Impacts of Irrigation Development on Regional Rainfall in Africa

Abstract:

Potential modification of regional rainfall by large-scale cropland irrigation has been investigated in several regions of the world. In particular, regional climate simulations over West Africa indicate that hypothetical large-scale irrigation schemes reduce rainfall over the irrigated areas but enhance rainfall remotely. However, these theoretical results cannot be substantiated without direct comparison to observations. We therefore conducted two complementary analyses over an actual, large-scale irrigation scheme in Africa: numerical simulations using a regional climate model, and observational analyses using several surface-based and satellite-derived datasets. For the observational analyses, we analyzed spatial and temporal patterns of both rainfall and air temperature in and around the irrigated area. For the numerical simulations, we examined multiple variables that contribute to an improved understanding of the mechanistic pathway between irrigation and rainfall modification. The results of both the simulations and observational analysis will be presented.