贵州南明河水环境综合整治与水质模拟

Comprehensive improvement and water quality simulation of Nanming River in Guizhou Province

以贵州南明河为例,对城市河道水环境综合治理全流程进行了系统的定量综合分析.污染识别结果表明,外源污染是造成南明河污染的关键原因,其对南明河COD、氨氮和TP等污染物的贡献分别达68%、95%和77%;COD和氨氮是南明河的主要入河污染物(80%和60%的入河外源来水中COD和氨氮水平劣于地表V类水).采取截污纳管、污水处理及河底清淤等针对性的治理措施,可共削减南明河COD、氨氮和TP污染负荷41414.6、874.2和218.0 t·a^(-1);通过生态建设恢复河道自净能力并运行半年后,南明河整治段劣V类河道长度占比从整治前的51.0%下降至17.4%,达到地表水V类的水质段由原来的10.1%提高至24.3%.建立MIKE模型预测综合整治措施3期工程全部完工时南明河水质运营情况发现,南明河下游水质断面能稳定达到IV类水体,但在枯水期仍可能存在部分河段TP和氨氮超标的情况.通过从上游水库(红枫湖,II类水)进行生态补水以保障南明河干流城区段稳定达标IV类水体,在考虑模拟误差且保证率高于90%的情况下,枯水期最高补水量应达到3.47m^3·s^(-1).

This study investigated the comprehensive improvement process of Nanming River in southwest China quantitatively and systematically. It was found that the exogenous pollutions,instead of endogenous ones,were the major source of contaminants entering the river. The contribution of exogenous pollutions to the COD,ammonia and total phosphorus（ TP） that entered the river reached 68%,95% and 77%,respectively. The COD and ammonia were the dominant contaminants（ 80% and 60% of the exogenous wastewater streams possessed higher COD and ammonia,respectively,than Grade V water）. Particular measures were taken including sewage collection system,wastewater treatment plants and dredging efforts,with total COD,ammonia and TP of Nanming River reduced by 41414.6,874.2 and 218.0 t·a-1,respectively. Besides,ecological constructions helped recover the self-cleaning capacity. As a result,half a year later,the percentage of Grade V＋ water from the whole river decreased from 51.0% to 17.4%,while the proportion that satisfied the standard of Grade V increased from 10.1% to 24.3%. A simulation model was established using MIKE software to predict the water quality upon completion of Stages I ~ III of the comprehensive improvement projects. The results showed that the downstream water quality of the Nanming River could constantly be maintained at Grade IV level,although there might still be part of the river processing excess TP and ammonia relative to Grade IV during dry period. Water transfer from the upstream reservoir（ Hongfeng Lake,Grade II） could be considered to supplement the water for the urban section of main stream to ensure a constant satisfaction to Grade IV standard. To this end,the supplementary flow rate should be up to 3.47 m3·s-1 when model errors were taken into account with 90% guarantee rate.