Evaluating the Impact of Power Station Regulation on the Suitability of Drifting Spawning Fish Habitat Based on the Fuzzy Evaluation Method

Abstract

Ecological regulation is an important means of reservoir adaptive management, but its effective evaluation faces two major difficulties: the response mechanism of fish spawning behavior is not completely clear, and how to establish the feedback regulation relationship of hydrological processes to improve the river environmental state is unknown. Based on a long-term series of early fish resources, hydrology, water temperature, and meteorology data, this research clarifies the fish spawning habitat requirements in the regulating environment, determines the habitat suitability evaluation index system and evaluation criteria, reveals the temporal and spatial variation characteristics of fish  habitat suitability under power station regulation based on the fuzzy logic method, provides feedback to the existing regulation scheme, and proposes suggestions for sustainable adaptive management of the reservoir. The temporal and spatial variation characteristics of the habitat suitability of spawning grounds are the comprehensive differences among multiple objectives and factors. The specific manifestation is that the habitat suitability of each river section decreases after impoundment, especially in May, which is related to the delay of water temperature changes under reservoir regulation. The decrease in the suitability of the YibinYB river section is most affected by the impoundment regulation of the Xiluodu Reservoir (XLDR) and Xiangjiaba Reservoir (XJBR), while the Luzhou(LZ) river section is affected by the inflow of the tributary Minjiang River (MJ), which reduces the suitability difference before and after impoundment. The Jiangjin(JJ) river section is less affected by the regulation of the XJBR and is greatly affected by tributaries and rainfall. Affected by the cumulative impact of the sustainable development of upstream cascades, how to adjust new regulation strategies under the new boundary and new situations in the future scenario is the focus of reservoir adaptive management. This research can provide technical support for the management of cascade reservoirs under future scenarios.

Keywords: reservoir ecological regulation, adaptive management, drifting spawning fish, habitat suitability evaluation, fuzzy evaluation