Geography of Sri Lanka

Coordinates: 7°00′N 81°00′E / 7.000°N 81.000°E / 7.000; 81.000
Source: Wikipedia, the free encyclopedia.
Sri Lanka
Nickname: Pearl of the Indian Ocean
Map Sri Lanka
Sri Lanka Tamils – 16%, Sri Lankan Moors
– 9%
Map of Asia showing the location of Sri Lanka

Lord Rama.[5]

Sri Lanka's climate includes tropical

.

Geology

More than 90% of Sri Lanka's surface lies on

Gondwanaland.[6] Beginning about 200 million years ago, forces within the Earth's mantle began to separate the lands of the Southern Hemisphere, and a crustal plate supporting both India and Sri Lanka moved toward the northeast.[6] About 45 million years ago, the Indian plate collided with the Asian landmass, raising the Himalayas in northern India, and it continues to advance slowly to the present time.[6] Sri Lanka does not experience earthquakes or major volcanic events because it rides on the center of the plate.[6]

The island contains relatively limited strata of sedimentation surrounding its ancient uplands.

Topography

Topography of Sri Lanka

Extensive faulting and erosion over time have produced a wide range of topographic features.[6] Three zones are distinguishable by elevation: the Central Highlands, the plains, and the coastal belt.[6]

The south-central part of Sri Lanka—the rugged

Central Highlands—is the heart of the country.[6] The core of this area is a high plateau, running north–south for approximately 65 kilometers.[6] This area includes Sri Lanka's highest mountains.[6] (Pidurutalagala is the highest at 2,524 m) At the plateau's southern end, mountain ranges stretch 50 kilometers to the west toward Adam's Peak (2,243 meters) and 50 kilometers to the east toward Namunukula (2,036 m).[6] Flanking the high central ridges are two lower plateaus.[6] On the west is the Hatton Plateau, a deeply dissected series of ridges sloping downward toward the north.[6] On the east, the Uva Basin consists of rolling hills covered with grasses, traversed by some deep valleys and gorges.[6] To the north, separated from the main body of mountains and plateaus by broad valleys, lies the Knuckles Massif: steep escarpments, deep gorges, and peaks rising to more than 1,800 meters.[6] South of Adam's Peak lie the parallel ridges of the Rakwana Hills, with several peaks over 1,400 meters.[6] The land descends from the Central Highlands to a series of escarpments and ledges at 400 to 500 meters above sea level before sloping down toward the coastal plains.[6]

Most of the island's surface consists of plains between 30 and 200 meters above sea level.[6] In the southwest, ridges and valleys rise gradually to merge with the Central Highlands, giving a dissected appearance to the plain.[6] Extensive erosion in this area has worn down the ridges and deposited rich soil for agriculture downstream.[6] In the southeast, a red, lateritic soil covers relatively level ground that is studded with bare, monolithic hills.[6] The transition from the plain to the Central Highlands is abrupt in the southeast, and the mountains appear to rise up like a wall.[6] In the east and the north, the plain is flat, dissected by long, narrow ridges of granite running from the Central Highlands.[6]

Ramanathapuram District) between the Gulf of Mannar (southwest) from the Palk Strait
(northeast).

A coastal belt about thirty meters above sea level surrounds the island.[6] Much of the coast consists of scenic sandy beaches indented by coastal lagoons.[6] In the Jaffna Peninsula, limestone beds are exposed to the waves as low-lying cliffs in a few places.[6] In the northeast and the southwest, where the coast cuts across the stratification of the crystalline rocks, rocky cliffs, bays, and offshore islands can be found; these conditions have created one of the world's best natural harbors at Trincomalee on the northeast coast, and a smaller rock harbor at Galle on the southwestern coast.[6]

Mahaweli Ganga and neighboring streams to create large lakes along their courses.[6] Several hundred kilometers of canals, most of which were built by the Dutch in the 18th century, link inland waterways in the southwestern part of Sri Lanka.[6]

Climate

Sri Lanka map of Köppen climate classification zones
Sri Lanka is the nineteenth most water stressed country in the world.

