Méthodes d’estimation et d’extrapolation des pompages des eaux souterraines par l’intégration des pratiques locales: cas de la plaine du Saïss au Maroc

Abstract

In the Saïss plain, the access to groundwater enabled the rapid transformation of farming systems (extension of arboriculture and horticulture) and the production of wealth. However, these changes affect only a minority of farmers who are able to access and use groundwater. This rapid agricultural development has contributed to the creation of social and economic inequalities, but also to a decline of groundwater tables. The actual groundwater abstractions for agriculture are not monitored and it is difficult to determine the share of different types of farming systems and farmers responsible for the groundwater withdrawals and identify the levers to control groundwater overexploitation. The aim of the paper is to develop and compare four methods to estimate and extrapolate agricultural groundwater withdrawals, distinguishing between uses and users. Our observations show that in the study area (4200 ha in Saïss, located in the province of El Hajeb), the groundwater inequalities are primarily a function of unequal access to land, because 0.5% of the farmers (who are large investors) contribute to 27% of the groundwater use, on 33% of the total surface area. Conversely, the beneficiaries of the agrarian reform (26% of the area) account for only 14% of the overexploitation. But the land inequality is not always the cause of inequality of groundwater use, since lessees, practicing intensive horticulture, are responsible for 33% of the groundwater use on only 11% of the surface area. We evaluated the appropriateness of different methods of extrapolation of agricultural groundwater use, based on the objectives and the effort required to obtain the necessary data. It is important to make visible inequalities in groundwater use, to analyze the overexploitation issue and enhance the effectiveness of the control of the groundwater use.