Landscape / Watershed Landscape / Watershed ConservationConservationJolie R. WangerJolie R. WangerSmart Trees Pacific / Earthwise ConsultingSmart Trees Pacific / Earthwise Consultingjoliewanger@gmail.comjoliewanger@gmail.com

Flow of Water – Natural Flow of Water – Natural HydrologyHydrology

Graphic: PBR Hawai`i

Flow of Water – Altered Flow of Water – Altered HydrologyHydrology

Graphic: PBR Hawai`i

This is This is deliberate. deliberate.

Designed for Designed for flood controlflood control

• Excessive concrete Excessive concrete designed to convey designed to convey water water AWAYAWAY

• Landscaping Landscaping disconnected from disconnected from flow of waterflow of water

• Water treated as a Water treated as a problem rather than problem rather than a resource.a resource.

Major Major Problems:Problems:

• Modified (lined, Modified (lined, channelized) channelized) Streams = Streams = too much too much water volume/ water volume/ velocity velocity = erosion, = erosion, flooding, etc.flooding, etc.

• Impervious surfaces Impervious surfaces (residential, (residential, commercial & roads) commercial & roads) = = disturbed disturbed hydrologic cyclehydrologic cycle

• Sediment and Sediment and nutrientsnutrients

• System perfect System perfect design to cause design to cause imbalance in imbalance in environment.environment.

More runoff

Arriving faster

Ecological Ecological EffectsEffects

•Sediment smother’s Sediment smother’s marine life and marine life and disrupts disrupts reproductionreproduction

•Excess nutrients Excess nutrients cause cause algae bloomsalgae blooms

•Toxins from roads Toxins from roads and residential/ and residential/ commercial activities commercial activities kill marine lifekill marine life

•Concrete channels Concrete channels heat upheat up discharged discharged water water Bob Richmond

Impervious Impervious WatershedsWatersheds

Points of Points of Concern Concern

o Hawaii mostly Hawaii mostly characterized by short, characterized by short, steep basinssteep basins

o Impervious surfaces in Impervious surfaces in flat, lowlandsflat, lowlands

o Excess sediment and Excess sediment and nutrientsnutrients

o Excess nutrients feed Excess nutrients feed alien algaealien algae

o Excess freshwater and Excess freshwater and sediment a deadly sediment a deadly combination for corals.combination for corals.

Impervious cover threshold 25-

30%

Impervious cover threshold 25-

30%Sensitive elements affected at only

10%

Increased flooding

Increased flooding

Situation in Hawai`i (Oahu) More Situation in Hawai`i (Oahu) More Extreme Than Many Other Places:Extreme Than Many Other Places:

--Short, steep watershedsShort, steep watersheds-Many highly impervious watersheds-Many highly impervious watersheds-Very sensitive environment -Very sensitive environment -Climate change predictions-Climate change predictions-Limited space for development-Limited space for development

What To Do?What To Do?

Take the top off the curve by encouraging more water to soak into the ground instead of running off.

Engineering vs. Engineering vs. GardeningGardening

EngineeringEngineering

Expensive retrofitsExpensive retrofits

Often require spaceOften require space

Time consuming Time consuming planning and permittingplanning and permitting

Favors functionality Favors functionality over aestheticsover aesthetics

Maintenance planMaintenance plan

GardeningGardening

InexpensiveInexpensive

Maximize available open Maximize available open spacespace

Diffuse solution- treats Diffuse solution- treats water where it fallswater where it falls

Aesthetic and functionalAesthetic and functional

Requires commitment to Requires commitment to care for plantscare for plants

Maximizing Ecosystem Maximizing Ecosystem Services in GI Designs Services in GI Designs

• TREES – intercept rainfall, TREES – intercept rainfall, root structure, root structure, evapotranspirationevapotranspiration

• PLANTS AND SOIL – PLANTS AND SOIL – pytoremediation, microbespytoremediation, microbes

• WATER WATER RETENTION/INFILTRATION – RETENTION/INFILTRATION – slows down runoff, reduces slows down runoff, reduces volumevolume

• IMPERVIOUS SURFACES IMPERVIOUS SURFACES ARE REMOVED – increase ARE REMOVED – increase available infiltration areas.available infiltration areas.

Watershed ScaleWatershed ScalePlanning ApplicationPlanning Application

Impervious surfaces for the Kailua urban realm = 22.7%

~ 39% grass &

soil

Mahalo!Mahalo!

Jolie R. WangerJolie R. WangerSmart Trees Pacific / Earthwise ConsultingSmart Trees Pacific / Earthwise Consultingjoliewanger@gmail.comjoliewanger@gmail.com