Sri Lanka's climate can be described as

tropical, and quite hot. Its position between 5 and 10 north latitude endows the country with year-round warm weather, moderated by ocean winds and considerable moisture.[6] The average temperature ranges from a low of 16 °C (60.8 °F) in Nuwara Eliya in the Central Highlands (where frost may occur for several days in the winter) to a high of 32 °C (89.6 °F) in Trincomalee on the northeast coast (where temperatures may reach 38 °C or 100.4 °F).[6] The average yearly temperature for the country as a whole ranges from 28 to 30 °C (82.4 to 86.0 °F).[6] Day and night temperatures may vary by 4 to 7 °C (7.2 to 12.6 °F).[6] January is the coolest month,[6] especially in the highlands, where overnight temperatures may fall to 5 °C (41 °F).[citation needed] May, the hottest period, precedes the summer monsoon rains.[6]

The rainfall pattern is influenced by the monsoon winds of the Indian Ocean and Bay of Bengal and is marked by four seasons.[6] The first is from mid-May to October, when winds originate in the southwest, bringing moisture from the Indian Ocean.[6] When these winds encounter the slopes of the Central Highlands, they unload heavy rains on the mountain slopes and the southwestern sector of the island.[6] Some of the windward slopes receive up to 2,500 mm (98.4 in) of rain per month, but the leeward slopes in the east and northeast receive little rain.[6] The second season occurs in October and November, the intermonsoonal months.[6] During this season, periodic squalls occur and sometimes tropical cyclones bring overcast skies and rains to the southwest, northeast, and eastern parts of the island.[6] During the third season, December to March, monsoon winds come from the northeast, bringing moisture from the Bay of Bengal.[6] The northeastern slopes of the mountains may be inundated with up to 1,250 mm (49.2 in) of rain during these months.[6] Another intermonsoonal period occurs from March until mid-May, with light, variable winds and evening thundershowers.[6]

An increase in average rainfall coupled with heavier rainfall events has resulted in recurrent flooding and related damages to infrastructure, utility supply and the urban economy.[8]

Humidity is typically higher in the southwest and mountainous areas and depends on the seasonal patterns of rainfall.[6] At Colombo, for example, daytime humidity stays above 70% all year, rising to over 90% percent during the monsoon season in June.[6] Anuradhapura experiences a daytime low of 60% during the intermonsoonal month of March, but a high of 79% during the November and December rains.[6] In the highlands, Kandy's daytime humidity usually ranges between 70 and 79%.[6]

