Abstract: West Liao River Basin (WLRB) is a typical region that is fragile and sensitive ecologically. It is important to study the impact of its land use changes on freshwater provision and flood regulation for sustainable utilization of its water resources and ecological protection. This paper presents an analysis on the spatial and temporal evolution characteristics of freshwater provision and flood regulation services in the basin in 1990-2020, using a distributed hydrological model (GBHM) developed for WLRB, in combination with an index-based ecosystem service approach. We discuss in depth the impacts of the changes in different land types－such as grassland, farmland and forest－on the two eco-hydrological service functions. The results show that in this period, overall freshwater provision services decreased significantly (P < 0.05), while flood regulation services increased significantly (P < 0.05). Both services are higher in the downstream than those in the upstream. In the period of 2005-2020, freshwater provision services in most sub-watersheds were 0% - 42% lower than those in its previous period, while flood regulation services were 0% - 73% higher than the previous values. In representative sub-watersheds, the decreases in grassland and farmland areas and the increase in forested land area resulted in a decrease in freshwater provision services, but enhanced flood regulation service functions to a certain degree.

Key words: West Liao River basin, land use, freshwater provision service, flood regulation service, distributed hydrologic model