Showing posts with label atoll. Show all posts
Showing posts with label atoll. Show all posts

Wednesday, May 20, 2009

Thoughts - Atolls, Beautiful Daughters of the Reef

The following is an article written by Alex du Prel, publisher of Tahiti-Pacifique magazine. He offers it for your reading pleasure. Enjoy!


Atoll Beach

A beach landing area on an islet on Bora Bora's fringing reef (AKK_1731.jpg)

"I love reefs because that's what creates atolls.

I am a nut about atolls. I live them with passion. "Stupid you," say some friends, "How can you be crazy about a pile of sand?"

Well, maybe. But an atoll is a different universe. It's fragile jewel. A new world altogether. A place of intimate communion with nature. For it's the only land on earth created by life. By a living organism, coral. And it's a clean living sphere, so rare today, where you can even walk barefoot all day without ever having muddy, dirty feet.

An atoll is not the result of the clashing of tectonic plates nor a piling up of some rocks. It doesn't erode, it grows. An atoll is the offspring of a secret pact between the noble elements of our planet. The fire of the bowels of Earth places the embryo; patience of time shapes it; water and sun nourishes it; the wind weans it.

Look at the Pacific Ocean. Huge. Vast, never ending. So vast. More than half our planet. Deep also, more than four kilometers deep, on average.

A small weak spot in the cold dark bottom of this endless blue water ocean. And the fire of genesis will slowly, patiently, step by step, push the magma up until, sometimes, it will breaks through the surface of the sea. This volcano then, a huge mass, from it's base to the sea level will be taller than the highest mountain on some continents.

The volcano will eventually run out of fire, will become extinct. Its weight, so massive and so lonely thousands of kilometers from any continent, will make it sink. Slowly. Inevitably. Erosion from rain and wind will help it disappear again below the sea.

But a small detail changes everything. Tropical polyps, the coral, will discover a perfect habitat on the slopes of that sinking mountain.

A solid base. A warm ocean. Lots of light, sunshine. And tons of oxygen provided by the endless surf produced by steady trade winds or storms in the far Roaring Forties.

As the volcano keeps sinking, the coral will keep growing. Generation after generation on top of the calcium skeletons of their ancestors. Soon all trace of the volcano disappear - just a ring of coral will continue to grow and a lagoon will be born. An oasis of teeming life in warm tropical waters known to lack nutrients

The never stopping swells of the huge ocean will then cuddle this fragile jewel with loving care. Stroke it with its waves. Feed it with its oxygen. For centuries, ages, eons.
But nature, just like man, can turn momentarily insane, crazy, violent. Especially when it feels too hot. In its short folly it will try to destroy, maim, mutilate what it had nurtured with much patience, softness. This insane fit is called a hurricane, typhoon, cyclone, whatever.

Monstrous waves, like tremendous sledges, will then pound, break, smash the fragile and colorful underwater gardens. The nursing swell turned into a destructive ram will lift entire reef sections up, throw them on top of others; will grind coral and beautiful shells into sand.
Worn out, the ocean will quiet and expose a view of desolation in proportion to its short fury. On the wounded reef large mounts of debris will rot and stink in the reappearing sun.

A few years later, the rains will have rinsed the salt out of these new dunes. Sea birds will joyfully discover a new roosting place. Their droppings will provide nitrogen and seeds. A few years later the dunes will be green with bush, grass and other vegetation. Some coconuts will be washed on these new shores and will find a place adequate to take root.

An atoll just has been born. An island consisting only of a sandy ring, one of these "islands full of water" with no trace of mineral soil. An island whose future entirely depends on the continuous growth of the reef. A reef which will repeatedly heal itself, continue to be the protective barrier for the fragile sand island and provide a never ending supply of new material. Without the ramparts made of billions of living polyps, the swell would just take one swallow of these storm leftovers.

There is all the ambiguity of an atoll : every time the weather has a fit, churns the ocean and tries to destroy it, this action only creates more debris that adds material to the atoll, providing more land. That's why an atoll, pure product of the reefs, is a living being that feeds on its environment, adapting to and thriving from its moods.
Lots of time will pass. Lots. Eternity. The fringing islands (motu) on the circular reef will get large enough to permit a fresh water lens to establish itself, which in turn will allow the growth of taller trees, like the coconut tree or the pandanus tree (screwpine).

