Integrated Assessment of Improvement of the Water Environment in Lake Suwa and Arising Impact on Global Environment by Evaluating their Costs and Benefits

Abstract

Environmental load, such as CO₂, will increase with the enforcement of the measures to improve water environment. The objective of this study is the integrated assessment of such measures by evaluating the regional and global environmental impacts with costs and benefits. The construction of sewer pipe network and sediment dredging in Lake Suwa, Nagano prefecture was assessed as the case study. The benefit of improvement in water environment was estimated as 728 million [yen·year^-1] by analyzing the results of the questionnaire applied contingent valuation method on basin of Lake Suwa. On the other hand, the damage cost of global warming by additional CO₂ emission was estimated to be 1 to 23 million [yen·year^-1] by carrying out life cycle inventory analysis of the measures. Environmental benefit of improvement of water environment was much higher than the damage in global environment.