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A change in the weather

Shifting rainfall patterns demand costly measures
By Mike Youds
July 25, 2015 3:14 P.M.
Traffic backed up following June's deluge in Westsyde.

The City is taking a closer look at the long-term implications of climate change and storm surges as it develops watershed master plans to .

Council recently awarded a $179,000 contract to Urban Systems to deliver plans for Guerin and Peterson creeks, which have been on the City’s action list for a number of years. 

When a citywide stormwater management plan was adopted in 2009, it identified a need for 12 master plans for watersheds within municipal boundaries. Five of those were considered priorities, of which two have been completed for the North Shore and Batchelor Heights. 

After last summer’s record-setting deluge, which caused havoc when it swept through the city, Peterson and Guerin creeks were bumped up to the top of the list. Valleyview ranks No. 5 and is next in line.

The rainstorm dropped 20 millimetres of precipitation on the city in 25 minutes, creating flash flooding that overwhelmed stormwater systems, turning streets into flood channels. 

Resulting damage to City infrastructure cost was estimated to amount several million dollars. 

A boy had to be rescued from the Thompson River and thousands of homes were left without power. City crews were overwhelmed by the event.

Mayor Peter Milobar has referred to that storm as a once-in-a-century event, although dramatic changes in weather patterns are rewriting long-term projections. Westsyde sustained the brunt of the damage from a rain and hail storm on June 30, resulting in the evacuation of 60 homes and a cleanup bill expected to cost taxpayers as much as $750,000. The cost to individual homeowners would push the total price tag of the brief storm to well over $1 million. 

And as the City comes to terms with the increased cost of higher-capacity stormwater systems, homeowners also have to consider new measures to protect their homes from overland flooding.

New watershed plans are intended to pinpoint flood mitigation measures and infrastructure improvements that would reduce property damage in such storms, said Jonathan Welke, the City’s water and sewer engineer.

“We want to take a more holistic approach and look at all request for services after last year’s storm,” he told council recently.

Part of the planning will involve analysis of research by the Pacific Climate Impacts Consortium, a climate service centre at the University of Victoria. The consortium notes in its online course Climate Change 101 that Kamloops has undergone greater variability in its climate over the long term relative to other cities, specifically Victoria.

“We’re going to be looking at the latest research done on our area,” Welke explained.

Last summer’s rainstorm damaged tributary channels feeding Peterson Creek, but the main channel held up very well, Welke said.

The 10th Avenue underpass was flooded by the storm and the plans will look at that problem, but there are probably areas where the risk of property damage is much higher, he said. 

Cost-benefit analysis will be used to determine what measures the City would tackle initially.

A climate change information package produced by the City of Kamloops can be found at

The plan states that increased intensity of storms, mountain pine beetle infestation and increased forest fire activity are part of a pattern that has altered Kamloops’ climate over the past century.

Ensuring hazardous conditions don’t threaten public safety or damage property is but one of the recommendations contained in the plan. Others include:

• Continuing to implement a community wildfire protection plan.

• Doubling community gardens by 2020.

• Increasing active farms in the area.

• Promoting local food security.

TRU geographer ‘leverages ubiquity’

A system is only as good as the data on which it is based, a fact brought home in costly, destructive and sometimes dangerous ways by ill-equipped stormwater systems.

A system designed in 2015, obviously, won’t be the same as those built in Kamloops 30 or more years ago.

TRU geographer David Hill hopes to come up with better data so that cities such as Kamloops can design better long-term stormwater management in the face of climate change.

“We have a lot of quantity issues — scarcity or excess,” Hill noted when asked to outline his study. “Certainly we saw the excess (with June's storms).”

Hill’s study, entitled Leveraging Ubiquity: A Big Data Approach to Environmental Observation, was one of five TRU research project recently awarded grants from the National Sciences and Engineering Research Council.

His five-year study, just getting underway, is looking at an emerging consensus for measuring rainfall and other precipitation at a higher resolution than possible with conventional weather observation. It’s called a data fusion model. By gathering non-conventional data from sources such as irrigation monitoring, transit buses and observant “citizen scientists” using smartphone apps, Hill aims to develop more accurate weather forecasting.

A key challenge of managing climate change is that the old models may no longer apply. A more dynamic model is needed so that urban infrastructure can be adapted to handle the changes.

Kamloops offers some advantages as a location for Hill’s research. 

First, it is a manageable size relative to a metropolis such as Vancouver. Second, it is semi-arid and subject to overland flows, the sort that swept through Oak Hills on June 30 and Sun Rivers last July 23. Third, the city’s valley bottom location and micro-climate variables mean weather radar is not particularly reliable.

While qualitative data gathered from the public through sources such as apps may lack the scientific precision of historic weather data, yet it still has value when combine in aggregate form with data from ubiquitous sources, he suggested.  

Emergency services respond to the June 30 storm.

Storm brought 20 mm in 30 minutes

The old proverb “It never rains but pours,” comes from England but it could just as easily sum up summer weather in Kamloops.

Intense rainstorms in early summer are nothing out of the ordinary here, but recently their intensity seems to have exceeded any torrential downpour in memory. Combined with hail and high winds, more rain falls in a single location than can be accommodated by the storm sewers. Chaos results.

First there was the storm that brought 20 mm in 20 minutes (and then some) in July 2014. Now history has recorded the June 29 and 30 storms that brought 20 mm in 30 minutes.

“They were very similar situations in terms of rainfall intensity,” said Lisa Coldwells, Environment Canada meteorologist.

The June 29 storm entered the city over the airport with winds of up to 91 km/h.

“Those aren’t hurricane-force, but they’re very strong winds.”

On June 30, the storm descended north of the airport with winds of 72 km/h.

“I would call it a quick-moving storm that moved in and went right across the city in half an hour,” she said. Last year’s big rainstorm, in comparison, rolled in over Sun Rivers and sat there for hours.

Overall, June brought 82.5 mm of rainfall, slightly more than the average of 71 mm. The month stands out more due to its warmth with numerous daily records set across the province. It was the fifth hottest June in Kamloops since record keeping began in 1891.

Climate changes observed and forecast

The Pacific Climate Impacts Consortium (PCIC) notes the following changes in climate in the Kamloops region over the last 100 years: 

• Average minimum temperature trend has increased 1.0–1.5 C

• Average mean temperature trend has increased 1.0–1.5 C

• Winter minimum temperature trend has increased 2.5 C

• Winter maximum temperature trend has increased 1.5–2 C

• Monitoring at nearby Heffley Lake indicates that over the last 50 years, the lake has frozen later in the year and started to break-up earlier in the year

• Snow packs at April 1 are decreasing in size over the last 50 years

Looking forward, the PCIC predicts the following for the Thompson Nicola1 area by 2050:

• Mean temperatures will have risen 2.5 C

• Annual precipitation will increase by 10 percent

• Mean temperatures in January could increase by 3.6 C and 3 C in July

Precipitation amounts are expected to increase by eight percent in January and decrease by three percent in July

— From the Sustainable Kamloops Plan information package on climate change


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