## 1 Introduction  
Global climate change and human-activity-induced changes in water resources have had a tremendous consequence on the ecological environment and socioeconomics, thus attracting attention from the international community [1, 2]. This is particularly obvious in arid and semi-arid regions with fragile regional ecosystems [3; 4; 5]. The evolution and relationship between hydrological processes and ecosystems in arid and semi-arid regions in a continuously changing environment is not clearly understood. The present research on hydrology-ecology mainly focuses on the relationship between a certain hydrological process factor and an ecological indicator, without focusing on the relationship between the linkage between the whole hydrological process factor and the ecosystem quality. Therefore, it is particularly important to understand the relationship between the whole hydrological processes and ecosystem quality (EQ) in arid and semi-arid regions and to design related policies. The results of the study can deepen the understanding of the relationship between hydrological processes and ecosystems in arid and semi-arid regions and provide a reference for the sustainable use of water resources and environmental protection in the region. As arid and semi-arid regions are deeply inland and far from the ocean, not only is data about them deficient but the measurement data from meteorological and hydrological stations in regions such as the Ulagai River Basin and Xilin River Basin are lacking, [6]. Therefore, hydrological models and remote-sensing monitoring have become important monitoring tools. The Soil and Water Assent Tool (SWAT) model is a semi-distributed hydrological model developed by the United States Department of Agriculture and the Agricultural Research Service. The SWAT model can simulate the hydrological cycle of a basin and quantify the response of basin hydrological processes to changing environments [7]. This model is popular given its systematic and precise simulation and computational capabilities. Forecast simulations have been performed in several basins around the world, and they have achieved excellent results [6; 8]. For example, [PERSON] et al. [9] used a modified SWAT model to simulate the extent of changes in hydrological process factors for different land-use types. The results of their study showed that the conversion of barren land to agricultural land handled resulted in a decrease in surface runoff and water production, whereas the groundwater flow, lateral flow, and evapotranspiration (ET) had increased. [PERSON] et al. [10] used the SWAT model to evaluate the impact of land use on hydrological processes (ET and streamflow) in the river suite irrigation area. They also evaluated dispersion and river flow, using the SWAT model. Being a major data source for the study of several ecological and environmental issues, such as grassland degradation and soil sanding, remote-sensing data facilitate the quick identification of spatial and temporal changes as they relate to environmental quality [9]. [PERSON] et al. [11] used remote-sensing data concerning biomass and vegetation cover to study if and how the status of EQ in Inner Mongolia changed from 2000 to 2010 and explore whether and how it was affected by climate change and human activities. [PERSON] et al. [12] explored the spatial and temporal characteristics of environmental evolution in inland river basins in the arid regions of Northwest China with the help of integrated remote-sensing-related indicators. However, previous studies have mostly focused on specific years and mostly taken into account aspects such as ecosystem service function, stability evaluation, ecosystem health evaluation, and ecosystem pattern. Only a few of these studies have carried out an integrated evaluation of EQ changes in arid and semi-arid regions over a long period. Recently, national and international researchers conducted several studies on the relationship between the hydrological cycle and EQ [13; 14]. [PERSON] et al.