Analysis of the hydrological conditions based on hydrological model in a data-scarce basin: A case study in the Yongding River Basin

The hydrological conditions are key factors in ensuring the health of water ecosystems. The lack of runoff data constrains the assessment of the basin's evolutionary pattern of the eco-hydrological conditions. The Yongding River Basin (YDRB) is a typical water-scarce basin in northern China, where the changing environment has led to widespread water scarcity and ecosystem degradation problems. In response to the shortage of information at the upper reaches of the YDRB at the Xiangshuibao gauging station, this study adopted a distributed hydrological model, WetSpa, to simulate the daily runoff data in this station from 1960 to 2019. Then, Indicators of Hydrologic Alteration (IHA) was used to identify the most ecologically relevant hydrological indicators (ERHIs) and further determine the "true" eco-hydrological variation point in the basin. Finally, the evolution rule of the eco-hydrological conditions in the basin was analyzed and the overall hydrological alteration degree of the Xiangshuibao Section was determined. The results showed that the rising rate, decline rate, annual maximum 1-day flow, annual minimum 1-day flow, annual maximum flow occurrence time, and July flow were the ERHIs. The variation period was from 1980 to 1986. Except for the annual maximum 1-day flow and decline rate were moderate variation indicators, all others were low variation indicators. The overall hydrological variability of the Xiangshuibao section was low. The results of this study were intended to provide a reference for ecological management construction in the YDRB and other similar areas.