Analysis of Identification and Driving Factors of Ecological Base Flow Noncompliance in Major Rivers of China

Ecological base flow (EBF) is essential in maintaining the basic functions of river ecosystems, and its satisfaction evaluation and driving analysis are vital in water resource management. Most previous research has been focused on EBF target setting, and there has been a lack of analysis of river EBF satisfaction evaluation and the driving forces of noncompliance. Thus, we proposed new indicators to represent the deviation degree and analyzed the temporal and spatial characteristics of the EBF situation in China over a long time. Then, we improved the methods by incorporating some of the new indicators, which are more suitable for national EBF satisfaction evaluation. The main conclusions are as follows. 1) From 2009 to 2018, the EBF satisfaction status in China generally improved, but the overall situation was not optimistic. The Liaohe, Haihe, and Huaihe River Basins had the worst EBF satisfaction status. The poorest record of EBF protection appeared in the second quarter. The characteristics of noncompliance were expressed as the high concentration of noncompliant days in a year, high frequency of anthropogenic interruption, and significant damage depth. 2) National annual EBF compliance evaluation methods were improved by combining the new indicators with previous methods and recommended by comparing their suitability for different methods. 3) Chinese EBF noncompliant stations were identified. Seasonal water use conflict and high water withdrawal were the main driving forces of noncompliant stations. The results provide reference information for the management and protection of the EBF in China.