Then, some day, some men, lost on the endless sea, crowded in a fragile outrigger canoe, will be washed onto these remote shores.
They will worship this life saving land. They will learn to survive, even prosper on these few and ever lonely acres. Learn to peacefully cohabit on it. They will figure out how to feed themselves, how to dress, how to heal with only coconut, fish, shells, taro and live that way for generations.

Actually, unless you are an absolutely stupid urban dude, you cannot die of hunger on an atoll. Beside the plentiful fish and shells that thrive in the lagoon, the lobsters on the reef (on moonless nights), there are coconuts and land crabs on the motus next to many other plants that can be eaten as salad or as a snack. Not to mention the many birds, and their eggs. To obtain fresh water other than the one in coconuts, one takes a big shell and digs a hole in the sand in the center of a motu, a meter or so deep to find the fresh water lens.

This reminds a story. I had the luck to be the manager of a small atoll (5 km diameter) with just a tiny hotel on it, De Luxe Robinson Crusoe style, with no other population.

One day, after a long walk along the beaches, we discovered on the other side of the atoll a sailing yacht laying wrecked on the barrier reef. On the beach opposite the wreck, a terrified family with two teenage children was camping. They were in rather poor shape, emotionally as well as physically. They had crashed onto the reef one night 10 days earlier and, poor navigators (that's before GPS existed), they thought being stranded on an uninhabited island. They had stayed close to the wreck of their yacht because that's where their (canned) food, and their water were. But one must admit they did manage to open and eat a few coconuts. Would they have been just a little more adventurous and only have crossed the motu to it's lagoon side (about 200 meters), they would then have been able to see in the evening, across the lagoon, the lights of the restaurant where one could order quite a fine meal, fit for Western taste with even a good wine, if you please.

An atoll is also a place where cultural shock do happen. Like this gentleman from New York. Instantly transported with no preparation from Broadway to primitive nature thanks to the speed of jet airplanes, he suddenly discovers in front of him the splendor of the lagoon and it's thousands of shades of blues and greens. Stunned, he walks (in his city shoes) to it's edge, cups up a handful of water, looks at it while it runs through it's fingers, tastes it and walks up to me;
-" Excuse me, Sir, may I ask a question ?
- Pllease do.
- Could you tell me what you put in the lagoon water to keep it so clear ?"
True, authentic, no joke!

Another time, a very blasé wealthy gentleman and his young secretary-mistress spent the week-end on the atoll. I take them by boat to one of the bird islands. Standing on an immaculate and long white sand bank, before a background of thousands of coconut trees beyond the shades of blue, with hundreds of birds flying around us while other stand lined up on the beach looking at us, I realize the gentleman is impressed. This makes me proudŠ until he says : "How much an acre ?" The secretary-mistress hit him on the head with her "Night of the Iguana" style umbrella.

Or this young very nice Italian of good breed who arrives for honeymoon with his fresh wife, a socially "active" girl. While the groom immediately fell under the spell of the atoll and it's peace, the lady realizes no one is there to be jealous of her wardrobe or to be impressed by her importance. Thus, all week long she complains about everything, continuously nagging her husband, typical syndrome of people who cannot bear to be alone with themselves (that's why bars have much business). When the couple leaves, the Italian lets his wife get aboard the small plane and tells me :
- "I'd like to apologize for her behavior." He adds , smiling : "Also, I'll be back soon, with another wife !"
I answer : "Great, but make sure you bring her here BEFORE marrying her !"

Permanently living on an atoll is a dream for a person who has the right mentality. But it also has it's risks. Just go to the "highest" spot on one of these atolls in the Pacific Ocean and stand there to admire the thousands of shades of blue waters in the lagoon. After being dazzled by such beauty, you might also look at your feet. It's then that you realize that this highest spot of the island is just a little pile of gray coral chunks, only 3 meters above sea level, next to the pass, facing the breakers of an endless swell curling along the barrier reef.
Now look to your right. Only ocean : 9000 kilometers of open ocean to the shores of South America. Look to your left : 7 000 kilometers of rolling swell to the beaches of Australia. Look behind you. 6 000 kilometers of stormy ocean till the icebergs of Antarctica. Look in front of you: another 9 000 uninterrupted kilometers to the Bering Straights, icy shores of Alaska and Siberia. You've just learned what isolation, real isolation, means.

