Floods in the ACT An information guide

Canberra is a planned city and is well designed with the risks of flooding including response and to deal with flooding, largely due to the early recovery. This does not mean the ACT community adoption of appropriate planning, development should be complacent about the risks of flooding. and engineering standards. While flooding of some land that is normally dry is inevitable we What is a flood? are unlikely to see the nature and severity of flood A flood is defined as the covering of normally dry damage and risks seen recently in other States/ land by water that has escaped or been released Territories. The ACT Emergency Services Agency from the normal confines of a lake, river, creek or and other agencies are well prepared to deal other natural watercourse, a reservoir, canal or dam.

What types of floods can occur in ? There are various types of flood, the two main types that could affect us mostly in the ACT are:

Riverine floods Flash floods Riverine floods occur when heavy rainfall elsewhere Flash floods occur when local flooding due to heavy finds its way down rivers, causing the river levels to rise. rain cannot drain away quicker than it falls. A flash This can happen on any river including the Molonglo, flood is defined by the speed of flooding, notthe Queanbeyan and Murrumbidgee Rivers. This water can source or location of flooding. Flash flooding is typically also back-up into the lower parts of some of the main caused by short duration storms over a localised side creeks, such as Woolshed Creek, Sullivans Creek, area or catchment. The Bureau of Meteorology Yarralumla Creek and . The more describes flash flooding as “Flooding occurring intense the rainfall, the more water converging along within about six hours of rain, usually the result of the rivers. Rain can be falling as far away as Kiandra or intense local rain and characterised by rapid rises in Numeralla in causing flooding along water-levels.” A local example of a flash flood in the the . You may have noticed that “supercell” thunderstorm that hit Woden in January Canberra has not been built close to these rivers – town 1971 where the Canberra Times reported rainfalls planning and engineering standards have significantly up to 100mm in 1 hour were recorded by private reduced our risks from riverine floods in the ACT. rain gauges in the suburbs of Farrer and Torrens.

How prone is Canberra to floods?

Canberra planning has always taken into account are completely immune to flooding. Floods greater How bad have floods in Canberra been in thepast? the need to avoid development in flood prone areas. than the 1:100 year (1%) are possible, and extremely The most notable flood in Canberra The has flooded a Since the 1970’s planning for new urban development intense local rainfall can cause localised flash flooding. was the 1971 event in Woden number of times since Canberra was in the ACT has kept development above the 1% Valley that killed seven people. first established. , which Annual Exceedance Probability (AEP) flood level also Maps showing the 1:100 year (1%) flood line for This flash flood led to major formed , can release known as one in 100 year flood level (1:100). The Canberra are available to the general public on the changes in design standards that water at the rate needed to prevent local stormwater system is designed to cope with the ACT Government’s interactive mapping service have since significantly reduced rises in the water level in the lake for 1:100 year (1%) storm flows through a combination –ACTMAPi website: www.actmapi.act.gov.au our risks from these events. the majority of potential flood events. of piped flows and overland flows. However, no areas

How can I reduce my risk from floods? You and your property may be at some level of risk from flooding. You can reduce this risk through a range of measures including: Where can I get more information?

Preparing your property for flood and reducing the risk to you and • Keeping your property well maintained; gutters, your family downpipes and drains should be kept clear. www.esa.act.gov.au • Make sure children do not go near floodways in heavy rain events. Discourage children from playing in stormwater drains. • Understanding your Insurance Policy. Insurance policies Weather Information – General do not necessarily cover all types of water entry into a Bureau of Meteorology structure/building. You should check the wording of your http://bom.gov.au/ policy to make sure that your cover is what you expect. • Make yourself familiar with things to do during heavy rain, Geoscience including safe driving techniques such as slowing down and http://www.ga.gov.au/hazards/flood.html leaving a greater distance between you and the car in front.

Weather Information – Real time

What should I do if a flood occurs? Bureau of Meteorology http://www.bom.gov.au/australia/flood/ • Monitor ACT local media or the ESA web site • Riverine floods can last for days, so if you (www.esa.act.gov.au) for regular updates. have to cross a river, use a high level crossing. The Bureau of Meteorology web site (www. • Ring 132 500 if assistance is required from bom.gov.au) also carries flood warnings, the ACT State Emergency Service for non-life rainfall information and river level information. threatening situations during storms or floods. • DO NOT drive though flooded creek or river crossings. • Ring 000 if you need assistance • STAY AWAY from floodways and stormwater in a life threatening emergency. drains during storms and heavy rain. • Be patient and stay safe. Most flash floods in the ACT will be short lived – generally less than a few hours.