Experts find mangroves can slow surge

| 21/08/2012

front.jpg(CNS): Evidence from the latest scientific research suggests that mangroves can reduce the height of wind and swell waves over relatively short distance. According to a report by the Nature Conservancy and Wetlands International wave height can be reduced by as much as 66% over 100 metres of mangroves. With coastal populations particularly vulnerable to the impacts of extreme events such as storms and hurricanes researchers say mangrove forests can be used as a tool in coastal defence strategies making their conservation a key part of protection. Researchers say that more work needs to be done to better understand the role they can play in defending coasts.

While Cayman does provide for some protection of mangrove buffers under the planning regulations, the plant is still persistently removed in the face of development. This was evidence in 2010 when more than 370,000 sq.ft of costal mangrove was ripped up by the developer of the Ritz Carlton on land earmarked for the Dragon Bay development.
Michael Ryan was granted permission to rip out the mangrove more than two years ago but no development has taken place on the site. In addition the promised replenishment programme has also failed to materialize.

In this new report by the environmental researchers, the importance of dense healthy mangrove to protecting coastal areas from storms has been highlighted as the experts say the plant reduces the wave energy.

“While mangrove forests are usually found on shores with little incoming wave energy, they may receive larger waves during storms, hurricanes and periods of high winds. Large wind and swell waves can cause flooding and damage to coastal infrastructure. By reducing wave energy and height, mangroves can potentially reduce associated damage,” the authors of the new report state. 

“All evidence suggests that mangroves can reduce the height of wind and swell waves over relatively short distances: wave height can be reduced by between 13 and 66% over 100 m of mangroves. The highest rate of wave height reduction per unit distance occurs near the mangrove edge, as waves begin their passage through the mangroves," the report finds.

It explains that waves are most rapidly reduced when they pass through a greater density of obstacles.

“Mangroves with aerial roots will attenuate waves in shallow water more rapidly than those without,” the researchers say. “At greater water depths, waves may pass above aerial roots, but the lower branches can perform a similar function.  The slope of the shore and the height of the waves also affect wave reduction rates through mangroves.”

With confirmation that mangroves can attenuate wind and swell waves, the report states that research has focused on small but there is a need to measure the attenuation of larger wind and swell waves associated with greater water depths, which may occur during hurricanes.

“While more research is needed, existing knowledge is sufficient to substantiate the claim that mangroves attenuate wind and swell waves,” the report concludes. “Appropriate management of mangrove areas could increase wave attenuation. This might include the protection of mangrove areas in key settings, or lead to the restoration or planting of mangroves in degraded and deforested settings, where local conditions have been shown to support the establishment of mangrove seedlings.”

The authors go on to say that dense mangrove forest, including species with aerial roots will offer the highest level of protection from wind and swell waves.

See report here

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Category: Science and Nature

Comments (22)

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  1. Anonymous says:

    There are surely a lot of armchair experts in Cayman.

    What ever happened to common sense?

  2. Anonymous says:

    Are they so blind they cannot see? Before they was any development ,did it not flood? My Aunt in Bodden Town had alzeimers and all she spoke about was 32 ' storm . The other bad hurricane when we didn't touch any swamp. We had the same damage , she said you could see all of Breakers from Lorna's gas station in Bodden Town. My father lived in Pedro one mile from the sea . He and his cousin went to Pedro st james and watching the seas crashing on the shore .The sea went from there all the way to the north sound the only difference was the water was deeper. My father lost his dog in the 'river' that formed going through to the north sound. 

    Hurricane michelle that caused damage to Turtle farm ,Tortuga rum and Cracked conch had no swamp and yet the sea did not cross the street. Yet people were on the road picking up rum bottles and turtles. That hurricane was in Pinar del rio, Cuba. How was swamp going to stop any of these floods? Didn't you all see floods in george town? So are you all saying no air port? They had 9 feet of water come from south sound across the barrier reef straight through windsor park across the airport ending in the north sound. 

