 Shuswap Lake high water (June 26, 2012) Photo credit: Ellen Atkin  TCH bridge over Salmon River (May 22/11), Salmon Arm |
THE RIVER DELTA AND FLOOD RISKMovement of water through the river delta is a complex balance of give and take. Alter the balance and you alter flood risk and consequences. Many jurisdictions recognize their past mistakes and now manage river and floodplain development differently. Others mitigate damage as best they are able by attempting to rehabilitate normal river and floodplain function.To better understand the Salmon River, floodplain and Shuswap Lake, WA:TER has gathered information from many sources. For those interested in greater detail, follow the links provided. SALMON RIVER FLOOD HAZARD [ an overview of flood hazard indicators ] FLOOD HAZARD PUBLIC MEETING [ held March 15, 2011 in Salmon Arm ] EVIDENCE FOR AN ACTIVE FLOODPLAIN [ on our Science page ] VIRTUAL DELTA WALK [ a short video tour that doesn't require hip waders ] FLOOD RISK ASSESSMENT NEEDED [ CPR Engineering Services, Terratech Consulting, Streamworks Consulting, BC Rivers Consulting and Neskonlith Indian Band call for flood risk assessment ] FLOOD HAZARD QUOTES [ quotes drawn from the professional literature ]  
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SALMON RIVER FLOOD HAZARD
Park Mountain automated snow pillow gauge, is considered to be a good predictor of flooding potential within the South Thompson.Flood warnings and advisories, and snow survey summaries and water supply bulletins can be found on the BC Forests, Lands and Natural Resource Operations River Forecast Centre website. A high streamflow advisory was issued for the Salmon River near Falkland May 11, 2011
The average temperature for April is a good indicator of flooding potential in the South Thompson area. Typically a below normal April temperature is a good indication of a higher than normal flood condition while an above normal April temperature is a good indicator of lower than normal flood potential. Average April temperatures at the Salmon Arm Airport were about 7.9 degrees. (National Climate Data and Information Archive)
A cool, early spring followed by either a hot spell and/or extended wet period in late May and/or early June can bring very high flood waters. Such conditions have been reported in 1913, 1928, 1948 and 1972 as well as more recently in 1996, 1997, 1999 and 2008. Lower than average stream and river level at the end of April are also a good indication of a higher than average flood potential. Real time river level information for the Salmon River can be found on the Environment Canada Water Office website.
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PUBLIC MEETING ON FLOOD HAZARD IN SALMON ARM
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Listed below are video highlights of presentations made by a First Nations representative and three engineering professionals with flood risk expertise, at the public meeting sponsored by WA:TER, March 15, 2011. 1. Bonnie Thomas, President, Switzmalph Cultural Society Presentation 2. Matthias Jakob, P.Geo., BGC Engineering Presentation Introduction - Part I - Part II - Part III 3. Paul Doyle, P.Eng., BC Rivers Consulting Presentation Part I - Part II 4. Alan Bates, P.Eng., Streamworks Consulting Presentation 5. Questions from the floor - a) Is it appropriate to use Aboriginal knowledge? b) Are floodplain guidelines the law? c) What guideline changes would you suggest? d) How should bridges be designed? e) Does lack of political will influence professionals? f) How will increasing river flow affect the floodplain? |
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Presenters' Message
Rivers flood, sometimes drastically. The consequences, for people, can be devastating or beneficial. Devastation occurs, sooner or later, if people build on floodplains and restrict channel changes. Natural floodplains provide flood water storage, critical fish and wildlife habitat, rich soils, very productive vegetation, water purification and green space. European cities, with records of multiple drastic floods, are returning their channelized rivers back to a meandering state in order to reduce destructive flooding. The likelihood of drastic flooding of the Salmon River has increased due to beetle killed forests, logging, agriculture, development and weather change. The consequences are unknown, because no recent studies of likely flood levels exist. The provincially designated 200-year floodplain is seriously out of date. Many homes, businesses, the highway and CPR are at risk. Records of the floods of 1894, 1948 and 1972 provide some valuable insights. Consequently, a professional assessment of flood hazard and risk is recommended.
Some Details
First Nations Concerns
Neskonlith and Adams Lake Bands have not been included in decision making and consideration of possible hardships caused by floodplain development adjacent to Native land.
The importance of First Nations knowledge and their reliance on indigenous plants and wildlife appears to have been neglected by the local government.
The local government has not informed the provincial and federal governments of First Nations' concerns as the Local Government Act requires.Flooding
Europeans recognize that attempting to protect properties by draining floodplains does not work. Natural benefits of meandering rivers and associated wetlands are impaired or lost. Water quality declines when rivers are altered.
Efforts to channelize rivers do not work; much of Alan Bates' work is restoring river channels to their condition before being modified by man.
