Being such a low-lying area (much of it just a few metres above AHD*), there are some concerns about the future of the Thompson Beach area in terms of inundation related to rising seas associated with climate change.
You’ll notice that many of the new houses being constructed are elevated. This isn’t always just about capturing the amazing views.
Thompson Beach is protected somewhat by its coastal dune system. In the 1990’s, levees were also built to the foreshore in the road reserve and at each end of the settlement to join with the natural dune system. However, at that point in time, there was no requirement to take into account the degree of potential sea level rise associated with climate change.
When I was considering purchasing real estate in Thompson Beach, the potential for damage from a combination of sea level rise, storm surges and king tides was something I looked into.
Like many low lying settlements, Thompson Beach may be susceptible to flooding from severe storm surges associated with king tides in the future.
A section of Thompson Beach is vulnerable to a 2.8m AHD event, but this may be mitigated through increasing height of the relevant section of levee. It also appears feasible to protect the settlement against a yet-to-be-experienced ~ 3.0m AHD event.
However, a 3.7m AHD event would likely inundate most of the settlement and protecting it against such an event may not be feasible according to a Uni SA study.
The good news is that for the foreseeable future, a severe storm surge/king tide event of 3.7m AHD probably won’t occur until the latter part of this century (as I understand the situation), and that’s assuming sea level rise predictions of 1.0m by 2100 occur.
With any other flooding that may occur prior, there should be plenty of warning, it will be slow moving and should be reasonable short in duration for much of the settlement – just a few hours; coinciding with the peak of a king tide in stormy conditions.
At this stage, there haven’t been any significant flooding events in Thompson Beach that I’m aware of – even during the major floods of 2016 that saw other areas in the region go under water.
If you’re considering buying land at Thompson Beach, it makes good sense to build elevated as most insurance policies won’t cover for damage caused by sea action – and that’s what a storm surge is considered to be.
Council may also decide to make it a condition of new builds that any dwelling constructed that isn’t built above a certain level be elevated or even moved in the future if sea level rise predictions materialise.
While it all may sound a little unsettling, there are many places in the world where people have been living with intermittent flooding issues for hundreds, if not thousands, of years.
Like living in a bushfire prone area, it’s just a matter of being aware, researching and planning ahead – and hopefully some action will occur on the part of relevant government authorities to do what is feasible to protect the town.
For more information on the potential threat posed by storm surges and sea level rise at Thompson Beach, read this Uni SA study carried out a couple of years ago and the recommendations that were made to Council.
Even if you don’t believe in climate change, nature does as it pleases regardless of our opinions – so it’s still worthwhile bearing potential inundation issues in mind.
*AHD stands for Australian Height Datum, the information that sets mean sea level as zero elevation. Mean sea level is halfway between the average levels of high and low water. Mean sea level varies from location to location.