1. Landscape / Watershed Conservation Jolie R. Wanger Smart Trees Pacific / Earthwise Consulting joliewanger@gmail.com

2. Flow of Water – Natural Hydrology Graphic: PBR Hawai`i

3. Flow of Water – Altered Hydrology Graphic: PBR Hawai`i

4. This is deliberate. Designed for flood control Excessive concrete designed to convey water AWAY Excessive concrete designed to convey water AWAY Landscaping disconnected from flow of water Landscaping disconnected from flow of water Water treated as a problem rather than a resource. Water treated as a problem rather than a resource.

5. Major Problems: Modified (lined, channelized) Streams = too much water volume/ velocity = erosion, flooding, etc. Modified (lined, channelized) Streams = too much water volume/ velocity = erosion, flooding, etc. Impervious surfaces (residential, commercial & roads) = disturbed hydrologic cycle Impervious surfaces (residential, commercial & roads) = disturbed hydrologic cycle Sediment and nutrients Sediment and nutrients System perfect design to cause imbalance in environment. System perfect design to cause imbalance in environment. More runoff Arriving faster

6. Ecological Effects Sediment smother’s marine life and disrupts reproduction Sediment smother’s marine life and disrupts reproduction Excess nutrients cause algae blooms Excess nutrients cause algae blooms Toxins from roads and residential/ commercial activities kill marine life Toxins from roads and residential/ commercial activities kill marine life Concrete channels heat up discharged water Concrete channels heat up discharged water Bob Richmond

7. Impervious Watersheds Points of Concern o Hawaii mostly characterized by short, steep basins o Impervious surfaces in flat, lowlands o Excess sediment and nutrients o Excess nutrients feed alien algae o Excess freshwater and sediment a deadly combination for corals. Impervious cover threshold 25-30% Sensitive elements affected at only 10% Increased flooding

8. Situation in Hawai`i (Oahu) More Extreme Than Many Other Places: - Short, steep watersheds -Many highly impervious watersheds -Very sensitive environment -Climate change predictions -Limited space for development

9. What To Do? Take the top off the curve by encouraging more water to soak into the ground instead of running off.

10. Engineering vs. Gardening Engineering Expensive retrofits Expensive retrofits Often require space Often require space Time consuming planning and permitting Time consuming planning and permitting Favors functionality over aesthetics Favors functionality over aesthetics Maintenance plan Maintenance plan Gardening Inexpensive Inexpensive Maximize available open space Maximize available open space Diffuse solution- treats water where it falls Diffuse solution- treats water where it falls Aesthetic and functional Aesthetic and functional Requires commitment to care for plants Requires commitment to care for plants

11. Maximizing Ecosystem Services in GI Designs TREES – intercept rainfall, root structure, evapotranspiration TREES – intercept rainfall, root structure, evapotranspiration PLANTS AND SOIL – pytoremediation, microbes PLANTS AND SOIL – pytoremediation, microbes WATER RETENTION/INFILTRATIO N – slows down runoff, reduces volume WATER RETENTION/INFILTRATIO N – slows down runoff, reduces volume IMPERVIOUS SURFACES ARE REMOVED – increase available infiltration areas. IMPERVIOUS SURFACES ARE REMOVED – increase available infiltration areas.

15. Watershed Scale Planning Application Impervious surfaces for the Kailua urban realm = 22.7% ~ 39% grass & soil

16. Mahalo! Jolie R. Wanger Smart Trees Pacific / Earthwise Consulting joliewanger@gmail.com