A framework for estimating agricultural water requirements: Accounting for anthropogenic activities and climate change

Abstract

The present research introduces a framework titled the Decision Support System for Water Resources and Agriculture under Anthropogenic Activities and Climate Change Impacts (hereafter, AnthroClimDSS). This framework incorporates several methods: I) a two-step calibration of the Soil and Water Assessment Tool (SWAT) using streamflow data and Actual Evapotranspiration (ETa) estimation from the Surface Energy Balance Algorithm for Land (SEBAL); II) evaluation of fifty high-resolution daily downscaled CMIP6 global climate models (GCMs); and III) introduction of indicators to assess water supply risk, including the Agricultural Water Requirement Supply Index (AWRSI). A historical analysis of AWRSI in a sub-basin of Urmia Lake, Iran, reveals that, although agricultural water demand was fully supplied, significant pressure was placed on water resources, particularly groundwater, due to anthropogenic activities. Projections using GCMs within the AnthroClimDSS framework show that future climate change impacts are likely to be substantial. Continuing current practices could lead to severe water scarcity (possibly bankruptcy) and environmental degradation, as water demands increasingly outpace sustainable supply. However, scenario analysis suggests that the adverse impacts of both climate change and human activities can be mitigated through targeted agricultural water management at the farm scale. The proposed AnthroClimDSS framework offers a valuable tool for watershed planners to develop and implement more sustainable water resources management strategies.