There is no doubt about the over exploitation of the Berrechid aquifer which spreads on an area of 1500 km2, as the piezometric surveys show. This aquifer provides a large part of the drinking water supply and all of that used in irrigation. In deed there is a high demand of agricultural product from the Casablanca city located fifty kilometers away.
Mathematical models have been developed and scenarios proposed. However, the conceptual model suffers from some inaccuracies especially in its component relating to the recharge.
The most part of this aquifer is unconfined whereas a small part of it is confined under thick deposits of clays. The matrix of the aquifer is of Plio-quaternary age and is declined in the form of filling deposit with lateral changes of materials thus inducing a great variability of permeability. The substratum consists of formations of different ages with a topography that shows a network of paleo-channels that seems to have been the continuity of the current network located to the south. They are separated from the plain by a fault that morphologically draws a cliff. Structurally, this basin is organized as blocks shaped by perpendicular fault families existing in this geological unit.
The compilation of two isotopic studies, in which measurements of deuterium and oxygen 18 has been carried out, made it possible to draw a number of conclusions (i) a dominance of the phenomenon of evaporation of infiltrated waters which is a characteristic of the semi-arid climate and which is accentuated by the endoreism of the Berrechid plain, (ii) the recharge is also done upstream by the runoff drained by a number of small watersheds which flow into the plain during the winter season, (iii) demonstration of a control of hydrogeological conditions on groundwater flows.
The use of the isotopic tool has brought an additional degree of precision to the conceptual model and consequently to the result of the mathematical one.