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Modélisation des transferts de nitrates, confrontation des concepts, des données et des informations : application au bassin de la Charente

Abstract : The aim of this work is focused on the simulation of nitrate concentration at the outlet of rural watersheds. The main objective of this research is to model the transfer of nitrates at various catchment scales. A daily semi-distributed model has been elaborated and tested on Charente sub-catchments (France). An hydrological conceptual model (GR3) has been chosen and adapted to model the transfer of nitrates. The conceptual leaching model is closely linked with the rainfall-runoff model both by hydrological variables and model parameters. The different constituents of the model and its parameters are taken from literature or from measurement or calibrated against data. Principal processes used in modelling are dilution of fertilisers and animal faeces, uptake by plants, chemical, physical and biological transformations in soil and river denitrification. The model was calibrated on a few years, on sub-catchments where runoff and concentration are known for 15 years. Afterwards, the model has been used with average or regionalized parameters on sub-catchments where only one of these variables is known and on basins where there are no data. The final model has been applied on the Charente basin (9500 km2) and on intermediary quality stations, and on the representative and experimental sub-catchment of the Ruiné river (5,5 km2). Results show that our model reproduces correctly general trend of nitrate load to the Marennes-Oléron bay. Seasonal variations of nitrates concentration are well respected on most of the stations. However, a few simulated values are not in good agreement with the measurements. Also, we studied the behaviour of nitrates concentration during floods. We observed the same figures of hysteresis in the runoff-concentration relationship as observed on suspended sediments. These observations showed the complexity of leaching and transfer phenomena on this sub-catchment.
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Submitted on : Friday, February 25, 2011 - 9:29:45 AM
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  • HAL Id : pastel-00569426, version 1



Gabriela Mantilla Morales. Modélisation des transferts de nitrates, confrontation des concepts, des données et des informations : application au bassin de la Charente. Hydrologie. Ecole Nationale des Ponts et Chaussées, 1995. Français. ⟨pastel-00569426⟩



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