Spatiotemporal evolution pattern and characteristics of hydrological functions of key hydrological elements in the Xiliao River Basin, China

The Xiliao River Basin is an important economic development area and ecological barrier in Northeast China. In recent years, it has experienced the serious degradation of hydrological function. Based on the hydrometeorological data, remote-sensing imagery, and water resource utilization data of the basin, the function evaluation model and standard deviation ellipse model were used to construct a hydrological function index system and evaluation model that combined ecological and socioeconomic indicators to analyse the evolution characteristics of hydrological functions. The results showed that the centre of precipitation function of the basin had shifted eastward; the evapotranspiration function was strong and showed an increasing trend in the hilly area in the upper reaches, watercourses, waters and their surrounding areas in the middle reaches, and most areas in the lower reaches; and the surface water function in the middle and lower reaches of the basin had weakened sharply since the beginning of the twenty-first century, and the degradation reached 70%. The groundwater function was stronger in the lower reaches than in the upper and middle reaches, and the degradation of groundwater function in the urban agglomeration area was is degraded by 10–30%. The overall hydrological function of the basin was higher in the southwest and lower in the east, and its degradation degree and scope in the urban agglomeration areas was further deepened and has expanded since 2000. This study enriches the research results on hydrological functions and provides a basis for the restoration and construction of the hydrological functions in the basin.