Geography.hydrology

Urban Hydrology: theory and new approaches for stormwatermanagement

Jack Ahern, Professor Dept. of Landscape Architecture and Regional PlanningUMass Amherst

“The site is to the watershed as the cell is to the body”Patrick Condon, 2000

Hydrograph

Subtitle

Urban Conditions: Impervious Surface Cover

Subtitle

Increased impervious surface increases runoff, decreases evapotranspiration, and decreases infiltration

Percentage of Impervious Surfaces

Presenter

Presentation Notes

In an urban watershed, impervious surfaces like roads and parking lots prevent water from soaking into the ground. Water travels quickly over these surfaces and pollution is concentrated in pipes and culverts before it is emitted into a stream. This is known as non-point pollution As Patty spoke of, in an undisturbed condition, the earth absorbs water like a sponge. As rain and snowmelt percolate down from the surface, impurities are filtered through biological processes in soil. The infiltration process recharges groundwater where it feeds into streams as BASE FLOW. The water that is feeding into our streams right now through baseflow, is from the snowmelt in February.

Urban Hydrology

Non-point source pollutants

Subtitle

Increased Impervious Cover Affects the Number and Quality of Aquatic Lifee

Stormwater: The Conveyance Approach

Stormwater conveyance is the rapid removal of stormwater from impervious surfaces to receiving streams by way of engineered

drainage systems (e.g. culverts, stormdrains, and channelized streams and rivers).

“water is a problem. Its the enemy. Get itaway from here.

NOW!”

Stormwater: The Infiltration ApproachInfiltration is the the retention of stormwater as close as possible to its originating source(s), and infiltrating as much as possible into the soil through the implementation of best management practices and strategies.

“water is a precious resource, keep it here, clean it, save it for later - we need it, and our local our ecosystems need it too!”

Guidelines:1. Start at the source2. Integrate the solutions3. Maximize permeability4. Minimize directly

connected impervious areas5. Use drainage as a designelement

Stormwater Best Management Practices (BMP’s)Greenroofs

Stormwater Best Management Practices (BMP’s)

Rainbarrels

Stormwater Best Management Practices (BMP’s)Raingardens

Stormwater Best Management Practices (BMP’s)Raingarden with overflow

Stormwater Best Management Practices (BMP’s)Raingarden Interpretive Sign

Stormwater Best Management Practices (BMP’s)Streetside Raingarden

Stormwater Best Management Practices (BMP’s)Porous paving

Stormwater Best Management Practices (BMP’s)Porous paving

Stormwater Best Management Practices (BMP’s)Biofilter, created wetland

Stormwater Best Management Practices (BMP’s)Greenwalls

Integrated Solutions: Sustainable Community Design, Condon and Proft, Vancouver BC

Integrated Solutions: Green parking, Wild Center, NY

Integrated Solutions: SEA Street Seattle

Integrated Solutions: Green Corridors, Toronto

Integrated Solutions: Potsdammer Platz, Berlin, Atelier Dreisitl






Integrated Solutions: Kronsberg New Town, Hannover, Germany

Integrated Solutions: Kronsberg New Town, Hannover, Germany

Hammarby Sjostad, Stockholm150HA, mixed use brownfield development, 11,000 units, 25,000 population

Title The Hammarby Model: integrated, renewable, circular

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Title

Subtitle

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Stormwater Biofilter

Title

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UMass’ first raingarden/bioswaleLocation: North of Studio Arts BuildingDesign: Max Cohen, Michael Davidsohn, Jack AhernConstruction: Michael Davidsohn’s Stockbridge construction class + UMass Physical Plant

Title

UMass’ first raingarden/bioswale: Under construction

Summing up:

Start at the sourceIntegrate SolutionsUbiquitous InfiltrationLandscapes for Learning

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Geography.hydrology