A numerical model approach to evaluate the efficiency of indigenous rainwater harvesting techniques for agriculture

The sub-Saharan climate is experiencing a marked increase in temperature and intensification of precipitation intensity and variability. Besides, longer dry spells are compromising the reliability of local agricultural practices. The present study provides a comprehensive investigation about the benefits induced using indigenous rainwater harvesting techniques (RWHT) against hydrometeorological threats affecting the Sahelian areas (SA). The RWHT have been tested in term of runoff retention, infiltration increase into the root zone and vegetation water stress mitigation. To achieve these purposes, hydrological processes at the field scale have been investigated using a two‐dimensional distributed hydrological model. To make the study representative of the whole Sahelian areas, a series of simulations were carried out using a wide range of input parameter sets generated through Latin Hypercube Sampling (LHS) representative of conventional values of those areas. The results show a runoff retention driven by the RWHT configuration up to 89% and a rise in the infiltration of 85%. Intercepting and storing overland flow, RWHT increase the water content in the root zone decreasing the time in which the crop experiences stress of 25%. The combination of these effects reduces the climate-related water stress and enhances the survival expectation of new plants.