Mapping agricultural water dynamics and management pathways in Kenya’s Central Highlands

Owusu, Afua; Velpuri, Naga Manohar; Magesa, R.; Adamseged, Muluken Elias; Schmitter, Petra S.

Mapping agricultural water dynamics and management pathways in Kenya’s Central Highlands

Autores

Owusu, Afua

Velpuri, Naga Manohar

Magesa, R.

Adamseged, Muluken Elias

Schmitter, Petra S.

Editor

International Water Management Institute
CGIAR Sustainable Farming Program

Descripción

Agricultural water management in Kenya’s Central Highlands is increasingly challenged by population growth, land-use change, and climate variability, intensifying competition for limited water resources in a region critical to national food security and biodiversity. This study maps agricultural water dynamics and management pathways across the Central Highlands Ecoregion Foodscape (CHEF), combining basin-scale water accounting with crop-level water demand analysis to identify key constraints and opportunities for water-secure agriculture. Using the Scale Invariant Water Accounting Plus (SIWA+) framework and the Securing Water Use in Agriculture (SWAG) tool, the analysis integrates bias-corrected climate and discharge data with high-resolution (30 m) evapotranspiration estimates over a five-year period (2019–2023). The results reveal that CHEF is an almost fully allocated basin, with limited scope for additional surface water withdrawals. While over-irrigation is localized and largely confined to perennial systems, widespread crop water deficits persist across rainfed and marginal agricultural zones, particularly during critical growing periods. This indicates that the primary challenge is not increasing water supply, but improving the timing, efficiency, and allocation of existing resources. To address this, the study evaluates the potential of small-scale on-farm water storage as a buffering strategy. Simulations show that distributed ponds of approximately 1,000 m³ can significantly enhance intra-seasonal water reliability by capturing excess runoff during wet months and supplying strategic supplemental irrigation during dry spells, without substantially reducing annual downstream flows. However, the findings also highlight risks associated with cumulative storage expansion, behavioural responses, and sedimentation, underscoring the need for basin-scale governance and monitoring. Overall, the study provides an updated, spatially explicit evidence base to guide investments, agronomic interventions, and policy decisions aimed at strengthening water sustainability and food system resilience in Kenya’s Central Highlands.