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பரீட்சைக்கு முன் விரைவு மீட்டல் — 5 நிமிடம் / 15 நிமிடம் / முந்தின நாள் அடுக்குகள். எல்லையைத் தெரிவு செய்: ஒரு தரம் அல்லது முழுப் பாடத்திட்டமும்.

முழுமை தரம் 10 தரம் 11

⚠ என் தவறுகளைப் பயில் 📝 இவ்வெல்லை வினாடி வினா

தரம் 11 — மீட்டல்

அலகு 1 — புவியின் இயற்கை வளங்கள்

Resource = Nature + Utility. இரண்டுமே வேண்டும்.
2 வகை: Renewable (நீர், காற்று, சூரியன், காடு) vs Non-renewable (coal, oil, metal, uranium).
3 பாறை வகை: தீப்பாறை (igneous — granite/basalt) · படிவுப்பாறை (sedimentary — limestone/sandstone/coal/oil) · உருமாறிய (metamorphic — marble/quartzite/graphite/slate).
உலோக கனியம்: iron (China #1), copper (Chile), bauxite (Australia), gold (China), tin, silver, uranium.
உலோகமற்ற கனியம்: limestone, gypsum, graphite (SL வேய்ன் graphite உலகின் சிறந்த தர), salt, diamond, gems (SL blue sapphire).
5 காட்டு வலயம்: Tropical rainforest (Amazon — largest) · Savanna · Deciduous · Coniferous/Taiga (Russia+Canada) · Tundra.
மண் 5 அடுக்கு: O (organic) · A (topsoil — most fertile) · B (subsoil) · C (weathered rock) · R (bedrock).
நீர் பகிர்வு: 97.5% உப்பு + 2.5% இனிப்பு (70% ice). வெறும் 0.7% usable.
நீர்ச் சுழற்சி 5 step: Evaporation → Transpiration → Condensation → Precipitation → Runoff. Sun = energy driver.
நீர் பயன் %: Agriculture 70% · Industry 20% · Domestic 10%.
பாதுகாப்பு: Sustainable Development (Brundtland 1987) + 3R (Reduce > Reuse > Recycle) + Paris Agreement 2015 (1.5°C) + SDGs (6/7/13/14/15).

அலகு 2 — இலங்கையின் இயற்கை வளங்கள்

SL land 65,610 km²; EEZ 517,000 km² (7×). Coast 1,340 km.
நீர்: SW (May-Sep) + NE (Oct-Feb) monsoons. Avg ~1860 mm. Wet zone 5000+, dry <1250.
103 ஆறுகள். Mahaweli 335 km (longest); Kelani 145; Walawe 138.
4000+ ancient tanks. Parakrama Samudra (Polonnaruwa, 2500 ha) largest ancient; Senanayake Samudra (Gal Oya, 1950s) largest modern.
காடு 29% (84% in 1881). UNESCO: Sinharaja (1988) + Central Highlands (2010 — Horton Plains + Knuckles + Peak Wilderness).
NPs: Yala (leopard density world #1), Wilpattu (largest area), Wasgomuwa, Horton Plains, Bundala (Ramsar), Udawalawe (elephants), Minneriya (gathering).
மண்: RBE (dry zone), RYP (wet zone hills), Alluvial (rivers), Solonchak (coast), Lithosol (mountain). 14 types.
Graphite: Bogala/Kahatagaha/Ragedara — world's highest purity vein (95-98%).
Gems: Ratnapura "City of Gems"; SL world #1 for Cat's Eye + Blue Sapphire.
Mineral sands: Pulmoddai (Trincomalee NE) — ilmenite, rutile, zircon, monazite. LMSL.
Limestone: Aruwakkalu (Puttalam) — Holcim cement.
Phosphate: Eppawala. Salt: Hambantota+Puttalam pans.
Energy mix: coal 35% + hydro 30% + oil 20% + RE 15%. Target 70% RE by 2030.
Norochcholai coal 900 MW (CMEC 2011). Mahaweli hydro Victoria 210 MW. Mannar wind 100 MW.
Sapugaskanda oil refinery (1969, 50,000 bpsd).

அலகு 3 — உலக சனத்தொகை

உலக சனத்தொகை = புவியில் வாழும் மக்களின் மொத்தம். 2024 = 8 பில்லியன் (800 கோடி).
2 அவசியம்: வளப் பகிர்வு + கொள்கை வகுப்பு.
Billion milestones: 1800=1B · 1930=2B · 1960=3B · 1987=5B · 1999=6B · 2011=7B · 2024=8B. 2050 ~11B.
Time per billion: 1→2B = 130 yrs. Recent additions = 12-13 yrs each.
Growth shape: J-curve (\"சனத்தொகை வெடிப்பு\").
Growth driver: அபிவிருத்தியடையும் நாடுகள் (Africa, South Asia).
கண்டம் %: Asia 60 · Africa 16 · Europe 10 · N.Am 8 · S.Am 5 · Australia 1.
Top 2 (2014): China 19.24% + India 17.50% = 37%.
Distribution factors: Physical (climate, terrain, soil, water, resources) + Human (industry, transport, urban, history, politics).
3 dense belts: S/E Asia · W/C Europe · NE US coast.
3 sparse: Deserts (Sahara/Arabia/Kalahari/Atacama) · Polar (Antarctica/Greenland/Siberia) · Mountains (Himalaya/Andes).

அலகு 4 — இலங்கையின் சனத்தொகை

2012 = 20.3M; density 323/km²; first census 1871 = 2.4M.
1953 peak NI 2.8% (malaria eradication DDT death rate↓).
2012 NI = 0.7% (female ed + family planning); TFR ~2.0.
District extremes: Colombo = highest pop (2.3M) + highest density (3438). Mullaitivu = lowest density (92).
Sector: Rural 77.3% · Urban 18.2% · Estate 4.4%.
Ethnic: Sinhala 74.9 · SL Tamil 11.2 · SL Moor 9.2 · Indian Tamil 4.2 · Others 0.5.
Religion: Buddhist 70.2 · Hindu 12.6 · Islam 9.7 · Christian 7.4.
Age: 0-14=25.6 · 15-59=62.2 · 60+=12.2.
Gender: F 51.5% · M 48.5%.
Push: unemployment, war, drought. Pull: jobs, education, peace.
Mahaweli planned resettlement: ~1M wet→dry zone (1977+).
External migration: Middle East 1.5M workers (60% female); diaspora 1M+ post-1983.

அலகு 5 — அபிவிருத்தி

Development = multi-dimensional well-being (economic + social + environmental + freedom).
Old view: GDP/industrial growth only. New view (UNDP 1990): HDI multi-dim.
Amartya Sen (1999) "Development as Freedom" — capabilities approach.
Indicators 3 types: Economic (GDP/GNI/income/growth) · Social (life exp/IMR/literacy) · Environmental (CO₂/forest/EPI).
HDI (UNDP 1990) — 3 dim: Health (life exp) + Knowledge (schooling) + Living (GNI). Scale 0-1.
HDI categories: Very High >0.8 · High 0.7-0.8 (SL=0.78) · Medium 0.55-0.7 · Low <0.55.
PQLI (Morris 1979) — IMR + Life exp at 1 + Literacy. Scale 0-100.
Sustainable Development: Brundtland 1987 — "meet present needs without compromising future."
3 pillars: Economic + Social + Environmental.
SDGs 2015-2030: 17 goals (replaced MDGs 2000-2015 8 goals).
NICs: S.Korea + Taiwan + Singapore + HK (Asian Tigers).
LDCs: 46 UN-classified least developed countries.

அலகு 6 — உலகில் இயற்கை இடர்கள்

Hazard vs Disaster: Hazard = natural event; Disaster = hazard + vulnerable population.
Risk = Hazard × Vulnerability × Exposure ÷ Capacity.
Earthquake: Plate tectonics; ~7 major plates. 3 boundaries: Convergent + Divergent + Transform. Pacific Ring of Fire = 80% quakes. Richter logarithmic.
Volcano: 3 states (Active/Dormant/Extinct). 75% in Pacific Ring of Fire. VEI 0-8 scale.
Tsunami: "Harbour wave." Deep ocean 700-800 km/h but 1m height; shallow shore 10-50m.
2004 Boxing Day Tsunami: M9.1 off Sumatra → 14 countries, ~230K dead. SL 35K+. IOTWS established 2006.
2011 Tohoku: M9.1 → Fukushima nuclear meltdown.
Cyclone names: Cyclone (Indian Ocean) / Hurricane (Atlantic) / Typhoon (NW Pacific).
Formation: SST 26.5°C+, latitude 5-20° (NOT equator), low shear, moisture.
Saffir-Simpson Cat 1-5. Cat 5 = 252+ km/h.
Deadliest cyclone: 1970 Bhola Bangladesh ~300-500K dead.
Deadliest natural disaster ever: 1931 Yangtze flood ~4M dead.
Sendai Framework 2015-2030 4 priorities.
Disaster Mgmt Cycle: Mitigation → Preparedness → Response → Recovery.

