Abstract. In the middle and lower reaches of inland river basins of arid regions, human-intensive exploitation directly determines the distribution patterns of plants in arid areas and further determines the patterns of water use and the water cycle in arid regions. However, human activities on vegetation water utilization and the influence of the water cycle process and mechanism are not clear. In this study, seven observation systems were set up to collect samples in the mountainous, oasis and desert areas of the Shiyang River Basin, an arid inland river in central Asia. In order to quantitatively assess the contribution of different potential water sources to plants, stable isotopes of various water bodies in different geomorphic units of the basin were analyzed. The results showed that precipitation and soil water were the main sources of forest trees in mountainous areas, and the farmland vegetation in the middle and lower reaches of the oasis mainly absorbed soil water supplied by irrigation. The desert area forms vegetation in the ecological water transport area, and vegetation mainly absorbs soil water, lake water and groundwater formed by ecological water transport. On the whole, the water use patterns of plants in mountainous areas are not affected by human activities fundamentally, the oasis area is mainly affected by irrigation activities, and the inland river terminal lake area is mainly affected by ecological water transport. Human activities determine the water use patterns in the middle and lower reaches of inland rivers in arid areas.

Abstract. The water cycle has been hampered by urban development and the changes it has made to natural surfaces, especially in arid regions with scarce water supplies. Urbanization has a significant hydrological impact because of the high water demands of urban populations and economic factors. We set up an observational system close to Wuwei City, which is situated in the Shiyang River Basin, to research the effects of urbanization on isotope dynamics within the basin. We sought to clarify any perceptible changes in isotopic patterns by the methodical collecting and analysis of water samples from various water sources. According to our research, landscape dams in urban areas have a substantial impact on the evaporation and penetration of surface water. We have also observed a weaker connection between precipitation, surface water, and groundwater in urban areas, as compared to non-urban regions. Also, our research has demonstrated that metropolitan areas have a quicker catchment cycle and a quicker conversion of rainfall to runoff. These results have important ramifications for managing water resources and urban planning since they offer important insight into the hydrological dynamics of urban areas. In dry regions, where care must be made to the loss of water resources owing to landscape dam evaporation, the barrier impact of urbanization on water body connection is particularly severe.