Dennis Gikonyo Mwangi^1,2 , Basil Iro Tito Ongor¹ , Edwin kimutai Kanda¹

1 Department of Civil and Structural Engineering, Masinde Muliro University of Science and Technology P.O Box 190-50100 Kakamega, Kenya
2 Lake Victoria Water Works Development Agency, P.O Box 673-50100, Kakamega, Kenya
Author    Correspondence author
International Journal of Aquaculture, 2026, Vol. 16, No. 2   
Received: 05 Dec., 2025    Accepted: 26 Feb., 2026    Published: 14 Apr., 2026

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Effective water allocation in river catchments experiencing rapid population growth, land-use change, and climatic variability remains a pressing global concern. This study evaluated the future scenarios of water demand within the Middle Nzoia Catchment in western Kenya using WEAP model. The study utilized a comprehensive dataset covering hydrological, water Quantity, and socio-economic variables from 1982 to 2022. Model calibration (2001-2010) and validation (2011-2020) were undertaken using observed streamflow data. Future demand scenarios to 2052, projected a potential increase to 45% from the base year under the High Growth scenario, reaching 260 million m³ annually. The agricultural and domestic sectors experienced the most significant increases, driven by population growth and intensified irrigation practices. Water allocation simulations demonstrated that during low-flow months, supply could meet only 69% - 72% of total demand, signaling potential water scarcity and inequitable distribution. Allocable water volumes were estimated at 240 million m³ annual but without integrated management strategies, unmet demand could increase to 31% to 2052. The study highlights the critical need for adaptive management approaches, including enhanced demand- side efficiency, investment in storage infrastructure, and strengthened institutional coordination. These results provide actionable guidance for policymakers, and water managers in similar hydrological contexts facing complex socio-environmental pressures.

Catchment; Water demand; Scenarios; WEAP model