Part 1 - Palmerston North City Council

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Some 400 metres of the 55 metre high cliff face is actively eroding. An unnamed tributary (from the valley
between Cashmere and Waicola Drives) dissects the actively eroding part of the cliff into two parts; a
western cliff and an eastern cliff. The Mangaotane Stream (also known as Bryant's Creek) running from
Moonshine Valley joins the Manawatu River just upstream of the eastern cliff.
Much of the land directly above the western cliff is residentially zoned and lies between ANZAC Park and
Pari Reserve. The land is accessed from Vaucluse Heights. Some of this land has been subdivided with a
couple of dwellings already constructed at the Cashmere Drive end of Vaucluse Heights. The balance of
Vaucluse Heights, although formed, is in private ownership and does not have public access at this stage.
The land above the western cliff is being eroded and lost at an increasing rate. The cliff itself presents a
safety risk in the area, and while it has been fenced off in the past, the cliff is now slipping away beyond the
fence and constant repairs and adjustments to the fence are required.
ANZAC Park is located just west of the actively eroding cliff. This park is accessed from Cliff Road and
contains remnants of the 90 Mile Bush, a Tangata Whenua site (Te Motu o Poutoa pa), the Manawatu
Observatory and a car park. It is colloquially known as "Pork Chop Hill". The Te Motu o Poutoa pa is
recorded in the New Zealand Archaeological Association’s site recording scheme as Site T24/20. The cliff
below ANZAC Park still retains vegetative cover and is not actively eroding to the same extent as the subject
cliff.
The eastern cliff is mostly contained within the Pari Reserve however the top edge of the cliff has now
retreated beyond the reserve and is starting to erode the privately owned residential land that is located off
Waicola Drive. Further upstream of the eastern cliff the left bank of the river is lined with a strip of dense
vegetation (predominately willows and poplars with a mix of other exotic weed species interspersed
throughout) with farm land beyond.
At the site where the MWRC proposes to carry out the works the Manawatu River runs directly into the
base of the ANZAC Park cliff and is forced to make a sharp right hand turn. The flow of the river directly
into the cliff is undermining the base of the cliff and causing continual slips from higher up.
A large gravel beach has formed on the inside of the river bend and there is a grassy area between the
beach and the Esplanade Walkway. These attributes, along with the ready access to the City, make the area
popular for recreational activities, especially during summer.
3 THE PROPOSED ACTIVITY
The MWRC intends to realign the Manawatu River so that it is directed around the ANZAC Park cliff bend
without causing further erosion. This will take several stages to complete but when finished one will see
that the river takes a gentler curve and will be located near the position it was in 1992, being closer to the
right bank. A rock lining on the left bank will direct the river around this curve and a snub groyne will be
visible a short distance upstream of the rock lining. River gravel will be backfilled and compacted behind
the rock lining and the bed of the river will be armoured to protect it from scouring and erosion. The
unnamed tributary will be extended so that it flows through a gap in the upper portion of the rock lining
and the Mangaotane Stream will be realigned so that it joins the Manawatu River upstream of the snub
groyne.
Engineering drawings of the proposed works are attached to this report as Appendix B. Figure 1 shows an
overview of the site with the proposed layout of the rock lining, snub groyne, bed armouring and the
extension and re‐alignment of the small streams in the locality. It is noted that the aerial photograph used
in this figure was taken on 26 January 2011 when the river level was at least 1.7 metres above typical low
flow. Figures 2 and 3 show typical cross sections of the proposed river channel and rock lining, and Figures
4, 5 and 6 show details of other components of the proposal.
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