基于模糊综合评价与灰色关联分析的河流自然性评价

Naturalness evaluation of rivers based on the fuzzy comprehensive evaluation and the grey correlation analysis

【目的】永定河是海河水系五大河之一,其自然性状况对北京地区居民饮水安全和海河流域水环境均有重要影响,基于“近自然”理念的河流自然性评价是保护和恢复河流自然状态的基础。【方法】以永定河北京山峡段为研究对象,从河流的水文要素、断面形态、水体理化性质、河岸带状况和社会生态价值5个方面,选取了25个定性、定量指标,构建了河流自然性评价指标体系。运用层次分析法与熵权法结合的组合赋权方式计算各指标在评价体系中的权重。用模糊综合评价法和灰色关联分析法分别对河流进行自然性评价和自然等级判定。【结果】模糊综合评价法和灰色关联分析法的评价结果总体一致,划分的21个调查河段中处于自然状态、近自然状态、退化状态和人工状态的河段分别占总河长的14.29%、28.57%、46.62%和9.52%,长度分别约为7.5、15.0、25.0和5.0 km。【结论】总体上,调查河段大部分处于退化状态,但仍具有潜在的近自然修复能力。采用的模糊综合评价法与灰色关联分析法均是可行的河流自然性评价方法。

[Objective]To restore and better protect the naturalness of Yongding River,one of the five major rivers in Haihe River Basin,the current study is aimed at the naturalness evaluation of it based on the close-tonature concept,which is of grate significance of the drinking water safety of residents in Beijing and the water environment of Haihe River Basin.[Method]Taking the Beijing gorge section of Yongding River as the study subject,the evaluation index system of river naturalness was constructed with 25 qualitative and quantitative indexes selected from five aspects,namely,hydrological elements,cross-sectional configuration,physical and chemical properties of water body,riparian zone conditions and social ecological value of river.Then,the weight of each index in the evaluation system was calculated with the weighting method of analytic hierarchy process intergrated with the entropy weight method before the naturalness of the river is evaluated and the natural grade is determined employing the fuzzy comprehensive evaluation method and the grey correlation analysis respectively.[Result]The naturalness of the river evaluated employing fuzzy comprehensive evaluation method is generally consistent with that using the grey correlation analysis,and among the 21 river segments,the natural,near-natural,degraded and artificial river segments accounted for 14.29%,28.57%,46.62%and 9.52%of the total river length,respectively,and the length is about 7.5,15.0,25.0 and 5.0 km.[Conclusion]In general,most of the investigated river segments are being degraded,but they all still display potential in restoring the naturalness and the fuzzy comprehensive evaluation method and grey correlation analysis are both feasible methods for river naturalness evaluation.