Given what we’ve recently seen at and around Townsville should we on the Coffs Coast, and especially Bonville, be concerned ?
The climate is changing and there’s an increase in global floods now occurring. Townsville is now formally recognised as being subject to 1 in 100 year flood events and many more parts of Australia are likely to suffer from extreme weather events.
As we know, Bonville sits in a geographical flood plain and is within the 1 in 100 year flood extent. Significant areas of Bonville are not immune to recurring flooding and we should all remember what happened in 2009 when we had 3 major ‘once in a century’ flooding events.
For those with an interest, here are some definitions:
1. A one-hundred-year flood is a flood event that has a 1% probability of occurring in any given year. The 100-year flood is also referred to as the 1% flood, since its annual exceedance probability is 1%
2. The term “100-year flood” is used in an attempt to simplify the definition of a flood that statistically has a 1-percent chance of occurring in any given year. Likewise, the term “100-year storm” is used to define a rainfall event that statistically has this same 1-percent chance of occurring
Recurrence intervals for the annual peak stream flow at a given location changes if there are significant changes in the flow patterns at that location, possibly caused by an ‘impoundment’ or diversion of flow. The effects of development (conversion of land from agricultural uses to residential uses) on peak flows, is generally much greater for low-recurrence interval floods than for high-recurrence interval floods. During larger floods, the soil is saturated and does not have the capacity to absorb additional rainfall. Under these conditions, all of the rain that falls, whether on paved surfaces or on saturated soil, runs off and becomes stream flow. This is evidenced by seeing water from saturated lands spilling over local roads.
This issue has been known about as far back as 2009 as this article from the Coffs Coast Advocate shows https://www.coffscoastadvocate.com.au/news/former-mayor-says-boambee-a-bigger-problem/417686/
‘Noah’ is known to the editor as someone with expertise and experience in town and country planning