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Economic Currents

Keep up to date with the latest UHERO news.

Cost-Effectiveness of Herbicide Ballistic Technology to Control Miconia in Hawaii

UHERO is working with Dr. James Leary (CTAHR) to assess cost effectiveness of Herbicide Ballistic Technology (HBT) operations to control invasive miconia (Miconia calvescens) plants before reaching maturity. Based on studies in Costa Rica, Tahiti and Australia, we can interpret spatial and temporal implications of management driven by miconia’s fecundity, dispersal, seed bank longevity and recruitment. We find that the dispersal kernel of miconia in the East Maui Watershed is closely matched to a similar probability density function developed from miconia naturalized in North Queensland, Australia (Fletcher and Westcott 2013). In this spatial model, 99% of recruitment was within 609 m with rare stochastic events (i.e., 1%) extending out to 1644 m. Based on these biological features, one autogamous, mature plant can impact up to 850 ha (i.e., 2100 acres) of forested watershed with hundreds to thousands of dispersed progeny germinating asynchronously over several decades (Fig. 1).

Figure 1. The dispersal kernel displays as a raster layer creating an 850-ha area calculation with corresponding probability density function (color shades).

Effective management is achieved when target mortality outpaces biological recruitment. Cacho et al. (2007) coined the term ‘‘mortality factor’’ described by the simple equation: m=Pd x Pk, where the probabilities of detection (Pd ) and kill (Pk)are equal determinants of the “mortality” product. Our current Pk is 0.98 for all HBT treatments. With this effective and reliable treatment technique, management outcomes largely depend on detection (Leary et al. 2013; Lodge et al. 2006). Koopman (1946) introduced the mathematical framework for estimating the probability of detection: Pd=1-e-c, where the probability of detection asymptotically approaches 1.0 with increasing coverage (Fig. 2). In operations, imperfect detection can be compensated by frequent interventions compounding coverage levels over time, but with obvious diminishing returns (Leary et al. 2014).

Figure 2. Probability of detection (blue) and the inverse for the equally important confirmation of no targets (orange). Note gray dash connotation of a theoretically “perfect” sensor, where coverage is equal to detection and confirmation.

The variable costs for HBT operations (e.g., flight time and projectiles) are driven by target density (Leary et al 2013, Leary et al. 2014). With that knowledge, we estimate the cost to manage the area (i.e., 850 ha) impacted by the dispersal of new progeny created by a mature plant. A new mature miconia with two panicles may produce ~300-400 progeny. With a single, incipient target being such a high risk, intensive efforts should be matched to comprehensively search the entire impact area over the several decades with a level probability of detection (and equal confirmation of no targets) of all progeny recruits. For instance, with 320 propagules dispersed, Pd would need to exceed 0.9968 with coverage at 5.77 s per 100 m2 pixel totaling ~136 hours of effort over the entire impact area over four decades (Fig. 3A). Any level of coverage less than that (including 99%) would be prone to missing a target that ultimately reaches maturity and newly replenishes the seed bank (Fig. 3B). Furthermore, an overwhelming majority of search effort would actually be dedicated to the confirmation of no targets, where, for instance 87% of effort is invested in looking for 1% of the targets dispersed out to the perimeter.

Figure 3. (A) Search effort (EFT; hours) over a 43-year period to match the level of coverage with the probability of detection from a random search effort. (B) is the reproduction of 2nd generation progeny by undetected targets of the 1st generation shown as Base 10 log scale.

Based on this model, we estimate accrual of future management costs ranging from $169,000-337,000 for every mature target detected, with the increase from the base cost dependent on increasing propagule loads and the static cost to treat each those individuals detected.

- James Leary, Kimberly Burnett and Christopher Wada



Cacho, O.J., Hester, S. and Spring, D., 2007. Applying search theory to determine the feasibility of eradicating an invasive population in natural environments. Australian Journal of Agricultural and Resource Economics, 51(4), pp.425-443. 

Fletcher C. S. and Westcott D. A.. 2013. Dispersal and the design of effective management strategies for plant invasions: matching scales for success. Ecological Applications 23:1881–1892. 