Now think of these chunks of coral under your feet. You suddenly shudder. You just realized that it's the ocean that put the coral there. And that it can take it away just as easily. Three meters high in an ocean that spans half the planet is less than the tenth of the thickness of a cigarette paper floating in an Olympic swimming pool. Yep ! Andthe island is NOT floating.

A major cyclone. A tsunami created by some big earthquake in Chile, in Alaska or Japan. A major underwater volcanic eruption. A big meteorite falling into the sea. Any of these events can generate a wave that would just roll over this pile of broken coral, without even noticing, flushing into the open sea everything, sand, trees, shells and people. Everything. It has happened many times, and will happen again in one hour or in ten thousand years. Who dares say that guys like me who escape to these sand islands are cowards running from the reality of life ? This must be one of the most dangerous spots on earth. Living here is like playing continuous Russian roulette. But isn't risk the spice of life ?

Sometimes it can even get funny, unbelievable. Like getting flooded by fresh water, yes, fresh water, on an island surrounded by ocean, without a lake, a river, not even a tiny creek : It happens about every 20 years in the Tuamotu archipelago : a huge swell created by some major storm in the North Pacific arrived in the Northern Tuamotus, 8000 kilometers to the South, and raises the sea level to such a point that the freshwater lenses of the atolls get flushed up, out of the ground and inundates villages of many atolls.

But whatever, I'd rather be on an atoll.

©2009 Alex W. du PREL

Moorea, Tahiti
tahitipm@gmail.com

Published (in German translation) in "Mare Magazin", April 2009.

Tuesday, March 24, 2009

Manihi Atoll FP - First Landfall in the Tuamotus


Manihi Atoll Locator Map


Manihi Atoll - Landsat ETM+ Image S-06-10_2000 (1-110,000)

Manihi Atoll - Landsat ETM+ Image S-06-10_2000 (1:110,000)


Manihi Atoll - EVS Precision Map (1-110,000)

Manihi Atoll - EVS Precision Map (1-110,000)

Manihi Atoll is one of French Polynesia's premier destinations for the tourist wishing to view pearl farming first hand. According to the Tahiti Tourism North America, Manihi Atoll has over 60 working pearl farms. While one is looking for those perfect pearls, the Manihi Pearl Beach Lodge beckons. This atoll is one of the first landfalls for the visiting yatchsmen traveling from the Marquesas to Tahiti.


Manihi map-big (500)

Manihi Atoll - Pacific-Image Map

In doing research for Manihi Atoll I came across the Pacific-Image map. As to names of the various motus, it is complete. As to cartographic quality, it looks like a map, it seems like a map, and it is a map, one designed for the tourist. If you are into high quality tourist maps of Pacific Islands, specifically the islands of French Polynesia, for only $237.60 you can purchase a CD loaded with 72 of these very attractive maps.


Detail Manihi Map Image-Pacific

Manihi Atoll - Detail from Image Pacific Map


Manihi Atoll - EVS Precision Map - Detail Tairapa Pass and Paeua (1-30,000)

Manihi Atoll - EVS Precision Map - Detail Tairapa Pass and Paeua (1:30,000)

Although the Tahiti Pacific-Image maps are excellent for their purpose, I like mine better. Compared to the Tahiti Pacific-Image map, my EVS precision map of Manihi Atoll takes into account a wider variety of layers of information. In addition, my maps are vectors, whereas Tahiti Pacific-Image's maps are raster images.

As to the production of this map, it was not particularly difficult to digitize and ultimately create the island map. However, my very busy life caught up with me and what should have been a 10-hour project, took two weeks to complete. I have other island projects in the works, but they will be completed and posted at this much slower pace. Until then...

Enjoy!

Friday, October 31, 2008

How To Digitize EPIP's Four Atoll Layers

What is EPIP?

