Changes

Catastrophic losses from flooding have been steadily rising in Canada over the last two decades. The most common stormwater practices for mitigating riverine flooding are wet ponds and dry ponds, typically located at the end of the urban drainage system near streams.  LIDs are traditionally designed to manage more frequent and lower magnitude rain events.  However, as mentioned above, larger storm chambers, trenches and even bioretention can be designed with large temporary storage volumes to provide flood control functions similar to wet or dry ponds.   

Catastrophic losses from flooding have been steadily rising in Canada over the last two decades. The most common stormwater practices for mitigating riverine flooding are wet ponds and dry ponds, typically located at the end of the urban drainage system near streams.  LIDs are traditionally designed to manage more frequent and lower magnitude rain events.  However, as mentioned above, larger storm chambers, trenches and even bioretention can be designed with large temporary storage volumes to provide flood control functions similar to wet or dry ponds.   

In order to protect downstream properties from flood increases due to upstream development, CVC and TRCA have established flood control targets (2012 Stormwater Management Criteria Document) for future SWM planning through the process of updating of  Hydrologic Studies and Subwatershed-level Stormwater Management Studies that characterize flood flow rates, define the location and extent of Flood Damage Centers and assess the potential impact of further urbanization.

The most common stormwater practices for mitigating riverine flooding are wet ponds and dry ponds, typically located at the end of the urban drainage system near streams. LIDs are traditionally designed to manage more frequent and lower magnitude rain events. However, as mentioned above, larger storm chambers, [[infiltration trench|trenches]] and even [[bioretention]] can be designed with large temporary storage volumes to provide flood control functions similar to wet or [[dry ponds]].

Examples of SWM practices that can be applied to provide stormwater quantity control include:

In order to protect downstream properties from flooding due to upstream development, Conservation Authorities  establish flood control for future SWM planning through regularly updated of Hydrologic Studies and Subwatershed-level Stormwater Management Studies that characterize flood flow rates, define the location and extent of Flood Damage Centers and assess the potential impact of further urbanization.

*[[infiltration]] facilities and other low impact development practices with quantity control component.

Infiltration facilities and low impact development practices (such as [[bioretention]] and [[rainwater harvesting]]) are typically designed to manage more frequent and lower magnitude rainfall events. However, should these practices be designed for year round functionality, with sufficient flood storage capacity, the volume reductions associated with these practices will be recognized where the local municipality has endorsed the use of these practices and has considered long term operations and maintenance.

Infiltration facilities and low impact development practices (such as [[bioretention]] and [[rainwater harvesting]]) are typically designed to manage more frequent and lower magnitude rainfall events. However, should these practices be designed for year round functionality, with sufficient flood storage capacity, the volume reductions associated with these practices will be recognized where the local municipality has endorsed the use of these practices and has considered long term operations and maintenance.