基于灰色关联分析法的辽河保护区河流水生态健康评价

Assessment on river water ecological health based on grey relation analysis in Liaohe Conservation Area

灰色关联分析是一种高效的不确定性复杂系统评价方法,具有对数据要求低且计算量小,便于广泛应用的特点,适用于河流水生态健康评价。基于水生态健康内涵和辽河保护区河流实际情况,构建了由河流自然形态状况、水质状况、底质状况、水生生物及生态环境状况四大类共20个指标组成的河流水生态健康评价指标体系,采用层次分析法(AHP)确定权重,结合灰色关联分析法对辽河保护区水生态健康状况进行评价。结果表明:辽河保护区河流水生态健康状况总体为中等,其中自然形态状况灰色关联度为0.868 4,健康等级为中等;水质状况灰色关联度为0.691 2,健康等级为中等;底质状况灰色关联度为0.968 6,健康等级为优秀;水生生物及生态环境状况灰色关联度为0.750 4,健康等级为中等。20个指标中,河床稳定性、河道弯曲程度、化学需氧量、总磷浓度、鱼类多样性指数和着生藻类多样性指数的评价结果为中等,总氮浓度为病态。自2010年辽河保护区划定以来,其河流底质中重金属污染得到较大改善,但仍存在河床稳定性差、水质污染、鱼类多样性和着生藻类多样性指数较低等问题。

Grey relation analysis is an efficient method for evaluating uncertain complex systems.It has the advantages of low data requirement,small computation and wide application and is an appropriate method for river water ecological health evaluation.Based on the connotation of water ecological health and the actual situation of rivers in Liaohe Conservation Area,a river water ecological health evaluation index system composed of 4 criterion layers and 20 indicator layers,including natural morphology,water quality,sediment,aquatic organisms and ecological environment,was constructed.Analytic hierarchy process(AHP)was used to determine the weight of criterion layer and,combined with grey relation analysis,to evaluate the water ecological health status of Liaohe Conservation Area.The results showed that the comprehensive health status of water ecology in Liaohe Conservation Area was medium,the grey relation degree of natural morphology was 0.8684,and the health status was medium.The grey relation degree of water quality was 0.6912,and the health condition was moderate.The grey relation degree of sediment was 0.9686,and the health condition was excellent.The grey relation degree of aquatic organisms and ecological environment was 0.7504,and the health status was also moderate.Among the 20 evaluation indexes,river bed stability,river bend degree,chemical oxygen demand,total phosphorus concentration,fish diversity index and algal diversity index were of medium health grade,while total nitrogen concentration was pathological.Since the establishment of the Liaohe Conservation Area in 2010,heavy metals pollution in the sediments of the river has been greatly improved,but there were still problems such as poor riverbed stability,water quality index pollution,low fish diversity and low algal diversity index.