Murviel-lès-Montpellier, France
Murviel-lès-Montpellier, France

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Ruelland D.,French National Center for Scientific Research | Larrat V.,IRD Montpellier | Guinot V.,UM2 UMR HydroSciences Montpellier
IAHS-AISH Publication | Year: 2010

Environmental and climatic changes have occurred in western African regions over many decades. These changes, which are variable in space and time, can have lasting effects on water resources. Hydrological modelling can help to assess the impact of these changes by representing the processes governing the relationship between climatic data and river flow regimes. This paper compares two reservoir-based hydrological models (HydroStrahler and GR4J) operating on a daily time step. The models are tested over an approx. 50-year period in a large, poorly gauged Sudano-Sahelian catchment that has undergone significant hydro-climatic variability. A calibration/validation exercise is performed using lumped and semi-distributed approaches. The simulations are compared via a multicriteria analysis based on a variety of goodness-of-fit indices. Both models simulate the rainfall-runoff relationship over the catchment area with a fair degree of realism. Given the calibration strategy, the flood dynamics are better reproduced using the HydroStrahler model, while the GR4J model gives a more accurate estimate of cumulated discharge. The semi-distributed approach allows for a better representation of the hydrological processes within the watershed, which does not necessarily lead to improved outlet simulations compared to the lumped approach. A sensitivity analysis of the parameters also shows that equifinality problems are reduced when the calibration is considered within a multiobjective framework. Furthermore, the robustness of the simulations indicates that the models can be applied to various climatic conditions. The performance indexes prove satisfactory in validation periods containing either wet or dry spells. As a result, these models can be used to forecast future water availability using mid-term climatic scenarios in the basin. Copyright © 2010 IAHS Press.


Collet L.,UM2 UMR HydroSciences Montpellier | Ruelland D.,French National Center for Scientific Research | Borrell-Estupina V.,UM2 UMR HydroSciences Montpellier | Dezetter A.,IRD Montpellier | Servat E.,IRD Montpellier
Science of the Total Environment | Year: 2013

Assessing water supply capacity is crucial to meet stakeholders' needs, notably in the Mediterranean region. This region has been identified as a climate change hot spot, and as a region where water demand is continuously increasing due to population growth and the expansion of irrigated areas. The Hérault River catchment (2500km2, France) is a typical example and a negative trend in discharge has been observed since the 1960s. In this context, local stakeholders need first to understand the processes controlling the evolution of water resources and demands in the past to latter evaluate future water supply capacity and anticipate the tensions users could be confronted to in the future. A modelling framework is proposed at a 10-day time step to assess whether water resources have been able to meet water demands over the last 50years. Water supply was evaluated using hydrological modelling and a dam management model. Water demand dynamics were estimated for the domestic and agricultural sectors. A water supply capacity index is computed to assess the extent and the frequency to which water demand has been satisfied at the sub-basin scale. Simulated runoff dynamics were in good agreement with observations over the calibration and validation periods. Domestic water demand has increased considerably since the 1980s and is characterized by a seasonal peak in summer. Agricultural demand has increased in the downstream sub-basins and decreased upstream where irrigated areas have decreased. As a result, although most water demands were satisfied between 1961 and 1980, irrigation requirements in summer have sometimes not been satisfied since the 1980s. This work is the first step toward evaluating possible future changes in water allocation capacity in the catchment, using future climate change, dam management and water use scenarios. © 2013 Elsevier B.V.


Borrell-Estupina V.,UM2 UMR HydroSciences Montpellier | Ladouche B.,Bureau de Recherches Géologiques et Minières | Malaterre P.-O.,IRSTEA | Ricci S.,European Center for Research and Advanced Training in Scientific Computation | And 7 more authors.
IAHS-AISH Proceedings and Reports | Year: 2014

Extreme rainfall on Mediterranean karstic watersheds can lead to flash floods that may cause serious human and material losses. The anticipation of these events and the risk management during flood events are at the core of society and financial stakes. Karstic aquifers should also be considered as valuable groundwater resources. An active management of these aquifers may allow for an optimal use of water resources, while regulating the influence of the karst during flood risk periods. This study was carried out in the framework of the "Multiple-Use Management of the Mediterranean Karstic Aquifer of the Lez River" project. It aimed at identifying the impact of the anthropic management of the water resource and floods under the present and future climate on the catchment. This project led to building a graphical method (toolbox for flood management presented as an abacus) for (i) a better understanding of the evolution of the water volume of the karstic system, the river discharge and the propagation of floods through constructed infrastructure of the river in urban areas, (ii) real-time flood forecasting, and (iii) analysing the impact of climate projections and active management scenarios with respect to the water in the karstic system as well as with respect to the flooding areas. The use of active management is thus shown to increase the availability of water resources while reducing flood risks. © Copyright 2014 IAHS Press.


