Utilization state and thought on rainwater harvesting in Kenya

Kenya is in East Africa and has a tropical monsoon climate. Prolonged droughts and unexpected shifts in normal weather patterns are the main hurdles preventing Kenya from realizing poverty eradication, food security, and environmental sustainability. Rainwater harvesting, as a highly efficient old economic technique of saving additional water, has a history spanning over thousands of years. Due to lack efficient medium for natural rainwater storage in Kenya, rainwater harvesting has become a critical mode of fighting off drought in the country. A systemic analysis of the state of rainwater harvesting was conducted along with the local climatic, hydrological and geographic conditions for realistically determining highly efficient storage and use of rainwater. In this study, based on virtual field trips and discussions with local farmers and researchers in educational institutions, the state of utilization of various rainwater harvesting systems in Kenya was evaluated. The study analyzed the differences in space and time in rainwater collection methods at courtyard, farmland and basin levels. The study also determined rainfall, infiltration, runoff and evaporation in relation to regional water cycle and water balance. The analysis showed that it was critical to increase the total volume of water resources by using various rainwater harvesting techniques, and to reduce invalid evaporation, especially unproductive water evaporation. The main way of increasing the volume of available water resources was by scientifically using natural and artificial water storage media. Even though rainwater harvesting systems that had relatively mature technologies were very common in daily domestic life, there was still big development space for improvement in less than 500 mm annual rainfall in agricultural production area. The prevailing problems faced in the region were how to improve the low efficiency of rainwater harvesting, and to reasonably store and efficiently use collected rainwater in the arid region. Given the weak regulation and storage capacity of the local soil to redistribute rainwater, it was necessary to balance water supply and demand during crop growth period. One way of doing this was by regulating short-term storage and rainwater by excavating trenches in farmlands. This implies the early harvest of extra rainwater in raining season and then irrigated crops at the later stages of growth when there was no rainfall. The suggestions and recommendations in this research will lay the reference needed to increase the role of rainwater harvesting in agricultural production in Kenya and in other arid and semi-arid regions around the globe.