Relating objective and subjective measures of water quality in the travel cost method: An application to the Peconic Estuary System.

摘要

This study models and estimates the changes in recreational beach use and values that are expected to result from improvements in water quality measurements at various monitoring stations in the Peconic Estuary System (PES). The linkage between improved water quality measurements and changes in recreational beach use and values is created by a two-step modeling process. In the first step, an ordered logit model quantifies the relationship between objective water quality measurements at water quality monitoring stations throughout the PES and the individual's qualitative ranking of water quality (poor, fair, good, and excellent).;The predicted probability results of the ordered logit model are used as explanatory variables in a count data model (Poisson) of recreational beach use. The count data model is structured as a travel cost model that estimates participation and consumer surplus. The participation and consumer surplus impacts of water quality management actions are illustrated by comparing model results with and without assumed water quality changes. Changes in actual water quality measurements at water quality sampling stations throughout the PES were found to affect the output probabilities of the ordered logit model. For example, improving water quality measurements at sampling stations near a local beach increases the probability that water quality at that beach would be ranked good or excellent. These affected probabilities are applied to the count data model, which estimates the ex post levels of use and consumer surplus. The method developed in this research allows for the estimation and comparison of the benefits of heterogeneous local water quality improvements. Increases in aggregate number of trips and aggregate consumer surplus for hypothetical 10% and 20% improvements in each of four objective water quality measures are calculated for each of the five water bodies of the PES and for the entire system.