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Gilles Billen - One of the best experts on this subject based on the ideXlab platform.
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modelling faecal contamination in the scheldt Drainage Network
Journal of Marine Systems, 2013Co-Authors: Nouho Koffi Ouattara, Anouk De Brauwere, Gilles Billen, Pierre ServaisAbstract:This study developed a model simulating the seasonal and spatial variations of microbiological water quality (expressed in terms of Escherichia coli concentrations) in rivers. The model (SENEQUE-EC) consists of a microbiological module appended to a hydro-ecological model describing the functioning of the entire Scheldt Drainage Network. The microbiological module describes the sources of E. coli, their transport and the processes responsible for the fate of E. coli once released into the natural environment (mortality, settling and resuspension). This model differentiates the dynamics of three types of E. coli: free-floating E. coli, E. coli attached to suspended solids in the water column and E. coli present in sediments. The model was verified by comparison of its results with temporal and spatial distributions of field data in different stretches of rivers of the Scheldt Drainage Network. It was then used to test various scenarios involving diverse modifications in wastewater management, which was shown to be the most determining factor of microbiological water quality. Due to its low temporal resolution, the SENEQUE-EC is poorly adapted to describing the microbiological quality in areas under tidal influence. Therefore, the data of the SENEQUE-EC model were used as upstream boundary conditions to run a microbiological model with a high temporal resolution devoted to the tidal Scheldt River and Estuary (the SLIM-EC2 model).
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Modelling microbiological water quality in the Seine river Drainage Network: past, present and future situations
Hydrology and Earth System Sciences Discussions, 2007Co-Authors: P. Servais, Gilles Billen, A. Goncalves, T. Garcia-armisenAbstract:The Seine river watershed is characterized by a high population density and intense agricultural activities. Data show low microbiological water quality in the main rivers (Seine, Marne, Oise) of the watershed. Today, there is an increasing pressure from different social groups to restore microbiological water quality in order to both increase the safety of drinking water production and to restore the possible use of these rivers for bathing and rowing activities, as they were in the past. A model, appended to the hydro-ecological SENEQUE/Riverstrahler model describing the functioning of large river systems, was developed to describe the dynamics of faecal coliforms (FC), the most usual faecal contamination indicator. The model is able to calculate the distribution of FC concentrations in the whole Drainage Network resulting from land use and wastewater management in the watershed. The model was validated by comparing calculated FC concentrations with available field data for some well-documented situations in different river stretches of the Seine Drainage Network. Once validated, the model was used to test various predictive scenarios, as, for example, the impact of the modifications in wastewater treatment planned at the 2012 horizon in the Seine watershed in the scope of the implementation of the european water framework directive. The model was also used to investigate past situations. In particular, the variations of the microbiological water quality in the Parisian area due to population increase and modifications in wastewater management were estimated over the last century. It was shown that the present standards for bathing and other aquatic recreational activities are not met in the large tributaries upstream from Paris since the middle of the 1950's, and at least since the middle of the XIXth century in the main branch of the Seine river downstream from Paris. Efforts carried out for improving urban wastewater treatment in terms or organic matter and nutrient loading resulted in a sensible reduction of microbiological contamination, but were not specific enough toward bacteriological contamination for achieving the objective of restoring levels compatible with bathing activities in the Parisian area.
