Join tecological operation optimal strategy of control and re-regulation reservoirs: A case study of Three Gorges-Gezhouba cascade reservoirs

Abstract

全球主要河流已成为受梯级水库控制的人工调节系统.河流鱼类作为淡水生态系统的重要组成部分，在人类对河流水能资源开发利用的进程中，面临着种群退化、多样性丧失的巨大胁迫.水库生态调度是在鱼类关键生命期人为营造满足鱼类需求的水文水动力条件，减缓水库不利生态影响的一种生态环保措施.然而，在生态调度的实践过程中，受水库不同运行方式影响，下游水流条件在局部时段存在与鱼类需求相悖的情况，有进一步提升空间.本文选择了当前世界上规模最大的三峡水电站和其下游的葛洲坝水电站为案例，建立了梯级水库联合调度模型，模拟分析了梯级水库协同运行改善下游河道鱼类繁殖条件的可行性，并探讨了优化调整策略.结果表明，目前三峡、葛洲坝梯级水库生态调度的运行方式，大多数情况下仅通过葛洲坝水库小时尺度的精细调度，就可实现下游四大家鱼产卵繁殖所需的小时尺度连续涨水目标，并可一定程度提升发电出力，达到生态与经济共赢的良好成效.研究结果表明葛洲坝水库有能力在生态调度的特定时期内充分运用反调节库容调节三峡日出库流量过程，可为梯级水库生态调度的优化实践提供积极参考.;The major rivers across the world have become artificial regulation systems controlled by cascade reservoirs. River fish, as an important part of freshwater ecosystems, are under threat of population degradation and biodiversity loss in the process of development and utilization of river water energy resources. The ecological operation of the reservoir is eco-environmental protection to alleviate the negative impact on ecosystems, which artificially creates hydrological and hydrodynamic conditions to meet the requirement of fish during key life periods. However, based on ecological operation practical experience, there are circumstances where downstream flow conditions are inconsistent with the fish requirement in local periods affected by different operation conditions of reservoirs. That means the ecological operation still needs improvement. This paper takes the Three Gorges Dam, the world's largest power station, and the downstream Gezhouba Dam, as a case study, builds a joint operation model of cascade reservoirs, simulates and analyzes the feasibility of the cascade reservoirs to improve the spawning conditions of fish in the downstream river reaches under joint operation and discusses the optimal strategy. In most cases, the target of continuous flow rising for hourly timescale can be accomplished only by the hourly exquisite operation of Gezhouba reservoir, which is required for the four major Chinese carps spawning downstream of Gezhouba Dam. What's more, the hydropower generation output can be improved to a certain extent, thus achieving win-win progress of ecology and economics. The results of this paper show that Gezhouba reservoir can adjust the daily discharge process of the Three Gorges Reservoir by the re-regulation during a specific period of ecological operation, which may function as a useful reference for the optimization practice of ecological operation of cascade reservoirs.