Full study notes for BEVAE-181 Block 4 Unit 13. Covers human population growth from 5 million (8000 BC) to 7.6 billion (2018) with the J-curve diagram, population milestones, India's population data, environmental degradation from human activities, WHO definition of health, community health, three influences on individual health (genetic, behavioural, environmental with all five sub-types), natural disaster types (atmospheric, hydrological, geological, biological), India's five seismic zones, Richter scale, floods and cyclones, the 2004 Indian Ocean Tsunami case study (magnitude 9.0, 15m waves, mangroves as natural defence), Rajasthan drought 2000, water harvesting measures, the four-stage disaster management cycle (pre-planning, preparedness, response, recovery), UNEP APELL programme, resettlement and rehabilitation concerns, and three case studies — Taj Trapezium Zone, Chipko Movement, and Silent Valley Movement. Free PDF download.
Unit 13 · Index
Human is the only life form to initiate drastic interventions in nature. As populations grew and industrialisation accelerated, the symbiotic relationship between humans and nature was replaced by destructive dependence. This unit covers population growth trends, environmental degradation, human health and community welfare, natural disasters (earthquakes, floods, cyclones, tsunamis, droughts) and their management, resettlement issues, and landmark people's movements (Chipko, Silent Valley, Taj Trapezium).
Man has always been using natural resources around his dwellings to meet his basic, social and cultural needs. Customs, traditions, practices, beliefs, and rules ensured a balance between human needs and environmental conservation in ancient times. However, with the passage of time, this symbiotic relationship was gradually replaced by destructive dependence. Humans apparently forgot that the ecosystem has a certain carrying capacity that reflects a limit to its exploitability.
Modern Homo sapiens appeared ~50,000 BC. At the dawn of agriculture (~8,000 BC), world population was ~5 million. Population remained relatively small and stable for millennia — occasional declines (e.g., bubonic plague in 14th century killed more than half the population of Europe and Asia).
| Milestone | Time to Reach | Key Factor |
|---|---|---|
| 0 → 1 billion | Several thousand years (reached ~1800) | Slow agricultural growth; high death rates from disease + famine |
| 1 → 2 billion | Only 80 years (1800–1880) | Industrial Revolution; better sanitation; cities grew rapidly |
| 2 → 4 billion | Only 45 years | Medical advances; antibiotics; drastic fall in death rates |
| Current (2018) | 7.6 billion; +1.18%/year | Improved nutrition; better healthcare; more babies surviving |
| Projected | 8.6B (2030s), 9.8B (2050s), 11.2B (2100) | Ongoing growth. World's food resources can sustain max 10B! |
| India 2018 | 1,357 million = 17.74% of world population | Was 350 million at independence (1947). 3× increase in ~70 years |
Much before globalisation, natural calamities (floods, earthquakes, volcanoes, forest fires) were wreaking havoc. But with rapid industrialisation, exploitation of non-renewable resources, construction of dams, deforestation, and human greed for quick returns, the frequency and severity of calamities has escalated dramatically. Human-made disasters (nuclear accidents, industrial accidents, toxic waste disposal, oil spills, greenhouse gases) have created threats to humanity's very existence.
⚠️ The Thin Line: The margin between natural calamities and human-made disasters is becoming thinner gradually. Some scientists argue all environmental calamities are ultimately human-made; others argue that development cannot occur without calculated risks. The issue at stake is the survival of humanity.
i) Nomadic ii) 1800, Growth iii) 2018 iv) Natural
Health = "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." Good health involves continuous adaptation to changing physical, biological, and social environments throughout life.
"The aspect of public health that is concerned with all external conditions — all forms of life, substances, forces, problems and challenges and any other condition in the surroundings of human beings — that may exert an influence on their health and well-being."
Community health encompasses the entire gamut of community-organised efforts for maintaining, protecting and improving the health of the people. Involves motivation of individuals and groups to change patterns of behaviour. Objectives of public health include:
🧬 Genetic vs Gene-Environment Interaction: Purely hereditary diseases (passed directly from parents): Phenylketonuria, Haemophilia, Mongolism, Sickle-cell anaemia, Thalassemia. Diseases due to gene-environment interaction (would not occur if environment is favourable): Allergies, Diabetes, Hypertension, Schizophrenia — triggered by nutrition, stress, hormones, drugs, and other environmental factors.
