Review on Crop Water Requirements in Ethiopia

Agriculture in Ethiopia, which is predominantly dependent on smallholder rain-fed production systems, remains highly vulnerable to climatic variability, recurrent droughts, and increasing water scarcity. Accurate estimation of crop water requirement (CWR)- the volume of water required to satisfy crop evapotranspiration (ETo) for optimal growth is fundamental for irrigation design, crop planning, and sustainable manage net of limited water resources. In the Ethiopian context crop water requirement (CWR) coupled with crop coefficient (Kc) approaches, operationalized through decision support models such as CROPWAT and Aqua-Crop. However, substantial spatial and temporal heterogeneity in climatic variables, soil properties, and cropping systems creates high uncertainty in current estimations. Additionally, inadequate meteorological coverage, insufficient temporal data resolution, and the scarcity of locally calibrated Kc values constrain the accuracy and applicability of results across diverse agro-ecological zones. Recent climate projections under moderate emission pathways (e.g., RCP4.5) indicate a significant rise in temperature and altered rainfall distribution, potentially intensifying evapotranspiration and shifting seasonal irrigation demand. Emerging studies utilizing satellite-based evapotranspiration retrievals, downscaled climate models, and GIS-integrated hydrological simulations have improved crop water requirement (CWR) mapping and spatial analysis. Nevertheless, the integration of green-water (rain-fed) and blue water (irrigation) components into comprehensive water balance frameworks remains underdeveloped, limiting the translation of findings into actionable adaptation strategies. Bringing the methodological and data gaps through advanced spatial analysis tools, remote sensing technologies, and climate smart irrigation modeling is imperative for strengthening Ethiopia’s food and water security and ensuring resilient agricultural development under climatic conditions.