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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. Neural networks forecast in small catchments with transfer of network parameters

    NASA Astrophysics Data System (ADS)

    Maca, P.; Havlicek, V.; Hermanovsky, M.; Horacek, S.; Pech, P.

    2009-04-01

    This contribution deals with neural network approach for short term forecast on small catchments. The applied methodology is based on theory of multilayer perceptron (MLP), feed forward neural network with back propagation optimization procedure was tested in order to explore the possibilities to transfer parameters between different catchments. Supervised optimization of network parameters and structure was investigated. A software tool was created for these research and operative purposes. The hourly discharges and rainfall data of real flood events served as an input to MLP. Seven catchments with areas, which range from 10 to 250 square kilometres and which are situated in the east part of the Czech Republic, were selected. The input data were normalized by parametric method. Variable configuration of neural network was tested in number of modes represented by different combination of learning and testing data sets. The analysis focuses on ability of the model to forecast the flood event with different peak discharge magnitudes. This should be achieved in both application steps - MLP learning and testing within given catchment and in step of parameter transfer of well learned network to another catchment. The length of prediction ranged from one hour to six hours ahead. The results showed that the model is capable to provide satisfying short term discharge forecast for the most of studied cases, including successful parameter transfer among different catchments. This was accomplished by using optimization of parameters which determine not only the structure and behaviour of applied network but also the transformation of input data.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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. PMID:19700825

  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. Characteristics of nitrogen retention along the river network of upper Xin'anjiang catchment in China

    NASA Astrophysics Data System (ADS)

    Wang, A.; Yang, D.; Tang, L.

    2014-12-01

    Nitrogen (N) originates mainly from the non-point source (NPS) in the headwaters of many rivers. Understanding the nitrogen retention characteristics along the river network is important for land management in order to implement water resources protection. This study employs a geomorphology based non-point source pollution (GBNP) model to simulate the hillslope hydrological processes, sediment and pollutants transportation in the upper Xin'anjiang catchment in recent 10 years from 2001 to 2010. Calibration and validation of the GBNP model are carried out carefully using the observed discharge, sediment and total nitrogen (TN) concentrations at several hydrological gauges, and then the simulated results of the whole catchment are used to analyze the spatial and temporal distribution of nitrogen along the river networks with emphasis on its retention characteristics. The simulated results indicate that annual TN loaded from the hillslopes in the study catchment ranges from nearly 4000 ton to 11,000 ton and relatively higher TN load occurred in spring and summer. Average TN loads from hillslopes have significant positive correlation with the irrigated-cropland area (correlation coefficient =0.820), and significant negative correlation with the area of forest and grassland (correlation coefficient =-0.427 and -0.246). Seasonal nitrogen retention ratio in the river networks of study catchment in last 10 years varies from 0%-81%, and the streams of order 1 in the Horton-Strahler ordering system has the highest retention ratio and is followed by order 2, order 3 and order 4. The results also indicate that nitrogen retention ratio has positive correlation with river length and negative correlation with discharge and velocity. Scenario analysis of fertilizer application demonstrates that the nitrogen retention ratio increases logarithmically with the TN load and reach a maximum value rapidly.

  10. 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

  11. A social network approach to analyzing water governance: The case of the Mkindo catchment, Tanzania

    NASA Astrophysics Data System (ADS)

    Stein, C.; Ernstson, H.; Barron, J.

    The governance dimension of water resources management is just as complex and interconnected as the hydrological processes it aims to influence. There is an increasing need (i) to understand the multi-stakeholder governance arrangements that emerge from the cross-scale nature and multifunctional role of water; and (ii) to develop appropriate research tools to analyze them. In this study we demonstrate how social network analysis (SNA), a well-established technique from sociology and organizational research, can be used to empirically map collaborative social networks between actors that either directly or indirectly influence water flows in the Mkindo catchment in Tanzania. We assess how these collaborative social networks affect the capacity to govern water in this particular catchment and explore how knowledge about such networks can be used to facilitate more effective or adaptive water resources management. The study is novel as it applies social network analysis not only to organizations influencing blue water (the liquid water in rivers, lakes and aquifers) but also green water (the soil moisture used by plants). Using a questionnaire and semi-structured interviews, we generated social network data of 70 organizations, ranging from local resource users and village leaders, to higher-level governmental agencies, universities and NGOs. Results show that there is no organization that coordinates the various land and water related activities at the catchment scale. Furthermore, an important result is that village leader play a crucial role linking otherwise disconnected actors, but that they are not adequately integrated into the formal water governance system. Water user associations (WUAs) are in the process of establishment and could bring together actors currently not part of the formal governance system. However, the establishment of WUAs seems to follow a top-down approach not considering the existing informal organization of water users that are revealed

  12. 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

  13. 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

  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. 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

  16. Design and performance of a wireless sensor network for catchment-scale snow and soil moisture measurements

    NASA Astrophysics Data System (ADS)

    Kerkez, Branko; Glaser, Steven D.; Bales, Roger C.; Meadows, Matthew W.

    2012-09-01

    A wireless sensor network (WSN) was deployed as part of a water balance instrument cluster across a forested 1 km2headwater catchment in the southern Sierra Nevada of California. The network, which integrates readings from over 300 sensors, provides spatially representative measurements of snow depth, solar radiation, relative humidity, soil moisture, and matric potential. The ability of this densely instrumented watershed to capture catchment-scale snow depth and soil moisture distributions is investigated through comparison with three comprehensive gridded surveys and 1 day of detailed lidar snow data. Statistical analysis shows that the network effectively characterized catchment-wide distributions of snow depth, while offering a cost-effective, reliable, and energy-efficient means for collecting distributed data in real time. A temporal analysis of snow depth variability reveals that canopy cover is the major explanatory variable of snow depth and that under-canopy measurements persistently show higher variability compared to those in open terrain. An analysis of soil moisture shows lower variability at deeper soil depth and a correlation between mean soil moisture and variability for shallow soils. A three-phase design procedure was used to optimize the WSN deployment. First, as off-the-shelf performance of current WSN platforms for large-scale, long-term deployments cannot be guaranteed, statistics from a prototype deployment were analyzed. Two indicators of network performance, the packet delivery ratio and received signal strength indicator, showed that for our site conditions, a conservative 50 m node-to-node spacing would ensure low-power, reliable, and robust network communications. Second, results from the prototype were used to refine hardware specifications and to guide the layout of the full 57-node wireless network. Of these nodes, 23 were used actively for sensing, while the remaining 34 nodes were used as signal repeaters to ensure proper spatial

  17. Calibration of a catchment scale cosmic-ray probe network: A comparison of three parameterization methods

    NASA Astrophysics Data System (ADS)

    Baatz, R.; Bogena, H. R.; Hendricks Franssen, H.-J.; Huisman, J. A.; Qu, W.; Montzka, C.; Vereecken, H.

    2014-08-01

    The objective of this work was to assess the accuracy of soil water content determination from neutron flux measured by cosmic-ray probes under humid climate conditions. Ten cosmic-ray probes were set up in the Rur catchment located in western Germany, and calibrated by gravimetric soil sampling campaigns. Aboveground biomass was estimated at the sites to investigate the role of vegetation cover on the neutron flux and the calibration procedure. Three parameterization methods were used to generate site-specific neutron flux - soil water content calibration curves: (i) the N0-method, (ii) the hydrogen molar fraction method (hmf-method), and (iii) the COSMIC-method. At five locations, calibration measurements were repeated to evaluate site-specific calibration parameters obtained in two different sampling campaigns. At two locations, soil water content determined by cosmic-ray probes was evaluated with horizontally and vertically weighted soil water content measurements of two distributed in situ soil water content sensor networks. All three methods were successfully calibrated to determine field scale soil water content continuously at the ten sites. The hmf-method and the COSMIC-method had more similar calibration curves than the N0-method. The three methods performed similarly well in the validation and errors were within the uncertainty of neutron flux measurements despite observed differences in the calibration curves and variable model complexity. In addition, we found that the obtained calibration parameters NCOSMIC, N0 and NS showed a strong correlation with aboveground biomass.

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

    PubMed

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

    2015-08-01

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

  19. Untangling hydrological pathways and nitrate sources by chemical appraisal in a stream network of a reservoir catchment

    NASA Astrophysics Data System (ADS)

    Yevenes, M. A.; Mannaerts, C. M.

    2012-03-01

    The knowledge of water source contributions to streamflow is important for understanding chemical contamination origins and the status of biogeochemical cycling in stream networks of catchments. In this study, we evaluated whether a limited number of spatially distributed geochemical tracer data sampled during different hydrological seasons were sufficient to quantify water flow pathways and nitrate sources in a catchment. Six geochemical water constituents (δ2H, δ18O, Cl-, SO2-4, Na+, NO-3 and K+) of precipitation, stream water, alluvial sediment pore water and shallow groundwater of a 352 km2 agricultural catchment in the Alentejo region of Portugal were analysed. Exploratory data analysis and end-member mixing analysis (EMMA) were performed to estimate the water source mixing proportions. Residual analysis of principal components was used to identify the appropriate geochemical tracers and the number of end-members (water sources and flow paths), and their proportional contributions to streamflow were quantified. Spearman's rank correlation analysis was further used to identify nitrate origins in the streamflow. Results showed that, when using data from both wet and dry seasons, streamflow chemistry was strongly influenced by shallow groundwater. When only wet season data were modelled, streamflow chemistry was controlled and generated by three end-members: shallow groundwater, alluvial sediment pore water and precipitation. Isotope signatures of stream water were located mostly below the local meteoric water line (LMWL) and plotted along a local evaporation line (LEL), reflecting the permanence in the streamflow of shallow groundwater subjected to prior evaporation. Interpretation of isotope signatures during summer showed an isotopic enrichment in both streamflow and shallow groundwater. Measured and historical stream nitrate concentrations appeared to be strongly related to shallow groundwater. In addition, two hydrochemical data outliers for almost every

  20. Flow simulation and erosion assessment in a ditch network of a drained peatland forest catchment in Eastern Finland

    NASA Astrophysics Data System (ADS)

    Haahti, Kersti; Koivusalo, Harri; Younis, Bassam; Stenberg, Leena

    2014-05-01

    One third of the land area in Finland is covered by peatlands and today 4.5 million ha of peatlands are drained for forestry purposes. In order to sustain forest productivity, ditch networks are maintained annually on an area of approximately 60 000 ha. The suspended solid (SS) load from drained peatland forest sites after ditch network maintenance causes one of the largest strains on the water system by forestry in Finland. Understanding the hydraulic processes in newly maintained ditch networks is necessary for quantifying the SS load generation and transport in the source areas. In this study we developed a hydraulic unsteady-flow model to predict the behavior of flow in a drainage network in a boreal forested peatland site. The input to this model was in the form of a discharge hydrograph that was produced by a hydrological model (FEMMA). The simulations were performed using the algorithm of Zhu et al. (2011) for unsteady flows in a network of channels. In this iterative procedure, the Saint-Venant equations that govern the flow in each of the network channels were solved separately, and the flow depths at the junction-points were corrected using the method of characteristics. The algorithm was programmed using the numeric computing environment MATLAB by MathWorks. Based on the hydraulic conditions produced by the model, erosion risk within the network was evaluated. The model was applied to a peatland catchment drained for forestry in Koivupuro in Eastern Finland (63°53' N, 28°40' E). In August 2011, most of the Koivupuro catchment ditch network was maintained creating simultaneously a smaller nested catchment (area 5.2 ha) which was the focus of this study. The ditch network consisted of 15 branches, altogether 1.6 km in length, and 8 junctions. The model performance was evaluated against flow depth measurements at 5 locations in the network. The simulations in the small ditches of Koivupuro with mostly very low flow rate (< 0.05 m3/s) introduced its

  1. 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.

  2. Temporal Change in Discharge Response in Unregulated Swedish Catchments - Quantifying Potential Effects of Anthropogenic Modifications in Stream Network Properties on Flow Time Distributions

    NASA Astrophysics Data System (ADS)

    Worman, A. L. E.; Åkesson, A. M.; Riml, J.; Seibert, J.

    2015-12-01

    Fourier spectral analysis of daily discharge time-series with a duration of 55-110 years in 79 unregulated catchments revealed that the discharge power spectrum slope has gradually increased (statistically significant at the 99% confidence level) over time. For the locations for which historical meteorological observations is available (the 41 southernmost catchments), the evaluation theoretically accounted for fluctuation in the precipitation power spectrum. The results indicate that (local) land-use changes within the catchments may have a relatively more important role (than climate change) for the temporal changes shown in the discharge power spectra. With a basis in stream network maps from present day in two different resolutions as well as a historical map from the 1880's, anthropogenic modifications, in terms of the flow paths within the stream networks, were identified for an agricultural catchment in southern Sweden. Through scenario modelling using a 1-D distributed routing model, the influence of common anthropogenic activities such as e.g. straightening of flowpaths, widening of stream channels to avoid damming and excavation to eliminate thresholds in the stream bottom topography, on the travel time distributions within a stream network were quantified. The map studies showed that the average flow path length had decreased over the last century. The study also shows that all of the studied anthropogenic factors can potentially have a substantial impact on the travel times through the stream networks - by decreasing the average travel time as well as by decreasing the variance. These types of temporal changes in stream network properties leads to a diminished possibility to attenuate peakflows, and are expected to have a substantial influence on discharge hydrographs. This study verifies the hypothesis that anthropogenic impacts of stream networks can influence the hydrological response in catchments, and that land-use changes on a local scale may be

  3. Untangling hydrological pathways and nitrate diffusive sources by chemical appraisal in a stream network of a reservoir catchment

    NASA Astrophysics Data System (ADS)

    Yevenes-Burgos, M. A.; Mannaerts, C. M.

    2011-03-01

    Stable water isotopes and water hydrochemistry of a catchment in the Alentejo region, south Portugal, were analysed to investigate source origins of water and nitrate flows towards a reservoir. The 353 km2 headwater catchment of Roxo river, is strongly influenced by agricultural impacts, and high variations in water and chemical inflows into an important drinking and irrigation water supply (108 m3) are observed. This leads to regular disputes on water quantity and quality amongst local authorities and population. Three sampling campaigns in different seasons were used to address the temporal and spatial variations in stream and groundwater hydrochemistry and water isotopic signatures. A total of 27 sampling points from the stream network, shallow groundwater and reservoir were used. Isotopic signatures and chemistry of precipitation were obtained from local data of the Global Network of Isotopes in Precipitation (GNIP) and the Global Atmosphere Watch (GAWSIS) network. Other meteorological, hydrological and environmental datasets were obtained from local authorities. The stable water isotopes deuterium (δ2H), oxygen-18 (δ18O) together with chloride (Cl-) and sulphate (SO42-) were used as environmental tracers in the hydrological pathways. Water pathways were then related with nitrate concentrations to elucidate potential relationships between the water and nutrient sources. Interpretation of isotope signatures showed a high degree of isotope enrichment in both surface (stream flow) and shallow groundwater. For the entire period, most of stream waters were located right of the global meteoric water line or GMWL and plotted along a local evaporation line (LEL) established for the study area. The LEL showed slopes similar to stream systems in other dry environments. Monthly stream flow and precipitation, seasonal isotope compositions and major ion chemistry data were used for an evaluation of the relative contribution of water sources using an end-member mixing

  4. 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

  5. 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

  6. Network analysis of sediment cascades derived from digital geomorphological maps - a comparative study of three catchments in the Austrian and Swiss Alps

    NASA Astrophysics Data System (ADS)

    Heckmann, Tobias; Hilger, Ludwig; Meßenzehl, Karoline; Hoffmann, Thomas; Schwanghart, Wolfgang; Götz, Joachim; Buckel, Johannes

    2014-05-01

    Sediment fluxes in alpine environments are strongly conditioned by sediment storage, resulting in non-linear feedbacks between sediment input and output. Recently, geomorphological mapping in alpine regions has focused on the static distribution of sediment storage units, neglecting the dynamic links of geomorphic processes units along the sediment pathways. Here we present an approach i) to analyse the sediment connectivity of a catchment based on coupling relationships of neighbouring storage units, and ii) to re-evaluate existing geomorphological maps in terms of the network structure. The approach is applied in three catchments in the European Alps, which were mapped in previous geomorphological studies: i) the Gradenbach catchment (Upper Tauern, Carinthia, Austria), ii) the (upper) Kaunertal (Ötztal Mountains, Tyrolia, Austria) and the Val Müschauns (Engadine, Switzerland). While the morphology of all study areas is predominantly controlled by former glaciations, only the two Austrian areas feature recent glaciers. The available geomorphic maps consist of non-overlapping polygons representing geomorphic process units of erosion, sediment transport and deposition. Mapping was conducted in the field, and supported by digital orthophotos and derivatives of LiDAR-based digital elevation models (slope, curvature, aspect, shaded relief, etc.). Based on the observation of diagnostic features, the geomorphic coupling state of every pair of adjacent landforms, i.e. the existence of sediment transfer across their common boundary, was assessed and mapped. Taking the landforms as nodes, and the inferred coupling relationships as edges, a graph model of the sediment transfer system is established. Graph theory offers a versatile toolbox for the analysis of the spatial structure of sediment cascades in different ways: Nodes are analysed for the number of incoming and outgoing edges, and classified as sediment source, sink, or link. Depending on the spatial and functional

  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. 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

  9. 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

  10. 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

  11. An Explicit Representation of High Resolution River Networks using a Catchment-based Land Surface Model with the NHDPlus dataset for California Region

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Kim, H.; Famiglietti, J. S.