Enhanced Vector Precision Island Polygons - Using Landsat ETM+ ortorectified image mosaics as my base images, I digitize various layers of information, most typically from islands. I use Landsat ETM+ because: 1) It is free. 2) It is typically cloud-free. 3) It is consistent in quality. 4) It covers the earth. 5) It is virtually copyright free. This is the degree of precision over 8,000 South Pacific island polygons have been digitized to. This level of digitizing precision over such a broad expanse (South Pacific) is quite an accomplishment. What does this level of digitizing precision entail? What are the layers of information being captured?


Atoll Digitizing - First Layer Vegetation (Hi-Lo) Layer

Atoll Digitizing - First Layer Vegetation (Hi-Lo)

The first layer I digitize is vegetation. Working at a scale of between 1:25,000 to 1:15,000, I carefully digitize layer outlines. Working with the vegetation layer, I have been known to make a number of vegetation classifications. For the purposes of EPIP, I make one classification - Vegetation (Hi-Lo). This broad classification focuses primarily on land vegetation. I am reasonably certain I digitize some patches of reef vegetation as well.


Atoll Digitizing - Second Layer Island Polygon

Atoll Digitizing - Second Layer Island Polygon

My second layer of information is the island polygon. As the name implies, this should be any above-water land feature. When digitizing an atoll made up of many small motus located on a complex reef that is often awash the difference between above-water, reef awash and below-water can get fuzzy. It is within this layer that I am certain I include reef features that are either awash or just below water. In this layer, I prefer to digitize too much as opposed to too little. Perhaps the next generation of Landsat imagery will allow for a clearer land vs reef determination. Until then, I'll digitize in as consistent a manner as possible.


Atoll Digitizing - Third Layer Reef Shallow

Atoll Digitizing - Third Layer Reef Shallow

This is another layer that I have used a number of classification. For the purposes of EPIP, whatever is visible (shade of blue) that I have not classified as a island polygon, makes up my Reef Shallow layer. This layer on the outer reef edge is typically defined by waves and/or a faint blue area along the shore. The inner reef shore also contains this blue area in varying shades and thicknesses. All of these blue areas are classified as Reef Shallow for the puposes of EPIP.


Atoll Digitizing - Fourth Layer Reef Deep

Atoll Digitizing - Fourth Layer Reef Deep

The final layer is Reef Deep or the central lagoon. It is basically everything within the atoll that isn't an island polygon or reef shallow. A crude classification, but it works well for EPIP.

I do all of my digitizing using Global Mapper. It is: 1) dependable 2) fairly inexpensive 3) simple to use 4) produces consistent product and 5) is serviced by Mike, absolutely the best customer service/owner of a product.


Atoll Digitizing - Four Layers - Vegetation, Island Polygon, Reef Shallow & Reef Deep

Atoll Digitizing - EPIP's Four Atoll Layers

And there you have it, EPIP's four atoll layers in all their glory. I'll share a few of my recently completed atolls with you. North is up and I realize they are unfinished maps without lat/lon, titles, north arrow and such, but they make the point, EPIP is a quality product.


Tahanea Atoll - EPIP (1:200,000)

Tahanea Atoll - EPIP (1:200,000)


Motutunga Atoll - EPIP (1:100,000)

Motutunga Atoll - EPIP (1:100,000)


Tunake Atoll - EPIP (1:50,000)

Tunake Atoll - EPIP (1:50,000)


Tepoto Atoll - EPIP (1:25,000)

Tepoto Atoll - EPIP (1:25,000)

Enjoy!

Tuesday, October 14, 2008

Comparison - LINZ 1:25,000 Map to EVS Map


I have been told by more photogrammetrist and cartographic professionals that Landsat ETM+ imagery is only reliable, for map production, between 1:125,000 and 1:62,500. Anything larger would not be cartographically sound. Good soul that I am, I believe them.

I understand that this imagery has pixel resolution reputed to be 14.5-meters at best. The way it has been explained is that each pixel resolves 14.5-meters of the earth, rendering Landsat ETM+ imagery as a satisfactory base from which to create maps at scales between 1:125,000 to 1:62,500.