Climate data for Colombo, Sri Lanka (1961–1990, extremes 1961–2012)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °C (°F) 35.2
(95.4)
35.6
(96.1)
36.1
(97.0)
35.2
(95.4)
33.2
(91.8)
33.5
(92.3)
32.2
(90.0)
32.2
(90.0)
32.5
(90.5)
33.6
(92.5)
34.0
(93.2)
35.0
(95.0)
36.1
(97.0)
Mean daily maximum °C (°F) 31.0
(87.8)
31.2
(88.2)
31.7
(89.1)
31.8
(89.2)
31.1
(88.0)
30.4
(86.7)
30.0
(86.0)
30.0
(86.0)
30.2
(86.4)
30.0
(86.0)
30.2
(86.4)
30.4
(86.7)
30.7
(87.3)
Daily mean °C (°F) 26.6
(79.9)
26.9
(80.4)
27.7
(81.9)
28.2
(82.8)
28.3
(82.9)
27.9
(82.2)
27.6
(81.7)
27.6
(81.7)
27.5
(81.5)
27.0
(80.6)
26.7
(80.1)
26.6
(79.9)
27.4
(81.3)
Mean daily minimum °C (°F) 22.3
(72.1)
22.7
(72.9)
23.7
(74.7)
24.6
(76.3)
25.5
(77.9)
25.5
(77.9)
25.1
(77.2)
25.1
(77.2)
24.8
(76.6)
24.0
(75.2)
23.2
(73.8)
22.8
(73.0)
24.1
(75.4)
Record low °C (°F) 16.4
(61.5)
18.8
(65.8)
17.7
(63.9)
21.2
(70.2)
20.5
(68.9)
21.4
(70.5)
21.4
(70.5)
21.6
(70.9)
21.2
(70.2)
21.0
(69.8)
18.6
(65.5)
18.1
(64.6)
16.4
(61.5)
Average precipitation mm (inches) 58.2
(2.29)
72.7
(2.86)
128.0
(5.04)
245.6
(9.67)
392.4
(15.45)
184.9
(7.28)
121.9
(4.80)
119.5
(4.70)
245.4
(9.66)
365.4
(14.39)
414.4
(16.31)
175.3
(6.90)
2,523.7
(99.35)
Average precipitation days 5 5 9 14 16 16 12 11 15 17 15 10 145
Average
relative humidity
(%) (at Daytime)
69 69 71 75 78 79 78 77 78 78 76 73 75
Mean monthly sunshine hours 248.0 246.4 275.9 234.0 201.5 195.0 201.5 201.5 189.0 201.5 210.0 217.0 2,621.3
Source 1: NOAA[9] World Meteorological Organization (precipitation only)[10]
Source 2: Deutscher Wetterdienst (extremes)[11]
Climate data for Kandy
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Mean daily maximum °C (°F) 27
(81)
28
(82)
30
(86)
30
(86)
29
(84)
28
(82)
27
(81)
28
(82)
28
(82)
28
(82)
27
(81)
27
(81)
28
(83)
Daily mean °C (°F) 23.1
(73.6)
24.1
(75.4)
25.4
(77.7)
25.9
(78.6)
25.6
(78.1)
24.8
(76.6)
24.3
(75.7)
24.4
(75.9)
24.3
(75.7)
24.3
(75.7)
24
(75)
23.7
(74.7)
24.5
(76.1)
Mean daily minimum °C (°F) 18
(64)
18
(64)
18
(64)
20
(68)
20
(68)
20
(68)
20
(68)
19
(66)
19
(66)
19
(66)
19
(66)
18
(64)
19
(66)
Average precipitation mm (inches) 79
(3.1)
74
(2.9)
71
(2.8)
188
(7.4)
144
(5.7)
132
(5.2)
128
(5.0)
113
(4.4)
155
(6.1)
264
(10.4)
296
(11.7)
196
(7.7)
1,840
(72.4)
Average rainy days 6 5 8 14 11 15 14 13 13 17 16 14 146
Mean daily sunshine hours 7 8 8 7 6 6 6 6 6 6 6 6 7
Source 1: Weather2Travel for highs, lows and sunshine,[12] Climate-Data.org for daily mean temperatures (altitude: 518 m)[13]
Source 2: World Climate Guide,[14] HolidayCheck.com,[15] World Climate[16]

Ecological zones

Precipitation and irrigation map of Sri Lanka

The pattern of life in Sri Lanka depends directly on the availability of rainwater.[6] The mountains and the southwestern part of the country, known as the "wet zone," receive ample rainfall (an annual average of 2500 millimeters).[6] Most of the southeast, east, and northern parts of the country comprise the "dry zone, which receives between 1200 and 1900 mm of rain annually.[6] Much of the rain in these areas falls from October to January; during the rest of the year there is very little precipitation, and all living creatures must conserve precious moisture.[6] The arid northwest and southeast coasts receive the least amount of rain—600 to 1200 mm per year—concentrated within the short period of the winter monsoon.[6]

