Torrential hazards cause costly damage in the densely populated Alpine Region. Thus, there is a rising interest in potential effects of climate change on torrential sediment dynamics. Understanding critical conditions close to tipping points is important to reduce uncertainty in predicting sediment fluxes. In this study we aim at (i) establishing threshold precipitation characteristics for the Eastern Alps of Austria. Precipitation is hypothesized to be the main forcing factor of torrential events. (ii) How do thresholds vary in space and time? (iii) The effect of external triggers is strongly mediated by the internal disposition of catchments to respond. Which internal conditions are critical for susceptibility? (iv) Is there a change in magnitude or frequency in the recent past and what can be expected for the future? The 71 km2 catchment of the river Schöttlbach in the East Alpine Region of Styria (Austria) is monitored since a heavy precipitation event resulted in a catastrophic flood in July 2011. Sediment mobilization from slopes as well as within-channel storage and bedload transport are regularly measured using photogrammetric methods and sediment impact sensors. Thus, detailed knowledge exists on magnitude and spatial propagation of sediment waves through the catchment. The associated hydro-meteorological (pre-) conditions can be inferred from a dense station network. Changing bedload transport rates and

  7. What causes similarity in catchments?

    NASA Astrophysics Data System (ADS)

    Savenije, Hubert

    2014-05-01

    One of the biggest issues in hydrology is how to handle the heterogeneity of catchment properties at different scales. But is this really such a big issue? Is this problem not merely the consequence of how we conceptualise and how we model catchments? Is there not far more similarity than we observe. Maybe we are not looking at the right things or at the right scale to see the similarity. The identity of catchments is largely determined by: the landscape, the ecosystem living on the landscape, and the geology, in that order. Soils, which are often seen as a crucial aspect of hydrological behaviour, are far less important, as will be demonstrated. The main determinants of hydrological behaviour are: the landscape composition, the rooting depth and the phenology. These determinants are a consequence of landscape and ecosystem evolution, which, in turn, are the manifestations of entropy production. There are striking similarities between catchments. The different runoff processes from hillslopes are linked and similar in different environments (McDonnell, 2013). Wetlands behave similarly all over the world. The key is to classify landscapes and to link the ecosystems living on them to climate. The ecosystem then is the main controller of hydrological behaviour. Besides phenology, the rooting depth is key in determining runoff behaviour. Both are strongly linked to climate and much less to soil properties. An example is given of how rooting depth is determined by climate, and how rooting depth can be predicted without calibration, providing a strong constraints on the prediction of rainfall partitioning and catchment runoff.

  8. Understanding the relationship between sediment connectivity and spatio-temporal landscape changes in two small catchments

    NASA Astrophysics Data System (ADS)

    Giuseppina Persichillo, Maria; Meisina, Claudia; Cavalli, Marco; Crema, Stefano; Bordoni, Massimiliano

    2016-04-01

    The degree of linkage between the sediments sources and downstream areas (i.e., sediment connectivity) is one of the most important properties controlling landscape evolution. Many factors have been found to affect sediment connectivity, especially at the catchment scale. In particular, the degree of linkage between different areas within a catchment depends largely on the morphological complexity of the catchment (relief, terrain roughness, stream network density and catchment shape) and the combined effects of vegetation, such as land use changes and land abandonment. Moreover, the analysis of the spatial distribution of sediment connectivity and its temporal evolution can be also useful for the characterization of sediment source areas. Specifically, these areas represent sites of instability and their connectivity influences the probability that a local on-site effect could propagate within a multiple-events feedback system. Within this framework, the aim of this study is to apply a geomorphometric approach to analyze the linkage between landscape complexity and the sediment connectivity at the catchment scale. Moreover, to assess sediment delivery, the index of connectivity (IC) proposed by Cavalli et al. (2013) was used to evaluate the potential connection of sediment source areas with the main channel network. To better understand the relationship between morphological complexity of the catchment's landscape and the sediment spatial distribution and mobilization, two catchments with different size and geomorphological and land use characteristics were analysed: the Rio Frate and Versa catchments (Oltrepo Pavese, Southern Lombardy, Italy). Several shallow landslides, which represents the main sediment source area type in the catchments, were triggered especially in the period from 2009 to 2013. Moreover, relevant modification of land use and drainage system during last decades, especially related to land abandonment, have conditioned the sediment connectivity

  9. Coevolution of volcanic catchments in Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, Takeo; Troch, Peter A.

    2016-03-01

    Present-day landscapes have evolved over time through interactions between the prevailing climates and geological settings. Understanding the linkage between spatial patterns of landforms, soils, and vegetation in landscapes and their hydrological response is critical to make quantitative predictions in ungaged basins. Catchment coevolution is a theoretical framework that seeks to formulate hypotheses about the mechanisms and conditions that determine the historical development of catchments and how such evolution affects their hydrological response. In this study, we selected 14 volcanic catchments of different ages (from 0.225 to 82.2 Ma) in Japan. We derived indices of landscape properties (drainage density and slope-area relationship) as well as hydrological response (annual water balance, baseflow index, and flow-duration curves) and examined their relation with catchment age and climate (through the aridity index). We found a significant correlation between drainage density and baseflow index with age, but not with climate. The intra-annual flow variability was also significantly related to catchments age. Younger catchments tended to have lower peak flows and higher low flows, while older catchments exhibited more flashy runoff. The decrease in baseflow with catchment age is consistent with the existing hypothesis that in volcanic landscapes the major flow pathways change over time from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in a set of similar, but younger volcanic catchments in the Oregon Cascades, in which drainage density increased with age. In that case, older catchments were thought to show more landscape incision due to increasing near-surface lateral flow paths. Our results suggests two competing hypotheses on the evolution of drainage density in mature catchments. One is that as catchments continue to age, the hydrologically active channels retreat

  10. Mapping storm velocity over catchments: Distribution and scale dependence for flash flood-inducing storms.

    NASA Astrophysics Data System (ADS)

    Nikolopoulos, E. I.; Zoccatelli, D.; Anagnostou, E. N.

    2012-04-01

    The concept of catchment-scale storm velocity permits examination of storm motion and velocity from the perspective of a distance metric imposed by the drainage network structure of a catchment. This paper aims to examine the distribution and scale-dependency of catchment scale storm velocity values for major flash flood-inducing storms. Eight extreme flash flood-inducing storms occurred in Europe in the period 1999 to 2008 are examined. Analyses are carried out for a set of basins that range in area from 7 to 982 km2. It is shown that the distribution of catchment-scale storm velocity depends on basin-averaged rain rate and catchment size. Hourly velocity values corresponding to maximal rain rates during the flood producing period exhibit a non linear dependence on basin scale and may attain values as high as 2 m s-1. Integration of velocity over the catchment response time leads to a reduction of maximal velocities. Response-time integrated maximal storm velocity shows a peak for catchment scales in the range of 20-100 km2, with values up to 1 m s-1.

  11. The application of GEOtop for catchment scale hydrology in Ireland

    NASA Astrophysics Data System (ADS)

    Lewis, C.; Xu, X.; Albertson, J.; Kiely, G.

    2009-04-01

    GEOtop represents the new generation of distributed hydrological model driven by geospatial data (e.g. topography, soils, vegetation, land cover). It estimates rainfall-runoff, evapotranspiration and provides spatially distributed outputs as well as routing water and sediment flows through stream and river networks. The original version of GEOtop designed in Italy, includes a rigorous treatment of the core hydrological processes (e.g. unsaturated and saturated flow and transport, surface energy balances, and streamflow generation/routing). Recently GEOtop was extended to include treatment of shallow landslides. The GEOtop model is built on an open-source programming framework, which makes it well suited for adaptation and extension. GEOtop has been run very successfully in a number of alpine catchments (such as Brenta) but has not been used on Irish catchments before. The cell size used for the spatially distributed inputs varies from catchment to catchment. In smaller catchments (less than 2000ha) 50 by 50m cells have been used and 200 by 200 for larger catchments. Smaller cell sizes have been found to significantly increase the computational time so a larger cell size is used providing it does not significantly affect the performance of the model. Digital elevation model, drainage direction, landuse and soil type maps are the minimum spatial requirements with precipitation, radiation, temperature, atmospheric pressure and wind speed been the minimum meteorological requirements for a successful run. The soil type maps must also contain information regarding texture and hydraulic conductivity. The first trial of GEOtop in Ireland was on a small 1524 ha catchment in the south of Ireland. The catchment ranges from 50 to just over 200m, the land use is predominately agricultural grassland and it receives on average 1400mm of rain per year. Within this catchment there is a meteorological tower which provides the meteorological inputs, soil moisture is also recorded at

  12. A water and sediment budget for a Mediterranean mountainous catchment (Southern Pyrenees)

    NASA Astrophysics Data System (ADS)

    Tuset, Jordi; Vericat, Damià; Batalla, Ramon J.

    2016-04-01

    Sediment transport in Mediterranean mountainous catchments is highly variable influenced principally by sediment availability, which in turn is controlled by the temporal and spatial variability of rainfall, runoff and land uses. In this paper we present the water and sediment budget of the Ribera Salada, a Mediterranean forest catchment located in the Catalan Pre-Pyrenees (NE Iberian Peninsula). The river drains an area of 224 km2. The data acquisition design is composed by five nested experimental sub-catchments. Each monitoring station registers discharge and suspended sediment transport continuously. Here we present the data obtained between 2012 and 2013, two contrasted hydrological years. These data allows to analyse the contribution of each sub-catchment to the total water and suspended sediment yield of the catchment at multiple temporal scales. Annual water yield in the catchment outlet varied between 15 and 31 hm3 y-1. Maximum peak flow in the outlet of the basin was 60.9 m3 s-1; equivalent to a specific discharge of 0.28 m3 s-1 km2. Results indicate that, hydrologically, the catchment can divided in two areas with contrasted regimes. The upper part of catchment is the wettest zone, where the water yield of each sub-catchment is in directly and positive correlated to its area. In contrast, the bottom of the valley has an ephemeral hydrological regime that only supplies water during important rainfall events. Annual suspended sediment load at the catchment outlet oscillated between 615 and 3415 t y-1, with an average value of 2015 t y-1 (i.e. 9.3 t km-2 y-1). In contrast to the water yield, most of the suspended sediment load (i.e. 80%) is supplied from the driest part of the catchment where sediment availability is greater and there is a greater connectivity between sediment sources and the channel network. The humid part of the catchment only yielded the 20% of the sediment load, where, as in the case of the water yield, sediment yield is directly and

  13. Geomorphometric assessment of spatial sediment connectivity in small Alpine catchments

    NASA Astrophysics Data System (ADS)

    Cavalli, Marco; Trevisani, Sebastiano; Comiti, Francesco; Marchi, Lorenzo

    2013-04-01

    Complex and rugged topography induces large variations in erosion and sediment delivery in the headwaters of alpine catchments. An effective connection of hillslopes with the channel network results in highly efficient sediment transfer processes, such as debris flows. In contrast, morphological conditions producing decoupling of hillslopes from channels (e.g. glacial cirques) may exclude large areas of the catchment from sediment delivery to its lower parts. Moreover, an efficient connection between hillslopes and channel network does not always ensure an effective downstream transfer of sediment. Low-slope channel reaches (e.g. in hanging valleys) cause sediment deposition, which often results in changes of the sediment transport processes, typically from debris flow to streamflow with low bedload and suspended load rates. The availability of high-resolution digital terrain models, such as those derived from aerial LiDAR, improves our capability to quantify the topographic controls on sediment connectivity. A geomorphometric index, based on the approach by Borselli et al. (2008), was developed and applied to assess spatial sediment connectivity in two small catchments of the Italian Alps featuring contrasting morphological characteristics. The results of the geomorphometric analysis were checked against field evidences, showing good performance and thus potential usefulness of the index.

  14. CAOS: the nested catchment soil-vegetation-atmosphere observation platform

    NASA Astrophysics Data System (ADS)

    Weiler, Markus; Blume, Theresa

    2016-04-01

    Most catchment based observations linking hydrometeorology, ecohydrology, soil hydrology and hydrogeology are typically not integrated with each other and lack a consistent and appropriate spatial-temporal resolution. Within the research network CAOS (Catchments As Organized Systems), we have initiated and developed a novel and integrated observation platform in several catchments in Luxembourg. In 20 nested catchments covering three distinct geologies the subscale processes at the bedrock-soil-vegetation-atmosphere interface are being monitored at 46 sensor cluster locations. Each sensor cluster is designed to observe a variety of different fluxes and state variables above and below ground, in the saturated and unsaturated zone. The numbers of sensors are chosen to capture the spatial variability as well the average dynamics. At each of these sensor clusters three soil moisture profiles with sensors at different depths, four soil temperature profiles as well as matric potential, air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels are measured continuously. In addition, most sensors also measure temperature (water, soil, atmosphere) and electrical conductivity. This setup allows us to determine the local water and energy balance at each of these sites. The discharge gauging sites in the nested catchments are also equipped with automatic water samplers to monitor water quality and water stable isotopes continuously. Furthermore, water temperature and electrical conductivity observations are extended to over 120 locations distributed across the entire stream network to capture the energy exchange between the groundwater, stream water and atmosphere. The measurements at the sensor clusters are complemented by hydrometeorological observations (rain radar, network of distrometers and dense network of precipitation gauges) and linked with high resolution meteorological models. In this

  15. How tritium illuminates catchment structure

    NASA Astrophysics Data System (ADS)

    Stewart, M.; Morgenstern, U.; McDonnell, J.

    2012-04-01

    Streams contain water which has taken widely-varying times to pass through catchments, and the distribution of ages is likely to change with the flow. Part of the water has 'runoff' straight to the stream with little delay, other parts are more delayed and some has taken years (in some cases decades) to traverse the deeper regolith or bedrock of the catchment. This work aims to establish the significance of the last component, which is important because it can cause catchments to have long memories of contaminant inputs (e.g. nitrate). Results of tritium studies on streams world-wide were accessed from the scientific literature. Most of the studies assumed that there were just two age-components present in the streams (i.e. young and old). The mean ages and proportions of the components were found by fitting simulations to tritium data. It was found that the old component in streams was substantial (average was 50% of the annual runoff) and had considerable age (average mean age was 10 years) (Stewart et al., 2010). Use of oxygen-18 or chloride variations to estimate streamflow mean age usually does not reveal the age or size of this old component, because these methods cannot detect water older than about four years. Consequently, the use of tritium has shown that substantial parts of streamflow in headwater catchments are older than expected, and that deep groundwater plays an active and sometimes even a dominant role in runoff generation. Difficulties with interpretation of tritium in streams in recent years due to interference from tritium due to nuclear weapons testing are becoming less serious, because very accurate tritium measurements can be made and there is now little bomb-tritium remaining in the atmosphere. Mean ages can often be estimated from single tritium measurements in the Southern Hemisphere, because there was much less bomb-tritium in the atmosphere. This may also be possible for some locations in the Northern Hemisphere. Age determination on

  16. A physically-based Distributed Hydrologic Model for Tropical Catchments

    NASA Astrophysics Data System (ADS)

    Abebe, N. A.; Ogden, F. L.

    2010-12-01

    Hydrological models are mathematical formulations intended to represent observed hydrological processes in a watershed. Simulated watersheds in turn vary in their nature based on their geographic location, altitude, climatic variables and geology and soil formation. Due to these variations, available hydrologic models vary in process formulation, spatial and temporal resolution and data demand. Many tropical watersheds are characterized by extensive and persistent biological activity and a large amount of rain. The Agua Salud catchments located within the Panama Canal Watershed, Panama, are such catchments identified by steep rolling topography, deep soils derived from weathered bedrock, and limited exposed bedrock. Tropical soils are highly affected by soil cracks, decayed tree roots and earthworm burrows forming a network of preferential flow paths that drain to a perched water table, which forms at a depth where the vertical hydraulic conductivity is significantly reduced near the bottom of the bioturbation layer. We have developed a physics-based, spatially distributed, multi-layered hydrologic model to simulate the dominant processes in these tropical watersheds. The model incorporates the major flow processes including overland flow, channel flow, matrix and non-Richards film flow infiltration, lateral downslope saturated matrix and non-Darcian pipe flow in the bioturbation layer, and deep saturated groundwater flow. Emphasis is given to the modeling of subsurface unsaturated zone soil moisture dynamics and the saturated preferential lateral flow from the network of macrospores. Preliminary results indicate that the model has the capability to simulate the complex hydrological processes in the catchment and will be a useful tool in the ongoing comprehensive ecohydrological studies in tropical catchments, and help improve our understanding of the hydrological effects of deforestation and aforestation.

  17. Catchment classification by means of hydrological models

    NASA Astrophysics Data System (ADS)

    Hellebrand, Hugo; Ley, Rita; Casper, Markus

    2013-04-01

    An important hydrological objective is catchment classification that will serve as a basis for the regionalisation of discharge parameters or model parameters. The main task of this study is the development and assessment of two classification approaches with respect to their efficiency in catchment classification. The study area in western Germany comprises about 80 catchments that range in size from 8 km2 up to 1500 km2, covering a wide range of geological substrata, soils, landscapes and mean annual precipitation. In a first approach Self Organising Maps (SOMs) use discharge characteristics or catchment characteristics to classify the catchments of the study area. Next, a reference hydrological model calibrates the catchments of the study area and tests the possibilities of parameter transfer. Compared to the transfer of parameters outside a class, for most catchments the model performance improves when parameters within a class are transferred. Thus, it should be possible to distinguish catchment classes by means of a hydrological model. The classification results of the SOM are compared to the classification results of the reference hydrological model in order to determine the latter validity. The second approach builds on the first approach in such a way that it uses the Superflex Modelling Framework instead of only one reference model. Within this framework multiple conceptual model structures can be calibrated and adapted. Input data for each calibration of a catchment are hourly time series of runoff, precipitation and evaporation for at least eight years. The calibration of multiple models for each catchment and their comparison allows for the assessment of the influence of different model structures on model performance. Learning loops analyse model performance and adapt model structures accordingly with a view to performance improvement. The result of the modelling exercise is a best performing model structure for each catchment that serves as a basis

  18. Hydrologic connectivity between landscapes and streams: Transferring reach- and plot-scale understanding to the catchment scale

    USGS Publications Warehouse

    Jencso, K.G.; McGlynn, B.L.; Gooseff, M.N.; Wondzell, S.M.; Bencala, K.E.; Marshall, L.A.

    2009-01-01

    The relationship between catchment structure and runoff characteristics is poorly understood. In steep headwater catchments with shallow soils the accumulation of hillslope area (upslope accumulated area (UAA)) is a hypothesized first-order control on the distribution of soil water and groundwater. Hillslope-riparian water table connectivity represents the linkage between the dominant catchment landscape elements (hillslopes and riparian zones) and the channel network. Hydrologic connectivity between hillslope-riparian-stream (HRS) landscape elements is heterogeneous in space and often temporally transient. We sought to test the relationship between UAA and the existence and longevity of HRS shallow groundwater connectivity. We quantified water table connectivity based on 84 recording wells distributed across 24 HRS transects within the Tenderfoot Creek Experimental Forest (U.S. Forest Service), northern Rocky Mountains, Montana. Correlations were observed between the longevity of HRS water table connectivity and the size of each transect's UAA (r2 = 0.91). We applied this relationship to the entire stream network to quantify landscape-scale connectivity through time and ascertain its relationship to catchment-scale runoff dynamics. We found that the shape of the estimated annual landscape connectivity duration curve was highly related to the catchment flow duration curve (r2 = 0.95). This research suggests internal catchment landscape structure (topography and topology) as a first-order control on runoff source area and whole catchment response characteristics. Copyright 2009 by the American Geophysical Union.

  19. Map correlation method: Selection of a reference streamgage to estimate daily streamflow at ungaged catchments.

    USGS Publications Warehouse

    Archfield, Stacey A.; Vogel, Richard M.

    2010-01-01

    Daily streamflow time series are critical to a very broad range of hydrologic problems. Whereas daily streamflow time series are readily obtained from gaged catchments, streamflow information is commonly needed at catchments for which no measured streamflow information exists. At ungaged catchments, methods to estimate daily streamflow time series typically require the use of a reference streamgage, which transfers properties of the streamflow time series at a reference streamgage to the ungaged catchment. Therefore, the selection of a reference streamgage is one of the central challenges associated with estimation of daily streamflow at ungaged basins. The reference streamgage is typically selected by choosing the nearest streamgage; however, this paper shows that selection of the nearest streamgage does not provide a consistent selection criterion. We introduce a new method, termed the map-correlation method, which selects the reference streamgage whose daily streamflows are most correlated with an ungaged catchment. When applied to the estimation of daily streamflow at 28 streamgages across southern New England, daily streamflows estimated by a reference streamgage selected using the map-correlation method generally provides improved estimates of daily streamflow time series over streamflows estimated by the selection and use of the nearest streamgage. The map correlation method could have potential for many other applications including identifying redundancy and uniqueness in a streamgage network, calibration of rainfall runoff models at ungaged sites, as well as for use in catchment classification.

  20. Storage as a Metric of Catchment Comparison

    USGS Publications Warehouse

    McNamara, J.P.; Tetzlaff, D.; Bishop, K.; Soulsby, C.; Seyfried, M.; Peters, N.E.; Aulenbach, Brent T.; Hooper, R.

    2011-01-01

    The volume of water stored within a catchment, and its partitioning among groundwater, soil moisture, snowpack, vegetation, and surface water are the variables that ultimately characterize the state of the hydrologic system. Accordingly, storage may provide useful metrics for catchment comparison. Unfortunately, measuring and predicting the amount of water present in a catchment is seldom done; tracking the dynamics of these stores is even rarer. Storage moderates fluxes and exerts critical controls on a wide range of hydrologic and biologic functions of a catchment. While understanding runoff generation and other processes by which catchments release water will always be central to hydrologic science, it is equally essential to understand how catchments retain water. We have initiated a catchment comparison exercise to begin assessing the value of viewing catchments from the storage perspective. The exercise is based on existing data from five watersheds, no common experimental design, and no integrated modelling efforts. Rather, storage was estimated independently for each site. This briefing presents some initial results of the exercise, poses questions about the definitions and importance of storage and the storage perspective, and suggests future directions for ongoing activities. ?? 2011 John Wiley & Sons, Ltd.

  1. Trend analysis of nutrient loadings in the South Saskatchewan River catchment

    NASA Astrophysics Data System (ADS)

    Morales-Marin, L. A.; Chun, K. P.; Wheater, H. S.; Lindenschmidt, K. E.

    2015-12-01

    Nutrient loadings in river catchments have increased in the past years as a consequence of rapid expansion of agricultural areas, new urban developments and industries, and population growth. Nutrient enrichment of water bodies has intensified eutrophication conditions that degrade water quality and ecosystem health. In large-scale catchments, the assessment of temporal and spatial variability of nutrient loads imply challenges due to climate, land use and geology heterogeneity, and to anthropogenic changes. In this study we carried out a trend analysis of total phosphorus and total nitrogen loads in the South Saskatchewan River (SSR) catchment. This catchment is located in the Canadian Prairie Provinces of Alberta and Saskatchewan. The eastern and central areas of the catchment consist mostly of croplands, pasture lands and livestock farms, whereas the western parts are located on the Rocky Mountains that are the source of most of the catchment's streamflows. The trend analysis was performed applying a novel approach to analyse nutrient time series recorded at long-term water quality stations along the main stems of the SSR river network. Since water quality is taken infrequently, in the proposed approach the time series were complemented using regression analysis methods based on streamflow data recorded at the nearest gauge stations. The time series were subsequently pre-whitened in order to remove the autocorrelation, and then subjected to non-parametric statistical test to detect trends. Seasonal analysis of trends at each of the water quality stations were performed in order to determine the relationships between annual flow regimes and nutrient loads in the catchment, in particular, the influence of the high spring runoff on nutrient export. Decadal analysis was also performed to determine the long-tern relationships of nutrients with anthropogenic changes in the catchment. In particular, the capacity of reservoirs to trap nutrients and the effects of the

  2. Runoff generation in a Mediterranean semi-arid landscape: Thresholds, scale, rainfall and catchment characteristics

    NASA Astrophysics Data System (ADS)

    Ries, Fabian; Schmidt, Sebastian; Sauter, Martin; Lange, Jens

    2016-04-01

    Surface runoff acts as an integrated response of catchment characteristics and hydrological processes. In the Eastern Mediterranean region, a lack of runoff data has hindered a better understanding of runoff generation processes on the catchment scale, despite the importance of surface runoff as a water resource or flood hazard. Our main aim was to identify and explain differences in catchment runoff reactions across a variety of scales. Over a period of five years, we observed runoff in ephemeral streams of seven watersheds with sizes between 3 and 129 km2. Landuse and surface cover types (share of vegetation, bare soil and rock outcrops) were derived from aerial images by objective classification techniques. Using data from a dense rainfall network we analysed the effects of scale, catchment properties and aridity on runoff generation. Thereby we extracted rainfall and corresponding runoff events from our time-series to calculate event based rainfall characteristics and catchment runoff coefficients. Soil moisture observations provided additional information on antecedent moisture conditions, infiltration characteristics and the evolution of saturated areas. In contrast to the prevailing opinion that the proportion of Hortonian overland flow increases with aridity, we found that in our area the largest share (> 95 %) of runoff is generated by saturation excess overland flow in response to long lasting, rainfall events of high amount. This was supported by a strong correlation between event runoff and precipitation totals. Similar rainfall thresholds (50 mm) for runoff generation were observed in all investigated catchments. No scale effects on runoff coefficients were found; instead we identified up to three-fold runoff coefficients in catchments with larger extension of arid areas, higher percentage of rock outcrops and urbanization. Comparing two headwater catchments with noticeable differences in extent of olive orchards, no difference in runoff generation was

  3. Restoring Landform Geodiversity in Modified Rivers and Catchments

    NASA Astrophysics Data System (ADS)

    Smith, Ben; Clifford, Nicholas

    2014-05-01

    also undertaken to show landform position within catchments and the wider river network. We conclude that river restoration could play an important role in the assessment and improvement of geodiversity within heavily-modified European catchments

  4. Catchment Very-High Frequency Hydrochemistry: the Critex Chemical House

    NASA Astrophysics Data System (ADS)

    Floury, P.; Gaillardet, J.; Tallec, G.; Blanchouin, A.; Ansart, P.

    2015-12-01

    Exploring the variations of river quality at very high frequency is still a big challenge that has fundamental implications both for understanding catchment ecosystems and for water quality monitoring. Within the French Critical Zone program CRITEX, we have proposed to develop a prototype called "Chemical House", applying the "lab on field" concept to one of the stream of the Orgeval Critical Zone Observatory. The Orgeval catchment (45 km2) is part of the Critical Zone RBV ("Réseau des bassins versants") network. It is a typical temperate agricultural catchment that has been intensively monitored for the last 50 years for hydrology and nutrient chemistry. Agricultural inputs and land use are also finely monitored making Orgeval an ideal basin to test the response of the Critical Zone to agricultural forcing. Geology consists of a typical sedimentary basin of Cenozoic age with horizontal layers of limestones, silcrete and marls, covered by a thin loamy layer. Two main aquifers are present within the catchment: the Brie and the Champigny aquifers. Mean runoff is 780 mm/yr. The Chemical House is a fully automated lab and installed directly along the river, which performs measurement of all major dissolved elements such as Na, Cl, Mg, Ca, NO3, SO4 and K every half hour. It also records all physical parameters (Temperature, pH, conductivity, O2 dissolved, Turbidity) of the water every minute. Orgeval Chemical House started to measure river chemistry on June 12, 2015 and has successfully now recorded several months of data. We will present the architecture of the Chemical House and the first reproducibility and accuracy tests made during the summer drought 2015 period. Preliminary results show that the chemical house is recoding significant nychtemeral (day/night) cycles for each element. We also observe that each element has its own behaviour along a day. First results open great prospects.

  5. Creating a catchment scale perspective for river restoration

    NASA Astrophysics Data System (ADS)

    Benda, L.; Miller, D.; Barquín, J.

    2011-09-01

    One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we used computer tools to examine the spatial patterns of fluvial landscapes that are associated with five domains of hydro-geomorphic processes and landforms. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to hillslope and valley topography, river network structure, and channel elevation profiles. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  6. Dominant controls on catchment hydrological functions: what can we learn from biological and isotopic tracers?

    NASA Astrophysics Data System (ADS)

    Pfister, L.; Klaus, J.; Wetzel, C. E.; Stewart, M. K.; McDonnell, J.; Martinez Carreras, N.

    2014-12-01

    One emerging and important control on catchment hydrological functions of water storage, mixing and release is bedrock geology. Until today, catchment-based work has been limited by small ranges of rock types in adjacent basins. Moreover, conventional hydrological tracer approaches suffer from limitations inherent to the large storages related to certain bedrock types (e.g. the damping of stable isotope tracer signatures in deep storage catchments and obliteration of output signals at larger spatial scales). Here, we show how a multi-tracer approach, based on terrestrial diatoms and different stable and radioactive isotopic tracers can help refining our understanding of the dominant controls on catchment hydrological functions, especially the role of bedrock geology. We present new data and results from a nested catchment set-up, located in the Alzette River basin in Luxembourg (Europe). These 16 catchments (with sizes ranging from 0.47 to 285 km2) are characterized by clean and mixed assemblages of geology and land use. We have monitored these systems since 2002, including meteorological variables (precipitation, air temperature, etc.), as well as 15 minute discharge. Additional parameters have been monitored bi-weekly and at the event time scale, including geochemical and isotopic (3H, D, 18O) tracers, as well as terrestrial diatom communities in streamwater. Our results show that water balance derived dynamic storage significantly differs across the 16 catchments and scales. Catchment mixing potential inferred from standard deviations in stream baseflow ∂D (as a proxy for the damping of isotopic signatures in precipitation), as well as tritium-derived baseflow transit times, both exhibit a significant spatial variability, but strong correlation to bedrock pemeability. Terrestrial diatom assemblages in streamwater, as a proxy for rapid flow pathway connectedness to the stream network, are highly variable across the study catchments but also show strong

  7. 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

    used to compare the runoff of 11 small catchments with ephemeral streams (0,1-0,6 km2) with the given uncertainty at both the event and the annual scale (Crabit et al., in Hydrological Processes 25 (18), 2011). The results indicate significant variability between the catchment's responses. This variability allows for classification in spite of all the uncertainty associated with runoff estimation. This study highlights the potential of using a network of poorly gauged catchments. From almost no catchment understanding the proposed methodology allows to compare poorly gauged catchments and highlights similarity/dissimilarity between catchment responses.

  8. Hydrological characterisation of pesticide loads using hydrograph separation at different scales in a German catchment

    NASA Astrophysics Data System (ADS)

    Müller, K.; Deurer, M.; Hartmann, H.; Bach, M.; Spiteller, M.; Frede, H.-G.

    2003-03-01

    Pesticide pollution of surface waters was studied in a 49.7 km 2 catchment in Germany. The loads were differentiated into point source (PSP) and non-point source pollution (NPSP). The contribution of runoff, interflow, groundwater, drainage and spray drift to river contamination was defined as NPSP. Pesticides discharged into the river via wastewater treatment plants and sewer overflows were considered as PSP. Hydrology and pesticide loads were studied on the scale of the entire catchment and in two sub-catchments not influenced by PSP. River discharges and concentrations of 19 pesticides were measured at four locations over 447 days. The total load detected in the entire catchment amounted to 3249 g active ingredient (a.i.). The stream flow data were separated into base and direct flow applying a non-linear reservoir separation algorithm. Single rainfall events leading to runoff and interflow dominated NPSP in the sub-catchments. For the sub-catchment Rossberg 87% and for Leidenhofen 71% of the pesticide load could be attributed to direct flow. This corresponded to 14 and 34% time of peak flow events for Rossberg and Leidenhofen, respectively. For the entire catchment only 15% of the NPSP was transported with direct flow with 49% attributed to base flow. The difference between the entire and the sub-catchment contribution was attributed to dilution, hysteresis and merging effects. Applying a digital recursive filter technique for hydrograph separation confirmed the results of the non-linear reservoir separation algorithm. The impact of the hydrograph separation technique on the hydrological characterisation of pesticide loads was insignificant. The results emphasise the dynamic nature of pesticide transport and its complex interaction between size and position of source areas along a stream flow network. The measured loads in the sub-catchments were scaled up to the entire catchment as an estimate for the total NPSP. The fraction of the area treated with a

  9. Catchment-scale biogeography of riverine bacterioplankton.

    PubMed

    Read, Daniel S; Gweon, Hyun S; Bowes, Michael J; Newbold, Lindsay K; Field, Dawn; Bailey, Mark J; Griffiths, Robert I

    2015-02-01

    Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physico-chemical status of the river.

  10. Catchment-scale biogeography of riverine bacterioplankton

    PubMed Central

    Read, Daniel S; Gweon, Hyun S; Bowes, Michael J; Newbold, Lindsay K; Field, Dawn; Bailey, Mark J; Griffiths, Robert I

    2015-01-01

    Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physico-chemical status of the river. PMID:25238398

  11. Instrumenting Wildlife Water Developments to Measure Precipitation and Estimate Runoff in Remote Catchments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Nevada, available data on precipitation and runoff in remote catchments are extremely limited. The National Weather Service’s Cooperative Observer Network (COOP) includes 178 weather stations, most of which collect precipitation data and qualitative weather observations. Most of these stations ar...

  12. Using Wildlife Water Developments to Measure Precipitation and Estimate Runoff in Remote Catchments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Nevada, available data on precipitation and runoff in remote catchments is extremely limited. The National Weather Service’s Cooperative Observer Network (COOP) includes 178 weather stations, most of which collect precipitation data and qualitative weather observations. Most of these stations a...

  13. Morphometric properties of the trans-Himalayan river catchments: Clues towards a relative chronology of orogen-wide drainage integration

    NASA Astrophysics Data System (ADS)

    Ghosh, Parthasarathi; Sinha, Sayan; Misra, Arindam

    2015-03-01

    The geomorphological evolution of the Himalayan mountain belt both in terms of crustal deformation and concomitant erosion by surface processes has been suggested to have a profound influence on a number of earth system processes and has been extensively researched through a number of different techniques. The huge catchments of the trans-Himalayan rivers are the product of long-term fluvial erosion of the landscape. This work attempts to understand their evolution through a study of drainage network, morphology, and internal organization of the smaller watersheds nested within each catchment. Using morphometric techniques applied to an orogen-wide digital elevation data grid, we characterized the drainage network structure and catchment of all the 18 trans-Himalayan rivers situated between the exits of the Indus and Brahmaputra rivers and constructed rectangular approximations of the catchment geometries. With the help of catchment dimensions measured transverse and parallel to the strike of the orogen, and by analyzing the dimension and spatial dispositions of the rectangular approximations, we demonstrate that the trans-Himalayan catchment shapes cannot be explained only as a product of the headward enlargement of drainage networks on a topographic slope, or orogenic taper. Within individual catchments we identified the existence of drainage components (watersheds) that are organized in a systematic manner with respect to the first-order physiographic features of the Himalayas, formed at different periods of geological time. Each of them shows distinct morphometric characteristics that are indicative of differences in processes and / or time scale involved in their formation. The hypsometric properties of the watersheds occupying the upper part of the catchments suggest that they are the remnants of pre-orogenic drainage that became confined to the leeward side of the Himalayas before the advent of monsoon circulation. The shape and organization of the

  14. Does the simple dynamical systems approach provide useful information about catchment hydrological functioning in a Mediterranean context? Application to the Ardèche catchment (France)

    NASA Astrophysics Data System (ADS)

    Adamovic, M.; Braud, I.; Branger, F.; Kirchner, J. W.

    2014-09-01

    This study explores how catchment heterogeneity and variability can be summarized in simplified models, representing the dominant hydrological processes. It focuses on Mediterranean catchments, characterized by heterogeneous geology, pedology, and land use, as well as steep topography and a rainfall regime in which summer droughts contrast with high-rainfall periods in autumn. The Ardèche catchment (south-east France), typical of this environment, is chosen to explore the following questions: (1) can such a Mediterranean catchment be adequately characterized by simple dynamical systems approach and what are the limits of the method under such conditions? (2) What information about dominant predictors of hydrological variability can be retrieved from this analysis in such catchments? In this work we apply the data-driven approach of Kirchner (WRR, 2009) to estimate discharge sensitivity functions that summarize the behavior of four sub-catchments of the Ardèche, using non-vegetation periods (November-March) from 9 years of data (2000-2008) from operational networks. The relevance of the inferred sensitivity function is assessed through hydrograph simulations, and through estimating precipitation rates from discharge fluctuations. We find that the discharge-sensitivity function is downward-curving in double-logarithmic space, thus allowing further simulation of discharge and non-divergence of the model, only during non-vegetation periods. The analysis is complemented by a Monte-Carlo sensitivity analysis showing how the parameters summarizing the discharge sensitivity function impact the simulated hydrographs. The resulting discharge simulation results are good for granite catchments, found to be predominantly characterized by saturation excess runoff and sub-surface flow processes. The simple dynamical system hypothesis works especially well in wet conditions (peaks and recessions are well modeled). On the other hand, poor model performance is associated with

  15. Improved understanding and prediction of the hydrologic response of highly urbanized catchments through development of the Illinois Urban Hydrologic Model

    NASA Astrophysics Data System (ADS)

    Cantone, Joshua; Schmidt, Arthur

    2011-08-01

    What happens to the rain in highly urbanized catchments? That is the question that urban hydrologists must ask themselves when trying to integrate the hydrologic and hydraulic processes that affect the hydrologic response of urban catchments. The Illinois Urban Hydrologic Model (IUHM) has been developed to help answer this question and improve understanding and prediction of hydrologic response in highly urbanized catchments. Urban catchments are significantly different than natural watersheds, but there are similarities that allow features of the pioneering geomorphologic instantaneous unit hydrograph concept developed for natural watersheds to be adapted to the urban setting. This probabilistically based approach is a marked departure from the traditional deterministic models used to design and simulate urban sewer systems and does not have the burdensome input data requirements that detailed deterministic models possess. Application of IUHM to the CDS-51 catchment located in the village of Dolton, Illinois, highlights the model's ability to predict the hydrologic response of the catchment as well as the widely accepted SWMM model and is in accordance with observed data recorded by the United States Geological Survey. In addition, the unique structure and organization of urban sewer networks make it possible to characterize a set of ratios for urban catchments that allow IUHM to be applied when detailed input data are not available.

  16. 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.

  17. Relict rock glaciers as groundwater storage in alpine catchments - the example of the Seckauer Tauern Range

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas; Pauritsch, Marcus; Winkler, Gerfried

    2015-04-01

    Debris accumulations like relict rock glaciers (RRG) might act as groundwater storages in alpine catchments influencing the discharge dynamics of mountain streams. The degree of influence is related to the hydrometeorological conditions and changes seasonally. Especially during drought and flood events, the storage/buffer abilities of RRGs have an impact on the downstream river network. Stream flow could be assured during low flow periods and peak flows might be dampened during storm events. The assessment of the impact is investigated in the Seckauer Tauern Range, the easternmost subunit of the Niedere Tauern Range. In more detail, the discharge of a spring (Schöneben spring) emerging at the front of a RRG draining a catchment of 0.67 km² and discharges at gauging stations Finsterliesing and Unterwald further downstream with areal extents of 7.26 and 44.10 km² respectively are used as input for a lumped-parameter rainfall-runoff model, a modified version of the GR4J (Perrin et al., 2003). The Schöneben spring is 100% influenced by the RRG groundwater storage, as the whole catchment drains through the RRG. The flow dynamics of the other catchments are influenced only partially by RRGs with 15 and 12% as only headwater sections of it are drained by RRGs. The areal extend of the RRG (sub-) catchments, vegetation, debris in general and bare rock are compared to the storage parameters (routing and production store) of the rainfall-runoff model. As such, the influence of RRGs can be identified even in the overall catchment. It can be concluded that RRGs, due to their storage and buffer capabilities and abundance in the Seckauer Tauern Range are important for stream basin management and as a water resource for the sensitive ecosystem in alpine catchments. References: Perrin, C., Michel, C., Andréassian, V. (2003): Improvement of a parsimonious model for streamflow simulation. Journal of Hydrology 279, 275-289.

  18. Applying different spatial distribution and modelling concepts in three nested mesoscale catchments of Germany

    NASA Astrophysics Data System (ADS)

    Bongartz, K.

    Distributed, physically based river basin models are receiving increasing importance in integrated water resources management (IWRM) in Germany and in Europe, especially after the release of the new European Water Framework Directive (WFD). Applications in mesoscale catchments require an appropriate approach to represent the spatial distribution of related catchment properties such as land use, soil physics and topography by utilizing techniques of remote sensing and GIS analyses. The challenge is to delineate scale independent homogeneous modelling entities which, on the one hand may represent the dynamics of the dominant hydrological processes and, on the other hand can be derived from spatially distributed physiographical catchment properties. This scaling problem is tackled in this regional modelling study by applying the concept of hydrological response units (HRUs). In a nested catchment approach three different modelling conceptualisations are used to describe the runoff processes: (i) the topographic stream-segment-based HRU delineation proposed by Leavesley et al. [Precipitation-Runoff-Modelling-System, User’s Manual, Water Resource Investigations Report 83-4238, US Geological Survey, 1983]; (ii) the process based physiographic HRU-concept introduced by Flügel [Hydrol. Process. 9 (1995) 423] and (iii) an advanced HRU-concept adapted from (ii), which included the topographic topology of HRU-areas and the river network developed by Staudenraush [Eco Regio 8 (2000) 121]. The influence of different boundary conditions associated with changing the landuse classes, the temporal data resolution and the landuse scenarios were investigated. The mesoscale catchment of the river Ilm ( A∼895 km 2) in Thuringia, Germany, and the Precipitation-Runoff-Modelling-System (PRMS) were selected for this study. Simulations show that the physiographic based concept is a reliable method for modelling basin dynamics in catchments up to 200 km 2 whereas in larger catchments

  19. Linking the field to the stream: soil erosion and sediment yield in a rural catchment, NW Spain

    NASA Astrophysics Data System (ADS)

    Rodriguez-Blanco, M. L.; Taboada-Castro, M. M.; Palleiro-Suarez, L.; Taboada-Castro, M. T.

    2009-04-01

    Quantifying the linkages between field erosion, fluvial response and catchment sediment yield remains problematic, among other reasons, because of the re-deposition of eroded sediment within the catchment, which is controlled by the spatial organization of the land use and the connectivity between sediment sources and the stream network. This paper presents the results of an integrated study that considered the relationship between erosion and stream sediment yield in an agroforestry catchment (16 km2) in NW Spain. The geology consists of basic metamorphic schist. The relieve of the area is steeper, the mean slope is approximately 19%. Main soil types are classified as Umbrisol and Cambisol. Soils are acidic and rich in organic matter. The soil texture is silt and silt-loam. Land cover consists of a mixture of forest (65%) and agricultural fields (mainly grassland, pasture and maize). The study combined measurements of soil erosion by concentrate flow and sediment deposition at field scale with sediment yield measured at the catchment outlet. The hydrological data and water samples were obtained at the catchment outlet. Stream water level was monitored continuously and converted to discharge using a rating curve. The sampling for suspended sediments was supplemented by an automatic sampler. Suspended sediment load was calculated from the suspended sediment concentrations and discharge data. Eroded volume was calculated from cross-sections (measured at specific points, where the section changed abruptly) and length of the channel segments. The total sediment delivered to stream was determined as the difference between all erosion features (rills and gullies) and the sediment volumes that were deposited on the fields. The results showed that in the catchment during the period winter 2007/08 soil erosion by concentrate flow, i.e. rills and ephemeral gullies, occurred on unprotected crop field. Erosion by concentrate flow was highly discontinuous within the catchment

  20. Hydrogeomorphological and water quality impacts of oil palm conversion and logging in Sabah, Malaysian Borneo: a multi-catchment approach

    NASA Astrophysics Data System (ADS)

    Walsh, Rory; Nainar, Anand; Bidin, Kawi; Higton, Sam; Annammala, Kogilavani; Blake, William; Luke, Sarah; Murphy, Laura; Perryman, Emily; Wall, Katy; Hanapi, Jamil

    2016-04-01

    The last three decades have seen a combination of logging and land-use change across most of the rainforest tropics. This has involved conversion to oil palm across large parts of SE Asia. Although much is now known about the hydrological and sediment transport impacts of logging, relatively little is known about how impacts of oil palm conversion compare with those of logging. Furthermore little is known about the impacts of both on river morphology and water quality. This paper reports some findings of the first phase of a ten-year large-scale manipulative multi-catchment experiment (part of the SAFE - Stability of Altered Forest Ecosystems - Project), based in the upper part of the Brantian Catchment in Sabah, Malaysian Borneo; the project is designed to assess the degree to which adverse impacts of oil palm conversion (on erosion, downstream channel change, water quality and river ecology) might be reduced by retaining buffer zones of riparian forest of varying width from zero to 120 metres. Ten 2 km2 catchments of contrasting land use history have been instrumented since 2011 to record discharge, turbidity, conductivity and water temperature at 5-minute intervals. These comprise 6 repeat-logged catchments being subjected in 2015-16 to conversion to oil palm with varying riparian forest widths; a repeat-logged 'control' catchment; an old regrowth catchment; an oil palm catchment; and a primary forest catchment. In addition, (1) monthly water samples from the catchments have been analysed for nitrates and phosphates, (2) channel cross-sectional change along each stream has been monitored at six-monthly intervals and (3) supplementary surveys have been made of downstream bankfull channel cross-sectional size and water chemistry at a wider range of catchment sites, and (4) sediment cores have been taken and contemporary deposition monitored at a hierarchical network of sites in the large Brantian catchment for geochemical analysis and dating to establish the

  1. 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

    catchments are known for their rapid runoff generation and have downstream local communities at risk of flash flooding. In Bowmont, NFM measures are currently being put in place to restore river bars and to store water more effectively on the flood plains during these flashy events. For example, Apex engineered wood structure in the river channel and riparian zones are designed to trap sediment and log bank protection structures are being installed to stop bank erosion. Tree planting in the catchment is also taking place. In the Belford catchment storage ponds and woody debris have been installed over the past five years to help to reduce the flood risk to the village of Belford. A dense instrumentation network has provided data for analysis and modelling which shows evidence of local scale flood peak reductions along with the collection of large amounts of sediment. A modelling study carried out (using a pond network model) during an intense summer storm showed that 30 small scale pond features used in sequence could reduce the flood peak by ~35% at the local scale. Findings show that managing surface runoff and local ditch flow at local scale headwater catchments is a cost effective way of managing flashy catchment for flood risk and sediment control. Working with catchment stakeholders is vital. Information given by the local community post flooding has been useful in placing NFM measures throughout the catchments. Involving the local communities in these projects and giving them access to the data and model outputs has helped to develop these projects further.

  2. A perspective on stream-catchment connections

    USGS Publications Warehouse

    Bencala, Kenneth E.

    1993-01-01

    Ecological study of the hyporheic zone is leading to recognition of a need for additional hydrologic understanding. Some of this understanding can be obtained by viewing the hyporheic zone as a succession of isolated boxes adjacent to the stream. Further understanding, particularly relevant to catchment-scale ecology, may come from studies focussed on the fluid mechanics of the flow-path connections between streams and their catchments.

  3. Topic: Catchment system dynamics: Processes and feedbacks

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia

    2015-04-01

    In this meeting we can talk about my main expertise: the focus of my research ocus revolves around understanding catchment system dynamics in a holistic way by incorporating both processes on hillslopes as well as in the river channel. Process knowledge enables explanation of the impact of natural and human drivers on the catchment systems and which consequences these drivers have for water and sediment connectivity. Improved understanding of the catchment sediment and water dynamics will empower sustainable land and river management and mitigate soil threats like erosion and off-side water and sediment accumulation with the help of nature's forces. To be able to understand the system dynamics of a catchment, you need to study the catchment system in a holistic way. In many studies only the hillslopes or even plots are studied; or only the channel. However, these systems are connected and should be evaluated together. When studying a catchment system any intervention to the system will create both on- as well as off sites effects, which should especially be taken into account when transferring science into policy regulations or management decisions.

  4. The role of topography on catchment-scale water residence time

    USGS Publications Warehouse

    McGuire, K.J.; McDonnell, Jeffery J.; Weiler, M.; Kendall, C.; McGlynn, B.L.; Welker, J.M.; Seibert, J.

    2005-01-01

    The age, or residence time, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of water in a single integrated measure. While there has been tremendous recent interest in residence time estimation to characterize watersheds, there are relatively few studies that have quantified residence time at the watershed scale, and fewer still that have extended those results beyond single catchments to larger landscape scales. We examined-topographic controls on residence time for seven catchments (0.085-62.4 km2) that represent diverse geologic and geomorphic conditions in the western Cascade Mountains of Oregon. Our primary objective was to determine the dominant physical controls on catchment-scale, water residence time and specifically test the hypothesis that residence time is related to the size of the basin. Residence times were estimated by simple convolution models that described the transfer of precipitation isotopic composition to the stream network. We found that base flow mean residence times for exponential distributions ranged from 0.8 to 3.3 years. Mean residence time showed no correlation to basin area (r2 < 0.01) but instead was correlated (r2 =-0:91) to catchment terrain indices representing the flow path distance and flow path gradient to the stream network. These results illustrate that landscape organization (i.e., topography) rather than basin area controls catchment-scale transport. Results from this study may provide a framework for describing scale-invariant transport across climatic and geologic conditions, whereby the internal form and structure of the basin defines the first-order control on base flow residence time. Copyright 2005 by the American Geophysical Union.

  5. Shale to Regolith Evolution: The Controls on Catchment Solute Fluxes

    NASA Astrophysics Data System (ADS)

    Sullivan, Pamela; Goddéris, Yves; Shi, Yuning; Singha, Kamini; Clarke, Brian; Schott, Jacques; Duff, Chritopher; Brantley, Susan

    2014-05-01

    Understanding the factors that control the formation of regolith and the evolution of pore space within regolith as it is moves upward to the surface is of global importance. Unfortunately, both access and high costs have been prohibitive in gathering information about the bedrock-regolith boundary. Recognizing the need for data at depth, the Critical Zone Observatory (CZO) network initiated the "Drill the Ridge" project. The goal of this project is to investigate fresh bedrock at each CZO and then to perform an array of downhole geophysical survey and geochemical analyses to understand regolith formation. In response to this call, several ridgetop boreholes were drilled at the Susquehanna Shale Hills CZO in 2012 and 2013. Here we present the optical televiewer and gamma logs of these boreholes, along with downcore bulk geochemical analysis to shed light on the geochemical and lithological controls on the evolution of the watershed. Observations of catchment hydrology are also being used with estimates of hydrologic parameters to quantify near-surface geologic evolution and geochemical fluxes associated with weathering at depth. To quantify the contribution of weathering fluxes from the mobile regolith, we then link the meteorological forcing from the North American Land Data Assimilation System (NLDAS-2), the fully-coupled land-surface Penn State Integrated Hydrologic Model (Flux-PIHM), and the geochemical box model WITCH. With this cascade of models, solute fluxes for the CZO are being simulated. At depth, the bulk geochemical analysis of ridgetop sediments indicates that pyrite had the deepest depletion front, which was concurrent with the regional water table position. Hydrologic data together with detailed borehole and bulk soil/rock geochemical analysis elucidated an eastern to western progression in lithology across the SSHCZO catchment controls fracture distribution and thus groundwater flow. Where shale and mudstone underlie the eastern portion of

  6. Networks.

    ERIC Educational Resources Information Center

    Maughan, George R.; Petitto, Karen R.; McLaughlin, Don

    2001-01-01

    Describes the connectivity features and options of modern campus communication and information system networks, including signal transmission (wire-based and wireless), signal switching, convergence of networks, and network assessment variables, to enable campus leaders to make sound future-oriented decisions. (EV)

  7. Assessing the simple dynamical systems approach in a Mediterranean context: application to the Ardeche catchment (France)

    NASA Astrophysics Data System (ADS)

    Adamovic, M.; Braud, I.; Branger, F.; Kirchner, J. W.