அலகு 7 — இலங்கையில் இயற்கை இடர்கள்

SL = stable plate interior: no major earthquakes/volcanoes. Subject to floods, landslides, droughts, cyclones, tsunami (2004), lightning, coastal erosion.
Floods: Kelani, Kalu (Ratnapura most frequent), Nilwala, Mahaweli, Walawe. Causes: monsoons + deforestation + urban.
Landslides: 10 districts (Nuwara Eliya, Kandy, Badulla, Ratnapura, Matale, Kegalle, Kalutara, Galle, Matara, Hambantota). ~30% of land vulnerable.
Deadliest landslide: 2016 Aranayake (Kegalle) — 127 dead. Others: 1986 Walapane 122; 2014 Meeriyabedda 38.
NBRO = landslide research + warning.
Droughts: Dry zone NCP + Hambantota + Monaragala. 2016-17 major (2M+ affected).
Cyclones: Eastern + Northern. 1978 deadliest 700+ dead, 1M displaced. 1964, 2016 Roanu, 2024 Remal.
Tsunami 2004: M9.1 Sumatra → SL ~35K+ dead. Peraliya train ~1,700 dead — deadliest train disaster.
Lightning: SL world's highest casualties per capita — ~50+ deaths/yr.
DM Act 2005 post-tsunami. NCDM (President-chaired). DMC operational.
Sendai Framework 2015-30 + National DRM Plan 2018-30.
NNDIS = National Natural Disaster Insurance Scheme (SLIC).
Cycle: Mitigation → Preparedness → Response → Recovery.

அலகு 8 — காலநிலை மாற்றங்கள்

Weather (short) vs Climate (30yr avg) vs Climate Change (multi-decade shift).
Natural greenhouse effect essential: Earth +15°C vs -18°C without it.
Enhanced (human) effect = problem. CO₂ 280→425+ ppm; global temp +1.1°C above pre-industrial.
Main GHGs: CO₂ (75% emissions), CH₄ methane (84× GWP, 12 yr lifetime), N₂O (273× GWP), F-gases (1000-23000×).
Emissions by sector: Energy 75% + Agriculture/Land 20% + Industry/Waste 5%.
Per capita CO₂: Qatar 37, USA 14, China 7.5, EU 6, India 1.9, SL 1, Burundi 0.05.
Observed effects: +1.1°C, Arctic ice loss 13%/decade, sea level +25cm, more extreme weather, coral bleaching, ecosystem stress.
UNFCCC 1992 Rio + IPCC 1988 + COP annual.
Kyoto Protocol 1997: binding developed-country targets only.
Paris Agreement 2015 (COP21): Universal; 1.5°C target; NDCs every 5yr; $100B/yr finance; net-zero 2050.
Montreal Protocol 1987: CFC ban — most successful environmental treaty.
SL NDC 2021: 14.5% reduction by 2030; 70% RE by 2030; carbon neutral 2050.
Mitigation (reduce GHG) vs Adaptation (cope with impacts).

அலகு 9 — 1:50,000 இலங்கையின் இடவிளக்கப் படங்கள்

SL 92 topographic sheets @ 1:50,000. 1 cm = 500m; 2 cm = 1 km; 1 cm² = 0.25 km².
Each sheet: 5'×5' graticule; ~9km × 9km ground; ~80cm × 80cm map.
5 reading steps: title+sheet → scale → adjacent sheets → key → grid+north → face.
Grid System: Eastings FIRST (vertical lines, read L→R); Northings (horizontal lines, read bottom→top). "Along corridor, then up stairs."
4-fig grid ref: 1km×1km square. e.g., "34 56".
6-fig grid ref: ~100m × 100m point. Format EEEnnn. e.g., "346 563".
Contours = brown. CI = 10 or 20m. Index contour every 5th = thicker + labeled.
Close contours = steep; spaced = gentle. Concentric closed = peak.
V up-slope = ridge; V down-slope = valley.
Drainage patterns: Dendritic (common SL), Trellis (folded), Rectangular (jointed), Radial (volcanic), Centripetal (basin), Parallel (slope), Annular (dome), Deranged (glaciated).
Colors: Blue=water; Brown=contour+dam; Red=roads+admin; Black=rail+settlement; Green=paddy; Yellow=plantation+track.
Road classes: A=double red solid; B=single red solid; C/D=dashed red.
Area calc: regular = L×B×0.25 km². Irregular = square count (full + half-squares).
Gradient: rise/run. 1:5=20% very steep; 1:100=1% gentle.
Cross-section: vertical profile along line; use ~10× vertical exaggeration.

அலகு 10 — தரவுகளை விளக்குவதற்காக வரைபுகளைப் பயன்படுத்தல்

Graph choice matrix: Trend over time = Line; Compare categories = Bar; Proportion = Pie; Climate = Climograph; Correlation = Scatter; Spatial = Choropleth.
Line graph: X=time + Y=value. Best for continuous data trend.
Bar chart: compare categories. Simple/multiple/stacked/horizontal/100%.
Pie chart: proportional composition. Sum=100%. Angle = (value/total) × 360°. Max 7 categories.
Climograph: temperature line (left Y-axis) + rainfall bars (right Y-axis) × 12 months.
Scatter plot: correlation between 2 variables. Positive/negative/no.
Histogram: frequency distribution of continuous data binned.
Choropleth map: spatial data; regional shading by value.
Cartogram: map distorted by data (size proportional to variable).
Pictograph: repeated icons proportional to value.
Population pyramid: back-to-back horizontal bars (age-sex structure).
Every graph must have: title + axes labels with units + scale + source.
Avoid: 3D effects, truncated axes, wrong graph type, too many categories.

அலகு 1 — புவியின் இயற்கை வளங்கள்

Resource definition — விரிவாக: இயற்கையில் கிடைக்கும் + மனிதனுக்கு utility இருக்க வேண்டும். Sahara sand = construction-க்கு பயன்பட்டபோதே வளம். Petroleum — fuel utility தோன்றியதிலிருந்தே வளம்.
Renewable vs Non-renewable — விரிவாக: Renewable = water/wind/sun/forest/fish/soil (மிக மெதுவாக). Non-renewable = fossil fuels (millions of years; oil ~50, coal ~150 reserves), metals, uranium. Forest over-exploited → effectively non-renewable. Sustainable yield = use ≤ regeneration.
பாறை — விரிவாக: Igneous = magma/lava cooling; granite (slow, large crystals) vs basalt (fast, fine). Sedimentary = sediments + pressure; limestone (cement), sandstone, coal, oil. Metamorphic = heat + pressure on existing; limestone→marble, sandstone→quartzite, coal→graphite, clay→slate. Rock cycle — interconvertible.
கனியம் — விரிவாக: Iron (China/Australia/Brazil/India), Copper (Chile/Peru), Bauxite (Australia/Guinea), Gold (China/Australia/Russia), Diamond (Russia/DRC/Botswana/Australia), Coal (China/India/USA), Oil (Saudi/USA/Russia), Graphite (China + SL highest purity), Sapphire (SL Ratnapura world-famous). Battery minerals (lithium-Chile/Australia/China, cobalt-DRC 70%) tech-critical.
காடு — விரிவாக: Tropical rainforest (Amazon 5.5M km² + Congo + SEA — biodiversity hotspot). Savanna (Africa Serengeti). Deciduous (Europe + E.USA + China — autumn). Coniferous/Taiga (Russia + Canada + Scandinavia — world's largest continuous forest). Tundra (Arctic + Antarctic — permafrost). Deforestation Amazon 10,000+ km²/yr, Indonesia palm oil expansion.
மண் profile — விரிவாக: 100-400 yrs/cm formation (slow renewable). O (recent dead leaves) → A (humus-rich topsoil, agricultural zone) → B (clay + iron oxides subsoil) → C (weathered rock) → R (bedrock). வகைகள்: Chernozem (Russia/Ukraine steppes — world's most fertile, wheat), Laterite (tropical SL/India — red), Regur (Deccan — black, cotton), Desert sandy, Tundra permafrost, Mountain lithosol, Alluvial (Ganges/Mahaweli — fertile rice/wheat).
நீர் — விரிவாக: 97.5% salt + 2.5% fresh (70% ice in Antarctic/Greenland; 29.3% groundwater; 0.7% surface usable). Water cycle 5-step driven by Sun. Uses Agri 70% + Ind 20% + Dom 10%. Scarcity: Cape Town 2018 \"Day Zero\", Chennai 2019, MENA chronic. Solutions: rainwater harvesting (Singapore NEWater), drip irrigation (Israel), desalination (UAE).
Fossil fuels — விரிவாக: Coal 150 yrs + Oil 50 yrs + Gas 50 yrs reserves. Causes depletion: population, industrialization, transport, petrochemicals. Effects: climate change (75%+ CO₂), air pollution (7M deaths/yr WHO), geopolitics (Russia-Ukraine 2022 oil $130/barrel). Alternatives: Solar (China #1), Wind (China #1), Hydro (China Three Gorges 22 GW), Geothermal (Iceland 30%), Nuclear (France 70%), Biomass, Tidal, Green Hydrogen.
3R — விரிவாக: Reduce (highest priority — consume less) > Reuse (existing items again) > Recycle (process into new — energy-intensive). Sweden 99% waste recycled/energy-recovered. Germany Pfand bottle deposit 98% return. Japan strict sorting.
Sustainable Development — விரிவாக: Brundtland 1987 \"Our Common Future\". 3 pillars: Economic + Social + Environmental. SDGs 2015-2030 (17 goals). SDG 6 Water, 7 Energy, 12 Consumption, 13 Climate, 14 Marine, 15 Land. Examples: Costa Rica 99% renewable, Bhutan carbon-negative, Norway 80%+ EV.
Paris Agreement — விரிவாக: 2015 COP21. Limit warming to 1.5°C; NDCs every 5 yrs; $100B climate finance; net-zero 2050 developed / 2060-70 developing. 196 parties. Current trajectory ~2.5-2.8°C → insufficient. COP28 (2023 Dubai) — \"transition away from fossil fuels\" first time. Other treaties: Kyoto 1997, CITES 1973 (wildlife), Ramsar 1971 (wetlands — SL 6 sites), Montreal 1987 (ozone — recovering).