The natural vegetation of the dry zone has adapted to the annual change from flood to drought.[6] The typical ground cover is scrub forest, interspersed with tough bushes and cactuses in the driest areas.[6] Plants grow very fast from November to February when rainfall is heavy, but stop growing during the hot season from March to August.[6] Various adaptations to the dry conditions have developed.[6] To conserve water, trees have thick bark; most have tiny leaves, and some drop their leaves during this season.[6] Also, the topmost branches of the tallest trees often interlace, forming a canopy against the hot sun and a barrier to the dry wind.[6] When water is absent, the plains of the dry zone are dominated by browns and grays.[6] When water becomes available, either during the wet season or through proximity to rivers and lakes, the vegetation explodes into shades of green with a wide variety of beautiful flowers.[6] Varieties of flowering acacias are well adapted to the arid conditions and flourish on the Jaffna Peninsula.[6] Among the trees of the dry-land forests are some valuable species, such as satinwood, ebony, ironwood, and mahogany.[6]

In the wet zone, the dominant vegetation of the lowlands is a tropical evergreen forest, with tall trees, broad foliage, and a dense undergrowth of vines and creepers.[6] Subtropical evergreen forests resembling those of temperate climates flourish in the higher altitudes.[6] Montane vegetation at the highest altitudes tends to be stunted and windswept.[6]

Forests at one time covered nearly the entire island, but by the late 20th century lands classified as forests and forest reserves covered only one-fifth of the land.

Mahaweli Ganga Program of the 1970s and 1980s in northern Sri Lanka, the government set aside four areas of land totalling 1,900 km2 as national parks.[6]

Land use and settlement patterns

Diagrammatic section across Sri Lanka as per D. N. Wadia[17]

The dominant pattern of human settlement during the last 2,500 years has consisted of village farming communities.[6] Even in the 1980s, the majority of people lived in small villages and worked at agricultural pursuits.[6] Traditional farming techniques and life-styles revolve around two types of farming--"wet" and "dry"—depending upon the availability of water.[6]

The typical settlement pattern in the rice-growing areas is a compact group of houses or neighborhood surrounding one or several religious centers that serve as the focus for communal activities.[6] Sometimes the houses may be situated along a major road and include a few shops, or the village may include several outlying hamlets.[6] The life-sustaining rice fields begin where the houses end and stretch into the distance.[6] Some irrigated fields may include other cash crops, such as sugarcane, or groves of coconut trees.[6] Palmyra trees grow on the borders of fields or along roads and paths.[6] Individual houses also may have vegetable gardens in their compounds.[6] During the rainy seasons and thereafter, when the fields are covered by growing crops, the village environment is intensely verdant.[6]

The nature of agricultural pursuits in Sri Lanka has changed over the centuries and has usually depended upon the availability of arable land and water resources.

irrigation works in ancient Sri Lanka.[6]

Beginning in the 16th century and culminating during the

rubber, tea, or cinnamon.[6] It also brought about a changed life-style, as the last hunting-and-gathering societies retreated into smaller areas and laborers moved into the highlands to work on plantations.[6] Through the late 20th century, workers on large plantations lived in villages of small houses or in "line rooms" containing ten to twelve units.[6] The numerous plantations of small landholders frequently included attached hamlets of workers in addition to the independent houses of the plantation owners.[6]

Aerial view of the Southern Province showing the land use patterns of the coastal belt.
Detailed map of Sri Lanka

The coastal belt surrounding the island contains a different settlement pattern that has evolved from older fishing villages.[6] Separate fishing settlements expanded laterally along the coast, linked by a coastal highway and a railway. The mobility of the coastal population during colonial times and after independence led to an increase in the size and number of villages, as well as to the development of growing urban centers with outside contacts.[6] In the 1980s, it was possible to drive for many kilometers along the southwest coast without finding a break in the string of villages and bazaar centers merging into each other and into towns.[6]

Statistics

Land use (2018): 20.7% arable land, 15.8% permanent crops, 7% permanent pasture, 29.4% forest, 27.1% other.[1]

Irrigated land: 5,700 km2 (2012)[1]

