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Economic Currents

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Publication: Who Are we Measuring and Modeling for? Supporting Multilevel Decision‐Making in Watershed Management

Posted January 24, 2020 | Categories: Blog, Water Resources

UHERO and an international partnership, ClimateWise, tackled the question of how hydrological ecosystem service information is actually used in decision making in watershed management programs. Linking hydrological monitoring and modeling efforts to actual user needs increases the relevance and uptake of these studies and has important implications for where researchers should focus their energy. As always, relationships and local champions matter a lot in the actual use of this type of information, and use is often in unexpected ways.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019WR026011


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


Understanding the Links Between Local Ecological Knowledge, Ecosystem Services, and Resilience

UHERO’s Project Environment has received funding from the National Science Foundation to participate in an interdisciplinary, international project that spans the natural and social sciences as well as the terrestrial and marine spheres. UHERO is partnering with scientists, resource managers, cultural practitioners and private landowners in Hawaii and Fiji. The project has two distinct parts; the first examines the relationship between local ecological knowledge and social, economic, and ecological outcomes across twenty rural villages in Fiji. The second part of the project explores the effects of different management and climate change scenarios on ecosystem services and indicators of resilience in three Pacific island watersheds.

For Part 1 of the project, we will focus on twenty rural coastal communities across four districts in Fiji. The team will collect household and village-level data within each of the four districts on ecological knowledge, customary skills and intergenerational knowledge. This will be matched to new and existing data collected from nearby forests and reefs. The goal is to develop an index of local ecological knowledge, as well as an index of social-ecological resilience, and examine relationships between these new indices and other ecological, social and economic outcomes. Of particular interest is the influence of local ecological knowledge on our indicators of resilience.



In Part 2 we will conduct three in-depth case studies at the watershed level, focused on quantifying ecological, cultural, and economic values of various land/ocean uses and covers, and their implications for resilience to climate change. The three watersheds were chosen where collaborators have long-term studies to leverage strong existing relationships with landowners, resource managers and users. The watersheds include Kaupulehu on the leeward coast of Hawaii Island, Haena on the north shore of Kauai, and Kubulau on southwestern Vanua Levu.

In each watershed we will collect new terrestrial data on vegetative composition, canopy cover, and indicators of habitat connectivity. Marine ecological surveys will include reef fish assemblages, benthic cover, species composition, biomass, and trophic structure. Ecosystem and cultural services for land and ocean uses will be calculated based on existing data, ecological characteristics, participatory mapping, and interviews.

To understand what combination of land-use practices best enhance social-ecological resilience under different climate change scenarios, we will evaluate the levels and resilience of ecosystem services under multiple future scenarios of climate change and management. These scenarios will represent a range of likely future climates crossed with a range of possible management decisions for each of the three watersheds. After developing an understanding of the ecological, cultural, and economic benefits of each of the management scenarios, we will then assess the costs of various management regimes under different climate change scenarios. The team can then identify a series of “optimum” scenarios – those that appear to maximize resilience indicators and emphasize the cultural, economic and ecological values identified to be of interest to the community members, land managers, and other stakeholders.

Our dual focus on Hawaii and Fiji provides a spectrum of cultural values and land and ocean uses, from functional agroforestry and traditional subsistence fishing in Fiji, to systematic habitat conservation and restoration in Hawaii. As a result, we can capture a wide spectrum of land management paradigms and their potential outcomes under different climate change scenarios, and our results can inform decision making elsewhere in Hawaii, in the Pacific, and throughout coastal areas more broadly.

-Kim Burnett and Cheryl Geslani


How Do We Manage Our Interdependent Environmental Resources?

Managing water resources requires an understanding of the linkages between key hydrologic factors and direct human influences. The problem is further complicated by the fact that water resources are often interdependent, which suggests that management should also account for ecological interlinkages. For example, a forested upstream watershed may replenish an underlying groundwater aquifer, or a coastal groundwater aquifer may provide positive spillover effects to a downstream nearshore resource such as a fishery. Left unregulated, these spillover effects are economic externalities—additional, unintentional costs or benefits. In general when private parties act in their self-interest in the presence of externalities, the outcome may not be the best for society.

The Kukio Region: Groundwater and Limu

In an application to the Kukio region on the Big Island, Pongkijvorasin et al. (2010) explore how the relationship between submarine groundwater discharge (SGD) and a keystone algal species, Gracilaria coronopifolio (“limu”), in the nearshore affects optimal water management. Lab experiments suggest that moderate levels of SGD influx to a coastal marine environment increase the growth rate of limu due to resulting changes in nutrient loads, temperature and salinity (Duarte et al., 2010). A reduction in the aquifer, and hence SGD, generates a negative externality since there is less water entering the coastal environment. This study shows that optimal water management before accounting for the limu involves only slightly higher water pumping rates (roughly 6 million  per year over 100 years in both cases) because the market value of algae is relatively small compared to the benefits of water consumption. However, the market value of limu does not include ecological and cultural values. One way to account for values that are difficult to monetize is a minimum algae-level constraint. If the stock of limu is constrained to be no less than 90% of its current level, the effect on optimal extraction rates is much more dramatic: extraction starts at approximately 4 million  per year, falls to 3 million  annually by year ten, and stabilizes at less than 0.5 million  per year from year 22 onward.

Incentivizing Externalities

Once we understand how optimal resource extraction rates change in the presence of an externality, the next question is how do we internalize it? In other words, what can we do to incentivize private actors (e.g. water consumers) to behave in a way that provides the most benefits to society? When the externality is negative, as is the case where reducing the groundwater stock slows limu growth in the nearshore, a corrective tax can be implemented to reduce groundwater extraction and increase the benefit of higher groundwater levels over a longer period of time. When the externality is positive, as is the case when watershed conservation activities increase recharge for a downstream aquifer, the socially optimal level of conservation can be incentivized using payments or subsidies. As the number of positive and negative externalities within a water management system increases, so does the complexity of the optimal tax/subsidy formula. Nevertheless, advancing methods for managing linked natural systems is important, especially in the context of water resources, given trends of increasing scarcity worldwide and the expected effects of climate change.

-Christopher Wada

 

References:

Duarte, T.K., Pongkijvorasin, S., Roumasset, J., Amato, D. and K. Burnett (2010), ‘Optimal management of a Hawaiian Coastal aquifer with nearshore marine ecological interactions’, Water Resources Research46, W11545.

Pongkijvorasin, S., J. Roumasset, T.K. Duarte and K. Burnett (2010), ‘Renewable resource management with stock externalities: Coastal aquifers and submarine groundwater discharge’,Resource and Energy Economics32, 277-291.
 

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