Koopman, B.O. (1946). Search and Screening. Operations Evaluations Group Report no. 56, Center for Naval Analyses, Alexandria, VA. 

Leary, J.J., Gooding, J., Chapman, J., Radford, A., Mahnken, B. and Cox, L.J., 2013. Calibration of an Herbicide Ballistic Technology (HBT) helicopter platform targeting Miconia calvescens in Hawaii. Invasive Plant Science and Management, 6(2), pp.292-303. 

Leary, J., Mahnken, B.V., Cox, L.J., Radford, A., Yanagida, J., Penniman, T., Duffy, D.C. and Gooding, J., 2014. Reducing nascent miconia (Miconia calvescens) patches with an accelerated intervention strategy utilizing herbicide ballistic technology.

Lodge, D.M., Williams, S., MacIsaac, H.J., Hayes, K.R., Leung, B., Reichard, S., Mack, R.N., Moyle, P.B., Smith, M., Andow, D.A. and Carlton, J.T., 2006. Biological invasions: recommendations for US policy and management. Ecological Applications, 16(6), pp.2035- 2054. 

Science and Community Engagement to Improve Water Management in Hawaii

‘Ike Wai (from the Hawaiian ‘ike, meaning knowledge, and wai, meaning water) is a five-year National Science Foundation project. The multidisciplinary research team from UH Manoa and Hilo will collect new geophysical and groundwater data, integrate these data into detailed groundwater models, and generate an improved understanding of subsurface water location, volume and flow paths. Data and outputs from ‘Ike Wai will be used to develop decision making tools to address challenges to fresh water scarcity from climate variability, increasing population demands, and water contamination.

UHERO Project Environment researchers will work with stakeholders to develop land-use scenarios, with a particular emphasis on potential areas for watershed restoration. Recharge values and restoration costs will be estimated for these scenarios and used as inputs to the groundwater model. Assumptions about development and population growth will be used to project consumption on the demand side, and the groundwater model will then allocate pumping spatially to minimize declines in water levels and deterioration in water quality due to seawater intrusion (SWI). Results from the pumping simulations can then be compared with current estimates of sustainable yield. We will also estimate the return on investment in watershed restoration for each of the scenarios.

The new field data and groundwater modeling efforts will help to improve current sustainable yield estimates. With recharge likely to change in the future due to climate change and land use decisions (e.g. watershed restoration), sustainable yield should also be variable. Although, current estimates of sustainable yield do not account for ecological and customary uses, several stakeholders have shown interest in developing a framework to do so. We will therefore look at how submarine groundwater discharge (SGD) along the coast varies with pumping and simulate the effects of different SGD constraints. We will also estimate the costs, in terms of restricting groundwater pumping, of enforcing those constraints. That is, we will: (1) compare projected groundwater consumption under each scenario to new sustainable yield estimates that account for both SWI and SGD, and (2) estimate the potential costs of maintaining pumping below sustainable yield.

Informing Water Policy in Hawaii with Transformative Interdisciplinary Research: UHERO’s Role in ʻIke Wai

UHERO's Project Environment will be leading the economic analysis for a new National Science Foundation project addressing critical gaps in the understanding of Hawaii’s fresh water supply that limit decision making, planning and crisis responses. ‘Ike Wai (from the Hawaiian ‘ike, (knowledge), and wai, (water) spans geophysics, microbiology, cyberinfrastructure, data modeling, indigenous knowledge and economics and connects university scientists to state and federal agencies and community groups.

Diversity in volcano age, eruption types, structural history, and hydrological features generate a complex subsurface water system that provides most of Hawaii’s potable water supply. While many hydrological studies have been carried out in Hawaii, relatively little is known about the exact structure of the many groundwater (GW) aquifers that are present throughout the state. Existing models are able to approximate the structure, but the accuracy of predicted water flows and sustainable yields for Hawaiian watersheds is limited by the availability of existing data, which is used to calibrate the models. Accordingly, ʻIke Wai will use new technology to measure the volume and interconnectivity of aquifers within Hawaiian volcanoes. Geophysical imaging will provide new high-resolution 3D maps of geologic structures. Real-time monitoring will support analysis of aquifer volume and hydraulic conductivity estimations. Flow and aquifer connectivity measurements will integrate three approaches: submarine GW Discharge (SGD) analysis, geochemistry and the innovative use of microbial diversity as a GW tracer.

