Impact of Climate Change on Crop Water Requirements in Anantapuramu District of India using CROPWAT 8.0

Abstract

The FAO CROPWAT 8.0 model, developed by the Food and Agriculture Organization (FAO), is widely used for estimating reference evapotranspiration (ETo), effective rainfall and stage‑wise crop water requirements based on climatic, soil and crop data. Anantapuramu District, located in the semi-arid Rayalaseema region of Andhra Pradesh, India, faces severe water scarcity due to high temperatures, low and erratic rainfall and frequent droughts. Agriculture, being the primary livelihood, is heavily dependent on irrigation, making precise estimation of crop water requirements (CWR) essential for sustainable water management. This study utilized the FAO CROPWAT 8.0 model to estimate historical and future crop water requirements for major crops including cotton, maize, groundnut (rabi and kharif) and vegetables. Historical climatic data (2014–2023) and projected weather datasets generated using MarkSim DSSAT with HADGEM2-ES and MIROC-ESM-CHEM models under RCP scenarios 2.6, 4.5, 6.0 and 8.5 for 2035, 2045 and 2055 were analyzed. Results indicated that cotton exhibits the highest water demand, followed by maize, groundnut rabi, vegetable crops and groundnut kharif. Temperature, relative humidity and wind speed significantly influenced CWR, with rising temperatures and reduced humidity increasing water demand. Under future climate scenarios, CWR is projected to increase gradually across all crops, with higher emissions scenarios (RCP 8.5) showing the largest increases. These findings highlight the need for adaptive irrigation strategies, efficient water management and the adoption of climate-resilient agricultural practices to sustain crop productivity in Anantapuramu under changing climatic conditions.