It seems that Land Information New Zealand (LINZ) did not get the memo. Their Palmerston Atoll map, which I use throuhout this comparson, shows the same shoreline twists and turns my EVS Landsat ETM+ derived map does. They claim their map scale is 1:25,000 and without hesitation offer it to the world.

Close comparison of my EVS precision map and the LINZ Palmerston Atoll map are strikingly similar. Our shorelines are nearly identical. Our depiction of vegetation and reef layers are near mirror images.

I asked a representative of the LINZ cartographic group if Landsat ETM+ imagery was used in the production of their Palmerston Atoll map. He promised to get back to me with an answer. He never did. I suspect that LINZ cartographers used Landsat ETM+ imagery as an important foundational layer in the production of their Palmerston Atoll map. I, on the other hand, used Landsat ETM+ as my ONLY foundational layer.

So, all of you photogrammetrist and cartographers that are convinced Landsat ETM+ should only be used to produce maps at scales of 1:62,500 and smaller should explain to the LINZ cartographers that their 1:25,000 scale maps are not sound or, perhaps, give more credibility to Landsat ETM+ imagery. It seems that Landsat ETM+ base imagery can be made to work at 1:25,000 and EVS precison mapped shorelines are damn good!

Enjoy!

Thursday, August 14, 2008

Thoughts - My Progress at Mapping the Tuamotus

Tuamotus Progress

Tuamotu EVS Precision Mapping Progress

It has been nine days since my last post. What have I been doing? Keeping up with my summer duties - "honey do's", watching and entertaining my grandchildren (9 and 6 years) and mapping the Tuamotus. My goal this summer was to complete all 4 layers of EVS precision mapping for each of the 76 islands within the group - island polygon, vegetation, shallow reef and deep lagoon. To date 59 islands are complete. What exactly does that mean?

76 islands is not quite accurate. The Tuamotus are made up primarily of atolls. Each atoll has a number of islands, motus, to be exact. Just how many? A preliminary count puts the number of motus at approximately 5,640. Those are above water land. If the motu contains vegetation, I create a vegetation polygon. That means another 1,100 polygons to create (about 20% of the motus contain significant vegetation). Each atoll is surround by a shallow reef and an interior deep lagoon. However many of these interior lagoons are peppered with coral heads. If they show up on my base imagery, I map them. Probably another 2,000 polygons. All in all, I have to digitize 8,740 polygons, at least, to complete my summer project.

I have finished 59 atolls leaving me only 17 atolls to map. That is the good news. Now for the challenging news. Those 17 atolls will contain about 60% of the remaining polygons. All I have left to do is digitize another 5,240 polygons and I'll be finished.

If that seems like alot, it is. However, when this island group is mapped to EVS precision I will have accomplished my summer goal. It might be December 2008 before I complete my summer goal, but complete it I will. Wish me luck and...

Enjoy!

Saturday, June 21, 2008

Reao Atoll FP - The Finished Map

Reao Atoll - ISS004-E-12987, 12988, 12989 Images (1-100,000)

Reao Atoll - ISS004-E-12987, 12988, 12989 Images (1:100,000)


Reao Atoll - Other Precision Map - Source ISS004 Images (1-100,000)

Reao Atoll - Other Precision Map - Source ISS004 Images (1:100,000)

This is my finished shoreline map of Reao Atoll FP. The imagery covering this atoll is of sufficient detail that other layers of information can be digitized, if I wish. For now I just want to complete shorelines within the Tuamotus at EVS precision or better.

Enjoy!

Friday, June 20, 2008

How To Map Motus


View Larger Map

Zoom In to See Pukaruha and Reao Atolls


Reao Atoll FP - ISS004-E-12987, 12988, 12989 Images Modified (1-75,000)

Reao Atoll FP - ISS004-E-12987, 12988, 12989 Images Modified (1:75,000)

For whatever reason Landsat ETM+ does not have a mosaic that covers Reao Atoll. Google Earth has Landsat imagery, but no imagery for this area at the NASA site where I download my Landsat ETM+'s. As I am making all of my maps without using DigitalGlobe imagery, because one day I might want to sell my shorelines, I must locate other imagery sources. The International Space Station (ISS) is a source of sometimes excellent imagery. And, in fact, ISS004 has 3 cloud-free, highly detailed images covering Reao Atoll, my current target project.