A) Purely genetic/hereditary: iii) Haemophilia vi) Sickle-cell anaemia vii) Mongolism (Down's syndrome). Due to genetic + environment interaction: i) Schizophrenia, ii) Hypertension, iv) Diabetes, v) Allergies. Behavioural: viii) Alcoholism.
B) Environmental influences: a) Toxin → Chemical b) Radiation → Physical c) Stress → Psychological d) Microorganism → Biological e) Neglect → Sociological
A disaster = an event that causes damage, economic disruption, loss of human life and deterioration in the health and health services on a scale sufficient to warrant an extraordinary response from outside the affected community.
Global pattern: Asia is more prone to natural calamities. For each major calamity in Europe/Australia → 10 in Latin America and Africa → 15 in Asia. India: 28,777 killed + 144 million affected (annual average 2005–2014).
Earthquakes occur due to vibrations of Earth produced by release of energy — radiating in all directions from the source (epicentre). Also caused by atomic explosions, volcanic eruptions, or large reservoir hydrostatic pressure.
Richter Scale: Describes amplitude of earthquake wave radiating from the epicentre — related to energy released. Measured by seismograph. Training public in Earthquake Resistance Construction in earthquake-prone areas is key preventive measure.
A flood = the discharge of water that exceeds the canal capacity of the river. Most common of all natural calamities. Bangladesh and India together account for over two-thirds of global death count each year.
Causes of floods: Climate extremes (heavy/prolonged rainfall), melting of snow and ice, collapse of dams, deforestation and landslides, silting of river beds (reduces carrying capacity), lack of coordination between adjoining countries/states.
Mitigation: Construction of dams/reservoirs at appropriate places, strengthening embankments, improving carrying capacities of rivers by periodic deepening, weather forecasting, flood plain management techniques.
Cyclones are caused in tropical belt when sea water gets heated to 27°C+ so that low pressure areas develop above water. Low pressure areas remain stationary for 3–4 days and draw energy from sea surface. As pressure falls, wind speed increases and cloud bursts start spiralling around the centre → cyclone moves landward.
🌀 1970 Bay of Bengal Cyclone: A tropical cyclone in northern Bay of Bengal (1970) caused tidal waves of 6 metres height, killing 3,00,000 people and destroying 65% of the total fishing capacity of the coastal region. Today, with weather prediction and remote sensing satellites, it is possible to predict and monitor cyclones — but damage remains severe.
A tsunami = a wave in the ocean or lake created by a geological event. Also called tidal waves or seismic sea waves. Most often caused by earthquakes and landslides. Volcanic eruptions can also cause tsunamis.
Triggered by earthquake of magnitude 9.0 on Richter scale at 3.4°N, 95.7°E off the coast of Sumatra, Indonesia at 06:29 hrs IST. Tsunami devastated shores of Indonesia, Sri Lanka, India, Thailand and other countries with waves up to 15 metres high. Even reached east coast of Africa — 4,500 km west of the epicentre.
Death Toll: Indonesia: ~79,900 · Sri Lanka: ~41,000 · India: ~10,000 · Thailand: ~4,000.
Mangroves as Natural Defence: Dense mangrove forests stood like a wall to save coastal communities. Mangroves in Pitchavaram and Muthupet bore the brunt of the tsunami — communities behind them were significantly protected (M.S. Swaminathan Research Foundation).
After Response: India established indigenous warning system — Deep Ocean Assessment and Reporting System with ~20 data buoys + software to predict tsunami location, time and height. India tied up with Pacific Tsunami Warning Centre and countries like Indonesia, Thailand, and Myanmar.
A drought = a prolonged period of unusually dry weather, with little rainfall, in a region where rains are normally expected. A "creeping calamity" — develops slowly and has prolonged existence. Often lasts for years.
Rajasthan (largest state, ~54 million people) suffered severe drought in 2000. 31 of 32 districts affected (25 severely). 73.64% of villages affected — 33.04 million people and 39.97 million cattle. Out of 2,647 major water reservoirs, only 300 were filled. Nearly 75–100% of crops destroyed → mass migration for employment.
Three categories of drought impact: Economic (loss of crop, dairy, livestock, fishery produce), Environmental (damage to plant and animal species, soil erosion), Social (food shortage, health damage, conflicts between water users).
