Appendix F & Appendix G

261 Pages·2017·11.68 MB·English

Appendix F: Technical reports
 Ecology
 Coastal process
 Landscape
 Archaeology
 Cultural Impact Assessment
Coastal Assessment
Prepared by Richard Reinen-Hamill, Coastal Engineer, BE, ME, FIPENZ

1 Overview
This section provides a description of the coastal effects assessment for the proposed transportation
infrastructure (both Road and Rail) along the coast north of Kaikoura. The assessment is done in
accordance with the NZTA (2017) guideline for coastal effects assessments, which aims to inform
decision making in a risk management context.
2 Coastal environment
The road and rail corridor is located between Goose Bay south of Kaikōura and the Clarence River on
the north-eastern coast of the South Island. The transportation corridor follows the coast and is
bound on the east by the Pacific Ocean and on the west by the steep ranges that extend along the
coast from Oaro to just north of Okiwi Bay (refer Figure 1). These ranges are interrupted by the
fluvial plains adjacent to Kaikōura and the Clarence River and have a variety of low standing coastal
landforms intersecting them. This includes several small streams and gullies traversing the ranges
conveying local catchment dischargers to the coast.
The Kaikōura Peninsula environment is subject to highly energetic processes in terms of both marine
and weathering processes. Shore platforms are exposed to the dominant wave directions and are in
the intertidal zone. It is exposed to an extremely long fetch from the Pacific Ocean characterized as
a high-energy oceanic swell environment, with high-energy storms interrupting long periods of
relative calm. High-energy storms due to the passage of cyclonic depressions over New Zealand can
occur at any time of the year.
Consequently, both marine erosive forces and sub-aerial weathering processes contribute to
erosion. Shore platforms (up to 30 metres depth) range from 40 m to over 200 m wide and are cut in
Tertiary aged mudstones and limestones. The shore platform extends to variable drop rapidly in the
canyon features of 1 – 1.5 kilometres.
2

Figure 1 General topographic features and bathymetry along the coastal road and rail route from Oara to the
Clarence River (Source: LINZ Hydrographic chart)

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3 Describing the assets and activites
The damage to the road and rail network as a result of the Kaikōura earthquake requires significant
works to restore the function of both networks. While repairs to most of the route are able to be
undertaken on land, there are certain areas where repair works will result in encroachment of the
transport corridor into the Coastal Marine Area. This occurs in areas where there is typically steep
cliffs that will have significant and ongoing landslide risk to construction activities including health
and safety risk to construction crews as well as risk of ongoing resilience / operation requirements of
the transport network.
The alignment of SH1 and MNL will remain on their existing alignments, except at:
 Rosy Morn Marine Reserve Area 1 and 2
 Site 29 A
 Site 1
 Sites 2, 6 and 7 (revised footprints)
 Site 3, 4 and 5
 Sites 8 and 9 (new footprints).
3.1 Proposed works
The significant majority of works in these areas are located landward of the new mean high water
springs (MHWS), which has shifted in a seaward direction as a result of uplift following the
earthquakes. Notwithstanding this, some works are located in close proximity to and sometimes
within the coastal marine area (CMA) and involve varying degrees of reclamation and occupation.
The general description of the activities and restoration works for NZTA and KiwiRail in included in
the AEE for the works (refer Drawings in Appendices B-E of the AEE). The main structural
components of the proposed works are:
i Vertical concrete seawalls anchored to the rock reef
ii Composite wall comprising a vertical seawall protected by a rock armour toe, and where
existing beach sediment is available under the proposed road footprint, that this material is
excavated and placed seaward of the structures to effectively relocated the beach to form a
natural system in front of the walls.
iii A sloping rock armour revetment, and where existing beach sediment is available under the
proposed road footprint, that this material is excavated and placed seaward of the structures
to effectively relocated the beach to form a natural system in front of the revetment.

