Response and Prediction of Runoff to Land Use Change in Kuye River Basin Based on SWAT and PLUS Models

[Objective] The study is aimed at revealing the response of runoff to land use change in the Kuye River Basin and predicting future runoff change. [Methods] Taking the Kuye River Basin as the study area, based on the SWAT and PLUS models, the changes of runoff under different land use scenarios were quantitatively analyzed by using the land use data of 2000, 2005, 2010, 2015, 2020 and the data of 2025 and 2030 that were predicted from the natural development scenario. [Results] (1) The R2 and NS of the SWAT model during the periodic and validation periods were greater than 0.7. The overall accuracy of PLUS model was 0.877 4, and the Kappa coefficient was 0.802 1. The two models had good applicability in the Kuye River Basin. (2) From 2000 to 2020, forest land and construction land increased by 102.92 and 600.90 km2, respectively, while cultivated land, grassland, water area, and unused land decreased by 277.15, 366.25, 40.44 and 19.98 km2, respectively. (3) The average annual runoff depth in the Kuye River Basin presented a spatial distribution pattern of “lower in the upper reaches, higher in the lower reaches, lower in the west, and higher in the east”. (4) Changing land use data while ensuring that other input data remains unchanged, the results of scenario analysis showed that the decrease of forest land and grassland area would promote runoff, and the increase of construction land area would also promote runoff. (5) Under the natural development scenario, there was no significant change in the spatial distribution pattern of land use in the Kuye River Basin in 2025 and 2030, and the land use was still dominated by cultivated land and grassland, with the average annual runoff increasing by 3.21% and 5.00%, respectively, compared with 2020. [Conclusion] There was a close relationship between land use and runoff change. From the perspective of scenario analysis, forest land and grassland inhibited runoff, while construction land promoted runoff. Under the future natural development scenario, runoff increased with land use change. The research could provide scientific basis for the optimization of land use structure and rational planning of water and soil resources in the Kuye River Basin.