    2015-05-01

    This study explores how catchment heterogeneity and variability can be summarized in simplified models, representing the dominant hydrological processes. It focuses on Mediterranean catchments, characterized by heterogeneous geology, pedology and land use, as well as steep topography and a rainfall regime in which summer droughts contrast with high-rainfall periods in autumn. The Ardeche catchment (Southeast France), typical of this environment, is chosen to explore the following questions: (1) can such a Mediterranean catchment be adequately characterized by a simple dynamical systems approach and what are the limits of the method under such conditions? (2) what information about dominant predictors of hydrological variability can be retrieved from this analysis in such catchments? In this work we apply the data-driven approach of Kirchner (2009) to estimate discharge sensitivity functions that summarize the behaviour of four sub-catchments of the Ardeche, using low-vegetation periods (November-March) from 9 years of measurements (2000-2008) from operational networks. The relevance of the inferred sensitivity function is assessed through hydrograph simulations, and through estimating precipitation rates from discharge fluctuations. We find that the discharge sensitivity function is downward-curving in double-logarithmic space, thus allowing further simulation of discharge and non-divergence of the model, only during low-vegetation periods. The analysis is complemented by a Monte Carlo sensitivity analysis showing how the parameters summarizing the discharge sensitivity function impact the simulated hydrographs. The resulting discharge simulation results are good for granite catchments, which are likely to be characterized by shallow subsurface flow at the interface between soil and bedrock. The simple dynamical system hypothesis works especially well in wet conditions (peaks and recessions are well modelled). On the other hand, poor model performance is associated

  8. Inductive machine learning for improved estimation of catchment-scale snow water equivalent

    NASA Astrophysics Data System (ADS)

    Buckingham, David; Skalka, Christian; Bongard, Josh

    2015-05-01

    Infrastructure for the automatic collection of single-point measurements of snow water equivalent (SWE) is well-established. However, because SWE varies significantly over space, the estimation of SWE at the catchment scale based on a single-point measurement is error-prone. We propose low-cost, lightweight methods for near-real-time estimation of mean catchment-wide SWE using existing infrastructure, wireless sensor networks, and machine learning algorithms. Because snowpack distribution is highly nonlinear, we focus on Genetic Programming (GP), a nonlinear, white-box, inductive machine learning algorithm. Because we did not have access to near-real-time catchment-scale SWE data, we used available data as ground truth for machine learning in a set of experiments that are successive approximations of our goal of catchment-wide SWE estimation. First, we used a history of maritime snowpack data collected by manual snow courses. Second, we used distributed snow depth (HS) data collected automatically by wireless sensor networks. We compared the performance of GP against linear regression (LR), binary regression trees (BT), and a widely used basic method (BM) that naively assumes non-variable snowpack. In the first experiment set, GP and LR models predicted SWE with lower error than BM. In the second experiment set, GP had lower error than LR, but outperformed BT only when we applied a technique that specifically mitigated the possibility of over-fitting.

  9. Transport of cyazofamid and kresoxim methyl in runoff at the plot and catchment scales

    NASA Astrophysics Data System (ADS)

    Lefrancq, Marie; Joaquín García Verdú, Antonio; Maillard, Elodie; Imfeld, Gwenaël; Payraudeau, Sylvain

    2013-04-01

    Surface runoff and erosion during the course of rainfall events represent major processes of pesticides transport from agricultural land to aquatic ecosystem. In general, field and catchment studies on pesticide transfer are carried out separately. A study at both scales may enable to improve the understanding of scale effects on processes involved in pesticides transport and to give clues on the source areas within an agricultural catchment. In this study, the transport in runoff of two widely used fungicides, i.e. kresoxim methyl (KM) and cyazofamid (CY) was assessed in a 43 ha vineyard catchment and the relative contribution of the total fungicides export from one representative plot was evaluated. During an entire period of fungicide application, from May to August 2011, the discharge and loads of dissolved and particle-laden KM and CY were monitored at the plot and catchment scales. The results showed larger export coefficient of KM and CY from catchment (0.064 and 0.041‰ for KM and CY respectively) than from the studied plot (0.009 and 0.023 ‰ for KM and CY respectively). It suggests that the plot margins especially the road network contributed as well to the fungicide loads. This result underlines the impact of fungicide drift on non-target areas. Furthermore, a larger rainfall threshold is necessary at the plot scale to trigger runoff and mobilise pesticides than on the road network. At the plot scale, a rapid dissipation of the both fungicides in the top soil was observed. It highlights that the risky period encompasses the first rainfall events triggering runoff after the applications. At both scales, KM and CY were not detected in suspended solids (i.e. > 0.7 µm). However their partitioning in runoff water differed. 64.1 and 91.8% of the KM load was detected in the dissolved phase (i.e. < 0.22 µm) at the plot and catchment scales respectively, whereas 98.7 and 100% of the CY load was detected in the particulate phase (i.e. between 0.22 and 0.7 µm

  10. Catchment biophysical drivers of streamflow characteristics

    NASA Astrophysics Data System (ADS)

    Trancoso, R.

    2015-12-01

    The characteristics of streamflow reflect the co-evolution of climate, soils, topography and vegetation of catchments. Hydrological metrics or signatures can represent the long-term behaviour and integrate the influence of all the streamflow drivers. Although this sort of relationship has been developed in regional studies exploring prediction of Flow Duration Curves and other streamflow metrics, little is known about the controls of other key streamflow characteristics especially in continent scale. This study aims to understand how catchment biophysical variables control key hydrological metrics such as baseflow index, elasticity of streamflow to rainfall variability and intermittency in continent scale and regionally. We used a set of catchment biophysical variables to model key streamflow signatures using multivariate power-law and beta regressions in 355 catchments located along the eastern Australian seaboard. Streamflow signatures were derived from daily streamflow time series data from 1980 to 2013. We tested 52 catchment biophysical characteristics related to climate, soil, topography, geography, geomorphology, vegetation and land-cover as predictors of the streamflow signatures. The prediction R-squared ranged from 63 to 72% when relationships are built in continent scale, but can be greater than 80% when regressions are regionalised. The interpretation of the modelled relationships offers new insights regarding the controls of flow characteristics.

  11. In Lieu of the Paired-Catchment Approach - Hydrologic Model Change Detection at the Catchment Scale

    NASA Astrophysics Data System (ADS)

    Zegre, N. P.

    2009-05-01

    Knowledge of the effects of forest management on hydrology primarily comes from paired-catchment studies conducted world-wide. While this approach has been useful for discerning changes in small experimental catchments and has contributed fundamental knowledge of the effects of forest and natural resources management on hydrology, results from experimental catchment studies exhibit temporal variability, have limited spatial inference, and lack insight into internal catchment processes. To address these limitations, traditional field experiments can be supplemented with numerical models to isolate the effects of disturbance on catchment behavior. Outlined in this study is an alternative method of change detection for daily time-series streamflow that integrates hydrologic modeling and statistical change detection methods used to discern the effects of contemporary forest management on the hydrology of western Oregon Cascades headwater catchments. In this study, a simple rainfall-runoff model was used to generate virtual reference catchments using attributes that reflect streamflow conditions absent of forest disturbance. Streamflow was simulated under three levels of model uncertainty using GLUE and were used to construct generalized least squares regression models to discern changes in hydrologic behavior. By considering processes within a single experimental catchment rather than the two spatially explicit catchments used in traditional paired experiments, it was possible to reduce unexplained variation and increase the likelihood of correctly detecting hydrologic effects following forest harvesting. In order to evaluate the stability of the hydrologic and statistical models and catchment behavior over time, the change detection method was applied to a contemporary reference catchment. By applying the change detection model to reference catchments, it was possible to eliminate unexpected variation as a cause for detected changes in observed hydrology. Further, it

  12. Quantifying in-stream retention of nitrate at catchment scales using a practical mass balance approach.

    PubMed

    Schwientek, Marc; Selle, Benny

    2016-02-01

    As field data on in-stream nitrate retention is scarce at catchment scales, this study aimed at quantifying net retention of nitrate within the entire river network of a fourth-order stream. For this purpose, a practical mass balance approach combined with a Lagrangian sampling scheme was applied and seasonally repeated to estimate daily in-stream net retention of nitrate for a 17.4 km long, agriculturally influenced, segment of the Steinlach River in southwestern Germany. This river segment represents approximately 70% of the length of the main stem and about 32% of the streambed area of the entire river network. Sampling days in spring and summer were biogeochemically more active than in autumn and winter. Results obtained for the main stem of Steinlach River were subsequently extrapolated to the stream network in the catchment. It was demonstrated that, for baseflow conditions in spring and summer, in-stream nitrate retention could sum up to a relevant term of the catchment's nitrogen balance if the entire stream network was considered.

  13. 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.

  14. What can we learn from the hydrological modeling of small-scale catchments for the discharge and water balance modeling of mesoscale catchments?

    NASA Astrophysics Data System (ADS)

    Cornelissen, Thomas; Diekkrüger, Bernd; Bogena, Heye

    2015-04-01

    The application of 3D hydrological models remains a challenge both in research and application studies because the parameterization not only depends on the amount and quality of data available for calibration and validation but also on the spatial and temporal model resolution. In recent years, the model parameterization has improved with the availability of high resolution data (e.g. eddy-covariance, wireless soil sensor networks). Unfortunately, these high resolution data are typically only available for small scale research test sites. This study aims to upscale the parameterization from a highly equipped, small-scale catchment to a mesoscale catchment in order to reduce the parameterization uncertainty at that scale. The two nested catchments chosen for the study are the 0.38 km² large spruce covered Wüstebach catchment and the 42 km² large Erkensruhr catchment characterized by a mixture of spruce and beech forest and grassland vegetation. The 3D hydrogeological model HydroGeoSphere (HGS) has already been setup for the Wüstebach catchment in a previous study with a focus on the simulation performance of soil water dynamics and patterns. Thus, the parameterization process did not only optimize the water balance components but the catchment's wireless soil sensor network data were utilized to calibrate porosities in order to improve the simulation of soil moisture dynamics. In this study we compared different HGS model realizations for the Erkensruhr catchment with different input data. For the first model realization, the catchment is treated heterogeneous in terms of soil properties and topography but homogeneous with respect to land use, precipitation and potential evapotranspiration. For this case, the spruce forest parameterization and the climate input data were taken directly from the small-scale Wüstebach model realization. Next, the calibrated soil porosity for the Wüstebach catchment is applied to the Erkensruhr. Further model realizations

  15. Seasonalstreamflow Generation At Variousspatial Scales On A Smallmediterranean Vineyard Catchment

    NASA Astrophysics Data System (ADS)

    Marofi, S.; Moussa, R.; Voltz, M.

    The importance of surface hydrological processes, under field and sub-catchment conditions, was examines on a small-cultivated watershed, located in South of France. Hydrological responses at different spatial scales were evaluated during the wetness and drier phases, which included the within-year and the long-term periods. The experimental design involved monitoring of surface runoff, streamflow and groundwaters behaviours, in response to rainfall events, during three hydrological cycles. In addition to the mean outlet of catchment and the two vineyard fields that have different situations, runoff was measured at 8 sub-catchments of site. Rainfall was monitored on continuous basis at 4 sites, and the water tables fluctuations also were recorded in more than 15 locations of catchment. During the experimentation period, more than 175 rainy events were observed. The dates analyse show that the regime of surface water, compound of three principals phases: (i) the phases of great flow circulation, (ii) the recession phases, and (iii) the phase without surface flow. The results also indicate that the annual runoff changes appreciably according to hydrological cycles and the rainfall variability. It varies from 28% to 50% of the total of precipitation. The inter-annual variations of the runoff also recovers that the annual runoff flow is insured for approximately 40% by the instantaneous floods, which occur the moment or a few hours only after precipitation, and about 60% by the recession periods, which take place for the long time after floods. The flood events were classified in three groups, differentiated by the initial water table levels and their occurrence period. The direct runoff and the baseflow calculation show that according to the type of flood, they change respectively from 7% to17% and 0% to 7% of precipitation. Comparing to the field areas, on average, the total runoff and direct runoff of the mean basin respectively are 46% and 35%. The water flow

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

    PubMed

    Hughes, Andrew O; Quinn, John M

    2014-12-01

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

  17. 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.

  18. 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

  19. Contrasting Patterns of Fine Fluvial Sediment Delivery in Two Adjacent Upland Catchments

    NASA Astrophysics Data System (ADS)

    Perks, M.; Bracken, L.; Warburton, J.

    2010-12-01

    Quantifying patterns of fine suspended sediment transfer in UK upland rivers is of vital importance in combating the damaging effects of elevated fluxes of suspended sediment, and sediment associated transport of contaminants, on in-stream biota. In many catchments of the UK there is still a lack of catchment-wide understanding of both the spatial patterns and temporal variation in fine sediment delivery. This poster describes the spatial and temporal distribution of in-stream fine sediment delivery from a network of 44 time-integrated mass flux samplers (TIMs) in two adjacent upland catchments. The two catchments are the Esk (210 km2) and Upper Derwent (236 km2) which drain the North York Moors National Park. Annual suspended sediment loads in the Upper Derwent are 1273 t, whereas in the Esk catchment they are greater at 1778 t. Maximum yields of 22 t km-2 yr -1 were measured in the headwater tributaries of the Rye River (Derwent), whereas peak yields in the Esk are four times greater (98 t km-2 yr-1) on the Butter Beck subcatchment. Analysis of the within-storm sediment dynamics, indicates that the sediment sources within the Upper Derwent catchment are from distal locations possibly mobilised by hillslope runoff processes, whereas in the Esk, sediment sources are more proximal to the channel e.g. within channel stores or bank failures. These estimates of suspended sediment flux are compared with the diffuse pollution potential generated by a risk-based model of sediment transfer (SCIMAP) in order to assess the similarity between the model predictions and observed fluxes.

  20. Validation of Pacific Northwest hydrologic landscapes at the catchment scale

    EPA Science Inventory

    The interaction between the physical properties of a catchment (form) and climatic forcing of precipitation and energy control how water is partitioned, stored, and conveyed through a catchment (function). Hydrologic Landscapes (HLs) were previously developed across Oregon and de...

  1. Environmental isotope hydrology of salinized experimental catchments

    NASA Astrophysics Data System (ADS)

    Turner, J. V.; Arad, A.; Johnston, C. D.

    1987-10-01

    Deuterium, oxygen-18, tritium and chloride concentrations were used in three salinized experimental catchments to gain insight into the mechanism of solute concentration and flow processes in the saturated and unsaturated zones. The three experimental catchments were studied because of their location in different rainfall regions, their status with respect to clearing of native vegetation and with respect to secondary salinization. Two uncleared catchments have average annual rainfalls of approximately 820 and 1220 mm, respectively. The third cleared catchment has an annual rainfall of 650-750 mm. This catchment was in an advanced state of secondary salinization and displayed large areas of saline groundwater discharge with halite encrustation at the ground surface. The stable isotope compositions of the solution phase in solute bulge profiles in the unsaturated zone showed a close agreement with the amount-weighted mean isotopic composition of rainfall and only surficial evidence of isotopic enrichment due to evaporation. Evaporation from the soil surface plays a minor role as a mechanism of solute concentration in the unsaturated zone. The dominant process of solute concentration in the unsaturated zone was ion exclusion during uptake of water by tree roots which was evidently a solute but not isotope fractionating process. Tritium analyses of unsaturated zone water and grondwater indicated movement of recent recharge to 7-10 m depth at the low rainfall site but over the full depth of the 15 m unsaturated zone at the higher rainfall site. The variability in δ18O and δ2H values of groundwaters was used in association with chloride concentrations to provide information on mixing characteristics of groundwaters within the catchments.

  2. Picturing and modelling catchments by representative hillslopes

    NASA Astrophysics Data System (ADS)

    Loritz, Ralf; Hassler, Sibylle; Jackisch, Conrad; Zehe, Erwin

    2016-04-01

    Hydrological modelling studies often start with a qualitative sketch of the hydrological processes of a catchment. These so-called perceptual models are often pictured as hillslopes and are generalizations displaying only the dominant and relevant processes of a catchment or hillslope. The problem with these models is that they are prone to become too much predetermined by the designer's background and experience. Moreover it is difficult to know if that picture is correct and contains enough complexity to represent the system under study. Nevertheless, because of their qualitative form, perceptual models are easy to understand and can be an excellent tool for multidisciplinary exchange between researchers with different backgrounds, helping to identify the dominant structures and processes in a catchment. In our study we explore whether a perceptual model built upon an intensive field campaign may serve as a blueprint for setting up representative hillslopes in a hydrological model to reproduce the functioning of two distinctly different catchments. We use a physically-based 2D hillslope model which has proven capable to be driven by measured soil-hydrological parameters. A key asset of our approach is that the model structure itself remains a picture of the perceptual model, which is benchmarked against a) geo-physical images of the subsurface and b) observed dynamics of discharge, distributed state variables and fluxes (soil moisture, matric potential and sap flow). Within this approach we are able to set up two behavioral model structures which allow the simulation of the most important hydrological fluxes and state variables in good accordance with available observations within the 19.4 km2 large Colpach catchment and the 4.5 km2 large Wollefsbach catchment in Luxembourg without the necessity of calibration. This corroborates, contrary to the widespread opinion, that a) lower mesoscale catchments may be modelled by representative hillslopes and b) physically

  3. Identification of internal flow dynamics in two experimental catchments

    USGS Publications Warehouse

    Hansen, D.P.; Jakeman, A.J.; Kendall, C.; Weizu, G.

    1997-01-01

    Identification of the internal flow dynamics in catchments is difficult because of the lack of information in precipitation -stream discharge time series alone. Two experimental catchments, Hydrohill and Nandadish, near Nanjing in China, have been set up to monitor internal flows reaching the catchment stream at various depths, from the surface runoff to the bedrock. With analysis of the precipitation against these internal discharges, it is possible to quantify the time constants and volumes associated with various flowpaths in both catchments.

  4. Siting analyses for water quality sampling in a catchment.

    PubMed

    Kao, Jehng-Jung; Li, Pei-Hao; Lin, Chin-Lien; Hu, Wen-Hsin

    2008-04-01

    Pollution loads discharged from upstream development or human activities significantly degrade the water quality of a reservoir. The design of an appropriate water quality sampling network is therefore important for detecting potential pollution events and monitoring pollution trends. However, under a limited budgetary constraint, how to site an appropriate number of sampling stations is a challenging task. A previous study proposed a method applying the simulated annealing algorithm to design the sampling network based on three cost factors including the number of reaches, bank length, and subcatchment area. However, these factors are not directly related to the distribution of possible pollution. Thus, this study modified the method by considering three additional factors, i.e. total phosphorus, nitrogen, and sediment loads. The larger the possible load, the higher the probability of a pollution event may occur. The study area was the Derchi reservoir catchment in Taiwan. Pollution loads were derived from the AGNPS model with rainfall intensity estimated using the Thiessen method. Analyses for a network with various numbers of sampling sites were implemented. The results obtained based on varied cost factors were compared and discussed. With the three additional factors, the chosen sampling network is expected to properly detect pollution events and monitor pollution distribution and temporal trends.

  5. Networking.

    ERIC Educational Resources Information Center

    Duvall, Betty

    Networking is an information giving and receiving system, a support system, and a means whereby women can get ahead in careers--either in new jobs or in current positions. Networking information can create many opportunities: women can talk about how other women handle situations and tasks, and previously established contacts can be used in…

  6. Parsimonious hydrological modeling of urban sewer and river catchments

    NASA Astrophysics Data System (ADS)

    Coutu, Sylvain; Del Giudice, Dario; Rossi, Luca; Barry, D. A.

    2012-09-01

    SummaryA parsimonious model of flow capable of simulating flow in natural/engineered catchments and at WWTP (Wastewater Treatment Plant) inlets was developed. The model considers three interacting, dynamic storages that account for transfer of water within the system. One storage describes the “flashy” response of impervious surfaces, another pervious areas and finally one storage describes subsurface flow. The sewerage pipe network is considered as an impervious surface and is thus included in the impervious surface storage. In addition, the model assumes that water discharged from several CSOs (combined sewer overflows) can be accounted for using a single, characteristic CSO. The model was calibrated on, and validated for, the Vidy Bay WWTP, which receives effluent from Lausanne, Switzerland (population about 200,000), as well as for an overlapping urban river basin. The results indicate that a relatively simple approach is suitable for predicting the responses of interacting engineered and natural hydrosystems.

  7. Influence of urbanization pattern on stream flow of a peri-urban catchment under Mediterranean climate

    NASA Astrophysics Data System (ADS)

    Ferreira, Carla S. S.; Walsh, Rory P. D.; Ferreira, António J. D.; Steenhuis, Tammo S.; Coelho, Celeste A. O.

    2015-04-01

    . Percentage impermeable surface seems to control streamflow particularly during dry periods. Winter runoff was 2-4 times higher than total river flow in the summer dry season in highly urbanized areas, but was 21-fold higher in winter in the least urbanized sub-catchment, denoting greater flow connectivity enhanced by increased soil moisture. Although impermeable surfaces are prone to generate overland flow, the proximity to the stream network is an important parameter determining their hydrological impacts. During the monitoring period, the enlargement of 2% of the urban area at downslope locations in the Covões sub-catchment, led to a 6% increase in the runoff coefficient. In contrast, the urban area increase from 9 to 25% mainly in upslope parts of the Quinta sub-catchment did not increase the peak streamflow due to downslope infiltration and surface retention opportunities. Despite impermeable surfaces enhance overland flow, some urban features (e.g. walls and road embankments) promote surface water retention. The presence of artificial drainage systems, on the other hand, enhances flow connectivity, leading to increasing peak flow and quicker response times (~10 minutes versus 40-50 minutes) as in the Covões sub-catchment. Urbanization impact on streamflow responses may be minimized through planning the land-use mosaic so as to maximize infiltration opportunities. Knowledge of the influence of distinct urban mosaics on flow connectivity and stream discharge is therefore important to landscape managers and should guide urban planning in order to minimize flood hazards.

  8. Integrating structural and functional connectivity to characterize sediment dynamics in a small Alpine catchment

    NASA Astrophysics Data System (ADS)

    Cavalli, Marco; Crema, Stefano; Blok, Michiel; Lucía, Ana; Comiti, Francesco; Marchi, Lorenzo; Keesstra, Saskia

    2016-04-01

    Sediment connectivity can be regarded as a descriptor of the internal linkages between different landscape components within a catchment. The recent focus of the scientific community on connectivity related topics, both concerning hydrological and sediment connectivity, stresses the importance of understanding the main active pathways for a better estimation of energy and matter transfer at catchment scale. This task can be addressed using topography-based indices that analyse the linkages between landscape units. This approach to characterize connectivity is known as structural connectivity. The main limitation of structural connectivity is that it does not account for the processes driving sediment and energy fluxes (i.e., functional connectivity). In this work the integration between structural and functional approaches is proposed for characterizing sediment connectivity in mountain catchments. The structural approach, based on a topography-based sediment connectivity index, was used for assessing hillslope-to-channel connectivity. Since field data on processes driving sediment transport along the channel network are available, a functional approach has been devised to estimate within-channel connectivity. An index of unit stream power computed from the hydraulic properties of the channel (i.e., discharge, slope and channel width) has been compared with the critical unit stream power computed from incipient motion thresholds derived from field data to identify the cells of the Digital Terrain Model (DTM) in which sediment can be mobilized under near-bankfull conditions. The index expressing the within-channel connectivity is given by the length of the reaches consisting of contiguous cells that exceed the critical unit stream power. During high-magnitude floods, when unit stream power values exceed the threshold for incipient motion, channels experience an increase in both hydrological and sediment connectivity. The proposed index characterizes those sections

  9. Simultaneous occurrences of floods in mesoscale catchments

    NASA Astrophysics Data System (ADS)

    Bàrdossy, Andràs

    2016-04-01

    Floods in mesoscale catchments are often the result of intense precipitation of varying duration. The spatial extent of precipitation is linked to the extent of flooding. The simultaneous occurrence of floods in different medium size catchments is often the reason for large scale floods. The spatial behavior of extreme precipitation and discharge can be investigated using copulas and extreme indices. The relationship between intense precipitations measured at different locations depends on the large scale meteorological conditions. Depending on the geographic location and the dominating weather pattern certain catchments have frequent simultaneous extremes while others behave in a complementary fashion. The purpose of this work is to investigate the simultaneous and complementary occurrence of floods in catchments using copulas conditioned on atmospheric circulation patterns (CPs). Circulation patterns responsible for simultaneous floods are identified using areal precipitation and/or unusual discharge increases. Patterns are identified using a fuzzy rule based approach based on anomalies of the 700 hPa surfaces. The rules are formed by maximizing the explained variance under the assumption of simultaneous and complementary behavior. The conditional copulas are investigated for extreme behavior. Besides the traditional bivariate investigations higher dimensional dependences are investigated using an entropy based approach.

  10. 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...

  11. Hydrological Modelling of Small Catchments Using Swat

    NASA Astrophysics Data System (ADS)

    Kannan, N.; White, S. M.; Worrall, F.; Groves, S.

    The data from a 142ha catchment in Eastern England(Colworth, Bedfordshire)are be- ing used to investigate the performance of the USDA SWAT software for modelling hydrology of small catchments. Stream flow at the catchment outlet has been mon- itored since October 1999. About 50% of the total catchment is directly controlled within one farm and a rotation of wheat, oil seed rape, grass, linseed, beans and peas is grown. Three years of stream flow and climate data are available. Calibration and validation of stream flow was carried out with both runoff modelling options in the SWAT model (USDA curve number method and the Green and Ampt method). The Nash and Sutcliffe efficiencies for the calibration period were 66% and 63% respec- tively. The performance of SWAT was better in the validation period as a whole, with regard to timing of peaks, baseflow values and Nash and Sutcliffe efficiency. An ef- ficiency of 70% was obtained using the curve number method, which is comparable with the efficiencies obtainable with more complex models. Despite this performance, SWAT is under predicting stream flow peaks. A detailed investigation of important model components, has allowed us to identify some of the reasons for under predic- tion of stream flow peaks.

  12. Catchment scale afforestation for mitigating flooding

    NASA Astrophysics Data System (ADS)

    Barnes, Mhari; Quinn, Paul; Bathurst, James; Birkinshaw, Stephen

    2016-04-01

    After the 2013-14 floods in the UK there were calls to 'forest the uplands' as a solution to reducing flood risk across the nation. At present, 1 in 6 homes in Britain are at risk of flooding and current EU legislation demands a sustainable, 'nature-based solution'. However, the role of forests as a natural flood management technique remains highly controversial, due to a distinct lack of robust evidence into its effectiveness in reducing flood risk during extreme events. SHETRAN, physically-based spatially-distributed hydrological models of the Irthing catchment and Wark forest sub-catchments (northern England) have been developed in order to test the hypothesis of the effect trees have on flood magnitude. The advanced physically-based models have been designed to model scale-related responses from 1, through 10, to 100km2, a first study of the extent to which afforestation and woody debris runoff attenuation features (RAFs) may help to mitigate floods at the full catchment scale (100-1000 km2) and on a national basis. Furthermore, there is a need to analyse the extent to which land management practices, and the installation of nature-based RAFs, such as woody debris dams, in headwater catchments can attenuate flood-wave movement, and potentially reduce downstream flood risk. The impacts of riparian planting and the benefits of adding large woody debris of several designs and on differing sizes of channels has also been simulated using advanced hydrodynamic (HiPIMS) and hydrological modelling (SHETRAN). With the aim of determining the effect forestry may have on flood frequency, 1000 years of generated rainfall data representative of current conditions has been used to determine the difference between current land-cover, different distributions of forest cover and the defining scenarios - complete forest removal and complete afforestation of the catchment. The simulations show the percentage of forestry required to have a significant impact on mitigating

  13. Innovative framework to simulate the fate and transport of nonconservative constituents in urban combined sewer catchments

    NASA Astrophysics Data System (ADS)

    Morales, V. M.; Quijano, J. C.; Schmidt, A.; Garcia, M. H.

    2016-11-01

    We have developed a probabilistic model to simulate the fate and transport of nonconservative constituents in urban watersheds. The approach implemented here extends previous studies that rely on the geomorphological instantaneous unit hydrograph concept to include nonconservative constituents. This is implemented with a factor χ that affects the transfer functions and therefore accounts for the loss (gain) of mass associated with the constituent as it travels through the watershed. Using this framework, we developed an analytical solution for the dynamics of dissolved oxygen (DO) and biochemical oxygen demand (BOD) in urban networks based on the Streeter and Phelps model. This model breaks down the catchment into a discreet number of possible flow paths through the system, requiring less data and implementation effort than well-established deterministic models. Application of the model to one sewer catchment in the Chicago area with available BOD information proved its ability to predict the BOD concentration observed in the measurements. In addition, comparison of the model with a calibrated Storm Water Management Model (SWMM) of another sewer catchment from the Chicago area showed that the model predicted the BOD concentration as well as the widely accepted SWMM. The developed model proved to be a suitable alternative to simulate the fate and transport of constituents in urban catchments with limited and uncertain input data.

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

    PubMed

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

    2011-11-30

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

  15. Variability of rainfall over Lake Kariba catchment area in the Zambezi river basin, Zimbabwe

    NASA Astrophysics Data System (ADS)

    Muchuru, Shepherd; Botai, Joel O.; Botai, Christina M.; Landman, Willem A.; Adeola, Abiodun M.

    2016-04-01

    In this study, average monthly and annual rainfall totals recorded for the period 1970 to 2010 from a network of 13 stations across the Lake Kariba catchment area of the Zambezi river basin were analyzed in order to characterize the spatial-temporal variability of rainfall across the catchment area. In the analysis, the data were subjected to intervention and homogeneity analysis using the Cumulative Summation (CUSUM) technique and step change analysis using rank-sum test. Furthermore, rainfall variability was characterized by trend analysis using the non-parametric Mann-Kendall statistic. Additionally, the rainfall series were decomposed and the spectral characteristics derived using Cross Wavelet Transform (CWT) and Wavelet Coherence (WC) analysis. The advantage of using the wavelet-based parameters is that they vary in time and can therefore be used to quantitatively detect time-scale-dependent correlations and phase shifts between rainfall time series at various localized time-frequency scales. The annual and seasonal rainfall series were homogeneous and demonstrated no apparent significant shifts. According to the inhomogeneity classification, the rainfall series recorded across the Lake Kariba catchment area belonged to category A (useful) and B (doubtful), i.e., there were zero to one and two absolute tests rejecting the null hypothesis (at 5 % significance level), respectively. Lastly, the long-term variability of the rainfall series across the Lake Kariba catchment area exhibited non-significant positive and negative trends with coherent oscillatory modes that are constantly locked in phase in the Morlet wavelet space.

  16. Non-linearities in hydrological connectivity and microbiological flux in nested catchments - implications of environmental change

    NASA Astrophysics Data System (ADS)

    Tetzlaff, D.; Soulsby, C.; Birkel, C.; Capell, R.; Speed, M.

    2009-12-01

    The non-linearities of catchment hydrological behaviour are strongly influenced by the connectivity of hillslopes and channel networks, particularly where overland flow is an important runoff mechanism. Such surface connectivity also controls the flux of microbiological pollutants (coliform bacteria) from areas of live stock grazing which can have serious health implications for potable water supplies. We report a nested catchment study where hydrological and tracer monitoring over a two year period has been coupled with regular sampling for faecal indicator organisms (FIOs). The study has been based in catchments with mixed landuse where FIOs are derived from livestock (sheep and cows) in agricultural land and wild animals (red deer) on moorlands. At all scales (3-1800km2), high levels of FIO were transient and episodic and strongly correlated with periods of high hydrological connectivity. We show how this non-linearity in connectivity can be captured within a dynamic hydrological model. The model was used, along with climate change predictions, to assess possible scenarios of change in connectivity and microbiological contamination in catchments with different land use.

  17. Assessing the applicability of the Revised Universal Soil Loss Equation (RUSLE) to Irish Catchments

    NASA Astrophysics Data System (ADS)

    Rymszewicz, A.; Mockler, E.; O'Sullivan, J.; Bruen, M.; Turner, J.; Conroy, E.; Kelly-Quinn, M.; Harrington, J.; Lawler, D.

    2015-03-01

    Elevated suspended sediment concentrations in fluvial environments have important implications for system ecology and even small concentrations may have serious consequences for sensitive ecosystems or organisms, such as freshwater pearl mussels (Margaritifera margaritifera). Informed decision making is therefore required for land managers to understand and control soil erosion and sediment delivery to the river network. However, given that monitoring of sediment fluxes requires financial and human resources which are often limited at a national scale, sediment mobilisation and delivery models are commonly used for sediment yield estimation and management. The Revised Universal Soil Loss Equation (RUSLE) is the most widely used model for overland flow erosion and can, when combined with a sediment delivery ratio (SDR), provide reasonable sediment load estimations for a catchment. This paper presents RUSLE factors established from extant GIS and rainfall datasets that are incorporated into a flexible catchment modelling approach. We believe that this is the first time that results from a RUSLE application at a national scale are tested against measured sediment yield values available from Ireland. An initial assessment of RUSLE applied to Irish conditions indicates an overestimation of modelled sediment yield values for most of the selected catchments. Improved methods for model and SDR factors estimation are needed to account for Irish conditions and catchment characteristics. Nonetheless, validation and testing of the model in this study using observed values is an important step towards more effective sediment yield modelling tools for nationwide applications.

  18. Inferring the effect of catchment complexity on mesoscale hydrologic response

    NASA Astrophysics Data System (ADS)

    FröHlich, Holger L.; Breuer, Lutz; Vaché, Kellie B.; Frede, Hans-Georg

    2008-09-01

    The effect of catchment complexity on hydrologic and hydrochemical catchment response was characterized in the mesoscale Dill catchment (692 km2), Germany. This analysis was developed using multivariate daily stream concentration and discharge data at the basin outlet, in connection with less frequently sampled catchment-wide end-member chemistries. The link between catchment-wide runoff sources and basin output was observed through a combination of concentration-discharge (C-Q) analysis and multivariate end-member projection. Subsurface stormflow, various groundwater and wastewater sources, as well as urban surface runoff emerged in catchment output chemistry. Despite the identification of multiple sources, several runoff sources observed within the catchment failed to display consistent links with the output chemistry. This failure to associate known source chemistry with outlet chemistry may have resulted from a lack of hydraulic connectivity between sources and basin outlet, from different arrival times of subbasin-scale runoff contributions, and also from an overlap of source chemistries that subsumed discrete runoff sources in catchment output. This combination of catchment heterogeneity and complexity simply suggests that the internal spatial organization of the catchment impeded the application of lumped mixing calculations at the 692 km2 outlet. Given these challenges, we suggest that in mesoscale catchment research, the potential effects of spatial organization should be included in any interpretation of highly integrated response signals, or when using those signals to evaluate numerical rainfall-runoff models.

  19. Characterizing hot spots throughout the catchment

    NASA Astrophysics Data System (ADS)

    Welti, N.; Lockington, D.; Jakeman, T.; Hunt, R.

    2012-04-01

    Few catchments in the world are left truly undisturbed. Rather, they are under anthropogenic stress for a variety of reasons ranging from climate forcing to meeting the basic water allocation needs of the population. Reduction in the number of inundation areas has significantly decreased the nutrient and organic matter retention capacity along the river corridor, with major consequences for the both the riverine and coastal ecosystems. Cumulative stress may build up to a "tipping point" which can cause a change or set of changes which could occur non-linearly. In order to mitigate the environmental stress on these ecosystems, management plans are created to balance the needs of the dependent populations and those of ecology. While these catchment-wide plans aim to improve the ecological function of aquatic areas over the large scale, this sledge-hammer approach ignores the inherent heterogeneity in the catchment. Societal (and policy) decisions involve more than abiotic quantification of water storage and flow. A more encompassing ecohydrological view facilitates a more rounded policy framework that has flexibility to accommodate multiple social drivers, and one that can accommodate an "ecosystem improvement" rather than single species improvement. Not every spot in the landscape is equally valuable for specific societal values. Areas of high activity may provide the resilience capacity necessary to prevent catastrophic changes. In times of ecological instability, ecosystem resilience is of paramount importance in maintaining essential ecosystem services. Hot spots of biogeochemical cycling will occur where unique situations arise, such as areas of surface and groundwater interaction, creating spots of localized, high activity. In order to understand the systems' potential to support various habitat niches in the large scale, the identification of specific hot spots or hot moments is necessary. A basal understanding of the concurrent biogeochemical cycles enables

  20. Groundwater Head Control of Catchment Nitrate Export

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. Catchment rehabilitation and hydro-geomorphic characteristics of mountain streams in the western Rift Valley escarpment of Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Ghebreyohannes Asfaha, Tesfaalem; Frankl, Amaury; Haile, Mitiku; Nyssen, Jan

    2013-04-01

    The catchments in the western Rift Valley escarpment of Northern Ethiopia are highly responsive in terms of hydro-geomorphic changes. With rapid deforestation in the first half of the 20th century, dense gully and scar networks developed, exporting huge amounts of runoff and sediment down to the fertile and densely populated Raya Valley. Consequently, threatening the environment and the livelihoods of the people both in the upstream and downstream areas. To reverse this problem, catchment-scale rehabilitation activities were initiated in the mid-1980s. In this study, we examine the hydro-geomorphic response of streams after catchment rehabilitation. Scar density was digitized from Google Earth imagery (2005) in 20 adjacent catchments and was explained in terms of its corresponding Normalized Difference Vegetation Index (NDVI) and slope gradient. This was accompanied by analysis of incidental repeat photographs and field observations. As evidenced by the series of repeat photographs, the vegetation cover of the catchments decreased up to 1975 and rapid reforestation occurred thereafter. A multiple regression analysis (R2=0.53, P<0.01) showed that scar density is negatively correlated with NDVI and positively with average gradient of very steep slopes (>60%). Moreover, due to reduction in discharge and sediment flow from the rehabilitated catchments, stream adjustments were observed in the field: previously braided stream channels have changed to single-thread streams, many lateral bars are stabilized and covered by vegetation, stream channels are incising due to clear water effect and the size of boulder deposits decreases. Therefore, the study shows that, land degradation activities in the upper catchments resulted in changes in hydro-geomorphic characteristics of the streams and reduction in runoff and sediment transport to the Raya Valley. Key words: scar density; NDVI; stream incision; soil and water conservation; stream adjustment; land use change.

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

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Weiler, Markus; Saroos, Manuel

    2013-04-01

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

  3. Minimizing uncertainty of daily rainfall interpolation over large catchments through realistic sampling of anisotropic correlogram parameters

    NASA Astrophysics Data System (ADS)

    Gyasi-Agyei, Yeboah

    2016-04-01

    It has been established that daily rainfall gauged network density is not adequate for the level of hydrological modelling required of large catchments involving pollutant and sediment transport, such as the catchments draining the coastal regions of Queensland, Australia, to the sensitive Great Barrier Reef. This paper seeks to establish a link between the spatial structure of radar and gauge rainfall for improved interpolation of the limited gauged data over a grid or functional units of catchments in regions with or without radar records. The study area is within Mt. Stapylton weather radar station range, a 128 km square region for calibration and validation, and the Brisbane river catchment for validation only. Two time periods (2000-01-01 to 2008-12-31 and 2009-01-01 to 2015-06-30) were considered, the later period for calibration when radar records were available and both time periods for validation without regard to radar information. Anisotropic correlograms of both the gauged and radar data were developed and used to establish the linkage required for areas without radar records. The maximum daily temperature significantly influenced the distributional parameters of the linkage. While the gauged, radar and sampled correlogram parameters reproduced the mean estimates similarly using leave-one-out cross-validation of Ordinary Kriging, the gauged parameters overestimated the standard deviation (SD) which reflects uncertainty by over 91% of cases compared with the radar or the sampled parameter sets. However, the distribution of the SD generated by the radar and the sampled correlogram parameters could not be distinguished, with a Kolmogorov-Smirnov test p-value of 0.52. For the validation case with the catchment, the percentage overestimation of SD by the gauged parameter sets decreased to 81.2% and 87.1% for the earlier and later time periods, respectively. It is observed that the extreme wet days' parameters and statistics were fairly widely distributed

  4. High-resolution seismic monitoring of geomorphic activity in a catchment

    NASA Astrophysics Data System (ADS)

    Burtin, A.; Hovius, N.; Turowski, J.; McArdell, B.; Vergne, J.

    2012-04-01

    Continuous survey of the surface activity in a river catchment is essential for the understanding of the landscape dynamics. In steep mountain catchments, a detailed spatial and temporal monitoring of geomorphic processes is generally impossible. The classic techniques (imagery and in situ channel approaches) are not adapted to the extreme conditions that occur during strong rainstorms. There is a real need to develop a method and to define the procedures that will allow the study of surface processes without any environmental dependency. Nowadays, more and more studies explore the use of the seismic instruments to survey the catchment activity. Seismometers can be deployed in sheltered area, which allow us to record in continuous the ground vibrations induced by surface processes, like the sediment transport and mass movements. To continue the exploration of this potential, we deployed a dense array of 10 seismometers in the Illgraben, a 10-km2 catchment in the Swiss Alps, during the summer 2011. This catchment is highly prone to hillslope and debris flow activity, so almost every summer convective storms trigger geomorphic events. The network was designed to monitor the spatial and temporal features of every type of surface activity. Thus during rainstorms, the stations located along the main stream well record the channel activity like the passage of sediment flows, while the instruments installed around the catchment reveal the occurrences of many rockfalls. These latter events show a spectral seismic signature at high frequencies (> 1 Hz), whereas the channel activity is dominant between 10 and 30 Hz. For the largest debris flow of the summer, we are able to identify the location of its initiation from the hillslope. Then, we can map the secondary events, which were triggered by the propagation of the debris flow. With these preliminary results, we demonstrate that the use of a dense seismic array is relevant to map in real time the landscape dynamics at the

  5. 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.

  6. Similarity and scale in catchment storm response

    NASA Technical Reports Server (NTRS)

    Wood, Eric F.; Sivapalan, Murugesu; Beven, Keith

    1993-01-01

    Until recently, very little progress had been made in understanding the relationship between small-scale variability of topography, soil, and rainfalls and the storm response seen at the catchment scale. The work reviewed here represents the first attempt at a systematic theoretical framework for such understanding in the context of surface runoff generation by different processes. The parameterization of hydrological processes over a range of scales is examined, and the concept of the 'representative elementary area' (REA) is introduced. The REA is a fundamental scale for catchment modeling at which continuum assumptions can be applied for the spatially variable controls and parameters, and spatial patterns no longer have to be considered explicitly. The investigation of scale leads into the concept of hydrologic similarity in which the effects of the environmental controls on runoff generation and flood frequency response be investigated independently of catchment scale. The paper reviews the authors' initial results and hopefully will motivate others to also investigate the issues of hydrologic scale and similarity.

  7. Picturing and modeling catchments by representative hillslopes

    NASA Astrophysics Data System (ADS)

    Loritz, Ralf; Hassler, Sibylle K.; Jackisch, Conrad; Allroggen, Niklas; van Schaik, Loes; Wienhöfer, Jan; Zehe, Erwin

    2017-03-01

    This study explores the suitability of a single hillslope as a parsimonious representation of a catchment in a physically based model. We test this hypothesis by picturing two distinctly different catchments in perceptual models and translating these pictures into parametric setups of 2-D physically based hillslope models. The model parametrizations are based on a comprehensive field data set, expert knowledge and process-based reasoning. Evaluation against streamflow data highlights that both models predicted the annual pattern of streamflow generation as well as the hydrographs acceptably. However, a look beyond performance measures revealed deficiencies in streamflow simulations during the summer season and during individual rainfall-runoff events as well as a mismatch between observed and simulated soil water dynamics. Some of these shortcomings can be related to our perception of the systems and to the chosen hydrological model, while others point to limitations of the representative hillslope concept itself. Nevertheless, our results confirm that representative hillslope models are a suitable tool to assess the importance of different data sources as well as to challenge our perception of the dominant hydrological processes we want to represent therein. Consequently, these models are a promising step forward in the search for the optimal representation of catchments in physically based models.

  8. Water quality in sugar catchments of Queensland.

    PubMed

    Rayment, G E

    2003-01-01

    Water quality condition and trend are important indicators of the impact of land use on the environment, as degraded water quality causes unwelcome changes to ecosystem composition and health. These concerns extend to the sea, where discharges of nutrients, sediments and toxicants above natural levels are unwelcome, particularly when they drain to the Great Barrier Reef World Heritage Area and other coastal waters of Queensland. Sugarcane is grown in 26 major river catchments in Queensland, most in environmentally sensitive areas. This puts pressure on the Queensland Sugar Industry to manage the land in ways that have minimum adverse off-site impacts. Sugar researchers including CRC Sugar have been associated with water quality studies in North Queensland. These include investigations and reviews to assess the role of groundwater as a pathway for nitrate loss from canelands in the Herbert Catchment, to find causes of oxygen depletion in water (including irrigation runoff) from Ingham to Mackay, to use residues of superseded pesticides as indicators of sediment loss to the sea, and to assemble information on water quality pressure and status in sugar catchments. Key findings, plus information on input pressures are described in this paper, and areas of concern and opportunities discussed.

  9. Modeling of facade leaching in urban catchments

    NASA Astrophysics Data System (ADS)

    Coutu, S.; Del Giudice, D.; Rossi, L.; Barry, D. A.

    2012-12-01

    Building facades are protected from microbial attack by incorporation of biocides within them. Flow over facades leaches these biocides and transports them to the urban environment. A parsimonious water quantity/quality model applicable for engineered urban watersheds was developed to compute biocide release from facades and their transport at the urban basin scale. The model couples two lumped submodels applicable at the basin scale, and a local model of biocide leaching at the facade scale. For the facade leaching, an existing model applicable at the individual wall scale was utilized. The two lumped models describe urban hydrodynamics and leachate transport. The integrated model allows prediction of biocide concentrations in urban rivers. It was applied to a 15 km2urban hydrosystem in western Switzerland, the Vuachère river basin, to study three facade biocides (terbutryn, carbendazim, diuron). The water quality simulated by the model matched well most of the pollutographs at the outlet of the Vuachère watershed. The model was then used to estimate possible ecotoxicological impacts of facade leachates. To this end, exceedance probabilities and cumulative pollutant loads from the catchment were estimated. Results showed that the considered biocides rarely exceeded the relevant predicted no-effect concentrations for the riverine system. Despite the heterogeneities and complexity of (engineered) urban catchments, the model application demonstrated that a computationally "light" model can be employed to simulate the hydrograph and pollutograph response within them. It thus allows catchment-scale assessment of the potential ecotoxicological impact of biocides on receiving waters.

  10. Land use control of nitrate export behavior across catchments

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Nutrient exports from catchments and their temporal and spatial variability significantly affect downstream water quality and ecosystem health. There is hence a need to better understand and classify catchment nutrient export dynamics in order to reproduce catchment functions (such as nutrient mobilization and retention) and predict the response of these functions to changing boundary conditions. However, the complexity of catchment structure and the multitude of the processes involved challenge this objective. One approach to meet this challenge is a top-down, data-driven analysis of integrated catchment responses, such as discharge and solute concentration time series. For top-down analysis, different catchments are compared to identify key variables governing catchment response. We conducted a multi-catchment study applying top-down methods to analyze nitrate concentration and discharge time series from streams draining nine catchments in central Germany. The studied catchments, ranging from "pristine" mountains to agriculturally-managed lowlands, span gradients in land use, geology, and climatic conditions. We hypothesized that land use type is the main control on stream nitrate concentrations and catchment export behaviour, with more chemostatic export behaviour occurring in catchments with higher percentages of agricultural land use due to the presence of large nitrate stocks that effectively function as an unlimited nitrate storage. Consistent with this hypothesis we found that median nitrate concentrations were positively correlated with the percentage of agricultural land use in the different catchments despite differences in catchment climatic and geological conditions. Magnitude and direction of concentration-discharge relationship was evaluated using the slope b of the linear regression of log nitrate concentrations vs. log discharge as a metric for export behaviour. All catchments exhibited a positive slope b indicating concentrations increase with

  11. Problems with the interpolation of precipitation amounts in mountainous catchments using traditional techniques

    NASA Astrophysics Data System (ADS)

    Soto-Sandoval, J. C.; Jacquin, A. P.

    2012-04-01

    Spatial distribution of precipitation is a major source of predictive uncertainty in hydrological modeling, especially in catchments characterized by a complex topography. In this case, traditional methods utilized in hydrology are most probably unable to provide reliable estimations of precipitation amounts corresponding to different elevations. However, the simplicity and ease of application of such methods maintain them as attractive alternatives for engineering practitioners. This study is intended to evaluate to what extent precipitation estimates provided by traditional methods are appropriate in the case of Andean catchments. The catchment case study is Aconcagua River at Chacabuquito, located in the Andean region of Central Chile. This is a snowmelt dominated catchment with a surface of 2110[Km2], where approximately 5% corresponds to glaciers. Elevation ranges from 950[m.a.s.l.] to 5930[m.a.s.l.]. Most precipitation occurs between May and August, while precipitation amounts during the rest of the year are relatively low. The pluviometric network is extremely sparse. In this study, monthly data from nine precipitation stations in the period April 1965-March 2001 are used. All of these stations are located between 600[m.a.s.l.] and 3000[m.a.s.l.] and only four of them are actually within the catchment Precipitation interpolation techniques applied in this study include multiquadratic function (MF) fitting, Thiessen Polygons (TP) and inverse distance (ID) weighting. The goodness of fit of precipitation estimates is evaluated by means of cross validation experiments. Due to the limitations existing in the spatial extent of data, these experiments only provide information about the plausibility of the precipitation estimates below 3000[m.a.s.l.], where about 62% of the catchment area is located. Results reveal that estimation errors are significant for all methods, especially during the humid season. Throughout the hydrological year, the MF method provides the

  12. Understanding sediment sources in a peri-urban Mediterranean catchment using geochemical tracers

    NASA Astrophysics Data System (ADS)

    Ferreira, Carla; Walsh, Rory; Kikuchi, Ryunosuke; Blake, Will

    2016-04-01

    different particle size fractions (0.125-2.000mm, 0.063-0.125mm and <0.063mm). Seventeen stream sites were sampled plus a sample of sediment from a road surface immediately it entered the stream network. The elemental composition (40 elements) of each size fraction was assessed using a Niton X-ray fluorescence elemental analyser. Results show that rock type has a profound influence on the geochemical properties of bed-sediments. Catchment outlet sediment collected after the summer and a storm of high rainfall intensity following dry weather displayed geochemical properties closer to those of sediment from sandstone sub-catchments, and in particularly sediment from the enterprise park under construction. After the storm that followed very wet weather, however, limestone areas became of much greater significance as sediment sources, probably because of the high soil saturation. At limestone stream sites receiving runoff from the newly constructed road, fine bed-sediment geochemistry was found to be similar to that of road sediment, indicating a high contribution of this source. These results are supported by spatio-temporal differences in streamflow and suspended sediment concentrations at instrumented monitoring stations. It is concluded that this methodology represents a potentially useful tool to enable river managers to detect and assess sediment sources in urbanized and partly urbanized catchments, and to supporting them in designing and implementing effective land-use mosaics and site-specific measures to mitigate erosion.

