Societal Preference Valuation of Water Environment for Co-benefits Approach of Biogas CDM Project

Abstract

Two factories in Ayutthaya and Krabi provinces in Thailand were chosen to develop an evaluation model to estimate the co-benefits of Clean Development Mechanism (CDM) for water environment improvement from biogas recovering projects. The valuation framework included the analysis of spatial scales of water quality perception to examine how stakeholders at different institutional scales attach values to sites. A questionnaire survey was used to elicit willingness-to-pay (WTP) with closed-end double-bounded questions for one-step improvement in river water quality from status quo. Water quality perception showed 79% of respondents agreed to pay with WTP varied across respondent groups. At the provincial scale, households in Ayutthaya had a higher WTP with an average of 77.9 baht/household/month, whereas, households at the national scale had a higher WTP of 75.3 baht/household/month for Krabi. With the censored regression model from the general perspective of water quality services, the most important endogenous variables associated with the WTP were household income and household members. Nevertheless, at the national scale, education and attitude factors became more important because of acknowledged public benefits in terms of land use in the provinces. Hence, it is proposed that the importance of spatial scale in water quality perception be measured and compared separately for co-benefits assessment.