Brisbane Floods & The Importance of Surveying

Unfortunately Brisbane and South East Queensland were hit by yet another flood in January 2013. Although not quite as destructive as the 2011 floods, many properties were affected and many people seriously concerned about the possibility of this happening again. This event illustrates changes in weather patterns and with this, the importance of protecting your land and property by getting the necessary surveys done. Here are some surveying services we provide which will assist you with the planning and development of your property.

Determining The Height Above Sea Level For Your Land

If you were not aware, when the authorities release statistics on how high the different rivers are peaking during a flood (e.g. Brisbane river to peak at 2.5 metres) this is in relation to the height above sea level. This will give you some idea of where the displaced water will end up in nearby suburbs to that river.

To ensure that you can use this data to find out whether your property may flood or not, it is necessary to know the elevation of your land above sea level. We can help provide you with a detailed report for this by doing a topographic survey of your land and the buildings contained on it. Having this information will help give you a better idea if your property is going to flood from the expected river peak levels. This is particularly important if you are planning to build or raise your house. If you are currently involved in designing a new house or you are raising a building to avoid flood waters, then now is the time to consider your land’s drainage and relation to AHD levels.

Flood Maps

This same information will also help you more accurately read the flood maps produced by the local councils. If you know how high your property sits above sea level, you can reference this when viewing the flood maps that are released to more accurately determine if you are in the firing line.

Height Certification Amended to 9.5 metres in Flood Prone Areas

Recently the Brisbane City Council increased the maximum height allowed for the roof of a residential house from 8.5 metres to 9.5 metres. This change is one of a number of changes proposed in the Draft City Plan. This applies to those areas of the city which were affected by flooded creeks or Waterways and/or the Brisbane River Flooding. This means any new buildings or extensions to previous structures now may be raised and certified to a maximum of 9.5 metres.

Flood Study Surveys

Local authorities require all development of land to be above the 1 in 100 year flood level. To determine this level, the topography of the land must be surveyed and used with the volume of the catchment to determine the Q100 level relative to the Australian Height Datum (AHD). With the current weather extremes, this is very important to consider before starting any new developments or before you purchase a new property. If you are unsure please contact us and we can help establish the Council requirements and Q100 levels applicable to your property.

The 2013 Brisbane flood map showing prone areas