    2011-12-01

    The main motivation of this study is to characterize how accurately we can estimate river discharge, river depth and inundation extent using an explicit representation of the river network with a catchment-based hydrological and routing modeling system (CHARMS) framework. Here we present a macroscale implementation of CHARMS over California. There are two main components in CHARMS: a land surface model based on National Center Atmospheric Research Community Land Model (CLM) 4.0, which is modified for implementation on a catchment template; and a river routing model that considers the water transport of each river reach. The river network is upscaled from the National Hydrography Dataset Plus (NHDPlus) to the Hydrologic Unit Code (HUC8) river basins. Both long-term monthly and daily streamflow simulation are generated and show reasonable results compared with gage observations. With river cross-section profile information derived from empirical relationships between channel dimensions and drainage area, river depth and floodplain extent associated with each river reach are also explicitly represented. Results have implications for assimilation of surface water altimetry and for implementation of the approach at the continental scale.

  12. 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

  13. 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

  14. Incorporating flood event analyses and catchment structures into model development

    NASA Astrophysics Data System (ADS)

    Oppel, Henning; Schumann, Andreas

    2016-04-01

    The space-time variability in catchment response results from several hydrological processes which differ in their relevance in an event-specific way. An approach to characterise this variance consists in comparisons between flood events in a catchment and between flood responses of several sub-basins in such an event. In analytical frameworks the impact of space and time variability of rainfall on runoff generation due to rainfall excess can be characterised. Moreover the effect of hillslope and channel network routing on runoff timing can be specified. Hence, a modelling approach is needed to specify the runoff generation and formation. Knowing the space-time variability of rainfall and the (spatial averaged) response of a catchment it seems worthwhile to develop new models based on event and catchment analyses. The consideration of spatial order and the distribution of catchment characteristics in their spatial variability and interaction with the space-time variability of rainfall provides additional knowledge about hydrological processes at the basin scale. For this purpose a new procedure to characterise the spatial heterogeneity of catchments characteristics in their succession along the flow distance (differentiated between river network and hillslopes) was developed. It was applied to study of flood responses at a set of nested catchments in a river basin in eastern Germany. In this study the highest observed rainfall-runoff events were analysed, beginning at the catchment outlet and moving upstream. With regard to the spatial heterogeneities of catchment characteristics, sub-basins were separated by new algorithms to attribute runoff-generation, hillslope and river network processes. With this procedure the cumulative runoff response at the outlet can be decomposed and individual runoff features can be assigned to individual aspects of the catchment. Through comparative analysis between the sub-catchments and the assigned effects on runoff dynamics new

  15. 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. PMID:11424936

  16. A differential equation for specific catchment area

    NASA Astrophysics Data System (ADS)

    Gallant, John C.; Hutchinson, Michael F.

    2011-05-01

    Analysis of the behavior of specific catchment area in a stream tube leads to a simple nonlinear differential equation describing the rate of change of specific catchment area along a flow path. The differential equation can be integrated numerically along a flow path to calculate specific catchment area at any point on a digital elevation model without requiring the usual estimates of catchment area and width. The method is more computationally intensive than most grid-based methods for calculating specific catchment area, so its main application is as a reference against which conventional methods can be tested. This is the first method that provides a benchmark for more approximate methods in complex terrain with both convergent and divergent areas, not just on simple surfaces for which analytical solutions are known. Preliminary evaluation of the D8, M8, digital elevation model networks (DEMON), and D∞ methods indicate that the D∞ method is the best of those methods for estimating specific catchment area, but all methods overestimate in divergent terrain.

  17. Spectral Analysis in Catchment Hydrology and Geochemistry

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.; Feng, X.; Renshaw, C. E.; Neal, C.

    2001-12-01

    Spectral analysis of chemical tracer time series can be used to probe the internal workings of catchments. It has recently been shown that catchments act as fractal filters for inert chemical tracers like chloride, converting "white noise" rainfall chemistry inputs into fractal "1/f noise" runoff chemistry time series (Kirchner et al., 2000). This implies that catchments have long-tailed travel time distributions, and thus retain soluble contaminants for unexpectedly long timespans. Long-term monitoring data from North America, Britain, and Scandinavia show that this fractal behavior characterizes a wide array of catchments. How can this fractal scaling arise in such diverse settings? One can show that advection and dispersion of spatially distributed rainfall tracer inputs will generate fractal tracer time series, as long as the flow system is highly dispersive (Kirchner et al., in press). This implies that subsurface flow in small catchments is dominated by large conductivity contrasts, such as arise from macropores, fracture networks, and similar large-scale heterogeneities in subsurface conductivity. One can also use spectral methods to analyze long-term time series of water fluxes in rainfall and streamflow. Spectral analysis of hydrologic time series measures the downslope propagation of the hydraulic potential waves that mobilize runoff, whereas spectral analysis of tracer time series clocks the propagation of water itself through the catchment. Water fluxes in streamflow exhibit non-fractal scaling, instead of the fractal 1/f scaling shown by chemical tracers. These observations imply that hydrologic signals are transmitted downslope more rapidly, and with much less dispersion, than chemical tracer signals are. Thus small upland catchments transmit hydraulic potentials (which drive runoff) much less dispersively than they transport water itself. These observations provide important constraints for theoretical models of subsurface flow and transport in

  18. 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

  19. 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

  20. 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

  1. A flexible multi-model framework for catchment-specific calibration, and application to diverse European catchments

    NASA Astrophysics Data System (ADS)

    Kavetski, Dmitri; Fenicia, Fabrizio; Savenije, Hubert H. G.

    2010-05-01

    If one accepts that a single model structure cannot accommodate the wide spectrum of catchment dynamics encountered in practice, the need for flexible hydrological models becomes evident. Here, we present SUPERFLEX, a hydrological modelling system that represent the catchment as a network of conceptual elements, including nonlinear reservoirs and routing components, with connectivity, constitutive relations and parameterizations specified by the Hydrologist using a priori insights into the catchment of interest, and refined based on calibration results. The model equations are implemented using robust numerical approaches, and the entire SUPERFLEX system is integrated into a Bayesian inference suite, permitting hypotheses regarding forcing/response data to be evaluated and refined as part of the model inference. The application of the SUPERFLEX approach to a range of European catchments is presented, demonstrating how the ability to adjust the model structure to specific catchments allows improved representatation of its key hydrological processes, and consequently improved model performance.

  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. Terrain representation impact on periurban catchment morphological properties

    NASA Astrophysics Data System (ADS)

    Rodriguez, F.; Bocher, E.; Chancibault, K.

    2013-04-01

    SummaryModelling the hydrological behaviour of suburban catchments requires an estimation of environmental features, including land use and hydrographic networks. Suburban areas display a highly heterogeneous composition and encompass many anthropogenic elements that affect water flow paths, such as ditches, sewers, culverts and embankments. The geographical data available, either raster or vector data, may be of various origins and resolutions. Urban databases often offer very detailed data for sewer networks and 3D streets, yet the data covering rural zones may be coarser. This study is intended to highlight the sensitivity of geographical data as well as the data discretisation method used on the essential features of a periurban catchment, i.e. the catchment border and the drainage network. Three methods are implemented for this purpose. The first is the DEM (for digital elevation model) treatment method, which has traditionally been applied in the field of catchment hydrology. The second is based on urban database analysis and focuses on vector data, i.e. polygons and segments. The third method is a TIN (or triangular irregular network), which provides a consistent description of flow directions from an accurate representation of slope. It is assumed herein that the width function is representative of the catchment's hydrological response. The periurban Chézine catchment, located within the Nantes metropolitan area in western France, serves as the case study. The determination of both the main morphological features and the hydrological response of a suburban catchment varies significantly according to the discretization method employed, especially on upstream rural areas. Vector- and TIN-based methods allow representing the higher drainage density of urban areas, and consequently reveal the impact of these areas on the width function, since the DEM method fails. TINs seem to be more appropriate to take streets into account, because it allows a finer

  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. Design and development of a wireless sensor network to monitor snow depth in multiple catchments in the American River basin, California: hardware selection and sensor placement techniques

    NASA Astrophysics Data System (ADS)

    Kerkez, B.; Rice, R.; Glaser, S. D.; Bales, R. C.; Saksa, P. C.

    2010-12-01

    A 100-node wireless sensor network (WSN) was designed for the purpose of monitoring snow depth in two watersheds, spanning 3 km2 in the American River basin, in the central Sierra Nevada of California. The network will be deployed as a prototype project that will become a core element of a larger water information system for the Sierra Nevada. The site conditions range from mid-elevation forested areas to sub-alpine terrain with light forest cover. Extreme temperature and humidity fluctuations, along with heavy rain and snowfall events, create particularly challenging conditions for wireless communications. We show how statistics gathered from a previously deployed 60-node WSN, located in the Southern Sierra Critical Zone Observatory, were used to inform design. We adapted robust network hardware, manufactured by Dust Networks for highly demanding industrial monitoring, and added linear amplifiers to the radios to improve transmission distances. We also designed a custom data-logging board to interface the WSN hardware with snow-depth sensors. Due to the large distance between sensing locations, and complexity of terrain, we analyzed network statistics to select the location of repeater nodes, to create a redundant and reliable mesh. This optimized network topology will maximize transmission distances, while ensuring power-efficient network operations throughout harsh winter conditions. At least 30 of the 100 nodes will actively sense snow depth, while the remainder will act as sensor-ready repeaters in the mesh. Data from a previously conducted snow survey was used to create a Gaussian Process model of snow depth; variance estimates produced by this model were used to suggest near-optimal locations for snow-depth sensors to measure the variability across a 1 km2 grid. We compare the locations selected by the sensor placement algorithm to those made through expert opinion, and offer explanations for differences resulting from each approach.

  6. A methodological comparison of catchment storages in mountainous catchments

    NASA Astrophysics Data System (ADS)

    Weiler, Markus; Staudinger, Maria; Stölzle, Michael; Seeger, Stefan; Seibert, Jan; Stahl, Kerstin

    2015-04-01

    One of the most important functions of catchments is the temporary storage of water, which directly influences runoff dynamics, rainfall-runoff transformation, partitioning of evaporation and runoff fluxes, and accessibility of water to plants. Generally, a large catchment storage is considered beneficial and in particular increases the transit times and hence the buffer functioning related to water quality. Many different methods have been developed to assess catchment storage, however, there are hardly any direct comparisons of several of these methods. One challenge is the definition of water storage, while some methods allow estimation of the entire water storage in a catchment, other methods quantify only the dynamic storage. In addition, most studies focused more on lowland catchments with rain-dominated runoff regimes and observed groundwater fluctuations. Furthermore, these studies often focus on one or two catchments, but do not consider the influence of different climates on the relevance of water storage in the catchment. We applied a range of different methods to assess catchment storage characteristics in 18 catchments in the Swiss Alps, ranging from 500 to 2000m of mean elevation and hence from rainfall- to snowmelt dominated runoff regimes. The first method use only discharge information during recession periods and with varying approaches to extract discharge and storage changes between high flow and low flow, the dynamic catchment storage can be derived. In the next methods the conceptual hydrological model HBV is calibrated to the runoff dynamics and the dynamic and total catchment storages of the different compartments are being evaluated. The last methods are based on stable water isotope data analysis. We use the model TRANSEP to derive the dynamic storage as well as the total water storage of the catchment based on the transit times using several years of fortnightly isotope data in streamflow. The results show that the derived catchment

  7. Catchment controls on solute export

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  8. 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

  9. 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.

  10. Internally Drained Supraglacial River Catchments on the Southwest Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Yang, K.; Smith, L. C.; Chu, V. W.; Pitcher, L. H.; Gleason, C. J.

    2015-12-01

    Internally drained catchments are the hydrologic units on the Greenland ice sheet (GrIS) surface that collect and drain meltwater into moulins or supraglacial lakes without out flows. Understanding the spatial pattern of these internal catchments is critical, which can provide key information about how supraglacial meltwater is transported and released on the ice surface. This study proposed an automatic approach to detect supraglacial hydrologic features (rivers, lakes, moulins, and internal catchments) located at southwest GrIS from Landsat-8 OLI panchromatic imagery. A total of 800 internal catchments are delineated and the average catchment size (river network length) is found to increase with elevations. In addition, moulins are the prime way to drain internal catchments and the average moulin densities decrease with elevations. Adaptive depression area thresholds are calculated to achieve optimal match between DEM-modeled and image-detected internal catchment patterns. The pattern of these image-detected internal catchments also indicates that: 1) not all the DEM-modeled topographic depressions act as meltwater sinks; 2) moulin distribution greatly impacts the internal catchment patterns; and 3) topographic depressions can be connected downstream without being fully filled, changing the fragmentary of the internal catchments.

  11. Investigating dominant processes on small poorly gauged catchments: an inter-comparison approach for catchment similarity study

    NASA Astrophysics Data System (ADS)

    Crabit, Armand; Colin, François; Moussa, Roger; Lagacherie, Philippe

    2010-05-01

    's density and water depth. Results show that the use of roughness coefficient values presented in the literature often induces overestimation in flow velocities calculation. This could be mainly explained by effective roughness which depends on the relative submergence of vegetation. Hydrological indicators were derived from estimated discharges: runoff coefficient, rising time, lag-time, peak runoff, runoff threshold. In spite of the associated uncertainty, indicators allow to discriminate catchments according to functions of partition, release and storage. The second step was to evaluate the efficiency of a catchment classification based on similarity assumptions. The classification highlights an obvious spatial hydrological variability on the studied region. This new approach shows the appeal to use a catchment network, even when poorly gauged, to gain understanding of processes driving hydrological responses.

  12. 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

  13. 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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Martin, Peter

    1991-11-01

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

  16. 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

  17. A simple model to assess nitrogen and phosphorus contamination in ungauged surface drainage networks: application to the Massaciuccoli Lake Catchment, Italy.

    PubMed

    Pistocchi, C; Silvestri, N; Rossetto, R; Sabbatini, T; Guidi, M; Baneschi, I; Bonari, E; Trevisan, D

    2012-01-01

    Modeling is a common practice to evaluate factors affecting water quality in environmental systems impaired by point and nonpoint losses of N and P. Nevertheless, in situations with inadequate information, such as ungauged basins, a balance between model complexity and data availability is necessary. In this paper, we applied a simplified analytical model to an artificially drained floodplain in central-western Italy to evaluate the importance of different nutrient sources and in-stream retention processes and to identify critical source areas. We first considered only a set of chemical concentrations in water measured from February through May 2008 and from November 2008 through February 2009. We then broadened available data to include water discharge and hydraulic-head measurements to construct a hydrogeological model using MODFLOW-2000 and to evaluate the reliability of the simplified method. The simplified model provided acceptable estimates of discharge (ranging from 0.03-0.75 m s) and diffuse nutrient inputs from water table discharge and in-stream retention phenomena. Estimates of PO-P and total P retention (ranging from 1.0 to 0.6 μg m s and from 1.18 to 0.95 μg m s for PO-P and total P, respectively) were consistent with the range of variability in literature data. In contrast, the higher temporal variability of nitrate concentrations decreased model accuracy, suggesting the need for more intensive monitoring. The model also separated the dynamics of different reaches of the drainage network and identified zones considered critical source areas and buffer zones where pollutant transport is reduced. PMID:22370417

  18. 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

  19. 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.

  20. Dispersion mechanisms and the effect of parameter uncertainty on hydrologic response in urban catchments

    NASA Astrophysics Data System (ADS)

    Cantone, Joshua; Schmidt, Arthur

    2011-05-01

    The link between river network structure and hydrologic response for natural watersheds has been the subject of ongoing research for the past 30 years. In this paper we investigate the link between sewer network structure and hydrologic response in urban catchments. It has been shown in natural watersheds that there are dispersion mechanisms that contribute to the impulse response function of the catchment: hydrodynamic dispersion, geomorphologic dispersion, and hydrodynamic dispersion. We introduce a fourth dispersion mechanism, intrastate dispersion, which accounts for the variance in conduit (e.g., slope, length, diameter, etc.) and overland region input parameters (e.g., slope, area, imperviousness, etc.) within an order. This dispersion mechanism is found to be the second largest contributor to the total dispersion in the urban catchments analyzed, contributing less than hydrodynamic dispersion but more than kinematic and geomorphologic dispersion. This is primarily a result of the shorter network travel times observed in urban catchment. The dispersion mechanisms are incorporated in the Illinois Urban Hydrologic Model, which is a recently developed probabilistic approach for predicting the hydrologic response in highly urbanized catchments. Furthermore, an analysis is performed to help better understand the uncertainty in the predicted hydrologic response that is introduced by spatial variation in conduit and overland input parameters. It is identified that conduit slope and length are the greatest sources of uncertainty in the predicted direct runoff hydrograph for the CDS-51 catchment in the village of Dolton, Illinois, and the CDS-36 catchment in the city of Chicago, Illinois.

  1. 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

  2. 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.

  3. Comparison of subsurface connectivity in Alpine headwater catchments

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. A catchment-scale model of mountain stream channel morphologies in southeast Australia

    NASA Astrophysics Data System (ADS)

    Thompson, Chris; Croke, Jacky; Takken, Ingrid

    2008-03-01

    The position of mountain streams high in the channel network and their proportional dominance mean that channel modifications and adjustments within these systems will have important implications for downstream processes and linkages. This study develops an analysis framework for examining the catchment-scale distribution of reach morphologies, and the relationship among reach type, catchment lithology and flow competence in southeast Australian mountain streams. The analysis framework is applied to three catchments which have contrasting proportions of the two dominant lithologies of the region, Devonian granites and Ordovician metasediments. The model successfully delineated 68% of reach types, and the resultant spatial maps allowed the effects of stream network position and catchment specific controls on channel morphology to be evaluated. Maximum lengths of the majority of reach morphology types were in second-order streams and the maximum number of morphology types (six) was present in third-order streams, with dramatic reductions in reach type variability as the network expands. The position of catchment lithology within the channel network structure was recognized as more important than the aerial extent of a particular lithology on the distribution and abundance of reach morphologies. The model provides an important tool in the management of channel networks for the protection or restoration of ecological diversity, by identifying river segments and tributaries with high morphological diversity.

