|Effects of Daily Peak-shaving on Fish Habitat Downstream of Wudongde Hydropower Station
|中文关键词:裂腹鱼类 日调峰 生态调度 生态流量 乌东德电站
|英文关键词:Schizothoracine fishes daily peak-shaving ecological operation ecological flow Wudongde hydropower plant
| 日调峰是乌东德水电站日常运行的主要出力约束和调度目标。为了探讨电站调度引起的出库流量大幅涨落对下游生态环境的不利影响，采用河道内流量增量法，通过构建二维水动力模型，研究了乌东德水电站日调峰引起的下游河段水文水动力条件波动对裂腹鱼类繁殖期栖息地适宜性的影响，并分析了2023年电站基荷发电生态调度试验效果。结果表明，乌东德电站下泄流量低于1 160 m3/s，坝下江段裂腹鱼类潜在产卵场面积相对较大；流量高于2 000 m3/s，裂腹鱼类潜在的产卵场面积显著减少。电站日调峰结束时，出库流量降幅越大，裂腹鱼类潜在产卵场脱水面积及鱼卵脱水风险越大。乌东德电站基荷发电生态调度期间，坝下江段裂腹鱼类潜在产卵场的加权面积有所减少，但潜在产卵场和鱼卵早期的脱水风险显著降低。为提高繁殖期裂腹鱼类生境适宜性和持续性，有必要进一步减少电站日调峰频率，降低出库流量至适宜区间。
| Daily peaking is the main output constraint and scheduling goal for daily operation of the Wudongde hydropower plant, but the sharp rise and fall of reservoir outflow caused by scheduling has also adversely impacted the downstream aquatic habitat. In this study, Schizothoracinae were selected for a case study, and we analyzed the effects of fluctuating hydrological and hydrodynamic conditions caused by daily peaking at Wudongde hydropower plant on the physical habitats of Schizothoracine species during spawning season. Additionally, we analyzed the effectiveness of ecological operation based on baseload-power-generation at Wudongde hydropower plant in 2023. The aim of the study was to provide a reference for optimizing ecological regulation and flow, and support efforts to conserve and restore fish habitat. The river reach studied is from Wudongde Dam to the Pudu River estuary, stretching 37 km. A two-dimensional hydrodynamic model was constructed using the instream flow incremental method, and the hydrological and hydrodynamic conditions of the Wudongde hydropower plant were simulated under eight flow scenarios. Results show that the potential spawning areas (PSAs) of Schizothoracinae were relatively large when the discharge from Wudongde hydropower plant was less than 1 160 m3/s, and the size of the PSAs decreased significantly when the discharge exceeded 2 000 m3/s. When the power plant used daily peak-shaving, the larger the decrease of discharge, the larger the dewatered PSAs, and the higher the egg-dewatering risk. During ecological operation in 2023, based on baseload-power-generation of Wudongde hydropower plant, the time-weighted size of PSAs for Schizothoracine species decreased slightly in reaches below the dam, but the dewatering risk of the PSAs and eggs was significantly reduced. To improve habitat suitability and duration for Schizothoracinae during spawning season, we recommend further reduction in the frequency of peak-shaving and decreased outflow at Wudongde hydropower plant.
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