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Natural Hazards and Disasters
Natural hazards are severe and extreme weather and climate events that occur naturally in all parts of the world, although some regions are more vulnerable to certain hazards than others. Natural hazards become natural disasters when people’s lives and livelihoods are destroyed.
Natural hazard events can be grouped into two broad categories:
Geophysical hazards encompass Geological and Meteorological phenomena such as earthquakes, coastal erosion, volcanic eruption, cyclonic storms, and drought.
Biological hazards can refer to a diverse array of disease and infestation. Other natural hazards such as floods and wildfires can result from a combination of geological, hydrological, and climatic factors.
An avalanche occurs when large snow (or rock) mass slides down a mountainside. An avalanche is an example of a gravity current consisting of granular material. In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by the size or severity of consequences resulting from the event.
An earthquake is a phenomenon that results from a sudden release of stored energy that radiates seismic waves. At the Earth’s surface, earthquakes may manifest with shaking or displacement of the ground; when the earthquake occurs on the seafloor, the resulting displacement of water can sometimes result in a tsunami. Most of the world’s earthquakes (90%, and 81% of the largest) take place in the 40,000-km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate. Many earthquakes happen each day, few of which are large enough to cause significant damage.
A tsunami is also known as a seismic sea wave or as a tidal wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Tsunamis can be caused by undersea earthquakes such as the 2004 Boxing Day tsunami, or by landslides such as the one in 1958 at Lituya Bay, Alaska, or by volcanic eruptions such as the ancient eruption of Santorini. On March 11, 2011, a tsunami occurred near Fukushima, Japan and spread through the Pacific.
Coastal erosion is a physical process by which shorelines in coastal areas around the world shift and change, primarily in response to waves and currents that can be influenced by tides and storm surge. Coastal erosion can result from long-term processes as well as from episodic events such as tropical cyclones or other severe storm events.
A lahar is a type of natural event closely related to a volcanic eruption and involves a large amount of material originating from an eruption of a glaciated volcano, including mud from the melted ice, rock, and ash sliding down the side of the volcano at a rapid pace. These flows can destroy entire towns in seconds and kill thousands of people, and form flood basalt. This is based on natural events.
A landslide is the movement of rock, earth, or debris down a sloped section of land. Landslides are caused by rain, earthquakes, volcanoes, or other factors that make the slope unstable.
A sinkhole is a localized depression in the surface topography, usually caused by the collapse of a subterranean structure such as a cave. Although rare, large sinkholes that develop suddenly in populated areas can lead to the collapse of buildings and other structures.
A volcanic eruption is a point in which a volcano is active and releases its power, and the eruptions come in many forms. They range from daily small eruptions which occur in places like Kilauea in Hawaii, to mega-colossal eruptions (where the volcano expels at least 1,000 cubic kilometres of material) from super-volcanoes like Lake Taupo (26,500 years ago) and Yellowstone Caldera. According to the Toba catastrophe theory, 70 to 75 thousand years ago, a supervolcanic event at Lake Toba reduced the human population to 10,000 or even 1,000 breeding pairs, creating a bottleneck in human evolution. Some eruptions from pyroclastic flows, which are high-temperature clouds of ash and steam that can travel down mountainsides at speed exceeding an airliner.
A blizzard is a severe winter storm icy and windy conditions characterized by low temperature, strong wind and heavy snow.
Scientists warn that global warming and climate change may result in more extensive droughts in coming years. These extensive droughts are likely to occur within the African continent due to its very low precipitation levels and high climate.
A hailstorm is a natural hazard where a thunderstorm produces numerous hailstones which damage the location in which they fall. Hailstorms can be especially devastating to farm fields, ruining crops and damaging equipment.
A heatwave is a hazard characterized by heat which is considered extreme and unusual in the area in which it occurs. Heatwaves are rare and require specific combinations of weather events to take place, and may include temperature inversions, katabatic winds, or other phenomena. There is potential for longer-term events causing global warming, including stadial events (the opposite to glacial “ice age” events), or through human-induced climatic warming.
A maelstrom is a very powerful whirlpool. It is a large, swirling body of water with considerable downdraft. There are virtually no documented accounts of large ships being sucked into a maelstrom, although smaller craft and swimmers are in danger. Tsunami-generated maelstroms may even threaten larger crafts.
Hurricane, tropical cyclone and typhoon are different names for the same phenomenon: a cyclonic storm system that forms over the oceans. It is caused by evaporated water that comes off the ocean and becomes a storm. The Coriolis effect causes the storms to spin, and a hurricane is declared when this spinning mass of storms attains a wind speed greater than 74 mph (119 km/h). Hurricane is used for these phenomena in the Atlantic and eastern Pacific Oceans, tropical cyclone in the Indian, and typhoon in the western Pacific.
