Class 11 Geography Chapter 7 – Natural Calamities and Crisis Notes (Earthquake, Tsunami, Flood, Landslide, Disaster Management)

Class 11 Geography Chapter 7 – Natural Calamities and Crisis Notes (Earthquake, Tsunami, Flood, Landslide, Disaster Management)

Class 11 Geography
Published on By Amresh Academy

🌍 Class 11 Geography – Chapter 7

Natural Calamities and Crisis (Notes)

🔰 Introduction

  • Man and nature share a deep relationship.

  • Nature provides happiness 🌱, but sometimes its formidable form brings unhappiness.

  • Humans face calamities like 🌋 volcanoes, 🌪️ cyclones, 🌊 tsunamis, 🌧️ floods, 🌵 droughts, 🌍 earthquakes, famine, etc.

  • Change is the law of nature – some changes are good ✅, while some are disastrous ❌.

  • Natural calamities cause great loss to life and property, hence knowledge & management are important.

⚡ Disaster – Meaning

  • A disaster is an unexpected event caused by forces beyond human control.

  • It occurs suddenly ⏳ and blocks human life activities.

  • Leads to large-scale loss of life and property.

🔄 Difference – Natural Disaster vs Crisis

  • Natural Hazard → Possible danger ⚠️ (risk to life/property).

  • Disaster → Actual destruction 💥 (life loss, economy halted).

  • Both are related but differ in impact level.

🗂️ Classification of Natural Disasters

1️⃣ Atmospheric – Thunderstorms, tornadoes, tropical cyclones, drought, frost. 🌪️
2️⃣ Earthquake Related – Earthquake, volcano, landslide, soil erosion. 🌋
3️⃣ Aquatic – Flood, tsunami, tides, ocean currents, storms. 🌊
4️⃣ Biological – Locust attack, fungi, bacterial/viral infections, dengue, bird flu. 🦠

🏗️ When Development Works Cause Disaster

  • Ignoring environmental conditions while developing can lead to disaster.

  • Example: Building a dam to control floods, but stagnant water later causes epidemics.

  • Hence, development must be eco-friendly and sustainable 🌱.

🛠️ Disaster Prevention & Management

✅ Before Disaster

  • Collect data 📊 & prepare disaster maps.

  • Inform people about risk zones.

✅ During Disaster

  • Rescue & relief work 🚑.

  • Evacuate victims to relief camps.

  • Provide food, water & medical facilities.

✅ After Disaster

  • Arrange rehabilitation for victims 🏠.

🌪️ Cyclonic Disaster

🌬️ Cyclone – Meaning

  • A cyclone is a low-pressure area surrounded by high pressure.

  • Winds blow from all sides → inward spiral movement.

  • Rainfall is 50–100 cm above normal with strong winds.

⚠️ Effects of Cyclones

  • Huge loss of life & property.

  • 🌳 Trees uprooted, 🏢 buildings damaged, ⚡ power lines destroyed.

  • Cause heavy rainfall → floods.

  • Sea cyclones produce high waves → danger to fishermen, sailors, and coastal residents.

🌵 Drought

📖 Meaning

  • Less than normal rainfall in an area for a long time.

🔎 Types of Drought

  1. Meteorological Drought – Insufficient rainfall (lack of rain ☁️).

  2. Agricultural Drought – Crop failure due to water shortage (soil moisture drought). 🌾

  3. Hydrological Drought – Water level in rivers & groundwater drops below limit. 💧

  4. Ecological Drought – Ecosystem productivity decreases due to water scarcity. 🌱

✅ Measures to Prevent Drought

  • Provide drinking water, food, fodder & medicines.

  • Use GIS for groundwater exploration.

  • Rainwater harvesting & build small dams.

  • Interlink rivers – water surplus areas to water deficit ones.

  • Afforestation & plantation to maintain rainfall 🌳.

📌 Exam Tip:

  • Short answers often ask difference b/w disaster & hazard.

  • Long answers include types of drought / effects of cyclone.

  • Flowcharts & maps can be added for better presentation.

🌍 Disaster Management Notes (Class 11 Geography)

🌋 Earthquake (भूकंप)

🔹 Meaning

Earthquake is the sudden shaking (कंपन) of the earth’s surface caused by movements inside the earth’s crust.

⚡ Causes of Earthquake

  • Tectonic movements (भू-पर्पटी की गतिविधियाँ)

  • Volcanic eruptions (ज्वालामुखी विस्फोट)

  • Breaking & sliding of rocks (चट्टानों का टूटना व फिसलना)

  • Mine collapse (खनन क्षेत्र का धँसना)

  • Water accumulation in reservoirs (जलाशयों में पानी का जमाव)

👉 Tectonic movement earthquakes are the most destructive.

🔥 Consequences of Earthquakes

  • Huge loss of life & property

  • Landslides (भूस्खलन)

  • Fire incidents

  • Floods due to dam/embankment breach

  • Tsunami in seas & oceans

🛠️ Measures to Reduce Earthquake Damage

  • Establish Earthquake Control Centres for early warnings

  • Prepare vulnerability maps & educate public

  • Construct earthquake-resistant buildings

  • Use lightweight materials in prone areas

  • Ban high-rise construction in seismic zones

❓ Why more in Himalayas & North-East?

  • Himalayas = Young Fold Mountains (नवगठित पर्वत)

  • Indian Plate still moving northwards → frequent seismic activity

🌊 Tsunami (सुनामी)

🔹 Causes

  • Earthquakes in ocean

  • Submarine landslides

  • Volcanic eruptions under sea

⚡ Effects

  • Huge waves strike like a "water bomb" 💣

  • Destroys houses, villages, crops, electric poles

  • Washes away boats & drags people into sea

  • Greatest threat to coastal residents

🌧️ Floods (बाढ़)

❓ Why floods in India?

  • Heavy rainfall in monsoon

  • Dam/embankment breaches

  • Tropical cyclones

  • Human activities like deforestation & poor planning

🗺️ Flood-Prone Areas in India

  • Most affected: Assam, West Bengal, Bihar

  • North India rivers → Punjab, Uttar Pradesh

  • Rajasthan, Gujarat, Haryana → Flash floods

🛠️ Measures to Prevent Floods

  • Construct embankments & dams

  • Ban construction in upper catchment areas

  • Relocate population from flood plains

  • Cyclone info centres in coastal areas

⚖️ Difference – Eastern vs Western India Floods

  • Eastern Rivers (Brahmaputra, Kosi, Damodar etc.) → Floods almost every year, locals somewhat adapted

  • Western Rivers → Seasonal rivers, low slope → Whenever floods occur → more destruction

🏔️ Landslides (भूस्खलन)

🌍 Vulnerable Areas in India

  • Highly Vulnerable: Himalayas, NE States, Western Ghats, Andaman-Nicobar

  • High Vulnerability: Most Himalayan & NE states (except Assam)

  • Moderate/Low: Ladakh, Spiti, Aravalli, Deccan Plateau, mining zones

🛠️ Measures

  • Avoid road & dam construction in prone areas

  • Promote terrace farming instead of shifting agriculture

  • Farming only on gentle slopes

  • Ban deforestation, encourage afforestation 🌱

📜 Disaster Management Act

🔹 Definition

A disaster = catastrophe, accident or crisis (प्राकृतिक या मानवीय) causing large-scale loss of life, property, and environment.

⏳ Stages of Disaster Management

  1. Pre-Disaster:

    • Data collection, mapping, awareness, planning, prevention

  2. During Disaster:

    • Evacuation, relief camps, supply of food-water-medicines

  3. Post-Disaster:

    • Rehabilitation, rebuilding, capacity building


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