Ruelland D.,French National Center for Scientific Research | Ardoin-Bardin S.,IRD Montpellier | Collet L.,UM2 UMR HydroSciences Montpellier | Roucou P.,University of Burgundy
Journal of Hydrology | Year: 2012

This paper assesses the future variability of water resources in the short, medium and long terms over a large Sudano-Sahelian catchment in West Africa. Flow simulations were performed with a daily conceptual model. A period of nearly 50. years (1952-2000) was chosen to capture long-term hydro-climatic variability. Calibration and validation were performed on the basis of a multi-objective function that aggregates a variety of goodness-of-fit indices. The climate models HadCM3 and MPI-M under SRES-A2 were used to provide future climate scenarios over the catchment. Outputs from these models were used to generate daily rainfall and temperature series for the 21st century according to: (i) the unbias and delta methods application and (ii) spatial and temporal downscaling. A temperature-based formula was used to calculate present and future potential evapotranspiration (PET). The daily rainfall and PET series were introduced into the calibrated and validated hydrological model to simulate future discharge. The model correctly reproduces the observed discharge at the basin outlet. The Nash-Sutcliffe efficiency criterion is over 89% for both calibration and validation periods, and the volume error between simulation and observation is close to null for the overall considered period. With regard to future climate, the results show clear trends of reduced rainfall over the catchment. This rainfall deficit, together with a continuing increase in potential evapotranspiration, suggests that runoff from the basin could be substantially reduced, especially in the long term (60-65%), compared to the 1961-1990 reference period. As a result, the long-term hydrological simulations show that the catchment discharge could decrease to the same levels as those observed during the severe drought of the 1980s. © 2012 Elsevier B.V.


Ruelland D.,French National Center for Scientific Research | Brisset N.,UM2 UMR HydroSciences Montpellier | Jourde H.,UM2 UMR HydroSciences Montpellier | Jourde H.,University of La Serena | Oyarzun R.,University of La Serena
IAHS-AISH Publication | Year: 2011

This study aims to simulate the relationship between climate forcing and the dynamics of both water table levels and runoff from the upper Elqui catchment (5660 km 2, Chile). Simulations are performed with a daily conceptual model that takes into account: (i) a shallow reservoir supplied by precipitation and feeding evapotranspiration, surface/sub-surface runoff and infiltration, and (ii) a deep reservoir fed by infiltration and generating the baseflow. A third reservoir, in which fluxes are controlled by temperature, has been introduced to account for the snowmelt regime of the catchment. A nearly 30-year period (1977-2008) was chosen to capture long-term hydro-climatic variability due to alternating ENSO and LNSO events. Calibration and validation were performed on the basis of a multi-objective function that aggregates a variety of goodness-of-fit criteria. The model correctly reproduces the observed discharge at the basin outlet, for either lumped or semi-distributed applications. Nash coefficients are about 0.9 over the calibration period (1979-1990) and 0.75 over the validation period (1991-2008). The volume error between observation and simulation is lower than 11% over the whole period studied. The dynamics of both the water level in the deep conceptual reservoir and the water table in a piezometer at the basin outlet are also in good agreement. The model thus provides encouraging simulations of groundwater and surface flows when applied to various climatic conditions. However, improvements are still needed before forecasting water availability using medium-term climatic scenarios. Copyright © 2011 IAHS Press.


Collet L.,UM2 UMR HydroSciences Montpellier | Ruelland D.,French National Center for Scientific Research | Borrell-Estupina V.,UM2 UMR HydroSciences Montpellier | Servat E.,IRD Montpellier
Hydrological Sciences Journal | Year: 2014

This article addresses the critical need for a better quantitative understanding of how water resources from the Hérault River catchment in France have been influenced by climate variability and the increasing pressure of human activity over the last 50 years. A method is proposed for assessing the relative impacts of climate and growing water demand on the decrease in discharge observed at various gauging stations in the periods 1961-1980 and 1981-2010. An annual water balance at the basin scale was calculated first, taking into account precipitation, actual evapotranspiration, water withdrawals and water discharge. Next, the evolution of the seasonal variability in hydroclimatic conditions and water withdrawals was studied. The catchment was then divided into zones according to the main geographical characteristics to investigate the heterogeneity of the climatic and human dynamics. This delimitation took into account the distribution of climate, topography, lithology, land cover and water uses, as well as the availability of discharge series. At the area scale, annual water balances were calculated to understand the internal changes that occurred in the catchment between both past periods. The decrease in runoff can be explained by the decrease in winter precipitation in the upstream areas and by the increase during summer in both water withdrawals and evapotranspiration in the downstream areas, mainly due to the increase in temperature. Thus, water stress increased in summer by 35%. This work is the first step of a larger research project to assess possible future changes in the capacity to satisfy water demand in the Hérault River catchment, using a model that combines hydrological processes and water demand. © 2014 © 2014 IAHS Press.


PubMed | UM2 UMR HydroSciences Montpellier
Type: | Journal: The Science of the total environment | Year: 2013

Assessing water supply capacity is crucial to meet stakeholders needs, notably in the Mediterranean region. This region has been identified as a climate change hot spot, and as a region where water demand is continuously increasing due to population growth and the expansion of irrigated areas. The Hrault River catchment (2500 km(2), France) is a typical example and a negative trend in discharge has been observed since the 1960s. In this context, local stakeholders need first to understand the processes controlling the evolution of water resources and demands in the past to latter evaluate future water supply capacity and anticipate the tensions users could be confronted to in the future. A modelling framework is proposed at a 10-day time step to assess whether water resources have been able to meet water demands over the last 50 years. Water supply was evaluated using hydrological modelling and a dam management model. Water demand dynamics were estimated for the domestic and agricultural sectors. A water supply capacity index is computed to assess the extent and the frequency to which water demand has been satisfied at the sub-basin scale. Simulated runoff dynamics were in good agreement with observations over the calibration and validation periods. Domestic water demand has increased considerably since the 1980s and is characterized by a seasonal peak in summer. Agricultural demand has increased in the downstream sub-basins and decreased upstream where irrigated areas have decreased. As a result, although most water demands were satisfied between 1961 and 1980, irrigation requirements in summer have sometimes not been satisfied since the 1980s. This work is the first step toward evaluating possible future changes in water allocation capacity in the catchment, using future climate change, dam management and water use scenarios.

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