Laboratoire d’étude des Transferts en Hydrologie et Environnement
Grenoble, France
Description
Water and soil resources management and hydrometeorological hazard mitigation are critical issues in mountainous regions, especially those of the Mediterranean edge due to on-going climate change and increased anthropic pressure. Studies, coupling the methodological approaches of hydrometeorology, hydrology and soil sciences, are required to observe and understand the processes and establish hydrosedimentary balances over a range of nested spatial scales, from the hillslope up to medium-scale watersheds (100 – 1000 km²). The PhD thesis will focus on the relationships between the spatial and temporal variability of rainfall in mountainous regions, and the subsequent flash-floods and suspended solids transfers (SST) over nested watersheds in the Ardèche region, France. The objectives are to (1) characterize the fine scale variability of heavy rainfall (5 min, <1 km² typically) and (2) to observe and model the resulting non-linear hydro-sedimentary response. In addition to the operational rainfall observation system (weather radars and raingauge networks of Météo France and the Service de Prévision des Crues du Grand Delta), an X-band Doppler polarimetric radar, well suited to rainfall measurement in mountainous regions, will be available together with a dense network of raingauges and disdrometers. Emphasis will be placed in the thesis on the production of rainfall re-analyzes, temporally continuous with very high resolution for the most intense episodes. An error model will be specified to allow the generation of probabilistic quantitative precipitation estimates. Water flows and SST will be measured continuously at the outlet of the nested watersheds of Gazel (3.4 km2), Claduègne (43 km2) and Auzon (116 km2). In parallel, monitoring a network of limnimeters in the intermittent drainage basins upstream will allow to document the hydrologic response of sample of landscapes (lithology, soil type, vegetation cover, elevation, land use, etc..). Moreover innovative observation techniques of river flows (LSPIV, radar) will be implemented during floods and high resolution LIDAR data will be available in order to characterize the topography and the drainage network. An essential part of the thesis will be devoted to the implementation and development of the DHSVM model (Distributed Hydrology Soil Vegetation atmosphere Model) to understand, using the collected data, the functioning of the watersheds and assess the sensitivity of the spatial-temporal variability of rainfall on the dynamics of water flow and SST. We also plan to work on matching the rainfall spatial resolution and the watersheds spatial discretization in the DHSVM model to optimize the number of soil and erosion parameters and / or to propose new parameterization schemes of the runoff and erosion production at fine scales.
Requirements
The candidate must have a solid educational background in physics applied to the environment and in particular have followed specialized courses in hydrometeorology, hydrology and soil science. Very good skills in scientific computing and numerical methods are required: FORTRAN and / or C, R and / or MATLAB, optional experience in Geographic Information System. The supervisors also attach great importance to good writing skills. A good command of French and / or English is important, as well as the ability of organization and synthesis, autonomy and the taste of team
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