New Lake Taupo Flood maps show likely extent of 100 year flood

An estimated 1500 properties are within two new 100 year flood hazard zones identified in a study looking at the flood risk around the Lake Taupo shoreline.

 

Maps based on the study findings have been prepared for all of the main settlements around the lake. The maps show an initial “inundation hazard zone” where areas are likely to be covered with water, and a higher “wave hazard zone” where wind is likely to cause waves to push water up onto the land. Many of the affected properties straddle both zones. All properties are affected to varying degrees. In both zones there is a 1% chance that this flood level could be exceeded in any one year (1 in 100 year flood event).

 

The flood study by Opus Consultants has been jointly funded by Environment Waikato and Taupo District Council. The findings in the flood study and a separate study into erosion around the lakeshore are being used as a basis for initial consultation with communities and stakeholders over April and May and will assist with the development of a Lake Taupo Erosion and Flood Strategy. The Strategy will clarify roles, responsibilities and funding and set out a timetable for implementing recommendations.

 

In the meantime legal requirements make it necessary for Council to include the new flood information on Land Information Memoranda (LIM) and Project Information Memoranda (PIM) for affected properties. Letters are being sent out to property owners in the affected areas informing them of the study findings. The flood maps are available online at www.taupo.govt.nz or www.ew.govt.nz. They are also available at Environment Waikato or Taupo District Council Offices and Taupo, Turangi and Mangakino libraries. Anyone wanting to find out about the degree of flooding on a property can contact the Taupo District Council’s Geographic Information Systems Team Ph 07 376 0899.

 

Mayor Rick and Environment Waikato’s Taupo representative Laurie Burdett say the new flood hazard information will allow both Councils to be proactive when it comes to protecting people and property from the risks of future flooding.

 

Mayor Rick said that changes may ultimately be needed to the Taupo District Plan to ensure that development in areas potentially affected by flooding is appropriately managed. While work has only just commenced on what those potential changes could be, Mayor Cooper suggested that they might include things like controlling the floor height or location of buildings. He said the extent of flooding on properties within the hazard zone was likely to vary from site to site. Although it was still early days Officers had indicated that future applications for building or resource consents would be considered on a case by case basis to take account of those variances.

 

The flood study says the extent and depth of potential flooding results from a combination of physical processes (rainfall, run off, lake levels, waves, tectonic deformation, future climate change, seiching*) and human and economic factors (lake level management for hydro power generation, land use change.) *seiching is the slopping back and forth of water in an enclosed basin.

 

The study identifies that the various factors affecting the lake combine in an infinite number of different ways that vary over time to produce different flood levels. The terrain around the lake also determines the extent and depth of flooding from site to site e.g. low lying areas are more susceptible.

 

Final recommendations and actions will be included in a draft Lake Taupo Erosion and Flood Strategy that is due for completion towards the end of the year. Formal public consultation will be sought before the Strategy is adopted for implementation in the 2009/2010 financial year.