  10. 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

  11. 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

  12. Modeling of matters removal from swampy catchment

    NASA Astrophysics Data System (ADS)

    Inishev, N. G.; Inisheva, L. I.

    2010-05-01

    This work shows the results of fixed study of geochemical conditions in the system of landscape oligotrophic profile at Vasyugan mire spurs, and also we make an approach to processes modelling of compounds removal from swampy catchment. During investigation of symbolic model of chemical matters removal from the surface of a catchment basin and their movement along the channel network it was taken into account that removal of chemical elements during the period of spring flood and rain high waters occur mainly with overland flow. During calculation of dissolved matters movement the following admissions take place: 1. The problem is solved at one-dimension set-up. Concentration of investigated components is taken as averaged one along the flow cross section or effective area of slope cross-section for overland runoff, i.e. it changes only lengthways and in time. 2. It is considered that dissolved matters spread due to movement of water and together with its particles. 3. Processes of water self-clarification are not considered. The model is calculated on the basis of discharge of the investigated ingredient, i.e. matter mass moving through the given flow cross-section into time unit. This is the peculiarity of the model. Matter removal together with water flow is determined if necessary. Everyday impurity consumptions and its concentration can be estimated at the outlet at the moment of time according to convolution integral. Estimation of overland runoff and water inflow into the channel network is based on the mathematic model of outflow formation from peatland areas which considers basic processes carrying out at catchment and basin channel network. Stored moisture estimation of snow cover is taken according to snow survey data before snow melting. Everyday water supply to the surface of water collection was determined according to the results of snow melt intensity estimation by the methods of temperature coefficient and water yield from snow (A.G. Kovzel). All

  13. Comparison of Multi-Scale Digital Elevation Models for Defining Waterways and Catchments Over Large Areas

    NASA Astrophysics Data System (ADS)

    Harris, B.; McDougall, K.; Barry, M.

    2012-07-01

    Digital Elevation Models (DEMs) allow for the efficient and consistent creation of waterways and catchment boundaries over large areas. Studies of waterway delineation from DEMs are usually undertaken over small or single catchment areas due to the nature of the problems being investigated. Improvements in Geographic Information Systems (GIS) techniques, software, hardware and data allow for analysis of larger data sets and also facilitate a consistent tool for the creation and analysis of waterways over extensive areas. However, rarely are they developed over large regional areas because of the lack of available raw data sets and the amount of work required to create the underlying DEMs. This paper examines definition of waterways and catchments over an area of approximately 25,000 km2 to establish the optimal DEM scale required for waterway delineation over large regional projects. The comparative study analysed multi-scale DEMs over two test areas (Wivenhoe catchment, 543 km2 and a detailed 13 km2 within the Wivenhoe catchment) including various data types, scales, quality, and variable catchment input parameters. Historic and available DEM data was compared to high resolution Lidar based DEMs to assess variations in the formation of stream networks. The results identified that, particularly in areas of high elevation change, DEMs at 20 m cell size created from broad scale 1:25,000 data (combined with more detailed data or manual delineation in flat areas) are adequate for the creation of waterways and catchments at a regional scale.

  14. 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

  15. 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.

  16. Integrated monitoring of nitrogen dynamics in contrasting catchments

    NASA Astrophysics Data System (ADS)

    Schwientek, M.; Fleischer, M.

    2012-04-01

    The research institute WESS (Water & Earth System Science) is monitoring three adjacent meso-scale catchments (72 - 140 km2) in southwest Germany with respect to water quantity and quality. Due to their spatial proximity, the studied catchments are similar regarding climatic conditions and water balance. Geology is characterized by sedimentary rocks which are partly karstified. The catchments contrast strongly in land use and show a range from predominantly agriculture to almost exclusively forestry. In this context, a special focus of our research is the distinction of matter coming from the catchment area versus substances stemming from urban point sources. One important compound representing inputs from the catchment area is nitrogen. Nitrogen is an essential nutrient governing plant growth. If available in excess it leads to eutrophication and is therefore one of the globally most widespread contaminants in aquatic ecosystems. Transport of human-derived nitrogen through landscapes including urban areas to the oceans predominantly occurs via river network systems. Hence, monitoring of nitrogen fluxes in streams and rivers reveals mechanisms and dynamics of its transport and gives also insight into hydrologic processes which influence the mobilization of nitrogen. Presently, the catchments are equipped with online probes enabling high resolution monitoring of nitrate concentrations and other parameters. We found that average nitrate concentrations in stream water perfectly reflect the portion of fertilized arable land. The dynamics of N transport, however, largely depends on the hydrologic system and is driven by the dominating runoff generation processes. The interplay between different hydrological storages, which eventually also act as N pools, turns out to be decisive for the temporal variability of N concentrations in stream discharge. Inversely, the study of N transport dynamics can be used to infer the hydrologic mechanisms responsible for N mobilization

  17. Multivariate analysis of a small pleistocene catchment: tracing hydrological change

    NASA Astrophysics Data System (ADS)

    Boettcher, Steven; Merz, Christoph; Dannowski, Ralf

    2013-04-01

    The water budget of catchments in north-east Germany has decreased considerably over the last decades. Especially small catchments are affected due to the small amount of water stored within. Climate projections for the next decades hint to even more negative impacts on the water budgets of these catchments. Therefore, a new concept of water resource management for this region must be developed, including counter measures to extreme events such as low and high flow conditions. In order to manage a hydrological system one needs to know the typical behavior and be able to effectively counteract if needed. Within the network activity INKA-BB (Inovationsnetzwerk Klimaanpassung Brandenburg Berlin) dealing with possible adaptation measures to climate change in the Brandenburg and Berlin region, this study aims at identifying the typical hydraulic behavior of the Fredersdorfer Mühlenfließ catchment located north-east of Berlin as a basis for a sustainable water resource management concept. Established schemes are followed, including the application of numerical geochemical and hydraulic models as well as chemical graphical interpretation approaches. A common problem is the sparse spatial as well as temporal resolution of the data at hand. Here, these schemes are too inflexible and vague with respect to analyzing and parameterization of complex features used for identifying operative hydraulic-geochemical processes including intensive non-linear interactions. Hence, methods must be applied that are able to effectively utilize the limited information available. Ordination methods such as the Principle Component Analysis (PCA) or the non-linear Isometric Feature Mapping (Isomap) can provide such a tool. Ordination methods are used in order to derive a meaningful low-dimensional representation of a high-dimensional input data set. The approach is based on the hypothesis, that the amount of processes which explain the variance of the data is relative low although the

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

    NASA Astrophysics Data System (ADS)

    Petry, J.; Soulsby, C.

    2002-12-01

    strips can reduce the delivery of NH3-N and PO4-P by overland flow to stream channels during storm events, the management of N-rich storm runoff as NO3 via sub-surface drains would require significant interference with the drainage network. This could have a negative impact on agricultural production in the catchment.

  19. 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

  20. 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.

  1. Applying a GIS-based geomorphological routing model in urban catchments

    NASA Astrophysics Data System (ADS)

    Lhomme, Julien; Bouvier, Christophe; Perrin, Jean-Louis

    2004-12-01

    This paper discusses using a GIS-based geomorphological routing model to simulate urban stormwater runoff as an alternative to physically based routing models. Hydrological measurements have been carried out (1982-1984) in the urban catchment El Batan (52 km 2), which forms part of the city of Quito (Ecuador). As detailed data on the drainage network were available, a first attempt was made using, on the one hand, complete Barré de Saint-Venant equations in the network and, on the other, the linear reservoir model for the sub-catchments. Knowing both the geometry and hydraulics of the network was proved to achieve accurate simulations. However, collecting the network data and building the whole topology (reaches, nodes, sub-catchments) of this large urban catchment is very time-consuming work. Thus, grosser representations of the network to simulate runoff were tested, but it was found that the estimation of the concentration time becomes predominant, and may result in a significant loss of accuracy. Using a GIS-based geomorphological routing model is shown to be an efficient alternative: first, physical velocities in the reaches can be derived from slopes and upstream areas; second, the integration of these velocities in a distributed lag and route model produces flood simulations that are equivalent to the physically based routing model; third, Digital Elevation Models avoid most of the tedious preliminary tasks in building the catchment topology. Further investigation is required in order to evaluate variations in the lag parameter from one catchment to another.

  2. 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

  3. 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.

  4. 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.

  5. 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)

  6. 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

  7. 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

  8. 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

  9. Hydropedological insights when considering catchment classification

    NASA Astrophysics Data System (ADS)

    Bouma, J.; Droogers, P.; Sonneveld, M. P. W.; Ritsema, C. J.; Hunink, J. E.; Immerzeel, W. W.; Kauffman, S.

    2011-06-01

    Soil classification systems are analysed to explore the potential of developing classification systems for catchments. Soil classifications are useful to create systematic order in the overwhelming quantity of different soils in the world and to extrapolate data available for a given soil type to soils elsewhere with identical classifications. This principle also applies to catchments. However, to be useful, soil classifications have to be based on permanent characteristics as formed by the soil forming factors over often very long periods of time. When defining permanent catchment characteristics, discharge data would therefore appear to be less suitable. But permanent soil characteristics do not necessarily match with characteristics and parameters needed for functional soil characterization focusing, for example, on catchment hydrology. Hydropedology has made contributions towards the required functional characterization of soils as is illustrated for three recent hydrological catchment studies. However, much still needs to be learned about the physical behaviour of anisotropic, heterogeneous soils with varying soil structures during the year and about spatial and temporal variability. The suggestion is made therefore to first focus on improving simulation of catchment hydrology, possibly incorporating hydropedological expertise, before embarking on a catchment classification effort which involves major input of time and involves the risk of distraction. In doing so, we suggest to also define other characteristics for catchment performance than the traditionally measured discharge rates. Such characteristics may well be derived from societal issues being studied, as is illustrated for the Green Water Credits program.

  10. Hydrological relation between two small catchments in central Poland - Zwolenka vs Zagozdzonka rivers

    NASA Astrophysics Data System (ADS)

    Nestorowicz, Anna; Banasik, Kazimierz; Gładecki, Jacek

    2010-05-01

    Hydrological relation between two small catchments in central Poland - Zwolenka vs Zagozdzonka rivers. Key words: long time hydrological data, Nature 2000 network, hydrological relation Since 1992 the European Union is implementing the European Ecological Natura 2000 Network. The main purpose of creation of Natura 2000, is to protect the natural endangered habitats and species of plants and animals across Europe characteristic to 9 regions. In Poland there are only two regions: continental and alpine. Many Nature 2000 areas are in a way connected with water and often covers small not hydrologically investigated catchments and rivers. Since, 2008 the Department of Hydraulic Engineering and Environmental Restoration, Warsaw University of Life Sciences has started a hydrological investigation in Zwoleńka river catchment which valley is a protected Nature 2000 area. One of the most important species in this area is a pond turtle which prefer the wet habitats. There is no precise hydrological data for the Zwoleńka river, however, the other Zagożdżonka river catchment which border on Zwoleńka is investigated since 1963. The main purpose of this investigation is the find the relation between this two river catchment: protected Nature 2000 with no data and carefully investigated Zagożdżonka, with long time hydrological data set.

  11. Coupling catchment hydrology and landscape evolution: Interactive effects on hydrograph and basin shape

    NASA Astrophysics Data System (ADS)

    Vivoni, E. R.; Istanbulluoglu, E.; Bras, R. L.

    2003-12-01

    The catchment hydrologic response to rainfall and the evolution of the river basin network and landscape morphology are closely linked phenomena, albeit active over different temporal scales. While the relation between hydrograph shape and catchment form has long been hypothesized, little is yet understood about the evolution of the basin hydrologic response with catchment age or geomorphic condition. Similarly, the long-term morphologic changes and feedbacks associated with a spatially-variable, evolving runoff response are still unknown. Understanding the complex interaction between basin hydrology and geomorphology was an important pursuit during Michael J. Kirkby's scientific career. In this study, we describe the interactive effects and feedbacks between the basin hydrograph (hydrologic response) and shape (geomorphic response) utilizing two state-of-the-art models: the Channel-Hillslope Integrated Landscape Development (CHILD) and the TIN-based Real-time Integrated Basin Simulator (tRIBS). We first illustrate the changes occurring in the basin hydrograph, variable source area and channel network as the catchment evolves. We then describe how the spatially-explicit hydrologic response from various mechanisms and its associated moisture field directly impacts the erosion and subsequently the basin shape. Quantitative comparisons are then made between a set of interactive and non-interactive simulations for idealized conditions. Our ultimate goal is to highlight the need for coupling distributed simulations of catchment hydrology and geomorphology for investigating the interaction between basin and hydrograph shape.

  12. 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

  13. 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.

  14. 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...

  15. 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...

  16. 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

  17. 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.

  18. Process type identification in torrential catchments

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. 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. PMID:25238398

  20. 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

  1. 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

  2. Modelling herbicide transfers from land to water in the Upper Cherwell catchment UK

    NASA Astrophysics Data System (ADS)

    Whelan, Mick; Tediosi, Alice; Gandolfi, Claudio; Rienzner, Michele; Rushton, Ken; Pullan, Stephanie

    2013-04-01

    Pesticide losses from land to water can present problems for environmental management, particularly in catchments where surface waters are abstracted for drinking water. Here, we describe a model to predict chemical transfers from land to water at the catchment scale. The model was used to describe the behaviour of two herbicides, propyzamide and carbetamide, in the 199 km2 Upper Cherwell catchment, UK, which is used as a municipal water supply. The model operates at two spatial scales: (1) the hillslope scale and (2) the catchment scale. At the hillslope scale pesticide is assumed to diffuse into the majority of the water filled pore volume in a shallow soil layer after application, where it partitions between the dissolved and sorbed phases. A fraction of the dissolved phase pesticide mass in a "mobile" pore water fraction is then displaced by rainfall and is transported to field drains, if present. The hillslope-scale model was tested in a 15.5 ha headwater sub-catchment of the Cherwell, dominated by under-drained heavy clay soil. Significant transfers of both herbicides to the drain network occurred soon after application. Peak concentration coincided with peak drain flow and concentrations then decreased gradually in a quasi-exponential fashion, mirroring the receding hydrograph. Observed carbetamide concentrations were about an order of magnitude higher that those observed for propyzamide due to a combination of a higher application rate and lower KOC. For propyzamide, total observed loss over the study period was estimated to be 1.1% of the applied mass and for carbetamide the loss was estimated to be 8.6%. At the catchment scale, hillslope contributions are integrated using a convolution of the network width function (link frequency distribution), assuming a constant kinematic wave celerity and allowing for the spatial distribution of hillslope contributions from different soil types throughout the network. Two soil types dominate: heavy soils which are

  3. Physical and biological controls on reach to catchment scale nutrient retention and streamwater composition

    NASA Astrophysics Data System (ADS)

    Covino, T. P.; McGlynn, B. L.; Wohl, E.

    2014-12-01

    Physical and biological processes occurring within fluvial networks can have strong influence on catchment scale retention of water and nutrients. Quantifying the physical (i.e., hydrologic exchange) and biological (i.e., nutrient uptake) contributions to total retention and deciphering how they relate to catchment morphology remains a central challenge in the hydrologic and biogeo-sciences. Here we present examples from our research that highlight the interactions between biology, physical hydrology, and geomorphology and how they combine to influence nutrient retention and streamwater compositions. Biological nutrient uptake in streams can have substantial influence on downstream fluxes and induce nutrient transformation along stream networks. Additionally, hydrologic loss of water and associated nutrients from streams to surrounding groundwater systems can greatly elongate water and nutrient retention times. While in-stream nutrient uptake is often associated with hyporheic exchanges that occur at sub-meter scales, these are nested within a larger framework of fluvial exchanges (100s - 1000s of meters). Larger scale exchanges can lead to strong shifts in streamwater composition over relatively short spatial scales (~1km) and are often very pronounced along geomorphic transitions (e.g., mountain to valley) and/or catchment retention zones (e.g., alluvial aquifers, wetlands, lakes). In fact, 50 - 80% of the water in the channel can be exchanged and replaced by different water (i.e., groundwater) along geomorphic transitions/catchment retention zones that are ~1 km in scale. These features can enhance geochemical processing through extended interactions between water, sediment, and nutrients. Accordingly, we suggest that although catchment retention features may be limited in spatial extent (~1km) and frequency they have the capacity to play a disproportionately large role in controlling catchment retention dynamics and setting fluvial network streamwater

  4. 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…

  5. 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

  6. Catchment water storage: Models vs Measurements

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary

    2016-04-01

    Recent years have seen a great deal of progress in development of hydrological models that can simulate both the dynamic streamflow response and the hydrochemical flux response of a catchment. In general terms, streamflow response is driven by water deficit in the catchment, whereas hydrochemical response is driven by water storage. Therefore, models that can simultaneously predict both responses must succeed in representing these two related, but different, quantities. This presentation will consider how much information we can gain from field studies to quantify the joint deficit/storage state of a catchment. In particular, examples from two New Zealand experimental catchments in lowland and high country locations will be used to link typical measurements available with the information required by hydrological - hydrochemical models. I will then use the example catchments to assess how well the structure of a typical hydrological-hydrochemical model is supported by field measurements. In particular, can we quantify catchment storage and link this to flow response? Can we incorporate our knowledge of plant water use into such a model, including timing and depth of water withdrawn by the plant? What can field measurements tell us about spatial variability in hydrological-hydrochemical response and can this be represented in the model? I will conclude by discussing what we can learn from field data about the major challenges ahead in catchment storage modelling.

  7. Doing hydrology backwards in tropical humid catchments

    NASA Astrophysics Data System (ADS)

    Real Rangel, R.; Brena-Naranjo, J. A.; Pedrozo-Acuña, A.

