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Line 123: − + − [[File:2022-01-18-severe-weather-2021-21-billion-damage-image2.jpeg|thumb|500px|The above chart shows insurable losses each year caused by natural disasters, the most costly of these being flooding, as reported by the Insurance Bureau of Canada in 2022. ''“In today's world of extreme weather events, the new normal for yearly insured catastrophic losses in Canada has become $2 billion, most of it due to water-related damage. Compare this to the period between 1983 and 2008, when Canadian insurers averaged only $422 million a year in severe weather-related losses."'' (IBC, 2022).<ref>Insurance Bureau of Canada (IBC). 2022. Severe Weather in 2021 Caused $2.1 Billion in Insured Damage." News & Insights. Accessed: https://www.ibc.ca/news-insights/news/severe-weather-in-2021-caused-2-1-billion-in-insured-damage</ref>.]] − <br> − − ''“Hydrological changes associated with urbanisation are increased storm runoff volumes and peak flows (Qp), faster flow velocities and shorter time of concentrations. A reduction in infiltration generally leads to less groundwater recharge and baseflow.The flashy response results in tremendous stresses for the urban stream and downstream receiving areas (Walsh et al., 2005)."'' − − 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. − − 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]]. − − 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. −
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==Introduction==
==Introduction==
Flooding is a major environmental and economic challenge, particularly in urban areas where impervious surfaces prevent natural infiltration. Flooding can result in traffic interruption, economic loss, infrastructure damage, basement flooding and other undesirable consequences. [[Climate change]] is increasing the frequency and intensity of extreme rainfall events, exacerbating flood risks. This will be particularly severe in older areas where the minor system was not designed to today’s standards and/or major drainage system pathways have been altered or do not exist. Flood mitigation strategies that incorporate Low Impact Development (LID), traditional stormwater management, and hybrid infrastructure can manage stormwater effectively and reduce flood impacts.
[[File:2022-01-18-severe-weather-2021-21-billion-damage-image2.jpeg|thumb|500px|The above chart shows insurable losses each year caused by natural disasters, the most costly of these being flooding, as reported by the Insurance Bureau of Canada in 2022. ''“In today's world of extreme weather events, the new normal for yearly insured catastrophic losses in Canada has become $2 billion, most of it due to water-related damage. Compare this to the period between 1983 and 2008, when Canadian insurers averaged only $422 million a year in severe weather-related losses."'' (IBC, 2022).<ref>Insurance Bureau of Canada (IBC). 2022. Severe Weather in 2021 Caused $2.1 Billion in Insured Damage." News & Insights. Accessed: https://www.ibc.ca/news-insights/news/severe-weather-in-2021-caused-2-1-billion-in-insured-damage</ref>.]]
Flooding is a major environmental and economic challenge, particularly in urban areas where impervious surfaces prevent natural infiltration. Flooding can result in traffic interruption, economic loss, infrastructure damage, basement flooding and other undesirable consequences. [[Climate change]] is increasing the frequency and intensity of extreme rainfall events, exacerbating flood risks. This will be particularly severe in older areas where the minor system was not designed to today’s standards and/or major drainage system pathways have been altered or do not exist. Catastrophic losses from flooding have been steadily rising in Canada over the last two decades.
''“Hydrological changes associated with urbanisation are increased storm runoff volumes and peak flows (Qp), faster flow velocities and shorter time of concentrations. A reduction in infiltration generally leads to less groundwater recharge and baseflow.The flashy response results in tremendous stresses for the urban stream and downstream receiving areas (Walsh et al., 2005)."''
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. Flood mitigation strategies that incorporate Low Impact Development (LID), traditional stormwater management, and hybrid infrastructure can manage stormwater effectively and reduce flood impacts.
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==Riverine Flooding==
==Riverine Flooding==
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, 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]].
==Modelling Flood Mitigation Potential of Conventional LIDs==
==Modelling Flood Mitigation Potential of Conventional LIDs==