A WEAP-based Modeling Approach to Project the Irrigation Demand under IPCC Climate Change Scenarios in the Rechna Doab

Abstract

Pakistan is currently facing physical and economic water scarcity issues that are further complicated by the rapid increase in climate change. The main source of water in Pakistan is the Indus River system, issues that impede the implementation of Integrated Water Resources Management (IWRM) strategies include the transboundary nature of the Indus River, limited availability of data, and inadequate management of water. These problems result in a gap between water demands and supply in various water-consuming sectors. In Pakistan, agriculture is the major consumer of water and utilizes more than 95% of the country’s water resources (Bhatti et al., 2014).The agriculture sector’s contribution to the GDP of Pakistan is almost 25% and provides jobs for 42 % of people (Hassan et al., 2019).The agriculture of Pakistan is based on irrigation where rainfall marginally meets 15% of crop water requirements. Irrigated agriculture is associated with the Indus Basin, which provides irrigation water on a supply basis. Groundwater covers 40–60% of the irrigation needs to meet the deficit in surface water supplies (Muzammil et al., 2020). The research was conducted at the Rechna Doab, Indus Basin Irrigation System (IBIS) of Pakistan, using the WEAP (Water Evaluation and Planning) model. The purpose of this study is to assess the supply-demand gap of canal water that helps to achieve water security and sustainability in the Indus basin irrigation system by considering climate change scenarios presented by IPCC in its Assessment report six (AR6) published recently in 2021 using the WEAP model. Results reveal that in both Climate Change Scenarios SSPS 45 & SSPS 8) the unmet demand will increase and demand site coverage will decrease. Future annual water demand of Upper Chenab Canal, Upper Gugera, Lower Gugera & Jhang branch CCA will increase by about 33%, 47.1%, 45% & 40.3% under SSPS 85 at the mid of the century. Estimation of the future water supply demand conditions indicated that the water demand coverage will drop from 25% to 16% in the Lower Gugera branch, 29.2% to 19.7% in the Jhang branch, 64% to 45 % in the Upper Gugera branch and 78% to 64% in Upper Chenab canal.