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

Abstract

水文改变指标（IHA）能够较为全面地描述水文状况，在评估水文情势改变及其生态系统影响方面具有广泛的应用.尽管该指标体系较为完善，但是数量众多的水文变量仍然存在信息冗余问题.根据洞庭湖城陵矶水文站1955-2014年的径流量数据，采用主成分分析（PCA）筛选了生态最相关水文指标（ERHIs），结合ERHIs改进了用于估算环境流量的变化范围法（RVA），并将其应用在洞庭湖出口的环境流量估算中.基于PCA选取了年最大90日流量、年最小3日流量、年最小流量出现时间、3月流量、6月流量、流量逆转次数和低流量年内平均历时7个变量作为洞庭湖出口的ERHIs.纵向和横向的对比分析都表明选取的ERHIs是合理的.ERHIs不仅有效缓解了IHA的冗余性问题，还有利于抓住最关键的生态水文变量.根据ERHIs改进的RVA方法在设定洞庭湖出口环境流量时，极大地简化原来的众多管理目标，对生态水文研究、水资源管理和生态保护都具有重要的参考价值和借鉴意义.;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.