Changes

==Strategies==

==Strategies==

[[File:Western beaches storage tunnel.jpg|300px|thumb|right|Construction of Western Beaches Storage Tunnel in Toronto (McNally, 2017) <ref name=McNally></ref>.]]

[[File:Western beaches storage tunnel.jpg|300px|thumb|right|The 4km long West Beaches Storage Tunnel in Toronto stores and treats combined sewer overflows and stormwater to prevent untreated sewage from entering Lake Ontario. It an grey infrastructure solution which helps prevent localized flooding by collecting and storing water and uses [[sedimentation]] and UV disinfection to improve water quality (McNally, 2017) <ref>McNally. 2017. Western Beaches Tunnel – Toronto, ON. http://mcnally.ca/tunneling-projects/western-beaches-tunnel-toronto/#:~:text=Project%20Outline,pump%20station%20at%20Strachan%20Avenue.</ref>Construction of Western Beaches Storage Tunnel in Toronto (McNally, 2017) <ref name=McNally></ref>.]]

[[File:FEMA P-259 Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures Structure protected by levee and floodwall 520px (1).png|300px|thumb|right|Floodwall and levee protects building from flood water (Reduce Flood Risk, 2022)<ref>Reduce Flood Risk. 2022. Construct a floodwall barrier. https://www.reducefloodrisk.org/mitigation/construct-a-floodwall-barrier/</ref>.]]

[[File:FEMA P-259 Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures Structure protected by levee and floodwall 520px (1).png|300px|thumb|right|Floodwall and levee protects building from flood water (Reduce Flood Risk, 2022)<ref>Reduce Flood Risk. 2022. Construct a floodwall barrier. https://www.reducefloodrisk.org/mitigation/construct-a-floodwall-barrier/</ref>.]]

Effective flood mitigation strategies include both grey infrastructure (traditional engineered solutions), green infrastructure (nature-based solutions), and grey-green hybrids.

 

Effective flood mitigation strategies fall into three categories: grey infrastructure (traditional engineered solutions), green infrastructure (nature-based solutions), and grey-green hybrids. Cities typically combine measures based on local flood risks, scale, and desired co-benefits such as water quality improvement and urban cooling.

 

===Grey infrastructure solutions===

===Grey infrastructure solutions===

*'''[[Wet ponds|Detention ponds and stormwater basins]]''' store excess runoff and release it gradually.

 

*'''Underground stormwater storage''' can help prevents sewer overflows. For example, the 4km long West Beaches Storage Tunnel in Toronto stores and treats combined sewer overflows and stormwater to prevent untreated sewage from entering Lake Ontario. It helps prevent localized flooding by collecting and storing water and uses [[sedimentation]] and UV disinfection to improve water quality (McNally, 2017) <ref name=McNally>McNally. 2017. Western Beaches Tunnel – Toronto, ON. http://mcnally.ca/tunneling-projects/western-beaches-tunnel-toronto/#:~:text=Project%20Outline,pump%20station%20at%20Strachan%20Avenue.</ref>.

*'''Levees and floodwalls''' are most often used to protect against riverine and coastal flooding, and can also be used around buildings to protect from surface flooding.

| [[Wet ponds|Detention ponds & stormwater basins]]

| Store excess runoff, release gradually

| Underground stormwater storage

| Prevents sewer overflows, reduces localized flooding

| Can integrate water treatment (e.g., Toronto’s Western Beaches Storage Tunnel)

|-

| Levees & floodwalls

| Protect against riverine/coastal flooding; also used around buildings for surface flooding

===Green infrastructure solutions===

===Green infrastructure solutions===

{|class="wikitable"  

{| class="wikitable"

! Practice

!style="background: darkcyan; color: white"|LID Practice

! Flood Mitigation

!style="background: darkcyan; color: white"|Flood Mitigation

|-

|-

|[[Bioretention]]

| [[Bioretention]]

|

| Reduces peak flow, increases infiltration

Reduce peak stormwater flow and increases infiltration.

|-

|-

|[[Permeable Pavements]]

| [[Permeable pavements]]

|

| Allows infiltration, reduces runoff

Allows water to seep into the ground, reducing runoff.

|-

|-

|[[Green Roofs]]

| [[Green roofs]]

|

| Absorb rainfall, delay runoff

Absorb rainfall and delays runoff into drainage systems.

|-

|-

|Riparian Buffers

| Riparian buffers

|

| Protect banks, reduce erosion

Protect streambanks and reduces erosion.

|-

|-

|[[Constructed Wetlands]]

| [[Wetlands|Constructed wetlands]]

|

| Retain/filter stormwater

Retain and filters stormwater while providing habitat.

|-

|-

|[[Rainwater harvesting]]

| [[Rainwater harvesting]]

|

| Collects precipitation, reduces runoff

Collects precipitation in tanks to reduce surface runoff.

|-

|-

|[[Rain gardens]]

| [[Rain gardens]]

|

| Reduces on-site runoff

Reduces stormwater runoff and conserves water on site.

|}

|}