Flood hazards increase as homes and other developments are allowed on floodplains.
In North America, accurate records for 200-year and longer durations do not exist, so predictions of flood hazards are unreliable.
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The currently used 200-year-floodplain is out of date due to beetle killed forests, development, agriculture, logging and weather change. Local governments have had responsibility for land use planning and development since 1974. Some have created by-laws to deal with flood hazard and risk, but many have not. The Salmon River floodplain is classified as hazardous and active due to frequent channel changes. The 1894 flood was much greater than that of 1972 [adjacent photograph from GeoTour Guide for Kamloops, Geological Survey of Canada Open File 5810]. Development on floodplains has always been controversial.Ecology Spring, Sockeye and Coho Salmon habitat needs to be protected, if population recoveries are to occur. Leaving wetlands and fish habitat in a natural condition will protect Shuswap Lake water quality. Filling wetlands influences their filtration function and changes groundwater flow. Even logging roads through wetlands result in flood death on one side and drought death on the other. |
2 The non-profit organization seeking to implement Dr. Mary Thomas' vision.
Salmon Arm Observer coverage of March 15, 2011 public presentation
EXAMINING FLOOD RISK
By Martha Wickett - Salmon Arm Observer March 30, 2011It's time to reconsider flood levels of the Salmon River in case the area experiences, sooner than later, a flood like that in 1894.
This was one of the messages carried by water resource specialists who spoke in Salmon Arm regarding rivers, flooding and the Salmon River delta.
Paul Doyle, a hydrotechnical engineer, told the Observer the Salmon River delta is a complicated hydrologic situation because of several factors. Among them are the limited openings in the highway embankment where the bridge is, and in the railway embankment where the two rail bridges are.
"Partial obstruction of flows in the Salmon River are certainly more likely to occur when you have those limited openings in both those embankments," he said, noting partial plugging of the waterway openings can occur when the river deposits material, sometimes trees, during high flow. There's also the fact the lake level is what controls the water levels back as you go upstream on the river, plus the river has been altered in some spots by berms and dikes.
Then there's climate change.
"A lot of people brush that off. It's happening, it's real, it's going to get a lot worse and it's happening faster," Doyle said. Considering all the factors together, "those are the main things people can't tie down no matter how smart or knowledgeable they think they are."
Doyle would like to see a re-investigation of the flood-plain mapping done in 1990, given that stream flows over the past 20 years have shown changes, and mapping techniques have improved.
"What's particularly unsettling to me, we've seen '72 and '48 (floods in those years), but the 1894 flood is poorly documented," he said, noting it dwarfed any seen since. "People think '48 and '72 were pretty big events in the region and on the Salmon (River) but they were nothing like it could be."
As a person who studies such events, he says, "Wild thing happen when there's an extreme flood that people don't even think about. I can assure people strange things can happen; it's not to anybody's benefit when you get a big flood."
Alan Bates is a river engineer from Salmon Arm whose area of expertise is river restoration, working mainly in the Southern Interior and the Kootenays.
"If you can give a river space to do what it needs to do, it's a lot better. Anytime you start crowding them..., the more you squeeze it, the more it fights back. That's a simplification, but that's what they've learned in Europe," Bates said.
Rather than have a town sit on a river, he said, farmers' fields, hiking trails and playgrounds are better alternatives for a floodplain.
"When the flood comes, you can say, 'Oh well, we haven't lost a lot of infrastructure."
Referring specifically to the Salmon River delta, he said it helps protect the water quality of Shuswap Lake.
"They build water treatment plants to mimic wetlands," he continued, noting that debris, sediment and nutrients come down in a flood, which the delta processes.
Measuring how high a river floods is only one issue to consider," he said. "If building occurs on a floodplain, then what would have been processed by the delta may be forced out into the lake. If too much building occurs, diking and dredging will have to take place.
"If you leave it natural, it takes care of itself."
His wish, as a Salmon Arm resident, is that he never has to restore anything in the Salmon River floodplain or delta.
The engineers spoke as part of a meeting hosted by Wa:ter, (Wetland Alliance: The Ecological Response), to provide information about water movement in the Salmon River delta. It is a topic the group has been pushing to have studied, particularly because of plans to build a shopping centre adjacent to the river.
FLOOD RISK ASSESSMENT NEEDED
Canadian Pacific Railway, Neskonlith Indian Band (see SA Observer article "City Expecting Response"), Streamworks Consulting, BC Rivers Consulting and WA:TER (see March 15, 2011 public flood risk presentation) have urged the City of Salmon Arm to engage the services of a recognized consulting engineer with expertise in surface water hydrology and fluvial geomorphology to assess flood risk in Salmon Arm.