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fecal bacteria in the rivers of the seine Drainage Network france sources fate and modelling
Science of The Total Environment, 2007Co-Authors: Pierre Servais, Tamara Garciaarmisen, Isabelle George, Gilles BillenAbstract:The Seine river watershed (France) is a deeply anthropogenically impacted area, due to the high population density, intense industrial activities and intensive agriculture. The water quality and ecological functioning of the different rivers of the Seine Drainage Network have been extensively studied during the last fifteen years within the framework of a large French multidisciplinary scientific program (PIREN Seine program). This paper presents a synthesis of the main data gained in the scope of this program concerning the microbiological water contamination of the rivers of the Seine Drainage Network. The more common indicator of fecal contamination (fecal coliforms) was mainly used; some complementary works used E. coli and intestinal enterococci as alternative fecal indicators. Point sources (outfall of wastewater treatment plants) and non point sources (surface runoff and soil leaching) of fecal pollution to the rivers of the watershed were quantified. Results showed that, at the scale of a large urbanised watershed as the Seine basin, the input of fecal micro-organisms by non-point sources is much lower than the inputs by point sources. However, the local impact of diffuse non-human sources (especially surface runoff of pastured fields) can be of major importance on the microbiological quality of small headwater rivers. Fecal contamination of the main rivers of the Seine watershed (Seine, Marne, Oise rivers) was studied showing high level of microbiological pollution when compared to European guidelines for bathing waters. The strong negative impact of treated wastewater effluents outfall on the microbiological quality of receiving rivers was observed in different areas of the watershed. Once released in rivers, culturable fecal bacteria disappeared relatively rapidly due to mortality (protozoan grazing, lysis) or loss of culturability induced by stress conditions (sunlight effect, nutrient concentration, temperature). Mortality rates of E. coli were studied in different types of rivers within the watershed showing, in summer conditions, no major difference in the mortality rates in small and large rivers. As a result of these studies, a module describing the dynamics of fecal bacteria has been developed and embedded within a hydro-ecological model describing the functioning of the rivers of the whole watershed (the SENEQUE model). Once validated, such a model can be used for testing predictive scenarios and thus can be a very useful tool for the management of microbiological water quality at the scale of the whole basin.
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modeling nutrient n p si budget in the seine watershed application of the riverstrahler model using data from local to global scale resolution
Global Biogeochemical Cycles, 2005Co-Authors: Agata Sferratore, Gilles Billen, Josette Garnier, Sylvain TheryAbstract:[1] The deterministic Riverstrahler model that simulates nutrient transfer from land-based sources to the sea through the Drainage Network has been successfully applied to a number of large watersheds ranging from 20,000 to 800,000 km2. In order to assess the feasibility of upscaling such a model in view of its worldwide application based on global databases of hydrology, climate, population, land use, and lithology, a sensitivity analysis has been carried out. The response of the model to differing scales of input data, both high-resolution local data and low-resolution global data, is examined, applying the model to the well-documented Seine River basin. The results show that the evaluation of the overall annual fluxes of nutrients delivered at the outlet of a basin can be correctly predicted even from low resolution input data, provided that (1) the total discharge and seasonal hydrological regime are correctly simulated; (2) the Drainage Network description does not neglect tributaries that drain more than approximately 4000 km2 watershed area; and (3) the total point sources of nutrients as well as their distribution between the different stream orders are estimated (phosphorus being the most sensitive among the considered nutrients to point sources distribution). Diffuse sources of nutrients can be assessed from low-resolution land use and lithological data. As a result of this study, the capacity of statistical/empirical formulas to assess annual fluxes of nutrient delivery appears comparable to that of deterministic Drainage Network models, but the latter are particularly suited to predict seasonal variations of riverine nutrient delivery and its elemental ratios.
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nutrient fluxes and water quality in the Drainage Network of the scheldt basin over the last 50 years
Hydrobiologia, 2005Co-Authors: Gilles Billen, Josette Garnier, Veronique RousseauAbstract:and use and urban activity in the catchment of the Scheldt river system have deeply changed during the last 50 years, modifying in turn the water quality of the Drainage Network and the fluxes of nutrient transferred to the estuary and to the sea. Based on the RIVERSTRAHLER model, developed for establishing the link between the biogeochemical functioning of large river systems and the constraints set by the meteorology, the morphology of the Drainage Network and the human activity in the watershed, we reassembled the data available to document these constraints in the Scheldt basin since the last half of the XXth century and we used them to reconstruct the variations of nutrient and oxygen concentrations at the outlet of the Scheldt Drainage Network. We compared the results with the water quality data at the entrance of the estuarine zone available since the 1960s. Both model results and observational data show a very severe deterioration of water quality (with deep oxygen depletion) in the beginning of the 1960s, while a clear trend to improvement is apparent since the late 1980s. The budget of nutrient loadings from the watershed, retention within the Drainage Network and delivery to the estuarine zone is established on an annual basis for the 50 last years. The yearly fluxes of nutrient delivered by the river to the estuary and the sea show a severe depletion of silica with respect to nitrogen compared with the requirements of diatoms, and a clear shift from the early 1990s from nitrogen to phosphorus potential limitation. Seasonal variations of nutrient delivery are however much more pronounced for nitrogen, with much less inputs during the dry seasons, while phosphorus inputs, mainly from point sources are more constant, so that nitrogen limitation can still occur during summer. Compared with similar budget estimations carried out for the Seine river system, the Scheldt basin, in spite of its much higher population density, does not deliver higher specific fluxes of nutrient (presently about 2000 kgN/km2/yr, 80 kgP/km2/yr and 1000 kgSi/km2/yr), owing to very efficient processes of nutrient retention.