I downloaded, modified their sizes, constructed a "whole atoll" mosaic, rotated the image to align it with my base island shoreline vectors (NGA PGS vectors) and georectified this image using 7 GCPs.


Reao Atoll FP - Other Precision Mapping on ISS Images - Finished Motus (1-40,000)

Reao Atoll FP - Other Precision Mapping on ISS Images - Finished Motus (1:40,000)


Reao Atoll FP - Other Precision Mapping - Finished Motus (1-40,000)

Reao Atoll FP - Other Precision Mapping - Finished Motus (1:40,000)

Once I had a georectified image, my digitizing could proceed. I decided to map motus first, thus the title of this post. Motu mapping is quick, repetitive and gives one a sense of completion. Each motu is actually a small island. Reao Atoll will ultimately be made up of a 100 or more islands. The two above images show the results of about 2-hours worth of digitizing. I always strive for EVS precision, Landsat ETM+ resolution or better. This imagery allows me to exceed EVS precision. For mapping quality purposes, I label it as Other precision and label it's Source attribute as ISS-Hi Res. I have completed 58 Other precision island polygons. Let's look at the challenges one encounters as they map motus.


Reao Atoll FP - Other Precision -  Digitizing Motu (1-10,000)

Reao Atoll FP - Other Precision - Digitizing Motu (1:10,000)

First, I am working at 1:10,000 scale. At this scale, I am able to maintain sharp feature clarity. In addition, this resolution allows me to make consistent shoreline determinations that will work with the scale of my finished map, between 1:50,000 to 1:25,000. My mapped shorelines consist of actual or suspected (based on color) above-water features. Sounds easy enough to consistently identify, but it isn't. After mapping a few thousand motus, I have learned to make a color(s) to shoreline decision and rigourously adhere to that definition. In imagery, color is god.

In the Reao Atoll image, the motu shorelines are identified as a white sand color. Having studied enough hi-res 1-meter imagery of reefs and motus, I know that between motus are features called hoas. These serve as channels allowing water to flow in and out of the lagoon. Eventually, these hoas fill up with coral rubble and sand, vegetation takes root and motus join motus to form a continuous land ring around a lagoon. Given enough time, the lagoon quite often fills in and, sea level cooperating, a flat island forms where an atoll once stood. Using my white sand color as my motu shoreline, I began digitizing.


Reao Atoll FP - Other Precision Mapping - Finished Motu (1-10,000)

Reao Atoll FP - Other Precision Mapping - Finished Motu (1:10,000)

If I do a good job, my project consists of a series of motu shorelines. The digitizing is monotonous, eye-straining and lately, my feet hurt because my chair is uncomfortable. But the finished map is what I work for. I'll share it with you when I've finished. Until then...

Enjoy!

Sunday, February 3, 2008

Nukutavake Island FP - Third Time Posting is the Charm

Nukutavake Island - Image

Nukutavake Island - Landsat Image S-07-15_2000 (1:25,000)


Nukutavake Island - Map

Nukutavake Island - Marplot Map (1:25,000)


Nukutavake Atoll - EVS Precision Map (1-25,000)

Nukutavake Atoll - EVS Precision Map (1:25,000)

The second map is the new and improved version of my EVS Precision island maps. Not only have I made better use of the text fonts found in Marplot, but I've added a North Arrow. Also, and most important, I've adjusted the colors. I promise that any of you creating a large body of original maps will find yourselves constantly tweeking the colors. This particular color pallet is probably version 101. Seriously, colors are the ultimate subjective layer of information one places on a map. Quite often they reflect your moods. If you are having a bad day, wierd colors result and a good day leads to peaceful earth-tone pastels.


Nukutavake Island (Noukoutawake) is a small island, of coral formation, located about 8 miles NW of Pinaki. It is about 3 miles long in an E-W direction, and is wooded except at its E end. There is a radio station on the island.In May, June, and July the population of this atoll moves to Vairaatea, and in August, to Pinaki to harvest copra.

