1/ More Sand Sausages.
2/ An artificial reef or bank.
3/ Continual re-supply of sand from the Otago Harbour/Tomahawk
4/ Sand trap fences, as Duke Gilles did in the old days
5/ Relocating Mitre10 Mega as an artificial reef
And all agreed the current action, although necessary is not a solution at all, just a bandaid.
I have had contact with an overseas company (Holmberg Technoligies) who have extensive experience and sucess in coastal dune restoration, and thought it offered an alternative to what is currently proposed, all it would need is the suppoort of the powers that be financially to empower the work.
Below is a copy of an email I received back from them:
Hello Nic,
Thank you for contacting Holmberg Technologies Inc.
Your contact details have been forwarded to me as the Rep.
"down under."
I've checked your Blog out and it is great! - you and fellow
Bloggers appear to share our concerns re conservation of the
coastline.
The situation on the coastline in Otago reminds me of the old
Chinese proverb which goes something like: -
"A crisis is merely an opportunity in disguise!"
The crisis on the Otago coastline is an opportunity for our
company to assist you through our knowledge and experience
and, (I suggest) an opportunity for stakeholders to learn
from the past, and open their minds to support a proven
alternative.
>From your perspective at least stakeholders should have
learnt some tough lessons about the limitations of concrete
walls and sand filled tubes and (soon to come!) sand
replensihment as a means to "defend" the land against the
open sea!!!
These methods simply dont work effectively (without adverse
effects on the environment) because the basic underlying
strategy of trying to defend against the sea is
fundamentally flawed.
Holmberg Technologies Inc's strategy is to facilitate
reconstruction of a beach profile to create a natural self
sustaining beach and dune system - i.e. Holmberg's strategy
works with nature rather than the "traditional" engineering
approach of working against nature - like most brilliant
ideas quite simple really!
To do this we use geotextile tubes filled with concrete to
initially (and after storms) trap sand suspended in the
system to rebuild the beach profile.
We use concrete because experience has shown that sand
filled tubes dont stay intact for long, replenished sand
washes away (and eventually money runs out for its
replacement etc.) and the new beach needs the solid
underpinning of concrete to cope with storm conditions.
The tubes we use become buried out of sight very quickly in
open coastal environments and have not been shown to
interfere with the surf zone.
As you will have probably seen from the examples on the our
website Holmberg Technologies Inc has the experience and
technology to manage the type and magnitude of situation
which you are facing in Otago.
What we will need eventually however is the united support
of stakeholders.
If you have questions please do not hesitate to contact me.
I have attached some introductory information which you may
want to post on your Blogg.
Kind regards,
Chris Johnson,
Australasian Representative
For Holmberg Technologies Inc.
_____________________________________
Some more information about Holmberg Technologies
_____________________________________
Holmberg Technologies Inc.
Undercurrent Stabilizer™ System
A Proven Alternative Coastal Erosion Management Solution
Globally, the issue of how to effectively manage coastal erosion is of increasing concern to those who have an interest in the conservation of our precious coastal environment.
Over thirty years ago, Dick Holmberg, a visionary environmentalist, with a unique understanding of the oceans’ behavior gained from his experience as a deep-sea diver, became concerned about coastal erosion and the shortcomings of the methods that were being used to manage the problem. He responded by pioneering the development of an alternative coastal erosion management solution – the Undercurrent Stabilizer™ system.
To-date, Dick Holmberg’s company - Holmberg Technologies, Inc.- has applied Undercurrent Stabilizer™ systems to successfully manage coastal erosion in over 100 projects, responding to a wide range of site characteristics and objectives for clients that have included government, community and private interests.
In contrast to traditional approaches to erosion management, such as rock walls, groynes, artificial reefs and sand replenishment, Holmberg Technologies’ Undercurrent Stabilizer™ systems derive their success from working with nature, rather than against nature, to facilitate the reconstruction of a permanently self-sustaining shoreline environment.
A significant benefit of the Undercurrent Stabilizer™ system is that because it is a permanent self-sustaining solution, installations typically involve a once-only cost for assessment, design and construction. In most cases ongoing maintenance costs normally associated with traditional solutions are eliminated. At around US$2 million per mile Undercurrent Stabilizer™ systems are significantly cost-effective when compared to traditional solutions.
Often described as seabed speed bumps, Undercurrent Stabilizer™ systems are designed to slow sediment (e.g. sand or gravel) laden currents, to halt erosion and induce accretion.
Undercurrent Stabilizer™ systems successfully reduce wave energy and current velocities forcing the precipitation of indigenous sediment onto the shore. This reduction in velocity and hydraulic energy also reduces transport of sediment from the shore. The technology restores and protects the near-shore as well as facilitating the restoration and conservation of dunes and bluffs without interfering with the outer surf zone. The technology remains in place providing solid underpinning which facilitates storm protection.
Provided an initial feasibility study proves to be positive, an Undercurrent Stabilizer™ system is custom designed to address site-specific conditions, characteristics and performance objectives.
The system typically includes a geo-mass template designed to re-contour a deficit near-shore profile (one that loses sand) into a shallow, gently sloping accretion profile (one that gains sand). Each system is an interlocked network of concrete filled geo-textile tubes that extend like long “fingers” perpendicular to the coastline and sometimes incorporates a shore parallel component (especially where bluff or dune undercutting by wave action is possible).
Once installed, the technology follows the slope of the beach and near-shore and disappears completely out of sight, as the beach-face and near-shore accretes.
The effectiveness of Holmberg Technologies’ approach to coastal erosion management has been verified by independent scientific and technical studies and supported by international university research, as well as by thirty years of empirical evidence.
For more information visit: www.erosion.com and www.blufferosion.com
In Australia or New Zealand contact:
Chris Johnson, BBS. Australasian Representative, T/F 00-64(9)-5358066 – Email: andresim@ihug.co.nz
0 Response to "An alternative Dune Solution"
Posting Komentar