This is justified by the fact that tube wells do not meet herders’ needs. This same method was then subsequently tested and validated on two other aquifers, one in Nigeria and one in Niger.ĭrilling campaigns have not explored the northern parts of the basin despite a large proportion of overall groundwater abstraction taking place in this area. We have developed a remote sensing technique that allows us to (a) identify pastoral wells, (b) isolate the tracks left by the animals used to draw water, and (c) use these animal tracks to estimate the water depth.Īfter carefully calibrating the method, we were able to use open data (Landsat) and satellites images freely accessible data thanks to Google Earth Pro (SPOT and Worldview) to draw up, in just a few weeks, the piezometric map of a large aquifer (200,000km 2) that is not easily accessible by other means due to the prevailing insecurity that has persisted in this part of the Sahel region for several years. When pulling on this rope, the animals leave deep tracks on the ground that can be observed and measured on satellite images.

To draw water, they hitch oxen or camels to a rope whose length is an accurate measure of the depth of the piezometric surface of the water table.

In the northern Sahel, pastoralists water their livestock from deep wells. Thanks to high-resolution satellite images, the tracks made by cattle, goats and camels in the Sahara and Sahel could become a key indicator of the depth of the water table. To ensure the sustainable development of these regions, it is therefore essential to develop accurate piezometric maps, even in the areas that are most difficult to access. The daily life and work of the herders are organised around the location of the wells and the depth of the water table.

In the Sahara and the Sahel, groundwater is a limited and indispensable resource for pastoral livestock farming.

Wunderground satellite