Funded by government, and implemented in 2003, the Water Balance Model is a scenario comparison and decision support tool. It operationalizes the Water Balance Methodology that is the technical foundation for Stormwater Planning: A Guidebook for British Columbia, released in 2002. The tool fills a gap not covered by commercial software.
The Guidebook established a guiding principle that achievable and affordable performance targets at the watershed scale provide a starting point to guide the land use actions of local government in the right direction. The Water Balance Model enables the user to evaluate and establish performance targets for rainwater capture and runoff control. The desired outcome is to protect and/or restore stream health.
Modules & Engine
The Water Balance Model allows modellers to complete computer simulations in minutes rather than taking days or even weeks.
Water Balance Modules include: Climate Change, Stream Erosion, Tree Canopy Rainfall Interception, Rainwater Harvesting.
The Water Balance Model is powered by the QUALHYMO calculation engine, which was developed by Dr. Charles Rowney for Ontario’s Ministry of Environment in the 1980s. The strength of QUALHYMO lies in the erosion and flow-duration routines.
DID YOU KNOW:
In 2004, the Canada Mortgage & Housing Corporation funded creation of a national portal, with the goal of encouraging use of the Water Balance Model across Canada. Because Environment Canada was co-chair of the inter-governmental partnership, this enabled access to the Atmospheric Environment Service climate station database. As a result, the Water Balance Model is populated with climate stations representing each province.
At the time of registration, the user selects the desired province. This automatically defaults the model to the stations within that province.
Additional climate stations will be uploaded upon request.
Understand the Watershed as a Whole System
“Unless and until land development practices mimic the natural water balance, communities cannot expect to restore the biological communities within streams. Simply put, hydrology hits first and hardest.”
Dr. Richard Horner, Professor Emeritus
University of Washington, Seattle
“To be useful…the simulation model must be physically based and deterministic, and it must be designed to simulate the entire hydrological cycle…hence it must be a water balance model.”
Dr. Ray Linsley (1917-1990), Professor
(author, innovator & pioneer modeller)
Stanford University, California
Water Balance Pathways
Watershed protection starts with an understanding of how water gets to a stream, and how long it takes (refer to illustration below). The flow of rainwater from cloud to stream is comprised of three water balance pathways:
- surface runoff;
- interflow; and
- deep groundwater (aquifer flow).
In coastal British Columbia, for example, interflow is the primary pathway in an undeveloped watershed. Therefore, it is deemed to be vitally important. In everyday language, interflow is defined as the shallow horizontal movement of water through the surface soil ‘sponge’.
Historically, the community development and infrastructure servicing process has overlooked, ignored or eliminated interflow.
Whole-System, Water Balance Approach
- Understand where the water goes naturally and reproduce those conditions.
- Restore sub-surface interflow to maintain hydrologic integrity.
- Maintain the proportion of rainwater entering a stream via each of 3 water balance pathways!
- Replicate the streamflow-duration pattern to mimic the Water Balance.
Try the Water Balance Model
Register a (free) “trial” account. As a trial account registrant you are free to access all model features