Historical flood information

Historical flood information for the Clarence Valley including flood levels and flows

While floods can be seen as the lifeline of the floodplain, their capacity for damage and economic loss is well understood.
 
From the first cedar-getters and European settlers in 1830 to the commencement of sugar farming in 1868, only relatively small floods topped the natural river banks near the early settlements.
 
Over the following few decades, however, the security of the floodplain was seriously questioned. Floods overtopping the banks in that period included the great flood of 1890, with a height of 24 feet. This would be equivalent to 7.834 metres AHD (Australian Height Datum).
 
One of the floods in 1950 killed two people, over 1000 head of cattle and damaged several thousand homes.
 
The most recent floods have occurred in 2001, 2009, 2011 and 2013 and have reached levels of - 7.70 m AHD, 7.37m AHD, 7.64m AHD and 8.08m AHD respectively.
 

Find out more:

Since flood records commenced in 1839, Grafton has been subject to over 120 floods - the highest being in January 2013 at 8.08m. The below graph shows the flood frequency in each month in Grafton since 1839. It shows the trend that floods occur more often from January – April, but it also shows that floods have been recorded in every month except for December.

Graph of Floods in Grafton

 

The details of each flood is contained in the below pdf document:

Historical flood peak levels taken at Prince Street gauge, Grafton
 

Flood mitigation

After a series of damaging floods in the 1940s and 1950s, the Clarence River County Council (CRCC) was formed in 1959 to tackle flood mitigation for all the shires of the floodplain. This role has now been taken over by Clarence Valley Council, which was formed as a result of the amalgamation in 2004 of four general purpose Councils and two County Councils of the Valley. 

Prior to the construction of the extensive levee and drain network throughout the Clarence Valley, the devastating effects of flooding drove large numbers of producers out of the valley permanently and denied remaining farmers access to highly valuable agricultural land.

The majority of the early flood mitigation works were rural drains and floodgate structures designed to bring valuable agricultural lands back into production as soon as possible after each major flood event. Areas formerly inundated for weeks or in some cases months, are now drained in a matter of days.

Levee flood protection

The major urban centres of Grafton and Maclean have been protected against major floods since completion of their levees in the 1970s. The $12.5 million South Grafton levee was completed in December 1997. Urban levees have also been constructed at Ulmarra and Iluka. For a map of the Grafton and South Grafton levee system click here.

Levees in urban areas result in tremendous savings to both the government and the community during each major Clarence flood event.

Effects on the environment

The environmental cost of flood mitigation structures has only recently been widely acknowledged. While their existence can never be compromised, Council is increasingly working with the community in managing its structures between flood events for maximum community benefit - and this translates into environmental improvement.

Council is continually seeking solutions to improve water quality in drains and creeks, reviving floodplain watercourses and wetlands, and increasing the diversity and abundance of wildlife. Find out more about the Clarence Floodplain Project and some of the case studies undertaken by Council.

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