More than the climate crisis was behind last November’s rising waters, death and destruction; experts urge province to make course correction.
The catastrophic flooding in Merritt in November 2021 occurred after a rainfall similar to previous precipitation events that didn’t cause flooding. The difference? Professional hydrologists implicate logging, forest fires and snowpack in the nearby Coldwater River watershed.
WHEN PREMIER JOHN HORGAN declared a provincial state of emergency in the wake of last November’s horrific floods, landslides and deaths, he was quick to name the culprit.
The “never seen before” flooding in southern British Columbia was a direct result of “human-caused climate change,” he said, adding that such floods were “increasing in regularity” thanks to our unceasing use of fossil fuels.
But climate change alone didn’t account for the numerous highway washouts, the lethal landslide that killed five on the Duffey Lake Road, the thousands of people displaced from their damaged or destroyed homes, the dikes and sewage treatment plants overwhelmed by the rising waters, and more.
Other important factors combined to turn last November’s deluge into the monster it became.
Heavy two-day rainfalls similar to those of late last year have occurred in the past without triggering the horrendous damage witnessed in November 2021. Not one, but many things conspired to cause such destruction.
The essential public policy questions now are what lessons the government learns from last year’s events:
Are there things it can easily do now to more accurately anticipate what troubles lie ahead and therefore provide robust early warnings to vulnerable communities?
Can it better regulate industries known to play a role in increased flood frequencies, such as the logging industry?
And finally, what can it do to better incorporate knowledge about climate change-related events such as wildfires into flood forecasting models so that more timely and effective warnings can be given to communities that may be in harm’s way?
One person who has pondered such questions since November’s events is Allan Chapman. A long-time professional hydrologist, Chapman once headed BC’s River Forecast Centre, the critical front-line agency tasked with warning the public and vulnerable communities about flood risks.
He says the premier’s invocation of climate change and climate change alone “deflects accountability for failures within government.”
The potential for last year’s rains to trigger extensive flooding, particularly to lands damaged by wildfires, was foreseeable, Chapman believes, and had only a partial connection to climate change. Other factors like extensive logging and logging roads in key river valleys, or the accumulated snow in mountains that rapidly melted in the face of the rain, were both known risk factors that had nothing to do with climate change at all.
Given the prospects for increased flood severity due to wildfires and logging or the presence of snow in watersheds forecast to get a lot of rain, Chapman says flood forecasting and emergency planning staff in the provincial government had all the information they needed to issue early warnings to vulnerable communities about the potential for dangerous times ahead.
Chapman first publicly voiced concern about the government’s response to last November’s heavy rains a couple of weeks after the event after analyzing the forecast centre’s actions in the lead-up to the floods. He said then that weather and streamflow data readily available to professional staff at the agency should have resulted in them making higher-level warnings far earlier than they did.
Since then, the provincial government has been named in a class action suit, in part for failing to adequately warn residents in the Sumas Prairie about the impending flooding, which resulted in thousands of farm animals being killed, some of the best farmland in the province being contaminated and farm buildings and machinery destroyed.
Chapman has since looked more closely at various data to try to make sense of what happened in mid-November. His review included rainfall data, water flow data in streams and rivers proximate to the flooding, snowpack data in key watersheds and significant land-use disturbances in the watersheds closest to where the flooding occurred.
He has detailed his findings in a 22-page report that he sent to provincial Ministry of Forests hydrologists. The River Forecast Centre is housed in the ministry that is responsible for ensuring the safety of dikes, for managing forest industry activities—including logging and road-building on public lands—and for dealing with wildfires.
Chapman also submitted a lengthy letter summarizing his findings to Forests Minister Katrine Conroy.
One of Chapman’s key findings is that the intense rains of last November were unquestionably large, but in keeping with other heavy rains of previous years.
What happened in November was, in many ways, a classic “pineapple express” or, as it is now more frequently called, an “atmospheric river.”
At some Environment Canada weather stations, including Abbotsford, Aggasiz and Hope, the rainfall recorded for a single day was a record. But the rainfall accumulations over the two days of the storm were not.
