Disclaimer: Nearmap provides this flood information as a general reference source only – it is not intended as a flood risk assessment and should not be relied upon as such. The flood information provided has not been prepared by taking into account your specific circumstances and/or purpose and may depend on statistical models and assumptions which may be incomplete or wrong, negatively impacting the accuracy of the flood information. Before relying on any flood information, you should independently verify its accuracy, currency, completeness and relevance, and obtain any appropriate professional advice relevant to your particular circumstances and purpose.
The flood information provided is current as at the publication date only and, as a Product under the Nearmap Agreement, is subject to the limitations of liability and other terms set out in the Nearmap Agreement.
How the model works
Nearmap collects elevation data as part of each aerial survey. This uses new technology so the elevation data is only available for recent surveys.
The model itself is very simple. The user is able to provide a water depth level above sea level. This water depth level is then used to render a layer which overlays the terrain.
In practice this means the Flooding Layer shows a potential flooding scenario based on the assumption that water levels are consistent across the modeled region (represented as a flood level above approximate sea level).
The model works very well in simple topographical areas, such as flood plains. See the images below for a comparison of modeled flooding to an actual flood in Bundaberg. However, in more complex terrain the model will be less accurate and therefore less reliable.
Actual flood imagery
How to use the tool
Flooding is part of the Data Layers tool and accessible on most Nearmap subscriptions. The tool is not compatible with certain older web browsers such as Internet Explorer 9 and below.
Only certain areas of recent surveys will have flooding data available. Elsewhere, you'll see a "Data unavailable, please select another date." message appear. This will also occur if you zoom in past the level at which the scale bar size is 20 m or 100 ft.
Click Show Flooding to turn on the layer. The Water Level setting is in reference to meters above sea level, so if your area is quite elevated you may not see any flooding shown at all unless you set this number above local elevations.
Check the depth shading checkbox if you would like your flood area shaded based on the depth of the underlying terrain. You can adjust your floodingColor to blue, green, red, yellow, or the brown option, which is close to photorealistic.
Sources of error and uncertainty
It is also important to note that the model does not capture much of the complexity of water flows and terrain in the real world. More specifically, the sources of uncertainty include:
The terrain elevation data used by the Flooding Layer may vary from the actual elevation at any given location.
The Flooding Layer does not consider any specific surface hydrology (e.g. water velocity, supercritical flows, rainfall accumulation).
The Flooding Layer does not consider any specific sub-surface hydrology (e.g. interaction with sub-surface features such as storm water systems, underlying geology, groundwater).