水电站运行对库尾鱼类生境影响研究

Research on the impact of hydropower plant operation on fish habitat at the reservoir tail

摘要

【目的】水电站运行不仅改变了下泄流量影响下游河段生境适宜性，同时坝前水位波动将改变库尾变动回水区的生境特征。通过阐明不同来水情况下水电站运行对水电站库尾变动回水区鱼类产卵场适宜性的影响规律，为调节性水电站鱼类繁殖期生态调度运行提供参考与借鉴。【方法】以黄河上游多年调节水电站龙羊峡运行实况监测数据为例，以龙羊峡库尾野狐峡产卵场为鱼类保护生境，选取河段内保护鱼类极边扁咽齿鱼为研究对象，构建鱼类栖息地模型，并引入加权可利用面积WUA(Weighted Usable Area)和分裂指数SPLIT(Splitting Index),定量评估鱼类繁殖期水电站调度运行方式的改变对库尾鱼类生境适宜性的影响。【结果】结果显示：现行年内运行方式对库尾鱼类生境的影响表现为WUA先增大后减小，产卵生境分裂指数SPLIT逐渐增大，4月上旬至5月下旬WUA增加74.43%,5月下旬至6月下旬WUA减小52.39%,4月至6月SPLIT增加221.94%。WUA和SPLIT变化趋势不一致的原因在于，WUA反映了产卵场面积的变化，而SPLIT则反映了产卵场的整体性与碎片化程度。4月上旬至5月下旬，流量增加和水位下降导致产卵场面积增加，但因地形和水流变化使整体性变差，WUA增加、SPLIT增加；而5月下旬至6月下旬，随着流量进一步增加和水库运行水位抬升，适宜产卵的区域减少且破碎化加剧，WUA减小，而SPLIT增加。【结论】结果表明：龙羊峡年内运行显著影响SPLIT与WUA,后续开展电站生态调度运行，可有效地改善库尾回水区鱼类产卵场的生态水文过程和水动力条件。

Abstract

[Objective] The operation of hydropower plants not only alters the suitability of downstream river habitats through changes in discharge but also affects the habitat characteristics of the fluctuating backwater area at the reservoir tail due to water level fluctuations in front of the dam. By clarifying the effects of hydropower plant operation on the suitability of fish spawning habitats in the backwater area under different water inflow conditions, this research aims to provide a reference and guidance for ecological scheduling during fish spawning periods in regulating hydropower plants. [Methods] Using the operational data from the Longyangxia hydropower plant in the upper Yellow River as a case study, this research focused on the Yehuxia spawning ground at the reservoir tail as a fish protection habitat. Platyharodon extremus was selected as the target species. A fish habitat model was constructed, and the Weighted Usable Area(WUA) and the Splitting Index(SPLIT) were introduced to quantitatively assess how changes in hydropower plant scheduling affect habitat suitability during fish spawning periods. [Results] The result indicated that the current annual operational mode affected the fish habitat at the reservoir tail, with the WUA first increasing and then decreasing, while the SPLIT of the spawning habitat gradually increased. From early April to late May, the WUA increased by 74.43%. From late May to late June, the WUA decreased by 52.39%. From April to June, the SPLIT increased by 221.94%. The inconsistent trends of WUA and SPLIT were due to the fact that WUA reflected changes in the spawning habitat area, while SPLIT represented the integrity and fragmentation of the spawning area. From early April to late May, increases in flow and decreases in water level expanded the spawning area. However, changes in topography and flow patterns worsened the overall integrity, causing both WUA and SPLIT to increase. From late May to late June, as flow levels continued to rise and the reservoir water level increased, the suitable spawning areas shrank and became more fragmented, leading to a decrease in WUA and an increase in SPLIT. [Conclusion] The result indicate that the annual operational mode at Longyangxia significantly affects both SPLIT and WUA. Further ecological scheduling of the hydropower plant can effectively improve the ecological hydrological processes and hydrodynamic conditions of fish spawning habitats in the reservoir tail backwater area.

关键词

水电站调度运行 / 库尾回水区 / 鱼类生境适宜性 / 加权可利用面积 / 分裂指数 / 影响因素

Key words

hydropower plant scheduling / reservoir tail backwater area / fish habitat suitability / weighted usable area / splitting index / influencing factors

基金资助

国家自然科学基金项目(5240091102)