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Ensaios em economia dos recursos naturais
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This dissertation is composed of four papers in natural resource economics. The first three study different aspects of groundwater quantity-quality management, whereas the fourth is an essay on the effects of technological progress in non-renewable resource extraction.
The value of water as a resource depends as much on the quantity available as on its quality. Economic literature has covered both aspects extensively but independently: there are papers that evaluate different schemes of dynamic aquifer management, considering that pumping costs vary with stock but ignoring water quality. On the other hand, there are papers that consider contamination problems caused by specific
pollutants.
The first chapter of the dissertation brings quality considerations into a deterministic model of resource management. Since groundwater is typically exploited as a common property resource, externalities are pervasive. It would be natural to suppose that optimal management yields a larger aquifer of better quality than what private agents achieve. The paper shows that this is not necessarily true: intervention may lower quantity while improving quality or vice-versa. It is also shown that, in spite of the external costs associated with contaminant discharges, the stationary level of discharges chosen by the users of the groundwater may be higher or lower than the efficient one, as long as steady-state water quality is higher in the efficient solution.
Different equations for quality evolution are proposed and each one's effect on results is assessed.
The second chapter presents two alternative models for joint quality -quantity management: water productivity can depend on water quality, but even if it does not quality may still enter the problem through legal minimum quality requirements. Optimal taxes are derived, and shown to be different from those in existing quantity-only or quality-only models, which can be seen as particular cases of the joint model. Policy
implications of joint quantity-quality management are discussed and implementation problems are briefly discussed. An illustration is also provided.
Under simple assumptions, deterministic models of conjunctive surface and groundwater management aren't much more complicated than typical groundwater-only management models. However, when water quality problems exist, the fact that there are two alternative sources of water gains a new significance, as there is no guarantee that they will be of comparable quality. Thus the benefit from using one unit of surface water may not be the same as that of one unit of groundwater. The third chapter analyses the implications of considering a conjunctive ground and surface water system where water quality varies according to source, with and without uncertainty in hydrological parameters.
Finally, the last paper in the dissertation provides a comparative dynamics analysis of technological change. Non-renewable resource scarcity has been a traditional concern when designing optimal growth models. Technological change has played an important role in those models, since it mitigates the depletion effect on extraction paths over time. This chapter examines the impact of different kinds of technological change in the context of a competitive resource industry. Two cases are considered.
In the first case, prices are assumed to be exogenous, while in the second demand is introduced. Based on the variational differential analysis, previous results in the literature concerning the evolution of scarcity measures are re-examined for simultaneous parameter changes (technology and price) and alternative boundary conditions.
Testable conditions are derived which might be of empirical interest.