Résumé
The intensification of irrigated agriculture in Morocco, coupled with a series of droughts, is leading to unprecedented groundwater depletion. Highly incentive public policies have led to a significant increase in areas irrigated by drip irrigation in recent years. This change in technique is accompanied by the digging of small reservoirs designed to store water the pumped on the farm. This article aims to demonstrate that the number and surface area of these reservoirs are an indirect proxy of groundwater dynamic and, where appropriate, depletion. Using time series of satellite observations, we count the number of tanks and estimate their area over four overexploited aquifers (Errachidia, Haouz, Saïss, and Zagora) with contrasted dynamics representative of the evolution of agricultural practices in Morocco. The technique is applied over the period 2016–2023 to report on the annual evolution of those tanks. The validation showed a very good accounting (rRMSE of −1.2 %) and an overestimation of the area (+14 %). The striking increase of tanks in each aquifer is closely linked to the generalized water table drop. Nevertheless, it is also observed that each aquifer has its own dynamics. In the palm tree corridor of Errachidia, the number of reservoirs has increased tenfold in those seven years. In the Haouz and Saïss aquifers, it has doubled. In the Zagora region, the aquifer level is already dramatically low and the trend of irrigation tanks is towards stabilization, with as much abandonment as construction of tanks. The method could help offset limited groundwater data and support monitoring and transparency—key elements of effective groundwater governance.