LANDSCAPE OF SL

Coastal Plain: $0{-}30\,\text{m}$ above sea level; narrow in South (\approx $3\,\text{km}$ ), wider in North (\approx $32\,\text{km}$ ); features include lagoons, bays, deltas, sand dunes, marshes
Intermediate Plain: $30{-}300\,\text{m}$ ; broader in North; contains residual hills (e.g.
Ritigala), undulating lands, flood-plains
Central Mountains: >300\,\text{m}; four main ranges (Samanala, Namunukula, Pidurutalagala–Kirigalpotta, Knuckles); five plateaus (Kandy, Hatton, Welimada, Mahawelatenna, Koslanda); passes (Balana, Haputale); highest peak Pidurutalagala $2524\,\text{m}$ ; numerous waterfalls

$103$ river valleys; $34$ perennial (origin in highlands), remainder seasonal
Longest & largest basin: Mahaweli Ganga – length $335\,\text{km}$ , catchment $10\,327\,\text{km}^2$ (≈ $\tfrac16$ of island)
General pattern: radial from central hills; tributaries create dendritic & trellis sub-patterns
$80\%$ of rivers cross the dry zone; short Western rivers (Kelani, Kalu) give flash floods in rainy seasons

Location near equator ⇒ high temperatures; mean annual $27^{\circ}\text{C}$
Lapse rate: temperature drops with altitude (e.g. Kandy $447\,\text{m}$ $24.4^{\circ}\text{C}$ → Pidurutalagala $2524\,\text{m}$ $11.5^{\circ}\text{C}$ )
Rainfall mechanisms
• Convectional: dominant in inter-monsoon periods (Mar–Apr, Oct–Nov); afternoon thunderstorms
• Monsoonal: South-West (May–Sep) wets W/SW slopes; North-East (Dec–Feb) wets N/E dry zone
• Cyclonic: Bay of Bengal systems, peak Nov–Dec, add rain mainly N & E

Low-country Wet: rainfall >2000\,\text{mm}; no true dry season
Low-country Dry: $1250{-}2000\,\text{mm}$ ; distinct dry spell, rain mainly from NE monsoon/cyclones
Hill-country Wet: Western slopes >3000\,\text{mm}; coolest temps
Hill-country Dry: Eastern slopes $1750{-}2000\,\text{mm}$ ; leeward of SW monsoon
Semi-arid: Mannar & Hambantota belts $650{-}1250\,\text{mm}$ ; high evaporation

Tropical Wet Evergreen Forests: SW lowlands (e.g. Sinharaja); tall $30{-}40\,\text{m}$ , dense canopy, high biodiversity
Dry Mixed Evergreen Forests: low-country dry zone; $20{-}30\,\text{m}$ hardwoods (teak, palu)
Intermediate Evergreen Forests: transitional belt; mixed species $10{-}25\,\text{m}$
Hill-country Wet Forests: >1200\,\text{m} W slopes; short $8{-}10\,\text{m}$ cloud forests
Hill-country Dry (Patanas): >1400\,\text{m} E slopes; grasslands with stunted, wind-shaped trees
Thorn & Scrub: semi-arid NW & SE; xerophytic shrubs, cactus
Mangroves: estuaries/lagoons; prop-rooted species (kadol, kirala)

Total population $\approx20.2\,\text{million}$ (2012); density average $323\,/\,\text{km}^2$ but highly uneven
Highest density: Colombo $3305\,/\,\text{km}^2$ ; lowest: Moneragala $72\,/\,\text{km}^2$
Composition: Sinhalese $74.9\%$ , Sri Lankan Tamil $11.2\%$ , Muslim $9.2\%$ ; religions: Buddhist $70.2\%$ , Hindu $12.6\%$ , Islam $9.7\%$
Sex ratio 2012: $94.3$ males per $100$ females; ageing share (\ge $60$ yrs) rose from $6.6\%$ (1981) to $12.4\%$ (2012)
Settlement types: rural (agro/fishing based), urban (non-agricultural, dense), rurban (mixed peri-urban)

Agriculture: paddy, chena, tea (highlands), coconut, rubber, fisheries, livestock
Industry: concentrated Western Province; FTZs at Katunayake, Biyagama, Koggala; products include apparel, plastics, tyres
Services: education, health, transport, utilities; fastest-growing employment share

Roads: national widening, flyovers, expressways; goal – island-wide day travel
Electricity: hydro (Mahaweli, Kelani, Kalu, Walawe), thermal, rising renewable (solar)
Water: sourced from rivers, tanks, groundwater; critical for domestic, agriculture, industry – conservation essential

Coastal plain: supports fisheries, ports, tourism, coir, mineral extraction (limestone, sand)
Wet zone: high population, plantation & mixed farming, dense road/industry network
Dry zone: tank-based irrigation enables paddy, chena; ancient cities & reservoirs
Hill country: tea estates, hydropower, tourism; roads built with hairpin bends to manage steep relief
Jaffna Peninsula: limestone terrain, arid climate → well irrigation, palmyrah-based products, tobacco/vegetable gardens, fishing around islands