அலகு 2 — இலங்கையின் இயற்கை வளங்கள்

NEXT-LEVEL Numbers: Mahaweli 335km · Kelani 145km · Parakrama Samudra 2500ha · Wilpattu 131,693ha · Bogala graphite shaft 560m · Cat's Eye SL #1 · Norochcholai 900MW (3×300) · Victoria 210MW · Mannar 100MW + 250+ expansion · Soorya Bala Sangramaya 700MW solar · Total hydro ~1700MW.
Monsoons - விரிவாக: SW (Yala) — May-Sep — wet zone + SW coast; gives wet zone its 5000+ mm. NE (Maha) — Oct-Feb — dry zone + NE; gives dry zone its main rain. Inter-monsoon (Mar-Apr, Oct) — convectional rain.
Ancient Tanks - விரிவாக: Vasabha (67-111 AD), Mahasen, Dhatusena 5th c. (Kala Wewa), Parakramabahu I 12th c. (Parakrama Samudra "Sea of Parakrama"). Tank cascade system in dry zone catchments. Modern: Senanayake Samudra (D.S. Senanayake era, Gal Oya, 1950s).
UNESCO Heritage - விரிவாக: Sinharaja (1988) — 11,187 ha lowland rainforest, 60% endemic plants; Kudawa entry. Central Highlands (2010) — Horton Plains (Pidurutalagala 2524m, World's End), Knuckles ("Dumbara"), Peak Wilderness (Adams Peak/Sri Pada catchment). Cultural UNESCO: Anuradhapura, Polonnaruwa, Sigiriya, Dambulla, Kandy, Galle Fort.
Major National Parks - விரிவாக: Yala (Block 1-5; leopard density highest world; 977 km²), Wilpattu (131,693 ha "land of lakes"; largest area), Wasgomuwa, Horton Plains (UNESCO; 3160ha cloud forest+grassland), Bundala (Ramsar; flamingos), Udawalawe (308km²; 400+ elephants; Elephant Transit Home), Kumana (Yala East; birds), Minneriya (88km²; "gathering" 200-300 elephants Aug-Sep tank reservoir), Gal Oya (Senanayake Samudra; largest reservoir), Maduru Oya.
Graphite - விரிவாக: Vein graphite forms in hydrothermal cracks; SL geological uniqueness. Bogala (Aruggammana, Kegalle; 560m deep; since 1880s); Kahatagaha-Kolongaha (state mine); Ragedara. SL ~1% world quantity but ~near-monopoly of pure vein. Lithium-ion battery anode demand booming.
Gems - விரிவாக: Ratnapura (Sabaragamuwa); Elahera (Matale); Okkampitiya (Monaragala); Pelmadulla. Blue sapphire "Ceylon Sapphire" (Princess Diana/Kate Middleton ring 12 carat; Logan Sapphire 423 ct), Star Sapphire (Star of India 563 ct in American Museum of Natural History), Cat's Eye Chrysoberyl (SL world #1), Alexandrite, Star Ruby, Padparadscha (rare pink-orange). NGJA regulates; export ~$150-300M/yr.
Mineral Sands - விரிவாக: Pulmoddai (Trincomalee NE coast); LMSL operates. Ilmenite (FeTiO₃ → TiO₂ paint pigment), Rutile (TiO₂ premium — aircraft/surgical), Zircon (ZrSiO₄ — ceramics/nuclear), Monazite (REE + thorium), Garnet (abrasives), Sillimanite. ~70,000 tons/yr export to China/Japan/USA.
Cement Limestone: Aruwakkalu Puttalam — Holcim Lanka/INSEE; biggest plant. KKS Jaffna (historic). Eppawala. Cement + clinker partial self-sufficiency.
Mahaweli Hydropower - விரிவாக: Victoria 210MW (UK 1985), Kotmale 201MW, Randenigala 126MW, Rantembe 51MW, Ulhitiya-Rathkinda, Bowatenna, Polgolla. + Laxapana (Castlereagh-Maussakelle): New Laxapana 100MW, Wimalasurendra 50, Old Laxapana 50, Polpitiya 75. + Samanalawewa 120, Kukule 70. Total ~1700MW.
Coal + Oil: Norochcholai/Lakvijaya 900MW (CMEC China $1.35B; commissioned 2011-14; ~35% national electricity). Sapugaskanda Refinery (CPC 1969 Iranian tech; 50,000 bpsd). Kelanitissa CCGT 330MW. 100% coal+oil imported.
Renewables - விரிவாக: Mannar Wind (Adani/CEB JV 100MW 2024; expansion 250+); Hambantota Welikanda Solar 100MW; Soorya Bala Sangramaya rooftop ~700MW; biomass (rice husk, dendro Gliricidia); geothermal nil. 2030 target 70% RE.
Mahaweli Programme - விரிவாக: 1968 master plan; 1977 Accelerated MDP under JR Jayewardene; UK/Germany/Sweden/Japan/WB/ADB aid. 5 dams Polgolla→Kotmale→Victoria→Randenigala→Rantembe. Hydro 700MW + irrigation 365,000ha + resettlement 1M+. New towns Dehiattakandiya, Girandurukotte. MASL manages. Controversies: deforestation, displacement, ethnic tension.

அலகு 3 — உலக சனத்தொகை

3 phases of history: Hunter-gatherer (~5M, 10kyr+) · Agricultural (1B by 1800) · Industrial explosion (8B by 2024).
Demographic Transition Model (5 stages): Stage 1 high B+D (pre-industrial); Stage 2 D↓ first (rapid growth, today Africa); Stage 3 B↓ (India today); Stage 4 low B+D stable (USA/China today); Stage 5 B<D declining (Japan/Italy/Korea).
Growth causes: Medical (vaccines, antibiotics, sanitation), Agricultural (Green Revolution Borlaug 1960s, fertilizers, IR8 rice), Industrial (income+housing).
Physical factors - விரிவாக: Climate (moderate temperate+tropical wet preferred); Terrain (flat valleys); Soil (alluvial fertile — Ganges/Nile/Yangtze); Water (rivers, lakes); Resources (coal/oil); Coast access.
Human factors - விரிவாக: Industry (Manchester/Shenzhen); Transport hubs; Urbanization (Tokyo/Mumbai/Lagos megacities); Agricultural intensity (Asia rice); History (Beijing/Cairo); Politics (Brasilia, China east coast); War displacement (Syria/Yemen).
Egypt example: 95% of 105M on 5% land (Nile valley + delta). Water+soil determines.
Challenges: Food (700M undernourished), Water (2B water-stressed), Energy (climate), Urban (mega-slums), Unemployment (Africa youth bulge), Environment (deforestation+pollution), Healthcare (1B no access), Education (250M out-of-school), Resource conflicts, Climate migration.
China One-Child Policy 1979-2015: Prevented ~400M births; side effects: gender imbalance + aging crisis. Now 3-child policy (2021).
India NPP: 1976 controversial sterilizations; 2000 rights-based; fertility 5.9 (1950) → 2.0 (2020). Kerala model: literacy → low fertility.
Solutions: Female education (most effective), contraception access, social development, voluntary family planning, ICPD Cairo 1994 rights-based.
Pro-natalist (declining countries): Hungary/Korea cash incentives, Sweden/France childcare, immigration (Canada/Germany).
SL position: Stage 3-4 transitional. BR 15 · DR 7 · NI 0.5% · fertility 2.0 · life expectancy 77. Aging emerging.

