Quelle réponse de l'agriculture face aux sécheresses exceptionnelles ? Itude de l'impact de la mise en place des lacs collinaires dans le bassin versant du Lemboulas (Bas-Quercy, Midi-Pyrénées)

Abstract

The watershed of Lemboulas (400 km2) is located in the north of the Tarn et Garonne (Midi Pyrénées). It is a région of hills, with a strong presence of farming (polyculture, 1240 operating in the municipalities concerned). This basin, which is regulary subjected to summer droughts leading to significant restrictions on pumping in river is particularly interesting. Farmers, for thirty years have created more than 360 ponds. This study is based on data from interviews with farmers, and analysis of statistical data (measured flow of Lemboulas, local temperatures ond rainfull). It intends to answer the question of the influence of periods of exceptional drought in the practices of farmers. The years of drought selected for the study are: 1976, 1989 to 1991 and 2003. They ingrained in the minds of farmers by their importance and are found in the statistical series of meteorology. Be limited to a relatively small watershed, and dominated by mixed farming is a strategic choice: it allows viewing on a small area of many practices, cultures, methods. The results could provide working hypotheses for further investigation. © 2010 Société Hydrotechnique de France.