Matata LIDAR 1m Contour Ohinekoao
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The scheme concept is to provide a stream channel for flood flows (and some debris), while reducing the height on the stream bank so that future debris flows can flow over the bank and towards the road and railway without significant obstruction. The path towards the campground will be blocked by adding to the earth buttress placed after the May 2005 event. The extended buttress will be constructed to contain the expected level of debris in an event to May 2005.
On the fanhead, seaward of the railway and the highway, a debris bund will be constructed to prevent flow towards the campground as the debris flood spreads out on the flatter terrain. The works include:
• Excavation of material from the right stream bank downstream of the escarpment to reduce the height and clear a path for future debris flows
• Placement of material to increase the height and extent of the existing earth buttress on the right bank of the escarpment and form a debris control bund to direct the path of future debris flows
• A bund on the coastal flood plain to limit generally the extent of future debris flood spread to the left of the fanhead
• Gabions to stabilise the stream banks and provide erosion protection in the reach flowing to the State Highway culvert
• New twin 5 m by 2 m high box culverts under the State Highway