Flood Plain Mapping

The floods in 2004 were some of the largest in the Manawatū-Whanganui region in recent times. Post-flood analysis identified gaps in knowledge concerning flood risk. To address this, a flood mapping project to identify and quantify the extent of flood hazard was initiated. This five year project saw significant investment in data acquisition for flood modelling to better provide information to the public and protect people and property.
 
A series of flood models were developed where key risks were identified, with various annual return intervals (ARIs). Those presented here have a probability of 0.5, meaning that in any given year there is a 1 in 200 chance that it may occur. These models represent a snapshot in time. Subsequent changes to land forms on the flood plains (drains, berms, etc) will affect the utility of these models.
 
Horizons has completed flood modelling for some of the region’s catchments where key risks were identified. Please note that not all catchments have been modelled due to cost restraints.  In the areas that have had 1 in 200 year flood modelling completed, the flood extents have been added to the flood plain map.
 
Important: The flood information provided only shows river flooding and does not show all the areas that might get wet during an extreme rainfall or flood event. Areas of ponding from stormwater and other overland flow sources are not included in the model output, and the modelled extent may not cover the full flooded area for a given event. The intended use for this information is as a planning tool and must not be used in isolation. Consultation with Coordinator District Advice at Horizons Regional Council is required for advice at a property level for flood hazard.
 
The information presented here is a cartographic representation; features shown may not be in their true location. More detail than is presented here is available on request from Coordinator District Advice, Horizons Regional Council.
 

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1. This website and the information provided in it are the copyright of Horizons Regional Council. This website is a public service and may be used for personal and business purposes. Users are not permitted to copy or republish any substantial amount of the information from this website without the prior written consent of Horizons Regional Council.
2. Use of information from this website is entirely at the users own risk. Due care has been taken in providing the information on this website. All information should be considered as being illustrative and indicative only.
3. Horizons Regional Council does not give and expressly disclaims any warranty as to the accuracy or completeness of the information or its fitness for any purpose.
4. Horizons Regional Council accepts no liability for any error, omission, or inaccuracy of the information or from any use of or reliance on the information provided by this website.
5. The user should independently verify the accuracy of any information before taking any action in reliance upon it, i.e. any feature shown on a plan should be physically verified on site prior to any design, construction or other works taking place, property boundaries should be verified by a qualified surveyor.
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District Advice Requests

Please use our online form to log any new District Advice requests. Search the property details by entering the residential street address, e.g. 11 Victoria Avenue (please don’t include the town/city) or search by the valuation number, e.g. 14610 828 00. There is a ‘searching time’ icon in the bottom right-hand corner of the webpage that shows the length of time to locate the address. Please provide the purpose of your request and attach or drag and drop any relevant documents. We aim to get back to you within ten working days.