Plan or react: the choice for the highway

  • Sep. 15, 2004 4:00 p.m.

Submitted by Dr. Ian J. Walker, Assistant Professor, University of Victoria, Department of Geography–I was concerned to read in last week’s Observer (2 September, “Highway repair budget doubled”) Skeena district highway manager Don Ramsay downplay the significance of coastal erosion along highway 16 as a matter of ‘perspective’. As an earth scientist who has been studying the coast of Graham Island for three years and as a geographer who is concerned about climate change and it’s impacts on Haida Gwaii, I’d like to add a ‘bigger picture’ perspective.
Last January I wrote an article on the Christmas Eve storm stating that it was a rare and damaging one, but by no means a ‘freak of nature’. Since, I have examined water levels in Hecate Strait dating back to the early 1900s to estimate how rare this event really was. It’s no surprise that there are several big storms on record, confirming local accounts of Lionel Andrews, Doug Richardson and John Davies.
Our analysis shows the Christmas storm as the ‘100 year event’, not 200 as quoted by Mr. Ramsay. Note that engineers and planners are trained to rely on a ‘factor of safety’. However, by perceiving this storm as highly improbable and that rip-rap is anything more than a quick fix, it is my professional opinion that the Ministry of Transportation is grossly oversimplifying the efforts and costs required to maintain the coastal stretch of highway 16.
Mr. Ramsay is correct in stating that the science behind coastal conditions and storm prediction is lacking and complicated. To estimate the recurrence of damaging storms is a matter of statistics (and we know how fuzzy those can be). For example, the 200-year storm is an event (water level) that occurs with a frequency of 1/200 times (or 0.5%) over the period of record. This does NOT mean that this storm will happen every 200 years! Rather, it means that there is a 0.5% chance that a storm of that magnitude will happen in ANY year. So what, 0.5 or even 1% chance (for the 100 year storm) is slim, right? Statistically, yes. Realistically, no, if we look past budget and political timelines and if we consider how our climate and oceans are changing.
The accuracy of these statistics depends on 2 important things. First, it requires that storms of that magnitude have been measured before as predictions improve with an increasing number of similar observations. This is not the case here. The Christmas Eve storm was the highest surge level on record. Also consider that water level records in Hecate Strait are geologically short as they only extend back about 100 years or less. So, it’s not surprising that this event is ‘rare’ given our limited data (and perception). This is not to say that you cannot predict the 200 year storm if you do not have 200 years of record. It’s just a bit of a statistical stretch.
Second, storm statistics assume that nature is predictable. In other words, the same magnitude of storm will occur with the same frequency in the future. In the face of climate change, this is NOT the case. The World Meteorological Organization recently documented that storm surges, floods, landslides, droughts, tornados, etc. are all increasing in frequency and magnitude in most areas of the world. Hecate Strait is no exception. There is a greater chance now and in the future that high storms will occur more frequently than ‘natural’ statistics can predict as our climate and oceans change.
Jean Kalamarz was right in saying that, “a high tide in a regular storm [could] have the same effect”. Remember, that the Christmas Eve storm hit just after a low tide and could have been much worse. In fact, our analysis of all high storm surges shows that there has never been a major storm surge at high tide. There is no scientific explanation for this. It’s just plain luck. Well, not really. It’s just that we haven’t measured such an event yet. As you can imagine, it is very difficult to combine both tides and storm conditions (winds, pressure, temperature) that create storm surges to produce a reliable estimate of how often coastal damage may occur.
I mention all of this in advance of what is shaping up to be another El Ni̱o winter, which could mean warmer and higher waters in Hecate Strait. Timed properly, a lesser storm this season on higher waters or tides could spell more trouble. We need to recognize and plan for the fact that the erosion along coastal stretches of highway 16 is natural. This stretch of coast is retreating at rates of 1 Р3 metres per year. This is likely to increase as climate change causes Hecate Strait to rise by 15-17 cm per century and storm surges increase in frequency.
As decisions are made on how to spend this money, let’s keep in mind that climate change is reducing our chances in maintaining highway 16. Climate change is also reducing our abilities to predict safe scenarios for planning. Sections of the highway are simply so low and so close to the high tide (not surge) line, that no amount or size of rip rap will protect it. As I’ve said before, it is only a matter of years before a major engineering and/or relocation project must be considered. The increased highway budget would be better spent on planning for a realistic and sustainable future instead of reacting to the present. The only promise offered by the proposed Lawn Hill quarry is a sister spring for St. Mary.
(Ian Walker can be contacted at ijwalker@uvic.ca)

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