Subjects: Geosciences >> Hydrology submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： The Ulagai River Basin in Inner Mongolia is a typical inland river basin in the pastoralist grasslands of the arid and semi-arid regions with extremely fragile ecosystems, and climate warming and human activities can directly affect hydrological changes. In this study, we used the improved SWAT (Soil and Water Assessment Tool) hydrological model, M-K trend test, precipitation-runoff double accumulation curve, and scenario analysis to systematically analyze the spatial and temporal characteristics of runoff in the Ulagai River Basin from 1981 to 2020 and to quantify the differences between climate change and human activities on runoff in different periods and river sections. The differences in the impact of climate change and human activities on the runoff in different periods and river sections were quantified. The results show that the SWAT model significantly impacted runoff in the Ulagai River Basin from 1981 to 2020. The results show that the SWAT model has good applicability in the Ulagai River Basin, with NSE and R2 above 0.62 and PBLAS less than 18.8% for both the periodic and validation periods. Under the warm and dry trend of the basin in the past 40 years, the runoff volume decreased significantly in the upper, middle, and lower reaches, then a sudden change occurred in 2000. Considering the contribution of human activities such as climate change and overgrazing, blind reclamation and construction of water conservancy reservoirs to the change of runoff in the basin was 95.84% and 4.16%, respectively. Also, the contribution of human activities to different river segments in the basin varied, with 1.69%, 4.36%, and 5.03% from upstream to downstream. The contribution rates also differed significantly across different periods, from 88.26% in 1980 to 25.47% in 2020. The trend and magnitude of runoff changes due to different human activity patterns in different periods also differed. This study’s results can provide a reference basis for the sustainable use and rational scheduling of water resources in the inland river basin of pastoral grasslands.
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