(SD Pub-126)


Group: Centre East Group
Archipelago
: Tuamotu Archipelago
Country: France - French Polynesia - Tuamotu Is.
Region
: Oceania 18
Lat: 19.28º S Long : 138.78º W
Area: 4.5 sq. km
Altitude: ? m
Depth to nearest land: 3000 m
Nearest island: 14.5 km @ 143° (Atoll Pinaki)
Group
: 980 km
Nearest continent: South America
Distance
: 5400 km Isolation Index: 108

ISLAND TYPE: low coral Natural Protection Indicator: 2
CLIMATE: tropical
CATASTROPHIC THREATS: cyclones Threat Indicator: 1
ECOSYSTEMS: Coconuts; fringing reef Number of Ecosystems - Terrestrial: 1 Marine: 1
Percent shoreline: Coral Reef: 99% Mangrove: 0%

HUMAN OCCUPATION: Uninhabited, ?
Population: 0 Density: 0.0 persons/sq. km
Major Human Activities: coconut plantations
Percent population in agr/mining/fishing: 17% Human Threat Indicator: 1
Gross Domestic Product: $ 7236 per capita Economic Pressure Indicator: 4

DATA RELIABILITY: Data Rel. Indicator: 1

HUMAN IMPACT INDEX HI: 5
CONSERVATION IMPORTANCE INDEX CI-Terrestrial: 5 Low
CI-Marine: 4 Low

Last updated: 27/02/89


Nukutavake (aka Queen Charlotte Island) is an atoll located in the eastern part of the Tuamotu Archipelago at 138°48’ west longitude by 19°17’ south latitude. It is 1,125 kilometers (699 miles) from Papeete. British Captain Samuel Wallis was the first European to discover this atoll in 1767. This is a unique atoll because although it is flat and of coral formation, it has no lagoon. While some accounts claim there are no signs of there ever having been a lagoon, other accounts claim that what was once a lagoon has been entirely filled in by sand and limestone particles from the external coral reef. Part of the atoll is covered by dense vegetation, while the rest has a coconut tree plantation covering some 800 hectares (1,977 acres). Nukutavake is 5.2 kilometers (3.2 miles) long. Its width ranges from 450 meters (1,476 ft.) to 1.3 kilometers (0.81 miles) in the director of the village. The atoll covers an area of 360 hectares (890 acres).

The village, located in the northeastern part of the atoll, has some streets and a main road from the coast and the coconut plantation. There is an aerodrome 800 meters (2,625 ft.) south of the village, linking the atoll to the outside world. There is a whaleboat dock opposite the village that allows for transferring people and cargo from and to cargo ships that anchor offshore. The 1996 census recorded a population of 196 persons. The atoll is the administrative center for a district made up of the associated districts of Vahitahi and Vairaatea.


This island was mapped quickly. Not carelessly, but quickly. It took about 1-hour to digitize and create the map. Another 30-minutes to post and comment.

Also, the discovery of the additional island information from the web site of the President of French Polynesia (what a job!) will enhance the information associated with this island. I did send him an email to present my website. However, no reply as yet.

Enjoy!

Friday, July 13, 2007

Nikumaroro Atoll KR - Exquisite Map or What I've Learned in a Year.

Niumaroro Atoll - Image (Landsat)

Nikumaroro Atoll - Landsat Image S-01-00_2000 (1:31,250)


Nikumaroro Atoll - Map

Nikumaroro Atoll - Marplot Map (1:31,250)

A year ago I thought this was a solid mapping effort. I had used both Landsat and the ESA Ikonos image (04-2001) as base images from which I constructed my map. My color choices were still not finalized, but the composition and layout were satisfactory. How things have changed in a year!


Nikumaroro Atoll - Image

Nikumaroro Atoll - ESA Ikonos Image (04-2001)


Nikumaroro Atoll KR - Marplot Map (1-30,000)

Nikumaroro Atoll - Marplot Map (1:30,000)

With this new revision, I worked exclusively off of the ESA Ikonos image (04-2001). Using Global Mapper, I georectified the image and digitized all of the layers of information from it. I selected my layers and colors within Marplot where I assembled my "nearly" complete map. I viewed it in Irfanview. Satisfied with my preliminary efforts, I moved the map into ImageForge, a freeware drawing program, to add all of my fancy stuff - Legend, Title box, modified Lat/Lon grid, North Arrow. I previewed the map once more using Irfanview. Satisfied with the mapping effort, I uploaded the image into Flickr and posted it into Blogger. As a result of this time, effort and skill all of us ended up with this exquisite map of Nikumaroro Atoll.

