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The recent stated preference literature emphasises the importance of incentive compatible elicitation methods, which depend on respondent beliefs that payment can be collected if provision occurs. We investigate this condition in a randomised field experiment where stated choices are incentivised financially. The objective of the treatment was to make choices salient by making each decision financially relevant and to increase the respondents' beliefs that future payments will be enforced. Our results show that the treatment increases estimates of the marginal utility of income, with the effect being economically and statistically significant for low‐income respondents. We develop a stylised theoretical framework that allows us to quantify the bias that is implied by the observed differences between the treated and control groups. We find that failure to account for respondents' doubts about payment coercion in an otherwise well‐designed survey inflates the marginal willingness to pay among low‐income respondents by a factor of at least 1.72. [ABSTRACT FROM AUTHOR]

A multivariate GARCH model of natural resources is specified to capture the effects of time varying portfolio risk. A special feature of the model is the inclusion of realized volatility for natural resource assets that are available at multiple frequencies as well as being sensitive to sudden changes in climatic conditions. Natural resource portfolios under climate change are simulated from bootstrapping schemes as well as being derived from global climate model projections. Both approaches are applied to a multiasset water portfolio model consisting of reservoir inflows, rainwater harvesting, and desalinated water. The empirical results show that while reservoirs remain the dominant water asset, adaptation to climate change involves increased contributions from rainwater harvesting and more frequent use of desalinated water. It is estimated that climate change increases annual water supply costs by between 7% and 44% over a 20‐year forecast horizon. [ABSTRACT FROM AUTHOR]

Although water supply diversification has been proposed as a solution to dwindling water reserves, the optimal mix of natural and manufactured sources of water remains largely unexplored. We develop a dynamic portfolio model of water supply that hedges against the supply risks from all potential water sources, by taking into account the size of water reserves, uncertainties of water flows as well as differences in supply costs. The optimal portfolio shares for an existing water supply system are derived and compared with the observed contributions to total water stock, revealing unexploited hedging opportunities between various naturally occurring water sources as well as a general over-reliance on manufactured water. The optimal solution implies that future supply augmentations should target natural sources of water ahead of manufactured water. It is estimated that the optimization of the water supply portfolio for a medium-sized city results in annual cost-savings of up to $463 million. [ABSTRACT FROM AUTHOR]