梯级电站建设运营对下游水质的影响

Effect on Water Quality at Downstream of the Building and Operation of Cascade Hydro-power Stations

在利水电站库区上游、库区、坝上、坝下布设监测断面,进行为期近2个月的枯水期水质监测,通过分析上下游水质的变化,研究了梯级电站的建设与运营对下游水质的影响。结果表明,各断面COD_(Mn)、DO、NH_3-N、总P均符合Ⅲ类水质标准,无明显大的变化,但随着水流方向呈变差的趋势。由此认为,梯级电站的建设运行,形成梯级水库,流速变缓,大气覆氧能力降低,水中溶解氧下降,导致水体自净能力变差,对污染物的稀释、混合和降解能力减弱,是造成电站下游水质变差的主要原因之一。

The water quality of Jiulongjiang River was continually monitored for nearly two months in the dry season by establishing monitoring sections at the upstream,reservoir area,up-dam and down-dam of the Lishui hydropower station.The influences of the building and operating of the cascade station on the water quality of the downstream was further investigated by analyzing the variation of the water quality between the upstream and the downstream of the reservoir.The results showed that the values of COD_(Mn),DO,NH3-N and the total P amounts at all the sections were in accordance with GradeⅢwater quality,but the water quality changed worse along the stream. From this,it was supposed that the construction and operation of the hydropower station as well as the formation of the cascade reservoir slowed down the flow rate of the stream,decreased the enriching oxygen ability of the atmosphere and the dissolving oxygen capacity of the water,further reducing the self-purification ability of the water and the dilution,mixture and degradation functions to the pollutants,which might be one of the main reasons to explain why the water quality of the downstream of the station deteriated.