Photo: Ambleside Beach, WV February 25, 2017 EXPLORING THE WATER BALANCE on your property Julie Wilson julie.wilson@ubc.ca NSSK Workshop, Mar. 18, 2017
My Goal dnv.waterbalance dnv.waterbalance dnv.waterbalance dnv.waterbalance- - - -express.ca express.ca express.ca express.ca geoweb.dnv.org geoweb.dnv.org geoweb.dnv.org geoweb.dnv.org
Image: NOAA National Weather Service
Water Balance Image: US EPA
Stream Discharge Response after a Storm Difference in Stream Discharge between Urban and Forested Watershed Event in a Forested Watershed 18 18 16 16 Stream Discharge (m 3 /sec) Stream Discharge (m 3 /sec) 14 14 12 12 10 10 8 8 6 6 4 4 2 2 0 0 Time after Precipitation Starts Time after Precipitation Starts
Water Quality Concerns www.belairks.org Photo credit: Charles Crawford; courtesy USGS Pollutants • Metals (Cu, Zn, Pb, Ni, Cr, Hg, Cd, As) • Organics (Hydrocarbons, Oil, Grease) • Nutrients (N, P)
Aquatic Ecosystem Health Source: H. Schreier
Green Grey Infrastructure Infrastructure Infiltration Swales Julien Interior Rain Gardens Constructed Wetlands Rain Barrels Flynn Canada Green Roofs
Mimic the Natural Water Balance Three flow pathways: Surface runoff 1. Seasonal interflow (shallow 2. horizontal flow) Water stored deep in aquifers 3. which then discharges at some future date. “SLOW, SINK AND SPREAD” THE WATER! Image: Auckland City Council (2010) - Partnership for Water Sustainability in BC
Urbanization Trends 2003 Impervious Area 2009 Impervious Area 23% 54% Source: D. Freudiger, 2012
Urbanization Trends 160 Age of Houses 140 Houses rebuild (hypothetic) 120 Number of houses 100 80 60 2003 Impervious Area 2009 Impervious Area 40 23% 54% 20 0 1910-1914 1920-1924 1930-1934 1940-1944 1950-1954 1960-1964 1970-1974 1980-1984 1990-1994 2000-2004 2010-2014 2020-2024 2030-2034 2040-2044 2050-2054 2060-2064 Time period (5 years) Source: D. Freudiger, 2012
Water Balance Model Express Image: waterbucket.ca
Watershed-Specific Targets • The flow-duration relationship is the cornerstone of the methodology. • By maintaining flow-duration, • stream erosion is not increased during wet weather, and • ‘environmental flows’ are sustained during dry weather. • Considers local environmental constraints Credit: Jim Dumont, Engineering Applications Authority, Partnership of Water Sustainability in BC
DEMONSTRATION Check out the video tutorial at dnv.waterbalance-express.ca GeoWEB at geoweb.dnv.org
Design Considerations • Be aware of your site limitations • Consult a professional • Resource: Metro Vancouver Stormwater Source Control Design Guidelines (2012)
Relevant Policies • Integrated Stormwater Management Plans • Top Soil Bylaws • BC Water Sustainability Act • “Environmental Flow Needs” must be considered
Key Messages Singing in the rain! • Goal: Water balance of the urbanized watershed to mimic the water balance of the pre-development watershed. SLOW, SINK AND SPREAD • Try the WBM Express! • Change the way you look at rainwater and how it moves through the urban landscape. Image: Tomas Castelazo, Wikimedia Commons
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Happy World Water Day! March 22 Waiting for Water Linocut by Catherine Fenton
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