  13. Catchment classification and similarity using correlation in streamflow time series

    NASA Astrophysics Data System (ADS)

    Fleming, B.; Archfield, S. A.

    2012-12-01

    Catchment classification is an important component of hydrologic analyses, particularly for linking changes in ecological integrity to streamflow alteration, transferring time series or model parameters from gauged to ungauged locations, and as a way to understand the similarity in the response of catchments to change. Metrics of similarity used in catchment classification have ranged from aggregate catchment properties such as geologic or climate characteristics to variables derived from the daily streamflow hydrograph; however, no one set of classification variables can fully describe similarity between catchments as the variables used for such assessments often depend on the question being asked. We propose an alternative method based on similarity for hydrologic classification: correlation between the daily streamflow time series. If one assumes that the streamflow signal is the integrated response of a catchment to both climate and geology, then the strength of correlation in streamflow between two catchments is a measure of the strength of similarity in hydrologic response between those two catchments. Using the nonparametric Spearman rho correlation coefficient between streamflow time series at 54 unregulated and unaltered streamgauges in the mid-Atlantic United States, we show that correlation is a parsimonious classification metric that results in physically interpretable classes. Using the correlation between the deseasonalized streamflow time series and reclassifying the streamgauges, we also find that seasonality plays an important role in understanding catchment flow dynamics, especially those that can be linked to ecological response and similarity although not to a large extent in this study area.

  14. Catchment-scale evaluation of pollution potential of urban snow at two residential catchments in southern Finland.

    PubMed

    Sillanpää, Nora; Koivusalo, Harri

    2013-01-01

    Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with continuous runoff measurements. The results of the snow quality were used to produce catchment-scale estimates of areal snow mass loads (SML). Based on the results, urbanization reduced areal snow water equivalent but increased pollutant accumulation in snow: SMLs in a medium-density residential catchment were two- to four-fold higher in comparison with a low-density residential catchment. The main sources of pollutants were related to vehicular traffic and road maintenance, but also pet excrement increased concentrations to a high level. Ploughed snow can contain 50% of the areal pollutant mass stored in snow despite its small surface area within a catchment.

  15. Modelling overbank flow on farmed catchments taking into account spatial hydrological discontinuities

    NASA Astrophysics Data System (ADS)

    Moussa, R.; Tilma, M.; Chahinian, N.; Huttel, O.

    2003-04-01

    In agricultural catchments, hydrological processes are largely variable in space due to human impact causing hydrological discontinuities such as ditch network, field limits and terraces. The ditch network accelerates runoff by concentrating flows, drains the water table or replenishes it by reinfiltration of the runoff water. During extreme flood events, overbank flow occurs and surface pathflows are modified. The purpose of this study is to assess the influence of overbank flow on hydrograph shape during flood events. For that, MHYDAS, a physically based distributed hydrological model, was especially developed to take into account these hydrological discontinuities. The model considers the catchment as a series of interconnected hydrological unit. Runoff from each unit is estimated using a deterministic model based on the pounding-time algorithm and then routed through the ditch network using the diffusive wave equation. Overbank flow is modelled by modifying links between the hydrological units and the ditch network. The model was applied to simulate the main hydrological processes on a small headwater farmed Mediterranean catchment located in Southern France. The basic hydrometeorological equipment consists of a meteorological station, rain gauges, a tensio-neutronic and a piezometric measurement network, and eight water flow measurements. A multi-criteria and multi-scale approach was used. Three independent error criteria (Nash, error on volume and error on peak flow) were calculated and combined using the Pareto technique. Then, a multi-scale approach was used to calibrate and validate the model for the eight water flow measurements. The application of MHYDAS on the extreme ten flood events of the last decade enables to identify the ditches where overbank flows occur and to calculate discharge at various points of the ditch network. Results show that for the extreme flood event, more than 45% of surface runoff occur due to overbank flow. Discussion shows that

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  17. Extreme Rainfall Impacts in Fractured Permeable Catchments

    NASA Astrophysics Data System (ADS)

    Ireson, A. M.; Butler, A. P.

    2009-12-01

    Serious groundwater flooding events have occurred on Chalk catchments in both the UK and north west Europe in the last decade, causing substantial amounts of disruption and economic damage. These fractured, permeable catchments are characterized by low surface runoff, high baseflow indices and strongly attenuated streamflow hydrographs. They have a general resilience to drought and pluvial/fluvial flooding. The small pore size of the Chalk matrix (~ 1 µm) exerts a high suction, such that dynamic storage is primarily due to the fractures, and amounts to ~ 1% of the total volume. As a result, under sustained rainfall the water table can rise up to exceptional levels leading to surface water emergence from springs and valleys. Floodwater may slowly drain with the topography, or, in localized depressions, it may simply pond until the groundwater levels decline. In winter 2000/1, a sequence of individually unexceptional rainfall events over several months led to large scale flooding in the Pang catchment, Berkshire, UK. By contrast, an extreme rainfall event on 20th July 2007 in the same catchment caused a very rapid response at the water table, but due to the antecedent conditions did not lead to flooding. The objective of this study is to quantify how the water table in a fractured permeable catchment responds to different types of rainfall, and the implications of this for groundwater flooding. We make use of measurements from the Pang catchment, including: rainfall (tipping bucket gauges); actual evaporation (eddy flux correlation); soil water content (profile probes and neutron probes); near surface matric potential (tensiometers and equitensiometers); deep (>10m) matric potential (deep jacking tensiometers); and water table elevation (piezometers). Conventional treatment of recharge in Chalk aquifers considers a fixed bypass component of rainfall, normally 15%, to account for the role of the fractures. However, interpretation of the field data suggest three modes

  18. Modeling relationships between catchment attributes and river water quality in southern catchments of the Caspian Sea.

    PubMed

    Hasani Sangani, Mohammad; Jabbarian Amiri, Bahman; Alizadeh Shabani, Afshin; Sakieh, Yousef; Ashrafi, Sohrab

    2015-04-01

    Increasing land utilization through diverse forms of human activities, such as agriculture, forestry, urban growth, and industrial development, has led to negative impacts on the water quality of rivers. To find out how catchment attributes, such as land use, hydrologic soil groups, and lithology, can affect water quality variables (Ca(2+), Mg(2+), Na(+), Cl(-), HCO 3 (-) , pH, TDS, EC, SAR), a spatio-statistical approach was applied to 23 catchments in southern basins of the Caspian Sea. All input data layers (digital maps of land use, soil, and lithology) were prepared using geographic information system (GIS) and spatial analysis. Relationships between water quality variables and catchment attributes were then examined by Spearman rank correlation tests and multiple linear regression. Stepwise approach-based multiple linear regressions were developed to examine the relationship between catchment attributes and water quality variables. The areas (%) of marl, tuff, or diorite, as well as those of good-quality rangeland and bare land had negative effects on all water quality variables, while those of basalt, forest land cover were found to contribute to improved river water quality. Moreover, lithological variables showed the greatest most potential for predicting the mean concentration values of water quality variables, and noting that measure of EC and TDS have inversely associated with area (%) of urban land use.

  19. Lithogenic and cosmogenic tracers in catchment hydrology

    SciTech Connect

    Nimz, G.J.

    1995-01-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water, which is one of the primary concerns in hydrology. Many groundwater solutes are derived as a result of interaction between the water and the rock and/or soil within the system. These are termed {open_quotes}lithogenic{close_quotes} solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both internally and externally to the catchment system. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing {open_quotes}cosmogenic{close_quotes} nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing {open_quotes}thermonuclear{close_quotes} nuclides), or radioactive and fission decay of naturally-occurring elements, such as U and Th (producing {open_quotes}in-situ{close_quotes} lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading {open_quotes}cosmogenic nuclides{close_quotes}, and for simplicity we will often follow that usage, although always clearly indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute compositions in groundwater, and how these compositions can therefore be used in integrative ways to understand the physical history of groundwater within a catchment system.

  20. Evaluation of TOPLATS on three Mediterranean catchments

    NASA Astrophysics Data System (ADS)

    Loizu, Javier; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel

    2016-08-01

    Physically based hydrological models are complex tools that provide a complete description of the different processes occurring on a catchment. The TOPMODEL-based Land-Atmosphere Transfer Scheme (TOPLATS) simulates water and energy balances at different time steps, in both lumped and distributed modes. In order to gain insight on the behavior of TOPLATS and its applicability in different conditions a detailed evaluation needs to be carried out. This study aimed to develop a complete evaluation of TOPLATS including: (1) a detailed review of previous research works using this model; (2) a sensitivity analysis (SA) of the model with two contrasted methods (Morris and Sobol) of different complexity; (3) a 4-step calibration strategy based on a multi-start Powell optimization algorithm; and (4) an analysis of the influence of simulation time step (hourly vs. daily). The model was applied on three catchments of varying size (La Tejeria, Cidacos and Arga), located in Navarre (Northern Spain), and characterized by different levels of Mediterranean climate influence. Both Morris and Sobol methods showed very similar results that identified Brooks-Corey Pore Size distribution Index (B), Bubbling pressure (ψc) and Hydraulic conductivity decay (f) as the three overall most influential parameters in TOPLATS. After calibration and validation, adequate streamflow simulations were obtained in the two wettest catchments, but the driest (Cidacos) gave poor results in validation, due to the large climatic variability between calibration and validation periods. To overcome this issue, an alternative random and discontinuous method of cal/val period selection was implemented, improving model results.

  1. Resilience of catchment sediment yield to climate perturbations

    NASA Astrophysics Data System (ADS)

    Van De Wiel, Marco; Lipkowski, Emily

    2015-04-01

    It is commonly thought that catchment sediment yield is largely governed by allogenic controls acting on the catchment. Under this paradigm, variations in climatic, tectonic or anthropogenic forcing are directly transmitted to the catchment sediment yield. The sediment yield thus represents a temporal signature of the governing external forces. This paradigm, however, has been challenged by recent research, which has shown that autogenic controls from within the catchment can significantly affect and, in some cases, overwrite the allogenic signal in the sediment yield signal. In these cases the catchment sediment yield can be considered to be resilient to external perturbation. On the other hand, it also has been shown that, in some other cases, the allogenic signal can indeed be transmitted efficiently through the catchment, without too much distortion by the autogenic controls. In these latter cases, the sediment yield signal, and hence the downstream sediment deposits, can be a reliable archive of past environmental forcing. This study uses computer simulation to investigate the autogenic resilience of catchment sediment yields. Specifically, it investigates allogenic signal preservation in catchment sediment yield in the context of climate signals. It is hypothesized that 1) the resilience of the catchment sediment yield signal is largely determined by the catchment's spatial heterogeneity (of topography, vegetation, soil properties, ...) and the external signal's temporal heterogeneity and amplitude; and 2) catchment resilience is inversely correlated with spatial heterogeneity and positively correlated with the temporal heterogeneity and amplitude of the allogenic signal. This hypothesis is tested using a set of similar catchments, but with different relief ranges, different levels of topographic smoothness, different sediment distributions, and different artificial vegetation covers. These catchments are subjected to a range of rainfall scenarios over a 300

  2. Validation of Pacific Northwest Hydrologic Landscapes at the Catchment Scale

    NASA Astrophysics Data System (ADS)

    Sawicz, K. A.; Leibowitz, S. G.; Comeleo, R. L.; Wigington, P. J., Jr.

    2014-12-01

    The interaction between the physical properties of a catchment (form) and climatic forcing of precipitation and energy control how water is partitioned, stored, and conveyed through a catchment (function). Hydrologic Landscapes (HLs) were previously developed across Oregon and describe climatic and physical properties for over 5000 assessment units. This approach was then extended to the three Pacific Northwest states of Washington, Oregon and Idaho (PNW HL). The HLs were developed using the National Hydrography Dataset's WBD HU12 scale and are comprised of classification components describing climate, climate seasonality, aquifer permeability, terrain, and soil permeability. To compare the PNW HL classification to catchment hydrologic behavior, HLs were aggregated to catchment scale to compare against the input/output of water in the catchment. HL aggregation must preserve information on the location of the HL within the catchment outlet (upstream vs. downstream) and properties of that HL (i.e. water source vs. sink). Catchment function was investigated by use of hydrologic signatures, which are attributes of long-term time series of water into and out of the catchment. Signatures include Runoff Ratio, Baseflow Index, Snow Ratio, and Recession Coefficients. This study has three primary objectives: 1) derivation of hydrologic signatures to capture the hydrologic behavior for catchments in the Pacific Northwest: 2) development of methodology to aggregate HLs to the catchment scale; and 3) statistical analysis of signature values and trends with respect to aggregated HL classification. We hypothesize that we will find: 1) strong relationships between aggregated HLs and hydrologic signatures; 2) signatures related to water balance are explained by climatic conditions; and 3) signatures describing flow paths are predicted by terrain, soil, and aquifer permeability. This study examined 230 catchments to achieve objectives and test hypotheses stated.

  3. Which spatial discretization for distributed hydrological models? Proposition of a methodology and illustration for medium to large-scale catchments

    NASA Astrophysics Data System (ADS)

    Dehotin, J.; Braud, I.

    2008-05-01

    Distributed hydrological models are valuable tools to derive distributed estimation of water balance components or to study the impact of land-use or climate change on water resources and water quality. In these models, the choice of an appropriate spatial discretization is a crucial issue. It is obviously linked to the available data, their spatial resolution and the dominant hydrological processes. For a given catchment and a given data set, the "optimal" spatial discretization should be adapted to the modelling objectives, as the latter determine the dominant hydrological processes considered in the modelling. For small catchments, landscape heterogeneity can be represented explicitly, whereas for large catchments such fine representation is not feasible and simplification is needed. The question is thus: is it possible to design a flexible methodology to represent landscape heterogeneity efficiently, according to the problem to be solved? This methodology should allow a controlled and objective trade-off between available data, the scale of the dominant water cycle components and the modelling objectives. In this paper, we propose a general methodology for such catchment discretization. It is based on the use of nested discretizations. The first level of discretization is composed of the sub-catchments, organised by the river network topology. The sub-catchment variability can be described using a second level of discretizations, which is called hydro-landscape units. This level of discretization is only performed if it is consistent with the modelling objectives, the active hydrological processes and data availability. The hydro-landscapes take into account different geophysical factors such as topography, land-use, pedology, but also suitable hydrological discontinuities such as ditches, hedges, dams, etc. For numerical reasons these hydro-landscapes can be further subdivided into smaller elements that will constitute the modelling units (third level of

  4. A numerical solution to define channel heads and hillslope parameters from digital topography of glacially conditioned catchments

    NASA Astrophysics Data System (ADS)

    Salcher, Bernhard; Baumann, Sebastian; Kober, Florian; Robl, Jörg; Heiniger, Lukas

    2016-04-01

    The analysis of the slope-area relationship in bedrock streams is a common way for discriminating the channel from the hillslope domain and associated landscape processes. Spatial variations of these domains are important indicators of landscape change. In fluvial catchments, this relationship is a function of contributing drainage area, channel slope and the threshold drainage area for fluvial erosion. The resulting pattern is related to climate, tectonic and underlying bedrock. These factors may become secondary in catchments affected by glacial erosion, as it is the case in many mid- to high-latitude mountain belts. The perturbation (i.e. the destruction) of an initial steady state fluvial bedrock morphology (where uplift is balanced by surface lowering rates) will tend to become successively larger if the repeated action of glacial processes exceeds the potential of fluvial readjustment during deglaciated periods. Topographic change is associated with a decrease and fragmentation of the channel network and an extension of the hillslope domain. In case of glacially conditioned catchments discrimination of the two domains remains problematic and a discrimination inconsistent. A definition is therefore highly needed considering that (i) a spatial shift in the domains affect the process and rate of erosion and (ii) topographic classifications of alpine catchments often base on channel and hillslope parameters (i.e.channel or hillslope relief). Here we propose a novel numerical approach to topographically define channel heads from digital topography in glacially conditioned mountain range catchments in order to discriminate the channel from the hillslope domain. We analyzed the topography of the southern European Central Alps, a region which (i) has been glaciated multiple times during the Quaternary, shows (ii) little lithological variations, is (iii) home of very low erodible rocks and is (iv) known as a region were tectonic processes have largely ceased. The

  5. Human-Landscape interaction in cultivated lowland catchments (Louroux catchment, Loire Valley, France)

    NASA Astrophysics Data System (ADS)

    Cerdan, Olivier; Foucher, Anthony; Gay, Aurore; Salvador Blanes, Sébastien; Evrard, Olivier; Desmet, Marc

    2015-04-01

    Change of land use or agricultural practices are known to have high impacts on sediment transfer in catchments and rivers. Numerous studies have particularly illustrated these effects in sloping land in tropical areas undergoing deforestation. Much less attention has been paid to lowland humid areas, where permanent land uses have been plowed more recently. However recent studies reported significant erosion rates in these environments despite the gentle topography and the temperate climate. In order to quantify these changing fluxes of sediment, several instrumentation and historical database analyses were carried out in various catchments of the Loire Valley, France. More particularly, a multiparameter analysis was conducted on sedimentary deposits of a pond created in the 11th century in a catchment representative of cultivated and drained lowland environments where an intensification of agricultural practices has occurred during the last 60 years. The results showed that the initial land consolidation period (1954-1960) was characterized by a dominance of allochtonous material input to the pond. This input represents an erosion of 1900 to 2300 t.km-².yr-1 originating from the catchment. Then, between 1970-1990, terrigenous material flow decreased progressively and tended to stabilize, whereas eutrophication and associated primary production increased in the pond. In addition to these temporal changes, material input across the pond during the last 10 years corresponds to a loss of material in the catchment ranging between 90 and 102 t.km-2.yr-1. While a strong decrease is observed, it still represents a 60-fold increase of the sediment fluxes to the pond compared to the preintensification period. Subsequent research monitoring studies permitted to differentiate between the different sources of sediment and highlight the importance of surface erosion during flood events and of bank erosion during low flows. The increased export of the sediment is primarily due

  6. Topological and canonical kriging for design flood prediction in ungauged catchments: an improvement over a traditional regional regression approach?

    USGS Publications Warehouse

    Archfield, Stacey A.; Pugliese, Alessio; Castellarin, Attilio; Skøien, Jon O.; Kiang, Julie E.

    2013-01-01

    In the United States, estimation of flood frequency quantiles at ungauged locations has been largely based on regional regression techniques that relate measurable catchment descriptors to flood quantiles. More recently, spatial interpolation techniques of point data have been shown to be effective for predicting streamflow statistics (i.e., flood flows and low-flow indices) in ungauged catchments. Literature reports successful applications of two techniques, canonical kriging, CK (or physiographical-space-based interpolation, PSBI), and topological kriging, TK (or top-kriging). CK performs the spatial interpolation of the streamflow statistic of interest in the two-dimensional space of catchment descriptors. TK predicts the streamflow statistic along river networks taking both the catchment area and nested nature of catchments into account. It is of interest to understand how these spatial interpolation methods compare with generalized least squares (GLS) regression, one of the most common approaches to estimate flood quantiles at ungauged locations. By means of a leave-one-out cross-validation procedure, the performance of CK and TK was compared to GLS regression equations developed for the prediction of 10, 50, 100 and 500 yr floods for 61 streamgauges in the southeast United States. TK substantially outperforms GLS and CK for the study area, particularly for large catchments. The performance of TK over GLS highlights an important distinction between the treatments of spatial correlation when using regression-based or spatial interpolation methods to estimate flood quantiles at ungauged locations. The analysis also shows that coupling TK with CK slightly improves the performance of TK; however, the improvement is marginal when compared to the improvement in performance over GLS.

  7. Effects of impervious pavements on reducing runoff in an arid urban catchment

    NASA Astrophysics Data System (ADS)

    Epshtein, O.; Turnbull, L.; Earl, S.

    2011-12-01

    from 5 mm to 25 mm. Model testing shows total event discharge simulated well, although low Nash-Sutcliffe coefficients for events indicate a poor fit between the shape and timing of the modeled and monitored hydrograph, which we attribute to poor characterization of friction factors in urban catchments. Scenario-based model analysis tested catchment response to substitution of pervious for conventional pavement by percent and pavement-function scenarios. Results are consistent with previous findings in that short duration-high intensity storms trigger threshold infiltration capacity, past which pervious pavement damping of runoff volume levels off, approaching conventional levels. However at the modeled catchment scale, this initial damping represents a significant reduction in volume, peak flow velocity, and contaminant loading potential. Urban surface drainage networks concentrate and channel flow along roads: the capacity of pervious pavements to simultaneously increase infiltration directly at location of greatest runoff and mitigate inflow effects from remote points has compelling potential as a hydrologic and urban systems engineering tool.

  8. 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

  9. Catchment Restoration in the Tweed UNESCO-IHP HELP Basin - Eddleston Water

    NASA Astrophysics Data System (ADS)

    Spray, Christopher

    2013-04-01

    initial characterisation of the catchment; the identification of potential key locations and types of intervention to improve ecological status and flood risk reduction; the setting up of the monitoring networks, the engagement with local communities and land managers; initial habitat modifications and the early results of the study. We situate this within the wider context of priorities for restoration and the UNESCO IHP-HELP programme.

  10. A simple linear catchment-response model for investigating sediment efflux associated with climate and land use change in Goodwin Creek, MS

    NASA Astrophysics Data System (ADS)

    Aubeneau, A. F.; Thompson, S. E.; Hassan, M. A.; Packman, A. I.

    2009-12-01

    Erosion and sediment transport are influenced by hydrological regime (rainfall-runoff), catchment properties (vegetation, topography, soil properties), management practices (land use), and their interactions. Here, we use a simple linear catchment response model to describe sediment transport in the Goodwin Creek catchment. The model includes two linear stores, one for the hillslope and one for the fluvial network. The hillslope store is supplied with sediments from upland erosion, with event-driven mobilization occurring over the effective duration of each storm. Some of the mobilized sediments are redeposited on the hillslope and the remainder is transferred to the river network. Additional sediment supply to the network occurs from the channel via bank erosion. Suspended sediment transport and deposition are considered along river channels in order to determine the timing and magnitude of sediment efflux from the catchment. In environments dominated by hillslope erosion, sediment delivery ratio (the ratio between upland erosion and sediment yield at the outlet) is expected to be closely related to catchment hydrological response. However, fluvial storage obscures this relationship by modulating the morphodynamic response to primary hydrological and geomorphological drivers. We used the model to distinguish the relative influence of climate forcing, hydrological response and land use practices on sediment transport and delivery in the Goodwin Creek catchment, where sediment and channel dynamics have been monitored in fourteen sub-catchments for over twenty years. These sub-catchments include a range of channel sizes and a diversity of management practices over the length of the data record. Our results suggest that hillslope processes dominate the delivery ratio in smaller catchments but that channel processes become more important at larger spatial scales. Furthermore, although climate variability could explain a large proportion of the variability in sediment

  11. Generality of Fractal 1/f Scaling in Catchment Tracer Time Series: Implications for Catchment Travel Time Distributions

    NASA Astrophysics Data System (ADS)

    Godsey, S. E.; Palucis, M. C.; Kirchner, J. W.

    2007-12-01

    The mean travel time - the time that it takes a parcel of rainwater to reach the stream - is a basic parameter used to characterize catchments. More generally, a catchment is characterized by its travel-time distribution, which is described not only by its mean but also its shape. The travel time distribution of water in a catchment is typically inferred from passive tracer time series (typically water isotopes or chloride concentrations) in rainfall and streamflow. The catchment mixes precipitation inputs (and thus passive tracers) falling at different points in time; as a result, tracer fluctuations in streamflow are usually strongly damped relative to precipitation. Mathematically, this mixing of waters of different ages is represented by the convolution of the travel time distribution and the precipitation inputs to generate the stream outputs. Previous analyses of both rainfall and streamflow tracer time series from several catchments in Wales have demonstrated that rainfall chemistry spectra resemble white noise, whereas these same catchments exhibit fractal 1/f scaling in stream tracer chemistry over three orders of magnitude. These observations imply that these catchments have an approximate power-law distribution of travel times, and thus they retain a long memory of past inputs. The observed fractal scaling places strong constraints on possible models of catchment behavior: commonly-used exponential or advection-dispersion travel time distribution models do not exhibit fractal scaling. Here we test the generality of the observed fractal scaling of streamflow chemistry, by analyzing long-term tracer time series from 17 other catchments in North America and Europe. Special care is taken to account for the effects of spectral aliasing. We demonstrate that 1/f fractal scaling of stream chemistry is a common feature of these catchments and discuss the implications of this observation to catchment-scale hydrologic modeling. We then present the best-fit travel

  12. Standardised survey method for identifying catchment risks to water quality.

    PubMed

    Baker, D L; Ferguson, C M; Chier, P; Warnecke, M; Watkinson, A

    2016-06-01

    This paper describes the development and application of a systematic methodology to identify and quantify risks in drinking water and recreational catchments. The methodology assesses microbial and chemical contaminants from both diffuse and point sources within a catchment using Escherichia coli, protozoan pathogens and chemicals (including fuel and pesticides) as index contaminants. Hazard source information is gathered by a defined sanitary survey process involving use of a software tool which groups hazards into six types: sewage infrastructure, on-site sewage systems, industrial, stormwater, agriculture and recreational sites. The survey estimates the likelihood of the site affecting catchment water quality, and the potential consequences, enabling the calculation of risk for individual sites. These risks are integrated to calculate a cumulative risk for each sub-catchment and the whole catchment. The cumulative risks process accounts for the proportion of potential input sources surveyed and for transfer of contaminants from upstream to downstream sub-catchments. The output risk matrices show the relative risk sources for each of the index contaminants, highlighting those with the greatest impact on water quality at a sub-catchment and catchment level. Verification of the sanitary survey assessments and prioritisation is achieved by comparison with water quality data and microbial source tracking.

  13. An Eco-hydrologic Assessment of Small Experimental Catchments with Various Land Uses within the Panama Canal Watershed: Agua Salud Project

    NASA Astrophysics Data System (ADS)

    Crouch, T. D.; Ogden, F. L.; Stallard, R. F.; Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project

    2010-12-01

    Hydrological processes in the humid tropics are poorly understood and an important topic when it comes to water management in the seasonal tropics. The Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, seeks to understand these processes and quantify the long-term effects of different land cover and uses across the Panama Canal Watershed. One of the project’s main objectives is to understand how reforestation effects seasonal stream flows. To meet this objective, a baseline characterization of hydrology on the small catchment scale is being assessed across different land uses typical in rural Panama. The small experimental catchments are found within Panama’s protected Soberania National Park and the adjacent headwaters of the Agua Salud and Mendoza Rivers, all of which are part of the greater Panama Canal Watershed. The land uses being monitored include a variety of control catchments as well as treated pasture sites. The catchments used for this study include a mature old regrowth forest, a 50% deforested or mosaic regrowth site, an active pasture and a monoculture invasive grass site (saccharum spontaneum) as experimental controls and two treated catchments that were recently abandoned pastures converted to teak and native species timber plantations. Installed instrumentation includes a network of rain gauges, v-notched weirs, atmometers, an eddy covariance system and an assortment of meteorological and automated geochemical sampling systems. Spatial, rainfall, runoff and ET data across these six geologically and topographically similar catchments are available from 2009 and 2010. Classic water balance and paired catchment techniques were used to compare the catchments on an annual, seasonal, and event basis. This study sets the stage for hydrologic modeling and for better understanding the effects of vegetation and land-use history on rainfall-runoff processes for the Agua Salud Project and Panama Canal

  14. Optimization models for siting water quality monitoring stations in a catchment.

    PubMed

    Kao, Jehng-Jung; Li, Pei-Hao; Hu, Wen-Shin

    2012-01-01

    A water quality monitoring network (WQMN) must be designed so as to adequately protect the water quality in a catchment. Although a simulated annealing (SA) method was previously applied to design a WQMN, the SA method cannot ensure the solution it obtained is the global optimum. Therefore, two new linear optimization models are proposed in this study to minimize the deviation of the cost values expected to identify the possible pollution sources based on uniform cost (UC) and coverage elimination uniform cost (CEUC) schemes. The UC model determines the expected cost values by considering each sub-catchment being covered by which station, while the CEUC model determines the coverage of each station by eliminating the area covered by any upstream station. The proposed models are applied to the Derchi reservoir catchment in Taiwan. Results show that the global optimal WQMN can be effectively determined by using the UC or CEUC model, for which both results are better than those from the SA method, especially when the number of stations becomes large.

  15. Catchment Systems Engineering: A New Paradigm in Water Management

    NASA Astrophysics Data System (ADS)

    Quinn, P. F.; Wilkinson, M. E.; Burke, S.; O'Donnell, G. M.; Jonczyk, J.; Barber, N.; Nicholson, A.

    2012-04-01

    Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Catchment Systems Engineering seeks to describe catchment the function (or role) as the principal driver for evaluating how it should be managed in the future. Catchment Systems Engineering does not seek to re-establish a natural system but rather works with natural processes in order to engineer landscapes to accrue multiple benefits. The approach involves quantifying and assessing catchment change, impacts and most importantly, suggests an urgent and proactive agenda for future planning. In particular, an interventionist approach to managing hydrological flow pathways across scale is proposed. It is already accepted that future management will require a range of scientific expertise and full engagement with stakeholders. This inclusive concept under a Catchment Systems Engineering agenda forces any consortia to commit to actively changing and perturbing the catchment system and thus learn, in situ, how to manage the environment for collective benefits. The shared cost, the design, the implementation, the evaluation and any subsequent modifications should involve all relevant parties in the consortia. This joint ownership of a 'hands on' interventionist agenda to catchment change is at the core of Catchment Systems Engineering. In this paper we show a range of catchment engineering projects from the UK that have addressed multi-disciplinary approaches to flooding, pollution and ecosystem management, whilst maintaining economic food production. Examples using soft engineered features such as wetlands, ponds, woody debris dams and infiltration zones will be shown. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Evidence that impacts can be achieved at local catchment scale will be introduced. Catchment Systems Engineering is a concept that relies on all relevant parties

  16. CHUM: a hydrochemical model for upland catchments

    NASA Astrophysics Data System (ADS)

    Tipping, Edward

    1996-01-01

    CHUM (CHemistry of the Uplands Model) simulates soil-water chemical interactions and water flows in upland catchments with acid soils. The chemical interactions are described with the equilibrium speciation code WHAM, which emphasises the interactions of inorganic chemical species with solid-phase and dissolved organic matter, and also considers inorganic solution speciation and sorption reactions of fulvic acid. Of special significance is the treatment of aluminium chemistry; control of dissolved aluminium concentrations is assumed to be due primarily to complexation reactions with solid phase organic matter, whereas previous models have postulated equilibrium with mineral phases or simple ion-exchange. In addition, CHUM takes nitrogen transformations and weathering (dissolution) reactions into account. The catchment is conceptualised as a series of columns consisting of two soil horizons and an underlying permeable or fractured bedrock zone. Water flows are described with a hydrological submodel that distinguishes immobile water present in soil micropores (which is in chemical equilibrium with the soil solids) from mobile drainage water. The mobile water can move vertically from one horizon to another, from one column to the column immediately downslope, or as outflow from a column adjacent to a stream or lake. Solutes exchange between the mobile and immobile compartments. The model runs on a daily time-step. The fundamentals of the model are given, together with a description of its application to a site in the English Lake District.

  17. Pesticide modelling for a small catchment using SWAT-2000.

    PubMed

    Kannan, Narayanan; White, Sue M; Worrall, Fred; Whelan, Mick J

    2006-01-01

    Pesticides in stream flow from the 142 ha Colworth catchment in Bedfordshire, UK were monitored from October 1999 to December 2000. About 47% of the catchment is tile-drained and different pesticides and cropping patterns have recently been evaluated in terms of their effect on nutrient and pesticide losses to the stream. The data from Colworth were used to test soil and water assessment tool (SWAT) 2000 predictions of pesticide concentrations at the catchment outlet. A sound model set-up to carry out pesticide modelling was created by means of hydrological modelling with proper simulation of crop growth and evapotranspiration. The pesticides terbuthylazine, terbutryn, cyanazine and bentazone were modelled. There was close agreement between SWAT-predicted pesticide concentration values and observations. Scenario trials were conducted to explore management options for reducing pesticide loads arriving at the catchment outlet. The results obtained indicate that SWAT can be used as a tool to understand pesticide behavior at the catchment scale.

  18. Catchments' hedging strategy on evapotranspiration for climatic variability

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Ding, Wei; Li, Yu; Tang, Yin; Wang, Dingbao

    2016-11-01

    In this paper, we test the hypothesis that natural catchments utilize hedging strategy for evapotranspiration and water storage carryover with uncertain future precipitation. The hedging strategy for evapotranspiration in catchments under different levels of water availability is analytically derived with marginal utility principle. It is found that there exists hedging between evapotranspiration for present and future only with a portion of water availability. Observation data sets of 160 catchments in the United States covering the period from 1983 to 2003 demonstrate the existence of hedging in catchment hydrology and validate the proposed hedging strategy. We also find that more water is allocated to carryover storage for hedging against the future evapotranspiration deficit in the catchments with larger aridity indexes or with larger variability in future precipitation, i.e., long-term climate and precipitation variability control the degree of hedging.

  19. Root reinforcement and its implications in shallow landsliding susceptibility on a small alpine catchment

    NASA Astrophysics Data System (ADS)

    Morandi, M. C.; Farabegoli, E.; Onorevoli, G.

    2012-04-01

    Roots shear resistance offers a considerable contribution to hill-slope stability on vegetated terrains. Through the pseudo-cohesion of shrubs, trees and turf's roots, the geomechanical properties of soils can be drastically increased, exerting a positive influence on the hillslope stability. We analysed the shallow landsliding susceptibility of a small alpine catchment (Duron valley, Central Dolomites, Italy) that we consider representative of a wide altitude belt of the Dolomites (1800 - 2400 m a.s.l). The catchment is mostly mantled by grass (Nardetum strictae s.l.), with clustered shrubs (Rhododendron hirsutum and Juniperus nana), and trees (Pinus cembra, Larix decidua and Picea abies). The soil depth, investigated with direct and indirect methods, ranges from 0 to 180 cm, with its peak at the hollow axes. Locally, the bedrock, made of Triassic volcanic rocks, is deeply incised by the Holocene drainage network. Intensive grazing of cows and horses pervades the catchment area and cattle-trails occupy ca 20% of the grass cover. We used laboratory and field tests to characterize the geotechnical properties of these alpine soils; moreover we designed and tested an experimental device that measures, in situ, the shear strengths of the grass mantle. In the study area we mapped 18 shallow landslides, mostly related to road cuts and periodically reactivated as retrogressive landslides. The triggering mechanisms of these shallow landslides were qualitatively analysed at large scale and modelled at smaller scale. We used SHALSTAB to model the shallow landsliding susceptibility of the catchment at the basin scale and SLIDE (RocScience) to compute the Safety Factor at the versant scale. Qualitative management solutions are provided, in order to reduce the shallow landsliding susceptibility risk in this alpine context.

  20. Examining Sediment-bound Radiocesium Dynamics in Two Fukushima Coastal Catchments with Sediment Fingerprinting Techniques

    NASA Astrophysics Data System (ADS)

    Laceby, J. P.; Lepage, H.; Bonté, P.; Joron, J. L.; Onda, Y.; Lefèvre, I.; Ayrault, S.; Evrard, O.

    2015-12-01

    The Fukushima Dai-ichi nuclear power plant accident resulted in the significant fallout of radiocesium (137Cs and 134Cs) over the Fukushima region. After deposition on the soil surface, radiocesium is primarily bound to fine soil particles. Subsequently, rainfall and snow melt run-off events result in the downstream migration of radiocesium. Understanding the spatial distribution and relative contribution of different sediment sources is therefore fundamental to the management of radiocesium migration. Sediment fingerprinting techniques were used to determine the location and relative contributions of different sediment sources in the Mano and Niida Rivers, in the Fukushima region. First, we modelled the relative contributions of radiocesium from the upstream portions of the catchment, that received greater proportions of the fallout (e.g. >20 kBq kg-1), to sediment sampled in the downstream coastal regions. Second, we examined the elemental geochemistry of the major soil types (e.g. Andosols, Cambisols, Fluvisols) within these catchments and modelled their relative contribution to sediment sampled throughout these catchments. Elemental composition was measured with neutron activation analysis, radiocesium with gamma-spectrometry and a distribution modelling approach quantified source contributions. In the Mano River ~20% of the radiocesium sampled was modelled to be derived from the upstream area compared to ~50% in the Niida River. The highest contribution of upstream radiocesium was modelled after the typhoon seasons in 2011 and 2013. Fluvisols were found to be the dominant source of sediment (76%). The dominance of Fluvisols indicates that sediments are likely derived from sources that are highly connected to the river network (e.g. rice paddy fields). Understanding the relative contributions of these different sediment sources will allow for more direct management of sediment and thus radiocesium transfers in these Fukushima coastal catchments.

  1. Linking nitrogen cycling and export with variable source area dynamics in forested and urbanizing catchments

    NASA Astrophysics Data System (ADS)

    Band, L. E.; Tague, C. E.; Groffman, P.; Belt, K.

    2001-05-01

    One of the goals of the Baltimore Urban LTER site is to investigate how interactions between ecological processes and urban land use effect ecosystem functions, such as the cycling and export of nutrients. As part of this project, nitrogen export from Pond Branch, a 41 hectare forested catchment in Baltimore County, has been monitored since 1998 and is compared with nitrogen export from neighboring agricultural and urbanizing catchments. To better understand the spatial structure of nitrogen cycling and export processes in this region, a GIS and physically based, hydro-ecological model is used to investigate the interactions between soil water levels, flowpath dynamics and nitrogen cycling and export in Pond Branch. Rates of key ecosystem processes including vegetation uptake, litterfall, decomposition, mineralization, nitrification and denitrification vary in regular spatial and temporal patterns in response to meteorologically driven variations in soil water, temperature and biological activity as well as decadal level variations in canopy composition and extent. Alteration in the distribution of nitrogen sinks and sources in the landscape are particularly manifest in the dynamics of riparian areas that result in peak nitrogen export during the active growing season in this catchment. Urbanization effects can be added to the simulation by altering irrigation and fertilization rates, vegetation patterns and by altering hydrologic flowpaths through the construction of roads and sewer networks. The model is used to investigate current nitrogen cycling and export patterns and scenarios for urbanization of the Pond Branch catchment. Variation in the pattern of land cover change and infrastructure development with respect to the existing pattern of vegetation and topographic controls on nitrogen cycling is shown by the model to influence the impact of urbanization on nitrogen export.

  2. 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

  3. Climate, runoff and landuse trends in the Owo River Catchment in Nigeria

    NASA Astrophysics Data System (ADS)

    Adegun, O.; Odunuga, S.; Ajayi, O. S.

    2015-06-01

    The Owo River is an important surface water source in Lagos particularly to the western section. It is the source of direct water intake for water supply by Lagos State Water Corporation to Amuwo-Odofin, Ojo and parts of Badagry Local Government Areas. This paper examines the complex interactions and feedbacks between many variables and processes within that catchment and analyses the future ability of this semi-urban watershed in sustaining water supply in the face of cumulative environmental change. Stationarity analysis on rainfall, change detection analysis and morphometry analysis were combined to analyse the non-stationarity of Owo River catchment. On rainfall trend analysis, since the correlation coefficient (0.38) with test statistic of 2.17 did not satisfy the test condition we concluded that there is trend and that rainfall in the watershed is not stationary. The dominant land use impacting on the bio-geochemical fluxes is built up area (including structures and paved surfaces) which grew from about 142.92 km2 (12.20%) in 1984 to 367.22 km2 (31.36%) in 2013 recording gain of 224.3 km2 at average growth rate of 7.73 km2 per annum. Total length of streams within the catchment reduced from 622.24 km in 1964 to 556 km in 2010, while stream density reduced from 0.53 in 1964 to 0.47 in 2010 an indication of shrinking hydrological network. The observed trends in both natural and anthropogenic processes indicated non-stationarity of the hydrological fluxes within the Catchment and if this continues, the urban ecosystem services of water supply will be compromised.

  4. Runoff Variability in Field-scale Catchments and the Implications for Rainffall-Runoff Modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Shuster, W.

    2004-12-01

    In this study long-term rainfall runoff records for two agricultural catchments (ca. 0.5 ha) in the USDA - Agricultural Research Service North Appalachian Experimental Watershed (Coshocton, OH) network were used to address the inter-event and inter-catchment variability of field-scale runoff processes. Through analyses of flood frequency and flow duration, the adjacent fallowed watersheds (WS106 and WS121) were found to be similar in terms of annual flood peaks, but less so in terms of the distribution of their discharge rates. Further investigation was focused on event-scale variations of runoff response and whether these variations can be effectively captured by rainfall-runoff models, which included: a) TR-20 (a lumped model); b) EPA-SWMM (a semi-distributed model); and c) GSSHA (a grid-based, fully distributed model). Each model was used to simulate 41 selected runoff episodes recorded in each of the two catchments, and subsequently calibrated to yield parameter values that maximize the correlation between the simulated and observed runoff peaks. Our results indicate that, despite calibration, the hydrographs derived from all models deviated considerably from actual observations, and on the basis of inter-event fluctuations, which furthermore lacked a conspicuous dependence on the magnitude of runoff peaks. Our findings suggest that, in the absence of information on rainfall distribution and soil moisture, distributed models may not be superior to lumped ones in forecasting runoff responses of field scale catchments; and the correspondence between runoff mechanisms and model representations needs to be better understood and accounted for in order to limit the uncertainties of model predictions.

  5. ANN modeling for flood prediction in the upstream Eure's catchment (France)

    NASA Astrophysics Data System (ADS)

    Kharroubi, Ouissem; masson, Eric; Blanpain, Olivier; Lallahem, Sami

    2013-04-01

    Rainfall-Runoff relationship at basin scale is strongly depending on the catchment complexity including multi-scale interactions. In extreme events cases (i.e. floods and droughts) this relationship is even more complex and differs from average hydrological conditions making extreme runoff prediction very difficult to achieve. However, flood warning, flood prevention and flood mitigation rely on the possibility to predict both flood peak runoff and lag time. This point is crucial for decision making and flood warning to prevent populations and economical stakes to be damaged by extreme hydrological events. Since 2003 in France, a dedicated state service is in charge of producing flood warning from national level (i.e. SCHAPI) to regional level (i.e. SPC). This flood warning service is combining national weather forecast agency (i.e. Meteo France) together with a fully automated realtime hydrological network (i.e. Rainfall-Runoff) in order to produce a flood warning national map online and provide a set of hydro-meteorological data to the SPC in charge of flood prediction from regional to local scale. The SPC is in fact the flood service delivering hydrological prediction at operational level for decision making about flood alert for municipalities and first help services. Our research in collaboration with the SPC SACN (i.e. "Seine Aval et fleuves Côtiers Normands") is focused on the implementation of an Artificial Neural Network model (ANN) for flood prediction in deferent key points of the Eure's catchment and main subcatchment. Our contribution will focus on the ANN model developed for Saint-Luperce gauging station in the upstream part of the Eure's catchment. Prediction of extreme runoff at Saint-Luperce station is of high importance for flood warning in the Eure's catchment because it gives a good indicator on the extreme status and the downstream propagation of a potential flood event. Despite a good runoff monitoring since 27 years Saint Luperce flood

  6. Cross-scale interactions between surface components and rainfall properties. Non-linearities in the hydrological and erosive behavior of semiarid catchments

    NASA Astrophysics Data System (ADS)

    Rodríguez-Caballero, Emilio; Cantón, Yolanda; Lazaro, Roberto; Solé-Benet, Albert

    2014-09-01

    Non-vegetated areas in arid and semiarid ecosystems are usually covered by biological soil crusts (BSCs), which modify many surface properties and reduce soil erosion at local spatial scales. Nevertheless, runoff generated in these areas could increase downstream erosion, or on the contrary, supply water to downslope plants, which act as surface obstructions slowing down runoff, trapping sediments and thus reducing water erosion. However, their buffer capacity might be overwhelmed during some torrential rains, increasing catchment connectivity and modifying the hydrological behavior and subsequent water erosion measured at the catchment outlet. To progress in the knowledge of the effect of the interactions between BSCs and vegetation on runoff generation and water erosion at catchment scale, the long term hydrological response of semiarid badlands with an important cover of BSCs has been studied. This effect has been analyzed using piecewise regression analysis to find any possible break point in the runoff response of the catchment to rainfall, attributable to variations in the hydrological connectivity of the catchment. Once we found this break point, we used it to divide the database in two sub-databases, and we built two structural equation models (SEM) to identify the main hydrological drivers controlling runoff generation and water erosion at sub-datasets, corresponding with different stages of catchment connection. Our results show that during low magnitude rainfall events, runoff and erosion measured at the catchment outlet come essentially from physically crusted areas directly connected to the channel network and are controlled by rainfall intensity, whereas runoff generated in areas with BSCs is reinfiltrated downstream into local vegetation patches. However, during high-magnitude events, vegetated buffers are saturated, connecting areas covered by BSCs with the channel network and increasing the catchment efficiency in exporting water out of the system

  7. Characterising groundwater-dominated lowland catchments: the UK Lowland Catchment Research Programme (LOCAR)

    NASA Astrophysics Data System (ADS)

    Wheater, H. S.; Peach, D.; Binley, A.

    2007-01-01

    This paper reports on a major UK initiative to address deficiencies in understanding the hydro-ecological response of groundwater-dominated lowland catchments. The scope and objectives of this national programme are introduced and focus on one of three sets of research basins - the Pang/Lambourn Chalk catchments, tributaries of the river Thames in southern England. The motivation for the research is the need to support integrated management of river systems that have high ecological value and are subject to pressures that include groundwater abstraction for water supply, diffuse pollution, and land use and climate change. An overview of the research programme is provided together with highlights of some current research findings concerning the hydrological functioning of these catchments. Despite the importance of the Chalk as a major UK aquifer, knowledge of the subsurface movement of water and solutes is poor. Solute transport in the dual porosity unsaturated zone depends on fracture/matrix interactions that are difficult to observe; current experimental and modelling research supports the predominance of matrix flow and suggests that slow migration of a time-history of decades of nutrient loading is occurring. Groundwater flows are complex; catchments vary seasonally and are ill-defined and karst features are locally important. Groundwater flow pathways are being investigated using natural and artificial geochemical tracers based on experimental borehole arrays; stream-aquifer interaction research is using a combination of geophysics, borehole array geochemistry and longitudinal profiles of stream flow and solutes. A complex picture of localised subsurface inflows, linked to geological controls and karst features, and significant longitudinal groundwater flow below the river channel is emerging. Management implications are discussed. Strategies to control surface application of nutrients are expected to have little effect on groundwater quality for several

  8. Catchment tomography - An approach for spatial parameter estimation in catchment hydrology

    NASA Astrophysics Data System (ADS)

    Walther, Dorina; Kurtz, Wolfgang; Hendricks-Franssen, Harrie-Jan; Kollet, Stefan

    2016-04-01

    Though forecast accuracy of hydrological models has improved in the last decades due to the development of more powerful and distributed models, uncertainties in forcings and model parameters are still challenging issues limiting the forecast reliability. As the number of unknown model parameters is generally large for distributed models, batch calibration methods usually lead to different parameter sets resulting in the same model accuracy. Catchment tomography presents an approach to reduce this non-uniqueness problem in hydrological parameter estimation by applying a moving transmitter-receiver concept on a catchment. Radar based precipitation fields serve as the transmitters and stream water gauge observations, the receivers, are sequentially assimilated into the model. The integrated stream gauge signals are resolved by a joint state-parameter update with the Ensemble Kalman Filter. The uncertain parameters are continuously constrained by sequentially integrating new information. Forward simulations are performed with the variably saturated subsurface and overland flow model ParFlow, which has been coupled to the Parallel Data Assimilation Framework (PDAF). In a first step in developing the method, catchment tomography was applied in a synthetic study of a simplified two dimensional catchment with pure overland flow (no subsurface flow) to estimate the spatially distributed Manning's roughness coefficient. The roughness coefficient was distributed in two and four zones and was updated applying different real radar precipitation time series and different initial parameter distributions. The parameters were successfully estimated with only 64 realizations over a simulation period of 30 days with hourly state and parameter updates. The error in the ensemble mean estimated parameters was reduced from up to 500% to less than 4% for all zones of both scenarios, independent from the initial ensemble mean value, if an appropriate initial ensemble spread was applied

  9. Suspended sediment fluxes in the Humber catchment, UK

    NASA Astrophysics Data System (ADS)

    Wass, Paul D.; Leeks, Graham J. L.

    1999-05-01

    An extensive sediment monitoring network was established within the LOIS programme, involving 10 of the main tributaries of the River Humber (UK). Its primary purpose was to measure the flux of suspended sediment to the estuary. A turbidity monitoring system was developed to provide a continuous record of suspended sediment concentration in the rivers, from which the fluxes were calculated. Linear relationships were established between suspended sediment concentration and turbidity (with slopes varying from 0·89 to 1·69) to enable the conversion of nephelometric turbidity [NTU] to suspended sediment concentration [mg l-1]. Potential uncertainties were identified and quantified. The suspended sediment flux to the Humber (November 1994-October 1997) was calculated to be 699 861 t, equivalent to a yield of 15 t km-2 yr-1. Large temporal and spatial variations in the flux were measured during the monitoring period, in response to factors such as climate, land use, catchment scale, deposition and reservoir trapment. The particle size composition of the suspended sediment was measured and found to vary little, except at very high discharges, when it coarsened. The organic content of the sediment was found to be directly related to the discharge of sewage effluent to the rivers.

  10. Towards catchment classification in data-scarce regions

    SciTech Connect

    Auerbach, Daniel A.; Buchanan, Brian P.; Alexiades, Alex V.; Anderson, Elizabeth P.; Encalada, Andrea C.; Larson, Erin I.; McManamay, Ryan A.; Poe, Gregory L.; Walter, M. Todd; Flecker, Alexander S.

    2016-01-29

    Assessing spatial variation in hydrologic processes can help to inform freshwater management and advance ecological understanding, yet many areas lack sufficient flow records on which to base classifications. Seeking to address this challenge, we apply concepts developed in data-rich settings to public, global data in order to demonstrate a broadly replicable approach to characterizing hydrologic variation. The proposed approach groups the basins associated with reaches in a river network according to key environmental drivers of hydrologic conditions. This initial study examines Colorado (USA), where long-term streamflow records permit comparison to previously distinguished flow regime types, and the Republic of Ecuador, where data limitations preclude such analysis. The flow regime types assigned to gages in Colorado corresponded reasonably well to the classes distinguished from environmental features. The divisions in Ecuador reflected major known biophysical gradients while also providing a higher resolution supplement to an existing depiction of freshwater ecoregions. Although freshwater policy and management decisions occur amidst uncertainty and imperfect knowledge, this classification framework offers a rigorous and transferrable means to distinguish catchments in data-scarce regions. The maps and attributes of the resulting ecohydrologic classes offer a departure point for additional study and data collection programs such as the placement of stations in under-monitored classes, and the divisions may serve as a preliminary template with which to structure conservation efforts such as environmental flow assessments.