Total renewable water resources: 52.8 cubic km[1]

Natural hazards: occasional cyclones and tornadoes[1]

Environmental issues: deforestation; soil erosion; wildlife populations threatened by poaching and urbanization; coastal degradation from mining activities and increased pollution; freshwater resources being polluted by industrial wastes and sewage runoff; waste disposal; air pollution in Colombo[1]

Maritime claims

  • contiguous zone: 24 nmi (44.4 km; 27.6 mi)[1]
  • continental shelf: 200 nmi (370.4 km; 230.2 mi) or to the edge of the continental margin[1]
  • exclusive economic zone: 200 nmi (370.4 km; 230.2 mi)[1]
  • territorial sea: 12 nmi (22.2 km; 13.8 mi)[1]

See also

References

  1. ^ a b c d e f g h i j k l m n o "Sri Lanka". The World Factbook. Central Intelligence Agency. May 11, 2021. Retrieved May 14, 2021. Public Domain This article incorporates text from this source, which is in the public domain.{{cite web}}: CS1 maint: postscript (link)
  2. ^ "Joshua Calder's World Island Info – Largest Islands of the World". Worldislandinfo.com. Retrieved 2016-01-30.[unreliable source?]{{cite web}}: CS1 maint: postscript (link)
  3. ^ www.jpp.co.jp https://www.jpp.co.jp/lanka/geo/geote/geo05e.htm. Retrieved 2023-04-14. {{cite web}}: Missing or empty |title= (help)
  4. ^ Manimaran, G. (2008-08-01). "Geoenvironmental Scenario on the Landward Migration of Thamiraparani Microlithic Culture to Sri Lanka Through Adam's Bridge". Journal of the Geological Society of India. 72: 222–224..
  5. ^ "Adam's bridge". Encyclopædia Britannica. 2007. Archived from the original on 13 January 2008. Retrieved 14 September 2007.
  6. ^
    OCLC 311429237. Public Domain This article incorporates text from this source, which is in the public domain.{{cite encyclopedia}}: CS1 maint: postscript (link
    )
  7. ^ Pathirana, H.D.N.C., 1980, Geology of Sri Lanka in relation to Plate Tectonics; L. Natn. Sci. Coun. Sri Lanka v. 8, p. 75-85
  8. ^ Integrating urban agriculture and forestry into climate change action plans: Lessons from Sri Lanka, Marielle Dubbeling, the RUAF Foundation, 2014
  9. ^ "Colombo Climate Normals 1961–1990". National Oceanic and Atmospheric Administration. Retrieved November 19, 2016.
  10. ^ "World Weather Information Service – Colombo". World Meteorological Organization. Archived from the original on February 18, 2017. Retrieved November 19, 2016.
  11. ^ "Klimatafel von Colombo (Kolamba) / Sri Lanka (Ceylon)" (PDF). Baseline climate means (1961–1990) from stations all over the world (in German). Deutscher Wetterdienst. Archived from the original (PDF) on 16 April 2019. Retrieved November 19, 2016.
  12. ^ "Best Weather in Kandy, Sri Lanka". Weather2Travel. Retrieved 12 November 2013.
  13. ^ "Climate: Kandy CP (altitude: 518 m) – Climate graph, Temperature graph, Climate table". Climate-Data.org. Retrieved 12 December 2013.
  14. ^ www.worldclimateguide.co.uk. "Kandy Climate Guide, Sri Lanka – World Climate Guide".
  15. ^ Temperature Kandy – climate Kandy Sri Lanka (Inside) – weather Kandy Archived 25 January 2013 at archive.today
  16. ^ "World Climate: N07E080 – Weather history for travel real estate and education".
  17. ^ Darashaw Nosherwan Wadia (1943). "Records of the Department of Mineralogy, Ceylon". {{cite journal}}: Cite journal requires |journal= (help)

7°00′N 81°00′E / 7.000°N 81.000°E / 7.000; 81.000