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Last Modified: 16 December 2010
Planning
Mangaroa river flood and erosion hazard assessment
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Draft Mangaroa river flood and erosion hazard mapping and design river channelFollowing on from the public meetings, and subsequent correspondence regarding the Flood and Erosion Hazard Assessment on the Mangaroa River, the Greater Wellington Regional Council has prepared flood and erosion hazard maps and a design river channel of the Mangaroa River for consultation. These maps are based on the hazard information that have previously been released.Flood and erosion hazard mapsThe flood and erosion hazard information has been drawn up for planning purposes to ensure that any future development in the Mangaroa and Whitemans Valleys takes into account the potential flood and erosion hazards of the Mangaroa River. The information depicted will be used as a guide, subject to the consultation process, by Upper Hutt City Council staff when preparing a plan change for its District Plan.The flood and erosion hazard map for each individual property or area of interest is attached within personalised letters - mailed to affected parties on 5 January 2010. The maps can be viewed here Design river channelA design river channel has been assessed for the Mangaroa River, which is attached for your area of interest. This design river channel is for the information of landowners to guide any future river management measures.The assessment of the design channel was based on the natural character of the river, taking account of variations along the river. The aim is to determine the boundaries of the active river area (including the channel and a vegetation buffer) under current conditions, enabling more sustainable management of the river. The design channel has been defined using an established empirical process. This is based on changes to the river shown from aerial photography taken over time, and analysis based on the main river-forming influences of flood flows, channel grade (or slope) and bed material (river gravel) size. The alignment has been adjusted to fit the present river channel, taking account of controlling features, which may be more resistant to erosion, such as the valley sides and terrace cliffs. Please note that currently there is no management scheme for the area, and limited funding assistance is available from Greater Wellington Flood Protection for ‘Isolated Works’. Isolated worksGreater Wellington Flood Protection has an annual budgeted amount for a contribution to river works that fit within the Isolated Works policy. Isolated works are privately owned flood or erosion protection works that are constructed outside areas where Greater Wellington manages community flood protection schemes e.g. outside the urban area for the Mangaroa River. The intent of the contribution is to provide a level of service to areas that are not eligible for rate funded community flood protection schemes. The maximum contribution is set at 30% of the actual cost of an eligible isolated work, and has traditionally been provided on a first in first served basis.Contacts for further informationIf you have any other questions regarding this matter please contact Alistair Allan at Greater Wellington Regional Council on (04) 801-1084 or email alistair.allan@gw.govt.nzAlternatively, if you have any questions regarding the District Plan Change process please contact Upper Hutt City Council’s representative, Mike Hurley on (04) 527-2169 or email mike.hurley@uhcc.govt.nz |
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