飞来峡水利枢纽库区动态纳污能力计算研究

Analysis and Calculation of Dynamic Water Environmental Capacity in Feilaixia Reservoir

根据飞来峡水利枢纽库区水流及水质特点,选取不同设计流量,建立二维水流水质模型.通过水槽实验,拟合水质衰减系数与流速的关系曲线,以获取模型水质计算参数.研究结果表明：通过概化排污口排污量与混合带长度响应关系计算,确定各排污口混合带长度在1 300～2 500m之间;在90％最枯月、50％最枯月及多年平均流量水文条件下,飞来峡库区干流水域COD纳污能力分别为162 107.7t、199 220.2t及372 104.3t; NH3-N纳污能力分别为2 757.4t、3 408.4t和6 276.4t;飞来峡库湾的纳污能力远小于库区干流水域,库湾COD纳污能力仅相当于干流的25％,NH3-N纳污能力仅相当于干流的5％;飞来峡库区纳污能力年内逐月差异显著,其中汛期（4～9月）纳污能力较大,COD、NH3-N纳污能力约占全年纳污能力的58％,飞来峡库区年内月纳污能力与月平均流量呈现较好的正相关关系.

According to the hydrological characteristics and water quality of the Feilaixia Reservoir, a 2-D hydrodynamic and water quality coupling model was developed in response to different designed water discharge. And the calculation coefficients of water quality used in the model was attained by the fitting relation curve of water quality degradation coefficient and flow velocity in the laboratory experiment. The re- sults indicate that each sewage discharge outlets can be estimated to demand the mixed zone between 1 300 m and 2 500 m by the calculation of response relationship between pollution amount of outlets and the length of mixed zone. For the dry season with 90% and 50% guarantee fre- quency and multi-year averages of runoff, the water environmental capacity of COD of the Feilaixia Reservoir is 162 107.7 t, 199 220.2 t and 372 104.3 t, and that of NH3-N is 2 757.4 t, 3 408.4 t and 6 276.4 t, respectively. The water environmental capacity in main stream is larger than that in the reservoir bay, wherein the COD and NH3-N receiving capacity of reservoir bay are equivalent to 25% and 5% of the main stream, respectively. There are significant differences in monthly water environmental capacity of the Feilaixia Reservoir. From April to Septem- ber in flood season, the water environmental capacity is relatively large, and both the COD and NH3-N receiving capacity account for 58% of the whole year. There is a positive correlation between the water environmental capacity and monthly water discharge.