High resolution water scarcity analysis for cotton cultivation areas in Punjab, Pakistan

Abstract

The Water Scarcity Footprint (WSF) serves as a method to estimate the local impacts associated with water consumption in a certain region by considering the volume of water consumed and local water scarcity. Despite the broad application of the WSF on a country and river basin level, the need for further regionalization was recently emphasized by several authors. In this study, water scarcity factors are calculated on high spatio-temporal resolution for 17 irrigation subdivisions located in Punjab, Pakistan on a monthly level based on the WAVE + method using data provided by the hydrological model SWAT and hydraulic model Feflow. The calculated “water deprivation indices” (WDIs) are applied to quantify the WSF of cotton and wheat produced in the study area and compared to the WSFs obtained by using existing WDIs with lower spatial and temporal resolution. The calculated WDIs show a high variability in water scarcity throughout the year from 0.1 to 1.0 m3deprived/m3consumed. The production weighted average WSF of cotton calculated with the regionalized WDIs amounts to 2333 m3deprived per ton, whilst the cotton produced in the south of the study area has a twice as high WSF as the cotton from the northern irrigation subdivisions. The result calculated based on the high resolution WDIs is more than 60% higher than the WSF calculated with the WDIs on the basin level. The regionalized WSF of wheat amounts to 1821 m3deprived per ton, which aligns with the WSF calculated with the basin specific WDIs. The study underlines the need for water scarcity factors on high spatial (e.g. irrigation subdivision) and temporal (monthly) resolution to provide robust WSF results.