Assessment of Gridded Precipitation Products for Streamflow Simulation in an Urban Andean Watershed in Colombia using SWAT

Hydrology modeling is a useful tool for comprehending the impacts of climate variability and climate change on water resources management. Precipitation is a key variable for forcing and calibrating hydrological models as well as simulating the streamflow response in a river basin, thus its reliable and accurate representation is needed for describing different hydrological processes. Traditionally, precipitation inputs used in hydrological modeling come from ground-based observations. However, these measurements have limitations related to the uneven and sparse distribution as well as the limited temporal coverage of the gauging networks, especially in developing countries. The Gridded Precipitation Products (GPPs, henceforth) and weather radars are alternative sources to overcome this limitation since they provide continuous spatio-temporal precipitation estimates at different scales. Here, we assess the potential to apply GPPs and radar estimates for simulating daily and monthly streamflow using the Soil Water Assessment Tool (SWAT) in the middle watershed of the Aburrá River, located in the Colombian Andes. Our objective was to identify alternative precipitation sources for hydrological modeling to compare with rain gauge-based in The Aburrá valley, where an effort has been made for real-time monitoring. The precipitation data includes the Climate Hazards Group Infrared Precipitation with Stations (CHIRPSv2), Multi-satellite Retrievals for Global Precipitation Measurement (IMERG), and the SIATÁs meteorological radar. Our results showed that the model produced appropriate monthly streamflow simulations with all GPPs precipitation products, while the model performance to simulate daily streamflow was lower. Overall, the meteorological radar produced the best simulation results based on values of the Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R2), and bias (PBIAS), outperforming CHIRPSv2 and IMERG results particularly at daily time scale. Finally, these findings support the use of GPPs and radar for hydrological modeling applications for government decision makers of the Area Metropolitana del Valle de Aburrá (AMVA).