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Photo: Christian Kahahawai
The Importance of Forests for Fresh WaterDepartment of Land and Natural Resources
Division of Forestry and Wildlife
August 2, 20182018 4th Joint Government Water Conference
“Protecting Hawaii’s Groundwater”
ABSTRACTHawaii's native forests absorb rain and cloud moisture across millions of acres ‐ and are the source of Hawaii's fresh water. At the same time, they help reduce erosion that can impact water quality and damage coral reefs. For over a century, public‐private partnerships have managed mauka forests by preventing the advance of invasive plants, animals and disease. This presentation will discuss the approaches to maukawatershed management in Hawai`i and the important role of the State's Division of Forestry and Wildlife and Watershed Partnerships in helping safeguard fresh water resources.
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Brief overview of your role and the role of DOFAW in managing forests/water resources.
DOFAW is responsible for managing over 1 million acres (a quarter of the land in the state). This includes mauka areas and places dominated by native forests that are critical to water recharge. As you can see this is a tremendous amount of acreage to manage. We can’t do it alone.
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I also work with groups called Watershed Partnerships who help the State manage Hawaii’s forests and mauka areas. Note: DOFAW lands included in WP boundaries.
The WPs began in East Maui in 1991 with the same goal as DOFAW – to protect forested watersheds for water recharge. Today, there are 10 active partnerships statewide. All the partnerships are made up of voluntary alliance of public and private landowners committed to the common value of protecting Hawaii’s watersheds for water recharge, biodiversity, and other ecosystem services. Each partnership has its own field crew and staff, including a coordinator who helps direct the work per the goals outlined in each management plan.
Because the WPs include public and private landowners, they help fill the management gaps. Invasive species don’t abide by TMKs. Later you will hear from [name of WP] about the specific work they do on the ground to protect our forested watersheds.
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Forests play a critical role in the water cycle. Not only do they absorb water (slowing it down and allowing it to seep into the ground and replenish aquifers). They also transpire and release water through their leaves back into the air, adding to the amount of water released by clouds as rainfall.
IMPORTANT! = healthy forests help sustain existing sources! It takes ~25 years for rainfall to reach the aquifer. We drink 25 year old water! Watershed protection is one part (arguably the first step!) in the larger picture of water security. We need our forests if we want to have water in the future.
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Source
Pipeline
Faucet
There are a lot of different agencies that oversee the protection and management of our water resources. This diagram is a simplified way of describing the relationship that these various agencies have to water.
DOFAW/WPs protect the “source,” the Board of Water Supply is the “pipeline,” and the Water Commission is the “faucet.” But to get water to go into the pipeline and out the faucet you must first protect the source.
Point out that the counties invest $ in watershed protection (BWS planning to fund $3m per year for watershed programs and Maui DWS awards over $2m annually). That funding, in addition to State, federal, etc. is helping support the protection of forests.
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Goals and Objectives of Watershed Protection
1) Investigate long-term, sustainable funding options to support the implementation of WP management plans
2) Address capacity-building needs3) Support policies and laws that will benefit WP goals and
management plans4) Facilitate annual watershed workshop and/or event to
maintain communication among partners and facilitate information exchange
5) Expand outreach and education initiatives to develop support among the public and decision makers
The Source!
What is the source? What do our forested watersheds look like?
In Hawaii our watersheds extends mauka to makai. Water collects at the summit and drains into a common outlet (the ocean). On its way to the ocean, water is absorbed into the ground or channeled into streams. A critical component of the watershed’s ability to capture and store that water is the existence of the forest.
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In Hawaii, the native forest has adapted to be super efficient at capturing and storing rainwater. It has a multi‐layer canopy of ferns, mosses, and trees, which help slow down the flow of water, allowing it to seep into the ground.
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In Hawaii, water capture and recharge is typically highest along the crest of the mountains at high elevation. Here our forests are dominated by native trees. Ohia make up 80% of our forests and watersheds.
On Kauai, native forests provide an estimated 412 million gallons of water per day(contributing to ~47% of island recharge).
The importance of our mauka forests for water capture is further demonstrated by a 2015 USGS Report on Oahu Groundwater Recharge which said that on Oahu, the northern section of the Koolau mountains receives as much as 180 inches of rain per year. Compared to undeveloped and non‐agricultural areas at low elevation, recharge is less than 5 inches per year.
100% of Oahu’s drinking water is coming from underground sources.
