“We have observed that the power of the Water Balance Model process lies in the conversations that result from users generating a single number – the percentage of rainfall that becomes runoff – that represents the synthesis of any particular scenario. Comparison of scenarios creates understanding, especially when the focus is on the hydrologic implications of the assumptions that underpin those percentages," stated Ted van der Gulik.
“When we wrote the Guidebook, we recognized there is a material difference in the characterization of surface runoff that originates from an individual development site versus flow that you see at a catchment or watershed scale. What you see in a watercourse is the total flow – that is, water that flows overland plus water that moves through soil until it daylights," stated Peter Law.
"The stream health methodology embedded in the Water Balance Model enables a watershed target to be established. It also enables the user to assess how to meet the watershed target at the site scale. This helps planners and designers wrap their minds around how to implement ‘design with nature’ solutions on-the-ground,” explains Ted van der Gulik.
"The rule proposal would expand the universe of regulated stormwater discharges, requiring new controls for newly developed and redeveloped sites and possibly even old developments. It could also expand the number of cities and towns regulated as Municipal Separate Sewer Systems (MS4s) under the Clean Water Act," wrote Annie Snider.
According to Jeremy Bauer, "Key elements of the rule’s approach include integrating green infrastructure into project design, viewing stormwater as a resource, and generally slowing the flow of runoff to allow more infiltration, which will not only reduce the volume of runoff but also the amount of pollutants reaching receiving waters."
"The clay soils and limited infiltration rates drove innovation in both the calculation methods and the design details to allow the volumetric runoff coefficient to be maintained in both single family and multi-family sites," states Jim Dumont.
“A decade of on-the-ground experience has enabled the City of Surrey to move beyond pilot projects to a broader watershed objectives approach to on-site rainfall capture. As we move forward, the new Drainage By-Law endorsed by Council in 2008 is the tool that will enable the City to establish watershed-specific performance targets for rainwater runoff volume and rate reduction," states Remi Dubé,
"Our community wash-off models have for 40 years been structured based on land use: residential, commercial, and industrial. The deep weakness of such models is that the structure is not directly related to the BMP programs. Let’s consider structuring our models based on scape: roadscape, parkingscape, roofscape, and landscape," writes Gary Minton.
"The goal of the Learning Lunch Seminar Series is to inform and educate local government practitioners," stated Kim Stephens. "The series is the first step in building a regional team approach.....so that there will be a common understanding and consistent messaging regarding on-the-ground expectations for rainwater management and green infrastructure."
“Once we went back to basics and developed the concept of a Rainfall Spectrum, this then led into the concept of Performance Targets for rainwater runoff capture. The reason runoff percentage is the performance target is that municipalities exert control over runoff volume through their land development and infrastructure policies, practices and actions," explained Kim Stephens.
A scenario comparison tool to assess green infrastructure effectiveness, achieve a lighter 'water footprint' and protect stream health. Learn More
The Water Conservation Calculator illustrates how specific water conservation measures can yield both fiscal and physical water savings for communities. Learn More
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The BC Agriculture Water Calculator enables water licensing for all irrigation purposes, whether agricultural or landscape. All non-domestic users of groundwater in BC are required to obtain a licence. Learn More