小浪底水库排沙对下游鱼类的影响研究

Impact of sediment flushing of Xiaolangdi Reservoir on downstream fish

采用现场调查和室内实验相结合的方法研究了黄河小浪底水库排沙期间下游河流出现鱼类死亡现象的原因。2010年度小浪底水库排沙期间,下游出现了高含沙水流过程,伴随出现了鱼类死亡现象,调查发现受影响鱼类有5目5科11种。水库排沙期间的含沙量、溶解氧变化过程的现场调查及室内实验结果表明,小浪底水库排沙时细颗粒泥沙含量较高,堵塞和损坏鱼鳃是导致鱼类死亡的原因之一。当含沙量大于80kg/m3时,水体溶解氧下降至鱼类生存所需下限2mg/L以下,鱼类在短时间内缺氧而死亡;当含沙量低于60kg/m3时,根据现场调查结果及相关人员经验判断水库下游河道内不会出现鱼类死亡漂移现象。水库排沙期间,下游河道水体的含沙量与溶解氧浓度具有较好的相关性,即河道水体的溶解氧浓度随着含沙量的增加而减少,可通过控制出库含沙量及其持续时间减轻水库排沙对鱼类的影响。

During sediment flushing of the Xiaolangdi Reservoir in the Yellow River,fish deaths were usually observed in downstream river reach.Explains for the phenomenon were studied by field survey and laboratory experiments.In the process of sediment flushing in 2010,high concentrated sediment flow played an important role in the destruction of habitat.Investigation showed 11 fish species from 5 families and 5 orders were affected by the lethal concentration.It could be demonstrated,by variation process of sediment concentration and dissolved oxygen from field and laboratory study,that high concentrated fine sediment flow,which caused the clogging of fish gills,is one of the dominant reasons for fish mortality.When the sediment content was higher than 80kg/m3,the dissolved oxygen concentration fell below 2mg/L which was lower than the limit for fish living requirements.In this circumstance,fish went to death in a short period caused by hypoxia.While sediment content was lower than 60kg/m3,by survey and experience,there were no deaths of fish in downstream river reach.There is a direct correlation between DO and sediment concentration downstream of the reservoir during sediment release period,which means that DO would decrease with the increase of sediment concentration.Thus,through reasonable and proper operation,sediment concentration and duration of dam flushing could be regulated to relieve adverse effects on fish.