淮河流域环境流变化及其对洪泽湖鱼类栖息地的生态影响

为分析淮河流域环境流要素的变化趋势及其对洪泽湖鱼类栖息地的生态影响,以淮河中下游河段为研究区,采用IHA法,将蚌埠水文站1950—2015年径流序列划分为2002年蚌埠闸扩建前后两个时期,采用5种流量事件筛选出32种环境流评价指标,分析了水文变异条件下5种环境事件的生态效应;以鳜鱼为洪泽湖指示鱼类,综合考虑栖息地限制因子,运用PHABSIM模型得到栖息地加权可利用面积-流量曲线,计算了鳜鱼产卵期的生态流量。结果表明:淮河中下游环境流组成趋于单一化,大洪水事件减少,枯水流量增大,高脉冲流量持续时间缩短,出现次数增加,对下游生态环境不利;洪泽湖鳜鱼4—6月产卵期的最小生态流量为300 m~3/s,适宜生态流量为550 m~3/s;需合理调控环境流,增加鱼类补充和物质循环,并采取湖泊生态修复等措施,维持洪泽湖的生态平衡。

Changes of environmental flow in Huaihe River Basin and its ecological impact on fish habitat in Hongze Lake

In order to analyze the changing trend of environmental flow factors in Huaihe River Basin and its ecological impact on fish habitat in Hongze Lake, IHA(indicators of hydrologic alteration)method was used to study the middle and lower reaches of Huaihe River. The runoff series of Bengbu Hydrological Station from 1950 to 2015 was divided into two periods before and after the expansion of Bengbu Gate in 2002.32 environmental flow evaluation indexes were screened out by using five flow events. Taking mandarin fish as indicator fish in Hongze Lake and considering habitat restriction factors comprehensively, the area-flow curve of habitat was obtained by using PHABSIM model, and the ecological flow of mandarin fish during spawning period was calculated. The results show that the composition of environmental discharge in the middle and lower reaches of Huaihe River tends to be simplified. The flood events are reduced, the low water flow is increased, the duration of high pulse flow is shortened and the frequency of occurrence is increased, which is harmful to the ecological environment in the lower reaches of Huaihe River. The minimum ecological flow rate of mandarin in Hongze Lake during spawning period from April to June is 300m³/s, and the suitable ecological flow rate is 550m³/s. In order to maintain the ecological balance of Hongze Lake, it is necessary to regulate environmental flow reasonably, increase fish replenishment and material cycle, and take measures such as lake ecological restoration.