Optimal selection of the most ecologically relevant hydrologic indicators and its application for environmental flow calculation in Lake Dongting

The method of indicators of hydrologic alteration (IHA) provides a relatively comprehensive way to describe the full range of hydrological regimes and is used globally to assess hydrological alteration and its ecosystem influence. This method is relatively sound, while it still has potential redundancy problems caused by a large number of variables in it. Therefore, the principal component analysis (PCA) was used to select the most ecologically relevant hydrologic indicators (ERHIs), based on the flow data at Chenglingji, a standard observation station of Lake Dongting, from 1955 to 2014. The method of range of variability approach (RVA) was improved by the selected ERHIs and was used to estimate environmental flow in the outlet of Lake Dongting. Based on the results of PCA, seven ERHIs were selected: annual maximum 90-day flow, annual minimum 3-day flow, Julian date of each annual 1-day minimum, March flow, June flow, number of hydrologic reversals and median duration of low pulses. It was proved that the seven selected ERHIs were reasonable with the comparison to previous studies and the redundancy analysis. ERHIs not only reduce the redundancy of IHA but also help to grasp the key component of eco-hydrological variables. Moreover, the improved RVA method greatly simplified the original management targets in estimating environmental flow in the outlet of Lake Dongting. This study is of great value and significance for eco-hydrological research, water resources management and ecological protection. © 2018 by Journal of Lake Sciences.