View Nikumaroro Atoll on Google Maps

Enjoy!

Monday, July 2, 2007

Nikumaroro Atoll KR - Third Time is the Charm

Nikumaroro Atoll KR - Marplot Map (1-30,000)

Nikumaroro Atoll - Marplot Map (1:30,000)

This is my third time posting this. I received an e-mail from a representative of TIGHAR, a group that has visited this atoll searching for clues to the whereabouts of Amelia Earhart. He asked that I post the following information to discourage visits to the island. The only way one is allowed to visit is with permission of Kiribatian authorities. Read on.

"The best landing place, marked by a white pyramidal concrete structure, is about 0.3 mile S of the village. A boat channel has been cut through the reef in a 054˚ direction and in line with the concrete beacon. Landing should be attempted just after HW when there is less surf than on a rising tide. With a SE wind, landing can be effected in the lee of the wreck at any stage of the tide."

(Sailing Directions Pub-126)

Comment from Pat Thrasher at TIGHAR: The beacon is long gone. It was cleaned off by a storm in 1990 or so. The wreck is gone except for the shell of the triple expansion steam engine. No lee.

BUT. It is completely, utterly ILLEGAL for anyone to land there at all. It is a protected area, bird sanctuary, and about to become a World Heritage Site. No fishing, no landing, no nothing, except as sanctioned by the government of the Republic of Kiribati. We have permission and will have a Customs officer with us. No equipment may be landed without strict adherence to environmental concerns about introduction of insects, bacteria, molds, etc.

Nikumaroro is a sensitive archeological and cultural site. I hope you will discourage landings rather than promoting them with information about when and where to make them!


Nikumaroro Atoll KR

Nikumaroro Atoll (Gardner Island) (4˚40'S., 174˚31'W.) is a wooded, wedge-shaped atoll lying about 137 miles W of Orona Atoll (Hull Island). The atoll is surrounded by a fringing reef, which dries at LW, extending about 0.2 mile offshore. The NW and SE extremities of the reef appears to be extending. Depths off the atoll, which is steep-to except at its NW and SE extremities, average 366m, 0.3 mile from the reef. Nikumaroro Atoll (Gardner Island) encloses a lagoon into which there is no navigable passage. With the exception of two breaks, a large one on the W side and a narrow one on the S side, the land rim of the atoll entirely surrounds the lagoon.

The lagoon is encumbered with coral heads, but seaplanes have landed successfully.

A conspicuous stranded wreck lies close W of the N extremity of the atoll. The wreck was reportedly breaking up.

Tides—Currents.—Off the atoll the set is W, and varies in direction and strength with the prevailing wind. Close inshore, the current follows the trend of the land to the W. There is a deserted village on the W side of the atoll, about 1 mile S of the N extremity, off which anchorage may be obtained by small vessels, very close inshore. Two small beacons N of the village indicate the approach.

Directions.—The best landing place, marked by a white pyramidal concrete structure, is about 0.3 mile S of the village. A boat channel has been cut through the reef in a 054˚ direction and in line with the concrete beacon. Landing should be attempted just after HW when there is less surf than on a rising tide. With a SE wind, landing can be effected in the lee of the wreck at any stage of the tide. The reef is extremely slippery and wide, and the landing is not recommended if any equipment is to be landed or brought off. (SD Pub-126)


This is a redo of a previous post dated 2/25/2006. I wanted to bring in my current colors and include the standard images and maps (1:200,000, 1:100,000, 1:50,000 and 1:25,000). In addition, I wanted to show the Ikonos image that was used to help in digitizing the vectors that makeup this map.

If you have difficulties reading the Flash presentation, go directly to my Flickr account and check out the set of images with the same name as the title of this post.

Enjoy!