A Novel Approach to Modeling Two-Way Feedbacks in Water Resource Management Under Climate Change

Climate change presents a pressing challenge to global water availability resulting in increased variability in precipitation and increased temperatures, imposing more stress on existing water resources (IPCC, 2023). This variability poses a significant risk to economic, industrial, social stability and also impacts agricultural sectors reliant on water availability. This study introduces an innovative modeling approach by dynamically coupling the Soil and Water Assessment Tool (SWAT) with the Positive Multi-Attribute Utility Programming (PMAUP) microeconomic model, providing a robust framework for examining the complex two-way feedback loops between hydrological changes and agricultural economic decisions. Applied to the Tormes catchment in Spain, this method demonstrates how integrated modeling can illuminate the interactions within Human-Water Systems (HWS) under various climate scenarios.

The methodology employs a dynamic interaction that begins with the PMAUP model, which acts as a responsive mechanism to climatic perturbations affecting water availability. In response to these changes and influenced by policy measures aimed at mitigating their impacts, socio-economic agents adapt their agricultural practices accordingly. The crop portfolio, reflective of these adaptive practices, is central to this methodological integration, serving as a crucial input for both the SWAT and PMAUP models.

The PMAUP model was calibrated using observed socio-economic data while the SWAT model was calibrated against observed streamflow data to capture hydrological dynamics accurately. Following calibration, CMIP6 climate scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) were input into SWAT to estimate key hydrological variables, especially water availability at the beginning of the irrigation season. This estimated water availability was then utilized by the PMAUP model to simulate agent’s adaptive responses. These updated land and water use decisions were subsequently fed back into the SWAT model to evaluate the hydrological impacts of these human decisions.

By simulating the immediate and cumulative impacts of agricultural decisions on water resources over time, this approach provides critical insights into the sustainability of water usage and the resilience of agricultural practices in response to climate variability. The dynamic coupling of SWAT and PMUAP models not only enhances the accuracy of predictions but also aids in developing adaptive strategies that are essential for maintaining balance in HWS. The actionable insights from this study serve as a vital resource for policymakers and stakeholders, offering a methodological blueprint that can be adapted to diverse geographical settings to address the global challenge of climate change.