    Is it not true and think for a minute that noone would have had roof or building damage if  it had hurricane straps and concrete construction? As far as flooding they were people who built their houses higher then their neighbors and had no flooding. When Mariner's Cove was pushed on to the streets and blocked east to west travel , did you not see Rex Rankine concrete house still standing? They were next to each other , what did swamp development have to do with any damage they incurred? Nothing. In fact if you bought cheaper land in the swamp then you should have built it higher. Thats all you can do. 

     

     

  3. Anonymous says:

    I think this is now COMMON SENSE!

  4. Young Caymanian says:

    OH REALLLLLLYYYYYYYYYYYY NOWWWW. HMMMMM I WONDURRRR. After all those years, after all those buildings, after all those canals, after all those hotels. Now it's been scientifically proven. O well, we cant expect any better. Remember we're not smart enough to prove anything on this Island.

  5. Anonymous says:

    How much did they spend to figure out that waves slow down if you put something in their way?

  6. Developer says:

    But this research does not deal with the impact making sensible environmental choices could have on the secret bank accounts of politicians involved with planning and duty waiver processes.

  7. Animaliberator says:

    In addition to the others comments: And they just figured this out? Gosh, some people really need a slideshow don't they. Now you see it, now you don't with all the consequences attached to it. Mangroves are also an eco system all by itself and all the natural benefits that come with that. I suppose that is also mentioned in that conservation law that we will likely never see come to fruition. With this incredible desire to see and feel more water then we already have, water is all you will have soon enough. Haven't we not learned already that water is 10x or more destructive than wind will ever be? Ivan should have taught us a little lesson but I guess not the way we keep destryoying what little mangrove is left right now in certain areas. I am glad however that certain people continue to emphasize the fact that mangrove must be preserved no matter what comes around.

  8. the truth says:

    Its simple people! the Minister in charge of "environment" has been there for 3 long years and cant manage to bring about the "Conservation Bill". The Developers are just taking advantage of the "taking candy from a baby situation" that our politicians have provided them with. However, the immagration laws and planning laws, police laws, have been changed serveral times along with several others. Politicians have a shady ora the world over but in my country of Cayman they have no one to answer to as they have put on high their friends and supporters in roles of whcih the utmost impartiality is required to properply provide just actions to the inhabitants of this island. XXXXX When the generations before mine (i'm 26 by the way) Caymanians were docile and passive and turned a blind eye to the storm brewing just off their shores, now that it has reached, everyone seems to be in such disarray that they're being told, "we are moving your Roads", " You have to vacate Safe Haven", "you Expats we're going to tax" . Let the little man get some concessions on Duties when trying to build a house, or run a business? NOOOOO! Let Multi million dollar Developers and Business men get 10's of millions of dollars in Duty concession? YESSSS! That is the Logic behind those in power.

     

    A wise man once said, "IF YOU FAMILIARIZE YOURSELF WITH THE CHAINS OF BONDAGE, YOU PREPARE YOUR OWN LIMBS TO WEAR THEM! "

                                                                                                                       

    The Truth

     

  9. Anonymous says:

    DUH…….truth and experitse mean nothing to the greedy powers that be or the greedy developers so the intelligent ones of us and those with some common sense that know the facts are forever hacing to fight fight fight to save Cayman.  This is why we are always petitioning, petitioning, petitioning to try to save some of what we KNOW needs to be saved…..Please feel free to join our movement…..we know how important some things are around here……like leaving the West Bay Road where it is……Do you see how much more mangrove environment has already been destroyed again by one such greedy developer?????   XXXX

    • Anonymous says:

      OMG How long have we been saying this…..and does anyone remember when the Ritz tore town the mangroves on west bay road and placed huge mounds of marl in front of it so no one would notice…..look at the destruction that hotel has done, and Ryan has no control over it either…give him status, why not?? Cause someone made money off of it…..Mangroves torn down, oh yeah I forgot, got approval to build a taller hotel, taller then the tallest coconut tree, why? cause someone's pockets got lined….300 and some odd work permits being held by the Ritz….what happened to all the jobs they were going to give Caymanians…sorry I know this is a bit off of the mangrove discussion but it all goes back to WE SOLD OUR ISLAND OUT!!!

  10. Young WBer says:

    OOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMMMGGGGGGGGGGoodness

    its almost like what every old caymanian has been saying since people started tearing down mangroves to make way for pretty beach front property to sell were not just talking to talk they where actually telling the truth!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    P.O.

