Geoff Helisma

The area east of the new roundabout at the intersection of Yamba Road and Carrs Drive has long been a problem for residents during and after a heavy downpour; and Clarence Valley Council (CVC) is about to have another look at the problem.

“We are engaging a consultant to answer whether or not the roundabout exacerbated the stormwater’s behaviour over recent times,” said CVC’s works and civil director Jamie Fleeting.

Mr Fleeting said staff would also “undertake a routine check of the pit and pipe network to ensure there are no blockages”.

Localised flooding, which followed a heavy downpour in Yamba on Friday December 17, was still evident hours after the rain had ceased.

According to the Bureau of Meteorology (BOM), the rain started bucketing down at 6am; 74mm of rain had fallen by 9am, and 16mm fell 9am to 9.30am –a total of 90mm in 3.5 hours, as per the Yamba’s weather station on Pilot Hill.

Yamba’s average rainfall for the month of December is 116.4mm.

Mr Fleeting said that heavy downpours coinciding with a high tide worsened the Yamba Road flooding.

There was a 1.53-metre hightide at 8am in Yamba last Friday, however, there is a lag time between the Yamba river entrance and upriver tide times; for example, the tide times at Maclean are two hours after Yamba’s.

Meanwhile, a reader sent in a picture of Edinburgh Drive, Townsend, allegedly flooded as a result of runoff from a nearby subdivision.

The man said it “fully washed away our front garden and it came within 10mm of going into our neighbour’s house”.

He said he “had been passed around” by various CVC staff, “without getting an answer” when enquiring about the problem.

The Independent contacted CVC’s environment director, Adam Cameron, who overseas development applications, however, he did not contact the paper prior to the print deadline.

La Niña’s effect on our weather

The BOM’s ‘climate outlook overview’ summary states, “January to March rainfall is likely to be above median for eastern Queensland and elsewhere along the eastern coast of Australia.

“Much of this area has an increased chance of receiving rainfall in the top 20 per cent of historical records.

“Conversely, scattered parts of western Australia are likely to be below median.

“The La Niña in the Pacific Ocean and the positive Southern Annular Mode (SAM) are likely influencing the above median rainfall outlooks.”

Regarding ‘climate influences’, the BOM advises:

• La Niña is established in the tropical Pacific. Climate models indicate La Niña thresholds are likely to be maintained until the end summer 2021-22. This pattern is likely to be contributing to the wetter than median outlooks for eastern Australia.
• The Indian Ocean Dipole (IOD) is likely to be neutral for the coming months. A neutral IOD has little influence on Australian climate.
• The Southern Annular Mode (SAM) has been positive for several weeks. It is expected to generally remain at positive levels until the end of the year. A positive SAM at this time of year typically brings above average rainfall to parts of eastern Australia, but below average rainfall for western Tasmania.
• Australia’s temperature and rainfall variability are also influenced by global warming caused by human activities. Australia’s climate has warmed by around 1.44 °C for the 1910–2019 period. Rainfall across northern Australia during its wet season (October–April) has increased since the late 1990s. In recent decades there has been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially across northern Australia.