    2015-12-01

    Top-down approaches in hydrology offer the possibility to predict water fluxes at the catchment scale based on the interpretation of the observed hydrological response at the catchment itself. Doing hydrology backwards (inferring precipitation and evapotranspiration rates at the catchment scale from streamflow measurements, see Kirchner (2009)) can be a useful methodology for estimating water fluxes at the catchment and regional scales. Previous studies using this inverse modeling approach have been performed in regions (UK, Switzerland, France, Eastern US) where energy-limited (in winter and early spring) and water-limited conditions (in summer) prevail during a large period of the year. However, such approach has not been tested in regions characterized by a quasi-constant supply of water and energy (e.g. humid tropics). The objective of this work is to infer annual rates of precipitation and evapotranspiration over the last decade in 10 catchments located in Mexico's tropical humid regions. Hourly discharge measurements during recession periods were analyzed and parameters for the nonlinear storage-discharge relationship of each catchment were derived. Results showed large variability in both catchment-scale precipitation and evapotranspiration rates among the selected study sites. Finally, a comparison was done between such estimates and those obtained from remotely-sensed data (TRMM for precipitation and MOD16 for evapotranspiration).

  8. 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.

  9. Sources of sediment in catchments and its eutrophication potential

    NASA Astrophysics Data System (ADS)

    Krasa, Josef; Dostal, Tomas; Bauer, Miroslav; Janotova, Barbora; Rosendorf, Pavel

    2013-04-01

    To help the implementation of Water Framework Directive in the Czech Republic the four-year project was set-up to assess eutrophication factors in endangered catchments. The assessed area covers approximately 40% of the area of the Czech Republic (almost 31 500 km2). The erosion phosphorus loads are modeled by WATEM/SEDEM model adapted for the purpose. For each catchment the sediment transport maps are delivered. Database of 20 477 reservoirs (spatial information taken from DIBAVOD) within CR has been built up during the project and all available information on volumes and flow rates in the reservoirs is collected. From these, 9 890 reservoirs lay in the target area and to estimate the sediment trapping efficiency their volumes and average annual flow rates have to be assessed. The official databases offer less than 10% data coverage so especially for smaller reservoirs the volumes and flow rates have to be derived by analogy using pond area and catchments specific runoff. Brune curves method readjusted by Dendy (1978) is then used for sediment trap efficiency estimation. WATEM/SEDEM model had to be further adapted for modeling phosphorus fluxes within catchments. The ratio of nutrient concentration in eroded sediment to that in the original soil (the enrichment ratio, ER) commonly drops down with raising the soil loss. We used the dependence proposed by Sharply (1995). The soil erodibility factor of WATEM/SEDEM (K-factor) is then replaced by phosphorus erodibility potential. Finally the erosion phosphorus transport is computed getting also phosphorus retention in all reservoirs in target watersheds. In 2012 sediment transport was modeled in all catchments. Assessment of silting of thousands or reservoirs within the stream network of the target catchments is important "side output" of the project Balancing phosphorus sources with attempt to find the importance of erosion for eutrophication is a complicated task. The regular monthly monitoring network in streams and

  10. Geological controls on isotopic signatures of streamflow: results from a nested catchment experiment in Luxembourg (Europe)

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Controls of geology and topography on hydrological metrics, like summer low flow (Grant and Tague, 2004) or dynamic storage (Sayama et al., 2011), have been identified in nested catchment experiments. However, most tracer-based studies on streamflow generation have been carried out in small (10 km2) homogenous catchments (Klaus and McDonnell, 2013). The controlling effects of catchment physiography on how catchments store and release water, and how this eventually controls stream isotope behaviour over a large range of scale are poorly understood. Here, we present results from a nested catchment analysis in the Alzette River basin (Luxembourg, Europe). Our hydro-climatological network consists of 16 recording streamgauges and 21 pluviographs. Catchment areas range from 0.47 to 285 km2, with clean and mixed combinations of distinct geologies ranging from schists to marls, sandstone, dolomite and limestone. Our objective was to identify geological controls on (i) winter runoff ratios, (ii) maximum storage and (iii) isotopic signatures in streamflow. For each catchment we determined average runoff ratios from winter season precipitation-discharge double-mass curves. Maximum catchment storage was based on the dynamic storage change approach of Sayama et al. (2011). Changes in isotopic signatures of streamflow were documented along individual catchment flow duration curves. We found strong correlations between average winter runoff ratios, maximum storage and the prevailing geological settings. Catchments with impermeable bedrock (e.g. marls or schists) were characterised by small storage potential and high average filling ratios. As a consequence, these catchments also exhibited the highest average runoff ratios. In catchments underlain by permeable bedrock (e.g. sandstone), storage potential was significantly higher and runoff ratios were considerably smaller. The isotopic signatures of streamflow showed large differences between catchments. In catchments dominated by

  11. 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.

  12. 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

  13. 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.

  14. Pseudo Paired Catchments Analysis to Assess the Impact of Urbanization on Catchment Hydrology

    NASA Astrophysics Data System (ADS)

    Salavati, B.; Oudin, L.; Furusho, C.; Ribstein, P.

    2014-12-01

    Paired catchments analysis provides a robust approach to assess the impact of land use changes on catchment's hydrological response. This approach is limited by the availability of data for two neighbor catchments with and without land use changes under similar climate conditions. Thus, hydrological modelling approaches are also very popular since they do not depend on data of a reference catchment. In the present study, 70 urbanized and non-urbanized paired catchments were selected in the United States. Unit housing density maps over the 1940-2010 time period were used to reconstruct historic impervious area extents with aproximatly the same resolution as the National Land Cover Database (NLCD) maps. Two approaches were compared to assess the impact of urbanization on catchment-scale hydrology: the classical paired catchments approach using observed flow time series and an alternative paired catchments approach involving hydrological modeling that allows to simulate a virtual control catchment. To this aim, the GR4J model, a conceptual daily 4-parameter hydrological model, was used. The parameters of the model calibrated on the pre urbanization period were used to predict the streamflow that would have occurred in the urban catchment if the urbanization had not taken place. Then, classical statistical methods involving ANCOVA were used to detect the significance and to quantify the change on the hydrological responses due to land use changes. Results show that the two approaches lead to similar conclusions on the impact of urbanization on catchment hydrology. Thus, the modelling approach provides a relevant alternative for case studies where data of reference catchments are not available.

  15. 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

  16. 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

  17. Use of natural tracers to identify spatial and temporal variation in runoff sources in a complex, mountainous mesoscale catchment

    NASA Astrophysics Data System (ADS)

    Soulsby, C.; Rodgers, P.; Petry, J.; Dunn, S.

    2003-04-01

    Natural tracers (18O, Si and alkalinity) were used to assess the spatial and temporal variation in runoff sources within the 230 km^2 Feshie catchment in the Cairngorm Mountains of Scotland as part of the UK Catchment Hydrology And Sustainable Management (CHASM) initiative. The elevation of the mesoscale catchment ranges between 230--1110 m and snowfall comprises, on average, ca. 30% of annual precipitation. Tracer behavior was monitored by routine sampling in gauged, nested subcatchments ranging from 3--90 km^2 over a hydrological year. In addition, extensive surveys sampled the spatial variation in tracer concentrations throughout the catchment river network at low, moderate and high flows at sampling intensities of 1 per 1 km^2. Use of tracer data and GIS-based assessment indicated that catchment characteristics, rather than scale, accounted for the major differences in contributions from contrasting hydrological sources in nested subcatchments. Most notably, geology and the distribution of soil types exerted a strong control on the partitioning of runoff sources and groundwater contributions to flow (which mixing analysis showed range between 25 and 52% of annual flow in different subcatchments). Coverage of organic peat soils and thin montane podzols strongly influenced the storm runoff response of different subcatchments (with average runoff coefficients ranging from 0.75 to 0.4 for different sub-catchments) and dominated stream hydrochemistry at high flows. Despite the dominant influence of catchment characteristics at the sub-catchment scale, as spatial scale increased beyond 100 km^2 within the mesoscale catchment, the influence of significant alluvial aquifers on hydrological response became apparent. Neverthless, at scales >3 km^2, preliminary analysis of weekly 18O data indicated that mean residence times are similar, though it is reasonable to expect that residence time distributions would vary if high resolution tracer samples (ie daily or sub

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Williams, K.; Locke, W. W.

    2009-12-01

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

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Kollongei, Kipkemboi J.; Lorentz, Simon A.

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

  2. Towards catchment classification by means of environmental tracers and landscape analysis: The Attert catchment in Luxembourg

    NASA Astrophysics Data System (ADS)

    Wrede, S.; Pfister, L.; Krein, A.; Fenicia, F.; Bogaard, T. A.; Uhlenbrook, S.; Savenije, H. H. G.

    2010-05-01

    Until recently hydrological research has been mainly focusing on detailed investigations at small spatial scales, resulting in a set of more and more complex physically-based and spatially distributed hydrologic models. While much of the research effort today is targeted to advance these hydrological model predictions at the catchment scale, shortcomings remain to adequately capture the dominating hydrological processes across a range of scales that translate into the rainfall-runoff response of a catchment. Thus, studies addressing the fundamental relations between catchment structure and function are urgently needed, as they help catchment classification by advancing our knowledge about suitable catchment signatures and controls at different spatial and temporal scales. In our study in the nested Attert catchment in the Grand-Duchy of Luxembourg (Europe) we investigate how environmental tracer dynamics, hydrological response behavior and landscape analysis can help to identify such dominating controls on runoff generation across multiple scales. Techniques to characterize landscape structure and hydrological processes are complementary applied to identify scales in which shifts of the dominant hydrological processes occur. These dominating controls in turn provide a more integrated perspective of catchment structure and functioning that can be used for catchment classification based on functional response.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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. PMID:26801154

  8. 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.

  9. Hydropedological insights when considering catchment classification

    NASA Astrophysics Data System (ADS)

    Bouma, J.; Droogers, P.; Sonneveld, M. P. W.; Ritsema, C. J.; Hunink, J. E.; Immerzeel, W. W.; Kauffman, S.

    2011-02-01

    Soil classification systems are analysed in relation to the functioning and characterisation of catchments. Soil classifications are useful to create systematic order in the overwhelming quantity of different soils in the world and to extrapolate data available for a given soil type to soils elsewhere with identical classifications. However, such classifications are based on permanent characteristics as formed by the soil forming factors over often very long periods of time and this does not necessarily match with characteristics and parameters needed for functional soil characterization focusing, for example, on catchment hydrology. Hydropedology has made contributions towards functional characterization of soils as is illustrated for recent hydrological catchment studies. However, much still needs to be learned about the physical behaviour of anisotropic, heterogeneous field soils with varying soil structures during the year and the suggestion is made to first focus on improving simulation of catchment hydrology, incorporating hydropedological expertise, before embarking on a classification effort which involves major input of time and involves the risk of distraction. In doing so, we advise to also define other characteristics for catchment performance than the traditionally measured discharge rates.

  10. Flood Nowcasting With Linear Catchment Models, Radar and Kalman Filters

    NASA Astrophysics Data System (ADS)

    Pegram, Geoff; Sinclair, Scott

    A pilot study using real time rainfall data as input to a parsimonious linear distributed flood forecasting model is presented. The aim of the study is to deliver an operational system capable of producing flood forecasts, in real time, for the Mgeni and Mlazi catchments near the city of Durban in South Africa. The forecasts can be made at time steps which are of the order of a fraction of the catchment response time. To this end, the model is formulated in Finite Difference form in an equation similar to an Auto Regressive Moving Average (ARMA) model; it is this formulation which provides the required computational efficiency. The ARMA equation is a discretely coincident form of the State-Space equations that govern the response of an arrangement of linear reservoirs. This results in a functional relationship between the reservoir response con- stants and the ARMA coefficients, which guarantees stationarity of the ARMA model. Input to the model is a combined "Best Estimate" spatial rainfall field, derived from a combination of weather RADAR and Satellite rainfield estimates with point rain- fall given by a network of telemetering raingauges. Several strategies are employed to overcome the uncertainties associated with forecasting. Principle among these are the use of optimal (double Kalman) filtering techniques to update the model states and parameters in response to current streamflow observations and the application of short term forecasting techniques to provide future estimates of the rainfield as input to the model.

  11. Evidence of the impact of urbanization on the hydrological regime of a medium-sized periurban catchment in France

    NASA Astrophysics Data System (ADS)

    Braud, I.; Breil, P.; Thollet, F.; Lagouy, M.; Branger, F.; Jacqueminet, C.; Kermadi, S.; Michel, K.

    2013-04-01

    SummaryIn this paper we explore several indicators to evidence the impact of land use change, and particularly of urbanization/artificialization on discharge series of periurban catchments. A first set of indicators is derived from the literature and describes the monthly and annual hydrological regime, low flows and high flows, and flow components. Statistical tests are also applied to assess the existence of trends/ruptures on the longest time series. In addition, new indicators, especially built to show the impact of sewer overflow devices (SODs) and infiltration into sewer networks are proposed. The method is applied to the Yzeron (150 km2) catchment, located close to Lyon city (France) where various discharge gauges with a variable time step are available on sub-catchments ranging from a few to 130 km2 (some of them nested), with a large variety of land uses (forest, agricultural land, artificialized areas). In addition, discharge is also measured in a SOD and a combined sewer network so that the relevance of the new proposed indicators can be assessed. In the largest sub-catchments, the results show a decrease of specific discharge from upstream to downstream corresponding to an increase of artificialized areas, except for high flows. When a SOD is present, the specific discharge is increased for frequencies larger than 50%, and the frequency of zero daily discharge is decreased. Waste water can be the only source of water in autumn month in a 4.1 km2 sub-catchment. Base flow is also decreased for the most urbanized catchments. Our results confirm the impact of SODs on the modification of the flood regime, with an increase of frequent floods, but a marginal impact on the largest floods, mainly governed by saturation of the rural parts of the catchments. The decomposition of the sewer discharge shows that, on an annual basis, infiltration in the sewer network accounts for 30% of the total discharge and runoff due to rainwater to about 40% (the remaining being

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  19. 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.

  20. 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

  1. Development of regionalisation procedures using a multi-model approach for flow simulation in an ungauged catchment

    NASA Astrophysics Data System (ADS)

    Goswami, M.; O'Connor, K. M.; Bhattarai, K. P.

    2007-02-01

    SummaryFlow simulation in ungauged catchments is presently regarded as one of the most challenging tasks in surface water hydrology. Many of the ungauged catchments are located in the headwaters of rivers in mountainous regions of the world having enormous potential for sustainable water resource development. However, due to inaccessibility, rugged and inhospitable terrain, and historical lack of foresight concerning the need to have these headwaters adequately gauged, their potential is not readily realizable. Many downstream sites also suffer from non-availability of site-specific data as even in countries having extensive networks of gauged stations data may not be available at sites where these are most needed. As predictive tools for water resources, water quality, natural hazard mitigation and water availability assessment are generally data-driven, the lack of adequate hydrometric records poses difficult problems for planners, engineers, managers, and stake-holders alike. In this study, a methodology is developed for flow simulation in ungauged catchments using a regionalisation and multi-model approach involving a suite of rainfall-runoff models and combination techniques. Daily observed hydrometeorological data for 12 French catchments are used for illustrating the procedures. Following a preliminary investigation of the regional homogeneity of that group of catchments, three regional flow simulation techniques are applied. Although all 12 catchments are gauged, initially each catchment is successively considered as being ungauged for the purpose of flow simulation in that catchment, their actual discharges being subsequently used for evaluating the performance of the flow estimation procedures for the catchment. The Nash-Sutcliffe efficiency index ( R2) is used for assessing and ranking the relative performances of the regionalisation-model couples to identify the most appropriate couple for the region. The final step of applying that couple to a truly

  2. 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.

  3. Paleofluvial landscape inheritance for Jakobshavn Isbræ catchment, Greenland

    NASA Astrophysics Data System (ADS)

    Cooper, M. A.; Michaelides, K.; Siegert, M. J.; Bamber, J. L.

    2016-06-01

    Subglacial topography exerts strong controls on glacier dynamics, influencing the orientation and velocity of ice flow, as well as modulating the distribution of basal waters and sediment. Bed geometry can also provide a long-term record of geomorphic processes, allowing insight into landscape evolution, the origin of which may predate ice sheet inception. Here we present evidence from ice-penetrating radar data for a large dendritic drainage network, radiating inland from Jakobshavn Isbræ, Greenland's largest outlet glacier. The size of the drainage basin is ˜450,000 km2 and accounts for about 20% of the total land area of Greenland. Topographic and basin morphometric analyses of an isostatically uplifted (ice-free) bedrock topography suggests that this catchment predates ice sheet initiation and has likely been instrumental in controlling the location and form of the Jakobshavn ice stream, and ice flow from the deep interior to the margin, now and over several glacial cycles.

  4. 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

  5. Modeling daily streamflow at ungauged catchments: What information is necessary?

    NASA Astrophysics Data System (ADS)

    Patil, S.; Stieglitz, M.

    2011-12-01

    Streamflow modeling at ungauged catchments involves transfer of information (viz., model structure and parameters) from gauged to ungauged catchments that are judged to be hydrologically similar. In this study, we focus on identifying: (1) what constitutes the critical information that needs to be transferred among hydrologically similar catchments to achieve good predictability using models at ungauged sites, and (2) which is the best approach for transferring this information from gauged to ungauged catchments. We develop a simple hydrologic model with minimal calibration requirement and implement it over 756 catchments located across the continental United States. The model computes water balance at a daily time-step and conceptualizes subsurface runoff through a storage-dependent exponential decline in saturated hydraulic conductivity. Snow accumulation and melt are modeled using the thermal degree-day concept. The calibrated model performs better in humid runoff-dominated regions than in the drier evapotranspiration-dominated regions. Results show that within a region, transfer of hydrograph recession information alone is sufficient for reliable streamflow predictions at ungauged catchments. Information transfer from spatially proximate gauged catchments provides better streamflow predictability at ungauged catchments than transfer from catchments identified as physically similar. When considering spatially proximate catchments, information transfer from multiple donor catchments is preferable to transfer from a single donor catchment.

