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Last Modified: 10 April 2012
Mangaroa river flood and erosion hazard assessment
Flood and erosion hazard maps
| Maps of the proposed plan change are provided below. An explanation of the different areas defined on the maps is described below: |
| River corridor The river channel and adjacent berm land subject to flooding and erosion by the river, based on river processes and local topography. It is the minimum area able to contain a major flood and pass the flood waters down to the sea. It includes flood and erosion prone land immediately adjacent to the river, where there is a high risk to people and assets. Overflow path Floodplain areas adjacent to the river corridor where overland flows from flood water can occur in flood events. Erosion hazard and building setback: A wider area of land alongside the river, which is potentially at risk of erosion from the Mangaroa river. Ponding: This is the area where slower-moving flood waters may pond either during or after a flood event. The area identified as ‘ponding’ is expected to be affected by a flood event with a one in one hundred (1%) chance of being equalled or exceeded in any one year. On average this event is expected to occur once in 100 years, based on past flood records, but in reality it could occur at any time. |
Hazard Maps |
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