Abstract:

In order to understand the water quality status, changing trend and main characteristics of lakes and reservoirs in Guangdong Province, single factor evaluation method, comprehensive pollution index evaluation method, comprehensive nutrient status index method and the improved entropy weight method, TOPSIS model, were used to analyze the water quality monitoring results from 2018 to 2022. The results were that: 1) The water quality of all 38 key lakes and reservoirs in 2022 reached the water function target, 6, 25 and 7 lakes and reservoirs reached the Class I, Class II and Class III standards, respectively. The comprehensive pollution index of the lakes and reservoirs ranged from 0.06‒0.22, which indicated that all evaluation results reached good or above. The comprehensive nutritional status index ranged from 23.81‒53.42, and three lakes of Xinghu Lake, Huizhou West Lake and Hedi Reservoir were mildly eutrophic and had the risk of water bloom. 2) The evaluation results of the water quality of the lakes and reservoirs by the improved TOPSIS model showed that the water quality was fine. The evaluation results of Sanzhoutian Reservoir, Fengmulang Reservoir, Jingxin Reservoir and Chiao reservoir were 0.851, 0.828, 0.824 and 0.814, respectively, indicating the highest water quality. The ranking of the evaluation results of Xinxihe Reservoir, Cangcun Reservoir, Liuxihe Reservoir and Chisha reservoir were significantly different from the comprehensive pollution index, which suggested that they had environmental risks of heavy metals. The evaluation results of Hexi Reservoir, Xiuquan Reservoir and Hedi Reservoir were relatively low. 3) From the analysis of lake and reservoir types, the water quality of small reservoirs is the best, followed by medium-sized reservoirs, large reservoirs and lakes. In 2022, the overall water quality of the lakes and reservoirs did not change significantly. From the perspective of each season during the year, the water quality in spring was the best, while fluctuated greatly in summer, and the water quality was the worst, but the water quality improved in autumn. From the trend of inter-annual variation, the water quality of lake and reservoir basically improved year by year. From the perspective of regional location, the water quality of the lake and reservoir in Pearl River Delta region is the best. Through the improved TOPSIS model, the water quality of 38 key lakes and reservoirs in Guangdong Province was comprehensively analyzed, and the water quality characteristics were analyzed, which provided a successful practical basis for large-scale and multi-object scientific water quality comprehensive analysis technology, and also provided technical support for lake and reservoir water quality management and risk early warning.

Key words: TOPSIS model, entropy weight method, Key Lakes and Reservoirs in Guangdong Province, water quality characteristics, comprehensive pollution index, vegetative state

摘要：

为了掌握广东省湖库的水质状况、变化趋势及其主要特征，采用单因子评价法、综合污染指数评价法、综合营养状态指数法和熵权法改进的TOPSIS模型对2018－2022年湖库水质监测结果进行分析。结果表明，1）广东省38个重点湖库2022年水质全部达到水功能目标，达到Ⅰ类、Ⅱ类、Ⅲ类标准的湖库分别有6个、25个和7个；综合污染指数范围在0.06－0.22之间，评价结果全部达到良好及以上；综合营养状态指数范围为23.81－53.42，星湖、惠州西湖和鹤地水库3个湖库为轻度富营养，存在水华风险。2）改进的TOPSIS模型评价结果表明，湖库水质优良，其中，三洲田水库、枫木浪水库、径心水库和赤坳水库的评价结果分别为0.851、0.828、0.824和0.814，水质最优；新西河水库、苍村水库、流溪河水库和赤沙水库评价结果排名与综合污染指数相差较大，重金属存在一定的环境风险；河溪水库、秀全水库和鹤地水库评价结果排名相对较低。3）从湖库类型分析，小型水库水质最好，依次是中型水库、大型水库和湖泊；2022年湖库水质总体变化不大，从年内各季节看，春季水质最好，夏季水质波动较大，水质最差，秋季有所转好；从年际变化趋势看，湖库水质基本逐年好转。从区域位置看，珠三角地区湖库水质最好。通过改进的TOPSIS模型对广东省38个重点湖库水质进行综合分析，解析水质特征，为大范围多对象科学水质综合分析技术提供了成功的实践依据，为湖库水质治理和风险预警提供技术支撑。

关键词: TOPSIS模型, 熵权法, 广东省省重点湖库, 水质特征, 综合污染指数, 营养状态