Variable climate | Land planner says some decisions will be difficult and must involve all levels of government and the public
Brad Stelfox was travelling on the Danube River studying the effects of flooding in Europe when he received a phone call from his son in Calgary June 20.
The police had given him 10 minutes to evacuate the family home in Sunnyside, an inner city Calgary community hard hit by flooding.
The flooding of the Bow and Elbow rivers in southern Alberta was an extreme event that has resulted in an estimated $5 billion worth of damage. Scientists such as Stelfox, a land planner, and geographer Tom Johnston of the University of Lethbridge are starting to speak out about the necessity for future flood planning and a new approach to land development plans for Alberta.
Past scientific models have predicted a catastrophe of the size that hit southern Alberta this June, and past government studies have recommended flood proofing. More than 100 to 220 millimetres of rain hit the region in about 36 hours, and normally quiet rivers could not hold the surge of water that swept across the landscape.
“There hasn’t been as much appetite for people to present these climate change scenarios because they have been viewed as being unbelievable,” Stelfox said.
Scientists know the prairie climate has experienced extreme variability for centuries, and the last 100 years have been relatively gentle without much change. Looking back at weather history has found that ex-treme weather was normal.
“This event may encourage society and policy-makers to be a little bit more open minded to what some people have been saying for a long time and that is, variation is the norm,” he said.
The province has already promised new legislation to tighten building codes and implement flood protection strategies.
Johnston said some of those decisions may be difficult, but they must involve all levels of government and the public.
“It is very important to involve local communities in these planning exercises,” he said. “If you don’t, then the chances of buy-in are limited. On the other hand, local knowledge also needs to be complemented with the knowledge we derive from our scientific models.”
Buildings can be flood proofed and construction can be limited on flood plains, but Johnston said Alberta development regulations are written permissively. It may be time for province-wide standards rather than municipal approvals that vary between jurisdictions.
“It might be time to consider having those regulations written more directively to actually require those people who wish to develop in a known risky area to indicate what they are going to do to mitigate those risks,” he said.
The government recently introduced a flood hazard mitigation plan, which Johnston said will help increase public awareness about flood-affected areas.
He said this most recent flood should be seen as an extremely rare event. It is referred to as a once in a century flood, but that really means there is a one percent probability of a similar event occurring in any given year.
“It is a wake-up call,” Johnston said.
“There is lots of reason to believe that these kinds of events, perhaps not as extreme as this one, but these kinds of events are going to occur with greater frequency in the future and become increasingly severe whether we are talking about floods or droughts.”
Flood plain maps need to be updated regularly as the climate continues to change.
There are multiple flood plains within a watershed. The system is highly integrated and behaves like a row of dominoes, in which a change such as large-scale logging or in-creased paving can alter the hydrologic response profile.
Flash floods occur if a drainage basin cannot absorb the incoming water.
“As we continue to develop the upper reaches of these basins, we modify this hydrologic response, so the hazard mapping almost needs to be done on an ongoing basis.”
Land use affects how water moves, but it did not have much impact in this most recent event, said Stelfox, who is part of the Alces Group in Calgary, a private environmental and land planning company.
“From the systems I have looked at, it would be unfair to say that land use in terms of what we see in Alberta was directly responsible for its magnitude in the Bow, Ghost or the Highwood (rivers),” he said.
These are busy landscapes and have been influenced by rural residential areas, transportation corridors and forestry, but areas with less development were also hard hit.
“The bigger, broader picture seems to be that Mother Nature can be quite aggressive and violent and produced a large storm event,” he said.
Water was less able to infiltrate and enter the ground water system in some areas with more development, which resulted in faster runoff.
Stelfox’s company develops models on how future development with homes, roads and industrial activity affects a landscape. It is also consulting with government on what changes may be needed.
“If we don’t change our patterns and we continue to grow in human population infrastructure, then our maps show we are going to put an awful lot more infrastructure directly proximal to main stem rivers,” he said.
This includes the small tributaries that also flooded in June and caused considerable damage.
The province has also been developing regional plans with the most recent being the South Saskatchewan River Basin. It is designed around managing water resources, allocating water to various uses and maintaining a minimum flow for ecological and industrial uses rather than addressing flood hazards.
There was some reticence to push the flood issue.
“It’s in people’s minds, and people are probably directly asking how the South Saskatchewan regional plan is addressing variation in climate and are we putting the right things in the right places to mitigate these risks,” said Stelfox.
A provincial flood risk strategy was studied in a report issued in November 2006.
The report, which was led by George Groeneveld, former MLA for the Highwood constituency that includes High River, came up with 18 recommendations.
A report was also written in 2002, which the Groeneveld report cited as still being relevant.
Most of the recommendations urged improved updating of flood maps for rural and urban regions.
It also recommended addressing future development in flood prone areas and informing potential buyers of the risk of flooding. Alberta Environment was encouraged to collect more high water data on lakes and rivers as well as make historical flood information available on its website.
The Groeneveld report calculated that the recommendations would cost $306 million to implement incrementally.
- The government pledged $1 billion in initial funding to respond to the flooding emergency.
- Almost $70 million in immediate support has been distributed as pre-loaded debit cards to Albertans forced from their homes. Almost $48 million was provided within the first five days of the program’s launch.
- The province committed $50 million directly to High River, which was the worst hit community.
- In High River, 831 home inspections have been completed. Of the 452 inspected homes that will need to be significantly repaired or rebuilt, 364 have been fully assessed and 59 have been remediated.
- Almost 2,700 Albertans are still out of their homes living in temporary neighborhoods, hotels and with friends and family.
- More than 8,000 applications for Disaster Recovery support are already being processed, with 1,400 payments totaling nearly $7 million already made.
- Of the 8,000 applications for Disaster Recovery, 1,000 are being processed for small businesses.
- Fifty-three modular classrooms are under construction to replace schools that cannot reopen.
- More than 830 kilometres of provincial roads affected by flooding have reopened.
- The government has committed $20 million to restore land damaged by erosion.