Abstract
Rainfall variability and the recurrent droughts in the semi-arid regions of Sub-Saharan Africa have far reaching consequences. They have major effects on the socio-economic and environmental sustainability of rural communities. This study investigates the technical, economic, and financial feasibility of small-scale rain water harvesting, and supplemental irrigation (RWHSI) system to mitigate the negative impact of long droughts on crop production. The proposed system consists of limited farm grading to direct the harvested rain water to a lined earth-pond where several alternatives for pumping are proposed for supplemental irrigation schemes. The proposed scheme is mainly activated during the short period when the soil moisture is most critical for the crop yield. To reach an optimum size of the pond, the soil moisture during the critical growth period is simulated using FAO’s water productivity model (AquaCrop). The pond size is optimized by applying AquaCrop for several years with the actual rainfall pattern and the possible supplemental irrigation applications. For each year with its possible drought periods, crop yield for each pond size is predicted, then used for the economic feasibility of the pond sizes. The optimum pond size is the one maximizing its benefit over its cost. The feasibility of the proposed RWHSI is investigated on maize production for the Soroti area in Uganda. For the rainfall pattern, soil conditions, and maize growth characteristics of Soroti, the proposed RWHSI is proved by simulations to be technically, and economically feasible. For a typical farm holding with a catchment area of one hectare, an 800 cubic-meters lined earth-pond can give up to 50% increase in the maize yield. After considering the construction and running costs of the supplemental irrigation system, the pay-back period is 6 years. The required investment cost for this RWHSI is low, and likely to be within the financial capacity of many farmers, while their selection of the pumping system will depend on their manpower and financial ability.
Highlights
Agricultural production accounts to almost 70% of the global fresh water extractions [1]
This study investigates the technical, economic, and financial feasibility of small-scale rain water harvesting, and supplemental irrigation (RWHSI) system to mitigate the negative impact of long droughts on crop production
This study proposes that a farmer can sacrifice 5% of his cropland to construct a micro storage system that can collect surface runoff and use it primarily during the critical growth stages for a maize crop
Summary
Agricultural production accounts to almost 70% of the global fresh water extractions [1]. Different researchers have suggested that supplemental irrigation to rain-fed agricultural settings could be a potential solution to the increasing food demands [1] [2]. Rain-fed production produces up to 70% of the global food supply. The Food and Agriculture Organization (FAO) reported that almost three quarters of the fresh water resources in Sub-Saharan Africa (SSA) are used for agricultural purposes [9]. Estimates show that uncertain weather conditions as well as insufficient water for irrigation could cause the agricultural productivity in several countries to fall by up to 50% over the decade, severely affecting their prospects of greater social and economic development [10]. Almost 94% of agricultural land south of the Sahara Desert depends on rainfall for crop production [5] [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