Lucia Struth - One of the best experts on this subject based on the ideXlab platform.
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quaternary Drainage Network reorganization in the colombian eastern cordillera plateau
Earth Surface Processes and Landforms, 2020Co-Authors: Lucia Struth, Emanuele Giachetta, Sean D Willett, Lewis A Owen, Eliseo TesonAbstract:This work was financed by the Spanish MINECO (Secretaria de Estado de Investigacion, Desarrollo e Innovacion) projects CGL2010-15416 and CGL2014-54180-P. L. Struth was supported by a FPI PhD grant (BES-2011-050262) from MECD (Spain). The stay at the University of Cincinnati for cosmogenic analysis was supported by MECD grant EEBB-I-14-08485. The authors acknowledge Mireia Domenech for her help in the field sampling. The authors thank Alan J. Hidy for his help and suggestions in the cosmogenic profile modeling. The authors are also grateful to Andres Mora and Andres Valencia for assistance and discussion during fieldwork.
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Drainage Network dynamics and knickpoint evolution in the ebro and duero basins from endorheism to exorheism
Geomorphology, 2019Co-Authors: Lucia Struth, Daniel Garciacastellanos, Marc Viaplanamuzas, Jaume VergesAbstract:Abstract The study of fluvial Network rearrangement provides a key to understand past and future landscape evolution. Large perturbations of hydrographic basins such as the change from endorheism to exorheism have repercussions in the steady or disequilibrium state of the basins and their Drainage divides. Such transitions from internal to external Drainage imply a major lowering of the geomorphological base level causing a major retreating knickpoint wave that separates the upstream low-relief area (inherited from the endorheic period) from the downstream incised area. Subsequently, the water divide migrates to reach an equilibrium in which erosion rates at both sides of the divide are similar. Previous fluvial analyses suggest that both the Duero and Ebro Drainage Networks, the two largest catchments in Iberia, experienced a change from endorheism to exorheism sometime between the Late Miocene and the Pliocene. Fluvial capture evidence argues for a Pliocene westward migration of the Ebro-Duero divide implying an area decrease for the Duero fluvial Network (victim) in favor of the Ebro (aggressor). We used river profiles, knickpoint distribution and Chi-map calculation to understand the different degree of erosion of the Duero and the Ebro catchments and the dynamics of their Drainage Network. The results show an equilibrated Ebro Drainage Network in contrast with a disequilibrium in the erosional state of the Duero Drainage, which remains reorganizing and adapting to the newly-imposed Atlantic base level. We identified at least two knickpoint wave trains in the Duero Drainage resulting from the onset of exorheism: a fast-propagating wave through the cover and a low-propagating wave affecting the bedrock. Field evidence and topographic analysis suggest a westward migration of the Ebro-Duero divide, resulting in an ongoing headward erosion of the Ebro against the Duero catchment. Chi analysis provides the degree of disequilibrium of the Drainage Network indicating a large-scale aggressor role for the Duero and a victim role for the Ebro. We interpreted this seeming contradiction as the result of a different time scale perspective: local divide observations indicate a victim Duero in the short-term, whereas basin-scale dynamics support a victim role for the Ebro fluvial Network in the long-term (multi-million-year time-scales).
P La Barbera - One of the best experts on this subject based on the ideXlab platform.
