Integrated modeling of the generation, attenuation, and transport of point-source pollutants at the watershed-scale using SWAT+

Abstract

Addressing the chemical pollution of surface water bodies requires a good understanding of pollutant and system dynamics. Numerical modeling represents a valuable tool to support sustainable water management, especially due to its capacity to explore climate and management scenarios. We introduce a novel integrated modeling framework to capture the dynamics of point-source pollutants at the watershed-scale. It comprises a pollution generation model, an attenuation and transport model built within SWAT+, and a custom Python library (pySWATPlus) to facilitate model integration and calibration. We tested the framework for ciprofloxacin and venlafaxine in three densely populated Mediterranean basins, and we successfully calibrated it using observed concentrations in the river network. This research advances water quality modeling by integrating point-source pollutant dynamics from source to in-stream fate with the widely used model SWAT+. It also offers a valuable tool for evaluating mitigation strategies, supporting compliance with regulations, and informing sustainable water management.