Data and outputs from ʻIke Wai will provide decision-making tools to address challenges related to water availability and sustainability. Recent research on the West Hawaii coast has shown that we do not fully understand the size, flow rates, and boundaries of our groundwater aquifers. Without a clear understanding of how much water is available, we cannot properly plan future water use and management. There is currently significant debate over whether there is enough water to meet planned development while ensuring the biological and ecological integrity of surrounding nearshore habitats. ʻIke Wai will provide crucial geophysical data that will allow us to assess how much water is available to support both humans and nearshore environments.

Once we know the size, volume, and flow rates of groundwater aquifers, we can match these water supply estimates with current and projected demands for water. These demands come in the form of human demand — for domestic, commercial, agricultural, and municipal use — as well as biological and ecological demands — for example the dependency of nearshore organisms on freshwater discharge to the ocean, which is driven by the size and flow rate of up-gradient aquifers. The research from ʻIke Wai will help resource managers, policy makers, and the general public understand how scarce groundwater is in these areas, and how these resources should be priced, pumped, and managed to achieve the objectives that will be determined as part of our stakeholder engagement process. These objectives could be related to development, ecological integrity, and/or cultural integrity — we won’t know exactly what we are aiming for until we engage the stakeholders in our research.

The ʻIke Wai Initiative will give us a better sense of where the water is, how much is there, how much and where we can pump for what uses, and how we should best manage (price, restrict, require permits for, etc.) this resource. Stakeholder engagement and policy evaluation are also key components of the project, so we believe that the research results will not only be transformative from a scientific perspective but also useful for planning and management. Providing user friendly access to data and research results is an important objective of the project. Software engineers will work collaboratively with other members of the research team and stakeholders to create web and mobile applications for data dissemination, interaction and visualization.

For more information on the project, visit EPSCoR.

--Kimberly Burnett and Christopher Wada

Cost-Effectiveness of Controlling Invasive Miconia via Herbicide Ballistic Technology

Miconia calvescens is an invasive tree native to South and Central America that grows up to 50 feet with shallow root systems that promote erosion. The trees form thick monotypic stands, shading out native plants and threatening the watershed function of Hawaii’s forests. The quick growing miconia can mature in four years and produce 3 million seeds several times a year. It is thought that these seeds can remain viable for at least 18 years, and possibly much longer, before sprouting, potentially many more. Birds spread the tiny seeds when they eat the fruit, as do people when contaminated dirt or mud sticks to shoes, clothing, equipment, or vehicles.

Above: Herbicide is delivered via small purple pellet. Average treatment is 25 shots per plant.
Photo credit: Kimberly Burnett

Miconia was introduced to Maui in the early 1970s at a private nursery and botanical gardens near Hana, and now occurs in approximately 37,000 acres throughout East Maui. Maui Invasive Species Committee (MISC) has been managing Miconia for the last two decades, primarily through the use of ground crews and aerial treatment via long-line spray ball. Herbicide ballistic technology (HBT) was recently developed by Dr. James Leary (CTAHR, UH Manoa) as a way to complement these management strategies. The HBT platform delivers small amounts of herbicide into plant tissue from the air, allowing management in otherwise inaccessible locations. The herbicide is delivered via a small projectile fired from a device similar to a paintball gun.

Above: Getting a first-hand look at HBT operations in East Maui. L to R, Christopher Wada (UHERO), James Leary (CTAHR), Kimberly Burnett (UHERO).  Photo credit: Kimberly Burnett

UHERO’s Project Environment will be working with Dr. Leary to assess the cost-effectiveness of HBT technology relative to other management strategies. Key research questions include how to optimize frequency of surveillance, how to minimize the cost of reducing the population to a target level, where to focus HBT efforts (low density, isolated, high elevation/rainfall areas), and how to best combine HBT with other management strategies for maximum cost effectiveness.

