Climate change adaptation strategies for sustainable water management in the Indus basin of Pakistan

Pakistan's agriculture faces water security challenges owing to insecure water supply and bad governance. The increasing food demand of the growing population and climate change vulnerability are future key threats to water sustainability. In this study, the current and future water demands as well as management strategies are evaluated for two climate change Representative Concentration Pathways (RCP2.6 and RCP8.5) for the Punjab and Sindh provinces in the Indus basin of Pakistan. The RCPs are assessed for the regional climate model REMO2015, which was found to be the best-fitting model for the current situation in a preceding model comparison using Taylor diagrams. The status quo water consumption (CWR_area) is estimated to 184 km³ yr^-1, consisting of 76 % blue water (freshwater from surface water and groundwater), 16 % green water (precipitation), and 8 % grey water (required to leach out the salts from the root zone). The results of the future CWR_area indicates that RCP2.6 is more vulnerable than RCP8.5 in view of water consumption as the vegetation period of crops is reduced under RCP8.5. For both pathways (RCP2.6 and RCP8.5), CWR_area increases gradually in the midterm (2031-2070) and becomes extreme at the end of the long term (2061-2090). The future CWR_area increases up to +73 % under the RCP2.6 and up to +68 % in the RCP8.5 compared to the status quo. However, the increase in CWR_area could be restrained up to -3 % compared to the status quo through the adaptation of alternative cropping patterns. The results further show that the future CWR_area under climate change could be even decreased by up to -19 % through the collective implementation of improved irrigation technologies and optimized cropping patterns.