模糊数学在丹江口水库富营养化评价中的应用

丹江口水库是南水北调中线工程水源地,其水质安全将直接影响调水工程的成败。基于2013年6月的水质监测结果,通过对水质指标的聚类,将丹江口水库划分子库区,并尝试使用模糊数学方法进行水质富营养化评价。结果表明,丹江口库区可分为6个子库区,各库区在透明度、溶解氧、浊度、高锰酸盐指数、总磷、硝酸盐氮和叶绿素a等理化指标均有显著差异;富营养化评价显示,库区总体营养状态级别为中营养。其中,坝前区域(库区Ⅰ)和丹库主体部分(库区Ⅵ)营养状态级别为贫营养,汉库原河道区(库区Ⅱ)为中营养,汉江入库口(库区Ⅲ)、汉库最大库湾(库区Ⅳ)、丹江入库口(库区Ⅴ)为轻度富营养。模糊综合评价法较好反映出水质的模糊性、连续性,使评价结果更加准确可靠。

Application of Fuzzy Mathematics for Evaluation of Eutrophication in Danjiangkou Reservoir

Danjiangkou Reservoir is the water source for the middle route of South-to-North Water Diversion Project, and therefore its water quality could directly influence the success of the project. Based on the result of water quality monitoring in June 2013, Danjiangkou Reservoir was divided into sub-reservoirs through hierarchical cluster analysis on water quality indexes, meanwhile, fuzzy mathematics was also adopted to evaluate the eutrophication of water quality. It was revealed that the six sub-reservoirs of Danjiangkou Reservoir differed significantly in terms of their physical and chemical indexes, such as transparency, dissolved oxygen, turbidity, permanganate index, total phosphorus, nitrate nitrogen, chlorophyll-a, etc.; according to the evaluation of eutrophication, the general nutritional status level of the reservoir is mesotrophic, thereinto, the front area of dam (Reservoir Area I) and the main body of Dan Reservoir (Reservoir Area VI) are oligotrophic; the original river course area of Han Reservoir (Reservoir Area II) is mesotrophic; the entrance of reservoir for Han River (Reservoir Area III), the biggest cove of Han Reservoir (Reservoir Area IV) and the entrance for Dan River (Reservoir V) are mild eutrophic. The fuzziness and continuity of water quality could be relatively clear revealed with the fuzzy comprehensive evaluation method, which improves the preciseness and reliability of evaluation result.