அலகு 4 — இலங்கையின் சனத்தொகை

Census history: 1871(2.4M) → 1901(3.6) → 1946(6.7) → 1953(8.1) → 1971(12.7) → 1981(14.8) → 2001(18.7) → 2012(20.3) → 2024(~22M est).
1953 peak causes: Malaria eradication (DDT 1947-49 WHO+Rockefeller), antibiotics, vaccines, maternal+child health. DR 22→10/1000; BR stayed 37; NI 2.8%/yr = doubling 25 yrs.
Decline (1953→2012, 2.8%→0.7%): Female literacy ~93% (S Asia highest); FHB 1965 + FPA 1953; voluntary contraception; marriage age 18→25+; urbanization; war emigration; TFR 5.5→2.0.
Provincial concentration: Western 30% pop on 6% land. Northern 5% (lowest, post-war).
Districts (high pop): Colombo 2.3M · Gampaha · Kurunegala · Galle. Low pop: Mullaitivu, Mannar, Vavuniya.
Ethnic distinction: SL Tamils = N/E ancient (thousand+ yrs); Indian Tamils = 19th c British plantation labour upcountry estates; SL Moors = Arab+local descent, Tamil-speaking but distinct census ethnicity.
Religion-ethnicity correlation: Sinhala≈Buddhist (some Christians); Tamil≈Hindu (some Catholic); Moor=Muslim.
Internal migration: Rural→Urban (Colombo magnet). FTZ female workers Katunayake/Biyagama/Koggala. Mahaweli planned wet→dry.
External: Middle East 1.5M-2M (Saudi/UAE/Kuwait/Qatar) ~60% female housemaids. Tamil diaspora Canada/UK/Australia/EU 1M+. Post-2022 crisis: 300K+ skilled emigrated Australia/Canada.
Remittances: $5-7B/yr top FX source (often > apparel).
Aging: 60+ 12.2(2012)→16(2024)→25(2040)→30(2050)%. EPF/ETF reform, healthcare, elderly care, retirement age challenges.
Urban congestion: Colombo PM2.5 5xWHO; traffic 2h commute; housing crisis; Meethotamulla collapse 2017; LRT cancelled 2019.
Regional imbalance: Western GDP 50%; N/E recovery; hill country decline. Solutions: decentralize, second-tier cities, provincial autonomy 13A.
Female migration impact: "Middle East orphans"; marital strain; worker abuse; Rizana Nafeek 2013 execution. Solutions: skilled migration, worker protection, family welfare.

அலகு 5 — அபிவிருத்தி

HDI 3 dimensions - detailed: Health = Life Expectancy at Birth. Knowledge = Expected Years + Mean Years of Schooling. Living = GNI per capita PPP. Geometric mean of 3 → composite. Switzerland #1 (0.967); SL #78 (0.78 High); Chad/Niger/S.Sudan lowest (<0.45).
PQLI - detailed: Morris David Morris 1979 (Overseas Development Council). 3 equal-weight indicators: IMR + Life expectancy at age 1 + Literacy. Scale 0-100. Kerala 1981 = 82 PQLI despite low GDP — proved social development possible.
WB Income Classification (2024 thresholds): High >$13,845 · Upper-middle $4,466-13,845 · Lower-middle $1,136-4,465 · Low <$1,135. SL = lower-middle (~$3,800).
MDGs 2000-2015 (8 goals): 1.Poverty 2.Education 3.Gender 4.Child mortality 5.Maternal health 6.HIV/malaria 7.Environment 8.Partnership. Halved extreme poverty.
SDGs 17 goals (memorize key ones): 1=Poverty · 2=Hunger · 3=Health · 4=Education · 5=Gender · 6=Water · 7=Energy · 11=Cities · 13=Climate · 14=Marine · 15=Land · 16=Justice · 17=Partnerships.
Sen Capability Approach: Development = expanding people's freedoms to choose lives they value. Functionings (what we do) + Capabilities (what we can do). Famine = entitlement failure, not just food shortage.
Economic indicators detail: GDP (domestic output); GNI = GDP + foreign income; PPP-adjusted = comparable across countries; growth rate annual %; per capita = GDP/pop; Gini = inequality (0-1).
Social indicators detail: Life expectancy (Japan 84 → Sierra Leone 55); IMR/1000 (Finland 2 → Sierra Leone 80); Literacy (Norway 100% → Niger 35%); GDI/GII = gender; MMR = maternal mortality; tertiary enrolment.
Env indicators detail: CO₂/capita (Qatar 37→USA 14→India 1.9→Burundi 0.2); Forest % (Bhutan 71→SL 29→Bangladesh 11); EPI Yale+Columbia annual; Ecological Footprint Global Footprint Network; renewable energy %.
Composite indices: HDI (UNDP 1990); PQLI (Morris 1979); IHDI (inequality-adjusted HDI); MPI (Multidimensional Poverty Index — UN); HPI (Happy Planet Index); Bhutan GNH (Gross National Happiness).
Country sustainability leaders: Costa Rica 99% renewable. Bhutan carbon-negative + GNH framework. Denmark wind 50%+. Norway EVs 80%+. Iceland 85% renewable + geothermal heating. Sweden net-zero law. Rwanda plastic bag ban + ICT leapfrog. Singapore Green Plan 2030.
Intermediate categories: NICs/Asian Tigers (S.Korea/Taiwan/Singapore/HK); BRICS+ (Brazil/Russia/India/China/SA/UAE/Iran/Egypt/Ethiopia); Tiger Cubs (Malaysia/Thailand/Philippines/Indonesia); LDCs 46 countries; Petro-states; Conflict states.

அலகு 6 — உலகில் இயற்கை இடர்கள்

Plate boundaries detail: Convergent (collision, Indo-Aus under Eurasian = Himalayas + Nepal 2015); Divergent (Mid-Atlantic Ridge, East African Rift); Transform (San Andreas California, 1906 SF + 1989 Loma Prieta).
Earthquake scales: Richter/Moment Magnitude (energy, logarithmic — M6→M7 = 32× energy); Mercalli Intensity (I-XII observed damage). Seismograph records.
Major earthquakes: 2010 Haiti M7.0 (230K dead — poor construction). 2011 Tohoku M9.1 (Fukushima). 2015 Nepal Gorkha M7.8 (9K). 2023 Turkey-Syria M7.8 (60K+).
Volcano examples: 79 AD Vesuvius (Pompeii). 1883 Krakatoa (36K + global cooling). 1980 Mt St Helens (57). 1991 Pinatubo (cooling 0.5°C 2 yrs). 2022 Hunga Tonga (largest atmospheric blast since Krakatoa).
Volcano types: Active (Etna, Kilauea); Dormant (Fuji 1707 last); Extinct (Kilimanjaro).
Tsunami detail: Speed = jet plane in deep ocean (700-800 km/h). First wave NOT always largest — "wave train." 2004 NO Indian Ocean warning; 2006 IOTWS established. DART buoys + sirens.
2004 Tsunami detail: Indo-Australian subducted Burma microplate, 600+km rupture, 8-10 min duration. SL Peraliya train disaster ~1,700 dead (deadliest train disaster ever). $13B+ global aid. SL Disaster Management Centre established 2005.
Cyclone formation: SST 26.5°C+ to 50m depth, lat 5-20° Coriolis needed, low wind shear, pre-existing disturbance, moisture, instability. No cyclones South Atlantic or SE Pacific (cold currents).
Cyclone structure: Calm "eye" (15-65km) — descending air. "Eye wall" surrounding — strongest winds + rain. Spiral rainbands (100-500km out). Storm surge = often deadliest aspect.
Cyclone seasons: NW Pacific year-round peak Jul-Oct (~25/yr); N Atlantic Jun-Nov peak Aug-Oct (~14/yr); Bay of Bengal Oct-Nov+Apr-May (~5/yr but deadliest); Arabian Sea Apr-Jun+Oct-Dec; SW Indian Ocean Nov-Apr.
Deadly cyclones: 1970 Bhola Bangladesh 300-500K (deadliest ever); 1991 BD 138K; 2008 Nargis Myanmar 138K; 2005 Katrina USA 1,800 ($125B); 2013 Haiyan Philippines Cat 5 315 km/h 6,300 dead; 2017 Maria Puerto Rico ~3,000; 2020 Amphan Bay of Bengal during COVID.
Floods major: 1931 Yangtze 4M (deadliest disaster ever). 1998 Yangtze 3,000+ 15M displaced. 2010 Pakistan Indus 20M affected. 2017 Houston Harvey record rain. 2022 Pakistan 1/3 country submerged.
Drought types: Meteorological (rain deficit), Hydrological (water bodies low), Agricultural (soil moisture insufficient), Socioeconomic (demand > supply).
Major droughts: 1930s Dust Bowl USA (2.5M displaced). 1968-85 Sahel sub-Saharan (millions dead). 1984-85 Ethiopia (1M dead, Live Aid 1985). 2018 Cape Town "Day Zero" (first major city near cutoff). 2022 Europe Rhine/Po/Loire historic lows.
Wildfires + Landslides: 2019-20 Australia "Black Summer" 18M ha 3B animals. 2018 Camp Fire California 85 dead Paradise destroyed. 2023 Canada record 18M ha. 1970 Peru Mt Huascarán landslide 22K dead.
Sendai Framework 2015-2030 priorities: (1) Understanding risk (mapping/assessment), (2) Strengthening governance (laws/institutions), (3) Investing in resilience (infrastructure/ecosystems/safety nets), (4) Enhancing preparedness (warning/evacuation/training).