  6. The artifcial catchment Chicken Creek as a tool to study initial ecosystem development

    NASA Astrophysics Data System (ADS)

    Schaaf, W.; Elmer, M.; Fischer, A.; Gerwin, W.; Nenov, R.

    2011-12-01

    areas with evolving terrestrial or aquatic characteristics and from a very episodic to a more permanent stream network and discharge, together with the observed vegetation dynamics increased site diversity and heterogeneity with respect to water and nutrient availability and transformation processes compared to the more homogenous conditions at point zero. We expect that these more permanent structures and patterns established after five years will greatly influence the future development of the catchment with respect to e.g. input and accumulation of soil organic matter, nitrogen input and availability by symbiotic microbial N-fixation, development of root systems and soil food webs, weathering and soil formation, element cycling, and the water and element budget at the catchment scale.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  8. 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.

  9. Global investigation of vegetation impact on mean annual catchment evapotranspiration

    NASA Astrophysics Data System (ADS)

    Peel, Murray C.; McMahon, Thomas A.; Finlayson, Brian L.

    2010-05-01

    Historically, relationships between catchment vegetation type, evapotranspiration and runoff have been assessed primarily through paired catchment studies. The literature contains results from over 200 of these studies from around the world but two factors limit the applicability of the results to the wider domain. Firstly, catchment areas are generally small (<10 km2). Secondly, the range of climate types is narrow, with temperate (Köppen C) and cold (Köppen D) climate types in the majority. Here we present results from a global assessment of the impact of vegetation type on mean annual catchment evapotranspiration for a large, spatially and climatically diverse dataset of 699 catchments. This assessment is based on analysis of areal precipitation, temperature, runoff, and land cover information from each catchment, which differs from the paired catchment methodology where streamflow responses to a controlled land cover change are assessed. When catchments are grouped by vegetation type, any evidence of differing vegetation impact on actual evapotranspiration will be observed through differences in mean annual actual evapotranspiration, defined as precipitation minus runoff. Stratifying catchments by climate type was observed to be important when assessing the vegetation impact on evapotranspiration. Tropical and temperate forested catchments had significantly higher median evapotranspiration (~170mm and ~130mm, respectively) than non-forested catchments. Cold forested catchments unexpectedly had significantly lower median evapotranspiration (~90mm) than non-forested catchments. No significant difference in median evapotranspiration was found between temperate evergreen and deciduous forested catchments, though sample sizes were small. Temperate evergreen needleleaf forested catchments had significantly higher median evapotranspiration than evergreen broadleaf forested catchments, though again sample sizes were small. The significant difference in median

  10. Hydrologic predictions on ungauged catchments using deterministic distributed modelling system

    NASA Astrophysics Data System (ADS)

    Tachecí, Pavel; Kimlová, Martina

    2010-05-01

    simulation. Back-calculation of initial conditions using regular observation network data is applied to minimize errors of water balance. Scaled values of simulated deficit of water content in unsaturated zone, aggregated over user-defined areas, were chosen as flash-flood danger indicator. User - defined templates for presentation of results are available. The advantage of this approach sustains in a fact, that it uses three different types of input data. Further on, it may give results for user-defined areas, which are not necessarily connected to on-line flow gauging station profiles. This means, that it is capable to give flash-flood danger maps also for upper catchments and small tributaries, which are not included in the network of main warning profiles.

  11. Geomorphic connectivity within abandoned small catchments (Stołowe Mts, SW Poland)

    NASA Astrophysics Data System (ADS)

    Latocha, Agnieszka

    2014-05-01

    Studying 5 small catchments (0.6-2.7 km2) located in the central part of the Stołowe Mountains (SW Poland), which are partly or totally abandoned, has revealed the substantial changes of connectivity within the catchments. Field investigation (geomorphic mapping, morphometric analyses) and GIS based analyses of historical data show that slope-channel coupling is much less efficient than in the past, mainly due to the decrease of unpaved road network, especially roads linked directly with streams. Also land-use change with considerable loss of arable land does not support erosion from slopes. The general direction of geomorphic change due to depopulation and lack of maintenance of anthropogenic features tends towards higher stability and lower efficiency of morphological processes, connected with a sustained decrease in slope-channel coupling. This tendency is evidenced by relict landscape features (e.g. road gullies, abandoned roads) formed in the period of more intensive land use, for which higher dynamics of the morphogenetic system may be inferred. The evidence of contemporary erosion and mineral material transport is very local and spatially limited to a few roads which are still in use. Sediment transfer is additionally slowed down by the presence of numerous anthropogenic barriers within slope and valley-floor domains. Even though their total impact may seem only local and negligible at the catchment scale, their contribution to increase the diversity of morphological processes is significant. Especially the neglect of hydrotechnical constructions enhances trapping of material within the catchments.

  12. Feedbacks between structures and processes during initial ecosystem development in an artificial catchment

    NASA Astrophysics Data System (ADS)

    Schaaf, Wolfgang; Elemer, Michael; Gerwin, Werner; Fischer, Anton; Zaplata, Markus; Neneov, Rossen

    2013-04-01

    We studied the role of strutures and processes and their feedbacks during initial ecosystem development in the artificial catchment Chicken Creek. During the first seven years, considerable changes within the catchment were observed. Both internal and external factors could be identified as driving forces for the formation of structures and patterns in the artificial catchment. Initial structures formed by the construction process and initial substrate characteristics were decisive for the distribution and flow of water. External factors like episodic events triggered erosion and dissection during this initial phase, promoted by the low vegetation cover and the unconsolidated sandy substrate. The transformation of the initial geo-system into areas with evolving terrestrial or aquatic characteristics and from a very episodic to a more permanent stream network and discharge, together with the observed vegetation dynamics increased site diversity and heterogeneity with respect to water and nutrient availability and transformation processes compared to the more homogenous conditions at point zero. The processes and feedback mechanisms in the initial development of a new landscape may deviate in rates, intensity and dominance from those known from mature ecosystems. It is therefore crucial to understand these early phases of ecosystem development and to disentangle the increasingly complex interactions between the evolving terrestrial and aquatic, biotic and abiotic compartments of the system. Artificially created catchments could be a suitable tool to study these initial developments at the landscape scale under known, designed and defined boundary conditions.

  13. 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.

  14. Morphotectonic interpretation of the Makuyuni catchment in Northern Tanzania using DEM and SAR data

    NASA Astrophysics Data System (ADS)

    Flores-Prieto, Elio; Quénéhervé, Geraldine; Bachofer, Felix; Shahzad, Faisal; Maerker, Michael

    2015-11-01

    Landscapes in the East African Rift System are formed by complex effects of the active continental extension zone. These effects are caused by the Somalian micro-plate's eastward drift away from the Nubian plate, as well as by volcanic, erosional and depositional processes. Tectonic processes in this region have significantly contributed to the formation of the current drainage systems and landforms. This study focuses on the morphotectonics of the Makuyuni catchment with an analysis of topography, drainage networks, stream longitudinal profiles and lineaments. This analysis reveals a morphostructural control with an N-S trend for the uplifted Masai Block, as well as tectonic deformation in the Makuyuni catchment area (NE of Lake Manyara). Whereas basin asymmetry analysis shows basin tilting associated with active faulting and uplifting near the Essimingor volcanic cone, in this catchment the steepness and concavity indices, coupled with lineaments obtained from interpretations of Synthetic Aperture Radar satellite scenes, show an uplifting along micro-faults. Hypsometry curves reveal that subcatchments on the right side of the Makuyuni River are in a mature equilibrium phase, whereas those at the left side are in a younger stage of maturity. An investigation of base level and statistical moments of the hypsometric curves provides evidences for the spatial distribution of gully erosion phenomena. Such erosion processes are due to tectonic deformation in the northern parts of the Makuyuni catchment. These results of regional tectonic instability suggest that tectonic processes are a significant factor for the current landscape evolution in the Lake Manyara basin.

  15. 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.

  16. 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.

  17. Identifying sediment sources in a gullied catchment using natural and anthropogenic radioactivity

    NASA Astrophysics Data System (ADS)

    Olley, J. M.; Murray, A. S.; MacKenzie, D. H.; Edwards, K.

    1993-04-01

    The ratio of the lithogenic nuclides 226Ra and 232Th indicates that the major source of sediment in transport in a gullied catchment, located in the head waters of Whiteheads Creek, New South Wales, Australia, is the gully itself. This observation is supported by 7Be and 137Cs concentrations which indicate that the sediment is derived from erosion of either gully floor or gully wall material. While subcatchment 7Be and 137Cs data show sheet, rill, and gully erosion are occurring in the upstream catchments, sediment from these sources is either being trapped before entering the gully, or the volume of sediment is small compared to that derived from the gully itself. The differences in the 226Ra to 232Th ratio between the suspended solids collected on the rising stage and samples of sediment deposited during the falling stage at the outlet of the catchment, indicate a change in the source of sediment during storm events. The results presented here demonstrate the applicability of radionuclide tracers in providing quantitative estimates of the relative contributions of individual catchments to the sediment moving within a drainage network, and in determining whether or not the sediments are mainly derived from subsoil or topsoil sources.

  18. Characterizing long-term hydrologic-response and sediment-transport for the R-5 catchment.

    PubMed

    Heppner, Christopher S; Loague, Keith

    2008-01-01

    Recently there have been several calls to establish long-term data collection networks to monitor near-surface hydrologic response and landscape evolution. The focus of this paper is a long-term dataset from the International Hydrologic Decade (1965-1974). The small upland catchment, known as R-5, located near Chickasha, Olahoma, has been the subject of considerable attention within the event-based hydrologic modeling community for more than 30 yr. Here, for the first time, 8 yr of continuous near-surface hydrologic-response and sediment-transport data are analyzed to show trends in the catchment's long-term behavior. The datasets include precipitation, temperature, solar radiation, soil-water content, infiltration, water discharge, and sediment discharge. Potential and actual evapotranspiration rates were estimated and used to calculate an average annual water balance for the catchment. Findings include, for example, that rainfall intensity rarely exceeds the threshold for Horton-type runoff, soil-water content is both spatially and temporally variable, and the water and sediment discharge rates are positively correlated. The R-5 data provide a unique opportunity to test (and refine) process-based models of continuous hydrologic response and sediment transport at the catchment scale for applications in the emerging fields of hydroecology and hydrogeomorphology. PMID:18948471

  19. Co-evolution of volcanic catchments in Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Troch, P. A.

    2015-09-01

    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 co-evolution 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) 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 significant correlation between drainage density and baseflow index with age, but not with climate. The age of the catchments was also significantly related to intra-annual flow variability. Younger catchments tend to have lower peak flows and higher low flows, while older catchments exhibit more flashy runoff. The decrease of baseflow with catchment age confirms previous studies that hypothesized that in volcanic landscapes the major flow pathways have changed over time, from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in similar volcanic catchments but of significant younger age than the ones explored here. In these younger catchments, an increase in drainage density with age was observed, and it was hypothesized that this was because of more landscape incision due to increasing near-surface lateral flow paths in more mature catchments. Our results suggests two hypotheses on the evolution of drainage density in matured catchments. One is that as catchments further evolve

  20. Measuring winter precipitation in a mountain catchment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measuring winter precipitation (principally snowfall) in a mountain catchment is difficult. The magnitude of gauge under catch is affected by variable density during deposition, wind speed and direction, and site conditions such as vegetation and topography. Though numerous studies have been condu...

  1. 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...

  2. Geomorphic histories for river and catchment management.

    PubMed

    Wasson, R J

    2012-05-13

    River and catchment management usually proceeds from the identification of an undesirable state (e.g. pollution, sedimentation, excessive water extraction, dams, invasion by exotic species) to a strategy for reaching a desirable state described as a target. Desirable states are usually determined from community values, economic assessments and ecosystem functions, or a combination of these. Where a catchment is highly disturbed, the target is usually not a natural state, as that cannot be achieved while maintaining human uses, and a history is needed to document the disturbance, understand its cause and define the 'existence space', that is, the range of natural states that have occurred in the past. Where a catchment is less disturbed, a former natural state could provide a target for management. But which of the many natural (equilibrium) states that have occurred in the past should be the target? The paper reviews what is known of the quantitative difference between pre- and post-disturbance states, searches for the presence or otherwise of equilibrium and comments on the utility of this information for catchment management. The focus is on erosion and sediment transport. PMID:22474683

  3. Catchment management and the Great Barrier Reef.

    PubMed

    Brodie, J; Christie, C; Devlin, M; Haynes, D; Morris, S; Ramsay, M; Waterhouse, J; Yorkston, H

    2001-01-01

    Pollution of coastal regions of the Great Barrier Reef is dominated by runoff from the adjacent catchment. Catchment land-use is dominated by beef grazing and cropping, largely sugarcane cultivation, with relatively minor urban development. Runoff of sediment, nutrients and pesticides is increasing and for nitrogen is now four times the natural amount discharged 150 years ago. Significant effects and potential threats are now evident on inshore reefs, seagrasses and marine animals. There is no effective legislation or processes in place to manage agricultural pollution. The Great Barrier Reef Marine Park Act does not provide effective jurisdiction on the catchment. Queensland legislation relies on voluntary codes and there is no assessment of the effectiveness of the codes. Integrated catchment management strategies, also voluntary, provide some positive outcomes but are of limited success. Pollutant loads are predicted to continue to increase and it is unlikely that current management regimes will prevent this. New mechanisms to prevent continued degradation of inshore ecosystems of the Great Barrier Reef World Heritage Area are urgently needed. PMID:11419129

  4. 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

  5. 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.

  6. Predicting nutrient responses to mitigation at catchment to national scale: the UK research platform (Invited)

    NASA Astrophysics Data System (ADS)

    Johnes, P.

    2013-12-01

    Nutrient enrichment of waters from land-based and atmospheric sources presents a significant management challenge, requiring effective stakeholder engagement and policy development, properly underpinned by robust scientific evidence. The challenge is complex, raising significant questions about the specific sources, apportionment and pathways that determine nutrient enrichment and the key priorities for effective management and policy intervention. This paper presents outputs from 4 major UK research programmes: the Defra Demonstration Test Catchments programme (DTC), the Environment Agency's Catchment Sensitive Farming monitoring and evaluation programme (CSF), Natural Resources Wales Welsh Catchment Initiative (WCI) and the NERC Environmental Virtual Observatory programme (EVOp). Funded to meet this challenge, they are delivering new understanding of the rates and sources of pollutant fluxes from land to water, their impacts on ecosystem goods and services, and likely trends under future climate and land use change from field to national scale. DTC, a 12m investment by the UK Government, has set up long-term, high resolution research platforms equipped with novel telemetered sensor networks to monitor stream ecosystem responses to on-farm mitigation measures at a representative scale for catchment management. Ecosystem structural and functional responses and bulk hydrochemistry are also being monitored using standard protocols. CSF has set up long-term, enhanced monitoring in 8 priority catchments, with monthly monitoring in a further 72 English catchments and 6 Welsh priority catchments, to identify shifts in pollutant flux to waters resulting from mitigation measures in priority areas and farming sectors. CSF and WCI have contributed to >50 million of targeted farm improvements to date, representing a significant shift in farming practice. Each programme has generated detailed evidence on stream ecosystem responses to targeted mitigation. However, to provide

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  9. Controls on Nitrate Spatial Variability in Paine Run Catchment of Shenandoah National Park

    NASA Astrophysics Data System (ADS)

    Ingram, S. M.; Scanlon, T. M.

    2007-12-01

    This research examines the catchment-scale controls on in-stream nitrate concentrations by (1) quantifying nitrate spatial variability in a headwater catchment and (2) determining the biophysical processes underlying this variability. The Shenandoah Watershed Study (SWAS) established thirty-eight stream sampling sites in the Paine Run catchment to collect field data on stream chemistry, discharge and transient storage. An evaluation of SWAS data at these sites from the early 1990s to 2007 reveals spatial and temporal variability in nitrate concentrations following the gypsy moth defoliation. We observed high in-stream nitrate concentrations with elevation and an apparent dilution at lower elevations. Main topographic descriptors related to the spatial distribution of nitrate, elevation and contributing area, are associated with differing biophysical factors such as soil residence time, bacterial denitrification, vegetation and mineralization. Previous studies have demonstrated that the physical properties of hyporheic zones can strongly influence denitrification rates. We examined this in the Paine Run catchment with tracer tests to evaluate dilution effects and predict stream outflow and inflow from hyporheic zones responsible for denitrification. We then looked for biophysical processes responsible for higher nitrate levels at higher elevation by using the OTIS model for transient storage to evaluate hyporhiec zones in Paine Run. We also established a method to evaluate soil parameters for depth and permeability. By identifying the controls on nitrate inputs, transport and denitrification, we isolated a set of criteria applied to a quantitative model for nitrate spatial variability. This research has important implications for defining nutrient availability both within the stream network and at the outlet of forested headwater catchments.

  10. 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

  11. Inverse distributed hydrological modelling of alpine catchments

    NASA Astrophysics Data System (ADS)

    Kunstmann, H.; Krause, J.; Mayr, S.

