Rapid expansion of irrigated agriculture in the Senegal River Valley following the 2008 food price crisis

The expansion of irrigated croplands throughout the 20th century boosted global agricultural productivity, yet limited improvement occurred in sub-Saharan Africa where many irrigation schemes and policies under-delivered. We mapped the distribution of croplands under active irrigation between 1986 and 2020 for one of Africa's largest and most important transboundary river basins – the Senegal River Valley (SRV); using Landsat imagery with a Random Forest classifier and Hidden Markov Model. We document two distinct epochs of irrigation development. Initially, a period of stagnation where less than 900 ha per year was added, lasting until 2008. Followed by a boom phase of rapidly expanding intensively irrigated production with ∼ 9,000 ha per year added for the last 12 years. These epochs overlap with national agricultural policy frameworks: the 1980s laissez-faire policies limited state involvement in agriculture and promoted Asian imports; followed by a more interventionist period focused on promoting domestic production following the food price crisis of 2008.