基于层次-灰色关联分析的河流自然性评价——以潮河为例

Assessment of river naturalness based on grey relational analysis and analytic hierarchy process:A case study of Chaohe River

基于"近自然"理念的河流自然性评价是对河流生态系统修复与保护的重要理论基础。以潮河古北口大桥至辛庄桥河段为例,依据潮河的自然属性和社会服务属性,在划分河段的基础上,构建了包含水文、形态、水质、河岸带功能和景观娱乐功能5方面、24个指标组成的河流自然性评价体系。参照"河溪近自然评价"方法获取评价指标,并根据各指标的评判标准依照自然状态、近自然状态、退化状态和人工状态进行归一化处理。运用层次分析法计算各指标在评价体系中所占权重。通过点到区间距离的灰色关联度计算方式进行自然等级判定。结果表明,调查河段由于受到自然演变和人为影响,处于人工状态的河段为2段,处于退化状态的河段为9段,处于近自然状态的河段为4段,处于自然状态的河段为1段,其中,退化和近自然状态的河段分别占调查河段全长的60%和31%,长度约为12.58和6.6 km。总体上,调查河段大部分处于退化状态,但仍具备进行近自然修复的潜在条件。采用层次-灰色关联分析的河流自然性评价方法计算简单,评价体系系统性强,各项指标对评价结果的影响明显。

[Background] Riparian ecosystem functions play important roles in human society and economic development. An objective and systematic assessment method can provide theoretical support for the restoration and protection of riparian ecosystem. In this paper,the Chaohe River（ river reach from Gubeikou Bridge to Xinzhuang Bridge） was taken as a case to study the method of river naturalness assessment based on the concept of ＂near-natural＂. [Methods]According to the natural quality and social service attributes of the Chaohe River,the river was divided into different sections. The 24 indicators were contained in the river naturalness assessment system,which involved 5 aspects including hydrological elements,river form,physical and chemical properties of water quality,riparian zone status,and the furaction of landscape and recreation. The investigation method of assessment indicators has been studied by reference to the ＂near-natural assessment system of stream ＂. According to the judgment criteria of each indicator,the normalization processing was carried on according to the natural state,the near natural state,the degraded state and the artificial state. The weight of each indicator in the assessment system was calculated by the Analytic Hierarchy Process（ AHP）. Taken the measured value of the index as the reference series,referring to the criterion as the comparison sequence,the gray correlation degree was calculated by the point to range distance. The maximum degree of relevance covresponding to the natural level was the final evaluation result. [Results]The assessment results indicated that in the light of natural evolution and human activity interference,there were two river sections in artificial state,nine river sections in degraded state,four river sections in near natural state,and one section in natural state. On the basis of this assessment results,1. 2 km of the river sections were in artificial state,12. 58 km of the river sections were in degradation state,6. 6 km of the river sections were in near-natural state and 0. 62 km of the river sections were in natural state which were about 6%,60%,31% and 3% of total length,respectively. [Conclusions]In general,although most of the survey sections of Chaohe River were in the state of degradation,there were still potential conditions for near natural restoration in the long run. It may promote river to a higher natural level to complete the river restoration based on river ecosystem assessment results and taking advantage of combination of natural ways and artificial management. Furthermore,evaluation index system has a high systematicness,the calculation was simplified and the indicators have an obvious impact on the result by the method of natural assessment of rivers based on AHP and Grey Relational Analysis（ GRA）.