Levee helps reduce flood crisis
LISMORE businesswoman Suzan Sanders went to last night’s SES flood preparation seminar to find out how the CBD would react to a major flood, now that the new levee is complete.
Businessman Charles Brown was there for the same reason, with both shopowners reporting about 450mm through their premises in 2000, the last CBD flood.
Last May’s flood didn’t overtop the levee, neither did the 2005 flood, which came after the levee was finished.
But future floods certainly will and with so much inundation between Coffs Harbour and Kempsey this year it is only a matter of time before Lismore is affected.
According to flood engineer Toong Chin, an officer with the Department of Conservation, Climate Change and Water, future floods will inundate the CBD from Browns Creek Car Park and Gas Works Creek, whereas before Magellan Street delivered the bulk of water directly into the shopping district.
Future floods will be held back and Ballina Street will remain open for two to three hours longer, giving residents in North and South Lismore a better chance of escape.
But once the levee overtops, at 11m, the Lismore basin and CBD will flood quickly – in about one hour.
In the case of a 1:100 year flood, something a bit greater than the 1974 event, water will first stream into the basin from Browns Creek Car Park and Richmond Lane, with high and dangerous velocity expected there.
Next, water will slowly rise from Gas Works Creek before breaching Ballina Road and helping to inundate the basin. Finally, water will overtop the levee at Magellan Street, completing the flooding.