A comparison of the values of water inflows into selected South African estuaries: The Heuningnes, Kleinmond, Klein, Palmiet, Cefane, Kwelera and Haga-Haga

Abstract

The functionality of estuaries is threatened by widespread and rapid transformation as a result of the significant reduction in the rate at which freshwater flows into them. We present standardized methods that combine freshwater abstraction and estuary functionality to estimate recreational values of freshwater inflow to households located in proximity to the seven selected South African estuaries while testing for the convergent validity of the contingent valuation method (CVM), zonal travel cost method (ZTCM) and the individual travel cost method (ITCM). Given that the dependent variable is the log transform, our dependent variable is not censored, so we use an OLS model for the regression, and model separately our zero values using a spike model. When running our regressions, we pool all observations from the seven estuaries and use dummy fixed effects for each estuary, and use interactions to model different effects of the covariates in each estuary. For travel costs analyses, we estimate truncated count data models of recreational demand taking into account the fact that the number of visitation trips taken is a non-negative integer. The CVM generated values per m3 of freshwater inflow into the estuary ranges from R0.0022 to R0.0546 whereas the ZTCM values ranges from R0.0035 to R0.0499, while the ITCM generated value per m3 of freshwater inflow is R0.003. The findings in this study are that some convergence of results is achieved.