Assessment of Crop Water Requirement in the Context of Climate Change

Abstract

Climate change is influencing and will continue to affect essential natural resources, such as water. Its effect on agriculture is usually considered as one of the most serious challenges in water resource management. In this study, the bias-corrected future climate data from the global climate model (GCM), ACCESS-ESM1.5, has been used to estimate the monthly crop water requirement for paddy in the Seonath sub-basin, Chhattisgarh State, India. The bias-corrected outputs of the ACCESS-ESM1.5 GCM model and projection of the future temperature and rainfall were done for two Shared Socioeconomic Pathway (SSP) scenarios, namely the SSP370 and SSP 585. Further, the future crop water requirement was calculated for the SSP370 and SSP585 scenarios using the CROPWAT model for the period of 2015–2099 with three future periods (FP) 2015–2045, 2046–2075, and 2076–2099. The reference evapotranspiration ETo was calculated using ETo calculator given by FAO. The results indicate rising in temperature and rainfall over future periods when compared to the base period (1981–2014). The annual average temperature has been projected to increase by 2.07 °C and 2.61 °C from 2015 to 2099, when compared to the base period for the SSP 370 and SSP 585 scenarios, respectively. The annual average rainfall has been projected to increase from 1207.7 mm in the base period to 1441.1 mm and 1400.1 mm for SSP 370 and SSP 585 scenarios. The average reference evapotranspiration (ETo) values showed an increase from 4.54 mm/day to 4.61 mm/day and 4.72 mm/day for SSP 370 and SSP 585 scenarios, respectively. The average annual crop water requirements (CWRs) showed an increase of 17.01% and 18.45% for the SSP 370 and SSP 585 scenarios. For optimal irrigation planning, projected deviation in required values can be used in the culturable command area of the Seonath sub-basin.