Assessing the future water demand dynamics in Manafwa subcatchment using weap

Abstract

Water scarcity poses a critical challenge in many regions, including Uganda, due to climate change, population growth, and poor water management practices. This study presents an integrated assessment of the current and future water demand dynamics in the Manafwa Sub catchment, located in Eastern Uganda. Utilizing the WEAP model, the research evaluates sectoral water demands that is domestic, industrial, livestock, and irrigation under multiple development and management scenarios from 2020 to 2050. The model was calibrated and validated using streamflow data with strong statistical performance (NSE = 0.98, R² = 0.98, PBIAS < 1.83%). Scenario simulations revealed that without intervention, water demand will rise from 40.15 MCM in 2020 to over 82MCM by 2050, with unmet demand increasing significantly under high population growth and irrigated land expansion. Management strategies such as improved irrigation efficiency, reduction in per capita domestic consumption, and rainwater harvesting were shown to substantially reduce unmet water demand with rain water harvesting showing no any unmet demand throughout the simulation period. The study highlights the critical need for proactive, integrated water resources management and provides actionable insights for achieving sustainable water allocation in the face of population pressure and climate change. The findings are instrumental in informing future water policies and supporting SDG 6 targets in Uganda.