--Kimberly Burnett and Christopher Wada


For more on the economics of Miconia from UHERO, see:

Economic impacts of non-indigenous species: Miconia and the Hawaiian economy

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

Economic lessons from control efforts for an invasive species: Miconia calvescens in Hawaii

Prevention, Eradication, and Containment of Invasive Species: Illustrations from Hawaii

Control of Invasive Species: Lessons from Miconia in Hawaii

An Economic Assessment of Biological Control for Miconia calvescens in Hawaii

Economic Analysis of the Water-Energy-Food Nexus: My Visiting Research Fellowship at the Research Institute for Humanity and Nature in Kyoto, Japan

Posted July 30, 2015 | Categories: Blog, Project Environment

Earlier this year I had the opportunity to work with an interdisciplinary team at the Research Institute of Humanity and Nature (RIHN) on a Visiting Research Fellowship examining “Human-Environmental Security in Asia-Pacific Ring of Fire: Water-Energy-Food Nexus." Our objective was to design research frameworks for conducting water-energy-food economic analyses for three study sites in Japan: Obama, Beppu, and Otsuchi.

Synergies and tradeoffs among water, energy use, and food production should be considered by stakeholders and decision-makers looking to maximize the benefit from each resource. Economics can help to identify these tradeoffs by quantifying the benefits and costs of water, energy, and food-related projects over long planning horizons, as well as by optimizing allocations of these resources over multiple uses. During my research fellowship we developed frameworks for economic analysis of the water-energy–food nexus using examples from three case studies in Japan: water allocation over multiple uses in Obama, renewable energy production in Beppu, and construction of a dike in Otsuchi. Each of these case studies involves choices that will affect inherent linkages between water, energy, and food in each system. Failing to recognize these tradeoffs can result in sub-optimal allocation of resources with respect to the economy, the ecology, society and culture.


Obama is a city on the Sea of Japan in Fukui Prefecture, where groundwater is an important resource for a variety of uses including domestic use, melting snow, and fishery production (via submarine groundwater discharge). Over-allocation of groundwater towards above ground uses has implications on the important fishery resource near shore. An economically efficient solution is characterized by groundwater utilization paths over time that maximize net benefits across uses, explicitly considering how using water for one purpose reduces the availability of water for other purposes. Aside from the direct tradeoff between groundwater and the fishery, a key variable in the model is the price of energy, which affects the costs of both groundwater pumping and alternative snow-melting techniques. The team developed a bioeconomic optimization model that can be used to solve for optimal allocation of groundwater to each of these three uses over time.

Beppu is a city in Oita Prefecture best known for its high concentration of natural hot springs (“onsen”). Onsen are an important economic and cultural resource, whose use has significant implications on the surrounding society and ecology. Interest in small-scale renewable energy production using hot water and steam from the onsen (“onsen hatsuden”) has increased in recent years, especially following the Tokohu earthquake/ tsunami/ nuclear meltdown disaster of 2011. There are two primary types of onsen hatsuden being developed in Beppu: binary systems which are more productive but generate larger social and ecological damages, and the smaller scale yukemuri hatsuden which have a much lower production capacity but are less harmful to the surrounding ecosystem and society. We designed an economic approach to comparing the benefits and costs of each system.

Otsuchi is a small town in Iwate Prefecture in northern Honshu, one of the most impacted following the Tohoku disaster of 2011. Estimates of total economic losses from Tohoku range from $50-$210 billion USD. The research team developed an economic approach to assessing the benefits and costs of a government-financed dike being constructed with the intention of preventing similar losses following a natural disaster in the future. Benefits include the reduced risk of future losses, while costs include not only dike construction, operation and maintenance costs, but also loss of the groundwater connection between land and sea and the accompanying loss of mudflat habitat and associated oyster, abalone, and seaweed fisheries.

While the frameworks for the economic analyses have been developed, the science to properly parameterize the models is still being conducted at our three study sites. We will continue to improve our models and complete the analyses as more data becomes available. The 5-year/5-country (also U.S, Canada, Indonesia, and the Philippines) project will conclude in 2018.

Kimberly Burnett

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