Carlyle Gardens Townsville Flood Risks

Carlyle Gardens Retirement Village, Townsville is between Ross River and Bohle Creek, in a very flat area that obviously formed as a flood plain. There is a flood drainage path nearby, and extensive flood control works along various roads nearby, mostly leading to the Ross River. The Ross River dam should reduce any flood risk from Ross River overflow into Bohle Creek. However Bohle Creek is a known flood trouble spot. The Carlyle Gardens Retirement Village property is built up above the natural level through extensive earthworks. The new houses at Carlyle Gardens seem to have a slab surface up to 300 mm above the level of the ground. The BOM rainfall figures show how much water is falling. See also my early notes on weather at Carlyle Gardens retirement resort.

Townsville Flood Maps

Unfortunately Townsville flood maps do not cover the Carlyle Gardens Retirement Resort area. I had been unable to locate equivalent flood data for Thuringowa. As the area is mostly recently developed, there is probably little relevant data in any case. The 7 metre flood of February 2007 and 7.5 metre flood of February 2008 are noted (large PDFs), and were not a problem (except for road closures).

Runoff from cyclonic events may be restricted by the effects of storm tides. This report on storm surge associated with Tropical Cyclone Charlotte on 12 and 13 January 2009 indicates likely effects on low areas.

Carlyle Gardens is outside the area affected by storm tide and surge.

Bohle River Flooding

Weather bureau notice of Bohle River flooding may be relevant to Carlyle Gardens, Townsville. This map of Ross and Bohle River flood warning system gives an idea of the relevant Ross and Bohle River area. There is a description of floods warnings on the Ross and Bohle Rivers. The major 1998 flood involved rainfall of over 400 mm over a four day period. Our experience in Airlie Beach (300 km south) once included 600 mm on our balcony over a 48 hour period.

There is a rather dated 1999 Thuringowa Urban Stormwater Management Report to give an idea of the issues in managing runoff from storms. The Bohle Plains Flood Planning Report of 2010 lists flood affected areas. The Overall Report provides a text description. Flood Maps for the Bohle River Part 1 provide maps (7 and especially 8) that cover the Carlyle Gardens area of Condon.

Carlyle Gardens is just outside the area expected to be affected.

Unlike some other developments nearby, the developer has built up the ground above the previous base level. The slab on ground concrete base is set above natural ground level, I estimate by around 250-300 mm.

1998 Flooding Aftermath

The record flood (in a very short span of data) was 8.38 metres in 1998, which flooded around 40 homes in Thuringowa. This involved rainfall of 400 mm over a four day period, concentrated in and around the area.

James Cook University Centre for Disaster Studies did a Townsville Thuringowa Post Disaster Household Survey after the January 1998 floods. Half the affected households had power outages of a half day. 15% of dwellings were inundated. Two thirds of roads were inundated. A third of victims had significant loss. Water supply was lost for 17% of houses for more than a half day. More than half never heard a severe weather warning. Over a half metre of rain fell on one day. This was followed by another 245 mm over two days, giving a record total of 794 mm over three days. Basically surface water was not able to drain away sufficiently quickly. King tides around the time also causes runoff to back up. There has been more than a decade of flood mitigation works since that time.