Predicting the water use-demand as a climate change adaptation strategy for rice planting crops in the Long Xuyen Quadrangle Delta

This work evaluates the impacts of climate change on water use-demand of three rice planting crops including winter–spring (WS), summer–autumn (SA) and autumn–winter crops for Long Xuyen Quadrangle Delta of Vietnam. Climatic variables scenarios were obtained from the updated report on emission scenarios which are issued by Vietnam’s Ministry of Natural Resources and Environment for three future timescales (2016–2035, 2046–2065 and 2080–2099) of representative concentration pathways (RCP) 4.5 and RCP8.5 scenarios. Cropwat model was selected to evaluate the irrigation water demand of three rice planting crops based on simulating actual evapotranspiration (ETc) and effective rainfall for the study area. The results showed that the WS and SA planting crops need more irrigation water demand in the growing and developmental stage for timescales of RCP4.5 and RCP8.5 scenarios. Results also pointed out that compared with current climate condition the tendency to decrease in irrigation water demand in the initial and developmental stages of autumn–winter planting crop with arranging from 2.9–12.9 to 10.0–18.2%, respectively, corresponding to timescales of RCP4.5 and RCP8.5 scenarios is found and a significant downward trend in the late stage approximately 5.8–20.0% and 13.6–20.7%, respectively, for RCP4.5 and RCP8.5 scenarios also recorded.