Moreton Bay Regional Flood Database

Storm Tide Flooding

Version 2.1.0 (June 2015)

This theme shows potential flooding caused by abnormal increases in tide. Strong winds associated with a cyclone or intense low pressure weather system can push a raised mound of seawater, called a storm surge, onto the shoreline. This surge when combined with the astronomical tide and increased wave action is called a storm tide. Storm tide occurs in low-lying locations near the coast.

Methodology

Coastal (offshore) hydrodynamic modelling using a two-dimensional, curvilinear grid provided boundary conditions for the inundation modelling. Inundation from a Storm Tide even was dynamically model (Delft3D) including offshore and nearshore waves and the model included culverts, bridges and drainage pipes. Refer technical publications available from Council's website for further detail.

Existing Conditions Cyclonic Scenario

Modelling a storm tide under existing climate conditions - cyclonic activity.

Purpose

To describe existing flood behaviour during a storm tide caused by cyclonic activity.

Methodology

Coastal (offshore) hydrodynamic modelling using a two-dimensional, curvilinear grid. For this scenario an increase in average wind speed of 10% is assumed. A bathtub approach has been used to extrapolate the model results onto the landward side of the coastline. Refer technical publications available from Council's website for further detail.

Flood Data Notes

Describes the expected reliability of the flood data including indication of specific areas where Council is of the opinion that the data has limited reliability and a reason for this limited reliability.

The notes polygon dataset stores spatial definitions of model areas of known lower data reliability or subject to review.

Modelled Probability

The probability represented by this dataset is:

5% Chance of Flooding in Any One Year

Likelihood: Likely

Annual Exceedance Probability (AEP): 5%

Average Recurrence Interval (ARI): 20 Year

A small flood event that may be observed from time to time. Over a very long period of time an event of similar size may occur on average once every 20 years. Although unusual, an event of this size can occur more frequently. It is likely an event of this size will occur more than once during a single lifetime. The river and creek flood event that occurred in the middle reaches of Burpengary Creek during May 2009 was similar in size to this event.

Version Notes

2.1.0 - TUFLOW modelling with a dynamic Storm Tide boundary (June 2015)

Version Resolution: 2.5m

Data Reliability: A

Indicates the flood data is of the highest available standard and has been prepared using the most recent flood model and input data

Edit History

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Further Information

For additional information on flooding in the Moreton Bay Region please see Council's website:http://www.moretonbay.qld.gov.au/Services/Property-Ownership/Flooding