三峡水库入库污染负荷研究（Ⅱ）——蓄水后污染负荷预测

在文献\1\]基础上，预测三峡水库2010年和2015年的入库污染负荷。采用包络线法预测排污得到有效控制的低负荷水平（最佳状态），排污继续恶化到一定限度的高负荷水平（最坏状态），以及按正常排污介于高、低负荷水平之间的中负荷水平（一般状态）。在预测入库污染负荷时，把长江、嘉陵江、乌江进入的背景水质污染负荷分为天然背景负荷和上游贡献负荷，天然背景负荷保持不变，上游贡献负荷根据上游水污染控制规划按高、中、低负荷水平预测。预测表明，库区内的污染负荷占入库总污染负荷的比例较小。中负荷水平下，库区污染源占入库总负荷的比例为8.50%～22.93％。污染负荷主要来自长江、嘉陵江、乌江上游的贡献和天然背景负荷。在低、中、高三种负荷水平下，扣除天然背景值时，2010年低负荷水平时BOD5库区负荷占28.8％、中负荷占32.5％、高负荷占35.04％。总磷出现反常，库区的总磷的污染负荷在低负荷水平下，所占入库负荷的比例高于中负荷水平、但小于高负荷水平。2010年、2015年库区的主要污染物质和污染负荷排放分布与现状（1998年）基本相同。主要排污区域为重庆主城区，2010年预测重庆主城区CODCr负荷占库区总负荷的比例，高、中、低负荷水平分别为：39.6%、36.2％、21.6％，低负荷比高负荷降低18％。库区的主要污染源为农业面源，2010年库区农业面源中CODCr负荷占总负荷的比例在高、中、低负荷水平下分别为：38.9%、47.5％、70.4％。同时，随着库区社会经济发展，污染负荷有逐步增大的趋势，到2015年所有污染物及负荷水平，均大于2010年和1998年。

STUDY ON THE POLLUTANT LOADS INTO THREE GORGES RESERVOIR ( Ⅱ ) --POLLUTANT LOAD PREDICTIONS AFTER IMPOUNDMENT

This paper predicts the pollutant loads into the Three Gorges Reservoir after impoundment in 2010 and 2015 based on reference paper\.The authors employed enveloping-line method to make three load levels: the low level,corresponding to the good condition,in which the pollution is controlled effectually;the high level,corresponding to the worst condition,in which the pollutant loads discharge get to worsen in a certain limit continuously;and the middle level,corresponding to the normal condition between the high and the low level.In the prediction,the background load from the Yangtze River,the Jialing River and the Wujiang River has been divided into two parts: the natural background load and the upstream contribution load.The natural background pollutant load kept constant and the upstream contribution load had high level,middle level and low level according to water pollution control planning of the upper reaches.The prediction results showed that the pollutant loads discharging to the reservoir directly occupy a low proportion of the total loads into the Three Gorges Reservoir.At middle load level,the pollutant loads from reservoir area occupy a proportion from 8.50% to 22.93% of the total loads.The main source comes from the background load,namely natural background load and upstream contribution load from the upper reaches of the Yangtze River,the Jialing River and the Wujiang River.At low,middle and high load levels,ignoring the natural background load,the reservoir area source BOD_5 load occupies 28.8%,32.5% and 35.04% of the total loads respectively in 2010.But the total phosphorus(TP) load shows some abnormality;the TP load at low load level is higher than that at middle load level,but lower than that at high load level.The main pollutant and distribution of the pollutant loads in 2010 and 2015 are similar to that in 1998.The main discharging district is the urban district of Chongqing City,the COD_Cr loads discharging at the high,middle and low levels are 39.6%,36.2% and 21.6% respectively in 2010;and at low load level,the COD_Cr load decreases about 18% compared to that at high load level.The main pollution source of the reservoir area is the agricultural non-point sources,the COD_Cr load of the agricultural non-point source from reservoir area occupies 38.9%,47.5% and 70.4% of total loads at high,middle and low load level respectively in 2010.The prediction results also showed that pollutant loads exhibit increasing trend with the social and economical development of the reservoir area,and the pollutant loads and the three load levels in 2015 will be larger than that in both 2010 and 1998.