Flooding inevitable if building beside Okanagan waterways: fisheries biologist

Water forum speaks to challenges extreme weather is having on fish and farms

The return of the sockeye salmon to the Okanagan Valley watershed is the result of an initiative by the Okanagan Nation Alliance to restore the spawning channel capabilities of the Okanagan River. (File photo)

What offers “delicious opportunities” for land development will only prove to be significant headaches for Okanagan community planners trying to mitigate against extreme weather events, says a fisheries biologist with the Okanagan Nation Alliance.

Kari Alex says following the pathway of recent decades to remove existing natural vegetation from floodplains and develop next to rivers and creeks in the Okanagan Valley watershed will lead to one inevitability – flooding.

“We have created our own problem, building along creeks and rivers and building dikes, we have reduced our capacity of resiliency to climate change,” said Alex.

“It’s not what people want to hear but there are not a lot of engineering solutions left. We need to increase the building setback required from rivers and creeks.”

Alex made the comments while speaking about the ONA efforts to revitalize the salmon fishery on Okanagan River as a guest panelist at a water forum held Wednesday (March 16), organized by the Okanagan Basin Water Board WaterWise initiative, a community outreach and education program, in recognition of UN World Water Day on March 22.

Alex said the salmon fishery restoration efforts have found success through mitigation efforts to allow the natural flow of the Okanagan River to spread out.

“For fish, areas of the river where there is diking, rip rap or engineered channelization, there are either no or reduced numbers of fish,” she said.

Alex said areas of the river where floodplain setback and re-establishment of natural back channels has occurred through the ONA’s habitat restoration efforts, the salmon population has begun to thrive again.

“The mistake we are making now is we will seriously impact ourselves if we don’t setback ourselves from the river banks,” she said.

“If we continue to build houses too close then all those spaces are at risk. The rivers will run right through it whether you want it to or not.”

She said floodplain areas sustained and mitigated in their natural states not only helps enhance fish habitat, but neutralizes the threat of flooding.

Floodplain cottonwood trees serve as massive hollow sponges that soak up excessive water and re-release it throughout the summer.

Prior to diking and channelization, that was how floodplains were able to mitigate water flows above and below the ground, as groundwater flows absorbed excessive water and recirculated it through vegetation to avoid excessive ground saturation, said Alex.

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Also speaking at the forum was Kirsten Hannam, an agrologist with the Agriculture and Agri-Food Canada’s Summerland Research and Development Centre, talking about what farmers are experiencing and what is being done to help them prepare and meet the challenges of food security posed by climate change.

Hannam said excessive heat remains a nemesis for farmers, as weather records show the number of 35 Celsius days in summer has increased steadily in the past 100 years, with last summer the highest number recorded ever.

She said for farmers, that translates into higher evapotranspiration levels for tree fruit crops, which reflects how much water is lost on the soil surface transported from plant leaves to the ground in a day.

“An apple tree acts like a crazy straw. At one end are the tree roots in the soil which suck up the water into the tree system and the water flows out from droplet holes in the tree leaves,” she said.

Hannam said the heat dome conditions last summer took a toll on fruit crops, overheating cherries until they became sun-dried, causing sunburn damage to apples causing them to prematurely fall off the trees or were unmarketable for sale.

She noted while irrigation remains an effective counter-balance to drought conditions when carefully scheduled and the soil moisture is carefully monitored, in serious drought years that places increasing pressure on water inventory to draw from.

“The heat dome event also showed us other avenues to pursue, such as using water to produce a healthy dry row of grass between tree fruit rows which orchardists were telling us appeared to help cool the orchard and protect the fruit from excessive heat damage,” Hannam said.

She noted orchardists in Oregon and Washington are also working with an overhead cooling or fogging system to protect fruit crops from heat damage.

“We are also looking at other ways to reduce the need for water such as surface mulch, foliar sprays, shade nets and orchard architecture to protect fruit from sun damage,” she said.

Climate change