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Acknowledging the value of our forests for fresh water, DLNR has identified “priority watersheds”. These areas include high concentrations of native forest and areconsidered the best areas for recharge.
How Priority Watersheds I and II areas were determined:• Land cover types that provide the most groundwater recharge (GAP analysis –
landcover types, distribution of native vegetation types)• Elevation, rainfall and/or fog drip• Threat of conversation that would generally result in less recharge function, soil
retention, and an increase in runoff.• Mauka native forests that receive the most rainfall and are essential for sustaining
the State’s water resources, cultural and biological diversity• Priority areas are based on climatic conditions (elevation, moisture zones including
fog and rainfall levels), land cover types that provide high recharge and fog capture (native wet and mesic forest)
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Governor Ige’s
The State has a commitment to protect 30% (253,000 acres) of Hawaii’s priority watersheds by 2030.
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In order to reach the goal of 30% we need to protect approximately 9,000 additional acres every year.
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Green areas = what DOFAW has identified as “priority watershed” (areas with the highest rainfall that are critical to recharging our water supply).Purple = areas already under a high level of protection (aka: fenced or have natural barriers that keep it protected)Red = future areas proposed for protection. If we are able to protect the areas in purple we will meet our 2030 goal of protecting 253,000 acres.
Note FY19 CIP award of $7m+ which will fund some of these projects and protect an additional 23,000 acres.
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Photo: Ryan Chang
Photo: Kirsty Gallaher
Watershed management includes a suite of actions. Protection = acres fenced.
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“In Hawaii, the most valuable product of the forest is water, rather than wood”
– Ralph Hosmer First Territorial Forester
The goal of forest protection is not a new concept. Hawaii’s history of watershed protection began with the territory in the early 1900s. At that time, cattle and other introduced livestock were allowed to multiple and range unchecked throughout the islands resulting in the destruction of thousands of acres of native forests. The loss of the forest resulted in an alarming decrease in water supply. Territorial foresters recognized the need to protect the mauka forests to provide water for agriculture, especially sugarcane.
The push for protection led to hundreds of thousands of acres, of both public and privately owned lands, designated as Forest Reserve for the purpose of watershed protection (Act 44 on April 25, 1903). It also led to landscape‐scale reforestation projects. Even though less than ideal species were introduced (albizia) the concept of forest protection and restoration to bring back the water was valid. “The rain follows the forest” so where you have a forest, you also have water.
The primary purpose of the Forest Reserve System has not changed since it’s inception, and it currently protects 650,000 acres of Hawaii’s watershed. Water is the most important product coming out of the forest – not wood.
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Unfortunately, we are still dealing with the impacts of decades of unchecked grazing and deforestation. Over the last 200 years, over half of Hawaii’s forests have been lost. Places like the leeward slopes of Haleakala are still in the process of recovering. The loss of forests not only impacts water recharge, it also impacts water quality.
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Without forests, rain can quickly erode topsoil and cause flooding and landslides that impact our beaches, reefs, and fisheries downstream with muddy water. Studies have shown that forests can reduce erosion by 90%.
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Preliminary results of a Molokai erosion study by USGS indicate that after just 4 years of hoofed asediment eroding from the 3,300‐acre watershed decreased from 6 metric tons/year to 2 metric tto an increase in vegetative cover from 0% to over 70%.
Note: less DOT overtime pay as indicator of success.
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Forests are also important for their ability to capture water. In fact, conversion of native forests into non‐native forests can have possible negative effects on water processes.‐ Reduced soil infiltration rates‐ Reduced fog interception‐ Increased evapotranspiration
The morphological characteristics of native plants are thought to enhance water collection. Forests can absorb as much water as rainfall – doubling the amount of fresh water collected! (e.g. Kaʻala). *Note the word “collected” but not “recharge” because the forest is evapotranspiring water so it isn’t doubling recharge.
Conversely, non‐native plants have been shown to be 50% less efficient at collecting water than our native species. Why? Invasive plants are fast growing, must keep their stomata open for longer periods of time, more water escapes, less water recharged into ground. Certain non‐native species like strawberry guava also have smooth bark which allows water to runoff more easily and inhibits growth of epiphytes which can assist with water collection.
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Photo: Tom Giambelluca presentation
Certain invasive species, like strawberry guava, create monotypic stands and can outcompete native species.
Although we don’t know precisely how much recharge will be reduced by the conversion of native forests to non‐native vegetation, research shows that strawberry guava trees evapotranspire 27‐53% more water than native forests, causing extensive water loss (Giambelluca et al, 2008). In East Hawaii, non‐native vegetation has already reduced estimated groundwater recharge by 85 million gallons a day (Engott, 2011).
