Modélisation du transfert des nitrates dans un système hydrologique

Modeling nitrate transfers in hydrological systems

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Abstract

This paper presents a methodology for modeling the transfer, and particularly the leaching of nitrates in a hydrological system such as regional basin. A model of production and leaching of nitrates, called MORELN, was built in order to calculate the nitrates flux percolating from soil into groundwater. It uses the "Coupled Model", which simulates integrally the surface and groundwater flows, as the water transfer model. A third model, NEWSAM was employed for modeling the nitrates migration in the aquifer system. The jointed use of these three models gives a global description of the nitrates transfer taking into account both the nitrates production in soils and their displacement in aquifers. Three examples of application allowed us to test this methodology, and especially the MORELN model, on three different scales: in a lysimeter of several m², in a small experimental basin of several km² and finally in a regional hydrological system of sevral hundreds km²