APEGBC Sponsors Province-wide Seminar Series on Rainwater Assessment and Mitigation




Going Beyond the Guidebook – Linking Analytical Techniques and Methodologies to Stream Health

Urban rainwater management and the associated processes have been linked to adverse impacts on aquatic environments.

Building on the interest generated by a rainwater management presentation that Jim Dumont made at a land development seminar held in January 2006, the Association of Professional Engineers and Geoscientists of BC (APEGBC) has undertaken a province-wide program of introductory seminars on rainwater management and mitigation. To date, regional events in the Rainwater Assessment Series have been conducted by Dumont in these cities:

  • Surrey(April 2006)
  • Nanaimo (July 2006)
  • Terrace(August 2006)
  • Vancouver(March 2007)
  • Kamloops(May 2007)
  • Castlegar(August 2007)
  • Kelowna(October 2007)
  • Victoria(August 2008)
  • Prince Rupert (November 2008) – tentatively scheduled

In March 2008, APEGBC commenced a second series of province-wide seminars to supplement the Rainwater Assessment Series. The sessions in the second series are intended to provide a foundation of knowledge to those professionals just starting in the field and as a review for more experienced practitioners.


Scope of Seminars

Because regulatory agencies are actively pursuing the implementation of ‘impact neutral’ infrastructure projects and urban development, the APEGBC-sponsored program provided an introduction into analytical techniques and methodologies that can be used to quantify impacts and impact reduction methodologies. The program content  was tailored for engineers working in urban infrastructure planning and design and the land development industry. Topics covered include:

  • Why is this topic important?
  • Overview of regulatory setting in British Columbia
  • Simulation models and their limitations
  • Model calibration and verification process
  • Stream flow duration estimation
  • Potential stream erosion estimation
  • Water quality modelling and its limitations

Showcasing innovation in surrey - jim dumont (200 pixels)A recognized specialist in hydrologic modeling, Jim Dumont  has over 30 years experience in the fields of water resources and civil engineering, including all phases of planning, design and construction. Of particular relevance, he is a member of the Project Team that the Inter-Governmental Partnership has assembled to integrate the Water Balance Model with QUALHYMO, thereby providing expanded functionality for ‘green’ subdivision design and rainwater runoff conveyance.


Going Beyond the Guidebook

“There is a need for a new approach to hydrologic design. A key message is that a rainfall-based approach does not work effectively. This is why I advocate a runoff-based approach. Duration of discharge is important because it links directly to stream health”, stated Jim Dumont.

Published in 2002, Stormwater Planning: A Guidebook for British Columbia formalized a science-based understanding to set performance targets for reducing rainwater runoff volumes and rates. The Guidebook formalized the Integrated Strategy for Managing the Complete Spectrum of Rainfall Events as the foundation for a “design with nature” approach to rainfall capture and runoff control. The key to implementing the strategy is that most of the annual rain volume falls as light showers.

Jim Dumont has developed an approach that “goes beyond the Guidebook” because it is built around a science-based methodology that correlates runoff volume (and hence volume reduction measures) with stream health as measured by erosion and sedimentation. In short, he has taken performance target thinking to the next level of detail.

According to Jim Dumont, “The objective in applying this refinement of the performance target methodology is to establish what level of runoff volume reduction is optimal. Continuous simulation of the rainfall-runoff response for the Fergus Creek watershed in the City of Surrey shows, for example, that full implementation of volume reduction measures for all land uses would actually remove all the baseflow from the creek. Clearly, this outcome would be detrimental to the aquatic resource. This finding provided the impetus to determine the optimum combination of volume reduction measures, both for new development and retrofitting of existing development.”


Fergus watershed - jim dumont's discharge exceedance graphic

For more information about the Beyond the Guidebook initiative, click here.


Posted August  2006

Updated April 2007