TERRATECH CONSULTING REQUESTS FLOOD RISK ASSESSMENT - November & December, 2010
On February 6, 2012, Calvin van Buskirk, from Terratech Consulting, made a presentation to Salmon Arm Mayor and Council on the need for a flood risk assessment to guide the City's long term planning. A second presentation on the same topic, at a WA:TER hosted public meeting on February 16, 2012, can be viewed by clicking the following links. These presentations follow a written submission in December 2010.TERRATECH PRESENTATION: Introduction, Part 1, Part 2, Part 3, Part 4, Part 5
December 21, 2010
To: Mayor and Council, City of Salmon Arm
As the fourth reading for the proposed rezoning of property located within the active portion of the Salmon River delta has now been held, I am writing to inform you of correspondence I have had with City staff over the past two months regarding the City's management of flood prone areas.
The first attachment is an email to Dale McTaggart and includes a copy of a letter sent to Corey Paiement dated 9 November 2010.
The second attachment is a follow-up e-mail to Dale McTaggart which includes an attachment titled "Flood Hazard Area Land Use Management Guidelines".
The third is an e-mail to Corey Paiement and Dale McTaggart regarding the value of and risk posed to Urban Wetlands.
The fourth is an article from the Association of Professional Engineers and Geoscientists regarding Flood Hazard and Risk Assessment.
The fifth is the City's response to the 9 November letter.
The sixth attachment is a brief description of deltas.
Based on the attached, I would like to draw your attention to the following facts as I see them:
1. Neither the City nor the Developer have publicly acknowledged that either party has any technical knowledge about the function or dynamics of the Salmon River Delta (this was made clear by 2 through 6 below).
2. The City encouraged the development of the subject site by supporting its removal from the agricultural land reserve.
3. The City, through contracts, direct or indirect, with local earthworks contractors contributed to the deposition of fill within the floodwater channel(s) on the subject site.
4. The City did not request that the developers provide either a flood hazard or flood risk assessment to support their application for rezoning.
5. The City did not request an environmental impact assessment with respect to the proposed development.
6. The developer hired two professional biologists to assess the 1 in 5 year flood level for the Salmon River rather than a fluvial geomorphologist. The developer continued working with the biologists even after serious mistakes were made in the first RAR report.
7. According to the Provincial Government, the City has the authority to request any studies it feels are necessary to support an application for rezoning of land.
8. The City's approach to managing flood hazard and risk does not meet the recommended minimum requirements as outlined in the attached provincial government "Flood Hazard Area Land Use Management Guidelines" that were prepared in support of the transfer of this authority to the City.
9. The "Flood Hazard Area Land Use Management Guidelines" would not have permitted the infilling of the flood channels on the subject property.
10. The existing fill material cannot be safely built upon and must be removed along with the underlying topsoil (this requirement is included within the geotechnical report provided by the developers).
11. Although the guideline being prepared by APEGBC does not currently form Best Management Practices as it has not been released, much of the content of the document as included in the attached "Flood Risk Assessments in Canada" article would currently be considered as a standard of practice. In addition, the "Flood Hazard Area Land Use Management Guidelines" would form part of the current standard of practice.
12. The 200 year flood design discharge of about 59 cubic metres per second used in the 1990 study that produced the current floodplain mapping for the Salmon River was reached in 1996 and 1997. Given this, plus the additional 20 years of data now available, the floodplain mapping and current elevations used to support development within the Salmon River area are clearly out of date and should be reviewed and revised.
13. The placement of fill is not regulated within the City of Salmon Arm even though many other Cities and Municipalities recognize the importance of regulating fill placement from the perspective of responsible land use management. The lack of regulation permits irresponsible fill placement that can lead to flooding, landslides, sedimentation and environmental damage. Within BC, Canada and around the world, the cost of lessons learned in terms of economic losses, environmental losses and the loss of life have been staggering.
I would like to request that the Mayor and Council consider the above and attached information and provide appropriate instruction to the City staff such that development within or adjacent to flood-prone areas is undertaken in a responsible manner that acknowledges and safeguards the interests of all stakeholders.
In addition, I would request that the City's approach to management of flood-prone areas and the regulation of fill removal and fill placement be updated to safeguard the public and limit the potential for financial losses and environmental damage.
In closing, I would like to state that I am not against development in Salmon Arm or even at this site, however, in my professional opinion, permanently infilling an active flood channel without knowledge of the implications of such actions does not make any sense. That said, it should be possible to reconfigure the proposed development to reinstate the flood channel and still provide the size of development requested by the developer. By exploring such opportunities, I feel a significant amount of the strong opposition to this development, which has divided our community, could be put to rest.
I look forward to a response from the Mayor and Council.
If you have any questions or comments, please contact me.
Yours truly
Terratech Consulting Ltd.
Calvin VanBuskirk, P.Eng., FEC, P.Geo.
