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Products: Project Environment

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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


KITV Project Economy: APEC Economic Impact

UHERO Research Fellow and Director of the EGGS program, Dr. Denise Konan discusses the economic impact of the APEC conference.

watch


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


Greenhouse Gas Emissions in Hawaii: Household and Visitor Analysis

This paper focuses on petroleum use and greenhouse gas emissions associated with economic activities in Hawai‘i. Data on economic activity, petroleum consumption by type (gasoline, diesel, aviation fuel, residual, propane), and emissions factors are compiled and analyzed. In the baseline year 1997, emissions are estimated to total approximately 23.2 million metric tons of carbon, 181 thousand metric tons of nitrous oxide, and 31 thousand metric tons of methane in terms of carbon-equivalent global warming potential over a 100-year horizon. Air transportation, electricity, and other transportation are the key economic activity responsible for GHG emissions associated with fossil fuel use. More than 22 percent of total emissions are attributed to visitor expenditures. On a per person per annum basis, emission rates generated by visitor demand are estimated to be higher than that of residents by a factor of 4.3 for carbon, 3.2 for methane, and 4.8 for nitrous oxide.

The full publication can be found at: http://www.sciencedirect.com/science/article/pii/S0140988309001133 


Analysis of Introduction of Plug-in Electric Hybrid Vehicles to Honolulu

The primary aim of this study is to understand the benefits and barriers which might be associated with the introduction of PHEV technology to Hawaii. This analysis illustrates that PHEV’s represent a much larger and more pervasive strategic opportunity than is generally appreciated in the State. Specific interests that guided our research were:

  • To estimate the impacts which relatively modest PHEV penetration rates might have on Hawaii’s GHG emission and fuel substitution goals.
  • To determine whether PHEV’s could be introduced to Hawaii without triggering major generating capacity additions.
  • To consider whether PHEV’s might play a role in optimizing the use of renewable wind resources that might otherwise be un-usable.
  • To assess the role of PHEV’s in the Hawaii’s attempt to control GHG emissions.

UHERO project report


Targeting Hawaii Greenhouse Gas Emissions Reductions: Emission Forecasts and Their Implications for Act 234

Act 234 calls for the state of Hawai‘i to return its greenhouse gas (GHG) emissions to 1990 levels by 2020. Under a business as usual environment, we forecast Hawai’i’s 2020 emissions to be between 18 and 34 percent above 1990 levels. Since transportation and electricity account for about 75 percent of Hawai’i’s GHG emissions, most likely a large share of the reductions will need to come from these sectors for Hawai’i’ to comply with Act 234.

Uhero project report


The Value of a Wave: An Analysis of the Mavericks Region Half Moon Bay, California

This study was commissioned by the Save the Waves Coalition to determine the value of the Mavericks surf area to the local community and beyond. 

working paper


Energy and Greenhouse Gas Solutions: Hawai‘i Greenhouse Gas Emissions Profile 1990 and 2005

In an effort to effect national and global climate change policy to address the increase in greenhouse gas emissions, the Hawai'i legislature passed the Global Warming Solutions Act of 2007, Act 234. Act 234 calls for Hawai'i to return its greenhouse gas (GHG) emissions to 1990 levels by 2020. Here we report an inventory of emissions for the state for 1990 and 2005, and forecast emissions growth out to 2020.

Uhero project report


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


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