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We are also trying to understand the economic value of our protection efforts.
UHERO recently published findings on the economic value of watershed protection activities at TNC’s Waikamoi Preserve on Maui. While Waikamoi is currently under a high level of protection and management, this study looked at the value of total avoided loss by keeping forest native vs. allowing invasion to occur.
Waikamoi Preserve on Maui = 9,000 acres under active management by TNC.
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The research indicates that there is significant value in investing in the management of these forests for fresh water. If not protected, conversion to non-native forest would generally result in loss of recharge function and decline in water supplies.
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Value of Protecting Waikamoi Forest:
• Recharge 32.5 billion gallons of groundwater over next 100 years
• Produce $36.2 million worth of fresh water
• Prevent 4,300 tons of sediment per year from washing into ocean by 2072
That is enough water to fill 130 Olympic sized swimming pools with fresh water every day.
Mention other studies being done by Leah Bremer and Ike Wai to evaluate how groundwater recharge may change under a range of possible land use/land cover and climate futures for Pearl Harbor.
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Photo: The Nature Conservancy
USGS and researchers at UH (Tom Giambelluca) are also trying to gather species specific data to better understand how native and non‐native species impact hydrology and water supply.
This study started on Maui. Maui County DWS invests millions of dollars every year in watershed protection, but they are interested in better understanding the return on investment. With funding from Maui DWS and CWRM, USGS has identified sites where they can sample native and non‐native plant species.
This study has been expanded to include Kauai, Oahu, and Hawaii Island. The data will be used to help refine the water budget model, which we are using to estimate recharge. All our knowledge about effects of invasive plants on water processes is based on limited studies, on a few species, at a few sites.
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A lot of the data we use to better understand the impact of our management on ground water comes from USGS water budget model. Taking the data generated by this model, we have been able to estimate the amount of ground water recharged within our management areas.
Amount of mgd protected by investing in fences ‐ maps generated using USGS water budget data from Volcanic aquifers of Hawaii – Hydrology, water budgets, and conceptual models. Scientific Investigation Report 2015‐5164 https://pubs.er.usgs.gov/publication/sir20155164
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Groundwater Recharge
530 MGD
60% of island recharge
525 MGD
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KAUA`I WATERSHED ALLIANCE60% OF ISLAND RECHARGEMANAGEMENT UNITS
Management Units (170 MGD)KWA Boundary (525 MGD)Aquifer System (DLNR)
Based on “U.S. Geological Survey Scientific Investigations Report 2015‐5167: Volcanic Aquifers of Hawai`i – Hydrogeology Water Budgets, and Conceptual Models; Version 2; March 2018.”
NAME Recharge MGD
Alakai 17.78
Blue Hole 15.27
Drinking Glass 4.53
Halehaha 8.93
Hanalei 22.90
Iliiliula 8.96
Kanaele 0.37
Koaie 6.43
Laau 7.37
Lumahai 24.93
Mohihi 8.70
Namalokama 17.48
Wainiha 25.35
Map by Theresa Cabrera Menard, The Nature Conservancy of Hawai`i, March 2018
Map of estimated mean annual groundwater recharge for recent conditions (rainfall 1978‐2007, land cover 2010) on Kaua`i.
DRAFT
Alakai 18 MGDBlue Hole 15 MGD
Drinking Glass 4 MGD
Halehaha 9 MGD
Hanalei 23 MGD
Iliiliula 9 MGD
Kanaele 0.4 MGD
Koaie 6 MGD
Laau 7 MGD Lumahai 25 MGD
Mohihi 9 MGD
Namalokama 17 MGDWainiha 25 MGD
KEKAHA
NA PALI
WAINIHA HANALEI KALIHIWAI
KILAUEA
ANAHOLA
WAIMEA
HANAPEPEKOLOA
HANAMAULU
Existing and proposed management units = 170 mgd (19% of island recharge)
Estimates generating using existing data for water budget model. More studies are needed that look at species specific information. We don’t know the hydrologic impacts of Hawaii’s dominant plant species. The more data we can plug into the water budget model, the more refined these estimates can be.
Quantifying the exact effect on recharge remains a challenge. A lot more research is needed before we can definitely say how much recharge we get by protecting “x” amount of acres.
