Saturday, September 21, 2013

Geography of Maldives

Maldives is a country of South Asia, situated in the Indian Ocean, south-southwest of India. It consists of approximately 1,190 coral islands grouped in a double chain of 26 atolls, spread over roughly 90,000 square kilometers, making this one of the most disparate countries in the world. Composed of live coral reefs and sand bars, the atolls are situated atop a submarine ridge 960 kilometers long that rises abruptly from the depths of the Indian Ocean and runs from north to south. Only near the southern end of this natural coral barricade do two open passages permit safe ship navigation from one side of the Indian Ocean to the other through the territorial waters of Maldives. For administrative purposes the Maldives government organized these atolls into nineteen administrative divisions.
The largest island of Maldives is Gan, which belongs to Laamu Atoll or Hahdhummathi Maldives. In Addu Atoll the westernmost islands are connected by roads over the reef and the total length of the road is 14 km.
Most atolls of the Maldives consist of a large, ring-shaped coral reef supporting numerous small islands. Islands average only one to two square kilometers in area, and lie between one and 1.5 meters above mean sea level. Although some of the larger atolls are approximately 50 kilometers long from north to south, and 30 kilometers wide from east to west, no individual island is longer than eight kilometers.
The Maldives has no hills, but some islands have dunes which can reach 2.4 meters (8 feet) above sea level, like the NW coast of Hithadhoo (Seenu Atoll) in Addu Atoll. Islands are too small to have rivers, but small lakes and marshes can be found in some of them.
On average, each atoll has approximately 5 to 10 inhabited islands; the uninhabited islands of each atoll number approximately 20 to 60. Some atolls, however, consist of one large, isolated island surrounded by a steep coral beach. The most notable example of this type of atoll is the large island of Fuvahmulah situated in the Equatorial Channel.
The tropical vegetation of Maldives differs in the inhabited and in the uninhabited islands. Inhabited islands have small groves of banana, papaya, drumstick and citrus trees by the homesteads, while breadfruit trees and coconut palms are grown in available patches of land. On the other hand uninhabited islands have mostly different kinds of bushes (magū, boshi) and mangroves (kuredi, kandū) along the waterline as well as some coconut trees.
Some islands are marshy, while others are higher owing to sand and gravel having been piled up by wave action. Often the soil is highly alkaline, and a deficiency in nitrogen, potash, and iron severely limits agricultural potential. Ten percent of the land, or about 26 km², is cultivated with taro, bananas, coconuts, and other fruit. Only the lush island of Fuvammulah produces fruits such as oranges and pineapples - partly because the terrain of Fuvammulah sits higher than most other islands, leaving the groundwater less subject to seawater penetration. However, as population grows, even in this island the cultivated areas are shrinking rapidly.

Freshwater floats in a layer known as "Ghyben/Herzberg lens" above the seawater that permeates the limestone and coral sands of the islands. These lenses are shrinking rapidly on Male and on many islands where there are resorts catering to foreign tourists. Mango trees already have been reported dying on Male because of salt penetration. Most residents of the atolls depend on groundwater or rainwater for drinking purposes.
The temperature of Maldives ranges between 24 and 33 °C (75.2 and 91.4 °F) throughout the year. Although the humidity is relatively high, the constant sea breezes help to keep the air moving. Two seasons dominate Maldives' weather: the dry season associated with the winter northeast monsoon and the rainy season brought by the summer southwest monsoon. The annual rainfall averages 2,540 millimeters (100 in) in the north and 3,810 millimeters (150 in) in the south.
The weather in Maldives is affected by the large landmass of the South Asia to the north. The presence of this landmass causes differential heating of land and water. Scientists also cite other factors in the formation of monsoons, including the barrier of the Himalayas on the northern fringe of the South Asia and the sun's northward tilt, which shifts the jet stream north. These factors set off a rush of moisture-rich air from the Indian Ocean over the South Asia, resulting in the southwest monsoon. The hot air that rises over the South Asia during April and May creates low-pressure areas into which the cooler, moisture-bearing winds from the Indian Ocean flow. In Maldives, the wet southwest monsoon lasts from the end of April to the end of October and brings the worst weather with strong winds and storms. In May 1991 violent monsoon winds created tidal waves that damaged thousands of houses and piers, flooded arable land with seawater, and uprooted thousands of fruit trees. The damage caused was estimated at US$30 million.