Vision for "Water Balance Model Express" introduced to elected representatives in Metro Vancouver


Note to Reader:

In May 2010, the Metro Vancouver region adopted a holistic strategy for managing liquid discharges and rainwater resources. Two years in the making, the Integrated Liquid Waste & Resource Management Plan established the framework for moving beyond regulatory compliance to transitioning Metro Vancouver to an approach where watershed-based planning is integrated within a broader, sustainability framework.

In February 2011, the Partnership for Water Sustainability in British Columbia released a guidance document to help municipalities implement a course correction in the way ‘Integrated Stormwater Management Plans’ (ISMPs) are undertaken.

In June 2011, the Minister of Environment announced that the Province has approved Metro Vancouver’s visionary plan. He also strengthened the plan by imposing conditions that expand what is expected of Metro Vancouver member municipalities vis-à-vis rainwater management. The ISMP Course Correction is aligned with the Minister’s conditions.

The Water Balance Model is a key tool for the Metro Vancouver region and member municipalities to meet their ISMP regulatory commitments. In September 2011, the Water Balance Model was the subject of a presentation to the Metro Vancouver Waste Management Committee. The presentation introduced the Partnership’s vision for addressing the ‘missing link’ in protecting stream and watershed health.

No Net Impact on Stream Environments

Originally developed to meet the stormwater management planning needs of Metro Vancouver municipalities, use of the Water Balance Model (WBM) informs decisions about a community’s ‘water footprint’. While it had a Metro Vancouver genesis, it has become “British Columbia’s tool”.

Integrate the Site, Watershed and Stream

Release of Version 2.1 on a new platform complete with a rebuilt website in November 2011 will provide an operating environment that supports user communities that range from highly experienced experts to enthusiastic newcomers. Three launch buttons will correspond to three common investigation scenarios:

  • WBM for the Watershed– this is the scale where watershed behaviour and stream erosion prevention is analyzed for achievability of performance targets and protection of stream health.
  • WBM for the Neighbourhood– this is the scale where the combined performance of on-lot rainfall capture measures and community detention ponds is analyzed for effectiveness.
  • WBM Express for Homeowners – this is the single family lot scale, and is especially relevant to house replacement scenarios that create opportunities to ‘do it right’ the second time.

Kim Stephens, Partnership Executive Director, introduced Metro Vancouver regional politicians to the vision for the WBM Express for Homeowners.

Vision for the WBM Express

“The region and member municipalities have committed to protecting stream and watershed health. This will be achieved by managing rain where it falls, stated Kim Stephens. “Stream health depends on ALL properties in a watershed. We have known this since the 1990s.”

Kim stephens (120p) - 2009“The ‘missing link’ has been the single family detached dwelling. We now have the tools and experience to manage rain where it falls. Addition of the WBM Express to the toolkit will help municipal front counter staff show homeowners HOW to reduce their Water Footprint.”

“The vision for the WBM Express is that homeowners will be able to type in their address, access a version of the WBM that has pre-set values (for climate, land use), select and apply from a suite of source controls for rainfall capture, run scenarios, and print a report.”

“The ultimate target actually audience goes well beyond homeowners. The Partnership sees the WBM Express as a vehicle to connect with builders, developers, consultants, real estate agents and students/educators.”

“The WBM Express will open the door to an array of educational opportunities. It will be a resource for developers and others to help the public understand the effect of their choices and decisions on the natural environment,” concluded Kim Stephens.

To Learn More:

Click on the following links to download report-style PDF documents:

Water Balance Methodology

Kim Stephens also provided this historical perspective: “UniverCity, the sustainable community atop Burnaby Mountain, was the catalyst for reinventing urban hydrology. This resulted in the Water Balance Methodology. That was more than a decade ago. At the same time, the City of Surrey was planning its East Clayton sustainable community. Surrey built on the UniverCity experience and evolved the Water Balance Methodology through a succession of watershed applications.”

In 2000, translating high expectations for UniverCity into practical design guidelines meant revisiting accepted drainage engineering practice. It meant demonstrating how to implement the Water Balance Methodology. The UniverCity precedent set in motion a chain of outcomes that has resulted in British Columbia being recognized internationally as a leader in achieving ‘design with nature’ outcomes in an urban environment.

The Water Balance Methodology enables correlation of green infrastructure effectiveness in protecting stream health. The reason is that rainwater runoff volume management is directly linked to stream erosion and water quality.

To Learn More:

Click on  UniverCity Leads Way with Next Generation of Green Infrastructure Innovation

City of Surrey Innovation

With hindsight, the significance of East Clayton is two-fold. It was an early application of performance targets at a neighbourhood scale. Also, and most importantly, the analysis combined mass balance and flow duration to test the achievability of performance targets.

But it was the City of Surrey’s South Newton case study where the methodology came together in terms of how to integrate the mass balance and stream erosion analyses. Until then, they were separate analyses.

The experience gained in East Clayton and South Newton was then applied in Fergus Creek. The methodology was formalized as the Stream Health Methodology, and subsequently incorporated in the Water Balance Model when it was integrated with the QUALHYMO engine. The Stream Health Methodology is a function of flow duration, and hence stream erosion.