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 Biobio basin in Chile (similar to 37 degrees 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 trT 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.