Land use regulations needed to reduce flood risks: experts

Planners want development restricted on flood plains and high-risk areas

Southern Albertans responded well to last year’s flood crisis, but the recovery is going to take years, said Calgary mayor Naheed Nenshi.

More than 100,000 people were affected in 30 communities when homes and businesses went under water June 19-21. The final costs are expected to exceed $6 billion, making it Canada’s most expensive natural disaster.

Nenshi said better forecasting would give people more time to protect themselves and their property.

Meanwhile, work continues on repairing infrastructure and developing control strategies such as dikes, berms and water diversion tunnels. Some projects may not be finished until 2020.

“We are not anticipating any super high water events this spring based on snow pack and the weather patterns, but we don’t know that,” Nenshi told the Canadian Water Re-sources Association annual meeting held in Calgary March 24-25.

Some town planners want a stronger provincial land use plan for building on flood plains. The information should be included on land titles so home buyers know if the property is in a floodplain or in a sour gas emergency evacuation zone.

Frank Frigo of Calgary’s infrastructure planning department said managing floods in the Bow River basin is difficult because of the concentrated population and heavy development. Much of the development in risky areas was built before the implications were fully understood.

He said modern land use restrictions are better at dealing with new development but they are less effective in dealing with what is already there.

Downtown Calgary is a river valley with ground water streams running parallel to the Elbow and Bow rivers. Ground water surges and floods basements during heavy rainfalls.

Similar problems exist in Canmore, where demand is high for scenic properties that are sometimes built on flood prone areas, said town planner Andy Esarte.

Canmore developments such as Cougar Creek were built on flood prone areas and others are proposed. However, Esarte said some may not go ahead as the risk is re-evaluated.

The aftermath of the flood left as much as nine metres of silt and debris in places. The town suffered $50 million in direct damage.

Canmore’s woes were partly attributed to the effect of hundreds of mountain creeks, which carry as much debris as water. Creek banks had been armoured beforehand but did not hold.

Calgary deputy fire chief Tom Sampson said the fallout from the flood continues today.

“We have ongoing problems that we still don’t have solutions to,” he said.

As well, High River remains in recovery mode with some people still out of their homes.

The disaster caused $83 million in damages. New dikes are planned and are expected to be built a metre higher than levels projected for the next once in a 100 year flood. As well, roads will be elevated and one community will be demolished.

In addition, new flood plain maps are being developed, and new engineering reports are underway for the Bow, Elbow, Highwood, South Sask-atchewan and Sheep rivers.

As well, community consultations will be held to discuss a Highwood River diversion, an Elbow River dry dam and a Calgary tunnel to divert water.