    2005-12-01

    Even in physically based distributed hydrological models, various remaining parameters must be estimated for each sub-catchment. This can involve tremendous effort, especially when the number of sub-catchments is large and the applied hydrological model is computationally expensive. Automatic parameter estimation tools can significantly facilitate the calibration process. Hence, we combined the nonlinear parameter estimation tool PEST with the distributed hydrological model WaSiM. PEST is based on the Gauss-Marquardt-Levenberg method, a gradient-based nonlinear parameter estimation algorithm. WaSiM is a fully distributed hydrological model using physically based algorithms for most of the process descriptions. WaSiM was applied to the alpine/prealpine Ammer River catchment (southern Germany, 710 km2) in a 100×100 m2 horizontal resolution. The catchment is heterogeneous in terms of geology, pedology and land use and shows a complex orography (the difference of elevation is around 1600 m). Using the developed PEST-WaSiM interface, the hydrological model was calibrated by comparing simulated and observed runoff at eight gauges for the hydrologic year 1997 and validated for the hydrologic year 1993. For each sub-catchment four parameters had to be calibrated: the recession constants of direct runoff and interflow, the drainage density, and the hydraulic conductivity of the uppermost aquifer. Additionally, five snowmelt specific parameters were adjusted for the entire catchment. Altogether, 37 parameters had to be calibrated. Additional a priori information (e.g. from flood hydrograph analysis) narrowed the parameter space of the solutions and improved the non-uniqueness of the fitted values. A reasonable quality of fit was achieved. Discrepancies between modelled and observed runoff were also due to the small number of meteorological stations and corresponding interpolation artefacts in the orographically complex terrain. A detailed covariance analysis was performed

  12. Inverse distributed hydrological modelling of Alpine catchments

    NASA Astrophysics Data System (ADS)

    Kunstmann, H.; Krause, J.; Mayr, S.

    2006-06-01

    Even in physically based distributed hydrological models, various remaining parameters must be estimated for each sub-catchment. This can involve tremendous effort, especially when the number of sub-catchments is large and the applied hydrological model is computationally expensive. Automatic parameter estimation tools can significantly facilitate the calibration process. Hence, we combined the nonlinear parameter estimation tool PEST with the distributed hydrological model WaSiM. PEST is based on the Gauss-Marquardt-Levenberg method, a gradient-based nonlinear parameter estimation algorithm. WaSiM is a fully distributed hydrological model using physically based algorithms for most of the process descriptions. WaSiM was applied to the alpine/prealpine Ammer River catchment (southern Germany, 710 km2 in a 100×100 m2 horizontal resolution. The catchment is heterogeneous in terms of geology, pedology and land use and shows a complex orography (the difference of elevation is around 1600 m). Using the developed PEST-WaSiM interface, the hydrological model was calibrated by comparing simulated and observed runoff at eight gauges for the hydrologic year 1997 and validated for the hydrologic year 1993. For each sub-catchment four parameters had to be calibrated: the recession constants of direct runoff and interflow, the drainage density, and the hydraulic conductivity of the uppermost aquifer. Additionally, five snowmelt specific parameters were adjusted for the entire catchment. Altogether, 37 parameters had to be calibrated. Additional a priori information (e.g. from flood hydrograph analysis) narrowed the parameter space of the solutions and improved the non-uniqueness of the fitted values. A reasonable quality of fit was achieved. Discrepancies between modelled and observed runoff were also due to the small number of meteorological stations and corresponding interpolation artefacts in the orographically complex terrain. Application of a 2-dimensional numerical

  13. Establishing a connection between hydrologic model parameters and physical catchment signatures for improved hierarchical Bayesian modeling in ungauged catchments

    NASA Astrophysics Data System (ADS)

    Marshall, L. A.; Weber, K.; Smith, T. J.; Greenwood, M. C.; Sharma, A.

    2012-12-01

    In an effort to improve hydrologic analysis in areas with limited data, hydrologists often seek to link catchments where little to no data collection occurs to catchments that are gauged. Various metrics and methods have been proposed to identify such relationships, in the hope that "surrogate" catchments might provide information for those catchments that are hydrologically similar. In this study we present a statistical analysis of over 150 catchments located in southeast Australia to examine the relationship between a hydrological model and certain catchment metrics. A conceptual rainfall-runoff model is optimized for each of the catchments and hierarchical clustering is performed to link catchments based on their calibrated model parameters. Clustering has been used in recent hydrologic studies but catchments are often clustered based on physical characteristics alone. Usually there is little evidence to suggest that such "surrogate" data approaches provide sufficiently similar model predictions. Beginning with model parameters and working backwards, we hope to establish if there is a relationship between the model parameters and physical characteristics for improved model predictions in the ungauged catchment. To analyze relationships, permutational multivariate analysis of variance tests are used that suggest which hydrologic metrics are most appropriate for discriminating between calibrated catchment clusters. Additional analysis is performed to determine which cluster pairs show significant differences for various metrics. We further examine the extent to which these results may be insightful for a hierarchical Bayesian modeling approach that is aimed at generating model predictions at an ungauged site. The method, known as Bayes Empirical Bayes (BEB) works to pool information from similar catchments to generate informed probability distributions for each model parameter at a data-limited catchment of interest. We demonstrate the effect of selecting

  14. Implementing a Catchment-Based, National-Scale Land Surface and River Routing Model

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Famiglietti, J. S.; Kim, H.

    2012-12-01

    In this study we characterize how accurately we can estimate river discharge, river depth and inundation extent using a catchment-based hydrological and routing modeling system (CHARMS) with an explicit representation of the river network. Here we present a national- scale implementation of CHARMS that includes an explicit representation of the river network upscaled from the NHDPlus dataset. HUC8 (Hydrologic Unit Code) is chosen as the average catchment size (~3900 km2), and the main river channel in each catchment is extracted using the Strahler Stream Oder from NHDPlus. We also derive empirical relationships between channel dimensions and drainage area to describe the river cross- sectional profile for several large regions of the country. The modeled daily streamflow shows reasonable agreement with gage observations. River depth and floodplain extent associated with each river reach are also explicitly simulated. Results have implications for capturing the seasonal-to-interannual dynamics of surface water in climate models, and for assimilation of surface water altimetry, e.g. from the upcoming NASA SWOT mission.

  15. Application of continuum- and hybrid models in karst spring catchments

    NASA Astrophysics Data System (ADS)

    Rehrl, Christoph; Birk, Steffen

    2010-05-01

    Flow in karst aquifers is concentrated along highly permeable solution conduits embedded in the much less permeable fissured system of the surrounding rock. This complex and heterogeneous flow regime can be conceptualized as dual flow systems composed of slow, laminar flow in the fractured porous matrix as opposed to rapid, often turbulent flow in solution conduits. Flow in the fractured porous rock can be treated as a continuous flow field (continuum model), whereas flow in the conduit system is spatially localized and can be modelled by a discrete pipe network model. Hybrid models couple both flow systems and have frequently been employed in basic research, e.g., to simulate and analyse the mechanism of speleogenesis. In many practical applications, however, continuum models are employed. In these models the two flow components are lumped together and the conduits are represented by highly permeable cells (smeared conduit approach). Standard groundwater models imply that conduit flow is represented by a Darcian approach, thus ignoring potential effects of turbulent flow. On this account the USGS has recently released a MODFLOW-2005 Conduit Flow Process (CFP), which makes it possible to account for turbulent flow in the continuum approach (CFP mode 2). Additionally a discrete pipe network model can be coupled to MODFLOW. This hybrid model (CFP mode 1) employs the Darcy-Weisbach equation to represent turbulent flow in the karst conduits. In this work, it is attempted to simulate the discharge hydrographs of a hypothetical karst spring catchment in which conduit systems are embedded in fissured porous rock using both the single-continuum approach (CFP mode 2) and the hybrid model (CFP mode 1). This study shows that the hydraulic response of the spring signal is influenced by the flow conditions in the conduit, i.e. the shape of the spring hydrograph predicted by a model that accounts for turbulent flow differs from that obtained with a laminar flow model. This

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  20. Downward approach at the catchment scale or at the catchment set scale?

    NASA Astrophysics Data System (ADS)

    Perrin, C.; Andréassian, V.; Le Moine, N.

    2009-04-01

    The downward approach that learns from observations the main features of the catchment hydrological response has long been recognized as a way to develop hydrological models for the catchment scale (Klemes, 1983). In this approach, a link is made between rainfall inputs and flow outputs using the mathematical tools found the most efficient to reproduce catchment behaviour. This approach received recently more attention, as some limitations of the upward approach were identified (Sivapalan et al., 2003). However model structures developed with this downward approach at the catchment scale are often difficult to generalize, i.e. difficult to transpose to other catchments. Indeed they are often over-adapted to the specific features of the catchment on which they were developed. Generalization is a major problem in current hydrological modelling (Sivakumar, 2008). This is potentially a major drawback for the application of such models to the case of ungauged catchments. We argue that a better way to develop the structure of hydrological models following a downward approach is to place model development at the level of large set of catchments and not only at the level of a single catchment. This way of developing models will force them to be general, i.e. more transposable in space. They will capture the essential features of the rainfall-runoff transformation common between catchments. This way of developing models also gives the opportunity to analyse the spatial patterns of model failures, therefore providing more robust sources of explanations and more convincing ways to improve models. We do not believe that we could develop a single model that fit all conditions, but models developed with this approach are likely to be better starting points to get general models. Then we have to find ways to make them more appropriate to specific conditions without losing their generality. We will illustrate the advantages (and possible limitations) of this approach using

  1. Catchment Engineering: A New Paradigm in Water Management

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Here, a catchment engineering approach seeks to describe catchment 'function' (or role) as the principal driver for evaluating how it should be managed in the future. Catchment engineering does not seek to re-establish a natural system but seeks to work with natural processes in order to engineer landscapes so that multiple benefits accrue. This approach involves quantifying and assessing catchment change and impacts but 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, namely the general public and policy makers. This inclusive concept under a catchment 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 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. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Catchment engineering is a concept that relies on all relevant parties within a catchment to take responsibility for the water quantity and quality that arises from the catchment. Further, any holistic solution requires a bottom up, problem solving

  2. Co-evolution of volcanic catchments in Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Troch, P. A. A.

    2015-12-01

    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 co-evolution 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 0.22 to 82Ma) in Japan. We derived indices of landscape properties (drainage density) as well as hydrological response (annual water balance, baseow index, and flow duration curves) and examined their relation with catchment age and climate (through the aridity index). We found signicant correlation between drainage density and baseow index with age, but not with climate. The age of the catchments was also signicantly related to intra-annual flow variability. Younger catchments tend to have lower peak flows and higher low flows, while older catchments exhibit more flashy runoff. The decrease of baseflow with catchment age confirms previous studies that hypothesized that in volcanic landscapes the major flow pathways have changed over time, from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in similar volcanic catchments but of signicant younger age than the ones explored here. In these younger catchments, an increase in drainage density with age was observed, and it was hypothesized that this was because of more landscape incision due to increasing near-surface lateral flow paths in more mature catchments. Our results suggest that as catchments further evolve, hydrologically active channels retreat as less recharge leads to lower average aquifer levels

  3. 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. PMID:14653632

  4. 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.

  5. 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.

  6. Climate change influence on catchment sediment yield

    NASA Astrophysics Data System (ADS)

    Rulli, Maria Cristina; Grossi, Giovanna

    2010-05-01

    The effects of a change in climate are expected to be recognizable in many environmental aspects even at small spatial scales: atmospheric carbon dioxide concentration, air temperature, precipitation pattern (days of snowfall translate in days of rainfall), rainfall intensity and erosivity. As a consequence, strong modifications may affect the rate of evapo-transpiration, infiltration and plant biomass production, but also of the soil erosion. To which extent climate change may affect runoff production, soil erosion and sediment transport in upland catchments is investigated here by combining data of long term precipitation, sediment yield and future climate change provided by Global Circulation Models (GCMs) with a spatially distributed modeling approach to flow generation and surface erosion. The model accounts for changes in the structure and properties of soil and vegetation cover by combining the tube-flux approach to the topographic watershed partitioning through a parsimonious parametrization of the main hydrological processes. This model is used to predict hydrological and sediment fluxes for three small catchments in Saint Gabriel mountains of Southern California under control and climate change conditions. Simulation runs using a 45 years long record of hourly precipitation, both observed and referred to a future scenario, show that climate change may induce a significant modification in the catchment response to storms, with major effects on erosion and flood flows.

  7. Sensitivity maps for impacts of land management on an extreme flood in the Hodder catchment, UK

    NASA Astrophysics Data System (ADS)

    O'Donnell, G.; Ewen, J.; O'Connell, P. E.

    It is increasingly recognised that the management of land and the management of water are strongly interdependent, and that integrated management approaches are needed. There is evidence that modern land management practices have an effect on runoff generation in rural upland areas, so there is the potential to use land management control as a tool in flood risk mitigation programmes. Flooding from historical extreme rainfall events must be considered when designing mitigation programmes, especially if the designs have to take into account the possibility that such events will become more frequent in the future. The largest 90 min rainfall ever recorded in the UK was 117 mm, recorded in 1967 in the Dunsop tributary (25 km 2) of the Hodder catchment, northwest England. Extensive land management changes have recently been made in the catchment, including peat restoration, tree planting and reductions in sheep stocking density, and the analysis of the flooding in 1967 has been undertaken as part of a wider study on the potential impact of the recent changes. A method is demonstrated in which maps of sensitivity are plotted which show how peak flows for extreme events are affected by spatial patterns of changes in runoff generation. This method uses a gridded model for runoff generation containing an embedded hydraulic model of the river network which can calculate sensitivities efficiently and accurately using reverse algorithmic differentiation. The modelling examines the sensitivity of the hydrograph peak at the catchment outlet to changes in flashy runoff generation, which can be affected by land management practices including the blocking of open drainage channels in peat moorland. It is concluded that, as a result of hydraulic and geomorphologic dispersion in the network, changes in land management that affect the flashiness of runoff generation at small scales would probably have had only a relatively minor effect on the flow peaks at the outlet from the

  8. Assessment of contaminant fate in catchments using a novel integrated hydrobiogeochemical-multimedia fate model.

    PubMed

    Nizzetto, Luca; Butterfield, Dan; Futter, Martyn; Lin, Yan; Allan, Ian; Larssen, Thorjørn

    2016-02-15

    Models for pollution exposure assessment typically adopt an overly simplistic representation of geography, climate and biogeochemical processes. This strategy is unsatisfactory when high temporal resolution simulations for sub-regional spatial domains are performed, in which parameters defining scenarios can vary interdependently in space and time. This is, for example, the case when assessing the influence of biogeochemical processing on contaminant fate. Here we present INCA-Contaminants, the Integrated Catchments model for Contaminants; a new model that simultaneously and realistically solves mass balances of water, carbon, sediments and contaminants in the soil-stream-sediment system of catchments and their river networks as a function of climate, land use/management and contaminant properties. When forced with realistic climate and contaminant input data, the model was able to predict polychlorinated biphenyls (PCBs) concentrations in multiple segments of a river network in a complex landscape. We analyzed model output sensitivity to a number of hydro-biogeochemical parameters. The rate of soil organic matter mineralization was the most sensitive parameter controlling PCBs levels in river water, supporting the hypothesis that organic matter turnover rates will influence re-mobilization of previously deposited PCBs which had accumulated in soil organic matrix. The model was also used to project the long term fate of PCB 101 under two climate scenarios. Catchment diffuse run-off and riverine transport were the major pathways of contaminant re-mobilization. Simulations show that during the next decade the investigated boreal catchment will shift from being a net atmospheric PCB sink to a net source for air and water, with future climate perturbation having little influence on this trend. Our results highlight the importance of using credible hydro-biogeochemical simulations when modeling the fate of hydrophobic contaminants. PMID:26674684

  9. PAI-OFF: A new proposal for online flood forecasting in flash flood prone catchments

    NASA Astrophysics Data System (ADS)

    Schmitz, G. H.; Cullmann, J.

    2008-10-01

    SummaryThe Process Modelling and Artificial Intelligence for Online Flood Forecasting (PAI-OFF) methodology combines the reliability of physically based, hydrologic/hydraulic modelling with the operational advantages of artificial intelligence. These operational advantages are extremely low computation times and straightforward operation. The basic principle of the methodology is to portray process models by means of ANN. We propose to train ANN flood forecasting models with synthetic data that reflects the possible range of storm events. To this end, establishing PAI-OFF requires first setting up a physically based hydrologic model of the considered catchment and - optionally, if backwater effects have a significant impact on the flow regime - a hydrodynamic flood routing model of the river reach in question. Both models are subsequently used for simulating all meaningful and flood relevant storm scenarios which are obtained from a catchment specific meteorological data analysis. This provides a database of corresponding input/output vectors which is then completed by generally available hydrological and meteorological data for characterizing the catchment state prior to each storm event. This database subsequently serves for training both a polynomial neural network (PoNN) - portraying the rainfall-runoff process - and a multilayer neural network (MLFN), which mirrors the hydrodynamic flood wave propagation in the river. These two ANN models replace the hydrological and hydrodynamic model in the operational mode. After presenting the theory, we apply PAI-OFF - essentially consisting of the coupled "hydrologic" PoNN and "hydrodynamic" MLFN - to the Freiberger Mulde catchment in the Erzgebirge (Ore-mountains) in East Germany (3000 km 2). Both the demonstrated computational efficiency and the prediction reliability underline the potential of the new PAI-OFF methodology for online flood forecasting.

  10. Spatial interpolation of daily rainfall at catchment scale: a case study of the Ourthe and Ambleve catchments, Belgium

    NASA Astrophysics Data System (ADS)

    Ly, S.; Charles, C.; Degré, A.

    2010-09-01

    Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (krigings) are widely used in spatial interpolation from point measurement to continuous surfaces. However, the majority of existing geostatistical algorithms are available only for single-moment data. The first step in kriging computation is the semi-variogram modelling which usually uses only one variogram model for all-moment data. The objective of this paper was to develop different algorithms of spatial interpolation for daily rainfall on 1 km2 regular grids in the catchment area and to compare the results of geostatistical and deterministic approaches. In this study, we used daily rainfall data from 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km2). This area lies between 35 and 693 m in elevation and consists of river networks, which are tributaries of the Meuse River. For geostatistical algorithms, Cressie's Approximate Weighted Least Squares method was used to fit seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) to daily sample semi-variogram on a daily basis. Seven selected raingages were used to compare the interpolation performance of these algorithms applied to many degenerated-raingage cases. Spatial interpolation with the geostatistical and Inverse Distance Weighting (IDW) algorithms outperformed considerably interpolation with the Thiessen polygon that is commonly used in various hydrological models. Kriging with an External Drift (KED) and Ordinary Cokriging (OCK) presented the highest Root Mean Square Error (RMSE) between the geostatistical and IDW methods. Ordinary Kriging (ORK) and IDW were considered to be the best methods, as they provided smallest RMSE value for nearly all cases.

