Na­ture of­fers the best de­fence against flood­ing

How T.O. should deal with ex­ces­sive rain­fall mov­ing for­ward

Midtown Post - - Life -

Spring flood­ing in Canada this year up­ended lives, in­un­dated city streets and swamped houses, prompt­ing calls for sand­bags, sea­walls and dikes to save com­mu­ni­ties. On­tario and Que­bec’s April rain­fall was dou­ble the 30-year av­er­age. Thou­sands of homes in 130 Que­bec mu­nic­i­pal­i­ties stretch­ing from the On­tario bor­der to the Gaspé Penin­sula flooded in May. The On­tario gov­ern­ment had to boost its re­sources for an emer­gency flood re­sponse, and the City of Toronto was forced to close the Toronto Is­lands.

In At­lantic Canada, some parts of New Bruns­wick recorded more than 150 mil­lime­tres of rain dur­ing a nearly 36-hour, non-stop down­pour. In B.C.’s Okana­gan, rapidly melt­ing snow­pack and swelling creeks caused lake lev­els to rise to record heights. The City of West Kelowna de­clared a state of emer­gency and evac­u­ated homes.

Floods have be­come one of the most vis­i­ble signs of the ef­fects of cli­mate change in cities, towns and ru­ral ar­eas through­out Canada. Spring floods aren’t un­usual, but the in­ten­sity and fre­quency of re­cent rains are break­ing records. The In­ter­gov­ern­men­tal Panel on Cli­mate Change an­tic­i­pates a sig­nif­i­cant in­crease in heavy pre­cip­i­ta­tion events and flood­ing in many parts of the world, in­clud­ing Canada. When tem­per­a­tures rise, the at­mos­phere car­ries more mois­ture, so when it rains, it dumps. The In­sur­ance Bu­reau of Canada found one in five Cana­di­ans faces some level of flood risk, and 1.8 mil­lion house­holds are at high risk.

With more than 80 sig­nif­i­cant floods in Canada since 2000, in­sur­ance costs are sky­rock­et­ing. Cana­di­ans per­son­ally shoul­der about $600 mil­lion each year in losses re­lated to flood­ing.

De­for­esta­tion, wet­land de­struc­tion and ar­ti­fi­cial shore­line projects worsen the prob­lem. In­sur­ance agen­cies rec­og­nize that, com­pared to ex­pen­sive in­fra­struc­ture, keep­ing ecosys­tems healthy pre­vents cli­mate dis­as­ters, saves money and im­proves re­siliency. In­sur­ers say con­serv­ing na­ture is about 30 times cheaper than build­ing sea­walls.

Still, many ju­ris­dic­tions fo­cus on en­gi­neered struc­tures, such as rock walls or even gi­ant sea gates for coastal flood­ing, dams and lev­ees to hold back rivers and drain­ing to pre­vent wet­lands from over­flow­ing. But built in­fra­struc­ture costs money and re­quires more main­te­nance than keep­ing nat­u­ral ar­eas in­tact.

Ur­ban con­crete and as­phalt sur­faces pre­vent wa­ter from in­fil­trat­ing into the ground and in­crease storm-wa­ter runoff. Na­ture ab­sorbs rain­fall and pre­vents ex­cess wa­ter from over­whelm­ing pipe net­works, back­ing up sew­ers and pool­ing in streets and base­ments.

Many lo­cal gov­ern­ments are try­ing to keep up by lim­it­ing de­vel­op­ment in flood zones, bet­ter manag­ing flood plains and up­dat­ing flood-man­age­ment sys­tems. The fed­eral gov­ern­ment has set aside $2 bil­lion to help lo­cal gov­ern­ments de­fend against nat­u­ral dis­as­ters like fire and flood­ing. It should al­lo­cate a sig­nif­i­cant por­tion to nat­u­ral in­fra­struc­ture so­lu­tions.

It’s time we rec­og­nized the im­por­tance of in­tact na­ture and built green in­fra­struc­ture as cen­tral to flood-pre­ven­tion ef­forts. Na­ture can help us — if we let it.

The flood­ing at Toronto’s Cen­tre Is­land

DAVID SUZUKI David Suzuki is the host of the CBC’s The Na­ture of Things and author of more than 30 books on ecol­ogy (with files from Theresa Beer).

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