Human causes aggravating drought: Felling trees for firewood, deforestation for agriculture/housing, mining, unscientific farming, indiscriminate drawing of groundwater. Groundwater = 38% of India's water; supplies drinking water to more than 97% of rural population.
💧 Water Harvesting Measures: Capturing runoff from rooftops; capturing runoff from local catchments; capturing seasonal floodwaters from local streams; conserving water through watershed management. Serves purposes: drinking water, irrigation, groundwater recharge, reducing storm water discharges, reducing seawater ingress in coastal areas. Example: Hyderabad's Neeru-Meeru (Water and You) programme.
a)–v b)–i c)–ii d)–iii e)–iv
Emergency preparedness = a programme of long-term development activity whose goal is to strengthen the overall capacity and capability of a country to manage efficiently all types of emergencies and bring about an orderly transition from relief through recovery and back to sustainable development. It is an ongoing multi-sectoral activity forming an integral part of the national system.
The fundamental goal of UNEP's disaster management programme is to reinforce the centrality of environmental concerns in disaster management. Cornerstone: adoption of preventive strategies and practical measures to reduce potential loss of human lives, property, and the environment.
APELL (Awareness and Preparedness for Emergencies at Local Level): Developed in conjunction with governments and industry. Recognises that incidence and effects of environmental disasters can be reduced by prevention and preparedness initiatives at the local level. Successfully introduced to more than 30 countries and in more than 80 industrial communities worldwide.
Steps to prevent/mitigate droughts: (1) Constructing reservoirs in drought-prone areas to store rainwater; (2) Water harvesting: capturing rooftop runoff, local catchment runoff, seasonal floodwaters, and watershed management; (3) Educating people in water conservation and scientific farming methods; (4) Optimal use of groundwater — avoid indiscriminate drawing; (5) Stopping deforestation — preserve tree cover to maintain water cycles; (6) Avoid unscientific farming and mining that destroys aquifer recharge zones; (7) International/regional cooperation in water sharing and drought monitoring.
Both natural and human-made disasters force people to move out of their land. Examples: Tsunami South Asia 2004, Latur and Gujarat earthquakes, Orissa super-cyclone, floods, droughts, Bhopal gas tragedy, derailment of trains, Himalayan landslides (nature + faulty planning).
Development projects (roads, dams, mining) involve displacement of people — often paid little attention by project authorities despite long planning periods. Those who give up assets for development projects should be recognised as stakeholders and should benefit from development.
Build earthquake-proof houses; gather advance information about cyclones and arrange timely evacuation; build appropriate bunds in flood-prone areas; maintain bridges and transportation infrastructure. Primary necessity = creating awareness among people AND administrative personnel.
Shelter is critical to survival. Provides security, personal safety, and supports human dignity. More secure shelter in safer settlement = immediate and sustainable physical foundation for livelihoods. Transitional reconstruction begins immediately after disaster and can occur over years.
Though legislations are foundations of environmental protection, Public Interest Litigations and People's Movements have also played a very important role. Three landmark cases:
From the late 19th century, Himalayan forests were subject to rapid exploitation causing severe ecological problems: rapid soil erosion, growing frequency of floods, reduction in firewood and fodder, landslides, disappearance of water table. People also resented conversion of natural forests into monoculture plantations.
Start: 1970s — Voluntary organisations Gangotri Gram Swarajaya Sangh (GGSS, Uttarakashi) and Dasholi Gram Swarajaya Mandal (DGSM, Gopeshwar) started Chipko Movement. Led by Chandi Prasad Bhatt and Sunderlal Bahuguna in Garhwal Himalayas.
"Chipko" means to hug the tree. Volunteers threatened to hug trees if saws came near them. Popularised through folk songs, street plays, and widespread campaign. Slogan: "What do the forests bear? Soil, water and pure air. Soil, water and pure air are the basis of life."
Outcomes: Government replaced contractor system, formed Uttar Pradesh Forest Department Corporation (UDFDC). Forest activities encouraged through local cooperatives. 1981: In response to Bahuguna's indefinite fast, Government constituted an 8-member expert committee. Government later put a fifteen-year moratorium on commercial tree felling in Uttarakhand Himalayas.
Silent Valley is the narrow valley of the Kunthi River in Kerala, at high elevation. Its 8,950 hectares of rainforest is rich with valuable plants and animals. In 1973, Kerala state government decided to build a dam across the gorge for hydroelectric power — which would have drowned valuable forest and threatened wildlife. Even the government's own ecological task force expressed dissatisfaction over the loss of forest and wildlife.
