Turbidity and nitrate transfer in karstic aquifers in rural areas: the Brionne Basin case-study.
The degradation of water quality in many groundwaters of Europe is a major source of concern. Rises in turbidity and nitrate concentrations represent present or potential threats for the quality of drinking water in rural areas. They are for the most part a consequence of agricultural intensification which has considerably affected land cover and land use in recent decades. In our case-study (a karstic catchment) the mechanisms which explain changes in water quality, as far as turbidity and nitrate are concerned, result from a strong continuity between surface and underground waters. The karstic system of the Brionne Basin can be considered as both the focus of rapid horizontal flows (runoff, a rapid process in which rainwater reaches the spring directly through sinkholes) and slow vertical flows (leaching, in which rainwater filters through the soil to the spring). A hierarchical approach to the water pollution problem of the basin suggests that turbidity or nitrate concentrations peak during heavy rain episodes and are short-term events. In terms of management, this implies that the solution to water pollution caused by such events is also short-term and can therefore be addressed at a local scale. The rise of nitrate concentrations during the past twenty years is the main concern. The solution can only be found at a global scale (all the catchment area must be taken in account: land plots and their spatial configuration), and by taking a long-term approach.
Nebbache
S
S
Laboratoire d'Ecologie Université de Rouen, UPRES-EA 1293, 76821 Mont Saint Algnan, France.
Feeny
V
V
Poudevigne
I
I
Alard
D
D
D000383:Agriculture; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D009566:Nitrates / Q000737:chemistry*; D011891:Rain; D012989:Soil Pollutants; D014872:Water Movements; D014873:Water Pollutants; D014881:Water Supply
D009566:Nitrates; D012989:Soil Pollutants; D014873:Water Pollutants