APEGBC Sponsors Province-wide Seminar Series on Rainwater Runoff Modeling
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 runoff modeling. Regional events conducted by Dumont in 2006 were held in Surrey (April), Nanaimo (July) and Terrace (November).
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
A recognized specialist in hydrologic modeling, Jim Dumont has almost 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. For more information, please click here.
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.”
Posted August 2006