All works have been designed taking into account the present day geological hazards, coastal
processes and forces for construction and long-term resilience needs, sea level rise predictions and
landform setting/ visual impacts, using the following design philosophy:
 Limit encroachment of protection structures seaward of the present day Mean High Water
Springs (MHWS) where practicable.
 Provide erosion protection to the road and rail corridor to withstand a 100 year joint probability
extreme wave and storm surge event inclusive of an additional 0.51 m sea level rise as a result of
climate change.
 To limit overtopping discharge to the road rail corridor to less than 5 l/s/m during a 50 year wave
and surge event inclusive of 0.51 m sea level rise.
 Retain existing beach form, including beach cobbles, gravels and sand seaward of proposed
erosion protection structures.

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 Consider the potential for an additional 0.52 m sea level rise (i.e. a total of 1.03 m sea level rise
from present day levels) and the requirement for adaptation responses could be accommodated.
 Maintain or enhance access to the Coastal Marine Area at selected areas along the route.
Where practicable, any hard engineering should mimic the coastal form and character. The
construction phase should be managed to ensure that any high energy events do not compromise
the activities.
3.2 Construction process
A Construction Environmental Management Plan (CEMP) will be prepared for the works, to manage
the potential effects of the construction activities. The construction process as it applies to the
coastal environment includes the following activities:
1. Excavation and transfer of existing beach deposits further down the beach/reef face to
prepare subgrades and foundation levels for coastal protection structures. This would largely
be done by hydraulic excavators and other earth moving machinery and initially the material
would be placed to form a bund to protect the works area from possible wave action while
construction activity took place and then redistributed to form a sloping foreshore in front of
the protection works.
2. Excavation and works to prepare foundations into the rock reef platform. This would be done
by large hydraulic excavators to rip the upper layer of weathered rock and to move existing
boulders to form the foundation connection on the rock reef. Excavated rock material would
be used as part of the fill while existing boulders would be moved to the seaward side to be
retained on the foreshore and reef top areas.
3. Concrete works and formation of the vertical wall foundations and importing and placing
vertical seawall units.
4. Placing the rock armour for toe protection works.
5. Machinery and access for works on the upper beach and reef areas within a 5 m wide corridor
seaward of the toe of the protection works. While much of the work will be carried out from
within the construction footprint, some machinery will need to operate on the seaward side of
the proposed works. This will by typically on the upper beach/reef area and away from the
wave run-up zone. At Site 6 (Ohau Point), this corridor is likely to be affected more regularly
by wave action at high tide and access is likely to be restricted around this point during
onshore wave events at high tide. Restrictions may be required at other sites, but it is
expected to be required less frequently.
4 Describing the environment
The shoreline along the transportation route can be characterised as rock foreshore with numerous
headlands, platforms and points which create small enclosing bays (Boffa Miskell, 2012) often the
location of small creek outlets or gullies. The main geomorphic features in this area are the steep
Kaikōura Ranges that the steep ranges that extend along the coast from Te Ikawhataroa Point to just
north of Okiwi Bay and are bound by the fluvial plains adjacent to Kaikōura and the Clarence River.
The fluvial plains adjacent to Kaikōura are formed from sediment discharges from the Kahutara,
Kowhai, Hapuka and Puhi Puhi Rivers.
4.1 Topography and bathymetry
The ranges extend up to 1100 m in this area, although along the coastal route more typical
elevations of the peaks are between 400 to 540 m. There is a very narrow shelf of eroded rock reef
platform before depths reach 10 m below Chart Datum as shown on Figure 1. The seabed slopes

