Assessing the potential of harvesting rainfall runoff using pans to meet Marigat's water demand: an application of WEAP21 model

Water resources are vital to basic livelihoods and economic growth. Marigat division in Baringo County, Kenya experiences water scarcity during the dry periods, a situation that is further aggravated by droughts and erratic rains. During the rainy seasons, a lot of water is lost as surface runoff, which can be harvested and stored in water reservoirs and used for domestic and livestock throughout the dry seasons. Water Evaluation and Planning (WEAP21) system model was used to determine whether the water to be harvested from rainfall runoff was able to meet the Marigat community's water demand. This was achieved by building creation of proposed new water pans scenario from the reference scenario. The results of the reference scenario were validated using observed river flows at Marigat Bridge station, and WEAP21 was also used to develop a water supply network. The results show that with the creation of proposed new water pans for harvesting surface runoff in areas facing water scarcity, the unmet domestic and livestock water demand is met up to 2020.