An ice storm is a particular weather event in which precipitation falls as ice, due to atmospheric conditions. It causes damage.
A tornado is a natural disaster resulting from a thunderstorm. Tornadoes are violent, rotating columns of air which can blow at speeds between 50 mph (80 km/h) and 300 mph (480 km/h), and possibly higher. Tornadoes can occur one at a time or can occur in large tornado outbreaks associated with supercells or in other large areas of thunderstorm development. Waterspouts are tornadoes occurring over tropical waters in light rain conditions.
Geomagnetic storms can disrupt or damage technological infrastructure and disorient species with magnetoception.
A waterspout is an intense columnar vortex (usually appearing as a funnel-shaped cloud) that occurs over a body of water. They are connected to a towering cumuliform cloud or a cumulonimbus cloud. In the common form, it is a non-supercell tornado over water
A flood results from an overflow of water beyond its normal confines of a body of water such as a lake, or the accumulation of water over land areas.
Wildfire is a fire that burnt in an uncontrolled and unplanned manner. Wildfires can result from natural occurrences such as lightning strikes or from human activity.
Natural Hazards and Disasters by High Powered Committee (HPC) in India
High Powered Committee (HPC) was constituted in August 1999 under the chairmanship of J.C. Pant. The mandate of the HPC was to prepare comprehensive model plans for disaster management at the national, state and district levels. This was the first attempt in India towards a systematic comprehensive and holistic look at all disasters.
Thirty-odd disasters have been identified by the HPC, which were grouped into the following five categories, based on generic considerations:
|1. Water and Climate||3. Biological|
Tornadoes and hurricanes (cyclones)
Heatwave and cold wave
4. Chemical, industrial and nuclear
Chemical and Industrial disasters
Major building collapse
Serial bomb blasts
Festival related disasters
Electrical disasters and fires
Air, road, and rail accidents
|Landslides and mudflows
Dam failures and dam bursts
Mitigation Strategies for Natural Hazards and Disasters
Mitigation refers to long-term risk reduction measures, which are intended to minimise the effects of a hazard; for example, dam construction is considered an activity that mitigates the effects of droughts. Hence, “Mitigation involves not only saving lives and injury and reducing property losses, but also reducing the adverse consequences of natural hazards to economic activities and social institutions.”
According to Coburn Sspence, Pomonis (1994 in the DMTP, UNDP), Mitigation is defined as “a collective term used to encompass all activities undertaken in anticipation of the occurrence of a potentially disastrous event, including long term preparedness and risk reduction measures…. It has occasionally been defined to include post-disaster response, which makes it equivalent to disaster management.”
The mitigation strategy is made up of three main required components: mitigation goals, mitigation actions, and an action plan for implementation. These provide the framework to identify, prioritize and implement actions to reduce risk to hazards.
Mitigation mainly focuses on minimising the destruction and disruption by a hazard and offers long term cost-effective methods of dealing with or managing natural disasters.
According to Carter (1991), there are two approaches to mitigation:
- Structural Approach
- On-structural Approach
In fact, non-structural measures complemented by structural measures are an effective means of disaster mitigation.
A structural approach for mitigation may refer to both:
1. Engineered Structures: Engineered structures involve architects and engineers during the planning, designing and construction of structures, including buildings, dams, roads, bridges etc.
2. Non-engineered Structures: non-engineered structures are generally constructed by people with the help of local artisans like masons, carpenters etc., using locally available raw material. These structures can be made safer if people are trained and given improved designs. These structures are normally of low-cost but have less strength/resistance for a disaster.
The non-structural approach encompasses those measures that attempt to bring about coordination of efforts between all organisations and persons during all phases of disaster management, training and public awareness, legislation, policymaking, preparing of action plans etc., Such approach to mitigation consists of positive actions through legislation, incentives, educating people, creating community awareness etc.
Some of the non-structural mitigation measures are:
In some of the disasters like flood, cyclone, earthquake etc., more casualties occur because people either live in low flood plains or not follow building codes made for the highly seismic zones or vulnerable cyclone areas. In case people are made to follow safe principles, by-laws and construction on unsafe areas is restricted, the disasters can be mitigated. The Disaster Management Act 2005 includes provisions for institutional and coordination mechanisms for undertaking the preparedness and mitigation measures and strategies for ensuring preparedness and capacity building.
By suitable incentives, people could be encouraged to adopt safety measures.
Insurance of crops, buildings and other infrastructure in the disaster-prone area is another measure.
