Rainwater harvesting potential for crop production in the Bugesera district of Rwanda

The objective of this study was to test the utility of a spatial explicit water balance technique in assessing the rainwater harvesting potential for crop production to design food security strategies in the Bugesera District. The district was delineated into 19 catchments through the hydroprocessing algorithm in ILWIS using the SRTM 90 m DEM, and runoff, a proxy of the potential rainwater harvest, was computed using the Natural Resources Conservation Service Curve Number method. Results from the analyses indicate that based on the average antecedent moisture condition, the average daily runoff that can be collected out of Bugesera district is approximately 1,320 x 106 m3/day. Allowing a third of this runoff for environmental requirements and evaporation losses, the amount of rainwater that could be used for crop production has been estimated to be 880 x 106 m3 per day. By using the CSIRO’s precision weighing systems to measure water use by various crops and yield from the crops, the amount of harvested rainwater has the potential of producing between 398 x 103 to 531 x 103 tones of paddy rice and 1,390 x 103 to 1,620 x 103 tones of maize. This potential crop yield can significantly improve food security in the Bugesera district. It was therefore concluded that rainwater harvesting for crop production is a viable option in Bugesera district and further implantation modalities should be explored.   Key words: Rainwater harvesting, natural resources conservation service (NRCS) curve number, crop production, digital elevation model (DEM), catchment delineation, Bugesera District.