Abstract
There are five evaluation axes for the "soundness indicators of water environment". However, the levels of importance of each of these axes or individual indicators, which an observer considers, are not the same. In consideration of an investigator's subjectivity, the analytic hierarchy process (AHP) technique is proposed as a method of evaluating a water environment synthetically. The structure of subjective judgment, which serves as a backdrop to an investigator's judgment, is analyzed. First, the same subject performs water environmental research at three points of a case river and clarifies the features of each water environment. Subsequently, a hierarchical evaluation factor structure of the soundness index is built. By applying the AHP technique, the result well described subjectivity of the observer, which showed the different tendency from typical method. It is considered that the AHP technique is an effective method of understanding an investigator's feeling explicitly as well as the water environment completely.