Training, Education and Public Awareness
Training of public officials at different levels is an essential part of disaster management. The general public should be made aware and kept informed about the nature of hazards to which they are exposed, their vulnerability and available protection measures. Training and education need to target various categories of personnel including school children, craftspersons, technical personnel etc.
To increase the disaster mitigation capacity of a country, institution building is of great importance. Government bodies, departments, NGOs and people should be careful to avoid actions that will further increase a society’s vulnerability. By increasing self -sufficiency, agencies may improve the ability of individuals, families and communities to cope with disaster.
A reliable and timely warning of disasters can save a lot of human lives.
Mitigation Strategies: Government of India Initiatives
The Government of India has also issued guidelines indicating that priority will be given to projects addressing mitigation. We shall now discuss in brief the initiatives of Government of India in the area of disaster mitigation. These shall be categorised into structural and non-structural strategies.
a) Flood Mitigation
Flood mitigation measures have been in place since the 1950s, in the form of embankments, dams and barrages etc. In order to respond effectively to floods, the Ministry of Home Affairs has initiated measures such as drawing up mitigation plans at the state, district, block, village levels, training of elected representatives and officials in flood management. etc.
b) Earthquake Risk Mitigation
A comprehensive programme for earthquake risk mitigation is being taken up. This includes the incorporation of Bureau of Indian Standard (BIS) Codes in building regulations, – town and country planning Acts etc. Especially states in earthquake-prone zones have been requested to incorporate BIS Seismic Codes for construction in the concerned zones. An Expert Committee appointed by the National Core Group for Earthquake Risk Mitigation has submitted its report covering appropriate amendments to the existing Town and Country Planning Acts, Land-use Zoning Regulation, Development Control Regulations and Building By-laws. The Model Building By-laws also covers the aspect of ensuring technical implementation of the safety aspects in all new constructions and upgrading the strength of existing structurally vulnerable constructions.
c) Constitution of Hazard Safety Cells in the States
The states have been advised to constitute Hazard Safety Cells (HSC) headed by Chief Engineer, State Public Works Department with necessary engineering staff so as to establish a mechanism for proper implementation of the building codes in all future government constructions and to ensure the safety of buildings and structures from various hazards.
d) Retrofitting of Lifeline Buildings
The Ministries of Civil Aviation, Railways, Telecommunications, Power, Health and Family Welfare have been advised to take appropriate action for a detailed evaluation of retrofitting of lifeline buildings located in seismically vulnerable zones to comply with BIS norms.
e) Mainstreaming Mitigation in Rural Development Schemes
Rural housing and community assets for vulnerable sections of the population are created on a fairly large scale by the Ministry of Rural Development under the Indira Awaas Yojna (IAY) (Now, Pradhan Mantri Awaas Yojna), Sampooran Grameen Rojgar Yojna (SGRY). This includes the construction of compact housing units, community assets such as community centres, recreation centres, Anganwadi centres etc. Efforts are being made to ensure that buildings constructed under this scheme are disaster-resistant.
f) National Cyclone Mitigation Project
This project drawn up in consultation with the cyclone-prone states envisages construction of cyclone shelters, coastal shelterbelt plantation, strengthening of warning systems etc.
g) Landslide Hazard Mitigation
A National Group has been constituted under the Chairmanship of Secretary, Border Management, with the collaboration of Department of Science and Technology, Road Transport and Highways, Geological Survey of India, National Remote Sensing Agency, to examine several aspects of landslide mitigation, including landslide hazard zonation, early warning system etc.
a) Human Resource Development
Human resource development at all levels is critical for an institutionalising disaster mitigation strategy. The National Centre for Disaster Management (NCDM) at the national level has been upgraded and designated as the National Institute of Disaster Management (NIDM).
This is entrusted with the task of developing training modules at different levels, undertaking training of trainers, organising training programmes, developing national-level information base on disaster management policies, prevention mechanism, mitigation measures etc. Disaster management has been incorporated in the training curricula of All India Services with effect from 2004-2005. There is a separate faculty in the area of Disaster management in 29 State level training institutes.
b) Capacity Building of Engineers and Architects in Earthquake Risk Mitigation
This activity is being initiated under two national programmes for Capacity Building for Earthquake Risk Mitigation. Around 10,000 engineers and 10,000 architects in the states will be imparted training in seismically safe building designs and related techno-legal requirements. Seven National Resource Institutions have been designated as National Resource Institutions for imparting training to faculty of select State Engineering and Architecture colleges, and also put in place a framework for mandatory registration and compulsory competency assessment of the practising architects.