“Other major and similar storms appear in the record in October 2003, November 1990 and a few other years. The data lead to the conclusion that although the rainfall on November 14 and 15 was certainly large, it was not unprecedented and should not have been unanticipated” Chapman reported.
It is what was layered on top of all of the rain that became the issue.
A pineapple express delivers lots of rain simultaneously with warmer temperatures. If such events are preceded by snow accumulating in the mountains, that can be a big problem. During atmospheric river or pineapple express storms, temperatures warm and the freezing line rises as the storm front passes over. The warmth and rain turn much or all of the snow below the freezing line to water.
Chapman’s report looked at data from several “snow pillows” (sites where snow depths are measured) and weather stations operated by the BC government, and documented how the rapid melting of accumulated snow substantially augmented the rainfall water, increasing peak flows in key rivers.
He concluded that “the water contributed by snow melt” in the critical 48 hours beginning on November 13 and carrying through November 15 was half as much and possibly equal to all of the volume of rainfall at some measurement locations and was “a significant contributor to the severity of the river flooding,” particularly in the Merritt area.
This meant that on critical rivers such as the Tulameen, Nahatlatch and Sumas, peak water flows were in the range of what might be expected every 300 years.
But this was nothing compared to the peak flows on the Coldwater River. Based on water gauge readings on that river both at Brookmere and Merritt, Chapman found that the peak flows were “beyond extreme,” possibly reaching levels seen only once every 1,000 years.
Corresponding data for the Nicola River were not available in real time, Chapman noted. But by looking at readings from gauges in the nearby Coldwater, Chapman estimated that the Nicola’s peak flows were between 700 and 1,000 cubic metres per second—enough water to fill an Olympic-size swimming pool roughly every three seconds. That put the river’s peak flows at levels possibly 2.5 times higher than the previously highest recorded levels, based on 59 years of measurements.
“The rainfall was large, but not unexpectedly large based on the historical record,” Chapman says. “It was the rain on snow that proved to be so significant.”
And that, Chapman says, should not come as a surprise to anyone in the flood forecasting community. He explains that the historical data available show that “all the floods of record” in the Coldwater, Tulameen and Similkameen river valleys “result from October-January atmospheric river rain storms, and this combination of heavy rain and snowmelt. The November 13 to 15 storm, although extreme, should not be considered unusual in this regard. It is the standard flood-causing mechanism for these rivers.”
A burning issue
The “beyond extreme” water level on the Coldwater River was bad news for Merritt’s 7,000 residents. The town’s sewage treatment plant—like many such plants throughout BC—is on the floodplain.
In a cascade of events, the plant was overrun by floodwaters, its contaminated sewage then mixed with the floodwater which in turn contaminated groundwater wells used to supply local drinking water as well.
The evacuation of the town’s residents was inevitable under such circumstances.
Heavy rain on snow—a phenomenon well understood by hydrologists—elevated the severity of the floods. But it was not the only reason flooding was so severe.
Foresters and climate scientists know that temperatures are creeping up and more forests are becoming drier and susceptible to burning.
Mike Flannigan is an award-winning researcher and internationally recognized expert on wildfire behaviour who works at Thompson Rivers University where he is the new BC research chair in predictive services, emergency management and fire science.
He has long warned that wildfire seasons are starting earlier, extending later into the year and that BC along with Canada as a whole are witnessing “significant increases in the area experiencing high to extreme fire danger.” He would like to see the provincial and federal governments produce “risk maps” that clearly spell out where danger may be imminent due to wildfires and floods, especially for northern, more-remote rural communities, both Indigenous and non-Indigenous.
SparksGeo is a Prince George-based company whose geospatial analysts work with satellite data. In April, the company released a report suggesting a connection between the intense wildfires that burned in 2021 and subsequent flood-related destruction, particularly in the highway corridors where some of the most severe road damage occurred.
While it cautioned that “the causes of flood damage are complex and involve the interplay of many different environmental and engineering variables,” the company said the satellite imagery suggests a compelling correlation between the fires and the floods.
Given that apparent correlation, the company said it makes a lot of public policy sense to use satellite imagery and other knowledge of where wildfires have occurred as a tool to better protect the public in scenarios where there may be increased risks of flooding.