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the impact of domestic rainwater harvesting systems in storm water runoff mitigation at the urban block scale
Journal of Environmental Management, 2017Co-Authors: Anna Palla, I Gnecco, P La BarberaAbstract:Abstract In the framework of storm water management, Domestic Rainwater Harvesting (DRWH) systems are recently recognized as source control solutions according to LID principles. In order to assess the impact of these systems in storm water runoff control, a simple methodological approach is proposed. The hydrologic-hydraulic modelling is undertaken using EPA SWMM; the DRWH is implemented in the model by using a storage unit linked to the building water supply system and to the Drainage Network. The proposed methodology has been implemented for a residential urban block located in Genoa (Italy). Continuous simulations are performed by using the high-resolution rainfall data series for the ‘‘do nothing’’ and DRWH scenarios. The latter includes the installation of a DRWH system for each building of the urban block. Referring to the test site, the peak and volume reduction rate evaluated for the 2125 rainfall events are respectively equal to 33 and 26 percent, on average (with maximum values of 65 percent for peak and 51 percent for volume). In general, the adopted methodology indicates that the hydrologic performance of the storm water Drainage Network equipped with DRWH systems is noticeable even for the design storm event (T = 10 years) and the rainfall depth seems to affect the hydrologic performance at least when the total depth exceeds 20 mm.
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the impact of domestic rainwater harvesting systems in storm water runoff mitigation at the urban block scale
Journal of Environmental Management, 2017Co-Authors: Anna Palla, I Gnecco, P La BarberaAbstract:Abstract In the framework of storm water management, Domestic Rainwater Harvesting (DRWH) systems are recently recognized as source control solutions according to LID principles. In order to assess the impact of these systems in storm water runoff control, a simple methodological approach is proposed. The hydrologic-hydraulic modelling is undertaken using EPA SWMM; the DRWH is implemented in the model by using a storage unit linked to the building water supply system and to the Drainage Network. The proposed methodology has been implemented for a residential urban block located in Genoa (Italy). Continuous simulations are performed by using the high-resolution rainfall data series for the ‘‘do nothing’’ and DRWH scenarios. The latter includes the installation of a DRWH system for each building of the urban block. Referring to the test site, the peak and volume reduction rate evaluated for the 2125 rainfall events are respectively equal to 33 and 26 percent, on average (with maximum values of 65 percent for peak and 51 percent for volume). In general, the adopted methodology indicates that the hydrologic performance of the storm water Drainage Network equipped with DRWH systems is noticeable even for the design storm event (T = 10 years) and the rainfall depth seems to affect the hydrologic performance at least when the total depth exceeds 20 mm.
Shane Feirer - One of the best experts on this subject based on the ideXlab platform.
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cumulative impacts of residential rainwater harvesting on stormwater discharge through a peri urban Drainage Network
Journal of Environmental Management, 2019Co-Authors: Matthew J Deitch, Shane FeirerAbstract:Green infrastructure and techniques such as rainwater harvesting have been proposed as a means to reduce stormwater discharge in developed areas prone to floods. We examined the effects of rainwater harvesting on discharge cumulatively through the Perdido River Drainage Network in the US state of Florida, an area prone to routine rainfall-driven nuisance flooding. We considered scenarios where rainwater is stored in parcels with structures that use septic tanks (where tanks are retired and used as cisterns, volume approximately 5.7 cubic meters); and where a similar volume of water is stored at all developed parcels. To evaluate flow reduction through the Drainage Network, we modeled effects relative to a flow event with a 1.5-year recurrence interval using a spatial GIS-based cumulative-effects model. Our model predicted that retired septic tanks would reduce discharge by more than 10 percent in only a few areas in the study region, almost exclusively in headwater regions and where density of houses using septic tanks is high. Analysis of all developed parcels storing rainwater indicated that discharge in several areas would be reduced by more than 20 percent. Results indicate a spatially variable potential for rainwater harvesting to reduce routine storm discharge. Spatially continuous hydrologic tools such as the one we use here may be especially useful for managers seeking to prioritize limited resources at locations for maximum benefit.
