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.