Evaluation of Rainwater Harvesting Systems for Domestic and Agricultural Use in Adamawa State

This study evaluates the performance and potential of rooftop rainwater harvesting systems for both domestic water supply and supplemental irrigation in Adamawa State, North East Nigeria. Adamawa State experiences significant seasonal water stress, with rural communities dependent on unreliable surface water sources for both drinking and farming. Rooftop rainwater harvesting offers a decentralised, low-cost water supply option that can supplement piped water supply and support small-scale home garden irrigation during dry spells within the rainy season. This study installs standardised 5,000-litre polypropylene storage tanks connected to zinc aluminium roof catchments on 20 rural homesteads in Yola South, Song, and Numan local government areas. Rainfall data from meteorological stations are used to model annual water yield potential. Water quality testing assesses first-flush contamination, bacterial load, and suitability for irrigation. Household water balance analysis evaluates the contribution of harvested rainwater to total water needs. Findings reveal that the average catchment area of 60 square metres per household yields approximately 56,000 litres per rainy season at the study locations' average annual rainfall of 950 millimetres. First-flush diverters reduce total coliform counts to acceptable levels for irrigation. The supplemental water is sufficient to irrigate a 50 square metre home garden for 60 days of dry spell within the rainy season. The study recommends rainwater harvesting as a complementary water security strategy for Adamawa State rural households.

Keywords: rainwater harvesting, domestic water supply, supplemental irrigation, Adamawa State, rural water.