Characteristics and Adaptability Assessment of Commonly Used Ecological Flow Methods in Water Storage and Hydropower Projects, the Case of Chinese River Basins

Lejun Ma,Hanwen Zhang,Changjun Qi,Xinnan Zhang,Huan Wang

doi:10.3390/w11102035

Abstract

The construction and operation of water storage and hydropower projects affects the structure of water ecosystems of downstream rivers, and the establishment of ecological flow in rivers below the water storage and hydropower projects has significant impacts on maintaining the stability of river ecosystems. A database was established based on 2000–2017 environmental impact assessment (EIA) reports on water storage and hydropower projects in China and ecological flow (e-flow) methods, and the three widely used e-flow methods for water storage and hydropower projects in China were identified on the database. Furthermore, an ecological flow satisfaction degree model was used to evaluate the methods using long series of historical hydrological data from the hydrological stations in the Yellow River basin, the Yangtze River basin, and the Liao River basin. The results showed that hydrological methods are the type most often used for water storage and hydropower projects in China, including the Tennant method, the minimum monthly average flow with 90% guarantee rate method (Mm9M method), and the measured historical minimum daily average flow rate method (MDM method). However, the ecological flow methods selected are not significantly different among different basins, indicating that the selection of ecological flow methods is rather arbitrary, and adaptability analysis is not available. The results of the ecological flow satisfaction model showed that the Tennant method is not suitable for large river basins. The results of this study can provide technical support for establishment and management decisions surrounding ecological flow.

Highlights

A river ecosystem is the unity of material circulation and energy circulation between organisms and their environments and is a continuous system that relies on the hydrological regime [1,2].The socio-economic development of human beings is closely related to rivers
The results indicated the Tennant method was widely used to calculate the e-flow of water storage and hydropower projects in various basins, its ecological satisfaction degree at all of the stations were zero
We found that the French Rural method was used eight times; this result surprised us because this contradicts the lower limit of the e-flow specified in the guidelines, which has no reference significance in the calculation of the e-flow of water storage and hydropower projects in China

Summary

Introduction

A river ecosystem is the unity of material circulation and energy circulation between organisms and their environments and is a continuous system that relies on the hydrological regime [1,2]. The socio-economic development of human beings is closely related to rivers. Water 2019, 11, 2035 of water resources, humans have built a large number of reservoirs, dams, and water diversion projects on rivers. The World Wildlife Fund (WWF) has surveyed 12 million kilometers of rivers worldwide and assessed their mobility, and their results show that approximately two-thirds of the surveyed rivers have no free flow. In the United States, Europe, and other developed countries, long, free-flowing rivers do not exist; in addition, the rate of decline in the number of freshwater animals and plants is twice the rate of decline in the number of species on land and at sea [3].

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Conclusion