Decoding Flood Maps: A Guide for Home Buyers

Reviewed by Christina Penrose

We all love a water view, but one aspect that often causes buyers confusion when living by the water is understanding and interpreting flood maps. These maps can be useful tools when considering where you would like to live, but like all tools, they need to be used correctly.

We find that flood maps are a frequent source of confusion, and in this article, we look a little deeper into how to understand flood maps and use them effectively in your home-buying process.

What is a Flood Map?

Flood maps are detailed charts created by various government bodies, like councils or agencies, based on historical data. They provide a visual representation of areas that have flooded in the past.

It is worth noting that historic flooding and potential flood risk are different, and when looking at the flood map reports, one should not be confused by the two. The graphs usually show both, and the map usually shows a potential risk zone. 

In fact, some properties in the zone have never flooded!

What this means for you is that whilst these maps help identify flood-prone areas, additional research may be needed to understand the impact on a specific property. Local flood maps, such as those from your city council, can offer more detailed and specific information about your area. 

For instance, the Brisbane City Council’s Flood Awareness Map provides a comprehensive look at flood likelihood and impact within the city limits. 

Interpreting Flood Maps

It’s essential to remember that flood maps are not infallible; they are based on historical data and do not account for potential changes in weather patterns or human-made alterations to the land. As such, they should be used as a guide. 

Flood maps are usually colour-coded to show different levels of 'flood risk'. The key will explain the colours used on the map and what they represent. 

Using Flood Maps for Property Research

Flood maps serve as an excellent starting point for further research. Here are some tips on using flood maps effectively:

  • Consult local government websites: As mentioned, your city or council will likely have detailed flood maps specific to your area. These can be valuable resources for understanding the potential risks.
  • Get a property survey: A professional property survey can provide detailed information on elevation levels and any potential flood hazards specific to your property.
  • Historical Data: Look at past flood incidents in the area. Understand how often the area has flooded and what impact it had on the property; for instance, did water enter the house? 
  • Flood Mitigation Efforts: Check whether any flood mitigation measures have been implemented since. These can significantly alter the flood risk.
  • Elevation and Topography: Higher elevations are generally safer from floods. Use topographical maps alongside flood maps for a comprehensive view.

Understanding Flood Likelihood and Impact

Understanding the terms 'flood likelihood' and 'impact.' Brisbane City Council uses these terms to explain the chances of floods occurring. Flood likelihood describes the probability of flooding from various sources, such as creeks, rivers, and storm tides.

  • Medium Likelihood (1%): There is a 1 in 100 chance (1% likelihood) of flooding occurring in any year. This type of flood is considered irregular.
  • High Likelihood (5%): There is a 1 in 20 chance (5% likelihood) of flooding in any year. This type of flood is considered regular.

The Importance of Being Informed

Flood maps are valuable tools when researching properties near water sources. However, they should be used as a guide alongside other research methods, such as property surveys and historical data analysis. Understanding flood maps is more than just a box to tick off your home-buying checklist; it’s a critical step in your property research.

Feel free to reach out to us for more information.