  11. Anonymous says:

    This is well documented in recent history and a lesson that needs to be heeded.

    I remember Bimini in the Bahamas, August 23 1992, when Hurricane Andrew came straight through the islands but the storm surge was broken up by mangroves and a large, shallow lagoon. There was wind damage (it took the whole roof off my hotel) but nothing like the destruction that would have occurred if the place had been hit by large waves. Bimini was back in business within 2-3 weeks.

    Old saying 'Nature takes care of itself'. You start destroying natural growth and you will suffer the consequences. You should have left the mangroves alone Mr Ryan.

  12. Anonymous says:

    We old timers always knew this.

  13. Anonymous says:

    We knew that!

    It is a pity that developers like Dart and politicians like McKeeva Bush did not know this, too greedy, they will never learn.

    Nature Conservancy and Wetlands International please do not waste your time sending a copy of this report to the Cayman Islands becaue the truth will be ignored.  Find a country that has not sold out the people's minds.

    Caymanians are too weak and corrupt to put a stop to the damage of anything naturally beneficial to us. 

    Sad but true.

     

     

  14. Anonymous says:

    Well that sounds great buuuut with 66% of our swamp untouched we still got 8 ft of flood water .  One of our realities is that everyone lives on the coastline from rumpoint to east end bodden town to georgetown to west bay . So how is the amount of dont cut down mangrove going to save us from surge? We have been arguing this baloney for thirty years. The reality of another huricane like Ivan or worst a direct hit will not deter the unavoidable  flood . So why don't we start  solving this problem . Change planning law to say all buildings built close to the coast to be built 10 feet higher then the road plus drainage. The places on this island that flooded during 1932 hurricane ,were the same places that flooded in 2004. South sound new construction got it right  , grand harbour did very well during hurricane ivan . Yet across the street on the sea side had 8 fteet.  Ocean club has no mangrove but next door the Thompson's  new apts should be no problem but the surge past Rex creighton house across the street  heading north straight through prospect properties omega bay estates. No way is this discovery going to help this little island so please start filling your propeties like you see across the street from Caribbean Club or build using stilts . This is the right way for the future of Cayman.

    • Anonymous says:

      Anon 1140 the flood is one thing but the large battering waves are another thing.

      Look at how bad properties were damaged that were exposed such as Mariners Cove and Ocean Club. Look along the south coast after the passage and see how bad the homes were damaged. You want 10 feet more fine but I say those homes would still have been damaged even with that amount.

      You also need to understand that Ivan was a minimum cat 5 at best. What would have happened had Mitch come through? Thing twice as much storm surge at least and longer period of battering waves and strong winds.

      Sorry I will take my chances with the mangroves. You can have yours with your money.

      • Anonymous says:

        I think mangroves are swell but they will not help you in a big hurricane. If you're only 5 feet above sea level kiss your house goodbye.

    • Anonymous says:

      I wish there was a pill for stupidity but unfortunately there is none. 

    • Anonymous says:

      You sound like one of the advisors from the Mariott Beach Resort they too had the bright idea about the high water mark and the mangroves being worthless.  They tore it down and if memory serves me right prior to hurricane Ivan they tried to remedy the problem without success.  I believe even plastic grass was used at some point.  It had to take mother nature to rectify the minstake done by mankind because of greed.  Save for the few God fearing people that are left on these islands I really wish that God would again show people like you that he cannot be bought or sold and the reasons for the mangroves. 

  15. Anonymous says:

    And with all this knowledge of all the benefits that mangroves provide to this island, they'll be torn down for a quick dollor. As a Caymanian I'm ashamed to see where this island is headed. The leaders of this country have no consern for the natural wellfear of this island! Any foreigner can come hear, throw a few dollors and take over and do as they please!

    My children will never know what it's like to take a sunday drive on west bay road and see the ocean…and why because all our leader has in his eyes are dollor signs! It's a real shame.

  16. ah boy says:

    God knows why he creates things, everything has a purpose. Why we have chosen to remove these plants from our coastline instead of incorporating them into the landscape plans is beyond me. All for the love of $$$