  11. Towards catchment classification in data-scarce regions

    DOE PAGES

    Auerbach, Daniel A.; Buchanan, Brian P.; Alexiades, Alex V.; ...

    2016-01-29

    Assessing spatial variation in hydrologic processes can help to inform freshwater management and advance ecological understanding, yet many areas lack sufficient flow records on which to base classifications. Seeking to address this challenge, we apply concepts developed in data-rich settings to public, global data in order to demonstrate a broadly replicable approach to characterizing hydrologic variation. The proposed approach groups the basins associated with reaches in a river network according to key environmental drivers of hydrologic conditions. This initial study examines Colorado (USA), where long-term streamflow records permit comparison to previously distinguished flow regime types, and the Republic of Ecuador,more » where data limitations preclude such analysis. The flow regime types assigned to gages in Colorado corresponded reasonably well to the classes distinguished from environmental features. The divisions in Ecuador reflected major known biophysical gradients while also providing a higher resolution supplement to an existing depiction of freshwater ecoregions. Although freshwater policy and management decisions occur amidst uncertainty and imperfect knowledge, this classification framework offers a rigorous and transferrable means to distinguish catchments in data-scarce regions. The maps and attributes of the resulting ecohydrologic classes offer a departure point for additional study and data collection programs such as the placement of stations in under-monitored classes, and the divisions may serve as a preliminary template with which to structure conservation efforts such as environmental flow assessments.« less

  12. Pollution from urban development and setback outfalls as a catchment management measure for river water quality improvement

    NASA Astrophysics Data System (ADS)

    Allen, Deonie; Haynes, Heather; Arthur, Scott

    2016-04-01

    Urban development causes an increase in fine sediment and heavy metal stormwater pollution. Pollution load estimation theorises that stormwater pollutant load and type are strongly, directly influenced by contributing catchment land use. The research presented investigates the validity of these assumptions using an extensive novel field data set of 53 catchments. This research has investigated the relationships between land use and pollutant concentrations (Cu, Zn, Pb, Ni, Ca, Ba, Sn, Mn) in urban stormwater outfall sediments. Cartographic and aerial photography data have been utilised to delineate the surface and subsurface contributing catchment land use. A zoned sub-catchment approach to catchment characterisation of stormwater pollutant concentration has been defined and tested. This method effectively describes the specific land use influence on pollutant concentrations at the stormwater outfall, showing strong dependency with road length, brake points, impervious area and open space. Road networks and open space are found to influence land use, and thus stormwater pollution, closer to stormwater outfall/receiving waterbody suggesting storage, treatment, assimilation, loss or dilution of the land use influence further away from stormwater outfall. An empirical description has been proposed with which to predict outfall pollutant contributions to the receiving urban waterbody based on catchment land use information. With the definition and quantification of contributing catchment specific fine sediment and urban heavy metal pollutants, the influence of urban stormwater outfall management on the receiving watercourse has been considered. The locations of stormwater outfalls, and their proximity to the receiving waterway, are known as key water quality and river health influences. Water quality benefits from the implementation of stormwater outfalls set back from the receiving waterway banks have been investigated using the catchment case study. Setback outfalls

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

    PubMed Central

    Wagener, Thorsten; McGlynn, Brian

    2015-01-01

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

  14. A distributed continuous simulation model to identify critical source areas of phosphorus at the catchment scale: model description

    NASA Astrophysics Data System (ADS)

    Koo, B. K.; Dunn, S. M.; Ferrier, R. C.

    2005-08-01

    This paper presents CAMEL (Chemicals from Agricultural Management and Erosion Losses), a distributed continuous simulation model to simulate daily phosphorus (P) transformations and transport at the catchment scale. CAMEL is a process-oriented mass-balance model that is based on both analytical and numerical approaches. In the model, a catchment is represented using a network of square grid cells each of which is comprised of various storages of water, sediment and P. Most of hydrological processes, soil erosion, sediment transport, and P transformations and transport are described using process-based equations. The P transformations between five P storages (active organic, stable organic, labile, active inorganic, and stable organic) are described using first-order kinetic equations. A comprehensive cascade routing scheme is used to simulate P retention and transport along the channel system. Dissolved P is also transported by groundwater flows, described using a two-dimensional Boussinesq equation. CAMEL simulates both surface and subsurface processes explicitly and therefore is suitable for catchment-scale applications. The distributed, process-oriented structure of CAMEL enables the model to be used for identifying critical source areas of P at the catchment-scale. CAMEL is also computationally efficient, allowing for long-term scale applications.

  15. Comparison of drought occurrence in selected Slovak and Czech catchments

    NASA Astrophysics Data System (ADS)

    Fendekova, Miriam; Fendek, Marian; Porubska, Diana; Hanel, Martin; Horacek, Stanislav; Martinkova, Marta; Vizina, Adam

    2014-05-01

    The presented study is focused on the analysis and comparison of hydrological drought occurrence, development and duration in six small to middle sized catchments in the Czech Republic (CZ) and Slovakia. The main questions to be answered are: (1) are there correlations between the physical conditions in the catchments and drought occurrence, and (2) does the spatial trend of drought occurrence exist. The Žitava catchment is located in the central western part of Slovakia having runoff dominated by rainfall with the contribution of snow melting during the spring period. The Belá River catchment is located on the contact of Západné and Vysoké Tatry Mts. in the north of Slovakia. The runoff is snow to snow-rain combined type. The Ľupčianka catchment is located on the northern slopes of the Nízke Tatry Mts. in the northern part of the central Slovakia. The runoff regime is snow-rain combined in the upper part of the catchment, and of rain-snow type in the rest of catchment. The Rakovnický potok brook (CZ) has its spring in Rakovnická pahorkatina hilly land. Runoff is dominated by rainfall, quite heavily influenced by water uptakes in the catchment. The Teplá River (CZ) originates in peat meadows in the western part of the Czech Republic. Runoff is dominated by rainfall. The Metuje catchment (CZ) is formed by Adršsbach-Teplické stěny Upland. The headwater part is typical by deeply incest valleys, table mountains and pseudokarst caves. The discharge is fed dominantly by groundwater. The streamflow drought was characterized using discharge data, the groundwater drought using the base flow values. The local minimum method was used for base flow separation. The threshold level method (Q80, BF80) and the sequent peak algorithm were used for calculation of drought duration in discharge and base flow time series. The data of the same three decades of the common period (1971 - 1980, 1981 - 1990 and 1991 - 2000) were used. The resulting base flow values along with

  16. Flow path and travel time dynamics in a lowland catchment.

    NASA Astrophysics Data System (ADS)

    van der Velde, Ype; de Rooij, Gerrit

    2016-04-01

    The distribution of time it takes water from the moment of precipitation to reach the catchment outlet is widely used as a characteristic for catchment flow path contributions, catchment vulnerability to pollution spreading and pollutant loads from catchments to downstream waters. However, this distribution tends to vary in time driven by variability in precipitation and evapotranspiration. Catchment scale mixing of water controls how dynamics in rainfall and evapotranspiration are translated into dynamics of travel time distributions. In this presentation we use the concept of StorAge selection (SAS) functions, that quantify catchment scale mixing of water, to describe chloride and nitrate flow. We will show how SAS functions relate to the topography and subsurface and how they are effective in describing nitrate and chloride transport. The presented analyses will combine unique datasets of high-frequency discharge and water quality concentrations with conceptual models of water flow and solute transport. Remarkable findings are the large contrasts in travel times between lowland and sloping catchments and the strong relationship between evapotranspiration and stream water nutrient concentration dynamics.

  17. Pesticide uses and transfers in urbanised catchments.

    PubMed

    Blanchoud, Hélène; Farrugia, Frédéric; Mouchel, Jean Marie

    2004-05-01

    An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 microg l(-1) due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 microg l(-1)), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water.

  18. Catchments of general practice in different countries– a literature review

    PubMed Central

    2014-01-01

    The purpose of this paper is to review the current research on catchment areas of private general practices in different developed countries because healthcare reform, including primary health care, has featured prominently as an important political issue in a number of developed countries. The debates around health reform have had a significant health geographic focus. Conceptually, GP catchments describe the distribution, composition and profile of patients who access a general practitioner or a general practice (i.e. a site or facility comprising one or more general practitioners). Therefore, GP catchments provide important information into the geographic variation of access rates, utilisation of services and health outcomes by all of the population or different population groups in a defined area or aggregated area. This review highlights a wide range of diversity in the literature as to how GP catchments can be described, the indicators and measures used to frame the scale of catchments. Patient access to general practice health care services should be considered from a range of locational concepts, and not necessarily constrained by their place of residence. An analysis of catchment patterns of general practitioners should be considered as dynamic and multi-perspective. Geographic information systems provide opportunities to contribute valuable methodologies to study these relationships. However, researchers acknowledge that a conceptual framework for the analysis of GP catchments requires access to real world data. Recent studies have shown promising developments in the use of real world data, especially from studies in the UK. Understanding the catchment profiles of individual GP surgeries is important if governments are serious about patient choice being a key part of proposed primary health reforms. Future health planning should incorporate models of GP catchments as planning tools, at the micro level as well as the macro level, to assist policies on the

  19. Biogeochemical and Hydrological Heterogeneity and Emergent Archetypical Catchment Response Patterns

    NASA Astrophysics Data System (ADS)

    Jawitz, J. W.; Gall, H. E.; Rao, P. S.

    2014-12-01

    What can stream hydrologic and biogeochemical signals tell us about interactions among spatially heterogeneous hydrological and biogeochemical processes at the catchment-scale? We seek to understand how the spatial structure of solute sources coupled with both stationary and nonstationary hydroclimatic drivers affect observed archetypes of concentration-discharge (C-Q) patterns. These response patterns are the spatially integrated expressions of the spatiotemporal structure of solutes exported from managed catchments, and can provide insight into likely ecological consequences of receiving water bodies (e.g., wetlands, rivers, lakes, and coastal waters). We investigated the following broad questions: (1) How does the spatial correlation between the structure of flow-generating areas and biogeochemical source areas across a catchment evolve under stochastic hydro-climatic forcing? (2) What are the feasible hydrologic and biogeochemical responses that lead to the emergence of archetypical C-Q patterns? and; (3) What implications do these coupled dynamics have for catchment monitoring and implementation of management practices? We categorize the observed temporal signals into three archetypical C-Q patterns: dilution; accretion, and constant concentration. We applied a parsimonious stochastic model of heterogeneous catchments, which act as hydrologic and biogeochemical filters, to examine the relationship between spatial heterogeneity and temporal history of solute export signals. The core concept of the modeling framework is considering the type and degree of spatial correlation between solute source zones and flow generating zones, and activation of different portions of the catchments during rainfall events. Our overarching hypothesis is that each archetype C-Q pattern can be generated by explicitly linking landscape-scale hydrologic responses and spatial distributions of solute source properties within a catchment. We compared observed multidecadal data to

  20. Assessing the role of urban developments on storm runoff response through multi-scale catchment experiments

    NASA Astrophysics Data System (ADS)

    Wilkinson, Mark; Owen, Gareth; Geris, Josie; Soulsby, Chris; Quinn, Paul

    2015-04-01

    patterns in the timing and magnitude of the contributions of the different land use zones and their nested integrated runoff response at increasing scales. These can be clearly linked to variations in antecedent conditions and precipitation patterns. For low antecedent flow conditions, the main flood peak is dominated by urban origins (faster responding and larger in relative magnitude); for high antecedent flow conditions, rural (and peri-urban) sources are most dominant. A third type of response involves mixed events, where both rural and urban contributions interact and reinforce the peak flow response. Our analyses showed that the effectiveness of the GIs varied substantially between the different events, suggesting that their design could be improved by introducing variable drainage rates and strategic placements to allow for interactions with the stream network. However, more information is needed on the spatio-temporal variability in water sources, flow pathways and residence times. This is of particular importance to also assess other multiple benefits of GIs, including the impacts on water quality. These challenges are currently addressed in two new case study catchment in the North East of Scotland (10km2) which are undergoing major land use change from rural to urban. Here, integrated tracer and hydrometric data are being collected to characterise the integrated impacts of urbanisation and GIs on flow pathways (nature and length) and associated water quality.

  1. Assessing representative soil moisture at watershed scale of Maqu catchment using spatio-temporal statistical analysis

    NASA Astrophysics Data System (ADS)

    Bhatti, H. A.; Rientjes, T. H. M.; Verhoef, W.

    2012-04-01

    In this study the temporal stability concept by Vachaud et al. (1985) is selected to evaluate a soil moisture measuring network in the Maqu catchment (3200 km2) in the north eastern part of the Tibetan plateau. The network serves for validation of coarse scale (25-50 km) satellite soil moisture products and comprises 20 stations with probes installed at depths of 5, 10, 20, 40, 80 cm. Besides identifying the Representative Mean Soil Moisture (RMSM) station for each respective probe depth, we applied the concept to a time series of satellite based moisture products from the Advance Microwave Scanning Radiometer (AMSR-E) to evaluate if a RMSM pixel can be identified from the pixels that overlay the catchment. Analysis in this study serve to evaluate how well the satellite based moisture estimates match to observation at the RMSM stations for respective depths. We aim to evaluate if the RMSM can be estimated by the satellite product so to broaden the procedure to validate satellite images. We used moisture data for the year 2009 for which data is available at 15 minutes interval using ECH2O EC-TM probes. For each probe depth a Mean Relative Difference (MRD) plot is created to identify stations that are characterized by mean, wet and dry moisture conditions. The spearman non-parametric test and pearson's correlation coefficient test are used to analyze the temporal persistence of the ranks of the measuring stations. The analysis is applied to each probe depth to evaluate the effect of the measuring depth on determining the catchment RMSM. Similar analysis is carried out on the satellite soil moisture observations that cover a full hydrological year to identify a RMSM pixel. The result of the analysis on the network showed that the station that indicates RMSM changes for each probe depth and thus a single station that indicates the catchment RMSM cannot be identified. Results on identifying a RMSM pixel shows that such pixel can be identified, however in our case, a

  2. Components of the total water balance of an urban catchment.

    PubMed

    Mitchell, V Grace; McMahon, Thomas A; Mein, Russell G

    2003-12-01

    A daily model was used to quantify the components of the total urban water balance of the Curtin catchment, Canberra, Australia. For this catchment, the mean annual rainfall was found to be three times greater than imported potable water, and the sum of the output from the separate stormwater and wastewater systems exceeded the input of imported potable water by some 50%. Seasonal and annual variations in climate exert a very strong influence over the relative magnitude of the water balance components; this needs to be accounted for when assessing the potential for utilizing stormwater and wastewater within an urban catchment.

  3. Impact of spatial climate variability on catchment streamflow predictions

    NASA Astrophysics Data System (ADS)

    Patil, Sopan; Wigington, Jim; Leibowitz, Scott; Sproles, Eric; Comeleo, Randy

    2014-05-01

    The ability of hydrological models to predict a catchment's streamflow response serves several important needs of our society, such as flood protection, irrigation demand, domestic water supply, and preservation of fish habitat. However, spatial variability of climate within a catchment can negatively affect streamflow predictions if it is not explicitly accounted for in hydrological models. In this study, we examined the changes in streamflow predictability when a hydrological model is run with spatially variable (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model were implemented at 41 meso-scale (500 - 5000 km2) catchments in the Pacific Northwest region of USA (Oregon, Washington, and Idaho). We used two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyse the performance improvement with distributed model. Results showed that the distributed model performed better than the lumped model in 38 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone was insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM was a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV was a better predictor of performance improvement than IM. Based on the results, we conclude that: (1) catchments that have low homogeneity of moisture distribution are the obvious candidates for using spatially distributed meteorological inputs, and (2) catchments with homogeneous moisture distribution benefit from spatially distributed meteorological inputs if those catchments have high spatial variability of precipitation phase (rain vs. snow). Our use of spatially

  4. Observational techniques for constraining hydraulic and hydrologic models for use in catchment scale flood impact assessment

    NASA Astrophysics Data System (ADS)

    Owen, Gareth; Wilkinson, Mark; Nicholson, Alex; Quinn, Paul; O'Donnell, Greg

    2015-04-01

    There is an increase in the use of Natural Flood Management (NFM) schemes to tackle excessive runoff in rural catchments, but direct evidence of their functioning during extreme events is often lacking. With the availability of low cost sensors, a dense nested monitoring network can be established to provide near continuous optical and physical observations of hydrological processes. This paper will discuss findings for a number of catchments in the North of England where land use management and NFM have been implemented for flood risk reduction; and show how these observations have been used to inform both a hydraulic and a rainfall-runoff model. The value of observations in understanding how measures function is of fundamental importance and is becoming increasingly viable and affordable. Open source electronic platforms such as Arduino and Raspberry Pi are being used with cheap sensors to perform these tasks. For example, a level gauge has been developed for approximately €110 and cameras capable of capturing still or moving pictures are available for approximately €120; these are being used to better understand the behaviour of NFM features such as ponds and woody debris. There is potential for networks of these instruments to be configured and data collected through Wi-Fi or other wireless networks. The potential to expand informative networks of data that can constrain models is now possible. The functioning of small scale runoff attenuation features, such as offline ponds, has been demonstrated at the local scale. Specifically, through the measurement of both instream and in-pond water levels, it has been possible to calculate the impact of storing/attenuating flood flows on the adjacent river flow. This information has been encapsulated in a hydraulic model that allows the extrapolation of impacts to the larger catchment scale, contributing to understanding of the scalability of such features. Using a dense network of level gauges located along the main

  5. Water and chemical recharge in subsurface catchment: observations and consequences for modeling

    NASA Astrophysics Data System (ADS)

    Gascuel-odoux, C.; Aquilina, L.; Faucheux, M.; Merot, P.; Molenat, J.; de Monteti, V.; Sebilo, M.; Rouxel, M.; Ruiz, L.

    2011-12-01

    Shallow groundwater that develops on hillslopes is the main compartment in headwater catchments for flow and solute transport to rivers. Although spatial and temporal variations in its chemical composition are reported in the literature, there is no coherent description of the way these variations are organized, nor is there an accepted conceptual model for the recharge mechanisms and flows in the groundwater involved. We instrumented an intensive farming and subsurface dominant catchment located in Oceanic Western Europe (France), included in AgrHyS catchments (for Agro-Hydro-SyStem) and a part of the French network of catchments for environmental research (SOERE RBV dedicated to the Critical Zone). It is strongly constrained by anthropogenic pressures (agriculture) and is characterized by a clear non-equilibrium status. A network of 42 nested piezometers was installed along a 200 m hillslope allowing water sampling in the permanent water table as well as in what we call the fluctuating zone, characterized by seasonal alternance of saturated and unsaturated conditions. Water composition was monitored at high frequency (weekly) over a 3-year period for major anion composition and over a one year period for detailed 15N, CFC, SF6 and other dissolved gases composition. The results demonstrated that (i) the anionic composition in water table fluctuation zone varied significantly compared to deeper portions of the aquifer on the hillslope, confirming that this layer constitutes a main compartment for the mixing of new recharge water and old groundwater, (ii) seasonally, the variations of 15N and CFC are much higher during the recharge period than during the recession period, confirming the preferential flow during early recharge events, iii) variations of nitrate 15N and O18 composition was suggesting any significant denitrification process in the fluctuating zone, confirming the dominance of the mixing processes in the fluctuating zone, iv) deeper parts of the aquifer

  6. Susceptibility analysis for landslides in the Xiangxi catchment (Three Gorges Reservoir area / China)

    NASA Astrophysics Data System (ADS)

    Rohn, J.; Ehret, D.; Xiang, W.

    2009-04-01

    The Xiangxi River is a tributary of the Yangtze River. In 2009 the Three Gorges Reservoir will reach its final retention water elevation level (175 m asl). Parts of the Xiangxi valley will then flooded. Especially Jurassic sedimentary layers are predestined for intense landslides in this area. As a first step a landslide inventory map is produced. All slopes influenced directly by impoundment are mapped geotechnically in detail to assess the spatial distribution of the landslides and their shape. Furthermore, two sub-catchments in the wide-stretched catchment area of the Xiangxi River were chosen for intense investigation. All in all, about 200 km2will finally be mapped geotechnically in detail to provide data for continuative investigations. The investigation fields are divided into test and training areas for further analysis using the neural networks method. By this means the susceptibility for landslides in dependency of different features, like lithology, slope angle, exposition, distance to the river, etc will be analysed. In a second step the results of the neural network analysis will be the base of a more regional landslide susceptibility analysis for the whole catchment area of the Xiangxi River. The performance of the method will be tested by additional inspections in areas that have been found to have a high susceptibility for landslides. These works are part of the joint research project "Yangtze: land use change - erosion - landslides" financed by the German Federal Ministry of Education and Research (BMBF). Joint aim of this project is to produce a landslide and erosion risk map for the whole region and to analyse the land use change caused by the impoundment of the Three Gorges Dam in this area.

  7. Approaches for quantifying and managing diffuse phosphorus exports at the farm/small catchment scale.

    PubMed

    McDowell, Richard W; Nash, David; George, Anja; Wang, Q J; Duncan, Ruth

    2009-01-01

    Quantifying and managing diffuse P losses from small catchments or at the farm scale requires detailed knowledge of farming practices and their interaction with catchment processes. However, detailed knowledge may not be available and hence modeling is required. This paper demonstrates two approaches to developing tools that assist P losses from New Zealand or Australian dairy farms. The first is largely empirical and separates sources of P within a paddock into soil, fertilizer, dung, and treading impacts (including damage to grazed pasture). This information is combined with expert knowledge of hydrological processes and potential point sources (e.g., stream crossings) to create a deterministic model that can be used to evaluate the most cost and labor efficient method of mitigating P losses. For instance, in one example, 45% of annual P lost was attributed to the application of superphosphate just before a runoff event for which a mitigation strategy could be to use a less water soluble P fertilizer. The second approach uses a combination of interviews, expert knowledge and relationships to develop a Bayesian Network that describes P exports. The knowledge integration process helped stakeholders develop a comprehensive understanding of the problem. The Network, presented in the form of a "cause and effect", diagram provided a simple, visual representation of current knowledge that could be easily applied to individual circumstances and isolate factors having the greatest influence on P loss. Both approaches demonstrate that modeling P losses and mitigation strategies does not have to cover every process or permutation and that a degree of uncertainty can be handled to create a working model of P losses at a farm or small catchment scale.

  8. CNMM: a Catchment Environmental Model for Managing Water Quality and Greenhouse Gas Emissions

    NASA Astrophysics Data System (ADS)

    Li, Y.

    2015-12-01

    Mitigating agricultural diffuse pollution and greenhouse gas emissions is a complicated task due to tempo-spatial lags between the field practices and the watershed responses. Spatially-distributed modeling is essential to the implementation of cost-effective and best management practices (BMPs) to optimize land uses and nutrient applications as well as to project the impact of climate change on the watershed service functions. CNMM (the Catchment Nutrients Management Model) is a 3D spatially-distributed, grid-based and process-oriented biophysical model comprehensively developed to simulate energy balance, hydrology, plant/crop growth, biogeochemistry of life elements (e.g., C, N and P), waste treatment, waterway vegetation/purification, stream water quality and land management in agricultural watersheds as affected by land utilization strategies such as BMPs and by climate change. The CNMM is driven by a number of spatially-distributed data such as weather, topography (including DEM and shading), stream network, stream water, soil, vegetation and land management (including waste treatments), and runs at an hourly time step. It represents a catchment as a matrix of square uniformly-sized cells, where each cell is defined as a homogeneous hydrological response unit with all the hydrologically-significant parameters the same but varied at soil depths in fine intervals. Therefore, spatial variability is represented by allowing parameters to vary horizontally and vertically in space. A four-direction flux routing algorithm is applied to route water and nutrients across soils of cells governed by the gradients of either water head or elevation. A linear channel reservoir scheme is deployed to route water and nutrients in stream networks. The model is capable of computing CO2, CH4, NH3, NO, N2O and N2 emissions from soils and stream waters. The CNMM can serve as an idea modelling tool to investigate the overwhelming critical zone research at various catchment scales.

  9. Shuttle radar DEM hydrological correction for erosion modelling in small catchments

    NASA Astrophysics Data System (ADS)

    Jarihani, Ben; Sidle, Roy; Bartley, Rebecca

    2016-04-01

    Digital Elevation Models (DEMs) that accurately replicate both landscape form and processes are critical to support modelling of environmental processes. Catchment and hillslope scale runoff and sediment processes (i.e., patterns of overland flow, infiltration, subsurface stormflow and erosion) are all topographically mediated. In remote and data-scarce regions, high resolution DEMs (LiDAR) are often not available, and moderate to course resolution digital elevation models (e.g., SRTM) have difficulty replicating detailed hydrological patterns, especially in relatively flat landscapes. Several surface reconditioning algorithms (e.g., Smoothing) and "Stream burning" techniques (e.g., Agree or ANUDEM), in conjunction with representation of the known stream networks, have been used to improve DEM performance in replicating known hydrology. Detailed stream network data are not available at regional and national scales, but can be derived at local scales from remotely-sensed data. This research explores the implication of high resolution stream network data derived from Google Earth images for DEM hydrological correction, instead of using course resolution stream networks derived from topographic maps. The accuracy of implemented method in producing hydrological-efficient DEMs were assessed by comparing the hydrological parameters derived from modified DEMs and limited high-resolution airborne LiDAR DEMs. The degree of modification is dominated by the method used and availability of the stream network data. Although stream burning techniques improve DEMs hydrologically, these techniques alter DEM characteristics that may affect catchment boundaries, stream position and length, as well as secondary terrain derivatives (e.g., slope, aspect). Modification of a DEM to better reflect known hydrology can be useful, however, knowledge of the magnitude and spatial pattern of the changes are required before using a DEM for subsequent analyses.

  10. The application of time-lapse photography for the observation of snow processes in mountainous catchments

    NASA Astrophysics Data System (ADS)

    Garvelmann, J.; Pohl, S.; Weiler, M.

    2012-04-01

    For the forecast of snowmelt flood events in mountainous catchments it is very important to know the spatial distribution and temporal evolution of the snowcover. Topography and vegetation have the most important influence on the spatio-temporal variability of the snowcover. In order to accomplish a continuous observation of the quantity and the status of the snowcover, an extensive measurement network consisting of numerous standalone snow and meteorological sensors and time-lapse photography was established in three catchments in the Black Forest, a typical mid latitude medium elevation mountain range. Catchments with different topographic characteristic and areal extent were specifically chosen for this study. Within the catchments, a stratified sampling design was used to cover a wide range of altitudes and exposures. In order to investigate the influence of a vegetation cover on the snow processes beneath sensors and cameras have been installed under the forest canopy and on adjacent open field sites, respectively. In the presented study the application of spatially distributed time-lapse cameras for the observation of snow processes and snowcover properties at the catchment scale will be discussed. Image analysis software was applied to extract information about snowdepth, snow albedo and canopy interception from the digital images. A measurement scale with a black/white board was installed in the focus of every camera to allow a determination of the snowdepth at every camera location while the black/white board was used to provide a white balance for the albedo estimation. The albedo provides important information about the status of the snowcover and its temporal evolution is a crucial factor for the snowmelt energy balance. Furthermore the time-lapse images provided a continuous observation of the forest canopy allowing the estimation of the interception efficiency and the temporal evolution of the snow interception for different topographic situations

  11. A MULTIDISCIPLINARY APPROACH TO STORMWATER MANAGEMENT AT THE catchment SCALE

    EPA Science Inventory

    Stormwater runoff from extensive impervious surfaces in urban and suburban areas has led to human safety risks and stream ecosystem impairment, triggering an interest in catchment-scale retrofit stormwater management. Such stormwater management is of multidisciplinary relevance, ...

  12. How does spatial variability of climate affect catchment streamflow predictions?

    EPA Science Inventory

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distribute...

  13. The random walk of tracers through river catchments

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-08-01

    River catchments play critical roles in regional economies and in the global economy. In addition, rivers carry large volumes of nutrients, pollutants, and several other forms of tracers into the ocean. An intricate system of pathways and channels, both on the surface and in the subsurface of catchments, allows rivers to carry large volumes of tracers. However, scientists do not yet fully understand how pollutants and other tracers travel through the intricate web of channels in the catchment areas of rivers. In a new study, Cvetkovic et al show that the travel path of tracers through channels can be modeled as a random walk, which is mathematically similar to the path an animal would trace when foraging. Previous studies have applied the random walk approach to understand the behavior of fluids flowing through aquifers and soils but not to model the transport mechanism of tracers that travel passively with water flowing through catchments.

  14. Causal Relationships Among Time Series of the Lange Bramke Catchment (Harz Mountains, Germany)

    NASA Astrophysics Data System (ADS)

    Aufgebauer, Britta; Hauhs, Michael; Bogner, Christina; Meesenburg, Henning; Lange, Holger

    2016-04-01

    Convergent Cross Mapping (CCM) has recently been introduced by Sugihara et al. for the identification and quantification of causal relationships among ecosystem variables. In particular, the method allows to decide on the direction of causality; in some cases, the causality might be bidirectional, indicating a network structure. We extend this approach by introducing a method of surrogate data to obtain confidence intervals for CCM results. We then apply this method to time series from stream water chemistry. Specifically, we analyze a set of eight dissolved major ions from three different catchments belonging to the hydrological monitoring system at the Bramke valley in the Harz Mountains, Germany. Our results demonstrate the potentials and limits of CCM as a monitoring instrument in forestry and hydrology or as a tool to identify processes in ecosystem research. While some networks of causally linked ions can be associated with simple physical and chemical processes, other results illustrate peculiarities of the three studied catchments, which are explained in the context of their special history.

  15. Automatic set up of SHETRAN for catchments in Great Britain

    NASA Astrophysics Data System (ADS)

    Lewis, Elizabeth; Kilsby, Chris; Fowler, Hayley

    2014-05-01

    Physically-based spatially-distributed (PBSD) models may provide a robust framework for simulating catchment processes in ungauged catchments and under climatic variability. However, they are often overlooked in catchment studies in favour of their conceptual or lumped counterparts. This is because conceptual models are easy and rapid to set up, and can be finely tuned using historic data to give excellent simulation results. On the other hand PBSD models, such as SHETRAN developed at Newcastle University, require much more input data and take weeks or months to set up. To overcome these problems and to promote the use of SHETRAN, this project has set up an easy-to-use, accessible system of hydrological models across Great Britain to be used for both catchment scale studies and countrywide analysis of river flows under present and future conditions. An interface for this system has been developed to make the usually long and tedious setup of PBSD models quick and easy. A non-expert user can now set up a robust and reliable model for a catchment within Great Britain within 10 seconds, a process which would usually take weeks. The user can select a catchment from one of the 1457 boundaries identified in the National River Flow Archive, or they can upload their own catchment boundary as a shapefile. The system therefore has great flexibility for use in setting up models of gauged and ungauged catchments. PBSD models require a lot of data (DEM, geology, soil, land cover), often available in only an inappropriate format. The data behind this system is freely accessible under an academic licence and downloadable from various publicly funded bodies. These data layers have been converted into the correct format for use with SHETRAN, which is also freely available and is provided with every model set up.

  16. Rainfall, runoff and sediment transport in a Mediterranean mountainous catchment.

    PubMed

    Tuset, J; Vericat, D; Batalla, R J

    2016-01-01

    The relation between rainfall, runoff, erosion and sediment transport is highly variable in Mediterranean catchments. Their relation can be modified by land use changes and climate oscillations that, ultimately, will control water and sediment yields. This paper analyses rainfall, runoff and sediment transport relations in a meso-scale Mediterranean mountain catchment, the Ribera Salada (NE Iberian Peninsula). A total of 73 floods recorded between November 2005 and November 2008 at the Inglabaga Sediment Transport Station (114.5 km(2)) have been analysed. Suspended sediment transport and flow discharge were measured continuously. Rainfall data was obtained by means of direct rain gauges and daily rainfall reconstructions from radar information. Results indicate that the annual sediment yield (2.3 t km(-1) y(-1) on average) and the flood-based runoff coefficients (4.1% on average) are low. The Ribera Salada presents a low geomorphological and hydrological activity compared with other Mediterranean mountain catchments. Pearson correlations between rainfall, runoff and sediment transport variables were obtained. The hydrological response of the catchment is controlled by the base flows. The magnitude of suspended sediment concentrations is largely correlated with flood magnitude, while sediment load is correlated with the amount of direct runoff. Multivariate analysis shows that total suspended load can be predicted by integrating rainfall and runoff variables. The total direct runoff is the variable with more weight in the equation. Finally, three main hydro-sedimentary phases within the hydrological year are defined in this catchment: (a) Winter, where the catchment produces only water and very little sediment; (b) Spring, where the majority of water and sediment is produced; and (c) Summer-Autumn, when little runoff is produced but significant amount of sediments is exported out of the catchment. Results show as land use and climate change may have an important

  17. Emergent Archetype Hydrological-Biogeochemical Response Patterns in Heterogeneous Catchments

    NASA Astrophysics Data System (ADS)

    Jawitz, J. W.; Gall, H. E.; Rao, P.

    2013-12-01

    What can spatiotemporally integrated patterns observed in stream hydrologic and biogeochemical signals generated in response to transient hydro-climatic and anthropogenic forcing tell us about the interactions between spatially heterogeneous soil-mediated hydrological and biogeochemical processes? We seek to understand how the spatial structure of solute sources coupled with hydrologic responses affect observed concentration-discharge (C-Q) patterns. These patterns are expressions of the spatiotemporal structure of solute loads exported from managed catchments, and their likely ecological consequences manifested in receiving water bodies (e.g., wetlands, rivers, lakes, and coastal waters). We investigated the following broad questions: (1) How does the correlation between flow-generating areas and biogeochemical source areas across a catchment evolve under stochastic hydro-climatic forcing? (2) What are the feasible hydrologic and biogeochemical responses that lead to the emergence of the observed archetype C-Q patterns? and; (3) What implications do these coupled dynamics have for catchment monitoring and implementation of management practices? We categorize the observed temporal signals into three archetypical C-Q patterns: dilution; accretion, and constant concentration. We introduce a parsimonious stochastic model of heterogeneous catchments, which act as hydrologic and biogeochemical filters, to examine the relationship between spatial heterogeneity and temporal history of solute export signals. The core concept of the modeling framework is considering the types and degree of spatial correlation between solute source zones and flow generating zones, and activation of different portions of the catchments during rainfall events. Our overarching hypothesis is that each of the archetype C-Q patterns can be generated by explicitly linking landscape-scale hydrologic responses and spatial distributions of solute source properties within a catchment. The model

  18. Dispatch centres: what is the right population catchment size?

    PubMed

    Dami, Fabrice; Fuchs, Vincent; Hugli, Olivier

    2015-04-09

    Literature on medical dispatch is growing, focusing mainly on efficiency (under and overtriage) and dispatch-assisted CPR. But the issue of population catchment size, functional costs and rationalization is rarely addressed. If we can observe a trend toward a decreasing number of dispatch centres in many European countries, there is today no evidence on what is the right catchment size to reach the best balance between quality of services and costs.

  19. Study of Beijiang catchment flash-flood forecasting model

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Li, J.; Huang, S.; Dong, Y.

    2015-05-01

    Beijiang catchment is a small catchment in southern China locating in the centre of the storm areas of the Pearl River Basin. Flash flooding in Beijiang catchment is a frequently observed disaster that caused direct damages to human beings and their properties. Flood forecasting is the most effective method for mitigating flash floods, the goal of this paper is to develop the flash flood forecasting model for Beijiang catchment. The catchment property data, including DEM, land cover types and soil types, which will be used for model construction and parameter determination, are downloaded from the website freely. Based on the Liuxihe Model, a physically based distributed hydrological model, a model for flash flood forecasting of Beijiang catchment is set up. The model derives the model parameters from the terrain properties, and further optimized with the observed flooding process, which improves the model performance. The model is validated with a few observed floods occurred in recent years, and the results show that the model is reliable and is promising for flash flood forecasting.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  1. 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

    Climatic conditions impact biotransformation and transfer of solutes. Therefore, they modify solute emissions in streams. Studying these modifications requires long term and detailed monitoring of both internal processes and river loads, which are rarely combined. The Kervidy-Naizin catchment, implemented in 1993, is part of the French network of catchment for environmental research (SOERE RBV, focused on the Critical Zone). It is an intensive agricultural catchment located in a temperate climate in Western France (Brittany) (Molenat et al., 2008; Morel et al., 2009). It presents shallow aquifers due to impervious bedrock. Both hydrology and water chemistry are monitored with a daily time step since 2000-01, as well as possible explanatory data (land use, meteorology, etc.). Concentrations in major anions in this catchment are extremely high, which make people call it a "saturated" catchment. We identified annual patterns for chloride, sulphate, dissolved organic and inorganic carbon and nitrate concentration variations. First, we considered the complete set of concentration data as function of the time. From that, we foresaw 3 cyclic temporal patterns. Then, from representing the concentrations as function of meteorological parameters, intra-annual hysteretic variations and their inter-annual variations were clearly identified. Our driving question is to know if and how climatic conditions are responsible for variations of the patterns in and between years. In winter, i.e. rainy and cold period, rainfall is closely linked to discharge because of a direct recharge to the shallow groundwater. Reversely, in transition periods (spring and fall) and hot periods, both rainfall and temperature influences discharge in relation to their range of variations. Moreover, biological processes, driven by temperature and wetness, also act during these periods. On the whole, we can emphasize the specificity of water chemistry patterns for each element. Noticeable differences

  2. Catchment controls on soil moisture dynamics: from site-specific hysteresis in event responses to temporal stability of patterns

    NASA Astrophysics Data System (ADS)

    Hassler, Sibylle K.; Weiler, Markus; Blume, Theresa

    2015-04-01

    Understanding soil moisture dynamics is a prerequisite for predicting hydrological response at the hillslope and catchment scale. Soil moisture is not only determined by its input characteristics such as rainfall, its redistribution by vegetation and evapotranspiration. Catchment characteristics resulting from the interplay of geology, topography, land cover and associated soil hydraulic properties also affect the distribution, storage and transport of water in the vadose zone. Successful process predictions and appropriate hydrological model structures thus rely on a good representation of soil moisture patterns and dynamics and benefit from insights into their dependence on catchment characteristics. In a unique measurement setup at the CAOS hydrological observatory in Luxemburg (http://www.caos-project.de) we record hydro-meteorological variables at 45 sensor cluster sites. These sites are distributed across the mesoscale Attert catchment and cover three different geological units (schist, marls and sandstone), two types of land use (forest and grassland), different topographical positions (up- and downslope with north- and south-facing aspects as well as plateau and floodplain locations). At each sensor cluster, each covering approximately an area of 30 m², soil moisture is measured in three profiles at three different depths, in piezometers groundwater levels are recorded, and rain gauges collect throughfall or gross precipitation. At near-stream locations we also measure stream water levels. This extensive sensor network enables us to study the influence of geology, land use and topography on soil moisture dynamics. In this study we focus on short-term hysteretic responses related to individual rainfall events and on longer-term temporal stability of soil moisture patterns. Similarities in the hysteresis loops of rainfall/soil moisture, soil moisture/groundwater levels and soil moisture/stream water levels can give some indication of the dominant catchment

  3. Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

    NASA Astrophysics Data System (ADS)

    Hector, Basile; Séguis, Luc; Hinderer, Jacques; Cohard, Jean-Martial; Wubda, Maxime; Descloitres, Marc; Benarrosh, Nathalie; Boy, Jean-Paul

    2015-10-01

    In basement catchments of subhumid West Africa, base flow is the main component of annual streamflow. However, the important heterogeneity of lithology hinders the understanding of base flow generation processes. Since these processes are linked with water storage changes (WSCs) across the catchment, we propose the use of hybrid gravity data in addition to neutron probe-derived water content and water levels to monitor spatiotemporal WSC of a typical crystalline basement headwater catchment (16 ha) in Benin. WSC behaviors are shown to provide insights into hydrological processes in terms of water redistribution toward the catchment outlet. Hybrid gravimetry produces gravity change observations from time-lapse microgravity surveys coupled with gravity changes monitored at a base station using a superconducting gravimeter and/or an absolute gravimeter. A dense microgravity campaign (70 surveys of 14 stations) covering three contrasted years was set up with a rigorous protocol, leading to low uncertainties (<2.5 μGal) on station gravity determinations (with respect to the network reference station). Empirical orthogonal function analyses of both gravity changes and WSCs from neutron probe data show similar spatial patterns in the seasonal signal. Areas where storage and water table show a capping behavior (when data reach a plateau during the wet season), suggesting threshold-governed fast subsurface redistribution, are identified. This observed storage dynamics, together with geological structures investigated by electrical resistivity tomography and drill log analysis, make it possible to derive a conceptual model for the catchment hydrology.

  4. Rainfall–Runoff Simulations to Assess the Potential of SuDS for Mitigating Flooding in Highly Urbanized Catchments

    PubMed Central

    Jato-Espino, Daniel; Charlesworth, Susanne M.; Bayon, Joseba R.; Warwick, Frank

    2016-01-01

    Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall–runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network. PMID:26805864

  5. Overland flow computations in urban and industrial catchments from direct precipitation data using a two-dimensional shallow water model.

    PubMed

    Cea, L; Garrido, M; Puertas, J; Jácome, A; Del Río, H; Suárez, J

    2010-01-01

    This paper presents the experimental validation and the application to a real industrial catchment of a two-dimensional depth-averaged shallow water model used for the computation of rainfall-runoff transformation from direct precipitation data. Instead of using the common approach in flood inundation modelling, which consists in computing the water depth and velocity fields given the water discharge, in this study the rainfall intensity is imposed directly in the model, the surface runoff being generated automatically. The model considers infiltration losses simultaneously with flow simulation. Gullies are also included in the model, although the coupling between the surface runoff and the sewer network is not considered. Experimental validation of the model is presented in several simplified laboratory configurations of urban catchments, in which the surface runoff has been measured for different hyetographs. The application to a real industrial catchment includes a sewer network flow component, which is solved with the SWMM model. The numerical predictions of the discharge hydrograph generated by a 12 hours storm event are compared with field measurements, providing encouraging results.

  6. Rainfall-Runoff Simulations to Assess the Potential of SuDS for Mitigating Flooding in Highly Urbanized Catchments.

    PubMed

    Jato-Espino, Daniel; Charlesworth, Susanne M; Bayon, Joseba R; Warwick, Frank

    2016-01-21

    Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall-runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network.

  7. Palaeo-fluvial origin for Jakobshavn Isbrae catchment

    NASA Astrophysics Data System (ADS)

    Cooper, Michael; Michaelides, Katerina; Siegert, Martin; Bamber, Jonathan

    2016-04-01

    Subglacial topography exerts strong controls on ice dynamics, influencing the nature of ice flow, and modulating the distribution of basal waters and sediment. Bed geometry can provide a long-term record of geomorphic processes, allowing insight into landscape evolution, the origin of which, in some cases, can pre-date ice sheet inception. Here, we present evidence from ice-penetrating radar data for a large dendritic drainage network, radiating inland from Jakobshavn Isbrae, Greenland's largest outlet glacier. The size of the drainage basin is ~450,000 km-squared, comparable with that of the Ohio River in the United States, and accounts for ~20% of the land area of Greenland. Topographic, and basin morphometric analysis of isostatically compensated (ice-free) bedrock topography suggests that this catchment pre-dates ice sheet inception (~3.5 Ma), and will have been instrumental in influencing flow from the island's interior to the margin. The geological setting, and glacial history of Greenland lends itself well to the preservation of such landscapes; the island is dominated by erosion-resistant, Precambrian crystalline rocks with few sedimentary deposits, and has only been extensively ice-covered for ~3.5 million years (Ma). Despite this, most analysis of subglacial geomorphology, and of 'pre-glacial' landscapes, has been focused on Antarctica (e.g. the Ellsworth Subglacial Highlands and, 'pre-glacial erosional surfaces' of the West Antarctic Ice Sheet (WAIS)), with little consideration for such associations in Greenland. However, a large subglacial 'mega-canyon' in northern Greenland, thought to of palaeo-fluvial origin, has recently been discovered.

  8. New insights in catchment processes via distributed soil moisture measurements and 3D hydrological modeling

    NASA Astrophysics Data System (ADS)

    Bogena, H. R.; Sciuto, G.; Rosenbaum, U.; Herbst, M.; Huisman, J. A.; Vereecken, H.; Diekkrueger, B.

    2010-12-01

    Hydrological analysis is often limited by the number of data available. Usually, discharge data and only little point information concerning soil moisture status are available. This might give a good representation of the temporal variability of runoff, but it does not provide insights into the spatial dynamics of soil moisture and water fluxes within the catchment. The small forested Wüstebach catchment (~27 ha) has been instrumented with a wireless sensor network consisting of 150 nodes and more than 1200 soil moisture sensors in the framework of the Transregio32 and the Helmholtz initiative TERENO (Terrestrial Environmental Observatories) [1]. This unique data set provides a consistent picture of the hydrological status of the catchment in a high spatial and temporal resolution. We present first results of a geostatistical analysis of the data and an application of the integrated surface/subsurface 3D finite element model HydroGeoSphere model to investigate the scale dependency of the temporal dynamics of soil moisture patterns. A variogram analysis showed that the sum of the sub-scale variability and the measurement error is close to time-invariant. Wet situations showed smaller spatial variability, which is attributed to saturated soil moisture, which poses an upper limit and is typically not strongly variable in headwater catchments with relatively homogeneous soil. The spatiotemporal variability in soil moisture at 50 cm depth was significantly lower than at 5 and 20 cm. This finding indicates that the considerable variability of the top soil is buffered deeper in the soil due to root water uptake, lateral and vertical water fluxes. Topographic features showed the strongest correlation with soil moisture during dry periods, indicating that the control of topography on the soil moisture pattern depends on the soil water status. The temporal patterns of runoff discharge were reproduced by the HydroGeoSphere model in a satisfying way. The observed soil

  9. A catchment engineering approach to nutrient and sediment management: A case study from the UK

    NASA Astrophysics Data System (ADS)

    Barber, N. J.; Quinn, P. F.; Bathurst, J. C.; Jonczyk, J.

    2011-12-01

    A rural catchment in the UK is being monitored in a multi-scaled, nested experiment to identify the parts of the landscape that contribute Diffuse Water Pollution from Agriculture (DWPA) by measuring phosphorus (P), nitrate (N) and suspended sediment (SS) losses across the river network. Results have been analysed spatially and temporally, with a focus on storm events and high flows, and it is conceptualised that the majority of polluted runoff is delivered via a relatively low number of diffuse flow pathways. It is therefore hypothesised that by targeting these distributed point sources and 'engineering' catchments, it is possible to mitigate the impacts of DWPA cost effectively without compromising agricultural productivity. Runoff Attenuation Features (RAFs) are examples of soft engineering measures, including small ponds, wetlands, sediment traps, filters, which are designed to intercept polluted flow pathways in order to slow, store and filter the runoff. A number of RAFs have been designed and constructed and their ability to trap SS and remove and recover P and N has been quantified. The interventions have demonstrated the ability to substantially reduce certain pollutant concentrations (up to 90% SS and 65% total P), particularly during storm events, as well as attenuating flood flows and providing wider ecosystem services. RAFs function most effectively when applied to farm ditches and small streams, relatively close to pollution sources, and we propose that this is the most cost effective Best Management Practice methodology. Our work has shown, however, that P-rich fine sediment (<0.45μm) is difficult to remove from runoff when relying on settlement alone. Therefore, a series of physical filter features have been developed, comprising a range of filter media installed in ponds and ditch networks to test their efficacy. Catchment engineering provides the ability to sustainably manage water quality and quantity using a proactive, interventionist approach

  10. Demonstrating the viability and value of community-based monitoring schemes in catchment science

    NASA Astrophysics Data System (ADS)

    Starkey, Eleanor; Parkin, Geoff; Quinn, Paul; Large, Andy

    2016-04-01

    Hydrological catchments are complex systems which need to be monitored over time in order to characterise their behaviour on a local level, model, implement mitigation measures and meet policy targets. Despite hydrometric monitoring techniques being well developed, data is often inadequate within rural areas. Local knowledge and experiences are also vital sources of information in this sector but they are not routinely harvested. Long-term evidence is required to provide stakeholders with confidence and innovation is required to fully engage with and inform the public. Citizen science and volunteered geographical information (VGI) projects are encouraging volunteers to participate in crowdsourcing activities and generate new knowledge, but they have not been fully investigated within catchment science. A citizen science approach has therefore been implemented within the 42km2 Haltwhistle Burn catchment (northern England) using effective engagement techniques. This catchment responds rapidly, experiences flash flood events, and like many, it does not benefit from any traditional monitoring equipment. Participation levels confirm that members of the public do want to monitor their local water environment, with flooding being a key driver. Regular 'River Watch' volunteers and passers-by are sharing their knowledge and monitoring rainfall, river levels, water quality parameters, sediment issues, flood events and performance of flood risk management features. This has enabled a variety of low-cost data collection and submission tools to be tested over a two year period. Training has encouraged good quality data to be collected and volunteers are ready to capture meaningful information during unexpected flood events. Although volunteers are capable of collecting quantitative information, photographs and videos are submitted more readily. Twitter has also been used to share real-time observations successfully. A traditional monitoring network has been running in parallel

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

    PubMed

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

    2002-12-01

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

  12. 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

  13. Modeling seasonal export and retention of nutrients in european catchments.

    NASA Astrophysics Data System (ADS)

    de Klein, J.

    2003-04-01

    In the abatement of eutrophication of standing waters management of sources and transport of nutrients in river catchments is crucial. However the transport of nitrogen and phosphorus can vary significantly among (sub) catchments as a result of different physical, chemical and biotic factors. Qualitative and quantitative differences in nutrient pathways within catchments hamper the application of common standards and reliable prediction of the effect of nutrient loads. The EU-project BUFFER is set up to provide a tool which describes the relation between catchment properties and activities resulting in nutrient loads on one hand, and the ecological state of the receiving lakes on the other hand. To support this a new model-concept is developed that describes the transport and retention of nutrients in running waters (De Klein, 2002). The calculation requires minimum input data and generates output on a seasonal basis. The model was so far applied to Dutch catchments. This paper presents the extension and verification of the model, based on data of intensively studied catchments within the BUFFER-project. This implies the method can be applied to a wider range of European catchments. Basic model inputs are total annual loads of nutrients from point and diffuse sources to the surface (head) waters. During transport nutrients are retained in the catchment. Retention coefficients vary over the seasons and are calculated from a) residence time, which can be approximated using rainfall data, size of drainage basin and morphological properties b) temperature. The model outputs retention and export from the catchment on a monthly basis, using a set of straightforward formulas. Coefficients are calibrated with a subset of the measured data in an optimization routine, and subsequently verified. The similarity of measured and calculated values was high (r2 > 0.8; p<0.01). With a rather simple calculation method with few input data it is possible to estimate monthly export

  14. Where to measure point rainfall during extreme flash flood events in mountainous catchments?

    NASA Astrophysics Data System (ADS)

    Troch, P. A.; Volkmann, T.; Lyon, S. W.; Gupta, H.

