Abstract:
Crop production in semi-arid Sub-Saharan Africa (SSA) is limited by over-reliance on rainfall, which is erratic and
inadequate. Rainwater conservation and irrigation are needed to avert drought effects and dry spells, and extend crop production
activities to dry seasons. A study was conducted from 2011 to 2013 at Ukwe area in Malawi, to determine the size of seasonal open
surface reservoir and crop field in relation to catchment characteristics among smallholder farming communities, using beans as a case
study crop. There is positive linear relationship between seasonal harvested watershed runoff and rainfall (over 75%). Based on the
catchment characteristics and crop water requirement, catchment/cultivated area ratio was 2.1. Harvested runoff water is linearly
related to seasonal rainfall amount. About 6000 m3 of water was required to irrigate a hectare of beans. Total volume harvested was
estimated to support six-fold the current field area at bean water productivity of 0.7 g L-1. It is possible to determine dry season bean
water productivity based on integrated effects of catchment characteristics, runoff water reservoir capacities and irrigation water
requirement.
