Hydrological modeling and scenario analysis for water supply and water demand assessment of Addis Ababa city, Ethiopia

Abstract

Study region: Addis Ababa, capital city of Ethiopia. Addis Ababa’s surface water reservoirs and groundwater infrastructures are in the Akaki watershed of the Awash Basin. Study focus: This study integrates a hydrological model, socioeconomic data, and different water management scenarios to investigate the current and future water supply and demand. Baseline water supply and water demand data are obtained from Addis Ababa Water and Sewerage Authority. The Soil and Water Assessment Tool (SWAT) model was used to simulate reservoir sedimentation and water quantity in the Akaki watershed. The city’s water demand projection is based on the standard public water demand requirement and projected population. The study considered five scenarios to assess the gaps between water supply and demand. New hydrological insights for the region: Simulation results showed that the area upstream of the existing reservoirs has the potential to supply 651,452 m3/day of surface water; however, currently, the reservoirs are supplying only 224,658 m3/day of water. With an optimistic scenario of planned reservoirs and groundwater boreholes becoming operational by 2029, water supply will only meet demands through 2035. Afterwards, the gap between water supply and demand will increase, due to an increase in population. Therefore, additional water supply projects, effective water use, and maintaining critical hydrological ecosystem services are required to bridge the gap between water supply and demand.

Keywords

• Hydrological modeling
• Water supply and demand
• Reservoirs
• Sedimentation, Water management scenarios, Addis Ababa