அலகு 7 — இலங்கையில் இயற்கை இடர்கள்

Major flood events: 1957 Mahaweli; 2003 May (260+ dead — Ratnapura/Galle/Kalutara); 2010-11 Eastern (1M+ displaced); 2014 N+E; 2016 May Roanu (100+); 2017 May (200+ Bulathkohupitiya); 2024 multi-region.
Landslide chronology: 1957 Helauda (12); 1986 Walapane (122); 1989 Padiyapelella (36); 2003 Kelani valley; 2014 Meeriyabedda (38 — Indian-origin estate housing); 2016 Aranayake (127 deadliest); 2017 Bulathkohupitiya (200+ multi-event); 2024 Bandarawela/Hatton.
Landslide causes: steep slopes 15-30°+, heavy rain 300+mm/24h trigger, weak regolith (laterite), deforestation (tea/vegetable), slope cutting (roads), historical recurrence.
Drought details: Dry zone <1250 mm; depends on NE monsoon Oct-Feb. Recurring years: 1976-77, 1986-87, 1996-97, 2001-02, 2016-17 (2M affected, Rs 30B losses), 2024.
Drought impacts: Paddy yield loss; food insecurity; drinking water; hydropower drop; CKDu link (agro-chemical + fluoride water hypothesis in NCP/Uva).
Cyclone history: 1907 Mannar; 1922 north; 1964 Dec Batticaloa; 1978 Nov Batticaloa+Trincomalee 700+ dead 1M displaced (deadliest); 1992 Eastern; 2000 north; 2016 Roanu (Sabaragamuwa+Western); 2018 Sagar; 2024 Remal outer.
Tsunami 2004 SL detail: Worst hit Eastern Province (Trincomalee/Batticaloa/Ampara), Southern (Hambantota/Matara/Galle), SW (Beruwala/Hikkaduwa). Peraliya \"Queen of Sea\" train ~1,700 dead Telwatta. Yala wildlife mostly survived (fled inland). 800K displaced into camps.
2004 aftermath: DMA 2005 + DMC; NBRO expanded; IOTWS 2006; CCD coastal setbacks 100-300m; \"Build Back Better\"; mangrove restoration; ~$2-3B aid; 5-7yr recovery.
Coastal erosion: SW coast (Beruwala-Galle) worst — SW monsoon waves + sand mining + coral mining + harbour breakwaters. CCD setbacks + groynes + revetments. Mangrove restoration.
Lightning detail: Tropical convective storms + high CAPE + humidity + inter-monsoon Mar-Apr+Oct peak + rural paddy field exposure + tree-shelter myth. Met Dept warnings; public education.
DMC + institutions: NCDM (President-chaired policy); DMC operational coordination under MOD; NBRO landslides; Met Dept weather; Irrigation Dept floods; CCD coastal; CEA env; NARA marine; GSMB seismic; Tri-Services emergency; SL Red Cross + NGOs + UN.
Sub-national: 25 District Disaster Management Committees + Divisional + GN level grassroots.
Sendai 4 priorities applied to SL: (1) Understanding risk — NBRO maps + climate projections. (2) Strengthening governance — DMC + sub-national. (3) Investing in resilience — infrastructure + ecosystems + social protection. (4) Enhancing preparedness — EWS + evacuation + drills.
NNDIS detail: Launched 2016 post-flood/landslide gaps. SLIC administers. Household Rs 2.5M + SME Rs 2M coverage. Government premium for poor. Triggered by floods/landslides/cyclones/droughts/lightning/fires.

அலகு 8 — காலநிலை மாற்றங்கள்

Greenhouse Effect mechanism: Sun emits shortwave (UV+visible) reaching Earth → Earth re-emits as infrared longwave → GHGs absorb + re-radiate downward → atmosphere warm.
GHGs detailed: CO₂ from fossil fuels + deforestation + cement (75%, lifetime 100-1000yrs). CH₄ methane from cattle + rice + landfills + gas leaks (84× GWP, 12yr). N₂O from fertilizers + soil + industry (273× GWP, 114yr). F-gases (HFC/PFC/SF₆) from refrigeration + electronics (1000-23000× GWP).
Energy sector breakdown: Electricity+heat generation (coal/gas/oil); Transport (cars/aviation/shipping 20%); Industry (steel/cement/chemicals); Buildings (heating/AC).
Agriculture sector: Livestock alone 14% global GHG. Rice paddies anaerobic methane. Fertilizers N₂O. Deforestation (Amazon/Congo/Indonesia) releases stored carbon.
Cumulative emitters (1850-2023): USA 25% (historical leader), EU 17%, China 14%, Russia 7%, Africa 3% (lowest historically).
Cryosphere effects: Arctic sea ice -13%/decade; could vanish summer 2050. Greenland 280 billion tons/yr loss. Antarctica accelerating. Mountain glaciers retreating worldwide. Permafrost thawing = methane release positive feedback.
Sea level: +25cm since 1900; +30-100cm projected by 2100. Coastal cities (Mumbai, Jakarta, Shanghai, Colombo, NYC, Miami) threatened. Small islands (Maldives 2m max, Tuvalu, Marshall) existential.
Extreme weather: Heatwaves (Europe 2003 70K dead, India 2024 49°C); cyclones (Cat 4-5 fraction rising; rapid intensification); rainfall +7% per °C; floods (2022 Pakistan 1/3 submerged, 2023 Libya Derna 11K); droughts (Cape Town 2018, California, Horn of Africa); wildfires (Australia 2019-20 18M ha 3B animals, California, Canada 2023).
Ocean impacts: 90% excess heat absorbed; acidification pH -0.1; coral bleaching mass events (2016, 2017, 2020, 2024); deoxygenation; marine heatwaves.
Ecological: Species range shifts (polar disappearing, tropical expanding); phenology disruption (flowers earlier, bird migration mismatch); mass extinction acceleration; coral 70-90% loss at 1.5°C; insect collapse.
Human impacts: Climate migration 100M+ by 2050 (World Bank Groundswell); dengue/malaria range expansion; heat-related deaths; water stress 2B+; conflicts (Syria drought, Darfur, Sahel).
Treaty chronology: 1987 Montreal (CFC), 1988 IPCC, 1992 UNFCCC (Rio), 1997 Kyoto (developed binding), 2015 Paris (universal voluntary). COP26 Glasgow 2021 coal phase-down. COP27 Sharm 2022 Loss & Damage fund. COP28 Dubai 2023 first \"transition away from fossil fuels.\" COP29 Baku 2024 $300B/yr finance.
Paris mechanisms: NDC every 5 years progressive; transparency framework; $100B/yr finance (largely unmet); ~140 countries pledged net-zero; current trajectory ~2.5-2.8°C (insufficient).
SL specific impacts: Sea level (Colombo/Galle/Jaffna); monsoon variability (2016-17 drought then 2017 flood); tea industry decline (optimal 15-27°C stressed); paddy yield decline 5-15%; coral bleaching Hikkaduwa/Pigeon Island/Bar Reef; cyclone intensification Bay of Bengal; landslides + droughts both intensifying; dengue range expansion.
SL initiatives: Soorya Bala Sangramaya rooftop solar 700MW; Mannar wind 100MW+expansion; mangrove restoration; drought-tolerant paddy BG/AT; EV policy emerging; Hambantota wind+solar zones; GCF projects.