Movement: By 1979, students, voluntary organisations like Kerala Sastra Sahitya Parishad (KSSP), science forums, teachers, progressive citizens, and journalists began working against the project. In 1979, Save Silent Valley Committee was formed.
Outcome: Hue and cry led then Prime Minister Mrs. Indira Gandhi to set up a high-level technical committee chaired by Prof. M.G.K. Menon. Committee recommended the project should not be proceeded with, and that the Valley should be preserved as a precious biosphere reserve. Government accepted the recommendation.
i) Disasters ii) Shelter iii) Supreme Court iv) Environmentalists v) Silent Valley
Exam-style questions from the IGNOU textbook.
Factors for rapid population growth: (1) Industrial Revolution (post-1800) — cities grew rapidly, goods and services became available, living standards improved; (2) Medical advances — progress in medical sciences, antibiotics, vaccines drastically reduced death rates; (3) Improved sanitation — better hygiene reduced deaths from communicable diseases; (4) Improved nutrition — better food supply, green revolution; (5) Increased birth rates — in agricultural societies, children are assets who help with farming.
Importance of containing population growth: More people = more resources consumed + more waste = more environmental degradation. The world's food resources can sustain a maximum of only 10 billion people. Already: 1 billion+ lack safe drinking water; millions face malnutrition. Population growth leads to deforestation, overexploitation of resources, biodiversity loss, climate change, and poverty.
Causes of Floods: Heavy/prolonged rainfall; melting of snow and ice; collapse of dams; deforestation and landslides (reduce water absorption → more runoff); silting of river beds (reduces carrying capacity); lack of coordination between adjoining countries/states.
Mitigation — Floods: Construction of dams/reservoirs at appropriate places; strengthening embankments on rivers and canals; periodic desilting and deepening of rivers; weather forecasting; flood plain management techniques; weather early warning systems.
Mitigation — Cyclones: Advanced weather prediction through remote sensing satellites and international cooperation; monitoring cyclone movements to pinpoint landfall; well-planned evacuation procedures; pre-positioning relief materials.
Mitigation — Tsunamis: India established Deep Ocean Assessment and Reporting System (~20 data buoys) + software to predict tsunami location, time and height. International cooperation with Pacific Tsunami Warning Centre and neighbouring countries. Preserving mangroves = natural first line of defence (proved effective in 2004).
a) Taj Trapezium Zone (TTZ): Area of 10,400 sq.km around Taj Mahal. Sulphur dioxide from industries (iron foundries, Mathura refinery, Firozabad glass factories, brick kilns) reached levels 10× above standard, forming highly corrosive sulphuric acid (SO₂ + moisture → H₂SO₄). Mahesh Chandra Mehta filed PIL in Supreme Court (1984). SC ruled in 1996 ordering major industries to install pollution controls or relocate; 292 coal industries ordered to switch to natural gas or relocate by April 30, 1997. In 1997 SC ordered closure of 53 iron foundries and 107 other factories. SC also banned cars/parking within 500m of Taj's walls. Mehta won Ramon Magsaysay Award 1997.
b) Silent Valley Movement: Silent Valley = 8,950 ha rainforest in Kunthi River valley, Kerala. In 1973, Kerala government planned a dam that would have flooded the forest. By 1979, Kerala Sastra Sahitya Parishad (KSSP), students, scientists, and citizens formed Save Silent Valley Committee. PM Indira Gandhi set up high-level committee (chaired by Prof. M.G.K. Menon) which recommended not to proceed with the project. Valley preserved as biosphere reserve. Regarded as one of India's most important ecological movements.
c) Chipko Movement: Himalayan forests were being rapidly exploited, causing soil erosion, floods, loss of firewood/fodder. GGSS and DGSM organisations started movement in 1970s; led by Chandi Prasad Bhatt and Sunderlal Bahuguna. "Chipko" = hug the tree — volunteers threatened to embrace trees to stop felling. Used folk songs, street plays, campaigns. Slogan: "Soil, water and pure air are the basis of life." Government replaced contractor system with UDFDC. In 1981 (after Bahuguna's indefinite fast), Government constituted an expert committee leading to a 15-year moratorium on commercial felling in Uttarakhand Himalayas.
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