EVS-Islands

Tureia Atoll (20˚49'S., 138˚32'W.) 7 miles long and 5.5 mile wide, is low and wooded except on the SE side; the lagoon is not accessible. Landing at the village on the N side is dangerous and requires the use of a surf boat.

(SD Pub-126)

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This small atoll in the southern Tuamotu Archipelago is located at 20°50’ south latitude by 138°33’ west longitude. It covers an area of 8.3 square kilometers (3.2 sq. miles). Tureia Atoll is 115 kilometers (71.5 miles) from the atoll of Moruroa and 1,190 kilometers (739 miles) from Papeete. This diamond-shaped atoll is a maximum length of 13 kilometers (8.1 miles) and a maximum width of 7.4 kilometers (4.6 miles). It covers an area of 4,721 hectares (11,665 acres). There is no pass through the surrounding coral reef. The biggest islet, or motu, is located along the northwest coast and measures 22.5 kilometers (14 miles) long by and 250 meters (820 ft.) wide, running from the east coast to the south coast. There also are 27 small motu along the east coast with a total land area of 835 hectares (2,063 acres).

British Captain Edward Edwards, who was looking for the famous “HMS Bounty” mutineers, was the first European to discover Tureia in 1791. This atoll is the administrative center for a district with a population of 1,321 persons (1996 census). A full meteorological station began operation here since 1967, going automatic within the weather station network in June 1987. The station began measuring rainfall in January 1990, an operation that ended in March 1996 with its closing down.

A road from the village of Hakamaru to the north circles the atoll as far as the south. Other roads provide access to the coconut tree plantation, an aerodrome south of the village and a former Pacific Nuclear Testing Center camp made up of 20 facilities, including shelters and several water tanks, all of which have since been abandoned by the French Army.

Information from Presidency of French Polynesia

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This is a redo of a very early effort. My first attempt was completed over 2 years ago. I deleted it as I was developing this version. Using Landsat imagery is great for constructing shoreline details resolved to a certain level (+/- 14.5 meters). However, the determination of type of vetation groundcover is tricky at best. One really needs to personally view the island's flora to make an accurate determination. What a job!

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 11/03/2006 07:00:00 AM | Permalink | Comments | links to this post

Akiaki (Aki Aki, Thrum Cap) [1790] (18˚33'S., 139˚13'W.), NW of Vahitahi, is a small island of coral formation. There is a landing on the NW side that is difficult.

(SD Pub-126)

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Group: Centre East Group Archipelago: Tuamotu Archipelago Country: France - French Polynesia - Tuamotu Is. Region: Oceania 18 Lat: 18.56º S Long : 139.21º W Area: 1.3 sq. km Altitude: ? m Depth to nearest land: 3000 m Nearest island: 43.4 km @ 123° (Atoll Vahitahi) Group: 940 km Nearest continent: South America Distance: 5500 km Isolation Index: 112 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, visited occasionally 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

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This small island claims to be an atoll. It is reported to be visited occassionally to work the coconut trees that are planted on it. I believe that the populated island is Vahitahi and these are the people that visit Akiaki. There is still hope for the nomadic lifestyle.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 11/03/2006 06:50:00 AM | Permalink | Comments | links to this post

Ponam Island was a fast project. I saw the image of Manus Island (large island to the south) and picked off one of the small islands that fringe the large island. As you can see, Ponam Island is reef fringed. The mother country is Papua New Guinea (PP).

Enjoy!

Labels: EVS, island, Landsat, map, Marplot, New Guinea, Pacific, Papua, reef

Posted by Mr Minton at 11/03/2006 06:45:00 AM | Permalink | Comments | links to this post

Kaukura Atoll's EVS Layers

This post is all about EVS layers of information. You might want to pause it between slides and read my notes below the first time through. The next time, view it at a faster speed. So lets discuss the various layers used on this island.

The first 3-slides are for orientation purposes. Kaukura Atoll is located in the Tuamotus. It is a medium sized atoll.

Slide 4 - EVS Ocean Mask - I always place the atolls onto an ocean mask. Marplot has either a white or black background. Both not very practical to display an island on.

Slide 5 - EVS Shoreline - My shorelines were extracted from Landsat imagery.  This layer is one of my core layers.  It is the reason I make maps in the first place.

Slides 6 & 7 - EVS Land Island & EVS Airfield - The Land Island fills out the island giving it some land to view.  If the island I am mapping is high, often this is the only additional land layer I will include, since I do not include elevations. 

Slides 8 thru 13 - EVS Vegetation Layers - Althought the identification of vegetation from Landsat is relatively easy, to determine the density of that vegetation is difficult.  My EVS Vegetation layers are as consistently identified as I am able to visually do.  One of the difficult layers is the EVS Vegetation Wetlands.  These tend to show up as a darker shade of green on the base image.

Slides 14 & 15 - EVS Land Bare & Land Sand - These layers define vegetation free areas.  Land Bare is darker colored whereas Land Sand is most often white to shades of white.

Slides 16 thru 20 - EVS Reef Layers - The challenge with reefs is to determine depth of water based on what is visible.  The reef that is lighter in color I classify as EVS Reef Shallow.  As the color of the reef gets darker, I attempt to delineate logical divisions between various depths.  My final reef is called EVS Reef Deep which is the darkest area within the lagoon.

These are some of the decisions I have to make as I construct my maps of islands.  I strive for consistency and as clean and sharp a delineation as possible between layers.

Enjoy!

Posted by Mr Minton at 11/01/2006 10:20:00 PM | Permalink | Comments | links to this post

Crash! Boom! Bang!

I currently live in mostly sunny California, but I have resided in places where the sky cracks and rumbles - places of thunder and lightning.

NASA has an ongoing effort to collect Lightning data for a number of years. They include, on their site, a number of datasets which includes some excellent raster image maps.

Based on the map above, if you want to study lightning, go to central Africa. Interestingly, the Kashmir Region between India and Pakistan appears to rumble with high intensity as well.

Included is an interesting QT movie that shows 7-years of global lightning data. You will appreciate our living planet after viewing the movie.

Explore NASA's site, you will not be disappointed.

Enjoy!

Labels: lightning, map, NASA, thunder

Posted by Mr Minton at 11/01/2006 06:33:00 AM | Permalink | Comments | links to this post