Study on the Influence of Rapid Urbanization on the Hydrological Characteristics of Xi’an City

The rapid development of urbanization in Xi’an, along with the rapid expansion of the city scale, has significantly altered the underlying surface conditions of the city. This has led to profound changes in the water cycle processes, including rainfall, infiltration, and runoff. These changes have directly affected the pattern and triggered a series of issues related to urban hydrology and water resources. Therefore, it is necessary to study the impact of Xi’an’s urbanization on the underlying surface and hydrological characteristics of the basin. It is found that the decreasing rate of rainfall in flood season is significantly greater than that of annual rainfall from the annual rainfall increase coefficient and the difference rate of rainfall in the suburbs, which indicates that the influence of urbanization on the rainfall in flood season is greater than that of annual rainfall. Urbanization also increases the probability of heavy precipitation in urban areas. The mutation analysis of annual rainfall days by the M–K test and sliding T test showed that the mutation occurred in 1990 and 2009. Based on the monthly runoff data of the Feng River and Ba River hydro-logical stations from 1956 to 2015, it was found that urbanization caused the in-crease in runoff in winter and the a decrease in runoff in spring. The mutation analysis of rain and runoff from the Feng River and Ba River revealed that both mutation points occurred in the late 1970s and the middle and late 1990s, precisely during the period of urbanization development.