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gently (100H:1V) along the continental shelf from the 10 m to 130 m contour before rapidly reaching
depths of more than 3 km along the Hikurangai Trench (refer Figure 1).
The 130 m depth corresponds roughly to the level of the sea during the last glacial maximum 20,000
years ago, when massive ice sheets locked up large volumes of the planet’s water. The
progradational surface deposits of the shelf are 1–1.5 km thick, having accumulated since the mid-
Quaternary, 24 million years ago. Underneath this deposit lie shallow marine sediments up to 138
million years old, from the Oligocene to the Late Cretaceous, above Permo–Jurassic greywacke up to
280 million years old (Herzer, 1979).
4.2 Coastal sediment
The coast between Goose Bay and the Clarence River mouth is generally steep slopes and eroding
cliff and shore platform cut largely in Pahau terrane rocks (Rattenbury et al. 2006), composed in part
of greywacke and in part of Tertiary sedimentary rocks. With the exception at Kaikōura, rivers and
streams flow to the ocean out of incised valleys. The smaller rivers and streams that drain the
coastal ranges are typically found ponded behind gravel barrier beaches. At Kaikōura the rivers flow
to the ocean across steep alluvial fans. The longest beaches are the barriers of mixed sand and
gravel fronting the alluvial fans on either flank of the Kaikōura Peninsula.
Kirk (1985) identified the shore configuration between the Hapuka River and Okiwi Bay were
dominated by high wave energy – a function of the direct exposure to the Pacific Ocean and the
narrow, embayed continental shelf which focusses wave energy and minimises wave energy losses
by sea-bed friction. The shores consist of narrow wave-cut shore platforms and offshore reefs that
are the eroded remnants of former shore platforms. Debris from the erosion of the shore-platform
are transported into the small pockets and embayments and tectonic uplift has played a role in
preserving some of these deposits.
The main sediment source for these coasts are from erosion from the reef, shore platform and
backshore deposits and this is supplemented by coarse sediments from streams and landslides from
the catchment. There appears to be a delicate state of balance between sediment supply and
dispersal by the high wave energy (Hicks, 1988).
4.3 Currents
This section regarding the larger scale currents operating off the Canterbury coast is taken from Hart
et al. (2008).
Canterbury’s diverse continental shelf and coastline are strongly influenced by the position of New
Zealand at the crossroads of at least five major oceanic water masses. The ocean’s top 200 m
consists of the warm, saline and nutrient-poor Subtropical Surface Water (STW) in the north, and the
cold, less saline but more nutrient-rich Sub-antarctic Surface Water (SAW) in the south. Vertically
stacked in the deeper waters beneath are the Antarctic Intermediate Water, Pacific Deep Water and
Bottom Water (refer Figure 2).
The locations and extents of these important water masses are not fixed but, rather, move around
both seasonally and from year to year, with mixing occurring across their boundaries. After heating
up in the central Pacific, the STW flows south along the east coasts of Australia and New Zealand in
the form of the East Australian Current and the East Auckland Current. The latter current gives rise
to the East Cape Current, which flows south along the eastern North Island to a transition zone off
Canterbury. This forms part of the global Subtropical Front (STF), a large and continuous
convergence zone where the warm STW meets the cold SAW moving north from the Southern
Ocean. The STF stretches south of Tasmania across the Tasman Sea to southern New Zealand,
where it occurs between 40 and 45°S (refer insert Figure 2). Locally referred to as the Southland

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Front (SF), it wraps around the eastern South Island from Stewart Island to just south of Kaikōura,
and then is diverted out across the continental shelf (refer Figure 2).

Figure 2 Major ocean current systems along the east coast of central New Zealand (Source: Hart, et al 2008)
Here it follows the 15° and 10°C isotherms in summer and winter respectively, corresponding to
waters with 34.7 and 34.8 parts per thousand of salt. Since marked changes in temperature and
salinity take place within the water column, the exact geographical location of the front varies from
season to season.
Oceanic circulation close to the coast is shaped by the interaction of surface- and deep-water masses
with the coastal and offshore bathymetry, shallow wind-driven circulations, and the tides. The tidal
wave first approaches the south-west coast of the South Island of New Zealand. From there it travels
through Foveaux Strait and north along the east coast of the South Island for about two and a half
hours to Banks Peninsula, reaching Kaikōura after a further hour. The tidal regime is semidiurnal,
with around 12 hours 34 minutes between successive high tides.
4.4 Tide and extreme water levels
Level information is available in NZVD-2016 NZVD, Lyttelton Vertical Datum (LVD-1937) and
Lyttelton Chart Datum (LCD). LVD is 0.389 m below NZVD (i.e. add 0.389 to NZVD values to convert
to LVD). LCD is 1.15 m below LVD or 1.539 m below NZVD.
4.4.1 Tide levels
Based on the nautical tide level predictions at Kaikōura the spring tidal range is 1.8 m with the neaps
range of 1.1 m. Table 1 shows the high tide levels for a range of parameters at Kaikōura. The MSL
here is in relation to LVD. These levels can be considered representative of Ohau Point.

