Economical evaluation of environment around the Nagara River by using contingent valuation method
（CVM）Abstract
Nagara River was abundant in natural resources, because it didn't have any dams in the main river. But, since the estuary dam had been constructed at the mouth of the river in 1995, it has been obvious that the dam has caused serious damages to the ecosystem. For example, water quality has been getting worse, the number of fishes, particular sweet fish and Satukimas, are on the decrease, and the shellfishes were completely destroyed at the upper of the estuary dam and are remarkably on the decrease at the lower of the dam. The ecosystem couldn’t be improved perfectly without removing the dam. The purpose of this study is to estimate the economic value of Nagara River ecosystem by Contingent Valuation (CV).
In also Japan, CV is regarded as the valid method for estimating the non-use value of ecosystem, such as option value and existence value, at the present time. We conducted a questionnaire survey of the basin of Nagara River, Nagoya and Tokyo. The main query of this questionnaire is, “If Nagara River ecosystem were improved by removing the dam, could you pay **** yen by tax for improving Nagara River? “ We asked each respondent with double-bounded dichotomous choice method. If the first response is yes, the second bid is greater than the first bid. While, if the first response is no, the second bid is smaller. We mailed a questionnaire to 5000 households in October 2000, and we got an answer from each 1132 household. We estimated the economic value of Nagara River ecosystem at 336,153,805,000 yen/year by survival analysis. The value throughout was estimated at about 8 trillion yen. By showing the economic value of Nagara River ecosystem, people could reconsider Nagara River from a new viewpoint, and realize the importance of the Nagara River ecosystem.