International Journal of Environment and Climate Change

Water is a crucial and finite resource, primarily utilized for irrigation, necessitating effective distribution for long-term sustainability. This study quantifies the water requirements for summer paddy cultivation in Raipur district, Chhattisgarh, and assesses its implications under changing climatic conditions. The FAO-CROPWAT 8.0 model was applied to assess irrigation parameters using historical meteorological data from 2000 to 2020 and projected meteorological data from 2040 to 2100. Reference evapotranspiration (ET₀) was estimated using Penman-Monteith method, incorporating crop coefficient (K_c) values to determine crop evapotranspiration (ET_c). Irrigation water requirements were estimated by accounting for various losses and efficiencies of crop and field. Comprehensive water balance models were developed across the century, focusing on a 20-year average time span, including the historical period as 2000-2020 and the predicted time span from 2040 to 2100 with two socio-economic scenarios: SSP2-4.5 and SSP5-8.5, along with soil, meteorological, and phenological factors. Over the baseline period, the crop water requirement (CWR) for summer paddy was calculated as 751.4 mm, with net irrigation water requirement (NIWR) and gross irrigation water requirement (GIWR) as 1094.7 mm and 1563.8 mm, respectively. Under SSP2-4.5 scenario, the minimum and maximum temperatures are projected to rise by 1.3 °C and 1 °C respectively with rainfall increasing by 378.5 mm. This scenario anticipates a CWR increase of 32.6 mm by century's end, resulting in final values of CWR as 784 mm, NIWR as 1164.7 mm, and GIWR as 1663.9 mm. In the SSP5-8.5 scenario, temperatures are expected to rise by 4.4 °C and 3.1 °C as minimum and maximum temperature, leading to a CWR of 800.4 mm, with NIWR and GIWR as 1176.5 mm and 1680.7 mm, respectively. Overall, most parameters indicate an upward trend throughout the century. This study provides critical insights for efficient irrigation management in summer paddy cultivation and highlights the implications of future climate change on irrigation needs, promoting sustainable agricultural practices.