Beating off the waves – Sinking or migrating?

It opened up new views of the Maldives to me.  The story of how they were fighting off sea level rise was a familiar one to me – I even had worked on a project at university in the 1980s exploring the various options.  My solutions there had been rather clunky – using material from the inside of the atolls to build up the outside, more sea defences, different land uses.  Now I was here I could see that all of these had been tried and more.  But my view was that every island was the same and uniformly affected by sea level rise.  What I now saw was that while there was that inexorable pathway to submergence from sea level rise, the short term effects of that were affecting one side of the island more than the other.  Having a small amount of rise might not impact the coast, but if a storm came in, the accumulation of larger waves on top of an incremental change in normal levels could be devastating for a vulnerable coastline.  And that is what I had seen on the eastern side of the island.  When the sea is benign there is not issue, but if a storm hits serious erosion can happen overnight – especially if trees topple and the loss of roots shakes free lots of sand and soil.

But what appeared to be happening is the island is migrating.  Much of the material that was removed from the east was migrating round to the west, and the island is gently moving towards the centre of the atoll.

The long term dynamics must be more complicated that this and it might take many generations for the island to move a long way, but it was undeniable that most of the slack, the dune and the beach were relatively recent additions to the coral island.  The upshot is though that given the small size of these islands and some with a high population density, there is not enough room for leaving the usual setbacks that minimize damage to property in storms.

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Is the island stable, eroding or migrating?

Beating off the waves – Where the waves hit hard

We held our meeting and heard the views from the local council members.  There was a lot of detail but one thing that was drawn to our attention was that one side of the island was being affected much worse than the other.  We had agreed that we wanted to survey the whole coastline of the island and we thought that seeing the issues was better than talking about them.  The chiefs of the village council came along with us and we first targeted the coastline that was most under threat.

As soon as we stepped onto the rocks on the eastern side, the problem became apparent to us.  This was the most exposed part of the coast; beyond the reef was the open Indian Ocean – this island was on the outside of the atoll, and on the eastern fringe of the ridge on which the Maldives sits.  Weather often approaches from the east and this is where storm surges and wind can do the most damage.  The water was choppy here and the land had been steadily chomped away by the wave action.  The roots of palm trees were exposed and in some cases had been completely undermined and the trees toppled into the water.  There was hardly any sand here, lots of pebbles and loose bits of bricks and rubble and coral.

Only about 50m from us was the reef edge – a slim line of coral that was just about above the level of the current waves.  They smashed against this wall, constantly chipping off bits.  It would be a miracle if the coral were able to regenerate at the same rate as it was being eroded.  About twenty years beforehand money was spent on building up the coral reef with concrete, but no maintenance had been done since, and much of the rubble we could see on the beach was what had been pounded out from this old defence.  The rest came from recycled building material that the villages had used to fill in the gaps in the natural coastline – stopping up breaches, replacing the net of roots that had been lost.  This exposed coastline was not far from the sheltered northern harbour which we had arrived at, and this end of the island was almost completely covered in housing plots – all built on.  The coastline was gradually retreating and in some places had dislodged the blocks making up perimeter walls.  In a couple of places houses had been abandoned where the land had been eaten away too close to their foundations.