Topic: Sand - Rapanui North

Topic type:

RAPANUI NORTH

 

 

 

Rapanui North is south of Te Kawau Pa.  It is separated from Te Kawau Pa by an impassable stretch of coastline.  Rapanui North is located on the northern side of the Rapanui Stream.  A small dune area is located on the northern side of the Rapanui Stream and it culminates just short of the main highway.  There is a grassy picnic area that separates the dune from the road.

 

I haven’t as yet really documented this dune.  It is shown in cliff sequencing images, but this is more by just being there, than a conscious effort to record it.  This is something I plan to correct from 2010.  The dune is well clothed in marram grass, lupins and flax plants for the most part.  There was also a good population of bullrushes, these being more to land-ward.

 

The dune area is also replete with beached logs.  These form the scaffolding for the seaward side of the dune.  They also extend internally (covered by sand) for some distance, acting to hold the sand in place.  That, along with plant roots, helps to keep the dune relatively stable.  Its sea-ward edge is prone to wave induced erosion.  Equally, when the sand level builds back, the dune can advance.

 

Under normal storm/fine weather cycles, the dune retreats and advances in accordance with these cycles.  Thus the dune exists in a state of balanced equilibrium.  This is true of all the dunes on the Tongaporutu coastline.  However, there is a caveat to this.  If the sea levels are rising, then the growth/retreat parameters change.  The dune retreats faster than it is able to grow back until ultimately the dune is destroyed.

 

Aside from this smallish dune, there are up upper dry beach areas at Rapanui North.  High tides come right up to the cliffs.  Rapanui North beach travels a short distance north before turning to seaward at the base of a large, impassable bluff.  This extends too far out to sea to pass.

 

 

 

2003

 

 

26.10.2003   PHO2008-323-324

 

Though I was CLIFF SEQUENCING at Rapanui South Beach, the two images shown here look across to Rapanui North Beach.

 

 

4.11.2003   PHO2008-354, 368-371, 373

 

CLIFF SEQUENCING.  It was a cold, sunny day with a very strong westerly wind.  There were lots of logs hanging around the dune area.  Between the river and the dune, there were two sand platforms of different heights, with the platform closest to the stream being the lowest.  The dune is set further back to land than the low (in height) cliffs that march along to the north.  The sea was chopped up and there was a lot of flying salt foam.  The beach was well endowed with sand, but there were pockets of rocks, some housed in froth-laden pools.

 

In roughly the middle of the beach leading down from the dune, there was a small, shallow V formation.

 

 

 

2008

 

 

15.12.2008   PHO2011-1472, 1474

 

CLIFF SEQUENCING.  The day was dullsville with wall to wall cloud and a light drizzle.  Though this was cliff sequencing, it wasn’t as thorough as the original cliff sequencing done on 4.11.03.  This was because of the tide height plus choppy conditions.

 

Down at the wave-line near where the Rapanui Stream empties into the sea, it appeared as if the dune had been pushed a long way back to land-ward.  The sand was well built up at the cliff bases, although some rocks were visible.  The section of beach before the dune proper had built up into a well defined shelf or platform.  In the middle of the beach, a cluster of round rocks inhabited a shallow depression.  This is the site of the V formation.  Today, it was almost completely filled in with good sand cover.

 

 

 

2010

 

 

18.9.2010   PHO2011-1836, 1838-1839, 1842, 1845

 

MEGA-STORM.  As I could only photograph with the digital camera due to the appalling conditions, I photographed at as many places as I could.  The purpose being to record this rare, record breaking event.  At its peak, this was the biggest storm on the planet.  Luckily, we were spared the worst of it, in part due to it coinciding with a low high tide.

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