Impact of Climate Change on Regional Water Availability and Demand for Agricultural Production: Application of Water Footprint Concept

The sustenance of rice cultivation in a region is highly dependent on future water availability under changing climate. The dams and reservoirs can play a major role in regional water availability since their storage capacity can cushion the water stress due to changes in rainfall and temperature patterns. The current study developed a simulation modelling framework to quantify the water availability and demand on a taluk scale in the command area of the Malampuzha Irrigation Project (MIP). The Blue and Green water footprint concept is used to analyse the water availability and demand in the region. The loosely coupled framework of SWAT, DSSAT, and a Reservoir Simulation Module helps to generate the hydrological and crop yield projections of the region according to the CMIP6 climate model projections. The analysis is carried out at a seasonal scale on decadal basis with a historical period spanning from 2016 to 2019 and a future period spanning from 2020 to 2100. The results suggest that eastern side of MIP command area experiences lower water availability due to lower green and blue water distribution, particularly affecting the regions of Palakkad and Chittur taluk. The study introduces an integrated water footprint score (IWFS) at taluk scale, which combines green and blue water footprint to assess the annual water demand variations in the region. The taluks Alathur and Palakkad are in the high risk category towards the end of the century as per the water footprint score. Towards the end of the century, an increase in rainfall by 67% and temperature by 6% has resulted in a decrease in rice yield by 13.2% during kharif and 52.5% during rabi season under SSP585 scenario. The study helps to identify critical water stress zones within the command area and prioritize the implementation of adaptation measures within the command area.