  11. The regime of sediment transport in the Soloneţ Catchment (Romania): quantification of the controlling factors

    NASA Astrophysics Data System (ADS)

    Niga, Bogdan; Obreja, Florin; Robu, Delia; Rǎdoane, Maria

    2016-04-01

    This paper focuses on the regime of sediment transportation to the river mouth of a catchment of 206 km2, located on the easternmost side of the Eastern Carpathians (NE Romania). The primary aim of the paper is to attempt a quantification of the catchment controlling factors of the sediment volume transited through the drainage network and their annual and multi-annual distribution. Among these factors we will focus on the role of sediment sources and human interventions in the mobilization of sediments towards rivers. The data employed in this study were obtained from the Parhauti gauging station (1973 to 2014), located at a distance of about 1.7 km from the confluence of the Solonet River with the Suceava River. These are represented of measurements of water discharge, suspended sediment discharge (hourly or daily measurements during flash flood intervals) and monthly values. The data were correlated with records on rainfall, local slope and morphological characteristics of the river crosssection. For a more detailed analysis we introduced a further comparison with records obtained at other gauging stations, located within the same physical-geographical settings, in neighboring catchments. Regarding our study catchment, investigations were performed on all variables that control flow formation and sediment load of water flows, i.e. geologic substrate, landforms, catchment morphometry, characteristics of the drainage network, land use, types of human interventions in the catchment area and on the river network. The average drainage network density equals ca. 2.5 km / km2, ranging from less than 1 km / km2 at the watershed, to the maximum of over 4 km / km2 recorded at the cuesta frontslopes. The multi-annual average amount of suspended sediment transport is 3.06 kg / s. Suspended sediment transport occurs most intensely during summer (months VI-VIII), (59.8%) as a result of floods which enhance the power of the river. During winter months (XII-II), sediment

  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. Leaching of nitrogen from forested catchments in Finland

    NASA Astrophysics Data System (ADS)

    Kortelainen, Pirkko; Saukkonen, Sari; Mattsson, Tuija

    1997-12-01

    This study provides an assessment on the spatial variability of the long-term leaching (8-23 years) of nitrogen and organic carbon from 22 forested catchments (0.69-56 km2). The catchments are located throughout Finland excluding the northernmost regions. The Kruunuoja catchment is located in a national park; the other catchments represent typical Finnish forestry land. The leaching from the 21 forestry land catchments can be considered to represent average leaching from Finnish forestry land since the most important forestry practices (ditching, clear-cutting, scarification, and fertilization) since the 1960s have affected about 2.4% of the catchment area per year (compare 2.5% in the entire country in 1980 and 2% in 1991). Moreover, the mean annual runoff from the catchments, 230-420 mm yr-1, agree with the mean annual runoff from Finland (301 mm yr-1 from 1931 to 1990). The major part of the nitrogen transported from the catchments consisted of organic nitrogen (on average 79%). The average inorganic nitrogen proportion ((NO3-N + NH4-N)/Ntot) was lowest (7.3%) in the Kruunuoja catchment and was highest (54%) in the southernmost Teeressuonoja catchment located in the highest anthropogenic nitrogen deposition area. The median C/N ratio in the study streams was high, ranging from 34 to 66. Nitrate leaching from the catchments varied between 2.8 (Kruunuoja) and 100 kg km-2 yr-1 (Teeressuonoja) and was negatively related to C/N ratio in stream water and latitude. The stepwise multiple regression model selected C/N ratio and nitrogen deposition which together explained 72% of the variation in NO3-N leaching. Retention of NO3-N deposition (calculated as ((input-output)/input) was high in all catchments, ranging from 0.99 in Kruunuoja to 0.67 in Teeressuonoja.

  14. 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

  15. The hydrological response of a small catchment after the abandonment of terrace cultivation. A study case in northwestern Spain

    NASA Astrophysics Data System (ADS)

    Llorente-Adán, Jose A.; Lana-Renault, Noemí; Galilea, Ianire; Ruiz-Flaño, Purificacion

    2015-04-01

    Terrace construction for cultivation results in a complete transformation of the hillslopes to a series of flat sectors and almost vertical steps. This strategy, which involves a redistribution of soils and a re-organization of the drainage network, provides fertile soil over steep slopes, improves infiltration and controls overland flow under conditions of intense rainstorms. In Camero Viejo (north-western Iberian ranges) most of the hillslopes are occupied by terraced fields. During the XXth century, rural population declined and agricultural practices were abandoned. In this area, a small catchment (1.9 km2) was monitored in 2012 for studying how the abandonment of agricultural terraces affect water and sediment transfer from the hillslopes to the channels. Terraces occupy 40% of the catchment and are covered by sparse grass and shrubs. The equipment installed in the catchment registers continuously meteorological data, discharge and water table fluctuations. Data on suspended sediment transport is obtained by means of a rising-stage sampler. Here we present the hydrological results corresponding to the years 2012-13 and 2013-14. The hydrological response of the catchment was moderate (annual runoff coefficient < 0.20), which could be in part explained by the high evapotranspiration rates reported in the area. Lows flows were recorded in summer and autumn, when the water reserves of the catchment were dry, and high flows occurred from January, when the catchment became wetter. The shape of the hydrographs, with slow response times, moderate peakflows and long recession limbs suggested a large contribution of subsurface flow, probably favored by deep and well structured soils in the bench terraces. Soil saturation areas were not observed during the study period, suggesting that soil infiltration processes and subsurface flow are important, and that the drainage system of the terraces is probably well maintained. No suspended sediment has been collected so far

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

    NASA Astrophysics Data System (ADS)

    Archfield, S. A.; Pugliese, A.; Castellarin, A.; Skøien, J. O.; Kiang, J. E.

    2013-04-01

    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.

  17. 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.

  18. Snowcover interaction with climate, topography & vegetation in mountain catchments in catchments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mountainous regions in the semi-arid Western US are snow-dominated with little or no summer precipitation. Wind and topographic structure control snow deposition, causing tremendous spatial heterogeneity in the distribution of the snowcover and the delivery of melt water across mountain catchments....

  19. 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. PMID:25395322

  20. 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.

  1. 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.

  2. Describing Ecosystem Complexity through Integrated Catchment Modeling

    NASA Astrophysics Data System (ADS)

    Shope, C. L.; Tenhunen, J. D.; Peiffer, S.

    2011-12-01

    Land use and climate change have been implicated in reduced ecosystem services (ie: high quality water yield, biodiversity, and agricultural yield. The prediction of ecosystem services expected under future land use decisions and changing climate conditions has become increasingly important. Complex policy and management decisions require the integration of physical, economic, and social data over several scales to assess effects on water resources and ecology. Field-based meteorology, hydrology, soil physics, plant production, solute and sediment transport, economic, and social behavior data were measured in a South Korean catchment. A variety of models are being used to simulate plot and field scale experiments within the catchment. Results from each of the local-scale models provide identification of sensitive, local-scale parameters which are then used as inputs into a large-scale watershed model. We used the spatially distributed SWAT model to synthesize the experimental field data throughout the catchment. The approach of our study was that the range in local-scale model parameter results can be used to define the sensitivity and uncertainty in the large-scale watershed model. Further, this example shows how research can be structured for scientific results describing complex ecosystems and landscapes where cross-disciplinary linkages benefit the end result. The field-based and modeling framework described is being used to develop scenarios to examine spatial and temporal changes in land use practices and climatic effects on water quantity, water quality, and sediment transport. Development of accurate modeling scenarios requires understanding the social relationship between individual and policy driven land management practices and the value of sustainable resources to all shareholders.

  3. 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.

  4. Equitable water allocation in a heavily committed international catchment area: the case of the Komati Catchment

    NASA Astrophysics Data System (ADS)

    Nkomo, Sakhiwe; van der Zaag, Pieter

    This paper investigates water availability and use in the Komati catchment. The Komati catchment is shared by Swaziland and South Africa and forms part of the Incomati basin, with Mozambique as the third riparian country. In 2002 the three countries reached agreement about how the scarce water should be allocated, based on the principle of equitable and sustainable utilization, as stipulated by the SADC Protocol. The Komati catchment has five main water uses: afforestation, irrigation, the environment, urban/industrial/mining (UIM), and interbasin water transfers (for industrial use). In addition, South Africa and Swaziland have committed themselves to satisfy a certain cross border flow to downstream Mozambique. Frequently, debate has arisen between users and riparian countries on the direction that water resources development has taken in the catchment. Downstream farmers have often complained about interbasin transfers taking place in the upstream portions of the catchment. There has also been animosity about effecting environmental flow releases. A relatively simple, spreadsheet-based water resources model (Waflex) was developed to analyse water availability and use under current and future scenarios. The results were then compared to results obtained from another model that was used in a joint study by Mozambique, South Africa and Swaziland. The Waflex model showed a high degree of consistency with the one used for comparison, especially in terms of trends. It was found that the recent completion of two new dams has improved water supply to irrigation in the two countries. Future water demands will result in appreciable shortages for irrigation and domestic use. The agreed maximum development levels will soon outstrip the ability of the catchment’s supply. The paper shows that a combination of measures will be required to ensure equitable and sustainable water utilisation in the Komati catchment. These will have to be agreed by the riparian countries

  5. 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.

  6. 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

  7. Catchment controls and human disturbances on the geomorphology of small Mediterranean estuarine systems

    NASA Astrophysics Data System (ADS)

    Estrany, Joan; Grimalt, Miquel

    2014-10-01

    Geographic signatures are physical and human-induced characteristics or processes that identify comparable or unique features of estuaries along latitudinal gradients. In Mediterranean areas, the microtidal regime and the strong seasonal and inter-annual contrasts cause an alternation between relatively high runoff and arid conditions. Furthermore, the long history of human settlement also increases the complexity in the study of these estuarine systems. This study investigates these signatures of the estuaries located within the Mallorcan eastern coast, which are geomorphologically homogeneous because of a similar bedrock geology and Holocene history. A multi-method approach focused on the integration of geomorphometry, hydraulics, historical sources and statistics was used. We explore the role played by catchment morphometric parameters, severe flash flood events and human disturbances in controlling the geomorphology of 10 beach-barrier enclosed, fluvial incised lagoons. Most of the lagoons discharge into 'calas', ranging in size from 1345 to 17,537 m2 and their related catchments are representative of the Mediterranean hydrological systems. Multiple regression models illustrate that the size, slope and drainage network development of the catchments explain the variance in length (r2 = 0.67), volume (r2 = 0.49), area (r2 = 0.64), circularity (r2 = 0.72) and average width (r2 = 0.81) of the lagoons. Depending on these catchment morphometric variables, the shape of the lagoons is also determined by the occurrence of catastrophic flash floods, which cause scouring and dredging, whereas the ordinary flood events and sea storms promote refilling and sedimentation. A historical analysis since 1850 documented 18 flood events, 5 of which were catastrophic with destructive effects along the catchments and large morphological changes in coastal lagoons. High intensity rainfall (up to 200 mm in 2 h), the geomorphometry of the catchments and the massive construction of

  8. 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.

  9. 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

  10. Assessing catchment connectivity using hysteretic loops

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia; Masselink, Rens; Goni, Mikel; Campo, Miguel Angel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel

    2015-04-01

    Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within landscapes. This information is valuable for land managers to be able to take appropriate action at the correct place. Hysteresis between sediment and water discharge can give important information about the sources , pathways and conditions of sediment that arrives at the outlet of a catchment. "Hysteresis" happens when the sediment concentration associated with a certain flow rate is different depending on the direction in which the analysis is performed -towards the increase or towards the diminution of the flow. This phenomenon to some extent reflects the way in which the runoff generation processes are conjugated with those of the production and transport of sediments, hence the usefulness of hysteresis as a diagnostic hydrological parameter. However, the complexity of the phenomena and factors which determine hysteresis make its interpretation uncertain or, at the very least, problematic. Many types of hysteretic loops have been described as well as the cause for the shape of the loop, mainly describing the origin of the sediments. In this study, several measures to objectively classify hysteretic loops in an automated way were developed. These were consecutively used to classify several hundreds of loops from several agricultural catchments in Northern Spain. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz "principal", Op, and Oskotz "woodland", Ow). La Tejería and Latxaga watersheds, located in the Central Western part of Navarre, are roughly similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (fine texture topsoil), climate (humid sub Mediterranean) and land use (80-90% cultivated with winter grain crops

  11. Identification of catchment functional units by time series of thermal remote sensing images

    NASA Astrophysics Data System (ADS)

    Müller, B.; Bernhardt, M.; Schulz, K.

    2014-12-01

    The identification of catchment functional behavior with regards to water and energy balance is an important step during the parameterization of land surface models. An approach based on time series of thermal infrared (TIR) data from remote sensing is developed and investigated to identify land surface functioning as is represented in the temporal dynamics of land surface temperature (LST). For the mesoscale Attert catchment in midwestern Luxembourg, a time series of 28 TIR images from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) was extracted and analyzed, applying a novel process chain. First, the application of mathematical-statistical pattern analysis techniques demonstrated a strong degree of pattern persistency in the data. Dominant LST patterns over a period of 12 years were then extracted by a principal component analysis. Component values of the two most dominant components could be related for each land surface pixel to land use data and geology, respectively. The application of a data condensation technique ("binary words") extracting distinct differences in the LST dynamics allowed the separation into landscape units that show similar behavior under radiation-driven conditions. It is further outlined that both information component values from principal component analysis (PCA), as well as the functional units from the binary words classification, will highly improve the conceptualization and parameterization of land surface models and the planning of observational networks within a catchment.

  12. Hydrological ensemble forecasting in mesoscale catchments: Sensitivity to initial conditions and value of reforecasts

    NASA Astrophysics Data System (ADS)

    Fundel, Felix; Zappa, Massimiliano

    2011-09-01

    Hydrological forecasts can benefit from model climatologies compiled from long, consistent, retrospective forecasts (reforecasts). Typical areas of application include the estimation of return periods for extreme events, the detection of model deficiencies, such as systematic errors or the calibration of current forecasts using the reforecasts, and suitable observations. One difficulty when creating long reforecasts is the availability of good states for the model initialization, as a sufficiently dense network of meteorological observations is rarely available in most catchments for a long period. With this study, the creation of forecast and reforecasts in such catchments is motivated by considering two aspects: first, a comparison where it is shown that hydrological forecasts benefit most from high-quality initial conditions on the basis of local observations, however, less accurate initial conditions using ERA-interim reanalysis are also sufficient to provide skillful hydrological forecasts useful for many users. Second, we demonstrate that hydrological reforecasts compiled without long-term meteorological observations have an additional value, e.g., they allow for more skillful runoff forecasts. Utilizing those reforecasts can compensate for forecast errors induced by less accurate initializations. For this study, hourly hydrological reforecasts, based on the PREcipitation-Runoff-EVApotranspiration HRU Model (PREVAH) were used, with an 18 year long, five-member global ensemble reforecast data set from the European Centre for Medium Range Weather Forecasts (ECMWF) Variable Resolution Ensemble Prediction System (VarEPS) as forcing for lead times up to 10 days. Three mesoscale catchments of different characteristics in the Swiss Alps were analyzed.

  13. 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

  14. 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. PMID:27280603

  15. Range-wide selection of catchments for Pacific salmon conservation.

    PubMed

    Pinsky, Malin L; Springmeyer, Dane B; Goslin, Matthew N; Augerot, Xanthippe

    2009-06-01

    Freshwater ecosystems are declining in quality globally, but a lack of data inhibits identification of areas valuable for conservation across national borders. We developed a biological measure of conservation value for six species of Pacific salmon (Oncorhynchus spp.) in catchments of the northern Pacific across Canada, China, Japan, Russia, and the United States. We based the measure on abundance and life-history richness and a model-based method that filled data gaps. Catchments with high conservation value ranged from California to northern Russia and included catchments in regions that are strongly affected by human development (e.g., Puget Sound). Catchments with high conservation value were less affected by agriculture and dams than other catchments, although only 1% were within biodiversity reserves. Our set of high-value areas was largely insensitive to simulated error, although classification remained uncertain for 3% of catchments. Although salmon face many threats, we propose they will be most likely to exhibit resilience into the future if a complementary mosaic of conservation strategies can be proactively adopted in catchments with healthy salmon populations. Our analysis provides an initial map of where these catchments are likely to be located. PMID:19220368

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

    NASA Astrophysics Data System (ADS)

    Patil, Sopan D.; Wigington, Parker J.; Leibowitz, Scott G.; Sproles, Eric A.; Comeleo, Randy L.

    2014-09-01

    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 (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model are implemented at 41 meso-scale (500-5000 km2) catchments in the Pacific Northwest region of USA. We use two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyze the performance improvement with distributed model. Results show that the distributed model performs better than the lumped model in 38 out of 41 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone is insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM is a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV is 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 a homogeneous moisture distribution benefit from spatially distributed meteorological inputs if they also have high spatial variability of precipitation phase (rain vs. snow).

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  18. A detailed study on Catchment delineation for Urban areas

    NASA Astrophysics Data System (ADS)

    Sharma, B.; B M, A.; Lohani, B.; Jain, A.

