Natural Disasters: Floods, Cyclones and Landslides - Class VIII

The Ganges river system, particularly its northern tributaries originating in the Himalayas, is the primary cause of frequent flooding in the plains of Uttar Pradesh.

Forests naturally absorb water from rainfall and slowly release the water into the rivers. After deforestation, rainfall flows too quickly to the rivers, stripping the topsoil and causing erosion and flooding to occur. When these floods break the river's banks, further problems arise as the path of the river changes and further soil erosion occurs along the river's new path. Deforestation also makes an area more arid, contributing to droughts.

A flood is an overflow of water that submerges land, which is classified as a natural disaster caused by meteorological or hydrological events.

Flash floods are defined by the speed of flooding, not the source or location of flooding. While flash floods are often caused by heavy rainfall, they can also result from other events, such as drain blockages and cloud bursts

A flood is an overflow of water that submerges land which is usually dry. The European Union (EU) Floods Directive defines a flood as a covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide.

Floods are complex events that can vary significantly in their physical characteristics, including the volume of water (size), the velocity of the current, and the duration of the inundation.

A cyclone is a large-scale air mass that rotates around a strong center of low atmospheric pressure. Winds blow inward toward the low-pressure center.

Global meteorological studies generally categorize the world into four major cyclone-prone zones based on the frequency and intensity of tropical storms.

Amritsar is least likely to be affected by a cyclone because the city does not lie near to any coastal area. In India the cyclones generally affect the coastal areas.

Prior planning will help the effects of the storm to be less, reduce potential loss of life and property, and help you to recover faster.

1. Preparedness is a continuous cycle of planning, organizing, training, equipping, exercising, evaluating, and taking corrective action. Training and exercising plans is the cornerstone of preparedness which focuses on readiness to respond to all-hazards incidents and emergencies.
2. Mitigation is the effort to reduce loss of life and property by lessening the impact of disasters and emergencies. Mitigation involves structural and non-structural measures taken to limit the impact of disasters and emergencies.

The three phases of disaster management include:

1. Preparedness 
2. Response 
3. Recovery

The term 'Willy-willy' is a colloquial name used specifically for tropical cyclones that occur in the north-west region of Australia.

Initially Children, Aged Persons and Physically handicapped peoples should be evacuated first because they might panic and may have difficulties in finding a way out. They need external helps to evacuate.

Mangrove forests have complex root systems that stabilize shoreline sediments, dissipate wave energy, and trap coastal soils, thereby effectively preventing coastal erosion.

Landslides represent a wide range of ground movements, including rock falls, slope failures, and debris flows, all categorized under mass wasting.

An avalanche is essentially a landslide of snow, where a large mass of snow and ice moves rapidly down a mountain slope.

Landslides are triggered by factors that reduce the stability of a slope, such as heavy rainfall, tremors (earthquakes), or the inherent instability of the rock/soil structure.

On 30 July 2014, a landslide occurred in the village of Malin in the Ambegaon taluka of the Pune district in Maharashtra, India. The landslide, which hit early in the morning while residents were asleep, was believed to have been caused by a burst of heavy rainfall, and killed at least 151 people. The landslide was first noticed by a bus driver who drove by the area and saw that the village had been overrun with mud and earth. In addition to those dead, more than 160 people, and possibly up to 200, were believed to have been buried in the landslide in 44 separate houses. Rains continued after the landslide making rescue efforts difficult.

Keeping in view the terms of reference of the Core Group, the Government of India has declared the Geological Survey of India as the ‘Nodal Agency’ on 29 January 2004.

Geological Survey of India as a Nodal Agency is responsible for:

1. Coordinating and undertaking geological studies for landslide hazard mitigation
2. Carrying out landslide hazard zonation
3. Monitoring landslides and avalanches
4. Studying the factors responsible for sliding and suggesting precautionary as well as preventive measure
5. National Core Group has finalized the action plan for landslide studies with inputs of GSI and other organization.

A sturzstrom is a long-runout landslide that involves a large volume of rock and debris, often moving at high speeds.

Coastal erosion is confined to southwest monsoon season when the waves are rough. Seawalls and groynes are the major management strategies adopted for coastal protection along Kerala coast. As per Shoreline Change Assessment data, about 63 percent of the coastline of Kerala is eroding.