    2009-04-01

    Despite the availability of weather radar data at high spatial (1 km^2) and temporal (5-15 min) resolution, ground-based rain gauges are still needed to accurately estimate storm rainfall input to catchments during flash flood events. This is especially true in mountainous catchments where estimating storm depth and intensity from radar data is more challenging than in flat terrain. Given economical limitations on the number of rain gauges, a long-standing problem in catchment hydrology is where to put the (limited amount of) rain gauges to best capture both storm rainfall depth and temporal variability of storm intensity during extreme events. This study addresses the question whether it is possible to predict the best locations for rain gauge installation given a basin's topography and dominant storm tracks. A network of 40 tipping bucket rain gauges was deployed in the Sabino Canyon catchment near Tucson, AZ, during the summer monsoon season of 2006. An extreme, multi-day rainfall event during 27-31 July 2006 caused record flooding and an unprecedented series of slope failures and debris flows in the Santa Catalina Mountains. Geostatistics (kriging with external drift, KED) was used to combine the tipping bucket rain gauge observations with NEXRAD weather radar to create rasterized rainfall maps with high spatial (1 km^2) and temporal (15 min) resolution over the entire multi-day rainfall event. We use these KED rainfall maps to determine the optimized locations for an installation of 1 up to 4 rain gauges considering all possible subsets of 1 to 4 grid cells over the entire rainfall event. Our optimization method minimizes both the residual percent bias and the coefficient of correlation between the mean areal rainfall obtained using the KED rainfall maps and mean rainfall determined using each subset. This method was applied to the entire record of rainfall observations to identify networks consisting of 1 to 4 rain gauges which represent the

  15. Sub-tropical freshwater storage catchments: major greenhouse gas sinks?

    NASA Astrophysics Data System (ADS)

    Grinham, Alistair; Dunbabin, Matthew

    2013-04-01

    The relatively unstudied catchments and freshwater storages of the sub-tropics represent a potentially important gap in understanding global greenhouse gas cycling. The low number of studies may bias attempts to include this region's contribution to global greenhouse gas cycling, as very few studies have examined the major drivers behind terrestrial and aquatic greenhouse cycling in such sub-tropical areas. In addition, the uncertainty associated in quantifying greenhouse gas emission rates is relatively unknown. This information is crucial to determine whether freshwater storages and their associated catchments are net sources or sinks of greenhouse gas. Here, we present a greenhouse gas audit of the catchment and freshwater storage of Little Nerang Dam to determine the greenhouse gas status of the system as a whole. Little Nerang Dam is a sub-tropical freshwater storage located in Southeast Queensland, Australia. The catchment is in a relatively pristine condition with over 85% native forest remaining dominated by carbon dense Eucalypt species trees. Aquatic surface area is approximately 0.5 km2 in contrast to the terrestrial surface area of 35 km2. This system is an ideal model to investigate drivers behind greenhouse cycling in a relatively undisturbed catchment. A comprehensive field survey was conducted to estimate the major pools of carbon including terrestrial above and belowground fractions as well as the aquatic sediment and water column fractions. Greenhouse rates of emissions and sequestration were monitored over an annual cycle; parameters included tree growth rates, soil respiration, forest litter fall rates and aquatic methane and nitrous oxide fluxes. Results demonstrated the terrestrial carbon pool exceeded the aquatic pool by at least 2 orders of magnitude. When emission and sequestration rates were expressed as CO2 equivalents per unit area catchment sequestration was approximately double that of catchment and storage emissions. When rates were

  16. The Effect of Terrain Aspect on Interannual Variability of Hydrologic Response in Mountainous Catchments in New Mexico

    NASA Astrophysics Data System (ADS)

    Zapata, X.; Troch, P. A.; McIntosh, J. C.; Broxton, P. D.; Brooks, P. D.

    2012-12-01

    The aspect of the land surface in mid and high latitudes control hydrological response through differences in energy fluxes, prevailing winds, snow processes, evaporation and transpiration. In the Valles Caldera National Preserve (VCNP) in northern New Mexico, recent research has shown that north facing terrains accumulate thicker snow packs, the snow cover duration is longer, the soil moisture content is higher and hillslopes have longer water transit times. These findings suggest that catchments with a predominant north facing aspect are expected to have more water available and consequently a different hydrological response than catchments characterized by a different land orientation. This poster presents four years (2008-2011) of hydrological data in the VCNP and shows the hydrological response to interannual climate variability in mountainous catchments draining along different aspects. This investigation focuses on three perennial catchments draining Redondo Peak (3435m): La Jara (LJ; 3.67 km2), History Grove (HG; 2.42 km2) and Upper Jaramillo (UJ; 3.06 km2). The three catchments range in elevation between 2680 m and 3429 m. They share similar topographic characteristics, climate, vegetation and a complex geology. The most predominant north facing catchment is UJ; HG and LJ have both a predominant east facing aspect. This study is based on empirical observations of basin response and it has been carried out by way of monitoring physical amount, intensity and timing of water entering and leaving the catchments using the available meteorological data in the region and the instrumented network installed by the Jemez River Basin and Santa Catalina Mountains Critical Zone Observatory (http://www.czo.arizona.edu/). The climate in the region is semi-arid, continental and highly variable. For the water years (WY) 2008 and 2011 annual precipitation was 86% and 71% below the mean (P=711.5mm), and during WY 2009 and 2010, annual precipitation was 4% and 1% above the

  17. Sediment flux dynamics as fingerprints of catchment rehabilitation: The case of western Rift Valley escarpment of northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Asfaha, Tesfaalem G.; Frankl, Amaury; Haile, Mitiku; Zenebe, Amanuel; Nyssen, Jan

    2015-12-01

    50) (R2 = 0.96, p < 0.01), and with reference to D84 (r84) (R2 = 0.93, p < 0.01). The relationships between event Max10 and event Qp in each catchment were also used to extrapolate the peak discharges that would have prevailed in the first half of the 1980s, and the results showed huge reductions in peak discharges (p < 0.01) as a result of the reforestation interventions. Overall, this study demonstrates that (i) the supply of bedload in steep tropical mountains is determined negatively by forest or vegetation cover and positively by the presence of scar networks in the sloping parts of the catchments and catchment size; (ii) entrainment of the coarsest bedload particles is determined positively by peak discharge, stream power, stream bed roughness, and most strongly by critical shear stress; and (iii) in steep mountain streams where direct measurement of bedload movement is difficult, yet simple in situ measurement of the coarsest bedload particles (Max10) supplied and entrained in each event helps for understanding the dynamics of sediment flux in relation to catchment rehabilitation.

  18. 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

  19. Hydroclimatic changes and drivers in the Sava River Catchment and comparison with Swedish catchments.

    PubMed

    Levi, Lea; Jaramillo, Fernando; Andričević, Roko; Destouni, Georgia

    2015-11-01

    In this study, we investigate long-term hydroclimatic changes and their possible relation to regional changes in climate, land-use and water-use over the twentieth century in the transboundary Sava River Catchment (SRC) in South Eastern Europe. In a hydropower dominated part of the SRC, unlike in an unregulated part, we find increase in average annual evapotranspiration and decrease in temporal runoff variability, which are not readily explainable by observed concurrent climate change in temperature and precipitation and may be more related to landscape-internal change drivers. Among the latter investigated here, results indicate hydropower developments as most closely related to the found hydroclimatic shifts, consistent with previous such indications in studies of Swedish hydropower catchments. Overall, the present results have quantitatively framed the recent history and present state of hydroclimate in the SRC, of relevance for water resources in several countries and for a majority of their populations. This provides a useful basis for further assessment of possible future hydroclimatic changes, under different scenarios of climate change and land/water-use developments in the region.

  20. Stormflow generation: A meta-analysis of field evidence from small, forested catchments

    NASA Astrophysics Data System (ADS)

    Barthold, Frauke K.; Woods, Ross A.

    2015-05-01

    Combinations of runoff characteristics are commonly used to represent distinct conceptual models of stormflow generation. In this study, three runoff characteristics: hydrograph response, time source of runoff water, and flow path are used to classify catchments. Published data from the scientific literature are used to provide evidence from small, forested catchments. Each catchment was assigned to one of the eight conceptual models, depending on the combination of quick/slow response, old/new water, and overland/subsurface flow. A standard procedure was developed to objectively diagnose the predominant conceptual model of stormflow generation for each catchment and assess its temporal and spatial support. The literature survey yielded 42 catchments, of which 30 catchments provide a complete set of qualitative runoff characteristics resulting in one of the eight conceptual models. The majority of these catchments classify as subsurface flow path dominated. No catchments were found for conceptual models representing combinations of quick response-new water-subsurface flow (SSF), slow-new-SSF, slow-old-overland flow (OF) nor new-slow-OF. Of the 30 qualitatively classified catchments, 24 provide a complete set of quantitative measures. In summary, the field support is strong for 19 subsurface-dominated catchments and is weak for 5 surface flow path dominated catchments (six catchments had insufficient quantitative data). Two alternative explanations exist for the imbalance of field support between the two flow path classes: (1) the selection of research catchments in past field studies was mainly to explain quick hydrograph response in subsurface dominated catchments; (2) catchments with prevailing subsurface flow paths are more common in nature. We conclude that the selection of research catchments needs to cover a wider variety of environmental conditions which should lead to a broader, and more widely applicable, spectrum of resulting conceptual models and process

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

    PubMed

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

    2011-06-01

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

  2. Hydrological drought severity explained by climate and catchment characteristics

    NASA Astrophysics Data System (ADS)

    Van Loon, A. F.; Laaha, G.

    2015-07-01

    Impacts of a drought are generally dependent on the severity of the hydrological drought event, which can be expressed by streamflow drought duration or deficit volume. For prediction and the selection of drought sensitive regions, it is crucial to know how streamflow drought severity relates to climate and catchment characteristics. In this study we investigated controls on drought severity based on a comprehensive Austrian dataset consisting of 44 catchments with long time series of hydrometeorological data (on average around 50 year) and information on a large number of physiographic catchment characteristics. Drought analysis was performed with the variable threshold level method and various statistical tools were applied, i.e. bivariate correlation analysis, heatmaps, linear models based on multiple regression, varying slope models, and automatic stepwise regression. Results indicate that streamflow drought duration is primarily controlled by storage, quantified by the Base Flow Index or by a combination of catchment characteristics related to catchment storage and release, e.g. geology and land use. Additionally, the duration of dry spells in precipitation is important for streamflow drought duration. Hydrological drought deficit, however, is governed by average catchment wetness (represented by mean annual precipitation) and elevation (reflecting seasonal storage in the snow pack and glaciers). Our conclusion is that both drought duration and deficit are governed by a combination of climate and catchment control, but not in a similar way. Besides meteorological forcing, storage is important; storage in soils, aquifers, lakes, etc. influences drought duration and seasonal storage in snow and glaciers influences drought deficit. Consequently, the spatial variation of hydrological drought severity is highly dependent on terrestrial hydrological processes.

  3. Isotope tracers in catchment hydrology: How far can we go?

    NASA Astrophysics Data System (ADS)

    McDonnell, J. J.

    2009-05-01

    The use of stable isotopes as tracers of water has fundamentally changed the way that we view catchment hydrology. Tracer-based mass balance mixing studies in the past decades have revealed that most of the water comprising the storm hydrograph (in humid areas) is dominated by pre-event water. Furthermore, using the convolution integral approach to long term isotopic time series, studies have revealed a wide range of streamwater residence times (focused mostly on baseflow), from months to decades, but with most on the order of 1-3 years. These findings have now matured to the point where such information is informing rainfall- runoff model testing. As a result, stable isotope tracers offer new and orthogonal data measures for rejecting model structures. Similarly, scaling relations detected in streamwater residence time data offer hope for a new pathway to understand and quantify multi-scale catchment response patterns. So how far can we go with stable isotope tracers in catchment hydrology? Here I offer some suggestions on new research avenues that capitalize on the use of laser spectrometers and how the resulting increased sample frequencies in time and space (with laser specs in the lab and in the field) may offer new hydrological insights. Examples are given that apply to ecohydrological studies in catchments to resolve how vegetation and streams appear to return different pools of water to the hydrosphere; virtual experiments with catchment models to assess the fundamental controls on catchment residence time distribution; multi-tracer approaches to streamwater residence time to reconcile the striking differences in residence time estimates between oxygen-18 and tritium; and labeled isotope additions at the plot, hillslope and catchment scale under controlled input conditions for resolving the age, origin and pathway of flow.

  4. A catchment-wide assessment of bed sediment metal concentrations in the first industrial city

    NASA Astrophysics Data System (ADS)

    Hurley, Rachel; Rothwell, James; Woodward, Jamie

    2016-04-01

    Manchester is often heralded as the 'first industrial city'. Rapid industrialisation in the 18th and 19th centuries saw vast quantities of fine-grained sediments (e.g. boiler ash and cinders) and contaminants (e.g. dyes, bleaches, and chemicals) deposited into the river channels of the Irwell and Mersey in a manner largely unchecked until the 1970s. Although water quality has improved in recent decades, there is a paucity of information on fluvial sediment quality and the extent to which a legacy of historical contamination persists in the contemporary river network. Forty five sites were sampled across the Irwell and Mersey catchments during low flow conditions in spring/summer 2015. Fine-grained bed sediment was collected using the Lambert and Walling (1988) method. Wet sieving was used to isolate the <63 μm fraction for geochemical analysis. Heavy metal concentrations were obtained via XRF with a particular focus on As, Cr, Cu, Pb and Zn. In order to explore controls on sediment-associated metal concentrations, additional characteristics of the bed sediment were also investigated, including particle size and organic matter content. Enrichment factors, based on mean concentrations obtained from pre-industrial floodplain deposits, were calculated. The enrichment factors reveal severe or very severe metal contamination across the whole catchment, including the headwater basins. Relationships between bed sediment quality and hotspots of historic industrial activity have been examined - these reveal complex spatial patterns associated with the high number and variety of historic contaminant inputs. These data form the first baseline assessment and will be used within a larger project investigating the impact of extreme hydrological events on bed sediment quality and transfer in these catchments.

  5. Spatial and Temporal Variation of Vertical Motions in the Congo River Catchment

    NASA Astrophysics Data System (ADS)

    Rogers, E. P.; White, N.; Jones, S.

    2005-12-01

    Africa's 'basin and swell' topography is thought to be dynamically supported by mantle convection and correlates closely with long wavelength free-air gravity anomalies, which can be regarded as a proxy for the convective pattern. Seismic tomographic studies reveal a region of slow seismic velocity beneath sub-equatorial Africa. This region broadly correlates with a zone of anomalously high elevation, known as the 'African Superswell' that stretches from the South Atlantic Ocean across Africa to Afar. More recently temporal parameters such as uplift rate have been considered in dynamic topography modeling. However, theoretical predictions of dynamic topography have not been carefully tested against observations. The Congo River Catchment is of particular interest as its large catchment area drains from both negative and positive long wavelength free air gravity. The recent availability of global high-resolution topographic data (e.g. SRTM 90 meter) allows for detailed studies of geomorphological features of inaccessible areas such as the Congo Basin. DEMs show that drainage along the southern edge of the Congo River Catchment incises into a smooth, low relief surface. This surface slopes northwards from elevations of 1500m to 700m. Knickpoints on river profiles indicate that the drainage network is immature and may have experienced a recent change in base level. The low-relief surface represents the top of a group of fluviatile sediments, known as the sable ocres deposited in an aggrading environment. Topography of this surface correlates with long wavelength free-air gravity anomalies and is caused by mantle convection. This correlation is evident in an admittance analysis of gravity and topography in the frequency domain. The geology and geomorphology in this region can be used as a further test of uplift rates predicted from seismic tomographic data.

  6. Nitrate contamination of groundwater in the catchment of Goczałkowice reservoir

    NASA Astrophysics Data System (ADS)

    Czekaj, Joanna; Witkowski, Andrzej J.

    2014-05-01

    Goczałkowice dammed reservoir (area - 26 km2 , volume - 100 million m3 at a typical water level) is a very important source of drinking water for Upper Silesian agglomeration. At the catchment of the reservoir there are many potential sources of groundwater pollution (agriculture, bad practices in wastewater management, intensive fish farming). Thus local groundwater contamination, mainly by nitrogen compounds. The paper presents groundwater monitoring system and preliminary results of the research carried on at Goczałkowice reservoir and its catchment in 2010 - 2014 within the project "Integrated system supporting management and protection of dammed reservoir (ZiZoZap)'. The main objective for hydrogeologists in the project is to assess the role of groundwater in total water balance of the reservoir and the influence of groundwater on its water quality. During research temporal variability of groundwater - surface water exchange has been observed. Monitoring Network of groundwater quality consists of 22 observation wells (nested piezometers included) located around the reservoir - 13 piezometers is placed in two transects on northern and southern shore of reservoir. Sampling of groundwater from piezometers was conducted twice - in autumn 2011 and spring 2012. Maximum observed concentrations of nitrate, nitrite and ammonium were 255 mg/L, 0,16 mg/L and 3,48 mg/L, respectively. Surface water in reservoir (8 points) has also been sampled. Concentrations of nitrate in groundwater are higher than in surface water. Nitrate and ammonium concentrations exceeding standards for drinking water were reported in 18% and 50% of monitored piezometers, respectively. High concentration of nitrate (exceeding more than 5 times maximal admissible concentration) have been a significant groundwater contamination problem in the catchment of the reservoir. Periodically decrease of surface water quality is possible. Results of hydrogeological research indicate substantial spatial

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  8. Runoff sources and flowpaths in a partially burned, upland boreal catchment underlain by permafrost

    USGS Publications Warehouse

    Koch, Joshua C.; Kikuchi, Colin P.; Wickland, Kimberly P.; Schuster, Paul

    2014-01-01

    Boreal soils in permafrost regions contain vast quantities of frozen organic material that is released to terrestrial and aquatic environments via subsurface flowpaths as permafrost thaws. Longer flowpaths may allow chemical reduction of solutes, nutrients, and contaminants, with implications for greenhouse gas emissions and aqueous export. Predicting boreal catchment runoff is complicated by soil heterogeneities related to variability in active layer thickness, soil type, fire history, and preferential flow potential. By coupling measurements of permeability, infiltration potential, and water chemistry with a stream chemistry end member mixing model, we tested the hypothesis that organic soils and burned slopes are the primary sources of runoff, and that runoff from burned soils is greater due to increased hydraulic connectivity. Organic soils were more permeable than mineral soils, and 25% of infiltration moved laterally upon reaching the organic-mineral soil boundary on unburned hillslopes. A large portion of the remaining water infiltrated into deeper, less permeable soils. In contrast, burned hillslopes displayed poorly defined soil horizons, allowing rapid, mineral-rich runoff through preferential pathways at various depths. On the catchment scale, mineral/organic runoff ratios averaged 1.6 and were as high as 5.2 for an individual storm. Our results suggest that burned soils are the dominant source of water and solutes reaching the stream in summer, whereas unburned soils may provide longer term storage and residence times necessary for production of anaerobic compounds. These results are relevant to predicting how boreal catchment drainage networks and stream export will evolve given continued warming and altered fire regimes.

  9. River nutrient loads and catchment size

    USGS Publications Warehouse

    Smith, S.V.; Swaney, D.P.; Buddemeier, R.W.; Scarsbrook, M.R.; Weatherhead, M.A.; Humborg, Christoph; Eriksson, H.; Hannerz, F.

    2005-01-01

    We have used a total of 496 sample sites to calibrate a simple regression model for calculating dissolved inorganic nutrient fluxes via runoff to the ocean. The regression uses the logarithms of runoff and human population as the independent variables and estimates the logarithms of dissolved inorganic nitrogen and phosphorus loading with R 2 values near 0.8. This predictive capability is about the same as has been derived for total nutrient loading with process-based models requiring more detailed information on independent variables. We conclude that population and runoff are robust proxies for the more detailed application, landscape modification, and in-stream processing estimated by more process-based models. The regression model has then been applied to a demonstration data set of 1353 river catchments draining to the sea from the North American continent south of the Canadian border. The geographic extents of these basins were extracted from a 1-km digital elevation model for North America, and both runoff and population were estimated for each basin. Most of the basins (72% of the total) are smaller than 103 km2, and both runoff and population density are higher and more variable among small basins than among larger ones.While total load to the ocean can probably be adequately estimated from large systems only, analysis of the geographic distribution of nutrient loading requires consideration of the small basins, which can exhibit significant hydrologic and demographic heterogeneity between systems over their range even within the same geographic region. High-resolution regional and local analysis is necessary for environmental assessment and management. ?? Springer 2005.

  10. 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

  11. Carbon redistribution by erosion processes in an intensively disturbed catchment

    NASA Astrophysics Data System (ADS)

    Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

    2016-04-01

    Understanding how organic carbon moves with sediments along the fluvial system is crucial to close catchment scale carbon budgets. Especially challenging is the analysis of organic carbon dynamics during fluvial transport in heterogeneous, fragile and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale organic carbon redistribution by lateral flows in extreme Mediterranean environmental conditions from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, shallow soils, and highly disturbed by agricultural terraces, land levelling, reforestations and construction of check-dams. To increase understanding of erosion induced catchment scale organic carbon redistribution, we studied the subcatchments of 8 check-dams distributed along the catchment main channel in detail. We determined 137Cs, physicochemical characteristics and organic carbon pools of soils and sediments deposited behind each check-dam, performed spatial analysis of properties of the catchment and buffer areas around check-dams, and carried out geomorphological analysis of the slope-channel connections. Soils showed very low Total Organic Carbon (TOC) values oscillating between 15.2 and 4.4 g Kg-1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC compared to the eroded (forest) soils (6.6±0.7 g Kg-1), and the redistribution of organic carbon through the catchment, especially of the Mineral Associated Organic Carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates (0.031±0.03 Mg ha-1 y-1) were comparable to others reported for subhumid Mediterranean catchments and to those modelled worldwide for pasture land. Those lateral fluxes were equivalent to 10.4 % of the TOC stock from the topsoil at the moment of the check-dam construction and

  12. The Influence of temporal sampling regime on the WFD classification of catchments within the Eden Demonstration Test Catchment Project

    NASA Astrophysics Data System (ADS)

    Jonczyk, Jennine; Haygarth, Phil; Quinn, Paul; Reaney, Sim

    2014-05-01

    A high temporal resolution data set from the Eden Demonstration Test Catchment (DTC) project is used to investigate the processes causing pollution and the influence of temporal sampling regime on the WFD classification of three catchments. This data highlights WFD standards may not be fit for purpose. The Eden DTC project is part of a UK government-funded project designed to provide robust evidence regarding how diffuse pollution can be cost-effectively controlled to improve and maintain water quality in rural river catchments. The impact of multiple water quality parameters on ecosystems and sustainable food production are being studied at the catchment scale. Three focus catchments approximately 10 km2 each, have been selected to represent the different farming practices and geophysical characteristics across the Eden catchment, Northern England. A field experimental programme has been designed to monitor the dynamics of agricultural diffuse pollution at multiple scales using state of the art sensors providing continuous real time data. The data set, which includes Total Phosphorus and Total Reactive Phosphorus, Nitrate, Ammonium, pH, Conductivity, Turbidity and Chlorophyll a reveals the frequency and duration of nutrient concentration target exceedance which arises from the prevalence of storm events of increasing magnitude. This data set is sub-sampled at different time intervals to explore how different sampling regimes affects our understanding of nutrient dynamics and the ramification of the different regimes to WFD chemical status. This presentation seeks to identify an optimum temporal resolution of data for effective catchment management and to question the usefulness of the WFD status metric for determining health of a system. Criteria based on high frequency short duration events needs to be accounted for.

  13. Integrating observations and models to help understanding how flooding impacts upon catchments as a basis for decision making.

    NASA Astrophysics Data System (ADS)

    Owen, Gareth; Quinn, Paul; O'Donnell, Greg

    2014-05-01

    This paper explains how flood management projects might be better informed in the future by using more observations and a novel impact modelling tool in a simple transparent framework. The understanding of how local scale impacts propagate downstream to impact on the downstream hydrograph is difficult to determine using traditional rainfall runoff and hydraulic routing methods. The traditional approach to modelling essentially comprises selecting a fixed model structure and then calibrating to an observational hydrograph, which make those model predictions highly uncertain. Here, a novel approach is used in which the structure of the runoff generation is not specified a priori and incorporates expert knowledge. Rather than using externally for calibration, the observed outlet hydrographs are used directly within the model. Essentially the approach involves the disaggregation of the outlet hydrograph by making assumptions about the spatial distribution of runoff generated. The channel network is parameterised through a comparison of the timing of observed hydrographs at a number of nested locations within the catchment. The user is then encouraged to use their expert knowledge to define how runoff is generated locally and what the likely impact of any local mitigation is. Therefore the user can specify any hydrological model or flow estimation method that captures their expertise. Equally, the user is encouraged to install as many instruments as they can afford to cover the catchment network. A Decision Support Matrix (DSM) is used to encapsulate knowledge of the runoff dynamics gained from simulation in a simple visual way and hence to convey the likely impacts that arise from a given flood management scenario. This tool has been designed primarily to inform and educate landowners, catchment managers and decision makers. The DSM outlines scenarios that are likely to increase or decrease runoff rates and allows the user to contemplate the implications and

  14. 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.

  15. Minimizing the effects of filtering on catchment scale GRACE solutions

    NASA Astrophysics Data System (ADS)

    Dutt Vishwakarma, Bramha; Devaraju, Balaji; Sneeuw, Nico

    2016-08-01

    The Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided time variable gravity information since its launch in 2002. Due to short-wavelength noise, the total water storage variations over a catchment observed from GRACE are usable only after filtering. Filtering smooths both the signal and the noise, inevitably changing the nature of the estimated total water storage change. The filtered estimates suffer from attenuation and leakage, which changes the signal characteristics. Several studies have mainly focused on correcting the changed amplitude with the aid of hydrological models. In this study, it is demonstrated that in addition to the amplitude loss, also significant phase change in the time series of total water storage over a region can occur. The phase change due to leakage from nearby catchments can be around 20° to 30° for catchments with moderate size, which makes it difficult to retrieve signal by only scaling. We propose a strategy to approach the true time series with improved phase and amplitude. The strategy is independent of any hydrological model. It is first demonstrated in a closed-loop environment over 32 catchments, where we show that the performance of our method is consistent and better than other model-dependent approaches. Then we also discuss the limitations of our approach. Finally we apply our method to the GRACE level 2 products for 32 catchments.

  16. 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.

  17. Human disturbance of the Waitomo catchment, New Zealand.

    PubMed

    van Beynen, Philip E; Bialkowska-Jelinska, Elzbieta

    2012-10-15

    The karst disturbance index (KDI) consists of 31 environmental indicators categorized within the five broad categories of geomorphology, hydrology, atmosphere, biota, and culture. This article discusses the application of the KDI to the rural karst region of Waitomo, New Zealand. Previous applications of the KDI measured disturbance to urban areas as delineated by geo-political boundaries while this study used a physical boundary of a small karst catchment. Such an approach ensures greater environmental specificity of measured disturbance levels compared to those determined according to arbitrary, politically defined areas. The study included a comparison of a local resource manager and a visiting karst expert's determinations of disturbance levels for the catchment. Overall, the Waitomo catchment was found to be moderately disturbed. The only significant, direct disturbances were deforestation and erosion; however, these lead to the indirect disturbance of cave biota, water quality and accelerated sedimentation of the catchment's waterways. We have a high degree of confidence in the validity of these results due to the ability to assess all of the applicable indicators in the index, and the consistency of scoring by both individuals who applied the index. The benefit of applying the KDI at the catchment level is the greater accuracy measuring disturbance as opposed to applying the index within geo-political boundaries that incorporate both karst and non-karst terrains. With disturbance data for a highly specific area, the Waitomo resource managers have the improved ability to effectively identify, target, remediate, and manage human disturbance of the karst landscape.

  18. An Open-Source Approach for Catchment's Physiographic Characterization

    NASA Astrophysics Data System (ADS)

    Di Leo, M.; Di Stefano, M.

    2013-12-01

    A water catchment's hydrologic response is intimately linked to its morphological shape, which is a signature on the landscape of the particular climate conditions that generated the hydrographic basin over time. Furthermore, geomorphologic structures influence hydrologic regimes and land cover (vegetation). For these reasons, a basin's characterization is a fundamental element in hydrological studies. Physiographic descriptors have been extracted manually for long time, but currently Geographic Information System (GIS) tools ease such task by offering a powerful instrument for hydrologists to save time and improve accuracy of result. Here we present a program combining the flexibility of the Python programming language with the reliability of GRASS GIS, which automatically performing the catchment's physiographic characterization. GRASS (Geographic Resource Analysis Support System) is a Free and Open Source GIS, that today can look back on 30 years of successful development in geospatial data management and analysis, image processing, graphics and maps production, spatial modeling and visualization. The recent development of new hydrologic tools, coupled with the tremendous boost in the existing flow routing algorithms, reduced the computational time and made GRASS a complete toolset for hydrological analysis even for large datasets. The tool presented here is a module called r.basin, based on GRASS' traditional nomenclature, where the "r" stands for "raster", and it is available for GRASS version 6.x and more recently for GRASS 7. As input it uses a Digital Elevation Model and the coordinates of the outlet, and, powered by the recently developed r.stream.* hydrological tools, it performs the flow calculation, delimits the basin's boundaries and extracts the drainage network, returning the flow direction and accumulation, the distance to outlet and the hill slopes length maps. Based on those maps, it calculates hydrologically meaningful shape factors and

  19. Pesticide and metabolite fate, release and transport modelling at catchment scale

    NASA Astrophysics Data System (ADS)

    Gaßmann, Matthias; Olsson, Oliver; Bauer, Melanie

    2010-05-01

    Pesticides are of great concern in hydrological catchments all over the world. On the one hand they are necessary to guarantee stable agricultural production for an increasing population. On the other hand they endanger life of aquatic animals and freshwater resources. However, not only pesticides but also their degradation products, the metabolites, are toxic to the environment, in some cases even more than the parent material. Thus, it is necessary to optimize pesticide application and management of agricultural land (e.g. grass strips, erosion prevention) with respect and according to their behaviour and degradation in hydrological catchments. Modelling provides a sound tool for assessing the impacts of pesticide management changes on pesticide behaviour at the field and in consecutively surface waters. Most of the various models available in literature do not consider metabolism. This study introduces an applicable integrated model assessing the fate and release of a pesticide and one metabolite at the field and in surface waters of a hydrological catchment. For the development of the field release model, the single-equation pesticide release formula by the OECD (2000) was used, which combines sorption and degradation in one equation. The part of the equation calculating the degradation forms the input of a second OECD equation representing the metabolite with its own parameters. A fraction can be specified describing how much of the degradation product is transferred to the specific metabolite. The river network is simulated with a further development of the MOHID River Network model (MRN). The integration of a pesticide type and a metabolite, with their degradation and volatilization processes are the main improvements of the hydrodynamic channel model. Following, the combined model was set up to the Israeli part of the Upper Jordan River basin, especially the Hula valley. According to the local hydrological conditions, a linear storage with a threshold was

  20. Coupling soil moisture and precipitation observations for predicting hourly runoff at small catchment scale

    NASA Astrophysics Data System (ADS)

    Tayfur, Gokmen; Zucco, Graziano; Brocca, Luca; Moramarco, Tommaso

    2014-03-01

    The importance of soil moisture is recognized in rainfall-runoff processes. This study quantitatively investigates the use of soil moisture measured at 10, 20, and 40 cm soil depths along with rainfall in predicting runoff. For this purpose, two small sub-catchments of Tiber River Basin, in Italy, were instrumented during periods of October 2002-March 2003 and January-April 2004. Colorso Basin is about 13 km2 and Niccone basin 137 km2. Rainfall plus soil moisture at 10, 20, and 40 cm formed the input vector while the discharge was the target output in the model of generalized regression neural network (GRNN). The model for each basin was calibrated and tested using October 2002-March 2003 data. The calibrated and tested GRNN was then employed to predict runoff for each basin for the period of January-April 2004. The model performance was found to be satisfactory with determination coefficient, R2, equal to 0.87 and Nash-Sutcliffe efficiency, NS, equal to 0.86 in the validation phase for both catchments. The investigation of effects of soil moisture on runoff prediction revealed that the addition of soil moisture data, along with rainfall, tremendously improves the performance of the model. The sensitivity analysis indicated that the use of soil moisture data at different depths allows to preserve the memory of the system thus having a similar effect of employing the past values of rainfall, but with improved GRNN performance.

  1. A simple hydrologic model for rapid prediction of runoff from ungauged coastal catchments

    NASA Astrophysics Data System (ADS)

    Wan, Yongshan; Konyha, Kenneth

    2015-09-01

    We developed a lumped conceptual rainfall-runoff model for rapid prediction of runoff generated in the unique hydrological setting with flat terrain, sandy soils, high groundwater table, and a dense drainage canal network in south Florida. The model is conceptualized as rainfall and evapotranspiration filling and emptying the root zone and excess rainfall recharging three storage zones. Outflows from these storage zones, routed with parallel arrangement of three linear reservoirs, represent different flow components of catchment runoff, i.e., slow drainage (shallow subsurface flow), medium drainage (interflow and saturation excess overland flow), and fast drainage (direct runoff from impervious urban areas or from water table management in agricultural land). The model is parsimonious with eight model parameters along with two optional water management parameters. A regionalization study was conducted through model parameterization to achieve target hydrological behavior of typical land uses, which are the most significant basin descriptor affecting catchment hydrology in south Florida. Cross validation with 16 gauged basins dominated by urban, agricultural, and natural lands, respectively, indicated that the model provides an effective tool for rapid prediction of runoff in ungauged basins using the regionalized model parameters. A case study is presented, involving application of the model to support real-time adaptive management to hydrological operations for protection of estuarine ecosystems.

  2. The influence of a lake-wetland complex on catchment nutrient flux and speciation

    NASA Astrophysics Data System (ADS)

    Covino, T. P.; McGlynn, B. L.; Kalinin, A.

    2013-12-01

    Lakes and wetlands within stream networks can substantially alter the timing, magnitude, and form of nutrient export to downstream receiving bodies. These linked systems have the capacity to alter water chemistry and buffer downstream export of nutrients through combined physical, chemical, and biological processes. In many mountainous catchments wetlands are located at the inlet of lakes, thus forming lake-wetland complexes. In this study we investigated the influence an in network lake-wetland complex exerted on the timing, magnitude, and form of carbon and nitrogen export from the Bull Trout Lake Watershed (11.4 km2) located in the Sawtooth Mountains of central Idaho, USA. We: 1) injected conservative tracer to determine lake residence times; and 2) sampled the lake inflow, outflow, and six sites across the lake on hourly to bi-weekly intervals over 5 months (May - September) to capture the spatial and temporal dynamics of injected tracers and catchment nutrient fluxes. Lake sampling sites were each sampled at six depths to capture all strata of the lake. Injected tracer had a median travel time of one week and a modal travel time of four days. Additionally, longer residence times were observed in deeper (>8 m) regions of the lake. We observed that nitrate (NO3-N) was the dominant form of dissolved inorganic nitrogen (DIN) at the lake inflow whereas ammonium (NH4-N) became the dominant component at the lake outflow. Specifically, NO3-N accounted for 62% of DIN at the inflow and NH4-N comprised 58% percent of DIN at the lake outflow 600 m downstream. Dissolved organic nitrogen (DON) comprised the majority of total dissolved nitrogen (TDN) at both the lake inflow and outflow, and within the lake accounting for 92% of the seasonal TDN flux. There was a positive net export of NH4-N, DON, TDN, and dissolved organic carbon (DOC) and a negative net flux of NO3-N from the inlet to the outlet of the lake-wetland complex. Additionally, we observed high concentrations of

  3. Exploration of a Dynamic Merging Scheme for Precipitation Estimation over a Small Urban Catchment

    NASA Astrophysics Data System (ADS)

    Al-Azerji, Sherien; Rico-Ramirez, Miguel, ,, Dr.; Han, Dawei, ,, Prof.

    2016-04-01

    The accuracy of quantitative precipitation estimation is of significant importance for urban areas due to the potentially damaging consequences that can result from pluvial flooding. Improved accuracy could be accomplished by merging rain gauge measurements with weather radar data through different merging methods. Several factors may affect the accuracy of the merged data, and the gauge density used for merging is one of the most important. However, if there are no gauges inside the research area, then a gauge network outside the research area can be used for the merging. Generally speaking, the denser the rain gauge network is, the better the merging results that can be achieved. However, in practice, the rain gauge network around the research area is fixed, and the research question is about the optimal merging area. The hypothesis is that if the merging area is too small, there are fewer gauges for merging and thus the result would be poor. If the merging area is too large, gauges far away from the research area can be included in merging. However, due to their large distances, those gauges far away from the research area provide little relevant information to the study and may even introduce noise in merging. Therefore, an optimal merging area that produces the best merged rainfall estimation in the research area could exist. To test this hypothesis, the distance from the centre of the research area and the number of merging gauges around the research area were gradually increased and merging with a new domain of radar data was then performed. The performance of the new merging scheme was compared with a gridded interpolated rainfall from four experimental rain gauges installed inside the research area for validation. The result of this analysis shows that there is indeed an optimum distance from the centre of research area and consequently an optimum number of rain gauges that produce the best merged rainfall data inside the research area. This study is of

  4. Effect of urbanisation on the water balance of a catchment with shallow groundwater

    NASA Astrophysics Data System (ADS)

    Barron, O. V.; Barr, A. D.; Donn, M. J.

    2013-04-01

    SummaryThe impact of urbanisation on the water balance of a catchment dominated by surface water and groundwater interactions was investigated by using a process-based coupled surface water and groundwater model called MODHMS. The modelling estimated the likely changes in river discharge as a result of the land use change in the Southern River catchment in Western Australia. The catchment has both permeable soils and a shallow watertable. There was a significant increase in total annual discharge from the urbanised area where the runoff coefficient rose from 0.01 to more than 0.40. However in contrast with urban areas elsewhere these changes were mainly due to a shift in the subsurface water balance, including both groundwater and the unsaturated zone due to specifics of local hydrogeological conditions and adopted practice of storm runoff management. Due to the highly permeable soils, it is also common practice in the local building industry to direct runoff from roofs and roads into the soil and thereby the unconfined aquifer. Urbanisation results in particularly large changes in evapotranspiration from the soil profile and shallow watertable. The total subsurface evaporative flux reduced from 90% of infiltration (or 63-68% rainfall) to less than 29% (or 20% of rainfall) after urbanisation. Up to 83% (or 443 mm) of the pre-development evapotranspiration flux was from the shallow watertable. The requirement to control groundwater levels with drains in the shallow unconfined aquifer as well as the introduction of impervious surfaces caused a significant reduction of this component of evapotranspiration to less than 154 mm. These combined with an increase in infiltration rates, due to the direct infiltration of roof and road runoff, lead to higher groundwater recharge rates and subsequently groundwater discharge to the urban drainage network. The magnitude of urbanisation on catchment fluxes is most strongly influenced by urban density and the rate of local

  5. Influence of high resolution rainfall data on the hydrological response of urban flat catchments

    NASA Astrophysics Data System (ADS)

    Cristiano, Elena; ten Veldhuis, Marie-claire; van de Giesen, Nick

    2016-04-01

    In the last decades, cities have become more and more urbanized and population density in urban areas is increased. At the same time, due to the climate changes, rainfall events present higher intensity and shorter duration than in the past. The increase of imperviousness degree, due to urbanization, combined with short and intense rainfall events, determinates a fast hydrological response of the urban catchment and in some cases it can lead to flooding. Urban runoff processes are sensitive to rainfall spatial and temporal variability and, for this reason, high resolution rainfall data are required as input for the hydrological model. A better knowledge of the hydrological response of system can help to prevent damages caused by flooding. This study aims to evaluate the sensitivity of urban hydrological response to spatial and temporal rainfall variability in urban areas, focusing especially on understanding the hydrological behaviour in lowland areas. In flat systems, during intense rainfall events, the flow in the sewer network can be pressurized and it can change direction, depending on the setting of pumping stations and CSOs (combined sewer overflow). In many cases these systems are also looped and it means that the water can follow different paths, depending on the pipe filling process. For these reasons, hydrological response of flat and looped catchments is particularly complex and it can be difficult characterize and predict it. A new dual polarimetric X-band weather radar, able to measure rainfall with temporal resolution of 1 min and spatial resolution of 100mX100m, was recently installed in the city of Rotterdam (NL). With this instrument, high resolution rainfall data were measured and used, in this work, as input for the hydrodynamic model. High detailed, semi-distributed hydrodynamic models of some districts of Rotterdam were used to investigate the hydrological response of flat catchments to high resolution rainfall data. In particular, the

  6. Soil water content and green water estimations in a small farmed semiarid catchment

    NASA Astrophysics Data System (ADS)

    Mekki, I.; Voltz, M.; Ben Mechlia, N.; Albergel, J.

    2012-04-01

    The main objective of this work is to analyze the spatial and temporal variation of soil water content and green water production over a farmed water harvesting catchment, located in north-eastern Tunisia. The area has a typical Mediterranean climate with a hot dry summer and a cool season, extending from October to April, where rainfall normally meets the water requirements of the usually grown cereals and legumes (500mm). The catchment has an area of 2.6 km2 and comprises at its outlet a dam, which retains the runoff water in a reservoir. Soil water balance measurements were carried out, about weekly, over two successive cropping cycles (2000-2002) on a network of eleven plots of 2 m2 each, representing the main land use and soil types. Soil water store investigations targeted the different individual plots as well as the entire catchment. We used a simple water balance model, where the root zone is considered as a single reservoir, to simulate soil water content variations. Results show a fairly good agreement between the calculated and measured water store for all experimental sites. The model reproduces accurately the soil water content during the beginning of the rainy season but underestimates it during the season when heavy rains occur. On heavy soils, simulated soil moisture was lower than measured values, giving differences as high as 25% between simulated water store amounts and the neutron probe measurement values. For the cereals/legume/pasture based cropping systems, most of rainfall water is stored in the soil and returns to the atmosphere by evapotranspiration. The 0-0.3 m soil layer is most active for water uptake by crops and intermittent replenishment by rainfall during the growing period; whereas drying involves the entire soil profile over the summer season (May-Seeptmber). The available water holding capacity of the soil turned out to be about seven times the storage capacity of the reservoir, showing the order of magnitude of rainfall

  7. Relationships between precipitation, seismic noise and river chemistry in a well-instrumented mountain catchment

    NASA Astrophysics Data System (ADS)

    Emberson, Robert

    2013-04-01

    Recent work (e.g. Burtin et al. 2008, Hsu et al. 2011) has shown continuous recording of seismic noise with a close-knit network of seismometers can be used to locate geomorphic events within a catchment, both spatially and temporally. Although this has significance for modelling of physical erosion within a landscape, the link between these events and chemical weathering is not as clearly defined. The role that precipitation plays in triggering these events as well as its influence on seismic noise is also in need of clarification, particularly as many of the events would not be visible from aerial mapping alone (Burtin et al., in review). This study uses a series of datasets collected during the summer of 2010 in a well instrumented, mountainous catchment in Taiwan to better elucidate these connections. High frequency recording of rainfall, continuous seismic noise recording and daily records of river chemistry and suspended sediment load are used to look at the short term controls on geomorphic activity and the resulting chemical weathering. A close tie is found between rainfall intensity and timing of seismically located geomorphic events, likely indicating reactivation of existing landslide scars. An exponential increase in the efficiency of activation is seen with increasing rainfall, even during a relatively quiescent typhoon season. This corresponds to the increase in seismic noise with increasing rainfall following a power-law relationship. In terms of the chemical weathering data, 72 hour prior average seismic noise is quite well correlated (p=0.703) with river ratios of Ca/Sr, giving an independent constraint on the rate of carbonate reprecipitation. Measurement of river water chemistry in two locations within the catchment reveals significant local disparities in major cation concentrations, likely caused by lithological differences and variable hydrothermal input. Hydrograph deconvolution using stable isotopes will allow for separation of these

  8. Testing fine sediment connectivity hypotheses using fallout radionuclide tracers in a small catchment with badlands. Vallcebre Research Catchments (NE Spain)

    NASA Astrophysics Data System (ADS)

    Gallart, Francesc; Latron, Jérôme; Vuolo, Diego; Martínez-Carreras, Núria; Pérez-Gallego, Nuria; Ferrer, Laura; Estrany, Joan

    2016-04-01

    In the Vallcebre Research Catchments (NE Spain), results obtained during over 20 years showed that badlands are the primary sources of sediments to the drainage network. Parent lutitic rocks are weathered during winter producing regoliths, which are eroded from badland surfaces mainly during summer intense rainstorms. Even if the produced sediments are mainly fine, due to the ephemeral nature of summer runoff events most of them are deposited on the stream beds, where they may remain during some time (months to years). Within the MEDhyCON project, a fallout radionuclides (FRNs) tracing experiment (i.e., excess lead 210 (Pbx-210) and beryllium 7 (Be-7)) is being carried out in order to investigate sediment connectivity. A simplified Pbx-210 balance model on badland surfaces suggested a seasonal sawtooth-like activity pattern: FRN being accumulated in regoliths from October to June and depleted in summer. Early summer erosion events would produce the sediments with the highest activity whereas late summer events would produce sediments with the lowest activity coming from the deeper regolith horizons. These findings lead us to launch two sediment transfer connectivity hypotheses analysing respectively the temporal and spatial variability of the Pb-210 activities within the fine sediments at the small catchment scale: (1) The temporal variability of suspended sediment activities at the gauging stations is a measure of sediment transfer immediacy, ergo connectivity. Hence, a high variability in suspended sediment activities, mimicking regolith activity temporal pattern would indicate high connectivity, whereas a low variability, meaning that sediments are mostly pooled in a large and slowly moving stock, would indicate low connectivity. (2) In a drainage system where fine sediments temporarily remain on the dry stream bed, the ratio between fine sediment activities at the sources and fine in-stream sediment activities downstream is a measure of sediment connectivity

  9. The anthropic catchment-ecosystem concept: an Irish example

    SciTech Connect

    Phillips-Howard, K.D.

    1985-06-01

    The catchment-ecosystem concept is adapted to investigate the nutrient-budget of the highly-modified Colebrooke drainage basin in Northern Ireland. Anthropogenic inputs, mainly manures and fertilizers, account for 86% of the nitrogen and 96% of the phosphorus added to the catchment. These inputs greatly exceed the streamflow outputs, thereby indicating that the flow of nutrients is dominated by agriculture. This is explained by the transformation of traditional mixed farming into more intensive livestock production and is linked to policies encouraging increased agricultural production, amalgamation of farms, afforestation, rural depopulation, and urbanization. Substantial increases in the N and P output of the catchment and further eutrophication of the recipient lake, Lough Erne, are predicted without the implementation of policies to reduce agricultural nutrient losses.

  10. Understanding fine sediment and phosphorous delivery in upland catchments

    NASA Astrophysics Data System (ADS)

    Perks, M. T.; Reaney, S. M.

    2013-12-01

    The uplands of UK are heavily impacted by land management including; farming and forestry operations, moorland burning, peat extraction, metal mining, artificial drainage and channelisation. It has been demonstrated that such land management activity may modify hillslope processes, resulting in enhanced runoff generation and changing the spatial distribution and magnitude of erosion. Resultantly, few upland river systems of the UK are operating in a natural state, with land management activity often resulting in increased fluxes of suspended sediment (< 2 mm) and associated pollutants (such as phosphorous). Most recent Environment Agency (EA) data reveals that 60% of monitored water bodies within upland areas of the UK are currently at risk of failing the Water Framework Directive (WFD) due to poor ecological status. In order to prevent the continual degradation of many upland catchments, riverine systems and their diverse ecosystems, a range of measures to control diffuse pollution will need to be implemented. Future mitigation options and measures in the UK may be tested and targeted through the EA's catchment pilot scheme; DEFRA's Demonstration Test Catchment (DTC) programmes and through the catchment restoration fund. However, restoring the physical and biological processes of past conditions in inherently sensitive upland environments is extremely challenging requiring the development of a solid evidence base to determine the effectiveness of resource allocation and to enable reliable and transparent decisions to be made about future catchment operations. Such evidence is rarely collected, with post-implementation assessments often neglected. This paper presents research conducted in the Morland sub-catchment of the River Eden within Cumbria; UK. 80% of this headwater catchment is in upland areas and is dominated by improved grassland and rough grazing. The catchment is heavily instrumented with a range of hydro-meteorological equipment. A high-tech monitoring

  11. Contribution of rainfall, snow and ice melt to the hydrological regime of the Arve upper catchment and to severe flood events

    NASA Astrophysics Data System (ADS)

    Lecourt, Grégoire; Revuelto, Jesús; Morin, Samuel; Zin, Isabella; Lafaysse, Matthieu; Condom, Thomas; Six, Delphine; Vionnet, Vincent; Charrois, Luc; Dumont, Marie; Gottardi, Frédéric; Laarman, Olivier; Coulaud, Catherine; Esteves, Michel; Lebel, Thierry; Vincent, Christian

    2016-04-01

    In Alpine catchments, the hydrological response to meteorological events is highly influenced by the precipitation phase (liquid or solid) and by snow and ice melt. It is thus necessary to simulate accurately the snowpack evolution and its spatial distribution to perform relevant hydrological simulations. This work is focused on the upper Arve Valley (Western Alps). This 205 km2 catchment has large glaciated areas (roughly 32% of the study area) and covers a large range of elevations (1000-4500 m a.s.l.). Snow presence is significant year-round. The area is also characterized by steep terrain and strong vegetation heterogeneity. Modelling hydrological processes in such a complex catchment is therefore challenging. The detailed ISBA land surface model (including the Crocus snowpack scheme) has been applied to the study area using a topography based discretization (classifying terrain by aspect, elevation, slope and presence of glacier). The meteorological forcing used to run the simulations is the reanalysis issued from the SAFRAN model which assimilates meteorological observations from the Meteo-France networks. Conceptual reservoirs with calibrated values of emptying parameters are used to represent the underground water storage. This approach has been tested to simulate the discharge on the Arve catchment and three sub-catchments over 1990-2015. The simulations were evaluated with respect to observed water discharges for several headwaters with varying glaciated areas. They allow to quantify the relative contribution of rainfall, snow and ice melt to the hydrological regime of the basin. Additionally, we present a detailed analysis of several particular flood events. For these events, the ability of the model to correctly represent the catchment behaviour is investigated, looking particularly to the relevance of the simulated snowpack. Particularly, its spatial distribution is evaluated using MODIS snow cover maps, punctual snowpack observations and summer

  12. Extrapolating soil redistribution rates estimated from 137Cs to catchment scale in a complex agroforestry landscape using GIS

    NASA Astrophysics Data System (ADS)

    Gaspar, Leticia; López-Vicente, Manuel; Palazón, Leticia; Quijano, Laura; Navas, Ana

    2015-04-01

    The use of fallout radionuclides, particularly 137Cs, in soil erosion investigations has been successfully used over a range of different landscapes. This technique provides mean annual values of spatially distributed soil erosion and deposition rates for the last 40-50 years. However, upscaling the data provided by fallout radionuclides to catchment level is required to understand soil redistribution processes, to support catchment management strategies, and to assess the main soil erosion factors like vegetation cover or topography. In recent years, extrapolating field scale soil erosion rates estimated from 137Cs data to catchment scale has been addressed using geostatistical interpolation and Geographical Information Systems (GIS). This study aims to assess soil redistribution in an agroforestry catchment characterized by abrupt topography and an intricate mosaic of land uses using 137Cs data and GIS. A new methodological approach using GIS is presented as an alternative of interpolation tools to extrapolating soil redistribution rates in complex landscapes. This approach divides the catchment into Homogeneous Physiographic Units (HPUs) based on unique land use, hydrological network and slope value. A total of 54 HPUs presenting specific land use, strahler order and slope combinations, were identified within the study area (2.5 km2) located in the north of Spain. Using 58 soil erosion and deposition rates estimated from 137Cs data, we were able to characterize the predominant redistribution processes in 16 HPUs, which represent the 78% of the study area surface. Erosion processes predominated in 6 HPUs (23%) which correspond with cultivated units in which slope and strahler order is moderate or high, and with scrubland units with high slope. Deposition was predominant in 3 HPUs (6%), mainly in riparian areas, and to a lesser extent in forest and scrubland units with low slope and low and moderate strahler order. Redistribution processes, both erosion and

  13. From hydro-geomorphological mapping to sediment transfer evaluation in the Upper Guil Catchment (Queyras, French Alps)

    NASA Astrophysics Data System (ADS)

    Lissak, Candide; Fort, Monique; Arnaud-Fassetta, Gilles; Mathieu, Alexandre; Malet, Jean-Philippe; Carlier, Benoit; Betard, François; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charney, Bérengère; Bletterie, Xavier

    2014-05-01

    proposed methodology is based on data directly derived from GIS analysis using interpretation of aerial photographs, regional scale Digital Elevation Model (DEM), high-resolution DEM derived from airborne-based LiDAR, and field survey. The data thus obtained can be used in the final geomorphological map. Future investigations will quantify the contribution of each sub-catchment in the global sediment budget of the Guil catchment. For a better assessment of sediment fluxes and sediment delivery into the main channel network, tracers (pit-tags) and diachronic Terrestrial Laser Scanning will be performed in selected sub-catchments in order to measure erosion rates and contribution to the sediment yield in the valley bottoms during the floods, avalanches and rainfall seasonal events.

