La sécheresse dans la France de l'Ouest : une contrainte climatique trop souvent oubliée
Résumé
Water balance for all the stations of the western part of France shows an obvious risk of drought occuring mostly in summer. If this problem does not seem to be important with means, the interannual variability of evaporation deficiency (difference between Turc Potential Evapotranspiration and Actual Evapotranspiration) underlines the phenomenon with a best accuracy: this rather qualifies the common image of these "continuously wet" oceanic regions. Moreover, there is a great spatial diversity, from high and rainy hills to the southern and oriental dry basins (Anjou, Rennes). The main rural activities (ma‹ze and pasture lands) were hardly affected by the recent drought years of 1989 and 1990. This could be an increasing problem for these regions if, as shown by most of global change scenarii and the study of august's precipitations, the amplification of summer deficiency was confirmed in the future.