அலகு 9 — 1:50,000 இலங்கையின் இடவிளக்கப் படங்கள்

Sheet basics detailed: SL Survey Department prepares. Each sheet covers 5'×5' (latitude × longitude minutes) graticule. Total 92 sheets cover Sri Lanka. Index sheet shows all 92.
Scale relationships: 1:50,000 = 1 cm map represents 50,000 cm ground = 500 m = 0.5 km. So 2 cm = 1 km. Area: 1 cm² = 0.25 km² (linear ratio squared!). 1 km² area = 4 cm² on map.
Grid system fully: Vertical north-south lines = Eastings. Horizontal east-west lines = Northings. Lines spaced 2 cm = 1 km apart. 4-fig reference identifies 1×1 km square using west + south edge values. 6-fig reference adds tenths within square — east-tenth + north-tenth — gives ~100 m × 100 m precision.
Contour rules detailed: Equal-elevation curves. SL maps brown color. CI 10 or 20m typical. Index contour every 5th (e.g., if CI=10m, index every 50m) — thicker, labeled. Spacing = slope (close=steep, spaced=gentle). Direction matters: V opening UP toward higher contour = ridge; V opening DOWN toward lower contour = valley. Concentric closed loops = peak (innermost highest); closed loops with hachures = depression (innermost lowest).
10 landform types to identify: Peak (concentric); Plateau (closed wide); Plain (no/wide contours); Ridge (V up-slope); Valley (V down-slope); Slope (parallel); Cliff (touching contours); Waterfall (contours crossing stream); Depression (closed with hachures); Isolated hill (lone peak surrounded by lowland).
8 drainage patterns: Dendritic (tree, soft rock, SL Mahaweli/Kelani/Kalu); Trellis (perpendicular, folded sedimentary); Rectangular (right angles, jointed/faulted); Radial (outward, volcanic cones); Centripetal (inward, basins); Parallel (slope-controlled); Annular (rings, eroded domes); Deranged (chaotic, glaciated).
River features: Source, confluence, tributary, distributary, meander (mature river loops), oxbow lake (cut-off meander), braided river (multiple channels), delta (river splits at mouth), waterfall, rapids, estuary.
Coastal features: Headland/cape (projection); Bay (sea curve into land); Lagoon (partially enclosed coastal water — Negombo, Madu Ganga); Estuary (river mouth + tidal); Delta (river-built fan); Spit/sandbar (narrow projection); Island; Peninsula (Jaffna); Reef (submerged ridge); Beach.
Settlement types: Dispersed (isolated houses spread — rural agri); Nucleated (clustered around center — village/town); Linear (along road/river/coast); Compact urban (dense built-up shading).
Transport hierarchy: A class solid double red (e.g. A1 Colombo-Kandy); B class solid single red; C/D dashed red; footpath/cart track dashed black or yellow; railway solid black with ties.
Religious + civic symbols: Buddhist stupa/dagoba; Hindu kovil tower; Mosque crescent; Church cross; School building; Hospital red cross; Police P; Post Office PO; Trig point ▲.
Administrative boundaries: District (thick red dashed); DS Division (medium); GN Division (thin); National park (green dashed); Forest reserve (green solid).
Land use: Paddy green block (often terraced in hills); Tea estate yellow w/ notation; Coconut yellow w/ palm dots; Rubber yellow w/ notation; Forest light green shading; Scrub jungle green dotted; Mining black hatched.
Distance methods: Straight ruler × 0.5 km/cm. Curving = thread/string method (lay along curves, measure straightened). Or compass small steps.
Area methods: Rectangular = length × breadth × 0.25 km²/cm². Irregular = square count (full + half squares; full square = 1 km², half = 0.5 km²).
Gradient calc: Rise (vertical) ÷ Run (horizontal). Convert to same units. e.g., 600m rise over 3000m = 1:5 = 20%. Classifications: 1:5+ very steep; 1:10 steep; 1:20 moderate; 1:50 gentle; 1:100 nearly flat.
Cross-section drawing: Choose A-B line. Mark each contour intersection along strip of paper. Plot on graph paper: horizontal = distance (map scale); vertical = elevation. Use ~10× vertical exaggeration. Connect smoothly. Label peaks + valleys + rivers.

அலகு 10 — தரவுகளை விளக்குவதற்காக வரைபுகளைப் பயன்படுத்தல்

Decision tree: Time-series = line. Discrete category compare = bar. Proportion/composition = pie. Climate = climograph. Correlation 2 variables = scatter. Frequency distribution = histogram. Spatial = choropleth/cartogram. Demographic structure = population pyramid.
Line graph detail: X=independent (usually time). Y=dependent. Uniform scale both axes. Connect points smoothly. Multiple lines = legend. Compound = filled areas. Cumulative = running total.
Bar chart detail: Equal-width bars + equal gaps. Height = value. Best ordered by value descending. Variations: Simple (1 var per cat), Multiple (groups), Stacked (total + sub), 100% stacked (proportional composition), Horizontal (long names), Population pyramid (age-sex).
Pie chart detail: Calculate each angle = (value/total) × 360°. Draw circle. Mark angles from 12 o'clock clockwise. Largest slice first. Color/shade differently. Label name + % on each. Title + source. Verify sum = 360°.
Pie angle examples: 25%→90°; 50%→180°; 75%→270°; 100%→360°. Each 1% = 3.6°.
Climograph detail: X=12 months. Left Y=temp (°C). Right Y=rainfall (mm). Temperature plotted as line. Rainfall plotted as bars. Annual range = max-min temp. Annual total = sum monthly rainfall.
Climate zone patterns: Equatorial = stable hot + heavy rain year-round. Tropical wet-dry/savanna = hot + distinct wet/dry. Monsoon = bimodal rain. Mediterranean = mild winter wet + hot summer dry. Temperate = moderate variable. Continental = wide T range. Polar = cold + dry. Mountain = cool + variable.
SL climographs: Colombo wet zone (stable 27°C, dual rain peaks May-Sep + Oct-Dec, ~2400mm). Nuwara Eliya highland (13-16°C, SW monsoon peak May-Sep, 1900mm). Anuradhapura dry zone (24-31°C, Oct-Dec rain ~1300mm). Hambantota (26-30°C, Oct-Dec only ~1000mm).
Scatter detail: Each (x,y) point. Trend line optional. Reveals: Positive correlation (rise together); Negative (opposite); None; Outliers.
Histogram detail: Continuous data binned. Bars TOUCH (no gaps). Y=frequency. Shape reveals: Normal (bell), Skewed, Bimodal, Uniform.
Choropleth detail: Map of regions; each shaded by data value. Choose 4-7 color classes. Use sequential color (light to dark). Always include legend showing class ranges. e.g., SL population density by district.
Cartogram detail: Geographic distortion. Country/district size proportional to data (e.g., population, GDP). Reveals data magnitude vs geographic size.
Pictograph detail: Choose icon + unit value (1 icon = 1M people). Repeat icons proportionally. Good for general audience but imprecise.
Population pyramid detail: Horizontal back-to-back bars. Left = males; Right = females. Each row = age cohort. Shape reveals demographic stage: Broad-base = stage 2-3 (young growing); Rectangular = stage 4 (stable); Inverted = stage 5 (aging declining).
Common errors: Pie for time-series; Bar for proportions; Climograph axes reversed; 3D effects distort; Truncated Y-axis exaggerates; Wrong angle formula; Missing legend for multiple series; Too many pie categories; Missing source.

அலகு 1 — புவியின் இயற்கை வளங்கள்

அலகின் வரிசை: Resource definition → 2 types (renewable/non-renewable) → 3 rock types → minerals (metallic + non-metallic) → 5 forest zones → soil (formation + profile + types) → water (distribution + cycle + uses + scarcity) → conservation (3R + SD + Paris).
மறக்காத %: நீர் 97.5% salt + 2.5% fresh (70% ice; 0.7% usable). Use: Agri 70% / Ind 20% / Dom 10%. China iron 50% world, Saudi+UAE+Russia oil exporters. Fossil fuels = 75% global CO₂.
மறக்காத பெயர்கள் + ஆண்டுகள்: Brundtland 1987 (sustainable dev) · Paris 2015 (1.5°C) · Kyoto 1997 · CITES 1973 · Ramsar 1971 (SL has 6 sites) · Montreal 1987 (ozone). SDG 2015-2030.
SL-specific: Graphite Bogala/Kahatagaha/Ragedara — world's highest purity (vein 95%+). Blue sapphire Ratnapura world #1. 6 Ramsar wetlands (Bundala, Anavilundawa, Madu Ganga, Vankalai, Wilpattu, Annaiwilundawa). Mahaweli alluvium fertile rice belt.
எளிதில் தவறும் ஜோடிகள்: (1) Resource = Nature + Utility (இரண்டுமே). (2) Coal/oil = sedimentary, NOT igneous. (3) Marble = metamorphic (limestone transformed). (4) Amazon = rainforest; Taiga = coniferous. (5) A = topsoil (most fertile), B = subsoil. (6) நீர் 2.5% fresh BUT 0.7% usable. (7) Bauxite → aluminium (NOT iron). (8) 3R order: Reduce > Reuse > Recycle (NOT alphabetical).
கட்டுரைக்குத் தயார்: (1) Resource definition + renewable vs non-renewable. (2) 3 rock types + examples. (3) World minerals (metallic + non-metallic). (4) 5 forest zones + importance. (5) Water cycle + distribution + uses + scarcity + solutions. (6) Soil formation + 5-horizon profile + types. (7) Fossil fuels depleting + alternatives. (8) Sustainable Development + 3R + Paris Agreement.
புதிய போக்குகள்: Solar electricity cheapest globally. EV revolution (Norway 80%, China #1 producer). Green hydrogen for shipping/steel. Circular economy. Carbon capture. Geothermal expansion. Battery minerals geopolitics. Climate finance ($100B/yr commitment, often unmet).