  14. An event-based approach to understanding the hydrological impacts of different land uses in semi-arid catchments

    NASA Astrophysics Data System (ADS)

    Wang, Shengping; Zhang, Zhiqiang; McVicar, Tim R.; Zhang, Jianjun; Zhu, Jinzhao; Guo, Junting

    2012-01-01

    SummaryIn semi-arid catchments around the world re-vegetation is often implemented to reduce quick surface runoff, combat severe soil erosion, restore degraded ecosystem functionality, and, ultimately, improve ecosystem productivity. However, to date, in these water stressed regions, the event-based hydrological impact of different land uses induced by re-vegetation activities is not fully understood at the watershed scale. Traditional hillslope plot experiments and paired watershed experiments have proved difficult to up-scale to a watershed level. In 2006 and 2007, we used broad-crested weirs to measure event streamflow from six catchments within the Caijiachuan watershed (area = 40.1 km 2), located in the Loess Plateau, a semi-arid region in China. The six catchments have different land use compositions with functional combinations of crop, grassland, shrubland, secondary forest, and plantations. Over the same period, event rainfall was measured by a network of rainfall gauges deployed over the study site. We examined the difference in hydrological properties between the catchments using the non-parametric Firedman test, and differentiated the role of each land use in governing watershed hydrology using a numerical analysis technique. Our results showed important differences between the six catchments with respect to event runoff coefficients, normalized peak flow, and event duration. Each land use played a different role in catchment hydrology, as shown by the different mean runoff coefficients ( rc) and mean representative surface flow velocities ( V). Compared to secondary forest ( rc = 0.017 and V = 0.07 m s -1), plantations ( rc = 0.001 and V = 0.18 m s -1) provide a greater potential for increasing shearing force and had a larger impact on runoff reduction. Although shrubland ( rc = 0.096 and V = 0.20 m s -1) and grassland ( rc = 0.127 and V = 0.02 m s -1) have similar magnitude of mean runoff coefficients, grassland seems more capable of trapping sediment

  15. 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, ...

  16. 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, ...

  17. Runoff Production in the Upper Rio Chagres Catchment, Panama

    NASA Astrophysics Data System (ADS)

    Niezialek, J. M.; Ogden, F. L.

    2003-12-01

    Runoff production in watersheds in the seasonal tropics is governed by a number of factors. The mountainous 414 sq. km upper Rio Chagres watershed offers a unique opportunity to better understand the runoff production mechanisms in seasonal tropical catchments through data analysis and modeling. The upper Rio Chagres catchment provides the majority of inflows to the Panama Canal, has been monitored for over 60 years as part of canal operations. Discharge data are available at both the catchment outlet (Chico gaging station) and an internal catchment location (Rio Piedras gaging station). There are also seven tipping bucket recording rain gages in and around the catchment. Analysis of runoff data reveals anomalously-high runoff production efficiencies early in the wet season. Furthermore, the existence of two quasi-stable base flow regimes during the wet season imply critical threshold storages. Initial field studies have shown that the soils are water repellent during the dry season. Runoff data from the 80 sq. km Rio Piedras subcatchment reveal ephemeral flows throughout the wet season, indicating significant heterogeneity in runoff production and deep groundwater circulation. Preliminary hydrologic modeling is performed with the Sacramento Soil Moisture Accounting Model (SAC-SMA), calibrated using data from 1988 and verified using data from 1989. Further modeling on the flood of 28-31 December, 2000 is also performed. Modeling using the distributed parameter GSSHA model combined with the Sacramento groundwater module allows simulation of distributed runoff. However, the role of interception by the triple-layer tropical canopy and the magnitude of evapotranspiration are uncertain. New data collection is proposed in the Rio Chagres catchment to help quantify interception and evapotranspiration. This instrumentation will include measurements of rainfall above the canopy, cloud stripping, stemflow, throughfall, soil moisture, groundwater, interflow

  18. Contribution of alluvial groundwater to the outflow of mountainous catchments

    NASA Astrophysics Data System (ADS)

    Käser, Daniel; Hunkeler, Daniel

    2016-02-01

    Alluvial aquifers in mountainous regions cover typically a limited area. Their contribution to catchment storage and outflow is rarely isolated; alluvial groundwater discharge under gauging stations is generally assumed negligible; and hydrological models tend to lump alluvial storage with other units. The role of alluvial aquifers remains therefore unclear: can they contribute significantly to outflow when they cover a few percent of catchment area? Should they be considered a dynamic storage unit or merely a transmission zone? We address these issues based on the continuous monitoring of groundwater discharge, river discharge (one year), and aquifer storage (6 months) in the 6 km2 alluvial system of a 194 km2 catchment. River and groundwater outflow were measured jointly through "coupled gauging stations." The contribution of alluvial groundwater to outflow was highest at the outlet of a subcatchment (52 km2), where subsurface discharge amounted to 15% of mean annual outflow, and 85% of outflow during the last week of a drought. In this period, alluvial-aquifer depletion supported 75% of the subcatchment outflow and 35% of catchment outflow—thus 3% of the entire catchment supported a third of the outflow. Storage fluctuations occurred predominantly in the aquifer's upstream part, where heads varied over 6 m. Not only does this section act as a significant water source, but storage recovers also rapidly at the onset of precipitation. Storage dynamics were best conceptualized along the valley axis, rather than across the more conventional riparian-channel transect. Overall the contribution of alluvial aquifers to catchment outflow deserves more attention.

  19. Runoff predictions in ungauged catchments in southeast Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Li, Fapeng; Zhang, Yongqiang; Xu, Zongxue; Liu, Changming; Zhou, Yanchun; Liu, Wenfeng

    2014-04-01

    The Tibetan Plateau (TP) plays a key role on both hydrology and climate for southern and eastern Asia. Improving runoff predictions in ungauged catchments in the TP is critical for surface water hydrology and water resources management in this region. However, a detailed runoff prediction study in this region has not been reported yet. To fill the gap, this study evaluates two regionalization approaches, spatial proximity and physical similarity, for predicting runoff using two rainfall-runoff models (SIMHYD and GR4J). These models are driven by meteorological inputs from eight large non-nested catchments (4000-50,000 km2) in the Yarlung Tsangpo River basin located in southeast TP. For each catchment, the two models are calibrated using data from the first two-thirds of the observation period and validated over the remaining period. The calibrated and validated Nash-Sutcliffe Efficiency of monthly runoff (NSE) varies from 0.73 to 0.93 for the SIMHYD model, and are similar to or slightly better than those obtained for the GR4J model. The incorporation of snowfall-snowmelt processes into the rainfall-runoff models does not noticeably improve the runoff predictions in the study area. The main reason is that monthly runoff is dominated by summer precipitation and snowfall in winter accounts for a small percentage (less than 14%). The results from both models show that the spatial proximity approach marginally outperforms the physical similarity approach and both approaches are better than random selection of a donor catchment. This is consistent with recent regionalization studies carried out in Europe and Australia. The study suggests that conceptual rainfall-runoff models are powerful and simple tools for monthly runoff predictions in large catchments in southeast TP, and incorporation of more catchments into regionalization can further improve prediction skills.

  20. Nutrient loads exported from managed catchments reveal emergent biogeochemical stationarity

    NASA Astrophysics Data System (ADS)

    Basu, Nandita B.; Destouni, Georgia; Jawitz, James W.; Thompson, Sally E.; Loukinova, Natalia V.; Darracq, Amélie; Zanardo, Stefano; Yaeger, Mary; Sivapalan, Murugesu; Rinaldo, Andrea; Rao, P. Suresh C.

    2010-12-01

    Complexity of heterogeneous catchments poses challenges in predicting biogeochemical responses to human alterations and stochastic hydro-climatic drivers. Human interferences and climate change may have contributed to the demise of hydrologic stationarity, but our synthesis of a large body of observational data suggests that anthropogenic impacts have also resulted in the emergence of effective biogeochemical stationarity in managed catchments. Long-term monitoring data from the Mississippi-Atchafalaya River Basin (MARB) and the Baltic Sea Drainage Basin (BSDB) reveal that inter-annual variations in loads (LT) for total-N (TN) and total-P (TP), exported from a catchment are dominantly controlled by discharge (QT) leading inevitably to temporal invariance of the annual, flow-weighted concentration, $\\overline{Cf = (LT/QT). Emergence of this consistent pattern across diverse managed catchments is attributed to the anthropogenic legacy of accumulated nutrient sources generating memory, similar to ubiquitously present sources for geogenic constituents that also exhibit a linear LT-QT relationship. These responses are characteristic of transport-limited systems. In contrast, in the absence of legacy sources in less-managed catchments, $\\overline{Cf values were highly variable and supply limited. We offer a theoretical explanation for the observed patterns at the event scale, and extend it to consider the stochastic nature of rainfall/flow patterns at annual scales. Our analysis suggests that: (1) expected inter-annual variations in LT can be robustly predicted given discharge variations arising from hydro-climatic or anthropogenic forcing, and (2) water-quality problems in receiving inland and coastal waters would persist until the accumulated storages of nutrients have been substantially depleted. The finding has notable implications on catchment management to mitigate adverse water-quality impacts, and on acceleration of global biogeochemical cycles.

  1. Rapid runoff via shallow throughflow and deeper preferential flow in a boreal catchment underlain by frozen silt (Alaska, USA)

    USGS Publications Warehouse

    Koch, Joshua C.; Ewing, Stephanie A.; Striegl, Robert G.; McKnight, Diane M.

    2013-01-01

    In high-latitude catchments where permafrost is present, runoff dynamics are complicated by seasonal active-layer thaw, which may cause a change in the dominant flowpaths as water increasingly contacts mineral soils of low hydraulic conductivity. A 2-year study, conducted in an upland catchment in Alaska (USA) underlain by frozen, well-sorted eolian silt, examined changes in infiltration and runoff with thaw. It was hypothesized that rapid runoff would be maintained by flow through shallow soils during the early summer and deeper preferential flow later in the summer. Seasonal changes in soil moisture, infiltration, and runoff magnitude, location, and chemistry suggest that transport is rapid, even when soils are thawed to their maximum extent. Between June and September, a shift occurred in the location of runoff, consistent with subsurface preferential flow in steep and wet areas. Uranium isotopes suggest that late summer runoff erodes permafrost, indicating that substantial rapid flow may occur along the frozen boundary. Together, throughflow and deep preferential flow may limit upland boreal catchment water and solute storage, and subsequently biogeochemical cycling on seasonal to annual timescales. Deep preferential flow may be important for stream incision, network drainage development, and the release of ancient carbon to ecosystems

  2. Constitution of a catchment virtual observatory for sharing flow and transport models outputs

    NASA Astrophysics Data System (ADS)

    Thomas, Zahra; Rousseau-Gueutin, Pauline; Kolbe, Tamara; Abbott, Benjamin W.; Marçais, Jean; Peiffer, Stefan; Frei, Sven; Bishop, Kevin; Pichelin, Pascal; Pinay, Gilles; de Dreuzy, Jean-Raynald

    2016-12-01

    Predicting hydrological catchment behavior based on measurable (and preferably widely available) catchment characteristics has been one of the main goals of hydrological modelling. Residence time distributions provide synoptic information about catchment functioning and can be useful metrics to predict their behaviors. Moreover, residence time distributions highlight a wide range of characteristic scales (spatial and temporal) and mixing processes. However, catchment-specific heterogeneity means that the link between residence time distributions and catchment characteristics is complex. Investigating this link for a wide range of catchments could reveal the role of topography, geology, land-use, climate and other factors in controlling catchment hydrology. Meaningful comparison is often challenging given the diversity of data and model structures and formats. To address this need, we are introducing a new virtual platform called Catchment virtual Observatory for Sharing flow and transport models outputs (COnSOrT). The goal of COnSOrT is to promote catchment intercomparison by sharing calibrated model outputs. Compiling commensurable results in COnSOrT will help evaluate model performance, quantify inter-catchment controls on hydrology, and identify research gaps and priorities in catchment science. Researchers interested in sharing or using calibrated model results are invited to participate in the virtual observatory. Participants may test post-processing methods on a wide range of catchment environments to evaluate the generality of their findings.

  3. THE HYDROLOGIC RESPONSE OF A SMALL CATCHMENT TO CLEAR-CUTTING

    EPA Science Inventory

    We simulated how a landscape disturbance (e.g., fire or clear-cutting) alters hillslope and catchment hydrologic processes. Specifically, we simulated how the pattern and magnitude of tree removal in a catchment increases downslope transport of water and alters catchment soil moi...

  4. Modelling Pesticide Leaching At Column, Field and Catchment Scales I. Analysis of Soil Variability At Field and Catchment Scales

    NASA Astrophysics Data System (ADS)

    Gärdenäs, A.; Jarvis, N.; Alavi, G.

    The spatial variability of soil characteristics was studied in a small agricultural catch- ment (Vemmenhög, 9 km2) at the field and catchment scales. This analysis serves as a basis for assumptions concerning upscaling approaches used to model pesticide leaching from the catchment with the MACRO model (Jarvis et al., this meeting). The work focused on the spatial variability of two key soil properties for pesticide fate in soil, organic carbon and clay content. The Vemmenhög catchment (9 km2) is formed in a glacial till deposit in southernmost Sweden. The landscape is undulating (30 - 65 m a.s.l.) and 95 % of the area is used for crop production (winter rape, winter wheat, sugar beet and spring barley). The climate is warm temperate. Soil samples for or- ganic C and texture were taken on a small regular grid at Näsby Farm, (144 m x 144 m, sampling distance: 6-24 m, 77 points) and on an irregular large grid covering the whole catchment (sampling distance: 333 m, 46 points). At the field scale, it could be shown that the organic C content was strongly related to landscape position and height (R2= 73 %, p < 0.001, n=50). The organic C content of hollows in the landscape is so high that they contribute little to the total loss of pesticides (Jarvis et al., this meeting). Clay content is also related to landscape position, being larger at the hilltop locations resulting in lower near-saturated hydraulic conductivity. Hence, macropore flow can be expected to be more pronounced (see also Roulier & Jarvis, this meeting). The variability in organic C was similar for the field and catchment grids, which made it possible to krige the organic C content of the whole catchment using data from both grids and an uneven lag distance.

  5. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    SciTech Connect

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  6. Analysis on radiocesium concentration in rivers that have catchment areas affected by the fallout from Fukushima Daiichi Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    Taniguchi, Keisuke; Yoshimura, Kazuya; Sakaguchi, Aya; Yamamoto, Masayoshi; Onda, Yuichi

    2014-05-01

    Due to Fukushima Daiichi Nuclear Power Plant accident, radioactive materials including Cs-134 and Cs-137 were widely distributed in surrounded area. The radiocesiums have been transported in river networks. This study showed the monitoring results of radiocesium concentration in river waters and suspended sediments in Abukuma river basin and smaller coastal river catchments. The monitoring started at 6 sites from June 2011. Subsequently, additional 24 monitoring sites were installed between October 2012 and January 2013. Flow and turbidity (for calculation of suspended sediment concentration) were measured at each site, while suspended sediments and river water were collected every one or half month to measure Cs-134 and Cs-137 activity concentrations by gamma spectrometry. Activity concentrations of Cs-134 and Cs- 137 on suspended sediments were generally decreasing at all sites. The decreasing rate changed lower at about one year later from the accident. Activity concentration in river waters also showed the same tendency although there are only few data within 1 year from the accident. Activity concentrations measured at the same day are proportional to the mean catchment inventory. Therefore, the activity concentration can be normalized by the mean catchment inventory. The normalized activity can be fitted to following double exponential function: [At] = 1.551 exp (-5.265t) + 0.069 exp (-0.266 t), where t [year] is the time from the accident. There is no time evolution of Kd between suspended sediments and river water. Instead, Kd was varied spatially. Although the reason of the spatial variation is not clear for now, geology of the catchment (i.e. mineral composition of suspended particles) seems to relate to the variation.

  7. Modeling Phosphorus Dynamics in Multi-branched River and Lake Systems in the Lake Simcoe Catchment, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Jin, L.; Whitehead, P. G.; Baulch, H. M.; Butterfield, D.; Crossman, J.; Dillon, P.; Oni, S. K.; Futter, M.; O'Connor, E.

    2011-12-01

    Nutrient enrichment has long been recognized as a major cause of impaired water quality. In southern Ontario, Canada, high rates of agricultural and urban nutrient loading, particularly phosphorus (P), have contributed to serious problems of surface water eutrophication and groundwater contamination. In Lake Simcoe, the second largest lake in southern Ontario, anthropogenic nutrients have contributed to increased algal growth, low hypolimnetic oxygen concentrations and impaired fish reproduction. Even though efforts in recent years have reduced P loads to the lake and led to improved water quality, the improvement is not yet sufficient and continuing efforts are required. An ambitious water quality management program has been initiated to reduce phosphorus loads by 40% to the lake by 2045. Increasing population growth within the catchment, superimposed on increased climate variability and future climate change may make this P load reduction even more challenging to achieve. The main P sources to Lake Simcoe are tributaries and atmospheric deposition. Because atmospheric inputs are difficult to control, a significant focus must be on reducing loading from the tributaries of Lake Simcoe. To improve the understanding of the phosphorus delivery, storage and transport within the Lake Simcoe catchment, a new version of integrated catchment phosphorus model (INCA-P) with the full-branched river network has been applied to the Black River, a tributary of Lake Simcoe. The model simulates the fluxes of P entering the lake and apportions P among different sources in the catchment. The model can be used independently to explore impacts of increased sewage loads due to population growth, land use change, climate change as well as to assess different management practices and remediation strategies. The multi-branched nature of the new version of the model enables concurrent modelling of all tributaries (>20), which will facilitate large-scale assessment of growth and climate

  8. Utilising conservative tracers and spatial surveys to identify controls on pathways and DOC exports in an Arctic catchment.

    NASA Astrophysics Data System (ADS)

    Lessels, J. S.; Tetzlaff, D.; Dinsmore, K. J.; Street, L. E.; Dean, J.; Washbourne, I. J.; Billett, M. F.; Baxter, R.; Subke, J. A.; Wookey, P. A.

    2014-12-01

    Dissolved organic carbon (DOC) is typically the predominant form of carbon exported from headwater streams, it therefore represents a major carbon export from Arctic catchments. The projected deepening of thaw depth in permafrost regions, due to an increase in air temperature, may have a significant effect on the amount of DOC exported from these systems. However, quantification of the impacts of climate driven changes on DOC export are still highly uncertain. Understanding the processes controlling DOC export is therefore crucial in predicting the potential impact of projected environmental changes. The controls of DOC production and transport are heavily influenced by soil and vegetation, which are highly variable across the landscape. To completely understand these systems information regarding spatial variability of plants, soils and thaw depths must be taken into account. In this study sub-weekly sampling of DOC was undertaken throughout 2014 in a headwater (<1 km2) catchment in the Northwest Territories, Canada. Spatial surveys of soil properties, active thaw depth and normalised difference vegetation index (NDVI) were collected and used in conjunction with conservative stable water isotopes tracers and major ions to understand sources, flow pathways and timing of DOC exports from the catchment. Stable isotope tracers act as fingerprints of water allowing sources and pathways to be assessed. Observations reveal changing DOC concentrations throughout the season as the active layer deepens and the connectivity of the soils to the stream network throughout the catchment increases. Linking the DOC data with the conservative tracer response improves the identification of carbon pathways and fluxes from the soils; preliminary analysis indicates DOC is being delivered via deeper more mineral soils later in the season. The results indicate that the active layer depth has a strong influence on the amount of DOC exported from the system, independent of the amount of

  9. 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

  10. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Level 3 Ecoregions

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the estimated area of level 3 ecological landscape regions (ecoregions), as defined by Omernik (1987), compiled for every catchment of NHDPlus for the conterminous United States. The source data set is Level III Ecoregions of the Continental United States (U.S. Environmental Protection Agency, 2003). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4

  11. Attributes for NHDplus Catchments (Version 1.1) for the Conterminous United States: Population Density, 2000

    USGS Publications Warehouse

    Wieczorek, Michael; LaMottem, Andrew E.

    2010-01-01

    This data set represents the average population density, in number of people per square kilometer multiplied by 10 for the year 2000, compiled for every catchment of NHDPlus for the conterminous United States. The source data set is the 2000 Population Density by Block Group for the Conterminous United States (Hitt, 2003). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5

  12. Attributes for NHDPlus Catchments (Version 1.1) in the Conterminous United States: Bedrock Geology

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the area of bedrock geology types in square meters compiled for every catchment of NHDPlus for the conterminous United States. The source data set is the "Geology of the Conterminous United States at 1:2,500,000 Scale--A Digital Representation of the 1974 P.B. King and H.M. Beikman Map" (Schuben and others, 1994). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus

  13. Attributes for NHDPlus Catchments (Version 1.1): Level 3 Nutrient Ecoregions, 2002

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the area of each level 3 nutrient ecoregion in square meters, compiled for every catchment of NHDPlus for the conterminous United States. The source data are from the 2002 version of the U.S. Environmental Protection Agency's (USEPA) Aggregations of Level III Ecoregions for National Nutrient Assessment & Management Strategy (USEPA, 2002). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins

  14. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Hydrologic Landscape Regions

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the area of Hydrologic Landscape Regions (HLR) compiled for every catchment of NHDPlus for the conterminous United States. The source data set is a 100-meter version of Hydrologic Landscape Regions of the United States (Wolock, 2003). HLR groups watersheds on the basis of similarities in land-surface form, geologic texture, and climate characteristics. The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris

  15. Attributes for NHDPlus catchments (Version 1.1) for the conterminous United States: STATSGO soil characteristics

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents estimated soil variables compiled for every catchment of NHDPlus for the conterminous United States. The variables included are cation exchange capacity, percent calcium carbonate, slope, water-table depth, soil thickness, hydrologic soil group, soil erodibility (k-factor), permeability, average water capacity, bulk density, percent organic material, percent clay, percent sand, and percent silt. The source data set is the State Soil ( STATSGO ) Geographic Database (Wolock, 1997). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee

  16. Attributes for NHDPlus catchments (version 1.1) for the conterminous United States: surficial geology

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the area of surficial geology types in square meters compiled for every catchment of NHDPlus for the conterminous United States. The source data set is the "Digital data set describing surficial geology in the conterminous US" (Clawges and Price, 1999). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5, 7 and 9. MRB4, covering the Missouri River

  17. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Physiographic Provinces

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This dataset represents the area of each physiographic province (Fenneman and Johnson, 1946) in square meters, compiled for every catchment of NHDPlus for the conterminous United States. The source data are from Fenneman and Johnson's Physiographic Provinces of the United States, which is based on 8 major divisions, 25 provinces, and 86 sections representing distinctive areas having common topography, rock type and structure, and geologic and geomorphic history (Fenneman and Johnson, 1946). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins

  18. Attributes for NHDPlus Catchments (Version 1.1): Basin Characteristics, 2002

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents basin characteristics, compiled for every catchment in NHDPlus for the conterminous United States. These characteristics are basin shape index, stream density, sinuosity, mean elevation, mean slope, and number of road-stream crossings. The source data sets are the U.S. Environmental Protection Agency's NHDPlus and the U.S. Census Bureau's TIGER/Line Files. The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris

  19. Hydrogeophysical characterization and data integration for the Sardon catchment hard rock aquifer (Spain)

    NASA Astrophysics Data System (ADS)

    Francés, Alain Pascal; Mohammed, Abubeker Ali; Roy, Jean; Mahmoudzadeh Ardekani, Mohammad Reza; Lambot, Sébastien; Lubczynski, Maciek

    2010-05-01

    Unaltered hard rocks are hydrogeologically characterized by low primary porosity and permeability. Productive aquifers can however be supported by fractured and/or weathered hard rocks. In this type of composite aquifers, the upper weathered layers have typically a storage function while the underlying fissured layers have a transmissive function. Such aquifer sequence is usually highly heterogeneous because the weathered and fractured zones are controlled by various factors such as mineralogy and texture of lithologies, regional and local tectonics, paleoclimate and interaction between these factors. In the proposed study we attempt to develop an efficient and accurate method to provide the hydrological characterization of a small hard rock (granite) aquifer within Sardon catchment (~80km2), located in the Iberian Meseta (west of Salamanca, Spain). The proposed method is based on the integration of five techniques : i) field mapping; ii) remote sensing imagery analysis (RS); iii) geographical information system (GIS); iv) hydrogeophysics; v) numerical flow modeling. The geological mapping including characterization of fractures was processed in GIS through the combination of conventional field survey and analysis of aerial photographs and space borne imagery. The hydrogeophysics complemented the previous work by: i) sub-surface characterization of weathered layers using vertical electrical soundings (VES) at 61 locations, an electromagnetic (EM) transect perpendicular to the main valley (~3 km length) and electrical resistivity tomography (ERT) at 13 locations; ii) ground penetrating radar (GPR) to derive the depth of the groundwater table to complement the information of the piezometric monitoring network (35 transects with a total length of ~23 km) in order to provide additional constrain of the numerical flow model; iii) magnetic resonance sounding (MRS) to derive the depth-wise subsurface water content and aquifer transmissivity at 15 locations. The collected

  20. Managed Care in the Military: The Catchment Area Management Demonstrations

    DTIC Science & Technology

    1991-09-01

    Sill, where routine optometry examinations--which might otherwise be unavailable to retirees and their dependents--are made available to all...closest hospital. c. Includes other Army catchment areas in the continental United States, Alaska, Hawaii, and Panama that are under the authority of

  1. Identifying spatial variations in glacial catchment erosion with detrital thermochronology

    NASA Astrophysics Data System (ADS)

    Ehlers, Todd A.; Szameitat, Annika; Enkelmann, Eva; Yanites, Brian J.; Woodsworth, Glenn J.

    2015-06-01

    Understanding the spatial distribution of glacial catchment erosion during glaciation has previously proven difficult due to limited access to the glacier bed. Recent advances in detrital thermochronology provide a new technique to quantify the source elevation of sediment. This approach utilizes the tendency of thermochronometer cooling ages to increase with elevation and provides a sediment tracer for the elevation of erosion. We apply this technique to the Tiedeman Glacier in the heavily glaciated Mount Waddington region, British Columbia. A total of 106 detrital apatite (U-Th)/He (AHe) and 100 apatite fission track (AFT) single-grain ages was presented from the modern outwash of the Tiedemann Glacier with catchment elevations between 530 and 3960 m. These data are combined with nine AHe and nine AFT bedrock ages collected from a ~2400 m vertical transect to test the hypotheses that erosion is uniformly or nonuniformly distributed in the catchment. A Monte Carlo sampling model and Kuiper statistical test are used to quantify the elevation range where outwash sediment is sourced. Model results from the AHe data suggest nearly uniform erosion in the catchment, with a preference for sediment being sourced from ~2900 to 2700 m elevation. Ages indicated that the largest source of sediment is near the present-day ELA. These results demonstrate the utility of AHe detrital thermochronology (and to a lesser degree AFT data) to quantify the distribution of erosion by individual geomorphic processes, as well as some of the limitations of the technique.

  2. Phytotoxic substances in runoff from forested catchment areas

    NASA Astrophysics Data System (ADS)

    Grimvall, Anders; Bengtsson, Maj-Britt; Borén, Hans; Wahlström, Dan

    Runoff from different catchment areas in southern Sweden was tested in a root bioassay based on solution cultures of cucumber seedlings. Water samples from agricultural catchment areas produced no signs at all or only weak signs of inhibited root growth, whereas several water samples from catchment areas dominated by mires or coniferous forests produced visible root injuries. The most severe root injuries (very short roots, discolouration, swelling of root tips and lack of root hairs) were caused by samples from a catchment area without local emissions and dominated by old stands of spruce. Fractionation by ultrafiltration showed that the phytotoxic effect of these samples could be attributed to organic matter with a nominal molecular-weight exceeding 1000 or to substances associated with organic macromolecules. Experiments aimed at concentrating phytotoxic compounds from surface water indicated that the observed growth inhibition was caused by strongly hydrophilic substances. Previous reports on phytotoxic, organic substances of natural origin have emphasized interaction between plants growing close together. The presence of phytotoxic substances in runoff indicates that there is also a large-scale dispersion of such compounds.

  3. Kresoxim methyl deposition, drift and runoff in a vineyard catchment.

    PubMed

    Lefrancq, M; Imfeld, G; Payraudeau, S; Millet, M

    2013-01-01

    Surface runoff and spray drift represent a primary mode of pesticide mobilisation from agricultural land to ecosystem. Though pesticide drift has mainly been studied at small scale (<1 ha), pesticide transports by drift and runoff have rarely been compared in the same agricultural catchment. Here kresoxim methyl (KM) drift during foliar application was evaluated in a vineyard catchment (Rouffach, Alsace, France), and KM deposition on non-target surfaces was compared to KM runoff. KM was detected on 55% of the collectors and concentration reached 18% of the applied dose (i.e. 1.5 mg m(-2)). Our results indicated that KM soil deposition greatly varied in space and time. The total KM soil deposition in the vineyard plots was estimated by four different interpolation methods (arithmetic mean, Thiessen method, inverse weighting distance and ordinary kriging) and ranged between 53 g and 61 g (5.8 and 6.6% of the total mass applied). The amount of KM drifted on roads was 50 times larger than that in runoff water collected at the outlet of the catchment. Although KM application was carried out under regular operational and climatic conditions, its deposition on non-target surfaces may be significant and lead to pesticide runoff. These results can be anticipated as a starting point for assessing pesticide deposition during spray application and corresponding pesticide runoff in agricultural catchments.

  4. Sediment dynamics in an overland flow-prone forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Alexander; Elsenbeer, Helmut

    2010-05-01

    Vegetation controls erosion in many respects, and it is assumed that forest cover is an effective control. Currently, most literature on erosion processes in forest ecosystems support this impression and estimates of sediment export from forested catchments serve as benchmarks to evaluate erosion processes under different land uses. Where soil properties favor near-surface flow paths, however, vegetation may not mitigate surface erosion. In the forested portion of the Panama Canal watershed overland flow is widespread and occurs frequently, and indications of active sediment transport are hard to overlook. In this area we selected a 9.7 ha catchment for a high-resolution study of suspended sediment dynamics. We equipped five nested catchments to elucidate sources, drivers, magnitude and timing of suspended sediment export by continuous monitoring of overland flow and stream flow and by simultaneous, event-based sediment sampling. The support program included monitoring throughfall, splash erosion, overland-flow connectivity and a survey of infiltrability, permeability, and aggregate stability. This dataset allowed a comprehensive view on erosion processes. We found that overland flow controls the suspended-sediment dynamics in channels. Particularly, rainfalls of high intensity at the end of the rainy season have a superior impact on the overall sediment export. During these events, overland flow occurs catchment-wide up to the divide and so does erosion. With our contribution we seek to provide evidence that forest cover and large sediment yields are no contradiction in terms even in the absence of mass movements.

  5. School Catchment Area Evasion: The Case of Berlin, Germany

    ERIC Educational Resources Information Center

    Noreisch, Kathleen

    2007-01-01

    This paper seeks to examine the ways in which school segregation plays out in a pure catchment area system and to what extent residential composition is directly mirrored in schools. The research examines the data for the districts in Berlin and, more specifically at the school level, for the district of Tempelhof-Schoneberg. The research is based…

  6. Seasonal exports of phosphorus from intensively fertilised nested grassland catchments.

    PubMed

    Lewis, Ciaran; Rafique, Rashad; Foley, Nelius; Leahy, Paul; Morgan, Gerard; Albertson, John; Kumar, Sandeep; Kiely, Gerard

    2013-09-01

    We carried out a one year (2002) study of phosphorus (P) loss from soil to water in three nested grassland catchments with known P input in chemical fertilizer and animal liquid slurry applications. Chemical fertilizer was applied to the grasslands between March and September and animal slurry was applied over the twelve months. The annual chemical P fertilizer applications for the 17 and 211 ha catchments were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha, respectively. The annual total phosphorus (TP) export in stream-flow was 2.61, 2.48 and 1.61 kg P/ha for the 17, 211 and 1524 ha catchments, respectively, compared with a maximum permissible (by regulation) annual export of ca. 0.35 kg P/ha. The export rate (ratio of P export to P in land applications) was 9.6% and 6.6% from the 17 and 211 ha catchments, respectively. On average, 70% of stream flow and 85% of the P export occurred during the five wet months (October to February) indicating that when precipitation is much greater than evaporation, the hydrological conditions are most favourable for P export. However the soil quality and land use history may vary the results. Particulate P made up 22%, 43% and 37% of the TP export at the 17, 211 and 1524 ha catchment areas, respectively. As the chemical fertilizer was spread during the grass growth months (March to September), it has less immediate impact on stream water quality than the slurry applications. We also show that as the catchment scale increases, the P concentrations and P export decrease, confirming dilution due to increasing rural catchment size. In the longer term, the excess P from fertilizer maintains high soil P levels, an antecedent condition favourable to P loss from soil to water. This study confirms the significant negative water quality impact of excess P applications, particularly liquid animal slurry applications in wet winter months. The findings suggest that restricted P application in

  7. Tritium-based age/streamflow relationships and catchment function

    NASA Astrophysics Data System (ADS)

    Stewart, M. K.; Morgenstern, U.

    2013-12-01

    Understanding runoff generation is important for management of freshwater systems. Determining transit time distributions (TTDs) of streamwaters and how they change with flow gives information on the flowpaths and water storages in catchments - fundamental for understanding the responses of streams to stressors such as pollution, land use change and climate change. This work uses tritium measurements on single samples to determine TTDs and how they change with flow. Such use of tritium is only practical so far in the Southern Hemisphere, because of its much-lower input of bomb-tritium in the 1960s. Another advantage of tritium is that it reveals the full spectrum of ages present in streams, whereas oxygen-18 or chloride variations only show younger ages (i.e. truncated TTDs). Case studies are presented for two New Zealand catchments, both with volcanic ash substrates. The first (Toenepi) is a dairy catchment near Hamilton, which shows well-constrained power law relationships between mean transit time (MTT) and flow, and between silica concentration and flow. Baseflow MTTs vary from 2.5 to 157 years. The second (Tutaeuaua) is a pastoral farming catchment near Taupo. Results for nested catchments along the stream also show power law relationships for both MTT and silica with flow. Baseflow MTTs vary from 1 to 11 years. Although the MTT data could be represented approximately by straight lines in log-log plots, hysteresis effects due to catchment wetness variations did disturb the relationships. Having TTDs from individual samples focusses attention on the nature of the water storages supplying the stream at the times of sampling. The flow record contains information on catchment function, which can enhance the value of the age data, provided such information can be satisfactorily interpreted. A new baseflow estimation method is used to determine the slow storage (aka groundwater) fraction in the stream. The age data is showing that slow storages have mean ages of

  8. Understanding catchment scale sediment sources using geochemical tracers

    NASA Astrophysics Data System (ADS)

    Ferreira, Carla S. S.; Walsh, Rory P. D.; Shakesby, Richard A.; Steenhuis, Tammo S.; Ferreira, António J. D.; Coelho, Celeste O. A.

    2013-04-01

    It is well-established that urbanization leads to increased erosion (at least locally) as well as enhanced overland flow and streamflow peaks. Less is known about how the spatial distribution of erosion sources and scale of increases in erosion vary with the nature of urbanization in different climatic and socio-economic settings. This is important in order to prevent or reduce adverse impacts of erosion on downstream sedimentation, channel siltation and shifting, and river pollution. This paper adopts a sediment fingerprinting approach to assess the impact of partial urbanization and associated land-use change on sediment sources within a peri-urban catchment (6 km2), Ribeira dos Covões on the outskirts of the city of Coimbra in central Portugal. Urban land-use has increased from just 6% in 1958 to 30% in 2009. The urban pattern includes some well-defined urban residential centres, but also areas of discontinuous urban sprawl, including educational, health and small industrial facilities, numerous new roads and an enterprise park is under construction on the upper part of the catchment. The catchment has a wet Mediterranean climate and the lithology comprises sandstone in the west and limestone in the east. Soil depth is generally >40cm. The average slope angle is 8° (maximum 47°). Altitude ranges from 30m to 205m. A sediment fingerprinting approach was adopted to help establish the relative importance of sediment inputs from different urban areas. During September 2012 current bed-sediment samples (0-3 cm depth) were collected from 11 channel sites along the main stream and in different tributaries. At sites where bed-sediment was deeper, additional samples were taken at 3cm intervals to a maximum depth of around 42cm. In addition, overbank sediment samples (0-3cm depth) were collected at 11 locations around the catchment. All samples were oven-dried (at 38°C) and different particle size fractions (0.125-2mm, 0.063-0.125mm and <0.063mm) obtained, where the <0

  9. A novel modelling framework to prioritize estimation of non-point source pollution parameters for quantifying pollutant origin and discharge in urban catchments.

    PubMed

    Fraga, I; Charters, F J; O'Sullivan, A D; Cochrane, T A

    2016-02-01

    Stormwater runoff in urban catchments contains heavy metals (zinc, copper, lead) and suspended solids (TSS) which can substantially degrade urban waterways. To identify these pollutant sources and quantify their loads the MEDUSA (Modelled Estimates of Discharges for Urban Stormwater Assessments) modelling framework was developed. The model quantifies pollutant build-up and wash-off from individual impervious roof, road and car park surfaces for individual rain events, incorporating differences in pollutant dynamics between surface types and rainfall characteristics. This requires delineating all impervious surfaces and their material types, the drainage network, rainfall characteristics and coefficients for the pollutant dynamics equations. An example application of the model to a small urban catchment demonstrates how the model can be used to identify the magnitude of pollutant loads, their spatial origin and the response of the catchment to changes in specific rainfall characteristics. A sensitivity analysis then identifies the key parameters influencing each pollutant load within the stormwater given the catchment characteristics, which allows development of a targeted calibration process that will enhance the certainty of the model outputs, while minimizing the data collection required for effective calibration. A detailed explanation of the modelling framework and pre-calibration sensitivity analysis is presented.

  10. Ecosystem processes at the watershed scale: Geomorphic patterns and stability of forest catchment water, energy and nitrogen use efficiency in the southern Appalachians

    NASA Astrophysics Data System (ADS)

    Band, L. E.; Hwang, T.; Hales, T. C.; Ford, C. R.

    2012-12-01

    Since the classic work by Hack in Goodlett in 1960, it has been recognized that there is a close coupling of geomorphic, forest ecosystem and soil development in humid mountainous catchments, with the magnitude and frequency of mass wasting events. In the southern Appalachians of the southeast United States, dense forest cover limits erosion and sediment transport during moderate events in undisturbed catchments, with most sediment delivery to streams by mass wasting processes, including the interaction of diffusive processes (soil creep) and debris avalanches. We hypothesize that debris avalanches are frequently triggered in a zone with moderate concavity at the head or just above hollows where a critical combination of sufficient gradient, colluvial soil accumulation, storm throughflow convergence and canopy root strength are achieved. The forest ecosystem adjusts patterns of foliar and root biomass in response to accessible light, water and nutrient resources, which are in turn conditioned by hydroclimate and geomorphically mediated flowpath and transport dynamics. Long term adjustment of drainage network form and density by colluvial and fluvial transport mass budgets provide slowly varying boundary conditions to hillslope hydrologic and geomorphic dynamics. We use a combination of detailed empirical observations and simulation modeling of coupled ecosystem, hydroclimate and geomorphic systems to derive the co-evolution of patterns of forest catchment water, energy and nutrient use efficiency, and the stability and response catchment form to long and short term climate perturbations.

  11. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

  12. Influence of catchment-scale military land use on stream physical and organic matter variables in small Southeaster Plains Catchments (USA)

    SciTech Connect

    Maloney, Kelly

    2005-01-01

    We conducted a 3-year study designed to examine the relationship between disturbance from military land use and stream physical and organic matter variables within 12 small (<5.5 km2) Southeastern Plains catchments at the Fort Benning Military Installation, Georgia, USA. Primary land-use categories were based on percentages of bare ground and road cover and nonforested land (grasslands, sparse vegetation, shrublands, fields) in catchments and natural catchments features, including soils (% sandy soils) and catchment size (area). We quantified stream flashiness (determined by slope of recession limbs of storm hydrographs), streambed instability (measured by relative changes in bed height over time), organic matter storage [coarse wood debris (CWD) relative abundance, benthic particulate organic matter (BPOM)] and stream-water dissolved organic carbon concentration (DOC). Stream flashiness was positively correlated with average storm magnitude and percent of the catchment with sandy soil, whereas streambed instability was related to percent of the catchment containing nonforested (disturbed) land. The proportions of in-stream CWD and sediment BPOM, and stream-water DOC were negatively related to the percent of bare ground and road cover in catchments. Collectively, our results suggest that the amount of catchment disturbance causing denuded vegetation and exposed, mobile soil is (1) a key terrestrial influence on stream geomorphology and hydrology and (2) a greater determinant of in-stream organic matter conditions than is natural geomorphic or topographic variation (catchment size, soil type) in these systems.

  13. Influence of catchment-scale military land use on stream physical and organic matter variables in small southeastern plains catchments (USA).

    PubMed

    Maloney, Kelly O; Mulholland, Patrick J; Feminella, Jack W

    2005-05-01

    We conducted a 3-year study designed to examine the relationship between disturbance from military land use and stream physical and organic matter variables within 12 small (<5.5 km2) Southeastern Plains catchments at the Fort Benning Military Installation, Georgia, USA. Primary land-use categories were based on percentages of bare ground and road cover and nonforested land (grasslands, sparse vegetation, shrublands, fields) in catchments and natural catchments features, including soils (% sandy soils) and catchment size (area). We quantified stream flashiness (determined by slope of recession limbs of storm hydrographs), streambed instability (measured by relative changes in bed height over time), organic matter storage [coarse wood debris (CWD) relative abundance, benthic particulate organic matter (BPOM)] and stream-water dissolved organic carbon concentration (DOC). Stream flashiness was positively correlated with average storm magnitude and percent of the catchment with sandy soil, whereas streambed instability was related to percent of the catchment containing nonforested (disturbed) land. The proportions of in-stream CWD and sediment BPOM, and stream-water DOC were negatively related to the percent of bare ground and road cover in catchments. Collectively, our results suggest that the amount of catchment disturbance causing denuded vegetation and exposed, mobile soil is (1) a key terrestrial influence on stream geomorphology and hydrology and (2) a greater determinant of in-stream organic matter conditions than is natural geomorphic or topographic variation (catchment size, soil type) in these systems.

  14. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

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

  16. Controls on Water Storage, Mixing and Release in a Nested Catchment Set-up with Clean and Mixed Physiographic Characteristics

    NASA Astrophysics Data System (ADS)

    Pfister, L.; McDonnell, J.; Hissler, C.; Martínez-Carreras, N.; Klaus, J.

    2015-12-01

    With catchment water storage being only rarely determined, storage dynamics remain largely unknown to date. However, storage bears considerable potential for catchment inter-comparison exercises, as well as it is likely to have an important role in regulating catchment functions. Catchment comparisons across a wide range of environments and scales will help to increase our understanding of relationships between storage dynamics and catchment processes. With respect to the potential of catchment storage for bringing new momentum to catchment classification and catchment processes understanding we currently investigate spatial and temporal variability of dynamic storage in a nested catchment set-up (16 catchments) of the Alzette River basin (Luxembourg, Europe), covering a wide range of geological settings, catchment areas, contrasted landuse, and hydro-meteorological and tracer series. We define catchment storage as the total amount of water stored in a control volume, delimited by the catchment's topographical boundaries and depth of saturated and unsaturated zones. Complementary storage assessments (via input-output dynamics of natural tracers, geographical sounding, groundwater level measurements, soil moisture measurements, hydrometry) are carried out for comparison purposes. In our nested catchment set-up we have (1) assessed dependencies between geology, catchment permeability and winter runoff coefficients, (2) calculated water balance derived catchment storage and mixing potential and quantified how dynamic storage differs between catchments and scales, and (3) examined how stream baseflow dD (as a proxy for baseflow transit time) and integrated flow measures (like the flow duration curve) relate to bedrock geology. Catchments with higher bedrock permeability exhibited larger storage capacities and eventually lower average winter runoff coefficients. Over a time-span of 11 years, all catchments re-produced the same winter runoff coefficients year after year

  17. A simplified rainfall-runoff stochastic simulation method for an application of the SCHADEX method to ungauged catchments.

    NASA Astrophysics Data System (ADS)

    Penot, David; Paquet, Emmanuel; Lang, Michel

    2014-05-01

    French catchments and its capacity to represent the asymptotic behaviour of the runoff distribution. References: K. J. Beven. Rainfall-Runoff modelling The Primer, British Library, 2003. F. Garavaglia, J. Gailhard, E. Paquet, M. Lang, R. Garçon, and P. Bernardara. Introducing a rainfall compound distribution model based on weather patterns sub-sampling. Hydrology and Earth System Sciences, 14(6):951-964, 2010. F. Gottardi, C. Obled, J. Gailhard, and E. Paquet. Statistical reanalysis of precipitation fields based on ground network data and weather patterns : Application over french mountains. Journal of Hydrology, 432-433:154-167, 2012. ISSN 0022-1694. E. Paquet, F. Garavaglia, R Garçon, and J. Gailhard. The schadex method : a semi-continuous rainfall-runoff simulation for extreme flood estimation. Journal of Hydrology, 2013. USDA SCS, National Engineering Handbook, Supplement A, Section 4, Chapter 10. Whashington DC, 1985.

  18. 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...