“It seems clear that accurate and timely mapping of wildfire damage is an important part of being able to assess the risk that severe flooding poses to our settlements and critical infrastructure,” the SparksGeo report concluded.
Letting communities in harm’s way know of such risks well in advance would give them a chance to proactively invest in flood-protection infrastructure and reduce the likelihood of last-minute, frantic scrambling as was the case in Abbotsford last November when the Barrowtown pump station was only prevented from being overrun by rising floodwaters by the heroic, last-ditch efforts of a volunteer sandbagging crew.
Merritt was never given that opportunity. But in 2007, the community of Terrace was.
That year there was widespread fear that major rivers like the Skeena in the Terrace area and the Lower Fraser could overtop causing extensive damage. The culprit was a huge snow pack that Chapman and others predicted had the potential to cause extensive damage.
Forewarned with that knowledge and the assistance of $200,000 in provincial and federal funds, Terrace armoured its sewage plants treatment lagoons with tons of additional rock as well as digging a deep 100-metre-long trench and filling it with rock to prevent the Skeena from encroaching on and destroying the multi-million dollar facility. The funds were part of $33 million made available by both governments to communities deemed to be in harm’s way that spring.
Three of the most-intense wildfires detailed in the SparksGeo report were the July Mountain, Lytton Creek and Tremont Creek blazes. Chapman considered all three in his report and found the significant areas of land burned in each amplified the flood risk.
His analysis is that the July Mountain fire burned 26 per cent of the Coldwater River watershed at Brookmere and 16 per cent of the Coldwater River watershed at Merritt. That fire, combined with those at Lytton Creek and Tremont Creek, burned a further 13 per cent of the Nicola River watershed at Spences Bridge.
Shortwave infrared satellite image of the July Mountain Fire (reddish brown area). The Coldwater River snakes along the fire’s lower edge on the left and then punches through the centre of the burn as it heads toward Merritt.
SWIR image of the Lytton Creek Fire. The Fraser River is on the left. The Nicola River can be seen cutting through the eastern section of the burned area on the right as it heads for the Thompson River.
SWIR image of the Tremont Creek Fire. Kamloops Lake can be seen in the upper right corner, the Thompson River on the left.
One effect of such fires is to blanket once-absorbent forest soils with a wax-like coating—a result of chemical changes that occur during and immediately after fires. This can make them “hydrophobic” or water repellant.
In an interview, Flannigan said that wildfires can have profound consequences as far as water runoff is concerned.
“Some studies suggest as much as seven times more water flow between a forested watershed and a burned or harvested [logged] watershed,” Flannigan says. “Of course, it depends on many factors, but it is not unusual to see that kind of increase.”
He added that in the case of “hydrophobic ash,” it acts “almost like cement. The water just runs straight down based on gravity, no absorption.”
In his report, Chapman says the extensive area of land burned in key areas played a “compelling role” in the flooding that followed and that knowledge of where wildfires occur in future years and their proximity to vulnerable communities must become part of the flood forecasting and emergency planning regime.
“It is probable that these fires were major contributing factors, taking what would have been a large rain and snowmelt flood and creating an unprecedented behemoth catastrophic flood with a 1000 plus--year return period,” Chapman wrote.
Chapman notes that forest fire data are provided by the Northwest River Forecast Center in Portland Oregon as part of their flood forecast information for Washington and Oregon, but that similar information does not seem to be considered in BC. Flood forecasting and the models used to predict site-specific flood threats would be dramatically improved, in Chapman’s opinion, if two things happened:
The Ministry of Forests clearly recognized the vulnerability that certain communities face in the event of rain-on-snow events and built that knowledge into flood forecast models.
The ministry ensured that information on areas burned by wildfires be built into such models as well and be considered as a key risk factor when deciding when and where to issue flood warnings. This would involve much more information-sharing between water and wildfire experts spread through a very large ministry.
Such changes become even more crucial with climate change, something the provincial government was specifically warned about in 2010 by Jim Mattison, a long-time civil servant and formerly the provincial government’s top water official.