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cumulative effects of small reservoirs on streamflow in northern coastal california catchments
Water Resources Management, 2013Co-Authors: Matthew J Deitch, Adina M Merenlender, Shane FeirerAbstract:With small reservoirs increasingly employed to meet human water needs, tools that consider cumulative effects of multiple small reservoirs through space and time are essential for understanding impacts of these spatially distributed stresses on catchment hydrology and related ecological processes. We used a GIS-based hydrologic model to predict streamflow impairment caused by 438 small reservoirs in a 743 km2 study area in Sonoma County, California, USA. The GIS model was designed to consider the varying effects that these reservoirs have through the project area Drainage Network, as well as the varying effects they have over time (as reservoirs fill and no longer impair flow downstream). Results indicate that, at the onset of the water year (when reservoirs are assumed to be empty), more than 25 % of the Drainage Network below reservoirs is impaired by over 50 %. Nine weeks into a normal-type water year, approximately 25 % of the Drainage Network below reservoirs is impaired by at least 25 %; and at 15 weeks, five percent of the Drainage below reservoirs is impaired at least 25 %. Impairment is more persistent in a dry-type year. Nine weeks into a dry year, almost 40 % of the Drainage Network below reservoirs is impaired by at least 25 %; and at 15 weeks, 25 % of the Drainage is impaired by at least 25 %. Results illustrate that impairment caused by reservoirs varies appreciably over space, but as reservoirs fill over time, impairment is lower through most of the Drainage Network.
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cumulative effects of small reservoirs on streamflow in northern coastal california catchments
Water Resources Management, 2013Co-Authors: Matthew J Deitch, Adina M Merenlender, Shane FeirerAbstract:With small reservoirs increasingly employed to meet human water needs, tools that consider cumulative effects of multiple small reservoirs through space and time are essential for understanding impacts of these spatially distributed stresses on catchment hydrology and related ecological processes. We used a GIS-based hydrologic model to predict streamflow impairment caused by 438 small reservoirs in a 743 km 2 study area in Sonoma County, California, USA. The GIS model was designed to consider the varying effects that these reservoirs have through the project area Drainage Network, as well as the varying effects they have over time (as reservoirs fill and no longer impair flow downstream). Results indicate that, at the onset of the water year (when reservoirs are assumed to be empty), more than 25 % of the Drainage Network below reservoirs is impaired by over 50 %. Nine weeks into a normal-type water year, approximately 25 % of the Drainage Network below reservoirs is impaired by at least 25 %; and at 15 weeks, five percent of the Drainage below reservoirs is impaired at least 25 %. Impairment is more persistent in a dry-type year. Nine weeks into a dry year, almost 40 % of the Drainage Network below reservoirs is impaired by at least 25 %; and at 15 weeks, 25 % of the Drainage is impaired by at least 25 %. Results illustrate that impairment caused by reservoirs varies appreciably over space, but as reservoirs fill over time, impairment is lower through most of the Drainage Network. Copyright Springer Science+Business Media Dordrecht 2013
Pierre Servais - One of the best experts on this subject based on the ideXlab platform.
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modelling faecal contamination in the scheldt Drainage Network
Journal of Marine Systems, 2013Co-Authors: Nouho Koffi Ouattara, Anouk De Brauwere, Gilles Billen, Pierre ServaisAbstract:This study developed a model simulating the seasonal and spatial variations of microbiological water quality (expressed in terms of Escherichia coli concentrations) in rivers. The model (SENEQUE-EC) consists of a microbiological module appended to a hydro-ecological model describing the functioning of the entire Scheldt Drainage Network. The microbiological module describes the sources of E. coli, their transport and the processes responsible for the fate of E. coli once released into the natural environment (mortality, settling and resuspension). This model differentiates the dynamics of three types of E. coli: free-floating E. coli, E. coli attached to suspended solids in the water column and E. coli present in sediments. The model was verified by comparison of its results with temporal and spatial distributions of field data in different stretches of rivers of the Scheldt Drainage Network. It was then used to test various scenarios involving diverse modifications in wastewater management, which was shown to be the most determining factor of microbiological water quality. Due to its low temporal resolution, the SENEQUE-EC is poorly adapted to describing the microbiological quality in areas under tidal influence. Therefore, the data of the SENEQUE-EC model were used as upstream boundary conditions to run a microbiological model with a high temporal resolution devoted to the tidal Scheldt River and Estuary (the SLIM-EC2 model).
