Abstract

To support the hydrological assessment of Alpine ecosystems, we studied the suitability of the SWAT model to simulate neotropical alpine grasslands or so-called Andean Paramo. Given the paucity of observational data in paramo catchments, data-driven models are usually underutilized, and their outcomes are arguable. However, our research examined if SWAT can reasonably represent the hydrological response of grassland-dominated paramo catchments under data-abundance conditions. Therefore, we set up a soil-based SWAT model that emphasized the role of the soil in the hydrological response and the dominance of saturation excess surface runoff over infiltration excess. Specifically, we incorporated detailed characteristics of Andean soils by horizons, parameterized SWAT to replicate high infiltration rates and high lateral flow in the hillslopes, and restricted groundwater interactions to replicate local streamflow responses. Our soil-based modeling approach reasonably reproduced daily discharge during dry and wet periods throughout the year and the cumulative occurrence of high and low flows. The ratio of precipitation and simulated runoff and the partitioning of the total runoff into the lateral flow and surface runoff were physically meaningful. More significantly, SWAT was able to simulate saturation excess overland flow, which is dominant compared to infiltration excess, and it is a distinctive characteristic of paramo catchments. Based on the overall model performance, we conclude that SWAT can reasonably simulate the hydrological response of Andean paramo catchments, and therefore, its application can extend to similar tropical alpine catchments. Nevertheless, the model showed limitations for simulating low flows.