Information from Geoscience Australia;
The Barron River is 165 kilometres long and it drains an area of 2,300 square kilometres. The River rises on the Atherton Tablelands and flows north through Mareeba before turning east to enter the lowland delta through the spectacular Barron Gorge below Kuranda. It is fed by several major tributaries on the Tableland, the largest of which are Granite Creek and the Clohesy River, while Freshwater Creek joins the Barron below the gorge. The delta covers about 45 square kilometres with Thomatis Creek/Richards Creek providing a distributary channel at the mouth. There are three dams in the Barron catchment, the Tinaroo Falls Dam (completed in 1958), the Barron Gorge Weir close to Kuranda (built in 1935 to provide storage for the Barron Falls hydro-electric power station) and the Copperlode Falls Dam (Lake Morris) on Freshwater Creek (completed in March 1976). None of these dams was constructed to provide a flood mitigation capacity. Given the configuration of the catchment and the location of these dams they have little influence on reducing a flood.
An extensive network of rainfall and river height gauging stations monitors the Barron River. A flood warning alert network was established jointly by the Bureau of Meteorology (www.bom.gov.au), the then Mulgrave Shire Council and the Cairns Port Authority in 1995. Stations in the network are linked by VHF radio to a base station computer in Cairns. The data produced by these instruments are provided to hydrological models to produce river height predictions on which flood warnings are based. Quantitative river height predictions are given for Kamerunga which is the reference gauge for flooding on the delta.
The Barron River was a much smaller river until it captured the Clohesy and part of the westward flowing Mitchell. This larger river formed the Barron Gorge.
Until the early 1900s, Freshwater Creek used to join the Barron River about one mile further upstream than it does today. A combination of floods and siltation have moved the confluence downstream.
Thomatis Creek was not a distributary of the Barron until the floods of 1932, when the systems joined and some of the Barron flood waters discharged into the ocean via Thomatis Creek.
Historically the mouth of the Barron has been in several different places along the coast. Most recently the Barron discharged at Ellie Point until the 1939 cyclone when flood waters entered the ocean two kilometres to the north, forming the present river mouth.
Information from Geoscience Australia;
It is clear from the river gauging record that the flood of late March to early April 1911 is the greatest flood on record. That flood was recorded at 15.37 metres on the Myola gauge (although this may not be directly comparable with heights at the current gauge). It was caused by widespread rain across the catchment between 31 March and 2 April 1911 including falls of 617 mm and 732 mm recorded at Kuranda on the last two successive days. This rain fell onto a catchment that had already been saturated by rain brought by a cyclone that crossed the coast near Port Douglas on 16 March. According to figures quoted in a study of flooding on the delta published in 1981, (Harbours and Marine, 1981), this record flood had a discharge of 7,221 cubic metres per second (cumecs) which was estimated to be around 70% of the estimated probable maximum discharge. This makes it an extreme and fairly rare event with an annual exceedance probability (AEP) of between 0.2% and 0.1% and an average recurrence interval (ARI) of between 500 and 1,000 years. There appears however to have been little damage given that there was little development other than some agriculture at that time on the Barron River delta.
The second greatest flood on record came two years later and was caused by a cyclone that crossed the coast about 70 kilometres north of Cairns on the night of 29-30 January 1913. A flood peak of 14.76 metres on the Myola gauge was recorded on 31 January. The discharge recorded in this flood was 6,569 cumecs putting it in the region of a 0.5 AEP event. Again there appears to have been little damage reported other than to crops on the floodplain.
1934 & 1963 floods
Further major floods measured on the Myola gauge occurred in;
March 1934 – 10.5m.
March 1967 – 11.62m at Myola, 9.5m at Kamerunga.
The third greatest on the Barron River was in March 1977. As with the 1911 flood this event was produced by a period of heavy rain and minor flooding in the catchment being followed within a few weeks by a second heavy rainfall episode. This flood reached a peak of 12.62 metres on the Myola gauge with a discharge of 4,556 cumecs, and 9.5 metres on the Kamerunga gauge. The Myola discharge rate would make this a 1:50 year flood on the basis of the most recent revisions of rainfall. The meteorological sequence is described in the Barron River delta flood study (Harbours & Marine, 1981) as follows;
The start of the wet season in February 1977 was marked by the development of tropical lows in the Gulf of Carpentaria and off the east coast. There was some easing of the weather on the 9th as these lows in the monsoonal trough moved away from the coast. Tropical cyclones Lily and Miles developed north and east respectively of Willis Island whilst the low in the Gulf moved onto the coast on the 10th and 11th bringing further heavy rain on those days. Tropical cyclones Lily and Miles were not particularly active and moved generally east to southeast before degenerating without directly affecting Queensland’s coastline. However tropical cyclone Nancy developed comparatively close to the coast on the 12th and maintained cyclonic strength for about 9 hours before crossing the coast near Bloomfield River mission, Wujal Wujal, as a rain depression in the early hours of the 13th.
As a result of these weather patterns the northern half of the state received heavy to flood rains during the first half of the month. During this period stations at Babinda and Innisfail recorded their highest monthly totals since records commenced. In the Barron River catchment high monthly totals above 600mm were recorded on the coast and in inland areas including most of the tableland.
Overbank flow from the Barron River and Thomatis Creek during the flood submerged the Captain Cook highway and Yorkeys Knob road pavements linking these floodwaters with the runoff from Avondale Creek catchment. However there was no flow across the Brinsmead-Kamerunga road north of the Barron nor any overland flow west of this road into Avondale Creek. Although large tracts of cane land were inundated there was no evidence of scouring.
The flood peak in the Barron River passed Lake Placid at 7.00am and reached b14 gauge at Machans Beach at 9.30am on 11 February 1977.
A similar weather pattern to February emerged in early March with a high pressure system in the Tasman Sea extending a ridge up to the monsoonal trough. This situation which continued for much of the first half of the month caused continuous showers and thunderstorms in the vicinity of the trough.
Again tropical low pressure systems became active in the trough developing in the Gulf and off the East Coast. The low in the Gulf eventually developed into tropical cyclone Cotto on the 7th. Tropical cyclone Cotto traversed Cape York Peninsula and moved down the east coast before recrossing it on the 8th and dissipating inland near Townsville.
Tropical cyclone Cotto brought particularly heavy flood rains to most areas of the Barron catchment on the 6th and 7th and subsequent heavy falls on the coast west to the range on the 8th and 9th as it degenerated.
The heavy falls which occurred overnight on the 6th resulted in the highest flood level measured at Myola since systematic recording began; 12.62m with a corresponding estimated discharge of 4,556 cubic metres per second.
The flood rose very steeply at one time at a rate of 0.75 metres per hour and the flood peak was almost coincident with the high tide which occurred around midday. The peak occurred at 9.00am at the Lake Placid kiosk and at 11.30am on the Yorkeys Knob road.
In addition significant flooding occurred in the built-up areas of Yorkeys Knob, Holloways Beach and Machans Beach. Most of the delta consisting mainly of cane land and non-urban areas was submerged during the flood. The records show that just in excess of 100 houses mainly located at Machans Beach were evacuated during the flood. Scouring was evident in the cane fields and on river banks particularly on the river bend adjacent to the end of the Cairns airport main runway.
There were six main flood events between 1 January and 6 March 1979, the largest in January 1979 recorded 10.7 metres in the Myola flood gauge and 9.4m at Kamerunga.