Spatiotemporal impacts of climate change on evapotranspiration and crop water stress in rice and maize production in the Volta Basin

Abstract

Globally, climate change is increasing stress on freshwater resources and rainfed agriculture, disrupting food systems and livelihoods, especially in regions where there is low adaptive capacity like West Africa. The Volta River Basin (VRB) is the focus of this study because it is a lifeline to over 24 million people. This study investigates how increasing temperatures, altered rainfall patterns and increased atmospheric water demand are affecting evapotranspiration (ET) and crop water stress in maize and rice production. Using over two decades of satellite data (2000–24) and future projections under RCP 4.5 and RCP 8.5, the results indicate a pronounced but non‐linear increase in reference evapotranspiration (ET₀), with peak values occurring around 2018, followed by a decline towards 2024. This trend coincides with a warming rate of +0.012 to +0.021°C yr ‐1 and dry‐season Crop Water Stress Index (CWSI) values exceeding 0.75, extending well into the severe stress regime. Spatial analysis identifies northern and transitional areas as endemic hotspots of water stress. By integrating climate data and crop physiology, the study offers prescriptive insight for building agricultural resilience. It prescribes site‐specific interventions like drought‐tolerant crop varieties, supplementary irrigation and soil water conservation. The study informs climate adaptation, risk zoning and policy planning, ensuring food security and rural livelihoods.