Modeling Flow and Nitrate Fate at Catchment Scale in Brittany (France)
- Céline Conan *a,
- Fayçal Bouraouia,
- Nadine Turpinb,
- Ghislain de Marsilyc and
- Giovanni Bidoglioa
- a Joint Research Centre of the European Commission, Inst. for Environment and Sustainability, Soil and Waste Unit, TP 460, 21020 Ispra (VA), Italy
b Cemagref Rennes, URE Gere, 17 avenue de Cucillé, 35044 Rennes Cedex, France
c Laboratory of Applied Geology, Univ. of Paris 6, T.26-0 E.5 case 123, 4, place Jussieu, 75252 Paris Cedex 05, France
In the intensive pig-farming (Sus scrofa) area of Brittany (western France), many surface and subsurface water resources are contaminated by nitrate (NO3) with concentrations that chronically exceed the European Community 50 mg L−1 drinking standard. To ensure sustainable water supply, the fate of NO3 must be considered in both surface water and ground water. The fate of N was investigated in a Britain catchment, the Coët-Dan watershed, with an integrated management tool: the hydrological SWAT model coupled with the ground water model MODFLOW, and its companion contaminant and solute transport model MT3DMS. The model was validated with respect to water quantity during a 6-yr period and for the NO3 concentration during a 44-mo period, at two gauging stations in the catchment. The coupled models reproduced accurately the measurements. At the basin outlet, the Nash-Sutcliffe coefficients were 0.88 for monthly flow for the entire period and 0.87 for monthly N load. Alternative scenarios were simulated and showed potential benefits of decreasing manure application from 210 to 170 kg N ha−1 as required by the European Commission Nitrates Directive.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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