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Table 1 High tide parameters at Kaikōura (Source: Mulgor, 2010)

For the definition of MHWS, we are proposing to use the high water spring condition that is annually
exceeded by 10% of high tides (i.e. MHWS10). At this location MHWS10 = 0.84 m + 0.189 m = 1.029
LVD (NIWA, 2015), i.e. 0.64 m NZVD. The adjustment of 0.189 m is to take into account the change
in mean sea level from the time LVD was established (1937) to the present decade (Stephens et al.,
2015).
4.4.2 Extreme water levels
Extreme water levels that combine storm tide and tide levels have been assessed along the
Canterbury coastline by NIWA (2015). They assessed storm tide, wave set-up and run-up at 29
locations and provided information in terms of LVD.
Extreme water levels for Kaikōura:
5% AEP Storm tide (from Table 6-4, NIWA 2015) = 1.37 m + 0.189 m = 1.56 m LVD (1.17 NZVD)
1% AEP Storm tide (from Table 6-4, NIWA 2015) = 1.43 m + 0.189 m = 1.62 m LVD (1.23 NZVD)
Note these levels are based on simulated extremes. Gauge data suggests could be around 7 cm to 9
cm lower.
4.5 Wave climate
4.5.1 Offshore wave height
The offshore annual wave climate is reasonably uniform along this stretch of coast. A wave rose
from hindcast modelling is shown in Figure 3 and wave height and period frequencies shown in
Figure 4. This information is from wave hindcast data from MetOcean Solutions. Figure 3 shows the
majority of wave energy coming from the south east with smaller amounts from the east. Figure 4
shows that waves are less than 0.5 m some 23% of the time and for around 65% of the year
significant wave heights are between 0.5 and 1.5 m in height. Wave heights are generally less than 3
m apart from during onshore storms. During these events wave heights can exceed 6.5 m with a
peak period of 13 seconds. Extreme event analysis carried out by MetOcean Solutions shows the 10
year return period wave height of 5.8 m and a 100 year return period wave height of 7.2 m. The
maximum offshore significant wave height is in the order of 10 m.

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Figure 3 Annual wave rose (Source: MSL database)

Figure 4 Peak period vs wave height from MSL database
Extreme wave conditions and the combination of extreme waves and storm tide has also been
carried out by NIWA (Stephens et al., 2015). They calculate the 10 year return period wave height to
be 5.77 m and a 100 year return period wave height to be 6.48 m for the maximum likelihood, with
the 95% confidence interval of 7.59 m for the 100 year event. These are similar to the estimates of
MetOcean Solutions. NIWA give joint probability for the significant wave height (Hs) and storm tide
level relative to MSL at Location 3, north of Kaikōura (refer Figure 5). The site closest to the project
area is included as Figure 6. Their assessment included a fit with their hindcast data and a 1.5x
scaling to take into their modelling under-predicting extreme wave heights at Banks Peninsula.
Comparing the information from MetOcean Solutions and NIWA, the range of possible extreme

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wave heights are similar, with the predictions of return period by MetOcean Solutions bounded by
NIWA’s initial assessment and their scaled assessment. Our approach is to use MetOcean Solutions
predicted wave heights as an initial step but to use the scaled joint probability lines of NIWA to
evaluate the combination of wave height with water level.

Figure 5 Location of wave output points (Source: NIWA, 2015)

Figure 6 Joint probability of significant wave height and storm tide at JP3 north of Kaikoura (Source: NIWA,
2015) with the blue lines showing the match with data and the red lines showing a 1.5 x scaling adjustment.
Water level datum LVD-37
Therefore a 1%AEP significant wave height (H) of 7.2 m and storm-surge level of 1.25 m + 0.189 m =
s
1.44 m LVD) is a reasonable design condition for a 0.5%AEP event offshore. While higher waves are
possible, this combination would be with a lower water level.
Based on Figure 4 the Wave period for 6-6.5 m waves 13-14 seconds (i.e. around 2% wave
steepness). Use 3% to 4% wave steepness for establishing period for 7.2 m wave (i.e. storm
conditions) means similar wave period (i.e. around 13 seconds).
4.5.2 Nearshore wave heights
Nearshore wave height and water level information were assessed using a number of different
techniques, including:

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