அலகு 2 — இலங்கையின் இயற்கை வளங்கள்

அலகின் வரிசை: Water (rain+rivers+tanks) → Forests (29%+ UNESCO Sinharaja/Central Highlands) → Soils (RBE/RYP/Alluvial) → Minerals (Graphite/Gems/Sands/Limestone) → Maritime (EEZ 517,000 km²) → Energy (mix 35-30-20-15) → Conservation challenges.
எளிதில் தவறும் ஜோடிகள்: (1) Mahaweli 335 km longest. (2) Parakrama Samudra (Polonnaruwa) ancient vs Senanayake Samudra (Gal Oya) modern. (3) Sinharaja 1988 + Central Highlands 2010 = UNESCO Natural. (4) Yala = leopards; Wilpattu = area; Udawalawe = elephants; Minneriya = Gathering. (5) Graphite அளவில் சிறு (~1%) ஆனால் தரத்தில் #1. (6) Ratnapura = gems (NOT Anuradhapura ancient capital). (7) Bogala = Kegalle (NOT Anuradhapura). (8) Norochcholai = coal; Sapugaskanda = refining. (9) Eppawala = phosphate (NOT limestone). (10) EEZ 517,000 km² = 7× nation; Coast 1,340 km.
Princess Diana ring = Ceylon Blue Sapphire (12-carat). Now Kate Middleton/Catherine Princess of Wales. SL gem advertising.
2030 RE target = 70%. Currently ~45-50%. Massive solar + wind + grid expansion needed.
CKDu = dry zone (Anuradhapura/Polonnaruwa/Mahiyangana) chronic kidney disease; agro-chemical/fluoride water suspect; 100,000+ affected.
கட்டுரைக்குத் தயார்: (1) Water vs rain+rivers+tanks. (2) Forests + UNESCO. (3) Mineral vs Graphite+Gems+Sands+Limestone. (4) Energy + 2030 RE target. (5) Mahaweli Development Programme. (6) Sinharaja. (7) EEZ + UNCLOS. (8) Pollution + conservation institutions.

அலகு 3 — உலக சனத்தொகை

நினைவு டார்கெட்: 2024 = 8B. Asia 60%. China+India 37%. J-curve.
1→2B = 130 yrs; recent 12-13 yrs each billion.
Demographic transition 5 stages: high B/D → D drops → B drops → low B/D stable → declining.
Examples by stage: Stage 2 = Niger/DRC/Africa; Stage 3 = India/Bangladesh/Mexico; Stage 4 = USA/UK/France/China; Stage 5 = Japan/Italy/Korea/Russia.
3 dense + 3 sparse: dense=S/E Asia + W/C Europe + NE US; sparse=deserts + polar + mountains/rainforests.
Top 6 countries (2024): India 1.43B · China 1.43B · USA 340M · Indonesia 280M · Pakistan 240M · Nigeria 230M (rapidly rising).
Country policies: China One-Child (1979) → 2-child (2016) → 3-child (2021); India NPP 1976+2000; Iran voluntary; Singapore reversed; Africa varied.
Key terms: Population vs Density · Growth rate · Fertility rate · Life expectancy · Demographic dividend · Aging society · Replacement fertility (2.1).
எளிதில் தவறும்: (1) growth ≠ density. (2) developing = high growth (not developed). (3) Asia 60% (not 50). (4) China 1st in 2014 textbook (reality India overtook 2023). (5) J-curve. (6) include both physical + human factors.
கட்டுரைக்குத் தயார்: (1) Historical growth + J-curve. (2) Distribution + factors. (3) Demographic transition stages. (4) Population explosion challenges + policies.

அலகு 4 — இலங்கையின் சனத்தொகை

Memorize numbers: 20.3M (2012) · density 323 · TFR 2.0 · 1871 first census · 1953 peak 2.8% · 2012 NI 0.7%. Colombo 2.3M (highest) + 3438/km² (highest density). Mullaitivu 92/km² (lowest).
2012 percentages: Sinhala 74.9 + Tamil 11.2 + Moor 9.2 + Indian Tamil 4.2; Buddhist 70.2 + Hindu 12.6 + Islam 9.7 + Christian 7.4; Rural 77.3 + Urban 18.2 + Estate 4.4; 0-14=25.6 + 15-59=62.2 + 60+=12.2; F 51.5 + M 48.5.
எளிதில் தவறும்: (1) SL Tamil vs Indian Tamil distinction. (2) Sinhala % ≠ Buddhist % (some Sinhalese Christian). (3) Sector "Estate" 4.4% (not "Plantation"). (4) 1953 peak caused by death rate fall NOT birth rate rise. (5) Push (away) vs Pull (toward).
Mahaweli moved ~1M people wet→dry zone; controversial Sinhalese resettlement in Tamil-majority East contributed to ethnic conflict.
Civil war 1983-2009 impact: ~75K deaths, 800K+ displaced, ~1M Tamil diaspora abroad, demographic disruption.
கட்டுரைக்குத் தயார்: (1) Growth history 1871-2012 + 1953 peak. (2) Distribution (provincial/district/ethnic/religion/age). (3) Internal+external migration. (4) Aging+urban+regional+female migration challenges + solutions.
Post-2022 brain drain = doctors, engineers, IT to Australia/Canada/EU. Major concern.
SL stage in demographic transition: Stage 3-4 transitional. Below replacement TFR. Aging like Thailand. Way ahead of Pakistan/Bangladesh (stage 2-3).

அலகு 5 — அபிவிருத்தி

Memorize: HDI=UNDP 1990. PQLI=Morris 1979. Brundtland 1987. MDGs 2000-2015 (8). SDGs 2015-2030 (17). SDG 13=Climate. Asian Tigers=4 NICs. LDC count=46.
SL position: GDP/capita ~$3,800 (lower-middle); HDI 0.78 High (#78); life exp 77; literacy 93%; IMR 6; population 22M; demographic stage 3-4.
எளிதில் தவறும்: (1) HDI 3 dimensions ≠ PQLI 3 indicators (different). (2) GNI = GDP + foreign income. (3) Sustainable = 3 pillars (not env only). (4) MDGs preceded SDGs (replaced, not in addition). (5) Sen capabilities approach.
Country examples to memorize: Switzerland HDI #1; Bhutan carbon-negative; Costa Rica renewable; Norway EV leader; S.Korea NIC; Bangladesh graduating LDC 2026.
கட்டுரைக்குத் தயார்: (1) Old vs new development concept + 3 indicator types. (2) Sustainable development + 3 pillars + SDGs. (3) Developed vs developing + intermediate categories + WB income tiers.
Modern shift: binary developed/developing dropped by WB since 2016 — uses income tiers + multi-dim indicators. Spectrum continuous not categorical.
Challenges to SDGs 2030: COVID setback, Ukraine war, climate crisis, financing $2.5-3T/yr gap, inequality rising, geopolitical fragmentation. UN says most goals off-track.
Emerging concepts: Green economy, Circular economy, ESG investing, Just transition, Doughnut economics (Kate Raworth), Net-zero 2050.

அலகு 6 — உலகில் இயற்கை இடர்கள்

Memorize: Pacific Ring of Fire 80% quakes + 75% volcanoes. 2004 Boxing Day = 14 countries 230K. 1970 Bhola = deadliest cyclone 300-500K. 1931 Yangtze = deadliest disaster 4M.
Cyclone formation: SST 26.5°C, lat 5-20° (NOT equator), low shear. Saffir-Simpson Cat 1-5. Cat 5 = 252 km/h.
Plate types 3: Convergent + Divergent + Transform.
Volcano states 3: Active + Dormant + Extinct.
Drought types 4: Meteorological + Hydrological + Agricultural + Socioeconomic.
Cyclone naming: Cyclone=Indian Ocean / Hurricane=Atlantic / Typhoon=NW Pacific. SL on cyclone path NOT typhoon.
Year-Hazard pairs: 79 AD Vesuvius, 1755 Lisbon, 1883 Krakatoa, 1931 Yangtze, 1970 Bhola, 1980 St Helens, 1991 Pinatubo, 2004 Indian Ocean Tsunami, 2005 Katrina, 2008 Nargis, 2010 Haiti, 2011 Tohoku, 2013 Haiyan, 2015 Nepal, 2017 Maria, 2018 Cape Town, 2019-20 Australia, 2022 Pakistan + Hunga Tonga, 2023 Turkey-Syria + Canada.
எளிதில் தவறும்: (1) Hazard ≠ Disaster. (2) Richter logarithmic NOT linear. (3) Cyclones NOT on equator (Coriolis). (4) First tsunami wave NOT always largest. (5) Active vs Dormant vs Extinct volcano. (6) Saffir-Simpson = cyclone scale; Richter = quake; VEI = volcano. (7) Drought = prolonged deficit (not just no rain today).
கட்டுரைக்குத் தயார்: (1) Hazard vs disaster + 4 main types. (2) 2004 Indian Ocean Tsunami detail. (3) Cyclones formation + naming + climate change. (4) Disaster management Sendai framework.
Climate change connection: Stronger storms (more SST energy), rapid intensification, slower movement (more rain), sea-level rise worsens storm surge, more wildfire conditions, drought intensification, glacier melt floods.