  19. PyCatch: catchment modelling in the PCRaster framework

    NASA Astrophysics Data System (ADS)

    Karssenberg, Derek; Lana-Renault, Noemí; Schmitz, Oliver

    2015-04-01

    PCRaster is an open source software framework for the construction and execution of stochastic, spatio-temporal, forward, models. It provides a large number of spatial operations on raster maps, with an emphasis on operations that are capable of transporting material (water, sediment) over a drainage network. These operations have been written in C++ and are provided to the model builder as Python functions. Models are constructed by combining these functions in a Python script. To ease implementation of models that use time steps and Monte Carlo iterations, the software comes with a Python framework providing control flow for temporal modelling and Monte Carlo simulation, including options for Bayesian data assimilation (Ensemble Kalman Filter, Particle Filter). A sophisticated visualization tool is provided capable of visualizing, animating, and exploring stochastic, spatio-temporal input or model output data. PCRaster is used for construction of for instance hydrological models (hillslope to global scale), land use change models, and geomorphological models. It is still being improved upon, for instance by adding under the hood functionality for executing models on multiple CPU cores, and by adding components for agent-based and network simulation. The software runs in MS Windows and Linux and is available at http://www.pcraster.eu. We provide an extensive set of online course materials (partly available free of charge). Using the PCRaster software framework, we recently developed the PyCatch model components for hydrological modelling and land degradation modelling at catchment scale. The PyCatch components run at time steps of seconds to weeks, and grid cell sizes of approximately 1-100 m, which can be selected depending on the case study for which PyCatch is used. Hydrological components currently implemented include classes for simulation of incoming solar radiation, evapotranspiration (Penman-Monteith), surface storage, infiltration (Green and Ampt

  20. Decadal changes in the frequency of major floods in near-natural catchments across North America and Europe

    NASA Astrophysics Data System (ADS)

    Hodgkins, Glenn A.; Hannaford, Jamie; Whitfield, Paul H.; Burn, Donald H.; Fleig, Anne; Stahl, Kerstin; Renard, Benjamin; Korhonen, Johanna; Murphy, Conor; Crochet, Philippe; Wilson, Donna; Madsen, Henrik

    2013-04-01

    Recent major floods in North America and Europe have received much press, with some concluding that these floods are more frequent in recent years as a result of anthropogenic warming. There has therefore been considerable scientific effort invested in establishing whether observed flood records show evidence of trends or variability in flood frequency, and to determine whether these patterns can be linked to climatic changes. However, the river catchments used in many published studies are influenced by direct human alteration such as reservoir regulation and urbanisation, which can confound the interpretation of climate-driven variability. Furthermore, a majority of previous studies have analysed changes in low magnitude floods, such as the annual peak flow, at a national scale. Few studies are known that have analysed changes in large floods (greater than 25-year floods) on a continental scale. To fill this research gap, the current study is analysing flood flows from reference hydrologic networks (RHNs) or RHN-like gauges across a large study domain embracing North America and much of Europe. RHNs comprise gauging stations with minimally disturbed catchment conditions, which have a near-natural flow regime and provide good quality data; RHN analyses thus allow hydro-climatic variability to be distinguished from direct artificial disturbances or data inhomogeneities. One of the key innovations in this study is the definition of an RHN-like network on a continental scale. The network incorporates existing, well-established RHNs in Canada, the US, the UK, Ireland and Norway, alongside RHN-like catchments from Europe (France, Switzerland, Iceland, Denmark, Sweden, Finland), which have been incorporated in the network following a major effort to ensure RHN-like status of candidate gauges through consultation with local experts. As the aim of the study is to examine long-term variability in the number of major floods, annual exceedances of 25-, 50-, and 100-year

  1. Sediment budget for Rediu reservoir catchment, North-Eastern Romania

    NASA Astrophysics Data System (ADS)

    Todosi, Cristian; Niculita, Mihai

    2016-04-01

    Sediment budgets are a useful tool for geomorphologic analysis, catchment management and environmental assessment, despite the uncertainties related to their assessment. We present the sediment budget construction and validation for a small catchment of 9.5319 kmp (953.19 ha) situated in the North-Eastern part of Romania. The Rediu reservoir was built between 1986 and 1988, on Rediu valley, a left tributary of Bahlui river, north-west from Iasi city. The catchment of the reservoir has 6.5 km in length and 2.5 km in maximum width, the altitudes decreasing from 170 m in the northern part, to 52 m in the southern part. The valley is symmetric, the altitude of the hillslopes going between 200 m to 75 m in one km length, in the transversal section with the maximum width. The floodplain is narrow having between 20 m to 210 m (in the area of confluence with Breazu tributary). The mean slope of the catchment is 6.4 degree, the maximum slope being 24.6 degrees. The length of channels which show banks of up to 2 m is 19.98 km. The land is used predominantly as crops (58.1 %), 16.7 % being covered by pastures (from which over half are eroded), 11.5 % percent of the catchment being covered by planted forests, 9.2 % by rural constructions and roads, 2.9 % by hayfields, 1.5 % by lakes and 0.1 % by orchards. Beside the Rediu reservoir, there are three ponds (15 771, 1761 and 751 sqm) in the catchment. We considered the trap efficiency for the reservoir and the ponds to be 95%. Aerial images from 1963, 1978 , 1984, 2005, 2008, 2010, 2012 and 2014 were used to assess the state of geomorphological processes before and after the reservoir construction. After 1970 a gully system situated in Breazu tributary sub-catchment and several active landslides along the main valley left side were forested. Beside these processes, soil erosion and human impact by constructions are the main processes generating sediment in the study area. The sediment yields were quantified by estimating the

  2. Interpolation of daily precipitation in mountain catchments with limited data availability

    NASA Astrophysics Data System (ADS)

    Jacquin, Alexandra

    2014-05-01

    Statistical properties of precipitation in mountain catchments are likely to be heterogeneous, due to the effect of orography. The interpolation of precipitation gauge data in these cases requires the application of methods that are able to account for the existence of a spatial trend in the expectation of precipitation. Most studies in this subject have used data from regions with relatively dense meteorological networks and the question of what interpolation methods can provide more reliable results in mountain catchments with limited data availability is largely unexplored. This study evaluates the applicability of the techniques kriging with external drift (KED) and optimal interpolation method (OIM) in this scenario. The Thiessen polygons (TP) method is used as a benchmark. The study area is located in the upper Aconcagua River catchment, in Central Chile. Daily data spanning a period of ten years, from nine stations located between 640[m.a.s.l.] and 2765[m.a.s.l.], are used. Given that precipitation in the area is seasonal with respect to both precipitation amounts and their spatial dependence structure, data from each month of the year are treated separately. Aconcagua at Chacabuquito sub-catchment, with an area of 2110[Km2] and elevation ranging from 950[m.a.s.l.] to 5930[m.a.s.l.], is used as a case study. KED and OIM incorporate the information on the spatial trend of daily precipitation differently. KED postulates that the function that defines the expectation of precipitation at each location is a linear combination of basis function of known type. Preliminary analysis revealed that a logarithmic relationship between the expectation of daily precipitation and elevation was appropriate. The application of the OIM requires prior estimation of both the expectation and the standard deviation of precipitation at the location of interest. For this purpose, logarithmic relationships between long-term mean precipitation and elevation, and between sample

  3. Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach

    USGS Publications Warehouse

    Hassan, S.M. Tanvir; Lubczynski, Maciek W.; Niswonger, Richard G.; Zhongbo, Su

    2014-01-01

    The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using 18 years of daily groundwater head and stream discharge data to evaluate the surface–groundwater interactions in semi-arid, ∼80 km2 granitic Sardon hilly catchment in Spain characterized by shallow water table conditions, relatively low storage, dense drainage networks and frequent, high intensity rainfall. The following hydrological observations for the Sardon Catchment, and more generally for HRSs were made: (i) significant bi-directional vertical flows occur between surface water and groundwater throughout the HRSs; (ii) relatively large groundwater recharge represents 16% of precipitation (P, 562 mm.y−1) and large groundwater exfiltration (∼11% of P) results in short groundwater flow paths due to a dense network of streams, low permeability and hilly topographic relief; deep, long groundwater flow paths constitute a smaller component of the water budget (∼1% of P); quite high groundwater evapotranspiration (∼5% of P and ∼7% of total evapotranspiration); low permeability and shallow soils are the main reasons for relatively large components of Hortonian flow and interflow (15% and 11% of P, respectively); (iii) the majority of drainage from the catchment leaves as surface water; (iv) declining 18 years trend (4.44 mm.y−1) of groundwater storage; and (v) large spatio-temporal variability of water fluxes. This IHM study of HRSs provides greater understanding of these relatively unknown hydrologic systems that are widespread throughout the world and are important for water resources in many regions.

  4. Tracer Cycles and Water Ages in Heterogeneous Catchments and Aquifers

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.; Jasechko, S.

    2015-12-01

    Estimates of catchment mean transit times are often based on seasonal cycles of stable isotope tracers in precipitation and streamflow. In many cases these transit time estimates are derived directly from sine-wave fitting to the observed seasonal isotope cycles. Broadly similar results are also obtained from time-domain convolutions or explicit tracer modeling, because here too the dominant tracer signal that these techniques seek to match is the seasonal isotopic cycle. Here I use simple benchmark tests to show that estimates of mean transit times based on seasonal tracer cycles will typically be wrong by several hundred percent, when applied to catchments with realistic degrees of spatial heterogeneity. This aggregation bias arises from the strong nonlinearity in the relationship between tracer cycle amplitude and mean travel time. A similar bias arises in estimates of mean transit times in nonstationary catchments. Since typical real-world catchments are both spatially heterogeneous and nonstationary, this analysis poses a fundamental challenge to tracer-based estimates of mean transit times. I propose an alternative storage metric, the fraction of "young water" in streamflow, defined as the fraction of runoff with transit times of less than roughly 0.2 years. I show that young water fractions are virtually free of aggregation bias; that is, they can be accurately estimated from tracer cycles in highly heterogeneous mixtures of subcatchments with strongly contrasting transit time distributions. They can also be reliably estimated in strongly nonstationary catchments. Young water fractions can be estimated separately for individual flow regimes, allowing direct determination of how shifts in hydraulic regime alter the fraction of water reaching the stream by fast flowpaths. One can also estimate the chemical composition of idealized "young water" and "old water" end-members, using relationships between young water fractions and solute concentrations across

  5. On the trail of 'hidden streamflow' in Luxembourgish catchments

    NASA Astrophysics Data System (ADS)

    Stewart, Michael; Pfister, Laurent; Morgenstern, Uwe; Martinez-Carreras, Nuria; Gourdol, Laurent; Klaus, Julian; McDonnell, Jeffrey

    2014-05-01

    Tritium measurements are being carried out in well-studied catchments in the Attert sub-basin of the Alzette River in Luxembourg to investigate transit times of baseflow from the various lithologies in the area. Rock-types vary from sandstone with high permeability to marl and schist with low permeabilities. In contrast to other methods, tritium reveals the full spectrum of ages present in streams including 'hidden streamflow' (i.e. water older than that measurable by stable isotope or conservative tracer methods) Stewart et al. (2012). In principle, it can also provide ages for individual samples and therefore reveal variations in age with flow if measurements are accurate enough. However, difficulties arise in determining the tritium input function and from ambiguous age solutions due to the past input of thermonuclear tritium. Previous and concurrent geochemical and stable isotope studies are providing complementary information about the systems (e.g. geological controls on catchment storage, mixing potential, isotopic signatures in streamflow) Pfister et al. (2014). Results to date are showing that old water with mean transit times of about 18 years flow from catchments dominated by sandstone at medium to low flows. These streams also have very homogeneous δD values at such flows showing large storages and mixing potentials. On the other hand, catchments dominated by marl and schist show varying mean transit times ranging from 2 to 20 years depending on flows, although data is limited. The δD values of these streams are scattered and have a decreasing trend with streamflow showing event and seasonal rainfall influence, and thus small storage capacities and mixing potentials. It appears that 'hidden streamflow' is alive and well, and living in Luxembourg! Pfister L. et al. 2014: Catchment storage, baseflow isotope signatures and basin geology: Is there a connection? In preparation. Stewart, M.K., Morgenstern, U., McDonnell, J.J., Pfister, L. 2012: The 'hidden

  6. Modeling sediment delivery from a highly erodible mountain catchment

    NASA Astrophysics Data System (ADS)

    Le Bouteiller, C.; Asif, N. M.; Recking, A.; Liebault, F.

    2015-12-01

    Draix observatory is located in the French Alps on a highly erodible substrate of shale. Most of the observatory is in a badland area characterized by steep gullies and high erosion rates (up to 1cm/year). Within the observatory, the study focuses on the Moulin, which is an 8ha catchment located at an elevation of 850-925m, with 54% of badland area. Available data includes DEM, meteorological data, high-frequency records of discharge and suspended sediment concentration during the floods, cumulative values of bedload transport for each flood, high-frequency records of bedload transport for a few events from a Birkbeck sampler. Modeling sediment delivery in such a catchment is challenging because 1) most available models have been designed for low-relief regions and do not account for steep slope processes such as debris flow and landslides; 2) hydrology (especially flashfloods) in mountainous regions is not well understood; 3) soil properties are very heterogeneous ; 4) multiple time scales are involved: seasonal sediment production on the slopes, storage in the bed and exportation requires to work on yearly times scales, while summer floods and most sediment delivery events occur over a few minutes only. We evaluate the ability of the SHETRAN model to reproduce sediment delivery patterns from the catchment. First, we calibrate the hydrological model using one year of meteorological and hydrological data. We then apply the sediment transport module over several flood events, using in-situ measurements of bed and slope grain-size distributions. Finally we investigate how sediment available on the slopes moves through the catchment over a year. Event-scale volumes of sediment simulated by the model are comparable to observed values within an order of 2. Sediment delivery rates are very sensitive to the slope grain-size distribution. Depending on sediment availability on the slopes and on soil erodibility, the catchment is running either in a supply-limited or

  7. Safeguarding the provision of ecosystem services in catchment systems.

    PubMed

    Everard, Mark

    2013-04-01

    A narrow technocentric focus on a few favored ecosystem services (generally provisioning services) has led to ecosystem degradation globally, including catchment systems and their capacities to support human well-being. Increasing recognition of the multiple benefits provided by ecosystems is slowly being translated into policy and some areas of practice, although there remains a significant shortfall in the incorporation of a systemic perspective into operation management and decision-making tools. Nevertheless, a range of ecosystem-based solutions to issues as diverse as flooding and green space provision in the urban environment offers hope for improving habitat and optimization of beneficial services. The value of catchment ecosystem processes and their associated services is also being increasingly recognized and internalized by the water industry, improving water quality and quantity through catchment land management rather than at greater expense in the treatment costs of contaminated water abstracted lower in catchments. Parallel recognition of the value of working with natural processes, rather than "defending" built assets when catchment hydrology is adversely affected by unsympathetic upstream development, is being progressively incorporated into flood risk management policy. This focus on wider catchment processes also yields a range of cobenefits for fishery, wildlife, amenity, flood risk, and other interests, which may be optimized if multiple stakeholders and their diverse value systems are included in decision-making processes. Ecosystem services, particularly implemented as a central element of the ecosystem approach, provide an integrated framework for building in these different perspectives and values, many of them formerly excluded, into commercial and resource management decision-making processes, thereby making tractable the integrative aspirations of sustainable development. This can help redress deeply entrenched inherited assumptions

  8. Problems with heterogeneity in physically based agricultural catchment models

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  9. Assessing water quality trends in catchments with contrasting hydrological regimes

    NASA Astrophysics Data System (ADS)

    Sherriff, Sophie C.; Shore, Mairead; Mellander, Per-Erik

    2016-04-01

    Environmental resources are under increasing pressure to simultaneously achieve social, economic and ecological aims. Increasing demand for food production, for example, has expanded and intensified agricultural systems globally. In turn, greater risks of diffuse pollutant delivery (suspended sediment (SS) and Phosphorus (P)) from land to water due to higher stocking densities, fertilisation rates and soil erodibility has been attributed to deterioration of chemical and ecological quality of aquatic ecosystems. Development of sustainable and resilient management strategies for agro-ecosystems must detect and consider the impact of land use disturbance on water quality over time. However, assessment of multiple monitoring sites over a region is challenged by hydro-climatic fluctuations and the propagation of events through catchments with contrasting hydrological regimes. Simple water quality metrics, for example, flow-weighted pollutant exports have potential to normalise the impact of catchment hydrology and better identify water quality fluctuations due to land use and short-term climate fluctuations. This paper assesses the utility of flow-weighted water quality metrics to evaluate periods and causes of critical pollutant transfer. Sub-hourly water quality (SS and P) and discharge data were collected from hydrometric monitoring stations at the outlets of five small (~10 km2) agricultural catchments in Ireland. Catchments possess contrasting land uses (predominantly grassland or arable) and soil drainage (poorly, moderately or well drained) characteristics. Flow-weighted water quality metrics were calculated and evaluated according to fluctuations in source pressure and rainfall. Flow-weighted water quality metrics successfully identified fluctuations in pollutant export which could be attributed to land use changes through the agricultural calendar, i.e., groundcover fluctuations. In particular, catchments with predominantly poor or moderate soil drainage

  10. Catchment travel time distributions and water flow in soils

    NASA Astrophysics Data System (ADS)

    Rinaldo, A.; Beven, K. J.; Bertuzzo, E.; Nicotina, L.; Davies, J.; Fiori, A.; Russo, D.; Botter, G.

    2011-07-01

    Many details about the flow of water in soils in a hillslope are unknowable given current technologies. One way of learning about the bulk effects of water velocity distributions on hillslopes is through the use of tracers. However, this paper will demonstrate that the interpretation of tracer information needs to become more sophisticated. The paper reviews, and complements with mathematical arguments and specific examples, theory and practice of the distribution(s) of the times water particles injected through rainfall spend traveling through a catchment up to a control section (i.e., "catchment" travel times). The relevance of the work is perceived to lie in the importance of the characterization of travel time distributions as fundamental descriptors of catchment water storage, flow pathway heterogeneity, sources of water in a catchment, and the chemistry of water flows through the control section. The paper aims to correct some common misconceptions used in analyses of travel time distributions. In particular, it stresses the conceptual and practical differences between the travel time distribution conditional on a given injection time (needed for rainfall-runoff transformations) and that conditional on a given sampling time at the outlet (as provided by isotopic dating techniques or tracer measurements), jointly with the differences of both with the residence time distributions of water particles in storage within the catchment at any time. These differences are defined precisely here, either through the results of different models or theoretically by using an extension of a classic theorem of dynamic controls. Specifically, we address different model results to highlight the features of travel times seen from different assumptions, in this case, exact solutions to a lumped model and numerical solutions of the 3-D flow and transport equations in variably saturated, physically heterogeneous catchment domains. Our results stress the individual characters of the

  11. Hydrological observation of the artificial catchment `Chicken Creek

    NASA Astrophysics Data System (ADS)

    Mazur, K.; Biemelt, D.; Schoenheinz, D.; Grünewald, U.

    2009-04-01

    In Lusatia, eastern Germany, an artificial catchment called 'Chicken Creek' was developed. The catchment with an area of 6 ha was designed as hillside on the top of a refilled open mining pit. The bottom boundary was created by a 1 to 2 m thick clay layer acting as aquiclude. The catchment body consists of a 2 to 4 m mighty layer of sandy to loamy sediments acting as aquifer. The catchment 'Chicken Creek' is the central investigation site of the German-Swiss Collaborative Research Centre SFB/TRR 38. The aim of the research is to characterise various ecosystem development phases with respect to the occurring relevant structures and processes. Therefore, structures and processes as well as interactions being dominant within the initial ecosystem development phase are investigated and will be compared to those occurring in the later stages of ecosystem development. In this context, one important part of the investigations is the detailed observation of hydrological processes and the determination of the water balance components. To achieve these objectives, a comprehensive monitoring programme was planned considering the following questions: Which parameters/data are required? Which parameters/data can be measured? Which spatial and temporal resolution of observations is required? The catchment was accordingly equipped with weirs, flumes, observation wells, probes and meteorological observation stations. First results were obtained and will be presented. The gathered data provide parameters and boundary conditions for the ensuing hydro(geo)logical modeling. Conclusions e.g. from groundwater flow simulations shall allow to improve theses about the dynamic in the saturated zone and support the quantification of the groundwater discharge as component of the water balance. First research results show that precipitation related surface runoff proves to be much more dominant in the hydrological system than initially expected. Therefore, the monitoring concept had to be

  12. 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

  13. 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

  14. Scale-dependent groundwater contributions influence patterns of winter baseflow stream chemistry in boreal catchments

    NASA Astrophysics Data System (ADS)

    Peralta-Tapia, Andrés.; Sponseller, Ryan A.; Šgren, Anneli; Tetzlaff, Doerthe; Soulsby, Chris; Laudon, Hjalmar

    2015-05-01

    Understanding how the sources of surface water change along river networks is an important challenge, with implications for soil-stream interactions, and our ability to predict hydrological and biogeochemical responses to environmental change. Network-scale patterns of stream water reflect distinct hydrological processes among headwater units, as well as variable contributions from deeper groundwater stores, which may vary nonlinearly with drainage basin size. Here we explore the spatial variability of groundwater inputs to streams, and the corresponding implications for surface water chemistry, during winter baseflow in a boreal river network. The relative contribution of recent and older groundwater was determined using stable isotopes of water (δ18O) at 78 locations ranging from small headwaters (0.12 km2) to fourth-order streams (68 km2) in combination with 79 precipitation and 10 deep groundwater samples. Results from a two end-member mixing model indicate that deeper groundwater inputs increased nonlinearly with drainage area, ranging from ~20% in smaller headwater subcatchments to 70-80% for catchments with a 10.6 km2 area or larger. Increases in the groundwater contribution were positively correlated to network-scale patterns in surface stream pH and base cation concentrations and negatively correlated to dissolved organic carbon. These trends in chemical variables are consistent with the production of weathering products and the mineralization of organic matter along groundwater flow paths. Together, the use of stable isotopes and biogeochemical markers illustrate how variation in hydrologic routing and groundwater contributions shape network-scale patterns in stream chemistry as well as patchiness in the relative sensitivity of streams to environmental change and perturbation.

  15. Land-use change impacts on hydrologic soil properties and implications for overland-flow in a periurban Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Ferreira, Carla S. S.; Steenhuis, Tammo S.; Walsh, Rory P. D.; Soares, Daniel; Ferreira, António J. D.; Coelho, Celeste O. A.

    2013-04-01

    Global urbanization affects land-use, soil properties and runoff generation and has implications on flow connectivity in the landscape. Understanding how various forms of the urban mosaic affects the landscape functioning is still a challenge. The aim of our research is to: 1) understand spatio-temporal variability of soil hydrological properties of land-uses in a periurban Mediterranean environment and the impacts on runoff processes; 2) assess the impacts of urbanizing mosaic features of periurban areas on flow connectivity and streamflow response. The study is carried out in a Portuguese typical urbanizing environment, the Ribeira dos Covões (6 km2 catchment). In the last 50 years, the catchment has changed from being rural into urban. By 2009, although still dominated by forest (66%), the catchment urban areas (30%) exhibited a distinctive pattern involving sets of gardens and walls, with derelict land in between properties. The study combines field surveys and hydrological monitoring to assess spatio-temporal dynamics of land-use contributions to surface hydrology. Over a one year period, nine monitoring campaigns were carried out to assess the variability of water-repellency, soil moisture and water infiltration in different land-use categories. In 2010 fall, nine 8mx2m runoff plots were installed in the forest areas, as well as a continuous-recording network that includes three rain-gauges and nine water-level recorders. This network provides continuous data on hydrological response to rainfall at the catchment outlet and in eight sub-catchments. The results revealed high spatio-temporal variability in soil hydrological properties with significant differences between land-uses. In summer, soil hydrophobicity is widespread and most severe in forest areas, resulting in very low soil-matrix infiltration and thereby promoting Hortonian overland-flow. In wet periods, water-repellency almost vanished, with infiltration rates at forest sites increasing to12mm

  16. Drought causes step-changes in catchment-scale carbon export from peatland catchments

    NASA Astrophysics Data System (ADS)

    Howden, Nicholas; Worrall, Fred; Burt, Tim

    2015-04-01

    Increases in fluvial DOC concentrations in world rivers, particularly those that drain areas of peatland, have been observed for some years, suggesting an increase in carbon loss from the terrestrial biosphere. But it has not been straightforward to identify what causes these increases due to a lack of long-term time series to characterise both observed DOC concentrations and potential drivers. The York Waterworks Company (York, UK) abstracted drinking water from the Yorkshire Ouse just upstream of the city from the late 1800s until 2002. During the period August 1945 to December 2002, records of monthly-average DOC concentrations were kept (using water colour as a surrogate). From January 2003 onwards, the Environment Agency of England and Wales (EA) continued the monitoring, thus providing a 68-year record of monthly-average DOC concentrations in the Yorkshire Ouse, which is the longest DOC time series ever reported for a catchment with significant peat cover. We use the Yorkshire Ouse DOC record to develop a new method that shows how changes in DOC concentration and river flow have influenced carbon fluxes in the Ouse for the latter half of the 20th century and show that the only major changes in DOC flux are caused by step-increases in concentration following severe drought. We then use this method to identify a similar effect in other DOC records for UK rivers. The results suggest that increases in DOC export are due more to discrete events than to the impact of continuous drivers (such as increasing temperatures or changing atmospheric deposition), and also show these increases not to be reversed for at least four decades.

  17. Models for fine-scale precipitation relevant to urban catchment applications

    NASA Astrophysics Data System (ADS)

    Onof, Chris; Ramesh, Nadarajah; Thayakaran, Rasiah

    2014-05-01

    There are a number of stochastic point process models that can be used to generate rainfall data at hourly or higher aggregation levels. For most hydrological applications rainfall data collected at these aggregation levels are sufficient. Nevertheless, for some catchment studies such as the analysis of urban drainage system, rainfall time series at finer resolution are required to make more accurate estimation of quantities of interest. Poisson cluster based stochastic models are capable of generating rainfall at hourly (or higher) aggregation levels. However for sub-hourly time scale, unless one uses 2 levels of clustering, one has to rely on stochastic disaggregation models to disaggregate hourly rainfall series simulated by cluster based models using either the Bartlett-Lewis or Neyman-Scott processes. This would involve combining two stochastic models which naturally increases the model uncertainty. In view of this, it is useful to have a single stochastic model which has the ability to generate rainfall time series at a finer as well as other time-scale of interest, and which is easier to fit than a Poisson-cluster model. Therefore, our aim in this study is to explore a class of doubly stochastic Poisson process models that can address this problem. For this class of stochastic precipitation models it is possible to write down the likelihood function and hence we use maximum likelihood methods to estimate parameters of the models. The proposed models are used to analyse rainfall bucket tip-times series over a network of stations in a catchment. These multi-site doubly stochastic point process models incorporate local covariate information in an attempt to capture the effect of atmospheric covariates on rainfall characteristics. The variables used in the analysis are elevation of the recording station above sea-level, local temperature, sea-level pressure and relative humidity. The performance of the models is assessed by comparing various statistical

  18. Recognising the Anthropocene at a Regional-Catchment Scale

    NASA Astrophysics Data System (ADS)

    Brown, Tony

    2014-05-01

    Recent reviews concerning the recognition of the Anthropocene in geomorphology have focussed on small to medium-sized catchments and have aggregated these studies to derive regional syntheses. However, the erosional and sedimentary responses to human activities vary both in nature and scale within regional-scale or medium to large catchments. Geomorphological responses also vary in their connectivity and this is, and will be, reflected in the residence time of Anthropogenic units and earth surface properties. This paper will explore the variation of anthropogenic responses in a medium-sized sedimentary basin (the Somerset Levels basin) which drains into the estuary of the River Severn in the UK. It will be shown that different human activities at different dates, and driven by very different socio-economic factors, interact and change geomorphic connectivity producing a palimpsest of anthropogenic geomorphic responses with highly variable surface expression and geochemical signatures.

  19. Overland flow generation in two lithologically distinct rainforest catchments

    USGS Publications Warehouse

    Godsey, S.; Elsenbeer, H.; Stallard, R.

    2004-01-01

    Streams on uniformly rainforest-covered, but lithologically very diverse Barro Colorado Island in central Panama?? show remarkable differences in their runoff response to rainfall. This lithological diversity is reflected in equally diverse soilscapes, and our objective was to test the hypothesis that contrasting runoff responses derive from soilscape features that control the generation of overland flow. We determined the soil saturated hydraulic conductivity (Ks) of two neighboring, but hydrologically contrasting catchments (Lutz Creek with a flashy and Conrad Trail with a delayed response to rainfall), and quantified the spatial and temporal frequency of overland flow occurrence. The median Ks values at a depth of 12.5 cm are large enough to rule out Hortonian overland flow, but a marked decrease in K s in Lutz Creek catchment at 30 cm suggests the formation of a perched water table and the generation saturation overland flow; the decrease in Ks in the Conrad Trail catchment is more gradual, and a perched water table is expected to form only at depths below 50 cm. In Lutz Creek, overland flow was generated frequently in time and space and regardless of topographic position, including near the interfluve, with very low thresholds of storm magnitude, duration, intensity and antecedent wetness, whereas in Conrad Trail, overland flow was generated much less frequently and then only locally. We conclude that soilscape features and microtopography are important controls of overland flow generation in these catchments. Our results contribute to the growing evidence that overland flow and forests are not a priori a contradiction in terms. ?? 2004 Elsevier B.V. All rights reserved.

  20. Factors controlling mercury transport in an upland forested catchment

    USGS Publications Warehouse

    Scherbatskoy, T.; Shanley, J.B.; Keeler, G.J.

    1998-01-01

    Total mercury (Hg) deposition and input/output relationships were investigated in an 11-ha deciduous forested catchment in northern Vermont as part of ongoing evaluations of rig cycling and transport in the Lake Champlain basin. Atmospheric Hg deposition (precipitation + modeled vapor phase downward flux) was 425 mg ha-1 during the one-year period March 1994 through February 1995 and 463 mg ha-1 from March 1995 through February 1996. In the same periods, stream export of total Hg was 32 mg ha-1 and 22 mg ha-1, respectively. Thus, there was a net retention of Hg by the catchment of 92% the first year and 95% the second year. In the first year, 16.9 mg ha-1 or about half of the annual stream export, occurred on the single day of peak spring snowmelt in April. In contrast, the maximum daily export in the second year, when peak stream flow was somewhat lower, was 3.5 mg ha-1 during a January thaw. The fate of file Hg retained by this forested catchment is not known. Dissolved (< 0.22 ??m) Hg concentrations in stream water ranged from 0.5-2.6 ng L-1, even when total (unfiltered) concentrations were greater than 10 ng L-1 during high flow events. Total Hg concentrations in stream water were correlated with the total organic fraction of suspended sediment, suggesting the importance of organic material in Hg transport within the catchment. High flow events and transport with organic material may be especially important mechanisms for the movement of Hg through forested ecosystems.

  1. Overland flow generation in two lithologically distinct rainforest catchments

    NASA Astrophysics Data System (ADS)

    Godsey, S.; Elsenbeer, H.; Stallard, R.

    2004-08-01

    Streams on uniformly rainforest-covered, but lithologically very diverse Barro Colorado Island in central Panamá show remarkable differences in their runoff response to rainfall. This lithological diversity is reflected in equally diverse soilscapes, and our objective was to test the hypothesis that contrasting runoff responses derive from soilscape features that control the generation of overland flow. We determined the soil saturated hydraulic conductivity ( Ks) of two neighboring, but hydrologically contrasting catchments (Lutz Creek with a flashy and Conrad Trail with a delayed response to rainfall), and quantified the spatial and temporal frequency of overland flow occurrence. The median Ks values at a depth of 12.5 cm are large enough to rule out Hortonian overland flow, but a marked decrease in Ks in Lutz Creek catchment at 30 cm suggests the formation of a perched water table and the generation saturation overland flow; the decrease in Ks in the Conrad Trail catchment is more gradual, and a perched water table is expected to form only at depths below 50 cm. In Lutz Creek, overland flow was generated frequently in time and space and regardless of topographic position, including near the interfluve, with very low thresholds of storm magnitude, duration, intensity and antecedent wetness, whereas in Conrad Trail, overland flow was generated much less frequently and then only locally. We conclude that soilscape features and microtopography are important controls of overland flow generation in these catchments. Our results contribute to the growing evidence that overland flow and forests are not a priori a contradiction in terms.

  2. Suspended sediment apportionment in a South-Korean mountain catchment

    NASA Astrophysics Data System (ADS)

    Birkholz, Axel; Meusburger, Katrin; Park, Ji-Hyung; Alewell, Christine

    2016-04-01

    Due to the rapid agricultural expansion and intensification during the last decades in South-Korea, large areas of hill slope forests were transformed to paddies and vegetable fields. The intensive agriculture and the easily erodible soils in our catchment are a major reason for the increased erosion causing suspended sediments to infiltrate into the close drinking water reservoir. The drinking water reservoir Lake Soyang provides water supply for over ten million people in Seoul. Landscape managers need to know the exact origin of these sediments before they can create landscape amelioration schemes. We applied a compound-specific stable isotope (CSSI) approach (Alewell et al., 2015) to apportion the sources of the suspended sediments between forest and agricultural soil contribution to the suspended sediments in a different catchment and applied the same approach to identify and quantify the different sources of the suspended sediments in the river(s) contributing to Lake Soyang. We sampled eight soil sites within the catchment considering the different landuse types forest, rice paddies, maize and vegetables. Suspended sediments were sampled at three outlets of the different sub-catchments. Soils and suspended sediments are analysed for bulk carbon and nitrogen isotopes, compound-specific carbon isotopes of plant-wax derived long-chain fatty acids and long-chain n-alkanes. Fatty acid and alkane isotopes are then used in mixing calculations and the mixing model software IsoSource to find out the contribution of the different source soils to the suspended sediments. We present first data of the source soils and the suspended sediments. C. Alewell, A. Birkholz, K. Meusburger, Y. Schindler-Wildhaber, L. Mabit, 2015. Sediment source attribution from multiple land use systems with CSIA. Biogeosciences Discuss. 12: 14245-14269.

  3. Geographically Isolated Wetlands and Catchment Hydrology: A Modified Model Analyses

    NASA Astrophysics Data System (ADS)

    Evenson, G.; Golden, H. E.; Lane, C.; D'Amico, E.

    2014-12-01

    Geographically isolated wetlands (GIWs), typically defined as depressional wetlands surrounded by uplands, support an array of hydrological and ecological processes. However, key research questions concerning the hydrological connectivity of GIWs and their impacts on downgradient surface waters remain unanswered. This is particularly important for regulation and management of these systems. For example, in the past decade United States Supreme Court decisions suggest that GIWs can be afforded protection if significant connectivity exists between these waters and traditional navigable waters. Here we developed a simulation procedure to quantify the effects of various spatial distributions of GIWs across the landscape on the downgradient hydrograph using a refined version of the Soil and Water Assessment Tool (SWAT), a catchment-scale hydrological simulation model. We modified the SWAT FORTRAN source code and employed an alternative hydrologic response unit (HRU) definition to facilitate an improved representation of GIW hydrologic processes and connectivity relationships to other surface waters, and to quantify their downgradient hydrological effects. We applied the modified SWAT model to an ~ 202 km2 catchment in the Coastal Plain of North Carolina, USA, exhibiting a substantial population of mapped GIWs. Results from our series of GIW distribution scenarios suggest that: (1) Our representation of GIWs within SWAT conforms to field-based characterizations of regional GIWs in most respects; (2) GIWs exhibit substantial seasonally-dependent effects upon downgradient base flow; (3) GIWs mitigate peak flows, particularly following high rainfall events; and (4) The presence of GIWs on the landscape impacts the catchment water balance (e.g., by increasing groundwater outflows). Our outcomes support the hypothesis that GIWs have an important catchment-scale effect on downgradient streamflow.

  4. Relationship between the elemental composition of stream biofilms and water chemistry-a catchment approach.

    PubMed

    Kamjunke, Norbert; Mages, Margarete; Büttner, Olaf; Marcus, Hanna; Weitere, Markus

    2015-07-01

    As benthic biofilms mediate essential functions in stream ecosystems (e.g., carbon flux, storage of nutrients and other substances), the element-specific regulation of the biofilm composition is of great interest. We tested whether (1) the elemental composition of biofilms is related to that of the water column and (2) there are different accumulation patterns from the dissolved phase (adsorption) and the particulate phase (incorporation of suspended matter). We analysed biomass parameters, nutrients and metals in biofilms and surface waters at 28 sites within a stream network (Bode catchment, Germany). Algal biomass in biofilms was dominated by diatoms. The P/C ratio in biofilms was positively related to total phosphorus of surface water (and to the proportion of agricultural area in the catchment) indicating phosphorus limitation of biofilms, whereas the N/C ratio was not related to nitrate levels of surface water, and neither the P/C nor the N/C ratio to the concentration of dissolved organic carbon (DOC) of surface water. Biofilms were enriched in metals compared to their concentrations in water. The metals in biofilms were positively related to the concentration of dissolved metals in surface water for iron and strontium (but not for manganese, copper, zinc, arsenic or lead) and to the concentrations of particle-associated metals of surface waters for strontium and lead. Manganese and arsenic were the metals with a negative effect on the biomasses of biofilm diatoms and cyanobacteria. Overall, we observed element-specific accumulation patterns in biofilms with selected elements being related to the water column while others were probably subject to biofilm-internal processes.

  5. Evaluating nitrogen removal by vegetation uptake using satellite image time series in riparian catchments.

    PubMed

    Wang, Xuelei; Wang, Qiao; Yang, Shengtian; Zheng, Donghai; Wu, Chuanqing; Mannaerts, C M

    2011-06-01

    Nitrogen (N) removal by vegetation uptake is one of the most important functions of riparian buffer zones in preventing non-point source pollution (NSP), and many studies about N uptake at the river reach scale have proven the effectiveness of plants in controlling nutrient pollution. However, at the watershed level, the riparian zones form dendritic networks and, as such, may be the predominant spatially structured feature in catchments and landscapes. Thus, assessing the functions of riparian system at the basin scale is important. In this study, a new method coupling remote sensing and ecological models was used to assess the N removal by riparian vegetation on a large spatial scale. The study site is located around the Guanting reservoir in Beijing, China, which was abandoned as the source water system for Beijing due to serious NSP in 1997. SPOT 5 data was used to map the land cover, and Landsat-5 TM time series images were used to retrieve land surface parameters. A modified forest nutrient cycling and biomass model (ForNBM) was used to simulate N removal, and the modified net primary productivity (NPP) module was driven by remote sensing image time series. Besides the remote sensing data, the necessary database included meteorological data, soil chemical and physical data and plant nutrient data. Pot and plot experiments were used to calibrate and validate the simulations. Our study has proven that, by coupling remote sensing data and parameters retrieval techniques to plant growth process models, catchment scale estimations of nitrogen uptake rates can be improved by spatial pixel-based modelling.

  6. Soil Hydrologic Response and Nutrient Movement in Three Small Tropical Catchments

    NASA Astrophysics Data System (ADS)

    Pullen, N. H.; Hamann, H. B.; Stallard, R. F.

    2004-12-01

    The movement of water over and through soils by storm-generated flowpaths in tropical forests not only mediates nutrient movement and physical weathering, but also potentially influences vegetation growth and dynamics with seasonally dry or saturated soil conditions. However, few small-scale catchment studies (10-1000ha) have produced a comprehensive, standardized dataset on soil hydrologic properties among tropical forest catchments, due in part to complexities within tropical systems, and to inconsistencies in methods, data collection, and/or analyses. In response, this study has utilized the global, standardized network of forest dynamics plots of the Center for Tropical Forest Science (CTFS) for the rapid assessment of soil saturated hydraulic conductivity (Ks) and the water chemistry from storm-generated flowpaths. Ks measurements at varying depths help in testing Elsenbeer's (2001) functional classification continuum of tropical forest soilscapes and resulting hydrologic flowpaths. In Barro Colorado Island, Panama, Ks decreased rapidly with soil depth where horizontal surface and near-surface flowpaths were most prevalent. Ks measurements in Yasuni National Park, Ecuador indicated limited vertical movement of water at depths >15cm due to an impermeable soil layer. Ks measurements from Lambir Hills National Park, Malaysia, represented both ends of the continuum due to variability in soil type and lithology. In relation to soil hydrology and hydrological flowpaths, runoff chemistry at Yasuni reveals a general pattern of increased nutrient export as water moves through the canopy and over the soil surface, with concentrations of K+ increasing significantly in throughfall, and concentrations of both K+, and NO3- remaining high in overland flow. The results from the composite overland flow samples may indicate a more open nutrient cycle in tropical forest environments than has been suggested from earlier studies using radioactively labeled isotopes.

  7. Multi-scale field investigation of water flow pathways and residence times in mountainous catchments

    NASA Astrophysics Data System (ADS)

    Lyon, S. W.; Troch, P. A.; Desilets, S. E.

    2006-12-01

    The "sky islands" of Arizona and New Mexico in the southwestern United States form a unique complex of about 27 mountain ranges whose ecosystems support many perennial and ephemeral streams in an arid climate. Among these sky islands are the Santa Catalina Mountains near Tucson, AZ, with a peak elevation of 9157 ft at Mt. Lemmon. Sabino Canyon Creek is the main stream which runs on the south face of the mountain range. It usually flows from July through April with an average daily flow of approximately 0.28 m3/s (10 cfs). However, flash floods are common both during summer as a result of intense monsoon rains and during spring because of rapid snowmelt. During these events, flow increases rapidally, reaching peak flows up to 480 m3/s (16,000 cfs, July 2006). Characterizing water flow pathways and residence times in these complex catchments is important for improving flash flood warning systems, estimating mountain front recharge, managing forest and wild fires, and understanding ecosystem functions. In the summer of 2006, we set up an extensive hydrometrical and hydro-chemical monitoring network in Sabino Canyon Creek, comprising 40 tipping bucket rain gauges (two of which were equipped to automatically collect rainwater samples), 5 automatic surface water level stations (three of which were equipped with auto samplers), and 8 manual soil lysimeters. In addition, several rain and stream water grab samples were collected manually during intensive rain events. Water samples are analyzed for major ions and liquid water isotopic concentration (2H and 18O) in rain, soil, ground and surface water. The data allows for a detailed reconstruction of water flow pathways and residence times at 3 different catchment scales (2 km2, 8 km2, and 91 km2) during the recorded flow events, including the highest monsoon rainfall-runoff event ever recorded in these mountains.

  8. The constructed catchment Chicken Creek as Critical Zone Observatory under transition

    NASA Astrophysics Data System (ADS)

    Gerwin, Werner; Schaaf, Wolfgang; Elmer, Michael; Hinz, Christoph

    2014-05-01

    The constructed catchment Chicken Creek was established in 2005 as an experimental landscape laboratory for ecosystem research. The 6 ha area with clearly defined horizontal as well as vertical boundary conditions was left for an unrestricted primary succession. All Critical Zone elements are represented at this site, which allows the study of most processes occurring at the interface of bio-, pedo-, geo- and hydrosphere. It provides outstanding opportunities for investigating interactions and feedbacks between different evolving compartments during ecosystem development. The catchment is extensively instrumented since 2005 in order to detect transition stages of the ecosystem. Data recorded with a high spatial and temporal resolution include hydrological, geomorphological, pedological, limnological as well as biological parameters. In contrast to other Critical Zone Observatories, this site offers the unique situation of an early stage ecosystem with highly dynamic system properties. The first years of development were characterized by a fast formation of geomorphological structures due to massive erosion processes at the initially non-vegetated surface. Hydrological processes led to the establishment of a local groundwater body within 5 years. In the following years the influence of biological structures like vegetation patterns gained an increasing importance. Feedbacks between developing vegetation and e.g. hydrological features became more and more dominant. As a result, different phases of ecosystem development could be distinguished until now. This observatory offers manifold possibilities to identify and disentangle complex interactions between Critical Zone processes in situ under natural conditions. The originally low complexity of the system is growing with time facilitating the identification of influences of newly developing structures on system functions. Thus, it is possible to study effects of small-scale processes on the whole system at the

  9. Global uncertainty analysis of suspended sediment monitoring using turbidimeter in a small mountainous river catchment

    NASA Astrophysics Data System (ADS)

    Navratil, O.; Esteves, M.; Legout, C.; Gratiot, N.; Nemery, J.; Willmore, S.; Grangeon, T.

    2011-02-01

    SummaryA major challenge confronting the scientific community is to understand both patterns of and controls over spatial and temporal variability of suspended sediment dynamics in rivers, as these sediment govern nutriment export, river morphology, siltation of downstream reservoirs and degradation of water quality. High-frequency suspended sediment monitoring programs are required to meet this goal, particularly research in highly erodible mountainous catchments which supply the sediment load of the entire downstream fluvial network. However, in this context, analysis of the data and their interpretation are generally limited by many sources of uncertainty in river monitoring. This paper proposes to estimate the global uncertainty of suspended sediment monitoring using turbidimeter in a small mountainous river catchment (22 km 2; Southern French Alps). We first conducted a detailed analysis of the main uncertainty components associated with the turbidity approach, i.e. a widely used method to continuously survey the suspended sediment concentration (SSC). These uncertainty components were then propagated with Monte Carlo simulations. For individual records, SSC uncertainties are found to be on average less than 10%, but they can reach 70%. At the flood scale, the mean and the maximum SSC uncertainties are on average 20% (range, 1-30%), whereas sediment yield uncertainty is a mean 30% (range, 20-50% depending on the flood considered; discharge error, 20%). Annual specific sediment yield (SSY *) was then 360 ± 100 t km -2 year -1. Uncertainty components associated with the automatic pumping procedure, discharge measurement and turbidity fluctuation at the short time scale were found to be the greatest uncertainties. SSC and SSY uncertainties were found highly site- and time-dependent as they vary significantly with the hydro-sedimentary conditions. This study demonstrates that global uncertainty accounts for only a small part of inter-flood SSC and SSY variability

  10. Optimal Spatial Design of Capacity and Quantity of Rainwater Catchment Systems for Urban Flood Mitigation

    NASA Astrophysics Data System (ADS)

    Huang, C.; Hsu, N.

    2013-12-01

    This study imports Low-Impact Development (LID) technology of rainwater catchment systems into a Storm-Water runoff Management Model (SWMM) to design the spatial capacity and quantity of rain barrel for urban flood mitigation. This study proposes a simulation-optimization model for effectively searching the optimal design. In simulation method, we design a series of regular spatial distributions of capacity and quantity of rainwater catchment facilities, and thus the reduced flooding circumstances using a variety of design forms could be simulated by SWMM. Moreover, we further calculate the net benefit that is equal to subtract facility cost from decreasing inundation loss and the best solution of simulation method would be the initial searching solution of the optimization model. In optimizing method, first we apply the outcome of simulation method and Back-Propagation Neural Network (BPNN) for developing a water level simulation model of urban drainage system in order to replace SWMM which the operating is based on a graphical user interface and is hard to combine with optimization model and method. After that we embed the BPNN-based simulation model into the developed optimization model which the objective function is minimizing the negative net benefit. Finally, we establish a tabu search-based algorithm to optimize the planning solution. This study applies the developed method in Zhonghe Dist., Taiwan. Results showed that application of tabu search and BPNN-based simulation model into the optimization model not only can find better solutions than simulation method in 12.75%, but also can resolve the limitations of previous studies. Furthermore, the optimized spatial rain barrel design can reduce 72% of inundation loss according to historical flood events.

  11. Tritium Based Water Balance Modelling In The Weser Catchment, Germany

    NASA Astrophysics Data System (ADS)

    Koeniger, P.; Krause, W.; Leibundgut, Ch.; Reisewitz, R.

    The Institute of Hydrology of the Freiburg University (IHF) in conjunction with the German Federal Institute of Hydrology (BfG) are to integrating tritium data for a water balance model. Tritium observations in precipitation and river water covering a period of 30 years are used to establish a tritium aided water balance for a 46.300 km2 area in Germany (Weser catchment). Environmental tritium in precipitation, that was mainly introduced into the water cycle by nuclear weapon testing in the 60s, and wastewater from nuclear power plants located in the catchment area are sources of the tritium input. The model is established in combination with a software routine (TRIBIL), which was developed for semi distributed water and tritium balance calculations. A mesoscale, physically based model approach with spatial classification of sub areas is used and will consider evaporation, transpiration, soil characteristics, vegetation and different runoff components. The modelling is performed in monthly time steps. Hydrological, meteorological and land use data are available from different German authorities. An outline of the project, model structure and input data as well as first results for the tributary river systems Fulda and Werra will be presented. Including the conser- vative tracer tritium into large scale modelling is a rather new approach. Feasibilities and possibilities will be tested within this project. Balancing of solutes in catchment studies can be improved and this approach can serve as an additional validation tool for water balance models.

  12. Landscape controls on spatiotemporal discharge variability in a boreal catchment

    NASA Astrophysics Data System (ADS)

    Karlsen, R. H.; Grabs, T.; Bishop, K.; Buffam, I.; Laudon, H.; Seibert, J.

    2016-08-01

    Improving the understanding of how stream flow dynamics are influenced by landscape characteristics, such as soils, vegetation and terrain, is a central endeavor of catchment hydrology. Here we investigate how spatial variability in stream flow is related to landscape characteristics using specific discharge time series from 14 partly nested subcatchments in the Krycklan basin (0.12 - 68 km2). Multivariate principal component analyses combined with univariate analyses showed that while variability in landscape characteristics and specific discharge were strongly related, the spatial patterns varied with season and wetness conditions. During spring snowmelt and at the annual scale, specific discharge was positively related to the sum of wetland and lake area. During summer, when flows are lowest, specific discharge was negatively related to catchment tree volume, but positively related to deeper sediment deposits and catchment area. The results indicate how more densely forested areas on till soils become relatively drier during summer months, while wet areas and deeper sediment soils maintain a higher summer base flow. Annual and seasonal differences in specific discharge can therefore be explained to a large extent by expected variability in evapotranspiration fluxes and snow accumulation. These analyses provide an organizing principle for how specific discharge varies spatially across the boreal landscape, and how this variation is manifested for different wetness conditions, seasons and time scales.

  13. Inferences from catchment-scale tracer circulation experiments

    NASA Astrophysics Data System (ADS)

    Botter, G.; Milan, E.; Bertuzzo, E.; Zanardo, S.; Marani, M.; Rinaldo, A.

    2009-05-01

    SummaryIn this paper the mechanisms determining the mobilization and transport of solutes driven by rainfall through runoff pathways at catchment scales are investigated through the analysis of tracer experiments. The hydro-chemical response of a small catchment in Northern Italy has been monitored in continuous during 4 weeks by properly measuring rainfall rates, streamflows and stream flux concentrations. The chemical response has been analyzed by employing two different tracers: nitrates from diffuse agricultural sources (NO3-) and lithium from a point injection (Li +). A modelling exercise simulating the observed hydro-chemical response of the test catchment has also been carried out. Inferences from the comparative analyses prove instructive, in particular concerning the scaling of mobilization processes and the age of runoff water. Indeed, the interactions between old and new water were found to be central to understand the mechanisms driving the transfer of solutes and pollutants from soil to stream water. The modeling exercises also evidenced the noteworthy potential of the formulation of transport by residence time distributions to describe large scale solute transport processes.

  14. Catchment-scale herbicides transport: Theory and application

    NASA Astrophysics Data System (ADS)

    Bertuzzo, E.; Thomet, M.; Botter, G.; Rinaldo, A.

    2013-02-01

    This paper proposes and tests a model which couples the description of hydrologic flow and transport of herbicides at catchment scales. The model accounts for streamflow components' age to characterize short and long term fluctuations of herbicide flux concentrations in stream waters, whose peaks exceeding a toxic threshold are key to exposure risk of aquatic ecosystems. The model is based on a travel time formulation of transport embedding a source zone that describes near surface herbicide dynamics. To this aim we generalize a recently proposed scheme for the analytical derivation of travel time distributions to the case of solutes that can be partially taken up by transpiration and undergo chemical degradation. The framework developed is evaluated by comparing modeled hydrographs and atrazine chemographs with those measured in the Aabach agricultural catchment (Switzerland). The model proves reliable in defining complex transport features shaped by the interplay of long term processes, related to the persistence of solute components in soils, and short term dynamics related to storm inter-arrivals. The effects of stochasticity in rainfall patterns and application dates on concentrations and loads in runoff are assessed via Monte Carlo simulations, highlighting the crucial role played by the first rainfall event occurring after herbicide application. A probabilistic framework for critical determinants of exposure risk to aquatic communities is defined. Modeling of herbicides circulation at catchment scale thus emerges as essential tools for ecological risk assessment.

  15. Assessment of surface water resources availability using catchment modelling and the results of tracer studies in the mesoscale Migina Catchment, Rwanda

    NASA Astrophysics Data System (ADS)

    Munyaneza, O.; Mukubwa, A.; Maskey, S.; Uhlenbrook, S.; Wenninger, J.

    2014-12-01

    In the present study, we developed a catchment hydrological model which can be used to inform water resources planning and decision making for better management of the Migina Catchment (257.4 km2). The semi-distributed hydrological model HEC-HMS (Hydrologic Engineering Center - the Hydrologic Modelling System) (version 3.5) was used with its soil moisture accounting, unit hydrograph, liner reservoir (for baseflow) and Muskingum-Cunge (river routing) methods. We used rainfall data from 12 stations and streamflow data from 5 stations, which were collected as part of this study over a period of 2 years (May 2009 and June 2011). The catchment was divided into five sub-catchments. The model parameters were calibrated separately for each sub-catchment using the observed streamflow data. Calibration results obtained were found acceptable at four stations with a Nash-Sutcliffe model efficiency index (NS) of 0.65 on daily runoff at the catchment outlet. Due to the lack of sufficient and reliable data for longer periods, a model validation was not undertaken. However, we used results from tracer-based hydrograph separation from a previous study to compare our model results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow. We observed considerable disparities in the parameters (e.g. groundwater storage) and runoff components across the five sub-catchments, which provided insights into the different hydrological processes on a sub-catchment scale. We conclude that such disparities justify the need to consider catchment subdivisions if such parameters and components of the water cycle are to form the base for decision making in water resources planning in the catchment.

