Simulation of water resources in ungauged region- case study in Nam Ou River Basin, Laos

• The hydrological parameters of Nam Ou River Basin were transplanted using the constructed VIC model, and the water resources of each three-level area in Nam Ou River Basin from 1981 to 2010 were simulated to provide technical support for water resources management without affecting the local ecological environment, thus promoting the local economic and social development. Hydrological studies in ungauged regions have garnered significant interest in recent research. This paper presents the development of a VIC model utilizing topographic, vegetation, soil, and climate data. The model parameters were calibrated and validated with measured flow data from the watershed. Through parameter transplantation, the calibrated parameters were applied to simulate the spatial distribution and annual allocation process of water resources in the Nam Ou River Basin. The analysis revealed that the spatial distribution of water resources and runoff coefficients closely aligns with the spatial distribution of precipitation, indicating a strong correlation between water resources and precipitation in the basin. From 1980 to 2010, the average water resources for the basin were estimated at 16.4 billion m3, with a rainy period from May to September. August recorded the highest water resources, while the dry period from December to February saw the lowest water resources in February. Upon evaluating the results’ robustness, it was concluded that the VIC model’s simulation accuracy is high, making it a valuable tool for future research in areas with insufficient or absent data.