The study enhances the Soil and Water Assessment Tool (SWAT) to simulate saturation-excess overland flow in neotropical high-elevation grasslands (paramos) in Ecuador, addressing issues with traditional SWAT assumptions about runoff. Given the unique soil properties in these regions, characterized by high conductivity and water retention, the model’s calibration considered various hydro-physical soil attributes to improve runoff predictions.
Results indicated that the modified SWAT effectively mirrored daily discharge during both dry and wet periods, with Nash-Sutcliffe efficiency (NSE) values reaching 0.86 during calibration. The model demonstrated a significant ability to partition total runoff into lateral flow (99.3%) versus surface runoff (0.7%), highlighting the dominance of saturation-excess flow in paramo hydrology. Limitations were noted in simulating low flow rates, a common challenge across various hydrological models applied in similar environments.
The study emphasizes the importance of considering specific soil characteristics and hydrological processes for accurate modeling in Andean paramo catchments. It advocates for future research in this area, implying potential misrepresentation of hydrological behaviors when assuming infiltration excess as primary runoff processes. Overall, the findings suggest that the enhanced SWAT model can serve as a valuable tool for understanding hydrological responses in sensitive Andean ecosystems.
