Note to Reader:
This Primer is the second in a series of guidance documents released by the Partnership for Water Sustainability since November 2011. Core concepts presented in these companion documents provide an educational foundation for rainwater management in a watershed context. To download a copy, click on Primer on Urban Watershed Modelling to Inform Local Government Decision Processes.
Guidance in Three Areas
Released in November 2011, the purpose of the Primer on Urban Watershed Modelling to Inform Local Government Decision Processes is to provide engineers and non-engineers with a common understanding regarding ‘appropriate and affordable’ computer modelling. A guiding principle is that the level and/or detail of modelling should reflect what information is needed by local government to make an informed decision. The Primer elaborates on:
- Performance Targets: brings forward a synopsis of key information from Stormwater Planning: A Guidebook for British Columbia
- Levels-of-Service:explains why and how the major financial challenge resulting from the ‘unfunded infrastructure liability’ is a driver for a life-cycle approach to asset management and renewal
- Screening / Scenario Tools: introduces the ‘Drainage Infrastructure Screening Tool’ for establishing priorities and making budget decisions for storm sewer system upgrading; and describes the application of the ‘Water Balance Model powered by QUALHYMO’ for establishing watershed-specific performance targets.
“By addressing what appropriate and affordable should mean in practice, the Primer deals with two separate dimensions of an Integrated Watershed Management Plan. The first is the watershed itself, where the focus is on the relationship between rainfall and resulting flow rates in streams. The second is the storm drainage system, where the focus is on infrastructure and the level of service,” states Jim Dumont, Engineering Applications Authority for the Water Balance Model Partnership.
From the stream health perspective, appropriate and effective green infrastructure is a way to increase the level-of-service. Expressed another way, green infrastructure that restores the rainfall absorption capacity of the watershed landscape will increase the level of ecological protection.
“For storm sewer systems, the process of establishing an acceptable ‘Level-of-Service’ will require local governments to review, examine, and justify the existing standards and how to transition into the future where costs must be balanced against public needs and expectations,” concludes Jim Dumont.
TO LEARN MORE:
To download a copy, click on Primer on Urban Watershed Modelling to Inform Local Government Decision Processes.