Impact on discharge modelling using different spatial and temporal resolution scenarios in South of Chile

Abstract

Despite ungauged basins exist across countries of a wide range of incomes, assessing water resource availability is an essential issue in low-income zones with less dense hydrologic measurement networks. In a megadrought context, hydrological resources availability is critical in the central south of Chile, leading to water scarcity problems for the population. We develop a one-way coupled discharge model using the Weather and Research Forecast (WRF) and Variable Infiltration Capacity (VIC)/routing model to estimate surface water availability along the basin and subbasins. We studied the Biobío basin in Chile (∼37° S) because of its low spatial density discharge measurements as a case of study. We compare discharge variations simulated between two datasets and in-situ high temporal resolution measurements between the years 2005–2006. Our results show that discharge is unsuitable for a mid-scale basin using atmospheric products over 12 km of spatial resolution. However, our simulations showed high efficiency (Nash Sutcliffe over 0.75) and low RMSE values (less than 40 m3s-1 in most cases) in daily and tri-hourly simulations at 4-km spatial resolution. The percentual root mean square error (pRMSE) improved from the worst scenario (110% in SC1) up to 37% in the best scenario (SC3), showing that the coupled approach is suitable for basins in the south of Chile. These results provide a temporal-spatial basis for improving water resources management in poorly gauged basins in the south of Chile, as is common in South America. Our analysis will contribute to a real-time flow modeling system development for the Biobio basin. Future developments will contribute to surface water availability in a water scarcity context.