    2015-12-01

    Urban flood modelling is carried out for predicting, analysing and planning of floods in urban areas. Catchment information is an important input for urban flood modelling. Automatic catchment delineation at gully gratings for urban areas using appropriate software packages/methods along with an appropriate set of input data and parameters is still a research challenge. Considering the above, the aim of this study is to (i) identify the best suitable software for automatic catchment delineation by considering gully grating as outlet (ii) understand the effect of resolution of DEM on catchments delineated (iii) understand whether to consider DEM or DSM for catchment delineation (iv) study the effect of grid based and TIN based DEM. In this study catchment delineation has been investigated considering IIT Kanpur as a study site. LiDAR data are used to generate DEM/DSM of the study area. A comparative study of catchment delineation has been carried out between ArcHydro 10.1, BASINS 4.1, ArcSWAT, WMS 7.1, and HEC-GeoHMS approaches. Catchments have been delineated for different drainage threshold areas using gully grating points as outlets and their effects have been compared for the aforementioned software. In order to understand the effect of resolution of data, DEMs of 1m and 5m resolution have been generated and compared against each other. Effects of building ridge lines and their contribution to catchment delineation has been studied by generating a DSM of 1m resolution, and comparing the results with catchments delineated using 1m DEM. In order to assess the effects of the types of DEM over catchment delineation, a grid based DEM and TIN based DEM are compared against each other using WMS 7.1 software. The results for the catchment delineation using various software illustrate that ArcHydro 10.1 performs better than any other aforementioned software. Also, it is noted that varied drainage threshold area parameters, resolutions of DEM, selection of DEM

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  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. Fluvial sediment inputs to upland gravel bed rivers draining forested catchments: potential ecological impacts

    NASA Astrophysics Data System (ADS)

    Marks, S. D.; Rutt, G. P.

    As identified by the detailed long-term monitoring networks at Plynlimon, increased sediment supply to upland fluvial systems is often associated with forestry land-use and practice. Literature is reviewed, in the light of recent results from Plynlimon sediment studies, to enable identification of the potential ecological impacts of fluvial particulate inputs to upland gravel bed rivers draining forested catchments similar to the headwaters of the River Severn. Both sediment transport and deposition can have significant impacts upon aquatic vertebrates, invertebrates and plants.

  7. Catchment mixing processes and travel time distributions

    NASA Astrophysics Data System (ADS)

    Botter, Gianluca

    2012-05-01

    This work focuses on the description and the use of the probability density functions (pdfs) of travel, residence and evapotranspiration times, which are comprehensive descriptors of the fate of rainfall water particles traveling through catchments, and provide key information on hydrologic flowpaths, partitioning of precipitation, circulation and turnover of pollutants. Exploiting some analytical solutions to the transport problem derived by Botter et al. (2011), this paper analyzes the features of travel, residence and evapotranspiration time pdfs resulting from different assumptions on the mixing processes occurring during streamflow formation and plant uptake (namely, complete mixing and translatory flow). The ensuing analytical solutions are analyzed through numerical Monte Carlo simulations of a stochastic model of soil moisture and streamflow dynamics. Travel and residence time pdfs are shown to be time-variant as they mirror the variability of the relevant hydrological fluxes. In particular, the temporal fluctuations of the mean residence time are shown to reflect rainfall dynamics, whereas the variability of the mean travel time is chiefly driven by streamflow dynamics, with lower frequency and higher amplitude fluctuations. Dry climates enhance the effect of the type of mixing on catchment transport features (e.g., mean travel times and seasonal dynamics of stream concentrations). The implications for the interpretation of tracer experiments are also discussed, showing through specific examples that models disregarding nonstationarity may significantly misestimate travel time pdfs.

  8. Towards catchment classification in data-scarce regions

    DOE PAGESBeta

    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,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

  9. 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.

    2015-12-01

    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.

  10. Transport of a nematicide in surface and ground waters in a farmed tropical catchment with volcanic substratum

    NASA Astrophysics Data System (ADS)

    Charlier, J.-B.; Cattan, P.; Voltz, M.; Moussa, R.

    2009-04-01

    Assessment of water-pollution risks in agricultural regions requires studying pesticide transport processes in soil and water compartments at the catchment scale. In tropical regions, banana (Musa spp.) plantations are located in zones with abundant rainfalls and soils with high infiltration rates, which lead to washout and leaching of soil-applied pesticides, causing severe diffuse pollution of water resources. The aim of this paper is to determine how the nematicide cadusafos [S,S-di-sec-butyl O-ethyl phosphorodithioate], used in banana plantations, contaminates water and soils at the two scales of subcatchment and catchment. The study site was a small banana-growing catchment on the tropical volcanic island of Guadeloupe in the Caribbean (FWI). The catchment is located in pedoclimatic conditions where rainfall is abundant (> 4000 mm/year), and soil permeable (saturated hydraulic conductivity of Andosol Ks > 30 mm/h). Two campaigns of nematicide application were conducted, one in 2003 over 40% of the catchment and one in 2006 over 12%. For 100 days after application, we monitored the surface water and groundwater flows and the cadusafos concentrations in the soil and in surface and ground waters in a 2400 m² subcatchment and a 17.8 ha catchment. The results show that at the subcatchment scale the high retention in the A horizon of the soil limited the transport of cadusafos by runoff, whereas the lower retention of the molecule in the B horizon favoured percolation towards the shallow groundwater. The contamination levels of surface water, as well as shallow and deep groundwaters, reflected the geological structure of the Féfé catchment: i.e. a shallow aquifer in the most recent volcanic deposits that is rapidly exposed to pollution and a deeper aquifer that is relatively protected from the pollution coming from the treated fields. Comparing the losses of cadusafos at the subcatchment and at the catchment scales revealed that the nematicide re-infiltrated in

  11. 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

  12. 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

  13. 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

  14. 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

  15. Estimation of Catchment Transit Time in Fuji River Basin by using an improved Tank model

    NASA Astrophysics Data System (ADS)

    Wenchao, M.; Yamanaka, T.; Wakiyama, Y.; Wang, P.

    2013-12-01

    As an important parameter that reflects the characteristics of catchments, the catchment transit time (CTT) has been given much more widely attentions especially in recent years. The CTT is defined as the time water spends travelling through a catchment to the stream network [1], and it describes how catchments retain and release water and solutes and thus control geochemical and biogeochemical cycling and contamination persistence [2]. The objectives of the present study are to develop a new approach for estimating CTT without prior information on such TTD functions and to apply it to the Fuji River basin in the Central Japan Alps Region. In this study, an improved Tank model was used to compute mean CTT and TTD functions simultaneously. It involved water fluxes and isotope mass balance. Water storage capacity in the catchment, which strongly affects CTT, is reflected in isotope mass balance more sensitively than in water fluxes. A model calibrated with observed discharge and isotope data is used for virtual age tracer computation to estimate CTT. This model does not only consider the hydrological data and physical process of the research area but also reflects the actual TTD with considering the geological condition, land use and the other catchment-hydrological conditions. For the calibration of the model, we used river discharge record obtained by the Ministry of Land, Infrastructure and Transportation, and are collecting isotope data of precipitation and river waters monthly or semi-weekly. Three sub-catchments (SC1~SC3) in the Fuji River basin was selected to test the model with five layers: the surface layer, upper-soil layer, lower-soil layer, groundwater aquifer layer and bedrock layer (Layer 1- Layer 5). The evaluation of the model output was assessed using Nash-Sutcliffe efficiency (NSE), root mean square error-observations standard deviation ratio (RSR), and percent bias (PBIAS). Using long time-series of discharge records for calibration, the simulated

  16. 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.

  17. The Hydrologic Response of a Small Catchment to Clear Cutting

    NASA Astrophysics Data System (ADS)

    Abdelnour, A.; Stieglitz, M.; Pan, F.; McKane, R. B.

    2006-12-01

    We simulated how a landscape disturbance (i.e., 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 moisture and discharge. The study site is the WS10 catchment of the HJ Andrews LTER, located in the Pacific NorthWest, USA. We used a spatially- explicit hydrologic model comprised of connected landscape units. We implicitly model biomass removal and the subsequent forest re-growth by manipulating evapotranspiration. We allow potential evapotranspiration to increase exponentially from zero at the onset of the disturbance to pre-disturbance values within a 40 years period. Simulations show that while soil moisture in the uplands increased in post-disturbance period, downslope flow increased only minimally. In this catchment, upland soil moisture stayed well below field capacity, and therefore, downslope lateral flow was not initiated. As such, midland and lowland soil moisture, as well as catchment discharge, remained near pre-disturbance values throughout the re-growth period. This behavior in catchment dynamics resulted primarily from the fact that seasonal temperatures and precipitations are out of phase in this region of the US.

  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. Chemical weathering and runoff chemistry in a steep headwater catchment

    NASA Astrophysics Data System (ADS)

    Anderson, Suzanne Prestrud; Dietrich, William E.

    2001-07-01

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

  20. Uncertainty in hydrological signatures for gauged and ungauged catchments

    NASA Astrophysics Data System (ADS)

    Westerberg, Ida K.; Wagener, Thorsten; Coxon, Gemma; McMillan, Hilary K.; Castellarin, Attilio; Montanari, Alberto; Freer, Jim

    2016-03-01

    Reliable information about hydrological behavior is needed for water-resource management and scientific investigations. Hydrological signatures quantify catchment behavior as index values, and can be predicted for ungauged catchments using a regionalization procedure. The prediction reliability is affected by data uncertainties for the gauged catchments used in prediction and by uncertainties in the regionalization procedure. We quantified signature uncertainty stemming from discharge data uncertainty for 43 UK catchments and propagated these uncertainties in signature regionalization, while accounting for regionalization uncertainty with a weighted-pooling-group approach. Discharge uncertainty was estimated using Monte Carlo sampling of multiple feasible rating curves. For each sampled rating curve, a discharge time series was calculated and used in deriving the gauged signature uncertainty distribution. We found that the gauged uncertainty varied with signature type, local measurement conditions and catchment behavior, with the highest uncertainties (median relative uncertainty ±30-40% across all catchments) for signatures measuring high- and low-flow magnitude and dynamics. Our regionalization method allowed assessing the role and relative magnitudes of the gauged and regionalized uncertainty sources in shaping the signature uncertainty distributions predicted for catchments treated as ungauged. We found that (1) if the gauged uncertainties were neglected there was a clear risk of overconditioning the regionalization inference, e.g., by attributing catchment differences resulting from gauged uncertainty to differences in catchment behavior, and (2) uncertainty in the regionalization results was lower for signatures measuring flow distribution (e.g., mean flow) than flow dynamics (e.g., autocorrelation), and for average flows (and then high flows) compared to low flows.

  1. Catchment Classification via Hydrologic Modeling: Evaluating the Relative Importance of Model Selection, Parameterization and Classification Techniques

    NASA Astrophysics Data System (ADS)

    Marshall, L. A.; Smith, T. J.; To, L.

    2015-12-01

    Classification has emerged as an important tool for evaluating the runoff generating mechanisms in catchments and for providing a basis on which to group catchments having similar characteristics. These methods are particularly important for transferring models from one catchment to another in the case of data scarce regions or paired catchment studies .In many cases, the goal of catchment classification is to be able to identify models or parameter sets that could be applied to similar catchments for predictive purposes. A potential impediment to this goal is the impact of error in both the classification technique and the hydrologic model. In this study, we examine the relationship between catchment classification, hydrologic models, and model parameterizations for the purpose of transferring models between similar catchments. Building on previous work using a data set of over 100 catchments from south-east Australia, we identify several hydrologic model structures and calibrate each model for each catchment. We use clustering to identify groups of catchments with similar hydrologic response (as characterized through the calibrated model parameters). We examine the dependency of the clustered catchment groups on the pre-selected model, the uncertainty in the calibrated model parameters, and the clustering or classification algorithm. Further, we investigate the relationship between the catchment clusters and certain catchment physical characteristics or signatures, which are more typically used for catchment classification. Overall, our work is aimed at elucidating the potential sources of uncertainty in catchment classification, and the utility of classification for improving hydrologic predictions.

  2. 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.

  3. Characterisation of dispersion mechanisms in an urban catchment using a deterministic spatially distributed direct hydrograph travel time model

    NASA Astrophysics Data System (ADS)

    Rossel, F.; Gironas, J. A.

    2012-12-01

    The link between stream network structure and hydrologic response for natural basins has been extensively studied. It is well known that stream network organization and flow dynamics in the reaches combine to shape the hydrologic response of natural basins. Geomorphologic dispersion and hydrodynamic dispersion along with hillslope processes control to a large extent the overall variance of the hydrograph, particularly under the assumption of constant celerity throughout the basin. In addition, a third mechanism referred as to kinematic dispersion becomes relevant when considering spatial variations of celerity. On contrary, the link between the drainage network structure and overall urban terrain, and the hydrologic response in urban catchments has been much less studied. In particular, the characterization of the different dispersion mechanisms within urban areas remains to be better understood. In such areas artificial elements are expected to contribute to the total dispersion due to the variety of geometries and the spatial distribution of imperviousness. This work quantifies the different dispersion mechanisms in an urban catchment, focusing on their relevance and the spatial scales involved. For this purpose we use the Urban Morpho-climatic Instantaneous Unit Hydrograph model, a deterministic spatially distributed direct hydrograph travel time model, which computes travel times in hillslope, pipe, street and channel cells using formulations derived from kinematic wave theory. The model was applied to the Aubeniere catchment, located in Nantes, France. Unlike stochastic models, this deterministic model allows the quantification of dispersion mechanism at the local scale (i.e. the grid-cell). We found that kinematic dispersion is more relevant for small storm events, whereas geomorphologic dispersion becomes more significant for larger storms, as the mean celerity within the catchment increases. In addition, the total dispersion relates to the drainage area in

  4. 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

  5. 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.

  6. 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. PMID:19704140

  7. A learning framework for catchment erosion modelling

    NASA Astrophysics Data System (ADS)

    Freer, J. E.; Quinton, J.

    2006-12-01

    Erosion modelling at the catchment scale, like many other disciplines that model environmental signals, is not an exact science. We are limited by our incomplete perceptual understanding of relevant processes; in formulating and simplifying these perceptions into conceptual models; and by our ability to collect data at the right resolution and spatial scale to drive and evaluate our models effectively. The challenge is how to develop models which take into account our difficulties in describing processes, parameterising equations and demonstrating that they perform within acceptable limits. In this talk we will: examine how limited data has been used to develop algorithms applied across the world and how this may lead to one source of prediction error discuss the use of uncertainty analysis techniques for describing the possible suite of model predictions that give acceptable responses explore what field observations can tell us about model performance and how these might be used to constrain uncertainties in model predictions or in some cases contribute towards these uncertainties; consider how we might learn from our data to produce models with an appropriate degree of complexity We hope that the talk will begin a debate about our ability to capture the essence of erosional processes and quantities for storm responses through data and modelling that includes characterising the appropriate level of uncertainties. We will use examples from the literature as well as from our own observations and modelling initiatives. We hope to generate some lively discussion about the limits of our observations to both inform and to evaluate, to consider what the appropriate level of complexity should be for catchment scale erosion modelling and to consider ways to develop a learning framework for all erosion scientists to engage in.

  8. Modelling catchment areas for secondary care providers: a case study.

    PubMed

    Jones, Simon; Wardlaw, Jessica; Crouch, Susan; Carolan, Michelle

    2011-09-01

    Hospitals need to understand patient flows in an increasingly competitive health economy. New initiatives like Patient Choice and the Darzi Review further increase this demand. Essential to understanding patient flows are demographic and geographic profiles of health care service providers, known as 'catchment areas' and 'catchment populations'. This information helps Primary Care Trusts (PCTs) to review how their populations are accessing services, measure inequalities and commission services; likewise it assists Secondary Care Providers (SCPs) to measure and assess potential gains in market share, redesign services, evaluate admission thresholds and plan financial budgets. Unlike PCTs, SCPs do not operate within fixed geographic boundaries. Traditionally, SCPs have used administrative boundaries or arbitrary drive times to model catchment areas. Neither approach satisfactorily represents current patient flows. Furthermore, these techniques are time-consuming and can be challenging for healthcare managers to exploit. This paper presents three different approaches to define catchment areas, each more detailed than the previous method. The first approach 'First Past the Post' defines catchment areas by allocating a dominant SCP to each Census Output Area (OA). The SCP with the highest proportion of activity within each OA is considered the dominant SCP. The second approach 'Proportional Flow' allocates activity proportionally to each OA. This approach allows for cross-boundary flows to be captured in a catchment area. The third and final approach uses a gravity model to define a catchment area, which incorporates drive or travel time into the analysis. Comparing approaches helps healthcare providers to understand whether using more traditional and simplistic approaches to define catchment areas and populations achieves the same or similar results as complex mathematical modelling. This paper has demonstrated, using a case study of Manchester, that when estimating

  9. Soilwater dynamics related to waterlogging in a sloping catchment

    NASA Astrophysics Data System (ADS)

    Atputhanathan, C. S.; Gunawardena, E. R. N.; Rushton, K. R.

    1991-03-01

    A study to understand the factors contributing to waterlogging was conducted in a small catchment of 5.4 ha in an irrigation scheme in the Eastern Dry Zone of Sri Lanka. An analysis, based on climatological data, extensive measurements of inflows and outflows, groundwater head fluctuations, soil moisture content variations and soil properties, indicated that a single catchment water balance and the SEW index are of limited value due to the spatial nature of the waterlogging problem in this sloping catchment with surface irregularities. A distributed mathematical model was developed to represent the lateral and vertical components of flow; the agreement between the simulated and field results is satisfactory.

  10. Holocene sediments within lake catchments - testing sediment delivery

    NASA Astrophysics Data System (ADS)

    Dreibrodt, S.; Bork, H.-R.

    2009-04-01

    Results of detailed investigation of soils, colluvia and lake sediments in a lake catchment in northern Germany proves that the input of eroded soil (enabled by agricultural land use) is of a minor amount compared with the storage within colluvial layers. Pre-existing micro- and meso-topography and prehistorical land use patterns as well as precipitation intensity are probable to control the Holocene flux of sediments within the lake catchment area. Therefore we entertain some doubt if sediment delivery ratios- usually applied on larger spatial scales (e. g. river catchment areas)- are useful to produce reliable quantitative data of Holocene soil erosion in central Europe.