"Greater chance of flooding after devastating bush fires this summer." - Fact
Rains follow drought. Yes, even moderate rains have the potential to cause severe flooding, landslides and devastation not only along the banks of the Clyde River but to the smaller streams and rivers.
Bushfires dramatically change the terrain. The ground is charred, barren and unable to absorb water or even hold the water for a short period after a shower. The rain falls and runs down the slope gather more water as it proceeds. It causes greater erosion and moves all before it until it reaches a gully where it forms a stream which due to the compound effect becomes a flood. Yes even in the creek behind your house.
Floods, mudflows and landslides are the next challenge we in the South Coast will have to face even during the early rebuilding phase.
Just imagine heavy rain along the side of the Kings Highway with no vegetation to hold the soil. The culverts full of water and the high embankments with dead and blackened trees teetering on the edge ready to topple with the next gust of wind. A landslide or even a minor mud slide could cut the road without any warning.
Emergency services without the fear of a fire storm could clear the highway within hours and we would not have to face another disruption but what if they closed the road “for your safety” until they can assess the potential danger. What would that do to our already fragile mental health.
But that is not the real issue. When the rains come they always flow into the rivers and creeks. The Clyde and the Tomakin rivers. With no protective vegetation it will rush towards the sea down the major arterial rivers. Now we know or so the GHD consultants tell (Transport for NSW) that the CBD and MacKay Park will flood with a one in a hundred year flood with just normal vegetation on the banks but they did not model after these devastating fires with the blackened ground cover.
And what of the two sets of bridge piles still in the river just upstream of the town? GHD modelling indicated a significant increase in erosion and turbulence with moderate flooding.
The Association is not being alarmist however we do know that there are inadequate water craft in the area to be tasked to assist people caught in these potential flood situations. The question is what has Council done to prepare for this potential challenge? It appears that they had an out of date bushfire plan and it appears they have no flood mitigation or response plan. They do however have a Tomakin flood study indicating where the flood waters will rise to but that may well be to guide for building approvals. BUT plans nil.
The matter of the impact of the ash on the water quality and ecology and fish will be the subject of a future post.