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faecal contamination of water and sediment in the rivers of the scheldt Drainage Network
Environmental Monitoring and Assessment, 2011Co-Authors: Nouho Koffi Ouattara, Julien Passerat, Pierre ServaisAbstract:The Scheldt watershed is characterized by a high population density, intense industrial activities and intensive agriculture and breeding. A monthly monitoring (n = 16) of the abundance of two faecal indicator bacteria (FIB), Escherichia coli and intestinal enterococci (IE), showed that microbiological water quality of the main rivers of the Scheldt Drainage Network was poor (median values ranging between 1.4 × 103 and 4.0 × 105 E. coli (100 mL) − 1 and between 3.4 × 102 and 7.6 × 104 IE (100 mL) − 1). The Zenne River downstream from Brussels was particularly contaminated. Glucuronidase activity was measured in parallel and was demonstrated to be a valid surrogate for a rapid evaluation of E. coli concentration in the river waters. FIB were also investigated in the river sediments; their abundance was sometimes high (average values ranging between 2.1 × 102 and 3.3 × 105 E. coli g − 1 and between 1.0 × 102 and 1.7 × 105 IE g − 1) but was not sufficient to contribute significantly to the river water contamination during resuspension events, except for the Scheldt and the Nethe Rivers. FIB were also quantified in representative point sources (wastewater treatment plants) and non-point sources (runoff water and soil leaching on different types of land use) of faecal contamination. The comparison of the respective contribution of point and non-point sources at the scale of the Scheldt watershed showed that point sources were largely predominant.
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fecal bacteria in the rivers of the seine Drainage Network france sources fate and modelling
Science of The Total Environment, 2007Co-Authors: Pierre Servais, Tamara Garciaarmisen, Isabelle George, Gilles BillenAbstract:The Seine river watershed (France) is a deeply anthropogenically impacted area, due to the high population density, intense industrial activities and intensive agriculture. The water quality and ecological functioning of the different rivers of the Seine Drainage Network have been extensively studied during the last fifteen years within the framework of a large French multidisciplinary scientific program (PIREN Seine program). This paper presents a synthesis of the main data gained in the scope of this program concerning the microbiological water contamination of the rivers of the Seine Drainage Network. The more common indicator of fecal contamination (fecal coliforms) was mainly used; some complementary works used E. coli and intestinal enterococci as alternative fecal indicators. Point sources (outfall of wastewater treatment plants) and non point sources (surface runoff and soil leaching) of fecal pollution to the rivers of the watershed were quantified. Results showed that, at the scale of a large urbanised watershed as the Seine basin, the input of fecal micro-organisms by non-point sources is much lower than the inputs by point sources. However, the local impact of diffuse non-human sources (especially surface runoff of pastured fields) can be of major importance on the microbiological quality of small headwater rivers. Fecal contamination of the main rivers of the Seine watershed (Seine, Marne, Oise rivers) was studied showing high level of microbiological pollution when compared to European guidelines for bathing waters. The strong negative impact of treated wastewater effluents outfall on the microbiological quality of receiving rivers was observed in different areas of the watershed. Once released in rivers, culturable fecal bacteria disappeared relatively rapidly due to mortality (protozoan grazing, lysis) or loss of culturability induced by stress conditions (sunlight effect, nutrient concentration, temperature). Mortality rates of E. coli were studied in different types of rivers within the watershed showing, in summer conditions, no major difference in the mortality rates in small and large rivers. As a result of these studies, a module describing the dynamics of fecal bacteria has been developed and embedded within a hydro-ecological model describing the functioning of the rivers of the whole watershed (the SENEQUE model). Once validated, such a model can be used for testing predictive scenarios and thus can be a very useful tool for the management of microbiological water quality at the scale of the whole basin.
