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Line 1: − [[File:Screenshot 2025-09-19 115121.png|400px|thumb|right|"Coastal flooding" on Toronto Islands in 2017. Image Credit: Toronto Life (2017) <ref>Toronto Life. 2017. Flooding on the Toronto Islands is terrible—but also weirdly beautiful. https://torontolife.com/life/flooding-toronto-islands-terrible-also-weirdly-beautiful/</ref>]] − + − + − + − + − + − + − + − + − + + − + + − + − + − + − + − + − + − + − + − + +
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==Introduction==
==Introduction==
Flooding is a major environmental and economic challenge, particularly in urban areas where impervious surfaces prevent natural infiltration. [[Climate change]] is increasing the frequency and intensity of extreme rainfall events, exacerbating flood risks. Flood mitigation strategies that incorporate Low Impact Development (LID), traditional stormwater management, and hybrid infrastructure can manage stormwater effectively and reduce flood impacts.
Flooding is a major environmental and economic challenge, particularly in urban areas where impervious surfaces prevent natural infiltration. [[Climate change]] is increasing the frequency and intensity of extreme rainfall events, exacerbating flood risks. Flood mitigation strategies that incorporate Low Impact Development (LID), traditional stormwater management, and hybrid infrastructure can manage stormwater effectively and reduce flood impacts.
{|class="wikitable"
{|class="wikitable"
|+ Types of Flooding
|+ Types of Flooding
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|-
!Pluvial (surface) flooding
! Pluvial (surface) flooding
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| [[File:Pluvial_flooding_example.jpg|200px]]
*Caused by extreme rainfall exceeding soil infiltration and storm sewer capacity.
|
*Common in urban areas with high impervious surface coverage.
* Caused by extreme rainfall exceeding soil infiltration and storm sewer capacity.
*Exacerbated by poor drainage and outdated stormwater infrastructure.
* Common in urban areas with high impervious surface coverage.
*"Flash flooding" is when intense rainfall overwhelms drainage systems, leading to sudden surface flooding. This can be common in dense urban environments where water cannot infiltrate quickly.
* Exacerbated by poor drainage and outdated stormwater infrastructure.
* "Flash flooding" is when intense rainfall overwhelms drainage systems, leading to sudden surface flooding. This can be common in dense urban environments where water cannot infiltrate quickly.
|-
|-
!Fluvial (riverine) flooding
! Fluvial (riverine) flooding
| [[File:Screenshot 2025-09-22 100405.png|300px|thumb|right|Don Valley Parkway (City News, 2024)<ref>City News. 2024. From the scene: Don Valley River floods section of DVP, stranding drivers. https://www.youtube.com/watch?v=fbyaYZy0d0A&t=68s</ref>]]
|
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*Occurs when rivers overflow their banks due to heavy rainfall or snowmelt.
* Occurs when rivers overflow their banks due to heavy rainfall or snowmelt.
*Worsened by upstream land use changes that increase runoff.
* Worsened by upstream land use changes that increase runoff.
*"Flash flooding" may occur in steep river catchments, where rapid runoff accumulation causes sudden rises in water levels.
* "Flash flooding" may occur in steep river catchments, where rapid runoff accumulation causes sudden rises in water levels.
|-
|-
!Coastal (shoreline) flooding
! Coastal (shoreline) flooding
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|[[File:Screenshot 2025-09-19 115121.png|300px|thumb|right|Toronto Island (Toronto Life, 2017)<ref>Toronto Life. 2017. Flooding on the Toronto Islands is terrible—but also weirdly beautiful. https://torontolife.com/life/flooding-toronto-islands-terrible-also-weirdly-beautiful/</ref>]]
*Driven by storm surges, and/or lake-level rise.
|
*More common in areas with poor shoreline protection.
* Driven by storm surges, and/or lake-level rise.
*"Flash flooding" is less common, but can occur when extreme rainfall occurs throughout the watershed.
* More common in areas with poor shoreline protection.
|}
* "Flash flooding" is less common, but can occur when extreme rainfall occurs throughout the watershed.
|}
==Strategies==
==Strategies==