El Nino raises flooding fears: study

Climatic events linked to flooding and erosion of low-lying coastal areas

A new climate study is forecasting the potential for extreme flooding and coastal erosion that could affect waterfront properties on the Saanich Peninsula and along the entire west coast of North America. Researchers from the University of Victoria and 12 other institutions analyzed wave, water levels and shoreline response data to uncover links between flooding and erosion and climatic events such as El Niño and La Niña.

This winter is shaping up as a “monster” El Niño year, in which warmer waters in the Pacific can cause the northwest coast of the continent to experience warmer, drier winters.

“We’ve seen 40 to 70 or more centimetres of extra water, superimposed on the tide for several months during past El Niños so we can expect to see that as well this year,” said Ian Walker, professor of geography at UVic, explaining that could mean flooding, coastal erosion and higher tides to low-lying areas along the coast.

“Generally, it means the ocean levels are higher because warm things expand so, with higher water levels then, the same storm, the typical winter storm that we see every year, could have a greater impact in terms of coastal erosion and flooding because it hits the beach at a higher elevation.”

On the Peninsula, low lying sandy beaches such as Island View, Cordova Spit and the stretch along Cadboro Bay by the low bluffs could be areas more several affected this winter.

“In a season like this, where we have our normal tides and even normal storms … these will have a higher impact on the beach. In terms of erosion management and flood potential, there’s a greater potential this year for those reasons,” said Walker, coauthor of the study published Monday in Nature Geoscience.

Walker noted that the findings apply to future climatic events, including La Niña, which can cause wetter than normal winters.

“It’s not just El Niño we should be concerned about,” he stated. “Our research shows that severe coastal erosion and flooding can occur along the B.C. coast during both El Niño and La Niña storm seasons, unlike further south in California. We need to prepare not only for this winter, but also for what could follow when La Niña comes.”

Walker’s research has taken him from Haida Gwaii to California and the data is based on analysis of about 40 different sites since the early 2000s.