How to Use Online Sea-Flooding Mapping Tool For Thames-Coromandel

What is the Coastal Inundation Tool?

The Waikato Regional Council has provided a very useful online sea-flooding / inundation tool on its website.  The purpose of this tool is to see what low lying coastal areas in Thames -Coromandel may be subject to inundation (sea flooding) from tides, storms and projected sea level rise. The tool uses a “Google maps” type system allowing the user to zoom in on a property, suburb or town and view various sea level rise and storm tide scenarios.

The tool only shows ‘static’ water levels.  It does not include the effects of currents or waves which may add to the flood risk, and is indicative of flood levels. 

 Step 1    Go to Website

 

Step 2    Zoom in to Area of Interest   

Zoom in by choosing a region from the top right corner – eg. Firth of Thames, East coast or West coast. Or double click the map or use the + or – buttons.

Step 3    Choose Water level  

Click on the “Pre-defined water levels” button in the left-hand column.  Then choose the region and sub region you are interested in.  eg. Firth of Thames / Thames Tararu.  Tidal and storm tide levels vary between regions/towns so it is important to select the area you are interested in.  A pop up a table will appear, but make sure you choose the right region and sub-region – (this one is for Thames/Tararu) –

Step 4    Choose a Scenario from the Table.

In the Pre-defined Table, you are presented with 3 scenarios – 

• Present Day,
• Future Projected 0.5m of sea level rise, and
• Future Projected 1.0m of sea level rise.

Within each scenario you can then choose

• Mean High Water Springs (MHWS),
• Maximum Tide (“King Tide”), or
• a Low or High Storm Tide. 

Storm Tide or Storm Surge: this may occur when a low-pressure system causes the tide/water to rise and onshore winds ‘push’ water from deep water towards the coastline. eg. Cyclone Drena in 1997 which caused serious sea flooding in Thames.

eg. for a “Low” Storm Tide and 0.5m of sea level rise for Thames you would choose 2.70m from the table above.  

Storm Tide Frequency

The Parliamentary Commissioner for the Environment has reported that extreme “1-in-100-year” storm tides will occur every 6-12 months with just 0.5m of sea level rise and daily with 1m of sea level rise.  Therefore it would be wise to look carefully at the storm tide levels when using the tool.

Step 5    Move the Slider to Chosen Water Level

Move the slider to the nearest match of your chosen water level and explore by zooming in and out and moving the slider to other water levels if required.

More Information – FAQ

More information and answers to questions here

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