Assessing the Effect of Land/Use Land Cover and Climate Change on Water Yield and Groundwater Recharge in East African Rift Valley using Integrated Model

Abstract

Study region: East African Rift Valley basin. Study focus: Water availability in the rift valley relies heavily on the discharge from the highlands to rivers that run to the rift floor. This research explores the effect of Land use/Land cover (LULC) and climate change on water yield and groundwater recharge (WYGR) using coupled SWAT-MODFLOW, which integrates Soil and Water Assessment Tool (SWAT) and Newton Modular Finite Difference Groundwater Flow (MODFLOW-NWT). The LULC change was analyzed using artificial neural network-based cellular automata. New hydrological insights: The dominant LULC is cultivated land and expanded by 5% to the forest and grassland areas. The average temperature and precipitation are expected to rise by 8–11% and 3–6%, respectively. Climate change affects the spatiotemporal distribution of WYGR significantly, while LULC change has a trivial effect. Under the baseline scenario, the recharge was 10% of the average annual precipitation, but climate change is projected to reduce it by 47–53%. Water yield reduction up to 48% and change of perennial rivers to intermittent are expected in the coming decades. The region will experience water scarcity, emerging mainly from climate change.

Keywords

• Climate change
• Land use/Land cover change
• Rift Valley
• SWAT-MODFLOW
• Water yield
• Groundwater recharge