In a report that he wrote as a consultant that year, Mattison noted climate change was starting to “affect the lives of citizens every day.” This demanded improved and more-effective forecasting, he said, which was one reason he advocated for more than doubling of BC’s Forecast Centre staff. Today, 12 years after his report was submitted, staffing levels stand at six, one more than they were when Mattison issued his report and six positions below the 12 he said were needed.
Mattison also warned that not enough data were being used by Forecast Centre staff to plug into their predictive flood models and therefore the models were “limited in their ability to provide accurate flow forecasts.”
In its 2022 budget, the provincial government indicated the River Forecast Centre and provincial floodplain mapping programs will be expanded.
The logging industry and flooding frequency
The word anthropogenic has been joined at the hip with climate change because unlike previous dramatic shifts in the earth’s climate going back hundreds of millions of years, today’s shifting climate is being driven by human activities.
But there are also more immediate human activities to be concerned about. One of the biggest in a mountainous, once extensively and naturally forested province is clearcut logging and related road-building activities.
In recent decades, logging rates have accelerated to unprecedented levels, particularly in BC’s vast interior region, where the provincial government actively encouraged the logging industry to dramatically increase logging rates starting more than 20 years ago.
The pretext for what became known as “the uplift,” was that mountain pine beetle populations had exploded in number thanks to generally warmer winters and killed tens of millions of lodgepole pine trees - the most prevalent tree species in BC’s interior region.
“Salvaging” those dead trees before they lost their value became the goal, with the government giving industry the green light to log an additional 11 million cubic metres of trees per year. But turbo-charging logging rates had serious ecological and hydrological consequences as droves of healthy, living trees were cut down along with the beetle-attacked ones. By the time all this bonus logging was done, up to 63 million cubic metres of additional trees were logged, enough to fill a line of logging trucks bumper to bumper from Vancouver to Halifax five times over.
Timelapse images of logging in the Coldwater River Watershed, including an area burned by the July Mountain Fire in 2021.
Not surprisingly, by the government’s own admission logging rates are now poised to crash, much like the ecosystems that once supported healthy forests.
Younes Alila is a hydrological engineer and professor at the University of BC who specializes in forest hydrology and watershed management issues. Over years of study, he has concluded that “the flood regime in BC is super-sensitive to disturbances of any kind,” including logging activities, wildfires and climate change. Such disturbances are likely to result not just in the increasing severity of future floods but in their increased frequency. And their impacts, Alila warns, will be long-lasting.
“British Columbians are in for a hell of a ride for decades to come,” he predicts.
In the 1990s, when he joined UBC’s Faculty of Forestry, Alila recalls there were limits on the amount of logging that could occur in any one watershed, the limits generally 25 per cent. But that subsequently went out the window in the logging free-for-all that followed.
“That threshold is not used anymore,” Alila said during an interview with CBC Radio a few weeks after last November’s floods. “Over the last 20 years, we have been clearcut logging watersheds across all sizes by as much as 40 per cent, 50 per cent, 60 per cent and even more, which, of course, increases substantially the risk of flooding. My research shows that the flood regime is highly sensitive to clearcut logging in both small and large watersheds. As little as 20 per cent logging in large watersheds causes a 20-year, a 50-year and a 100-year flood event . . . to become four to 10 times more frequent.”
A sensitive and fragile flood regime
“Entire ecosystems,” are being impacted by logging at such a scale, Alila warned, noting that if you could drop a hat out of an airplane flying over parts of the province today there is a 90 per cent chance it would fall in an area of forest that had been logged.
Alila says that restoring more natural water flows in logged BC Interior forests takes a very long time. In the first 20 years following logging and replanting, only 20 per cent of the “hydrological functionality” is restored. (Logging roads and the threats they pose to landslides and altered water flows are discussed in a second piece that focuses on the tragic deaths of five people on the Duffey Lake Road during last November’s heavy rains.)
“The way that we have been logging and increasing the cut rate and increasing cutblock size in my opinion does not reflect an industry or even a government that appreciates how sensitive and how fragile the flood regime in BC is to land use change and global warming,” Alila told CBC’s Chris Walker, adding that nothing less than a “complete paradigm shift” is needed to the way we manage forests.
