Assessing Water Resource Availability and Utilization in the Mahi River Basin: A Comprehensive Analysis using Water Accounting Plus (WA+)

Water resource evaluation and management rely heavily on detailed and well-classified data on water supply, demand, consumption, and withdrawals. The Water Accounting Plus (WA+) framework provides an effective platform to anticipate water flows by integrating remote sensing data to analyze water flows within a basin while accounting for land use. For the Mahi River, we used the WA+ framework to get insights about water inflows, outflows, consumption, withdrawals, and storage changes. The WaterPix (soil moisture water balance) model was employed to simulate hydrological processes at the pixel level. Here, we also employed blue and green water estimates to classify between irrigated and rainfed regions. The present state of the basin's water resources was also computed using performance indicators. As per our study, the Mahi River basin experiences water scarcity and heavily depends on groundwater (GW) for agriculture. From 2012-2020, there has been an average annual outflow of 20.65 BCM, with average annual flows of exploitable and available water being 34.07 BCM/year and 30.38 BCM/year, respectively. Furthermore, the average vertical GW recharge and outflow were 17.47 BCM/year and 21 BCM/year, respectively. Though, the average surface water (SW) withdrawal was lower and concentrated in a few regions. The outcomes from the GW sheets demonstrated a considerable dependence on GW, with 95% of the used flow coming from GW. Notably, over the study period, there was a 25% reduction in water storage, emphasizing the challenges of excessively using GW for irrigation and the decrease in water storage within the Mahi River basin. The conclusions of our study give local and national authorities important new information that they can use to spot regions with poor water management practices and create water management strategies and programs that are suitable for the basin's requirements.