  16. Geomorphic coupling and sediment connectivity in an alpine catchment — Exploring sediment cascades using graph theory

    NASA Astrophysics Data System (ADS)

    Heckmann, Tobias; Schwanghart, Wolfgang

    2013-01-01

    Through their relevance for sediment budgets and the sensitivity of geomorphic systems, geomorphic coupling and (sediment) connectivity represent important topics in geomorphology. Since the introduction of the systems perspective to physical geography by Chorley and Kennedy (1971), a catchment has been perceived as consisting of landscape elements (e.g. landforms, subcatchments) that are coupled by geomorphic processes through sediment transport. In this study, we present a novel application of mathematical graph theory to explore the network structure of coarse sediment pathways in a central alpine catchment. Numerical simulation models for rockfall, debris flows, and (hillslope and channel) fluvial processes are used to establish a spatially explicit graph model of sediment sources, pathways and sinks. The raster cells of a digital elevation model form the nodes of this graph, and simulated sediment trajectories represent the corresponding edges. Model results are validated by visual comparison with the field situation and aerial photos. The interaction of sediment pathways, i.e. where the deposits of a geomorphic process form the sources of another process, forms sediment cascades, represented by paths (a succession of edges) in the graph model. We show how this graph can be used to explore upslope (contributing area) and downslope (source to sink) functional connectivity by analysing its nodes, edges and paths. The analysis of the spatial distribution, composition and frequency of sediment cascades yields information on the relative importance of geomorphic processes and their interaction (however regardless of their transport capacity). In the study area, the analysis stresses the importance of mass movements and their interaction, e.g. the linkage of large rockfall source areas to debris flows that potentially enter the channel network. Moreover, it is shown that only a small percentage of the study area is coupled to the channel network which itself is

  17. 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

  18. The topographic wetness index as a predictor for hot spots of DOC export from catchments

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Oosterwoud, Marieke; Tittel, Jörg; Selle, Benny; Fleckenstein, Jan H.

    2015-04-01

    Dissolved organic carbon (DOC) concentrations in the discharge of many catchments in Europe and North America are rising. This increase is of concern for the drinking water supply from reservoirs since high DOC concentrations cause additional costs in water treatment and potentially the formation of harmful disinfection by-products. A prerequisite for understanding this increase is the knowledge on the spatial distribution of dominant soil DOC sources within catchments and on mobilization as well as transfer processes to the surface water. A number of studies identified wetland soils as the dominant source with fast mobilization and short transit times to the receiving surface water. However, most studies have either focussed on smaller, hillslope and single catchment or on larger scale multi-catchment assessments. Moreover, information on the distribution of soil types in catchments is not always readily available. This study brings together both types of assessment in a data-driven top-down approach: (i) a detailed survey on DOC concentration and loads over the course of one year within two paired data-rich catchments discharging into a large drinking water reservoir in central Germany and (ii) a database of hydrochemistry and physio-geographic characteristics of 113 catchments draining into 58 reservoirs across Germany over the course of 16 years. The objective is to define hot spots of DOC export within the catchments for both types of assessments (i, ii) and to test the suitability of the topographic wetness index (TWI) as a proxy for well-connected wetland soils at various spatial scales. In the sub-catchments of assessment (i) the spatial variability of concentrations and loads was much smaller than expected. None of the studied sub-catchments was a predominant producer of the total DOC loads exported from the catchments. We found the mean concentrations and loads to be positively correlated with the share of groundwater-dominated soils in the sub-catchments

  19. Sediment transfer in coastal catchments exposed to typhoons: lessons learnt from catchments contaminated with Fukushima radioactive fallout

    NASA Astrophysics Data System (ADS)

    Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Lefèvre, Irène

    2016-04-01

    Several coastal catchments located in Northeastern Japan received significant radioactive fallout following the Fukushima nuclear accident in March 2011, with initial 137Cs activities exceeding 100 kBq m-2. Although radiocesium poses a considerable health risk for local populations, it also provides a relatively straightforward tracer to investigate sediment transfers in catchments exposed to spring floods and heavy typhoons in late summer and early fall. This study focused on two catchments (the Niida and Mano Rivers) covering a surface area of 450 km² that drain the main radioactive plume. A database of radiocesium activities measured in potential source samples (n=260) was used to model radiocesium dilution in 342 sediment deposit samples collected at 38 locations during 9 different sampling campaigns conducted every 6 months from Nov. 2011 to Nov. 2015. The dilution of the initial radiocesium contamination in sediment was individually calculated for each of the 342 samples using a distribution model. Results show that the proportion of heavily contaminated sediment increased from 27% to 39% after the occurrence of typhoons in 2013 (with rainfall amount exceeding 100 mm in 48 hours) and from 29% to 45% after the 2015 spring floods, illustrating the occurrence of soil erosion and resuspension of contaminated material stored in the river channel. In contrast, the occurrence of a very strong typhoon in September 2015 (up to 450 mm in 48h) led to the dilution and the flush of the contamination to the Pacific Ocean, with the proportion of heavily contaminated material decreasing from 45 to 21%. This case study in catchments impacted by the Fukushima accident illustrates their high reactivity to both human activities and rainfall. These results will improve our understanding of sediment transfers in similar coastal mountainous environments frequently exposed to heavy rainfall.

  20. High resolution modeling of a small urban catchment

    NASA Astrophysics Data System (ADS)

    Skouri-Plakali, Ilektra; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    Flooding is one of the most complex issues that urban environments have to deal with. In France, flooding remains the first natural risk with 72% of decrees state of natural disaster issued between October 1982 and mid-November 2014. Flooding is a result of meteorological extremes that are usually aggravated by the hydrological behavior of urban catchments and human factors. The continuing urbanization process is indeed changing the whole urban water cycle by limiting the infiltration and promoting runoff. Urban environments are very complex systems due to their extreme variability, the interference between human activities and natural processes but also the effect of the ongoing urbanization process that changes the landscape and hardly influences their hydrologic behavior. Moreover, many recent works highlight the need to simulate all urban water processes at their specific temporal and spatial scales. However, considering urban catchments heterogeneity still challenging for urban hydrology, even after advances noticed in term of high-resolution data collection and computational resources. This issue is more to be related to the architecture of urban models being used and how far these models are ready to take into account the extreme variability of urban catchments. In this work, high spatio-temporal resolution modeling is performed for a small and well-equipped urban catchment. The aim of this work is to identify urban modeling needs in terms of spatial and temporal resolution especially for a very small urban area (3.7 ha urban catchment located in the Perreux-sur-Marne city at the southeast of Paris) MultiHydro model was selected to carry out this work, it is a physical based and fully distributed model that interacts four existing modules each of them representing a portion of the water cycle in urban environments. MultiHydro was implemented at 10m, 5m and 2m resolution. Simulations were performed at different spatio-temporal resolutions and analyzed with

  1. Storm-driven pesticide dynamics in a catchment system

    NASA Astrophysics Data System (ADS)

    Harrison, Rebecca; Freer, Jim; Michaelides, Katerina; Hurley, Steven; Howden, Nicholas; Bull, Ian

    2013-04-01

    Loss of pesticides from agricultural land in runoff and subsurface flow during rainfall events poses a significant concern for water quality, with adverse effects on drinking water and aquatic life. Pesticide mobilisation and transport is affected by runoff and erosion processes which leads to different flow pathways and pesticide residence times in a catchment. In the soil and sediment environment pesticides can be a significant component of surface water contamination because of their persistence in soil and sediment and that they have a tendency to desorb back into water over time. A lowland agricultural catchment upstream of a drinking-water supply reservoir in the South West of England is being used to investigate pesticide dynamics at the catchment scale during individual storm events. Pesticide concentration in water and suspended sediments were determined from samples taken at incremental changes in stream flow incorporating both rising and falling river levels. The study aims to determine the relative partitioning of pesticides transported in the dissolved phase or adsorbed to sediment. Analyses of soil, sediment and water from across the catchment aids understanding of the interaction between different media and can be used to determine the importance of dissolved and sediment-bound pesticide dynamics during individual storm events. Initial results imply that processes of transport and desorption are occurring in both soils and river and reservoir sediments which are likely to be an important factor for timing of pesticide movement. This suggests soil and sediment are acting as a sustained source of contamination to surface water. However; interactions between these different media are complex. Investigation of the molluscicide metaldehyde, showed this to be present in stream water at concentrations greater than 0.1 µg µl-1 nine months after application. Storm event analysis shows peak pesticide concentration in the stream to coincide with storm

  2. 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

  3. Curve numbers for olive orchard catchments in Spain

    NASA Astrophysics Data System (ADS)

    Taguas, Encarnación; Yuan, Yongping; Licciardello, Feliciana; Gómez, Jose

    2014-05-01

    The Curve Number (CN) method (Soil Conservation Service, 1972) is widely applied around the world to estimate direct runoff and the corresponding hydrograph of a rainfall event. Its efficient and simple computation, its complete parameterization for different soils, uses and managements and its good performance justify its application. Nevertheless, apart from Romero et al. (2007) who calculated CN-values at the plot scale, there is little information on the model performance in olive orchards at the catchment scale. In this work, the CN-model has been applied in three small catchments in Spain ranging between 6 and 8 ha with different soil types (regosol, luvisol and vertisol), topography (mean slopes between 9-15%) and management practices (non-tillage with a spontaneous grass cover, minimum tillage, conventional tillage). A rainfall-runoff dataset of 6 years have been used to test the usefulness of model as well as the accuracy of its reference parameterization (CNs and of initial substraction, Ia). CN-values were adjusted, optimized and compared with reference values for orchard crops while the sensitivity of the goodness of fit to Ia was described for each catchment. Classical equations based on the use of CN-percentiles 50, 10 and 90 for determining the antecedent moisture content (AMC) provided very good results with Nash-Sutcliffe coefficients of efficiency equal to 0.73 and 0.81 in two of the catchments with an annual rainfall higher than 600 mm. The third one -with an annual rainfall lower than 400 mm and spontaneous grass cover- showed a different pattern where a multiple linear regression dependant on precipitation and temperature features, represented notably better the rainfall-runoff relationships. Although fractions of Ia on the storage (S) equal to 0.15 and 0.25 allowed to optimize the adjustments of CN, the usual reference of 0.20 is quite appropriate. Finally, significant deviations were observed on reference-CNs for sandy soils that should be

  4. Salinity and the discharge of salts from catchments in Australia

    NASA Astrophysics Data System (ADS)

    Peck, A. J.; Hatton, Tom

    2003-03-01

    Discharge of soluble salts from catchments following clearing of native vegetation for dryland agriculture is a serious environmental and economic problem affecting soil and water resources in Australia. The fundamental challenges are: To identify areas of soil at risk of becoming saline. To relate soil and water salinity risk to options for management of land in the area that contributes to the risk, and thereby contribute to the evaluation of management options. These challenges are faced in an environment where native vegetation has roots that extend to depths of order 10 m in soil profiles that are formed by in situ weathering of granitic rocks and dolerite dykes to depths of about 20 m. The profiles typically contain 1-100 kg m -2 of salt (primarily sodium chloride) in solution in the pore water. The distribution of soluble salts, and the movement of water within most of the unsaturated zone of these soils results from a combination of matrix flow and flow through remnant root channels and larger-scale structures with geologic origins. Recognized options for management of salinity risk, or to reduce existing areas of saline soil, are revegetation of part of the cleared land with alternative species, pumping to lower the watertable in selected areas, and construction of ditch drains for control of surface water and shallow groundwater. All options are constrained by the economics of dryland farming, and pumping or drainage is further constrained by possible environmental impacts of disposal of saline water. Application of soil physics/hydrology to salinity in Australia has contributed to understanding, but generally it has proven to be inadequate to aid the development of effective management strategies. A classic approach to soil water movement at the primary catchment scale (areas of order 10 6 m 2 or more) will always be limited by errors of measurement at each site within the catchment, those arising from the method of estimation of soil characteristics

  5. 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

  6. Decadal and seasonal trends of nutrient concentration and export from highly managed coastal catchments.

    PubMed

    Wan, Yongshan; Wan, Lei; Li, Yuncong; Doering, Peter

    2017-03-02

    Understanding anthropogenic and hydro-climatic influences on nutrient concentrations and export from highly managed catchments often necessitates trend detection using long-term monitoring data. This study analyzed the temporal trend (1979-2014) of total nitrogen (TN) and total phosphorus (TP) concentrations and export from four adjacent coastal basins in south Florida where land and water resources are highly managed through an intricate canal network. The method of integrated seasonal-trend decomposition using LOESS (LOcally weighted regrESSion) was employed for trend detection. The results indicated that long-term trends in TN and TP concentrations (increasing/decreasing) varied with basins and nutrient species, reflecting the influence of basin specific land and water management practices. These long-term trends were intervened by short-term highs driven by high rainfall and discharges and lows associated with regional droughts. Seasonal variations in TP were more apparent than for TN. Nutrient export exhibited a chemostatic behavior for TN from all the basins, largely due to the biogenic nature of organic N associated with the ubiquity of organic materials in the managed canal network. Varying degrees of chemodynamic export was present for TP, reflecting complex biogeochemical responses to the legacy of long-term fertilization, low soil P holding capacity, and intensive stormwater management. The anthropogenic and hydro-climatic influences on nutrient concentration and export behavior had great implications in nutrient loading abatement strategies for aquatic ecosystem restoration of the downstream receiving waterbody.

  7. Old groundwater influence on stream hydrochemistry and catchment response times in a small Sierra Nevada catchment: Sagehen Creek, California

    USGS Publications Warehouse

    Rademacher, L.K.; Clark, J.F.; Clow, D.W.; Hudson, G.B.

    2005-01-01

    [1] The relationship between the chemical and isotopic composition of groundwater and residence times was used to understand the temporal variability in stream hydrochemistry in Sagehen basin, California. On the basis of the relationship between groundwater age and [Ca2+], the mean residence time of groundwater feeding Sagehen Creek during base flow is approximately 28 years. [Cl-]:[Ca2+] ratios in Sagehen Creek can be used to distinguish between two important processes: changes in the apparent age of groundwater discharging into the creek and dilution with snowmelt. The mean residence time of groundwater discharging into the creek is approximately 15 years during snowmelt periods. The results from this study have implications for hydrograph separation studies as groundwater is not a single, well-mixed chemical component but rather is a variable parameter that predictably depends on groundwater residence time. Most current models of catchment hydrochemistry do not account for chemical and isotopic variability found within the groundwater reservoir. In addition, this study provides valuable insight into the long-term hydrochemical response of a catchment to perturbations as catchment-flushing times are related to the mean residence time of water in a basin. Copyright 2005 by the American Geophysical Union.

  8. Digital catchment observatories: A platform for engagement and knowledge exchange between catchment scientists, policy makers, and local communities

    NASA Astrophysics Data System (ADS)

    Mackay, E. B.; Wilkinson, M. E.; Macleod, C. J. A.; Beven, K.; Percy, B. J.; Macklin, M. G.; Quinn, P. F.; Stutter, M.; Haygarth, P. M.

    2015-06-01

    Increasing pressures on the hydrological cycle from our changing planet have led to calls for a refocus of research in the sciences of hydrology and water resources. Opportunities for new and innovative research into these areas are being facilitated by advances in the use of cyberinfrastructure, such as the development of digital catchment observatories. This is enabling research into hydrological issues such as flooding to be approached differently. The ability to combine different sources of data, knowledge, and modeling capabilities from different groups such as scientists, policy makers, and the general public has the potential to provide novel insights into the way individual catchments respond at different temporal and spatial scales. While the potential benefits of the digital catchment observatory are large, this new way of carrying out research into hydrological sciences is likely to prove challenging on many levels. Along with the obvious technical and infrastructural challenges to this work, an important area for consideration is how to enable a digital observatory to work for a range of potential end-users, paving the way for new areas of research through developing a platform effective for engagement and knowledge exchange. Using examples from the recent local-scale hydrological exemplar in the Environmental Virtual Observatory pilot project (http://www.evo-uk.org), this commentary considers a number of issues around the communication between and engagement of different users, the use of local knowledge and uncertainty with cloud-based models, and the potential for decision support and directions for future research.

  9. Fluvial network imprints on microbial diversity and community network topology

    NASA Astrophysics Data System (ADS)

    Battin, T. J.; Besemer, K.; Widder, S.; Singer, G. A.; Ceola, S.; Bertuzzo, E.; Quince, C.; Sloan, W. T.; Rinaldo, A.

    2013-12-01

    Streams and rivers sculpt continental landscapes and the networks they form carry universal signatures of spatial organization. Biodiversity in fluvial networks ranks among the highest on Earth and microorganisms therein, often enclosed in biofilms, fulfill critical ecosystem functions even with repercussions on the global carbon cycle. We extensively used 454 pyrosequencing on biofilm samples from more than 100 streams from a 5th-order catchment, derived alpha and beta diversity patterns and, using co-occurrence analyses, we studied community network organization. Contrary to current theory and to animal diversity studies, we found microbial alpha diversity in biofilms to decrease downstream with confluences likely acting as filters to biodiversity as it propagates from the smallest headwaters to larger rivers. Along with higher beta diversity in the headwaters, these findings highlight headwaters as critical reservoirs of microbial diversity for entire fluvial networks. Co-occurrence analyses revealed a lower level of fragmentation of community networks in headwaters than in larger rivers downstream and further identified gatekeepers (at family level) as potential architects of the observed network topology. Similarly, fragmentation was higher downstream than upstream of confluences. Consistent with current network theory, simple model simulations suggest that fragmentation patterns are linked to persistence against perturbations. We further explore the role of perturbation for community network topology in the context of fluvial network hydrology. Our findings have deep implications for restoration and conservation. They portrait the imprint of fluvial networks on microbial community networks and thereby expand our knowledge on biodiversity and ecosystem persistence.

  10. The "Teflon basin" myth: Snow-soil interactions in mountain catchments in the western US

    NASA Astrophysics Data System (ADS)

    Williams, M. W.; Cowie, R. M.

    2015-12-01

    In much of western North America, snow and snowmelt provide the primary means for storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. A common assumption is that high-elevation catchments in the western United States behave like "Teflon basins" and that water released from seasonal storage in snow packs flows directly into streams with little or no interaction with underlying soils. Here I present information from a variety of catchments in the Colorado Front Range on snowmelt/soil interactions using isotopic, geochemical, nutrient and hydrometric data in 2- and 3- component hydrograph separations, along with end-member mixing analysis (EMMA). For most catchments we measured these parameters in weekly precipitation, the seasonal snowpack, snowmelt before contact with the ground, discharge, springs, soil solution, and groundwater. We ran EMMA at the catchment scale for catchments that represent the rain-snow transition zone in the montane forest, the seasonally snow covered sub-alpine to alpine transition zone, and a high-elevation alpine zone near the continental divide. In all catchments three end-members were the source waters for about 95% of discharge. Two end-members were the same in all catchments, snow and groundwater. For the alpine catchment talus springs was the third water source, while rain was the third water source in the two lower-elevation catchments. For all three catchments, soil solution plotted with stream waters along or near a line connecting the snow and groundwater end-members. Thus, for seasonally snow-covered catchments from montane to alpine ecosystems, snowmelt infiltrates underlying soils before snowmelt recharges groundwater reservoirs and contributes to surface flows. Seasonally snow-covered catchments are not Teflon basins. Rather, snowmelt infiltrates soils where solute concentrations are changed by biological and geochemical processes.

  11. Sediment transport in steep forested catchments - An assessment of scale and disturbance

    NASA Astrophysics Data System (ADS)

    Hancock, G. R.; Hugo, J.; Webb, A. A.; Turner, L.

    2017-04-01

    Stream sediment loads (both bedload and suspended sediment) are problematic to measure due to the time and equipment needed. There is a dearth of such data sets globally let alone for Australia. However, such data are needed to quantify sediment transport type and rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. Here we present the findings from 8 steepslope forested catchments dominated by headwater streams (size range 15-100 ha) in south-eastern Australia where both bedload and suspended load have been measured over multiple years. The results demonstrate that suspended load is the dominant component and there is no consistent suspended to bedload ratio for the catchments. The suspended sediment to bedload ratio appears to be catchment specific. There was no relationship between total load (or bedload/suspended load) and average catchment slope, stream length, shape or any geomorphic descriptor. However catchment total load was found to be significantly related to catchment area. Of the 8 catchments examined here, 6 had been harvested for timber in previous decades (with large areas of forest removed) while 2 catchments had minimal disturbance (Control catchments). There was no difference in sediment loads from the harvested and Control catchments. The results demonstrate that although land disturbance had previously occurred the management practices employed in each catchment were effective in the long term. This provides confidence that the forest harvesting and subsequent management do not produce detrimental effects in the medium to long term. An assessment of erosion rates and likely soil production rates suggests that the catchments are eroding soil at the rate it is being produced.

  12. Multiple-method approaches for quantifying fine sediment dynamics in river catchments over contemporary timescales

    NASA Astrophysics Data System (ADS)

    Smith, Hugh

    2015-04-01

    Understanding the patterns and processes of contemporary fine sediment dynamics in river catchments constitutes a key research challenge for catchment scientists. Such knowledge has considerable value for the targeting of management resources to reduce excess fine sediment supply and its impacts on water resources and aquatic ecosystems. Many past studies tended to focus on a single compartment of the fine sediment cascade and utilised a limited range of research methods. For more holistic understanding, the use of multiple-method approaches is required to provide data on the sources, transfer, storage, and transit times of fine sediment in river catchments. Such approaches would allow scientists to better conceptualise catchment processes controlling the movement of fine sediment across a range of spatial scales. It may also enhance the scientific quality of catchment-scale studies through the acquisition of multiple lines of evidence concerning a particular research problem. The specific combination of fine sediment tracing and fingerprinting procedures with catchment sediment flux measurements and sediment budget modelling has considerable potential to enhance our knowledge of contemporary sediment dynamics. This combination of techniques offers complementary information and the opportunity to compare datasets, such as estimates of catchment sediment source contributions obtained using sediment tracers with direct measurements of sediment fluxes or catchment model outputs. This contribution explores the potential for such combinations of methods to yield distinctive insights not otherwise available from the use of only one of these techniques. It draws on published examples of multiple-method studies by the author from small agricultural and wildfire-affected forest catchments (1-2 km2) in south-east Australia and from larger agricultural river catchments (38-920 km2) in south-west England. It will also identify possible directions for catchment research based

  13. Progress in the identification of catchments with co-existent multiple steady states and finite resilience

    NASA Astrophysics Data System (ADS)

    Peterson, T. J.; Western, A. W.; Thyer, M. A.; Frost, A. J.

    2015-12-01

    Hydrology has implicitly assumed that catchments are infinitely resilient to droughts and floods. No matter the magnitude of the climatic disturbance, almost all hydrological models simulate full recovery and hence assume infinite resilience. Recent research shows that catchments can undergo fundamental change during major droughts and this change in behavior is not captured by rainfall-runoff models. To date, the field of hydrological resilience has relied on theoretical deterministic models or vague resilience concepts, with the identification of catchments with multiple steady states (henceforth, attractors) remaining elusive. This is primarily due to the challenges stochastic forcing introduces into quantifying disturbance and recovery, and because resilience theory does not adequately address stochastic forcing. Drawing from recent hydrological resilience theory on catchment disturbance and recovery, a data-driven hidden Markov model is proposed for identifying recovery to a different hydrological state following major climatic disturbances. Application to selected unregulated catchments within Victoria, Australia, shows that after the Millennium Drought (~1995-2010) some catchments are yet to recover and have persisted within a functionally different hydrological state compared to that prior to the drought. Conversely, some catchments fully recovered at the cessation of the drought. This provides the first known field evidence that some catchments may have multiple attractors. Additionally, catchments are shown to differ in their resistance to the drought, with some catchments switching to a drought state at the commencement of the meteorological drought while other catchments taking ~10 years to switch to a hydrological drought state. In addition to separating hydrological droughts from meteorological droughts, this research provides a pathway for quantifying catchment resilience and resistance to climatic disturbances.

  14. Factors controlling inter-catchment variation of mean transit time with consideration of temporal variability

    NASA Astrophysics Data System (ADS)

    Ma, Wenchao; Yamanaka, Tsutomu

    2016-03-01

    The catchment transit time, a lumped descriptor reflecting both time scale and spatial structure of catchment hydrology can provide useful insights into chemical/nuclear pollution risks within a catchment. Despite its importance, factors controlling spatial variation of mean transit time (MTT) are not yet well understood. In this study, we estimated time-variant MTTs for about ten years (2003-2012) in five mesoscale sub-catchments of the Fuji River catchment, central Japan, to establish the factors controlling their inter-catchment variation with consideration of temporal variability. For this purpose, we employed a lumped hydrological model that was calibrated and validated by hydrometric and isotopic tracer observations. Temporal variation patterns of estimated MTT were similar in all sub-catchments, but with differing amplitudes. Inter-catchment variation of MTT was greater in dry periods than wet periods, suggesting spatial variation of MTT is controlled by water 'stock' rather than by 'flow'. Although the long-term average MTT (LAMTT) in each catchment was correlated with mean slope, coverage of forest (or conversely, other land use types), coverage of sand-shale conglomerate, and groundwater storage, the multiple linear regression revealed that inter-catchment variation of LAMTT is principally controlled by the amount of groundwater storage. This is smaller in mountainous areas covered mostly by forests and greater in plain areas with less forest coverage and smaller slope. This study highlights the topographic control of MTT via groundwater storage, which might be a more important factor in mesoscale catchments, including both mountains and plains, rather than in smaller catchments dominated by mountainous topography.

  15. Detecting non-stationary hydrologic model parameters in a paired catchment system using data assimilation

    NASA Astrophysics Data System (ADS)

    Pathiraja, S.; Marshall, L.; Sharma, A.; Moradkhani, H.

    2016-08-01

    Non-stationarity represents one of the major challenges facing hydrologists. There exists a need to develop modelling systems that are capable of accounting for potential catchment changes, in order to provide useful predictions for the future. Such changes may be due to climatic temporal variations or human induced changes to land cover. Extensive research has been undertaken on the impacts of land-use change on hydrologic behaviour, however, few studies have examined this issue in a predictive modelling context. In this paper, we investigate whether a time varying model parameter estimation framework that uses the principles of Data Assimilation can improve prediction for two pairs of experimental catchments in Western Australia. All catchments were initially forested, but after three years one catchment was fully cleared whilst another had only 50% of its area cleared. Their adjacent catchments remained unchanged as a control. Temporal variations in parameters were detected for both treated catchments, with no comparable variations for the control catchments. Improved streamflow prediction and representation of soil moisture dynamics were also seen for the time varying parameter case, compared to when a time invariant parameter set from the calibration period was used. While we use the above mentioned catchments to illustrate the usefulness of the approach, the methods are generic and equally applicable in other settings. This study serves as an important validation step to demonstrate the potential for time varying model structures to improve both predictions and modelling of changing catchments.

  16. Understanding catchment classification and similarity through correlation in streamflow time series

    NASA Astrophysics Data System (ADS)

    Fleming, Brandon; Archfield, Stacey

    2013-04-01

    Catchment classification is an important component of hydrologic analyses, particularly for linking changes in ecological integrity to streamflow alteration, transferring time series or model parameters from gauged to ungauged locations, and as a way to understand the similarity in the response of catchments to change. Metrics of similarity used in catchment classification have ranged from aggregate catchment properties such as geologic or climate characteristics to variables derived from the daily streamflow hydrograph; however, no one set of classification variables can fully describe similarity between catchments as the variables used for such assessments often depend on the question being asked. We propose an alternative method based on similarity for hydrologic classification: correlation between the daily streamflow time series. If one assumes that the streamflow signal is the integrated response of a catchment to both climate and geology, then the strength of correlation in streamflow between two catchments is a measure of the strength of similarity in hydrologic response between those two catchments. Using the nonparametric Spearman rho correlation coefficient between streamflow time series at 54 unregulated and unaltered streamgauges in the mid-Atlantic United States, we show that correlation is a parsimonious classification metric that results in physically interpretable classes. Using the correlation between the deseasonalized streamflow time series and reclassifying the streamgauges, we also find that seasonality plays an important role in understanding catchment flow dynamics, especially those that can be linked to ecological response and similarity although not to a large extent in this study area.

  17. Evidence for a Flushing Mechanism of Nitrate Export from Susannah Brook Catchment

    NASA Astrophysics Data System (ADS)

    Ocampo, C. J.; Sivapalan, M.; Turner, J. V.; Oldham, C.

    2001-12-01

    The mechanism of nitrate export from catchments can be addressed by the identification of flow paths along which water is routed and the different time scales at which hydrologic and biogeochemical processes occur. This mechanism was investigated in Susannah Brook catchment (SB), a 24 square kilometre area rural catchment near Perth, Western Australia (Australia), which experiences high nitrate-nitrogen export to the Swan-Canning Rivers and Estuaries. Storm event isotopic (deuterium) and chemical (chloride) data were used to obtain the time source components of stormflow hydrographs and to relate them to nitrate export from the catchment. Storm, seasonal, and inter-annual variation of those components were investigated using standard isotopic and chemical hydrograph separation techniques, performed over 50 storm events recorded in three different hydrological catchment conditions: mean, wet, and dry years. Results from the hydrograph separation indicate the dominance of a pre-event water source in the catchment. The dynamics of contributing areas for saturated overland flow estimated from the event component was found to be consistent with hydrometric data and nitrate discharges from the catchment. There is evidence of a flushing mechanism of nitrate discharges operating within the catchment controlled by the dynamics of a shallow ephemeral perched aquifer built up during the raining season. Results suggest the viability in using hydrologic state variables in our approaches linking hydrologic and biogeochemical processes at catchment scale.

  18. 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.

  19. Comparative analysis of threshold rainfall-runoff response of small catchments in North Carolina's Piedmont region

    NASA Astrophysics Data System (ADS)

    James, A. L.; Kuntukova, K.; Fu, C.; Dreps, C.; Sun, G.

    2011-12-01

    Recent catchment hydrologic studies have focused on examination of a threshold rainfall-runoff response of hillslopes and small catchments. This threshold response, where runoff generated by a catchment shows a strong nonlinear change as a function of a combined metric of antecedent storage and storm size is of particular interest as it has been proposed as a common or shared behavior. In this study, we analyzed rainfall-runoff data and a series of antecedent storage metrics from five catchments (10-30 ha in size) in North Carolina's Piedmont region for evidence of threshold response. Although located within five miles of each other, the five catchments represent two groupings of catchments with strongly contrasting terrain characteristics, defined here by differences in soils, topography and drainage density. Despite these differences, results showed that each catchment exhibits a clear threshold rainfall-runoff response. Using these experimental results, we have begun to examine whether distributed hydrologic models can capture this shared behavior across sites. The threshold response quantified here and by similar studies offers an interesting summary of catchment response under changing combinations of storm size and antecedent moisture conditions, both variables possibly affected by climate change. In the case of the Triangle area of the Piedmont region of North Carolina, a region that is undergoing increasingly rapid urbanization, these catchments also represent landscape critical to the long term sustainable development of the Falls Lake reservoir, the drinking water source for over half a million people.

  20. Effect of catchment characteristics on aquatic carbon export from a boreal catchment and its importance in regional carbon cycling.

    PubMed

    Huotari, Jussi; Nykänen, Hannu; Forsius, Martin; Arvola, Lauri

    2013-12-01

    Inland waters transport and emit into the atmosphere large amounts of carbon (C), which originates from terrestrial ecosystems. The effect of land cover and land-use practises on C export from terrestrial ecosystems to inland waters is not fully understood, especially in heterogeneous landscapes under human influence. We sampled for dissolved C species in five tributaries with well-determined subcatchments (total size 174.5 km(2)), as well as in various points of two of the subcatchments draining to a boreal lake in southern Finland over a full year. Our aim was to find out how land cover and land-use affect C export from the catchments, as well as CH4 and CO2 concentrations of the streams, and if the origin of C in stream water can be determined from proxies for quality of dissolved organic matter (DOM). We further estimated the gas evasion from stream surfaces and the role of aquatic fluxes in regional C cycling. The export rate of C from the terrestrial system through an aquatic conduit was 19.3 g C m(-2) (catchment) yr(-1), which corresponds to 19% of the estimated terrestrial net ecosystem exchange of the catchment. Most of the C load to the recipient lake consisted of dissolved organic carbon (DOC, 6.1 ± 1.0 g C m(-2) yr(-1)); the share of dissolved inorganic carbon (DIC) was much smaller (1.0 ± 0.2 g C m(-2) yr(-1)). CO2 and CH4 emissions from stream and ditch surfaces were 7.0 ± 2.4 g C m(-2) yr(-1) and 0.1 ± 0.04 g C m(-2) yr(-1), respectively, C emissions being thus equal with C load to the lake. The proportion of peatland in the catchment and the drainage density of peatland increased DOC in streams, whereas the proportion of agricultural land in the catchment decreased it. The opposite was true for DIC. Drained peatlands were an important CH4 source for streams.

  1. Developing a Framework to Link Catchment Modelling tools to Decision Support Systems for Catchment Management and Planning

    NASA Astrophysics Data System (ADS)

    Adams, Russell; Owen, Gareth

    2015-04-01

    Over the past few years a series of catchment monitoring studies in the UK have developed a wide range of tools to enable managers and planners to make informed decisions to target several key outcomes. These outcomes include the mitigation of diffuse pollution and the reduction of flood risk. Good progress has been but additional steps are still required to link together more detailed models that represent catchment processes with the decision support systems (often termed matrices; i.e. DSMs) which form the basis of these planning and management tools. Examples include: (i) the FARM tools developed by the PROACTIVE team at Newcastle University to assess different catchment management options for mitigating against flooding events, (ii) TOPMANAGE, a suite of algorithms that link with high resolution DEMs to enable surface flow pathways, having the potential to be mitigated by Natural Flood Management (NFM) features (in order to target diffuse pollution due to nutrients and sediments) to be identified. To date, these DSMs have not been underpinned by models that can be run in real-time to quantify the benefits in terms of measurable reductions in flood or nutrient pollution risks. Their use has therefore been mostly as qualitative assessment tools. This study aims to adapt an existing spreadsheet-based model, the CRAFT, in order for it to become fully coupled to a DSM approach. Previous catchment scale applications of the CRAFT have focussed on meso-scale studies where any management interventions at a local scale are unlikely to be detectable at the monitoring point (the catchment outlet). The model has however been reasonably successful in identifying potential flow and transport pathways that link the headwater subcatchments to the outlet. Furthermore, recent enhancements to the model enable features such as sedimentation ponds and lagoons that can trap and remove nutrients and sediments to be added, once data become available from different types of NFM

  2. An approach for aggregating upstream catchment information to support research and management of fluvial systems across large landscapes.

    PubMed

    Tsang, Yin-Phan; Wieferich, Daniel; Fung, Kuolin; Infante, Dana M; Cooper, Arthur R

    2014-01-01

    The growing quality and availability of spatial map layers (e.g., climate, geology, and land use) allow stream studies, which historically have occurred over small areas like a single watershed or stream reach, to increasingly explore questions from a landscape perspective. This large-scale perspective for fluvial studies depends on the ability to characterize influences on streams resulting from throughout entire upstream networks or catchments. While acquiring upstream information for a single reach is relatively straight-forward, this process becomes demanding when attempting to obtain summaries for all streams throughout a stream network and across large basins. Additionally, the complex nature of stream networks, including braided streams, adds to the challenge of accurately generating upstream summaries. This paper outlines an approach to solve these challenges by building a database and applying an algorithm to gather upstream landscape information for digitized stream networks. This approach avoids the need to directly use spatial data files in computation, and efficiently and accurately acquires various types of upstream summaries of landscape information across large regions using tabular processing. In particular, this approach is not limited to the use of any specific database software or programming language, and its flexibility allows it to be adapted to any digitized stream network as long as it meets a few minimum requirements. This efficient approach facilitates the growing demand of acquiring upstream summaries at large geographic scales and helps to support the use of landscape information in assisting management and decision-making across large regions.

  3. Data mining of external and internal forcing of fluvial systems for catchment management: A case study on the Red River (Song Hong), Vietnam

    NASA Astrophysics Data System (ADS)

    Schmitt, Rafael; Bizzi, Simone; Castelletti, Andrea

    2013-04-01

    The understanding of river hydromorphological processes has been recognized in the last decades as a priority of modern catchment management, since interactions of natural and anthropogenic forces within the catchment drives fluvial geomorphic processes, which shape physical habitat, affect river infrastructures and influence freshwater ecological processes. The characterization of river hydromorphological features is commonly location and time specific and highly resource demanding. Therefore, its routine application at regional or national scales and the assessment of spatio-temporal changes as reaction to internal and external disturbances is rarely feasible at present. Information ranging from recently available high-resolution remote-sensing data (such as DEM), historic data such as land use maps or aerial photographs and monitoring networks of flow and rainfall, open up novel and promising capacity for basin-wide understanding of dominant hydromorphological drivers. Analysing the resulting multiparametric data sets in their temporal and spatial dimensions requires sophisticated data mining tools to exploit the potential of this information. We propose a novel framework that allows for the quantitative assessment of multiparametric data sets to identify classes of channel reaches characterized by similar geomorphic drivers using remote-sensing data and monitoring networks available in the catchment. This generic framework was applied to the Red River (Song Hong) basin, the second largest basin (87,800 sq.km) in Vietnam. Besides its economic importance, the river is experiencing severe river bed incisions due to recent construction of new dams in the upstream part of the catchment and sand mining in the surrounding of the capital city Hanoi. In this context, characterized by an high development rate, current efforts to increase water productivity and minimize impacts on the fluvial systems by means of focused infrastructure and management measures require a

  4. Assessment of surface water resources availability using catchment modeling and the results of tracer studies in the meso-scale Migina Catchment, Rwanda

    NASA Astrophysics Data System (ADS)

    Munyaneza, O.; Mukubwa, A.; Maskey, S.; Wenninger, J.; Uhlenbrook, S.

    2013-12-01

    In the last couple of years, different hydrological research projects were undertaken in the Migina catchment (243.2 km2), a tributary of the Kagera river in Southern Rwanda. These projects were aimed to understand hydrological processes of the catchment using analytical and experimental approaches and to build a pilot case whose experience can be extended to other catchments in Rwanda. In the present study, we developed a hydrological model of the catchment, which can be used to inform water resources planning and decision making. The semi-distributed hydrological model HEC-HMS (version 3.5) was used with its soil moisture accounting, unit hydrograph, liner reservoir (for base flow) and Muskingum-Cunge (river routing) methods. We used rainfall data from 12 stations and streamflow data from 5 stations, which were collected as part of this study over a period of two years (May 2009 and June 2011). The catchment was divided into five sub-catchments each represented by one of the five observed streamflow gauges. The model parameters were calibrated separately for each sub-catchment using the observed streamflow data. Calibration results obtained were found acceptable at four stations with a Nash-Sutcliffe Model Efficiency of 0.65 on daily runoff at the catchment outlet. Due to the lack of sufficient and reliable data for longer periods, a model validation (split sample test) was not undertaken. However, we used results from tracer based hydrograph separation from a previous study to compare our model results in terms of the runoff components. It was shown that the model performed well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and base flow. We observed considerable disparities in the parameters (e.g. groundwater storage) and runoff components across the five sub-catchments, that provided insights into the different hydrological processes at sub-catchment scale. We conclude that such disparities justify the need

  5. Quantifying the contribution of land use and climate change to stream flow alteration in tropical catchments

    NASA Astrophysics Data System (ADS)

    Marhaento, Hero; Booij, Martijn J.; Hoekstra, Arjen Y.

    2015-04-01

    A new approach is introduced to measure the quantitative contribution of land use and climate change to stream flow alteration based on the changes in the proportion of excess water relative to changes in the proportion of excess energy. The quantitative contribution is estimated based on three measures: (1) the resultant length (R) which indicates the magnitude of the changes in the proportion of excess water and energy with a higher resultant indicating a higher magnitude; (2) the slope of change (θ in arc degree) which indicates the magnitude of the contribution of land use and climate changes with a higher slope reflecting a higher contribution of climate change; and (3) the relative contribution of land use and climate changes to stream flow alteration (C in %). In this study, we applied our approach to five catchments (Pidekso, Keduang, Samin, Madiun and Kening) ranging in size from 234 to 3759 km2 on Java, Indonesia. The hydro-climatic data cover the period 1975 - 2012 and the land use maps acquired from multi-temporal satellite imageries (i.e. for the years 1972, 1994, 2002 and 2013) were used and analyzed. The approach consists of four steps: (1) performing abrupt change detection on annual stream flow using Pettitt's test; (2) calculating the proportion of excess water and the proportion of excess energy for the period before and after the abrupt change of the stream flow; (3) calculating the quantitative contribution of land use and climate change to stream flow changes; (4) comparing the results with the Mann-Kendall trend analysis of variability in precipitation and potential evapotranspiration, and the land use change analysis. The results show that all catchments have a simultaneous increase of the proportion of excess water and energy for the period after the abrupt change compared to the period before the abrupt change. The Samin catchment gives the highest R value with a value of 0.9 followed by Pidekso catchment (0.7), Keduang catchment (0

  6. Model development based on a landscape oriented catchment unit concept

    NASA Astrophysics Data System (ADS)

    Cárdenas Gaudry, María.; Gutknecht, Dieter

    2010-05-01

    This paper is a companion paper to our project proposal "Hydrologic model framework for river basins with a range of hydroclimatic and bioclimatic conditions" (HS4.1). It intends to present a few ideas of how to bridge available concepts of landscape classification (as an example the Holdridge Life Zones classification scheme will be used) and hydrological approaches related to the Dominant Process Concept. The focus is on the development of landscape related indices that consider water balance characteristics (e.g.: the relationship ET/P), seasonality measures, and/or runoff generation process signatures at the landscape scale. Methods applied to consider runoff generation in hydrological modelling are commonly based on concepts such as the Hydrological Response Unit (HRU) concept (e.g. Flügel, 1995), the "hydrotop" concept (e.g. Reszler et al., 2006) and the Dominant Runoff Processes concept (DRP, e.g. Schmocker-Fackel and Scherrer, 2007). They are best suited to smaller scale catchment description. It is hypothesized here that additional/new concepts are necessary if the mechanismus that control runoff generation on a larger, i.e. regional scale should be captured. Hydrological reasoning and first results from regional studies indicate that appropiately chosen "signatures" can be found to characterise differences in the control of the runoff processes in different catchments situations. Examples might be "indicators" which include the soil moisture state of a basin or the event runoff coefficient derived from hydrological model simulatons or from runoff observations, respectly (e.g. Samuel et al. 2008; Merz & Blöschl, 2009a). The presentation will demostrate a few results from first studies on the above outlined concept. The study uses data from a set of Austrian catchments prepared for the studies reported in Merz & Blöschl (2009a). References: Flügel, W.-A. (1995): Delineating hydrological response units by geographical information system analyses for

  7. Space-time variability of precipitation in a montainous catchment of the Spanish Central System

    NASA Astrophysics Data System (ADS)

    Ruiz-Villanueva, V.; Bodoque, J. M.; Díez-Herrero, A.; Ballesteros, J. A.

    2009-04-01

    The catchment of the Cabrera Stream (15.5 km2) is on the northern slope of the Gredos Mountain Range in the Spanish Central System. The catchment altitude ranges in between 1923 and 735 masl and the mean slope of the watershed is 20 percent. There are six raingauges installed (one station per 2.6 km2) since 2004 in order to analyze the spatial and temporal characteristics of rainfall as an input of the calibrated distributed hydrometeorological models. They were also installed to record extreme rain events that could trigger sediment-laden flows like the hyperconcentrated one which took place on December 1997, which generated numerous infrastructure damages. The design of an instrumental network is very important in this kind of basins because of the high spatial-temporal rainfall variability. The accuracy of the registered values depends on the number and the location of the raingauges. For this reason, Multicriteria Evaluation was applied in a geographic information system in order to define the optimal position of the raingauges using factors such as topography, slope, aspect, curvature, geology, land uses, vegetation and accessibility. Eight heavy rainfall events, which took place from March 2005 to October 2008 in different seasons, have been considered to analyze the spatial and temporal rainfall variability during intense precipitations. The maximum intensity value of each event during different timespans was calculated (I24h, I12h, I1h, I30´, I10´) and different interpolations techniques (ordinary krigging, krigging with external drift, splines, IDW) were used in order to obtain areal rainfall estimations. These findings were calibrated with the data obtained from one of the stations (the one not used in interpolation) in order to analyze the best interpolation method. Then, the estimated values were compared with the observed values and a success rate was calculated. The results show the spatial and temporal characteristics of the rainfall dataset

  8. Earthflow sediment production and Holocene sediment record in a large Apennine catchment

    NASA Astrophysics Data System (ADS)

    Simoni, Alessandro; Ponza, Alessio; Picotti, Vincenzo; Berti, Matteo; Dinelli, Enrico

    2013-04-01

    Landscape evolution in active mountain chains can be dominated by gravitational slope movements. This is observed in a large portion of the Reno river catchment, Apennines, Italy, where weak rocks, such as clayshales, are subject to earthflows that control hillslope morphology and supply sediments to the channel network. In this paper, we evaluate the sediment flux generated by earthflows and compare it with Holocene-averaged deposition rates to assess the contribution of mass movements to landscape evolution. Present-day hillslope sediment flux is estimated by combining measured displacement rates (72 inclinometers) and spatial attributes of earthflows and historical frequency of reactivations. Averaged sediment yield (~ 1.6 x 103 t/km2/yr) compares well with similar studies on earthflow-dominated landscapes, despite notable differences in methodology. In the study area, the connectivity between hillslopes and the stream network is well developed and no significant sediment sinks influence the sediment transport processes. We document best estimates of regional sediment fluxes and related uncertainties, based on available data. Coarse limestone fragments, present in the clayshales, are used as a natural sediment tracer to allow a comparison with sedimentation rates taking place at the mouth of the intramontane catchment. Here, available borehole logs, 14C datings and stratigraphic correlations of the alluvial fan are used to obtain an estimate of the deposition that took place during Holocene times. Taking also into account the role of solute transport, sedimentation rates are compared to earthflow sediment production rates. Results show a good agreement and demonstrate that earthflows are the primary mass wasting process in these weak rock lithologies. We document best estimates of regional sediment fluxes and related uncertainties. Present earthflow sediment production outpaces Holocene-averaged sedimentation rates by a factor of two. The gap between sediment

  9. A virtual reality catchment for data assimilation experiments

    NASA Astrophysics Data System (ADS)

    Schalge, Bernd; Rihani, Jehan; Haese, Barbara; Baroni, Gabriele; Erdal, Daniel; Neuweiler, Insa; Hendricks-Franssen, Harrie-Jan; Geppert, Gernot; Ament, Felix; Kollet, Stefan; Cirpka, Olaf; Saavedra, Pablo; Han, Xujun; Attinger, Sabine; Kunstmann, Harald; Vereecken, Harry; Simmer, Clemens

    2016-04-01

    Current data assimilation (DA) systems often lack the possibility to assimilate measurements across compartments to accurately estimate states and fluxes in subsurface-land surface-atmosphere systems (SLAS). In order to develop a new DA framework that is able to realize this cross-compartmental assimilation a comprehensive testing environment is needed. Therefore a virtual reality (VR) catchment is constructed with the Terrestrial System Modeling Platform (TerrSysMP). This catchment mimics the Neckar catchment in Germany. TerrSysMP employs the atmospheric model COSMO, the land surface model CLM and the hydrological model ParFlow coupled with the external coupler OASIS. We will show statistical tests to prove the plausibility of the VR. The VR is running in a fully-coupled mode (subsurface - land surface - atmosphere) which includes the interactions of subsurface dynamics with the atmosphere, such as the effects of soil moisture, which can influence near-surface temperatures, convection patterns or the surface heat fluxes. A reference high resolution run serves as the "truth" from which virtual observations are extracted with observation operators like virtual rain gauges, synoptic stations and satellite observations (amongst others). This effectively solves the otherwise often encountered data scarcity issues with respect to DA. Furthermore an ensemble of model runs at a reduced resolution is performed. This ensemble serves also for open loop runs to be compared with data assimilation experiments. The model runs with this ensemble served to identify sets of parameters that are especially sensitive to changes and have the largest impact on the system. These parameters were the focus of subsequent ensemble simulations and DA experiments. We will show to what extend the VR states can be re-constructed using data assimilation methods with only a limited number of virtual observations available.

  10. Streamflow generation in a drying catchment outside Bangalore, India

    NASA Astrophysics Data System (ADS)

    Penny, G.; Thompson, S. E.; Srinivasan, V.; Peschel, J.; Young, S. N.; Jeremiah, K.; R, A.

    2015-12-01

    The causes of a dramatic reduction in surface flows in the TG Halli Catchment near Bangalore, India in the past forty years remain largely uncertain. The development of conceptual and process models is currently hampered by a fundamental lack of understanding of runoff generation mechanisms, and whether these mechanisms changed in concert with declining surface flow. We used stable water isotopes as tracers, measuring their concentrations in rainfall, soil water, and surface runoff. The isotopic profiles of runoff were very similar to rainfall, and displayed no evidence of mixing with soil water, leading us to conclude that infiltration excess runoff generation mechanisms were dominant, consistent with observed sharp rising and falling limbs in the regional hydrograph. This interpretation was supported by observations from nearly 100 surficial wells, which confirmed that water tables remained well below the level of the stream channel during the monsoon season. Infiltrometer measurements across different land uses in the catchment indicated broadly similar rates of infiltration capacity, suggesting that land use is unlikely to have altered the frequency with which infiltration excess runoff occurs. Changes in the occurrence of large storms over the 40 year period in which streamflow declines were observed are not sufficient to explain the decline in streamflow, if the runoff generation mechanism had not also changed during this period. We suggest that the results are consistent with the interpretation that a change in the dominant runoff generation mechanism has occurred simultaneously with the reductions in flow in the TG Halli catchment, potentially induced by the widespread expansion of groundwater pumping in the region.

  11. Export of arsenic from forested catchments under easing atmospheric pollution

    SciTech Connect

    Lucie Erbanova; Martin Novak; Daniela Fottova; Barbora Dousova

    2008-10-01

    Massive lignite burning in Central European power plants peaked in the 1980s. Dissolved arsenic in runoff from upland forest ecosystems is one of the ecotoxicological risks resulting from power plant emissions. Maxima in As concentrations in runoff from four forest catchments have increased 2-5 times between 1995 and 2006, and approach the drinking water limit (10 {mu}g L{sup -1}). To assess the fate of anthropogenic As, we constructed input/output mass balances for three polluted and one relatively unpolluted forest catchment in the Czech Republic, and evaluated the pool size of soil As. The observation period was 11 years, and the sites spanned a 6-fold As pollution gradient. Two of the polluted sites exhibit large net As export via runoff solutes (mean of 4-5 g As ha{sup -1} yr{sup -1} for the 11-year period; up to 28 g As ha{sup -1} yr{sup -1} in 2005). This contrasts with previous studies which concluded that forest catchments are a net sink for atmogenic arsenic both at times of increasing and decreasing pollution. The amount of exported As is not correlated with the total As soil pool size, which is over 78% geogenic in origin, but correlates closely with water fluxes via runoff. Net arsenic release is caused by an interplay of hydrological conditions and retreating acidification which may mobilize arsenic by competitive ligand exchange. The effects of droughts and other aspects of climate change on subsequent As release from soil were not investigated. Between-site comparisons indicate that most pollutant As may be released from humus. 24 refs., 7 figs., 1 tab.

  12. Aged Riverine Particulate Organic Carbon in Four UK Catchments

    NASA Astrophysics Data System (ADS)

    Adams, Jessica; Tipping, Edward; Bryant, Charlotte; Helliwell, Rachel; Toberman, Hannah; Quinton, John

    2016-04-01

    The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of sample