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See detailAléa climatique et débits des cours d’eau dans le bassin transnational de la Meuse : Co-variabilité, changements possibles et impact sur les débordements
Grelier, Benjamin ULiege

Doctoral thesis (2017)

Climate change is a global socio-environmental concern which required adaptation from human societies in order to compensate negative effects and to take benefit from positive effects. Our research is ... [more ▼]

Climate change is a global socio-environmental concern which required adaptation from human societies in order to compensate negative effects and to take benefit from positive effects. Our research is studying water cycle at the catchment scale and contribute to the adaptation of the transnational Meuse basin to the effects of climate change on hydrological extremes (floods and low flows). To this aim, we adopted a hazard-centered approach. A top-down modelling chain has been set up on two contrasted sub-basins of the Meuse river: the Meuse river at Saint-Mihiel (2543 km², France) and the Ourthe river at Tabreux (1607 km², Belgium). The climate forcing of the chain is constructed on a temporal continuum ranging from the Maunder Minimum (≈ 1650 A.D.) to the end of the 21st century. For the future, climate data are provided by an ensemble of GCMs run in the framework of the Coupled Model Intercomparison Project Phase 5 (CMIP5) and forced with RCP radiative scenarios. For the historical period, gridded data available in the study area are used. Blending past and future climate data is obtained through a transfer function, linking the pressure gradient force to climate forcing variables of catchment streamflow (i.e. atmospheric water and energy supplies). Aggregation of climate data provides a first estimation of potential climatic variability for the two studied sub-basins. The hydrological effect of this potential climatic variability is evaluated in two ways: i) through a regression climate-streamflow transfer function which predicts the streamflow at the outlet of a catchment with the information provided by the pressure gradient force. Regression models are fitted in present climate conditions and used further to extrapolate the streamflow at the outlet of a catchment with CMIP5 GCMs data; ii) through the link between the pressure gradient force and climate forcing variables of streamflow. Regression models are efficient enough to provide robust estimation of the potential climate variability at the scale of interest. The delta-change approach is then applied to potential climate variability to get representative climate scenarios at a daily time step relevant for rainfall-runoff modelling. The tested rainfall-runoff model (GR4J) is calibrated through a climatically robust method. This step gives a first estimation of the two sub-basins sensibility to prescribed climate changes. In order to evaluate the effect of climate change on hydraulic behavior of a river, the modelling chain has been completed with the WOLF1D hydraulic model. Is has been parameterized and validated for a section of the Ourthe river. Boundary conditions were forced with representative climate scenarios to evaluate the climate change effect on overflowing. In a first step, the latter is characterized through overflowing sequences determined through simulated water levels. Then, to overcome the limits of the WOLF1D model in flood-prone area, the flow-duration-frequency behavior of the first overflowing streamflow is studied to show the overflowing evolution under climate change. In the end, our work provides an original framework for studying climate change effect on hydrological extremes through a sampling of climate changes with past and future climate series. The use of a hazard-centered modelling chain is a first step toward adaptation strategies suited for contrasted climate conditions. This contributes in turn to make catchment more resilient. [less ▲]

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See detailCOMMENT INTRODUIRE DE LA « BONNE » INCERTITUDE DANS LES PROJECTIONS CLIMATIQUES ? VERS LA CONSTRUCTION D’UN « STRESS-TEST » CLIMATIQUE DANS LE BASSIN TRANSNATIONAL DE LA MEUSE.
Grelier, Benjamin ULiege; Drogue, Gilles

in Erpicum, Michel (Ed.) Modélisation & Variabilités (2015)

Past analysis of climate variability is useful to maximize the good uncertainty when producing future climate projections. This paper presents the application of a simple method linking atmospheric ... [more ▼]

Past analysis of climate variability is useful to maximize the good uncertainty when producing future climate projections. This paper presents the application of a simple method linking atmospheric circulation and surface climatic variables with the aim to extrapolate knowledge of climate in the past (until the Maunder minimum) and in the near future (21st century). This allows building a lot of plausible climatic scenarios, which form the basis of a climate “stress-test”. Its objective is to assess the hydrologic vulnerability of a catchment to the climate change. Calculated on the whole period of interest (1659-2100), monthly precipitation and temperature anomalies show that the knowledge of past climate has a high informative value, which is not enough taken into account in the climate change impact studies. [less ▲]

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