PS. For those who are not familiar with Terratech Consulting, we have been in business in Salmon Arm since 1988 and have donated several thousands of dollars in materials, design and consulting services to community projects including: the waterfront Gazebo; Greenways; Shuswap Trail Alliance and the Haney Heritage Park Bridge over Canoe Creek.
Attachments: City of Salmon Arm reply, flood risk assessment, BC flood hazard area guidelines, delta definitions
CPR ENGINEERING SERVICES REQUESTS FLOOD RISK ASSESSMENT - December 15, 2010
Five days before Council passed 4th reading for the SmartCentres development proposal for the Salmon River floodplain, Canadian Pacific Railway (CPR) wrote"requesting that the City of Salmon Arm either retain directly or require that the proponent retain the services of a recognized consulting engineer with expertise in surface water hydrology and fluvial geomorphology to assess the changes in flood risk introduced by the existing and proposed fill and development within the SmartCentres property. The existing fill and the proposed fill are within the jurisdiction of the City of Salmon Arm and therefore the CPR relies on the City to ensure that adequate safety consideration are preserved as per the Railway Safety Act of Canada (Part III, Section 24c). CPR is specifically concerned that the existing and proposed fill will direct more flow to the CPR Mile 64.60 bridge [Salmon River] compared to the current condition. Currently during extreme flood conditions the Salmon River over tops its banks and flows through both bridges."Excerpt from Dec. 15/10 CPR letter (pages 1 & 2).
CITY EXPECTING RESPONSE FROM SMARTCENTRES
By Martha Wickett - Salmon Arm Observer Published: June 28, 2011 6:00 PMCalls for a flood risk assessment of the Salmon River delta before development occurs on the site is expected to prompt a response from SmartCentres.
The Neskonlith Indian Band wrote to the City of Salmon Arm on June 3, reiterating its concerns about flooding and explaining that its legal counsel had retained an expert, Prof. Michael Church, to determine if flood risk was being properly assessed for the proposed shopping centre.
Church states in his report there's a consistent trend of increasing flows in the Salmon River, and the development in the form currently proposed doesn't meet criteria to be above flood construction level. He recommends the flood profile be reanalyzed using current data and the flood hazard be reassessed.
"If the development was to proceed in its current form it is expected to flood in the near future," states the letter from the Neskonlith to the city. "This would result in the implementation of flood mitigation measures, which in turn could have a significant impact on neighbouring ecological values and adjacent properties, including the Neskonlith Indian Reserve Lands."
Mayor Marty Bootsma told the Observer Friday that Corey Paiement, the city's director of development and planning services, is going over the Church report and he thinks he has asked SmartCentres to prepare a response. "It's a wait and see," said Bootsma. "We'll see their response."
He noted that the environmentally hazardous area development permit application is expected to come to council shortly.
"We'll get the reports and staff input on it, and go from there."
Paiement stated Friday that SmartCentres is providing a response but the city hasn't yet received it.
On June 17, the Observer asked Carl Bannister, the city's chief administrative officer, what the city's approach to flood assessment is, given that the province in 2004 downloaded the responsibility for flood hazard area land-use management to local governments.
He said a flood hazard assessment of the delta is not currently being planned.
"We don't have any plans at this point and have not been given any direction from council to do any broad study of the Salmon River delta," he said, confirming that the city has received the Church report as well as the Matthias Jakob report commissioned by the Wa:ter group and is reviewing them, as are SmartCentres engineers.
"If there's a disagreement between professional engineers, that's something they need to sort out amongst themselves within their own association."
He said staff are reviewing all reports in view of local, provincial and federal regulations.
"If we have concerns that none of those are being met, we'll go from there."
FLOOD HAZARD QUOTES
Gilbert F. White: "The great tragedy of Katrina is that the hard lessons learned in ... earlier storms were blithely forgotten by all. After the great Mississippi River flood of 1927 wreaked havoc all along its course and came within a few feet of spilling over the river levees and inundating New Orleans, the growing city clamored for additional protection. Over the coming decades, the federal government erected a vast network of levees and spillways along the river and around the city, while giant new dams along the Missouri - the Mississippi's longest tributary - ponded water all the way to South Dakota. The system was billed as a triumph of engineering over nature. Yet Gilbert F. White, considered the "father of floodplain management", came to a far different conclusion, one that Katrina drove home with a vengeance. As a young University of Chicago geographer, White had studied the delta after the 1927 disaster and realized that much of the suffering could have been avoided. "Floods are 'acts of God,' " he wrote in 1942, "but flood losses are largely acts of man." White and his colleagues argued that dams, levees, and other flood protections may actually increase flood losses because they spur new development in the floodplain, which incurs catastrophic losses when man-made flood protections fail. The phenomenon came to be known as the "levee effect." (National Geographic)