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Products: Sustainability

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Efficient Management of Coastal Marine Nutrient Loads with Multiple Sources of Abatement Instruments

Pollution management based on marginal abatement costs is optimal only if those abatement costs are specified correctly. Using the example of nitrogen pollution in groundwater, we show that the marginal abatement cost function for any given pollution source can be directly derived from a social-welfare maximization problem, wherein controls include both abatement instruments and inputs to pollution-generating production of a good or service. The solution to the optimization model reveals that abatement instruments for each source should be used in order of least marginal abatement cost, and the sources should in turn abate in order of least cost. The least-cost result remains optimal, even when the abatement target is exogenously determined.

Working Paper


Ordering Renewables: Groundwater, Recycling and Desalination

 

Optimal recycling of minerals can be thought of as an integral part of the theory of the mine. In this paper, we consider the role that wastewater recycling plays in the optimal extraction of groundwater, a renewable resource. We develop a two-sector dynamic optimization model to solve for the optimal trajectories of groundwater extraction and water recycling. For the case of spatially increasing recycling costs, recycled water serves as a supplemental resource in transition to the steady state. For constant unit recycling cost, recycled wastewater is eventually used as a sector-specific backstop for agricultural users, while desalination supplements household groundwater in the steady state. In both cases, recycling water increases welfare by shifting demand away from the aquifer, thus delaying implementation of costly desalination. The model provides guidance on when and how much to develop resource alternatives.

WORKING PAPER


Optimal Provision and Finance of Ecosystem Services: the Case of Watershed Conservation and Groundwater Management

Payments for ecosystem services should be informed by how both the providing-resource and the downstream resource are managed. We develop an integrated model that jointly optimizes conservation investment in a watershed that recharges a downstream aquifer and groundwater extraction from the aquifer. Volumetric user-fees to finance watershed investment induce inefficient water use, inasmuch as conservation projects actually lower the optimal price of groundwater. We propose a lump-sum conservation surcharge that preserves efficient incentives and fully finances conservation investment. Inasmuch as proper watershed management counteracts the negative effects of water scarcity, it also serves as adaptation to climate change. When recharge is declining, the excess burden of non-optimal watershed management increases.

working paper

 


Optimal and Sustainable Groundwater Extraction

With the specter of climate change, groundwater scarcity looms as an increasingly critical issue worldwide. Minimizing the adverse effects of scarcity requires optimal as well as sustainable patterns of groundwater management. We review the many sustainable paths for groundwater extraction from a coastal aquifer and show how to find the particular sustainable path that is optimal. In some cases the optimal path converges to the maximum sustainable yield. For sufficiently convex extraction costs, the extraction path converges to an internal steady state above the level of maximum sustainable yield. We describe the challenges facing groundwater managers faced with multiple aquifers, the prospect of using recycled water, and the interdependence with watershed management. The integrated water management thus described results in less water scarcity and higher total welfare gains from groundwater use. The framework also can be applied to climate- change specifications about the frequency, duration, and intensity of precipitation by comparing before and after optimal management. For the case of South Oahu in Hawaii, the prospect of climate change increases the gains of integrated groundwater management.

working paper


Optimal Management of a Hawaiian Coastal Aquifer with Near-Shore Marine Ecological Interactions

We optimize groundwater management in the presence of marine consequences of submarine groundwater discharge (SGD). Concern for marine biota increases the optimal steady-state head level of the aquifer. The model is discussed in general terms for any coastal groundwater resource where SGD has a positive impact on valuable near-shore resources. Our application focuses of the Kona Coast of Hawai’i, where SGD is being actively studied and where both near-shore ecology and groundwater resources are serious socio-political issues. To incorporate the consequences of water extraction on nearshore resources, we impose a safe minimum standard for the quantity of SGD. Efficient pumping rates fluctuate according to various growth requirements on the keystone marine algae and different assumptions regarding recharge rates. Desalination is required under average recharge conditions and a strict minimum standard, and under low recharge conditions regardless of minimum standards of growth.

working paper


An Economic Assessment of Biological Control for Miconia calvescens in Hawaii

Biocontrol, the introduction of organisms to control an unwanted species, has been cited as a powerful method to manage the invasive species Miconia calvescens in Hawaii. In addition to ecological advantages, biocontrol is often regarded as less costly than traditional methods despite the large initial investment. Currently, miconia in Hawaii is treated through aerial and manual operations, which cost over $1 million annually. Biocontrol for miconia in Hawaii began in 1997 and the search for more agents continues today. Although biocontrol for miconia has already begun, prior to this study no assessment of its economic justifiability had been done. This research evaluates the present value of net benefits of miconia biocontrol in Hawaii. Cost data were gathered from scientists in charge of biocontrol programs. Benefits were defined as the cost-savings of current control methods. Two different biocontrol programs were modeled: control achieved by a single agent, and control achieved by a suite of agents. In addition, different dispersal rates and efficacies of biocontrol and two release dates were modeled. Because most costs of biocontrol are incurred before the release of a successful agent and the benefits are only realized post-release, each scenario was evaluated over a 50-year time horizon. The results indicate a positive present value of net benefits in all scenarios, ranging from $12.8 million to $36.1 million. Thus, biocontrol for miconia in Hawaii appears to be economically justifiable. This research should enable scientists, economists and policy makers to make informed decisions about the optimal management of Miconia calvescens in Hawaii.

working paper


Spatial Economic Analysis of Early Detection and Rapid Response Strategies for an Invasive Species