In his analysis, Chapman also focuses on logging and related logging road densities in the Coldwater, Nicola and Tulameen river basins. His conclusion is that “there is a strong possibility for historic forestry activity to be associated with the extreme peak flows in those rivers and the flood-related damage to follow.
“Clear-cutting and forest fires encompass 35% of the basin of the Tulameen River at Princeton, and 41% of the basin of the Coldwater River at Merritt. Road densities are also very high at 1.85 km/km2, and 1.5km/ km2, respectively in the two basins, potentially augmenting the rapid movement of storm rainfall into stream channels, causing peak flows to be increased,” he wrote.
Alila subsequently outlined numerous things he feels must change in revised provincial forestry legislation.
An overhauled system should require a watershed assessment to be done prior to logging permits being issued. This includes projections of how logging may impact such things as floods, droughts, landslides and water yields, as well as considering the impacts of logging against the backdrop of a changing climate, Alila says.
He also recommends that thresholds be reinstated placing strict limits on the overall area of forest in a watershed that can be logged and that priority should be given to community watersheds, which are often critical to the provision of clean drinking water, watersheds with high fisheries values and large watersheds that drain into urban and semi urban areas, some of which may be on floodplains and therefore extremely vulnerable to flood-related damage.
“We cannot continue to log as if there is no connection between what we do to the landscape in the upland and downstream lowland values, especially when human lives and costly infrastructure are in harm’s way,” Alila says.
He would also like to see the important hydrological functions performed by forests embedded into the critically important allowable annual cut decisions made by the province’s chief forester.
Those decisions set the maximum logging threshold in various timber supply areas in the province and, in Alila’s view, have never properly accounted for the important hydrological role played by forests or how long it takes logged forests to recover once they have been logged. If such accounting happened, less forest would be logged.
Lastly, Alila says successive governments have failed to grapple with the outstanding issues of cumulative impacts of multiple industrial operations—logging, mining, natural gas—in watersheds over time.
“For decades, no considerations have been given in BC to cumulative effects of land use,” Alila writes, noting that cumulative effects can apply to the forest industry itself, as is often the case because many logging companies may operate at the same time in the same watershed “with little or no coordination” from the government.
“In a nutshell, forest management in BC has never been conducted in ways that portray an appreciation of the value of forest cover in maintaining the overall health of the ecosystem,” he says.
In northeast BC, the overall health of the forests was understood by First Nations in the region because from one generation to the next they hunted wildlife, caught fish, trapped fur bearing animals, harvested berries and gathered medicinal plants.
When their leaders signed Treaty 8 in 1899, the agreement recognized the rights of First Nation members to continue to be able to hunt, fish and trap as before.
More than a century later, when members of the Blueberry River First Nation realized how multiple industrial developments—including clearcut logging, hydroelectric dams, natural gas drilling and fracking operations—had so fragmented their lands that they could no longer carry out their treaty-protected rights over much of their traditional territory, they went to court.
In a landmark decision last year, the BC Supreme Court ruled the provincial government had unjustifiably infringed on their rights through the cumulative effects of numerous government-approved industrial developments. The ruling effectively brought a great deal of industrial activity in the Nation’s traditional territory to a standstill, pending a court-ordered negotiation between the provincial government and the Nation.
The Supreme Court decision may only foreshadow what is to come. In addition to being named in the class action suit in Sumas Prairie, another class action naming the provincial government has been launched by citizens in the Grand Forks area who were flooded out of their homes a few years ago, and who blame the cumulative impacts of government-approved logging and logging road developments in the Granby and Kettle watersheds for the devastation that befell them.
Years of approving one industrial development after another and disregarding cumulative impacts are coming back to haunt the provincial government in a big way as residents, businesses and Indigenous and non-Indigenous communities alike across the province deal with the fallout. The bills for the destruction wreaked last November now approach $9 billion, and who knows what costs may be added into the mix as a result of the class action suits the government now faces.
Climate change is making a bad situation of the government’s own making even worse. Highlighting, again, the need for corrective action.
Ben Parfitt is a resource policy analyst with the Canadian Centre for Policy Alternatives, and a longtime investigative writer.