We would like to share with you estimated recharge values for each of Kauai Watershed Alliance’s (KWA) intensive forest conservation management units, thanks to TNC’s GIS specialist Theresa Menard who made this map. Each of these black lined units KWA is
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focusing management on has a disproportionately higher amount of recharge capacity on a per acre basis (as indicated by the blue and green areas). We encourage you to use these #s in your grant proposals or marketing 2‐pagers for these forests. While some of these black boundaries may change slightly in the future as protective watershed fences are constructed, such as Mohihi unit, the recharge #s shown here rounded to the nearest million gallons per day will likely stay the same. Aquifers that each unit contributes to are shown in white lines. The majority of groundwater recharge on Kauai occurs within the Kauai Watershed Alliance boundary shown in red.
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Kekaha Ditch catchments
RUNOFF20 MGD
12.5 MGD
10 MGD
Runoff derived from Izuka et al 2015 Volcanic Aquifers of Hawaii – Hydrogeology, Water Budgets, and Conceptual Models.
Recent water budget (1978‐2010 rainfall)
= Intake
Mānā Plain
Catchments calculated using Kauai 5m DEM & intake locations confirmed using Pictometry photos.
**6‐8 hours for water to travel from Koaie intake to Waimea Hydro18‐20 hours total from beginning to end**
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Microsorum spectrum, Pe`ahi
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2003 – Membership formed“The Mission of the Kaua‘i Watershed Alliance is to PROTECT, PRESERVE and MANAGE our valuable watershed resources for the benefit of our residents, communities and all future generations through the concerted efforts of its members.”
2003 ‐ 2005 – Management PlanTNC hired to complete a management plan for the membership.
2005 – Coordinator SecuredUpon completion of the plan, the membership needed an entity to coordinate the work and asked TNC to fulfill the position.
2012 – Management Plan updatedCoordinator revised plan to reflect progress and next steps for goals.
Kaua'i Watershed Alliance Key Dates
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WPs are soft funded. Point out that Kauai DWS provides funding for KWA.
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State Investments in Watershed Protection
Investment by State over last 7 years. State funds tend to fluctuate, which makes it difficult to plan management more than a couple years out.
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Kauai relies on both surface and ground water. Most of that water is coming from the Alakai plateau.
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CWRM is telling us that there are certain areas of the State that are seeing noticeable declines in ground water and that pumping levels (esp. on Oahu) are increasing and in some places we are close to reaching SY levels.
Yellow = we should be starting to monitor conditions as ground water use is exceeding 50% of the sustainable limit. Orange = use has reached 90% or higher and CWRM needs to designate the area if it hasn’t already. Red = ground water use has exceeded what we consider the sustainable limit, and means use should either decrease, or supply increased. Green = everything is fine in those areas at the current use rates.
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Kauaʻi Priority I Watershed
Total Acreage in Partnership: 146,388 acres
KWA Partner LandsKWA Partnership Boundary
Watershed Protection Priority I
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Fences:
2008 Kanāele2011 Wainiha2011 Alakaʻi Summit2017 Halehāhā2018+ Drinking Glass & Koaiʻe
Types of work:
‐ Planning ‐ Fence
Construction & Maintenance
‐ Weed Removal‐ Ungulate
Removal‐ Monitoring
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Fence Construction & Maintenance
• Strategic Fenclines
• Scouting
• Contracting
• Wing Fences
• Water…
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13 miles of fence built/maintained5.5 additional miles planned
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Ungulate Control• One‐way Gates
• Trapping
• Specialized Hunting
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7,000 acres cleared of pigs and goats to‐datePresence and impact of black‐tail deer increasing, new fences, new target species
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Weed Control
• Prioritize Species
• Contract Model
• Ground and Aerial Control
• Biological Control
• Adaptive Management
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Strawberry guava, Himalayan (Kahili/ Toilet Brush) ginger, Australian tree fernOver 2,500 acres of weed transects contracted through KRCP since 2006Combined with aerial control to treat ATF across rugged watershed terrainTectococcus (Strawberry guava) biocontrol trials on Big Island have been slow‐moving but gaining speed, long‐term positive impact. Others in progress, and needed, for ginger and others
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Monitoring
• Game Cameras
• Aerial Imagery
• Ungulate Activity
• Weed Populations
• Vegetation Recovery 9/5/2018 44
Game Cameras: Wide variety of models/price points, longevity is the key for remote monitoring workAerial imagery development for large‐scale forest monitoring good for changes to canopy or larger invasivesActivity over time, weed populations and vegetation recovery after removal
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400 Feet
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40 Feet
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