அலகு 7 — இலங்கையில் இயற்கை இடர்கள்

Quick numbers: SL hazards — Aranayake 2016 (127 deadliest landslide); 1978 cyclone (700+ dead); 2004 tsunami (35K dead); Peraliya train (1700); lightning (50+/yr — world's highest per capita).
Year-event pairs: 1964 Dec Batticaloa cyclone; 1978 Nov cyclone deadliest; 1986 Walapane landslide 122; 2003 May floods 260+; 2004 Dec 26 tsunami; 2014 Meeriyabedda landslide; 2016 Aranayake + Roanu; 2017 Bulathkohupitiya; 2024 Remal + multi.
10 landslide districts memorize: Nuwara Eliya, Kandy, Badulla, Ratnapura, Matale, Kegalle, Kalutara, Galle, Matara, Hambantota.
எளிதில் தவறும்: (1) SL plate interior — no quakes/volcanoes; tsunami came from elsewhere. (2) "Cyclone" not "typhoon" (Indian Ocean naming). (3) DMC=operational; NCDM=policy. (4) NBRO=landslide. (5) Aranayake 2016 (not Walapane 1986) deadliest single landslide. (6) Lightning world's highest casualties per capita — true SL fact.
கட்டுரைக்குத் தயார்: (1) Multiple hazards overview. (2) 2004 tsunami SL impact + response + reform. (3) DM framework: Act 2005 + NCDM + DMC + Sendai alignment.
Future challenges: Climate change intensifies (more cyclones, floods, droughts, sea level). Coastal vulnerability rising. Aging infrastructure. DRM budget constraints post-2022 crisis. Equity in north-east.
Key institutions to remember: DMC (operational coordination), NBRO (landslides), Met Dept (weather), Irrigation Dept (floods), CCD (coastal), CEA (pollution), NARA (marine), GSMB (seismic). Tri-Services emergency response.
Build Back Better principle = global Hyogo 2005 → Sendai 2015; SL adopted post-tsunami.

அலகு 8 — காலநிலை மாற்றங்கள்

Critical Numbers: +1.1°C global warming. CO₂ 280→425+ ppm. Sea level +25cm. Methane GWP 84×. SL emissions 1 ton/capita.
Key Years: 1987 Montreal · 1988 IPCC · 1992 UNFCCC Rio · 1997 Kyoto · 2015 Paris (COP21).
Recent COPs: COP26 Glasgow 2021 (coal). COP27 Sharm 2022 (Loss & Damage). COP28 Dubai 2023 (fossil fuel transition). COP29 Baku 2024 ($300B finance).
Paris targets: 1.5°C / 2°C. NDCs every 5 yrs. $100B/yr finance. Net-zero 2050 (developed) / 2060 China / 2070 India.
SL NDC: 14.5% reduction by 2030; 70% RE by 2030; carbon neutral 2050.
எளிதில் தவறும்: (1) Weather ≠ Climate ≠ Climate Change. (2) Natural greenhouse essential; enhanced is problem. (3) CO₂ 75% but methane 84× stronger short-term. (4) Kyoto = developed-only binding; Paris = universal voluntary. (5) Montreal Protocol = ozone (separate, very successful); UNFCCC/Paris = climate. (6) Mitigation (reduce GHG) ≠ Adaptation (cope with impacts). (7) Sea level rise = 25 cm + accelerating (not small).
கட்டுரைக்குத் தயார்: (1) Climate change definition + greenhouse mechanism + GHGs + causes. (2) Observed effects across temp/ice/sea/weather/ecology/humans. (3) International treaties + Paris + COPs + SL commitments.
Mitigation strategies: Renewable energy, EVs, energy efficiency, carbon pricing, reforestation, sustainable agriculture, methane reduction, CCS, green hydrogen.
Adaptation strategies: Coastal protection (sea walls + mangroves), climate-resilient crops, water management, disaster preparedness, infrastructure adjustment, health systems, insurance.
Climate justice: Top 10% richest emit 50%; bottom 50% emit 10%. Historic emitters (USA, EU) bear more responsibility. SL/Africa/small islands suffer most despite minimal contributions.

அலகு 9 — 1:50,000 இலங்கையின் இடவிளக்கப் படங்கள்

Quick facts: 92 sheets @ 1:50,000. 1 cm = 500m, 2 cm = 1 km, 1 cm² = 0.25 km². Each sheet 5'×5' graticule. CI typically 10-20 m. Index contour every 5th = thicker.
Grid mnemonic: "Along corridor, then up stairs" = Eastings (left-right) FIRST, Northings (bottom-up) SECOND. "E before N" alphabetically.
4-fig vs 6-fig: 4-fig identifies 1 km × 1 km square; 6-fig pinpoints ~100m × 100m point. Format 6-fig: EEEnnn (e.g., "346 563").
Contour rules summary: Brown lines. Close=steep; spaced=gentle. Concentric closed=peak. V up-slope=ridge; V down-slope=valley. Index contour every 5th = thicker.
8 drainage patterns (memorize): Dendritic, Trellis, Rectangular, Radial, Centripetal, Parallel, Annular, Deranged. Most common in SL = Dendritic.
Colors: Blue water; Brown contour; Red roads/admin; Black rail/settlement; Green paddy; Yellow plantation/track.
Calculation formulas: Distance = cm × 0.5 km/cm. Area regular = L × B × 0.25 km²/cm². Area irregular = squares × 1 km². Gradient = rise/run.
Cross-section: Strip paper along section; mark contour crossings; plot on graph; ~10× vertical exaggeration for visibility.
எளிதில் தவறும்: (1) Eastings before Northings (E before N). (2) 4-fig vs 6-fig confusion. (3) 1 cm² = 0.25 km² (NOT 1 km²!). (4) V up-slope = ridge, NOT valley. (5) Gradient should be ratio or %. (6) Use scale 0.5 km/cm consistently. (7) Brown = contour (NOT blue or red).
கட்டுரைக்குத் தயார்: (1) Sheet basics + grid system + 4/6-fig refs + calculations. (2) Contour interpretation + landforms + 8 drainage patterns + river features. (3) Cultural features + symbols + integrated map analysis.
Sample exam tasks: (1) Give 6-fig grid reference. (2) Calculate distance straight + along road. (3) Identify slope type between two contours. (4) Name drainage pattern. (5) Identify a landform. (6) List settlement type + transport. (7) Calculate area. (8) Calculate gradient. (9) Draw cross-section. (10) Suggest land use possibilities.
SL-specific knowledge: Major rivers (Mahaweli, Kelani, Kalu); Tea/coconut/rubber zones; Wet/dry zone; Settlement patterns (dispersed in dry zone, nucleated in wet); Survey Department Kirulapone.

அலகு 10 — தரவுகளை விளக்குவதற்காக வரைபுகளைப் பயன்படுத்தல்

Memorize graph choice matrix: Trend=Line; Categories=Bar; Proportion=Pie; Climate=Climograph; Correlation=Scatter; Distribution=Histogram; Spatial=Choropleth; Demography=Pyramid.
Pie angle formula: (value/total) × 360°. OR % × 3.6.
Pie angle key values: 25%=90°; 50%=180°; 75%=270°; 100%=360°.
Must-have elements every graph: Title + axes labels (with units) + scale + legend (if needed) + source.
Climograph convention: X=12 months; Left Y=Temp °C (line); Right Y=Rainfall mm (bars).
SL climate zones (memorize): Wet zone (Colombo 2400mm, Nuwara Eliya 1900mm), Dry zone (Anuradhapura 1300mm, Hambantota 1000mm), Intermediate.
எளிதில் தவறும்: (1) Pie chart NOT for time-series. (2) Bar chart NOT for proportions. (3) Climograph temperature is LINE not bar. (4) Pie angle = ×360 not ×100. (5) Truncated Y-axis misleads. (6) Don't use 3D effects.
SL Geography applications: Population growth (line); Districts compare (bar); Ethnic composition (pie); Climate (climograph); Income vs literacy (scatter); Density by district (choropleth); Age-sex (pyramid).
கட்டுரைக்குத் தயார்: (1) Graph types + when to use. (2) Climograph construction + reading + zones. (3) Pie chart construction + interpretation + best practices.
Practical exam tasks: (1) Given data → recommend graph type + reason. (2) Calculate pie angle for given percentage. (3) Construct climograph from monthly data. (4) Identify climate zone from given climograph. (5) Identify common errors in shown graph.
Reading skills: What is highest/lowest? Calculate range. Calculate total. Identify trend. Compare with another graph. Identify pattern type. Suggest interpretation.
Best practices: Simplicity + clarity + truthfulness > decoration. Choose right type for data. Include source. Use color thoughtfully. Avoid 3D + truncation + clutter.