Economic impacts from invasive species, conveyed as expected damages to assets from invasion and expected costs of successful prevention and/or removal, may vary significantly across spatially differentiated landscapes. We develop a spatial-dynamic model for optimal early detection and rapid response (EDRR) policies, commonly exploited in the management of potential invaders around the world, and apply it to the case of the Brown treesnake (Boiga irregularis) in Oahu, Hawaii. EDRR consists of search activities beyond the ports of entry, where search (and potentially removal) efforts are targeted toward areas where credible evidence suggests the presence of an invader. EDRR costs are a spatially dependent variable related to the ease or difficulty of searching an area, while damages are assumed to be a population dependent variable. A myopic strategy in which search only occurs when and where current expected net returns are positive is attractive to managers, and, we find, significantly lowers present value losses (by $270m over 30 years). We find further that in the tradeoff between search costs and damages avoided, early and aggressive measures that search some high priority areas beyond points of entry even when current costs of search exceed current damages can save the island more ($295m over 30 years). Extensive or non-targeted search is not advised however.

working paper


Invasive Species Control over Space and Time: Miconia calvescens on Oahu, Hawaii

We use Geographical Information Systems (GIS) to map the current and future populations of an invasive species, Miconia calvescens, on the island of Oahu, Hawaii, and the potential damages to water quantity, water quality, endangered bird habitat, and native habitat housing endangered plants, snails, and insects. We develop a control cost function that includes locating and treating Miconia plants. Using optimal control theory, we find the spatially dependent optimal population levels of Miconia and the paths to these populations over time.

Published: Burnett, K. M., Kaiser, B. A., and Roumasset, J. A., 2007. Invasive Species Control over Space and Time: Miconia calvescens on Oahu, Hawaii. Journal of Agricultural and Applied Economics, 39 (October 2007), 125-132.

Working Paper version


Economic Impacts of E. Coqui frogs in Hawaii

Hawaii’s geographical isolation has resulted in the development of unique and fragile ecosystems in which the arrival of a new species may create dramatic changes in the ecology, and now the economy, of the islands. Successful establishment rates for new species before the arrival of humans in the early 1st millennium AD may have been as low as one new species every 10,000 years (Loope, 1997). Only one terrestrial mammal, a bat (now extinct), reached the island chain without human assistance. Many other suborders are unrepresented; for example, the islands have no native snakes or frogs.

working paper


Renewable resource management with stock externalities: Coastal aquifers and submarine groundwater discharge

This paper develops a hydrologic-ecologic-economic model of groundwater use. Particularly, we model coastal groundwater management and its effects on submarine groundwater discharge, nearshore marine water quality, and marine biota. We show that incorporating the external effects on nearshore resources increases the optimal sustainable steady-state head level. Numerical simulations are illustrated using data from the Kuki’o region on the island of Hawaii. Two different approaches for incorporating the nearshore resource are examined. Including algae’s market value in the objective function results in only slightly lower rates of extraction. When a minimum constraint is placed on the stock of the keystone species, however, greater conservation may be indicated. The constraint also results in non-monotonic paths of water extraction, head level, and water price in the optimal solution.

Published: Pongkijvorasin, S., Roumasset, J., Duarte, T. K., and Burnett, K., 2010. Renewable resource management with stock externalities: Coastal aquifers and submarine groundwater discharge. Resource and Energy Economics, 32 (3), 277-291.

 working paper version


Resource management for Sustainable Development of Island Economies

What is the role of resource management in sustaining competitiveness for island economies such as the Republic of the Philippines and Hawaii? We review the history of thought on sustainable resource management and sustainable development and then turn to the threats to sustainability from the resource curse and the parallel curse of paradise. We show how the resource curse undermines the pursuit of sustainability and describe innovations in governance that can transform the curse into a blessing.

working paper


Environmental Resources and Economic Growth

This chapter assesses the nature and degree of environmental degradation and resource depletion in China and their relationship to economic activity and envi- ronmental policies. We describe regulatory and other policies and consider their political economy determinants. Inasmuch as this objective can only be partially achieved, we hope to contribute to a research agenda for environmental and resource economics in China.

Book Chapter


Optimal Prevention and Control of Invasive Species: The Case of the Brown Treesnake

This dissertation examines the optimal management of a nuisance species that threatens but is not thought to be prevalent in an ecosystem. The three central chapters focus on integrated prevention and control of the Brown Treesnake (Boiga irregularis) in Hawaii.

dissertation


Learning-by-catching: Uncertain invasive-species populations and the value of information

This paper develops a model of invasive species control when the species’ population size is unknown. In the face of an uncertain population size, a resource manager’s species-control efforts provide two potential benefits: (1) a direct benefit of possibly reducing the population of invasive species, and (2) an indirect benefit of information acquisition (due to learning about the population size, which reduces uncertainty). We provide a methodology that takes into account both of these benefits, and show how optimal management decisions are altered in the presence of the indirect benefit of learning. We then apply this methodology to the case of controlling the Brown Treesnake (Boiga irregularis) on the island of Saipan. We find that the indirect benefit—the value of information to reduce uncertainty—is likely to be quite large.

Published: D'Evelyn, S. T., Tarui, N., Burnett, K. and Roumasset, J. A., 2008. Learning-by-catching: Uncertain invasive-species populations and the value of information.  Journal of Envrionmental Management, 89, 284-292.

working paper version


Models of Spatial and Intertemporal Invasive Species Management

Prepared for the NCEE Valuation for Environmental Policy: Ecological Benefits Conference April 23-24, 2007.

uhero project report


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