Ecological Community Analysis for the Establishment of River Environmental Management Planning

For the river environmental management, it is important to consider both water quality and other environmental conditions affecting ecological communities. Ecological methods are effective to analyze and to evaluate river environment totally. Most previous studies of biological indicators, however, aimed at only the evaluation of water quality. Therefore, I propose a new methodology using ecological technique for analysis and evaluation of river environment. The method is as below: 1) Classification of study site using ecological data. Cluster analysis using Bray-Curtis similarity is recomended. 2) Finding of the major environmental factors affecting ecological communities. 3) Translation of the factors into some mappable variables such as landuse and geographycal classification. 4) Segmentation of the rivers using the mappable data. 5) Environmental evaluation using biological indicators. Note that each indicator has unique characteristics. For example, the indicators using diatoms indicate water quality, those using benthic invertebrates indicate both water quality and river bed conditions. To test the validity of the method proposed in this paper, the ecological data of diatom flora, benthic fauna and fish communities in the rivers in Tokyo Metropolis were analyzed. Based on the result of multivariate analysis of ecological data, the rivers were divided into eight section within which diatom flora and aquatic fauna were almost homogeneous. Each section was evaluated using four kind of biological indicators and some guidances to manage the environment were produced. It can be said that the use of ecological analysis is effective in planning river environmental management