Disaster ManagementNatural Disasters - Meaning and nature of natural disasters, their types and effects - Floods, drought

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Disaster ManagementNatural Disasters - Meaning and nature of natural disasters, their types and effects - Floods, drought

 

Disasters

The word Disaster is from a Greek word Disaster meaning bad or evil star. Disaster means a situation in which there is a sudden disruption of normalcy within society causing widespread damage to life and property.

Types

1.   Natural [rain, flood, cyclone, storm, landslides, earthquake, volcanoes]

2.   Man made [war including biological, arson, sabotage, riots, accident (train, air, ship), industrial accidents, fires (forest fires), bomb explosions, nuclear explosions and ecological disasters].

Natural disaster

A natural disaster is the effect of a natural hazard (e.g. flood, tornado, volcano eruption, earthquake, or landslide) that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of the population to support or resist the disaster, and their resilience. This understanding is concentrated in the formulation: "disasters occur when hazards meet vulnerability.” A natural hazard will hence never result in a natural disaster in areas without vulnerability, e.g. strong earthquakes in uninhabited areas.

Types of natural disorders

1. Land slide

2. Earthquakes

3. Volcanic eruptions

4. Hydrological disasters (Floods, Limnic eruptions, Tsunami)

5. Meteorological disasters (Blizzards, Cyclonic storms, Droughts, Hailstorms, Heat waves, Tornadoes)

6. Wildfires

7. Health disasters (Epidemics)

8. Space disasters (Impact events, Solar flares, Gamma-ray burst)

when the word disaster is used, it usually means a sudden event, an earthquake, volcanic explosion, a Tsunami, but there are slow onset disasters like drought, or other types of hydro-meteorological emergencies like, floods or cyclones, which may build up over days or weeks; or a sudden large scale epidemic or may include manmade events which may cause large scale damage to lives and properties. Climate change would definitely impact on hydro-meteorological disasters; but the impact of climate change is slow, tedious, bit by bit, and is like a slow illness which one tends to ignore.

The two key areas are the glacier melt in the Himalayas and the problems in the Sunderbans. The slow but definite melting of glaciers would increase the risks of glacial lake outburst, which means a vast quantity of water will flow down resulting in incidents of floods, particularly in the eastern flowing rivers in India while in the long run there would probably be an increase in water shortages. To handle such a situation we can certainly make assessments of the risk involved and to see what sort of action can be taken to anticipate, to ensure that the impact is not quite as large as it could otherwise be. Therefore, the question of climate change requires an examination of all these issues, not just on the basis of historical data, but also on the basis of how these things are likely to change because of climate. We need to be better prepared in anticipation of disasters, and design appropriate strategies for coping with all of these varieties of possible extraordinary events.

Nothing that is being done is going to work unless an effective local governance is in place. It is the arrangements at the local level in the villages and districts which are really going to prepare the country for coping with disasters and climate change.

Hydrological disasters

It is a violent, sudden and destructive change either in quality of earth's water or in distribution or movement of water on land below the surface or in atmosphere.

 

Floods

Principal types and causes

Areal (rainfall related)

Floods can happen on flat or low-lying areas when the ground is saturated or impermeable and water either cannot run off or cannot run off quickly enough to stop accumulating. Localised heavy rain from a series of storms moving over the same area can cause areal flash flooding when the rate of rainfall exceeds the drainage capacity of the area. When this occurs on tilled fields, it can result in a muddy flood where sediments are picked up by runoff and carried as suspended matter or bed load.

Riverine

River flows may rise to floods levels at different rates, from a few minutes to several weeks, depending on the type of river and the source of the increased flow. The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. Localised flooding may be caused or exacerbated by drainage obstructions such as landslides, ice, or debris.

Rapid flooding events, including flash floods, more often occur on smaller rivers, rivers with steep valleys or rivers that flow for much of their length over impermeable terrain. The cause may be localised convective precipitation (intense thunderstorms) or sudden release from an upstream impoundment created behind a dam, landslide, or glacier.

Estuarine and coastal

Flooding in estuaries is commonly caused by a combination of sea tidal surges caused by winds and low barometric pressure, and they may be exacerbated by high upstream river flow.

Coastal areas may be flooded by storm events at sea, resulting in waves over-topping defences or in severe cases by tsunami or tropical cyclones. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category.

Catastrophic

Catastrophic flooding is usually associated with major infrastructure failures such as the collapse of a dam, but they may also be caused by damage sustained in an earthquake or volcanic eruption.

Effects

·         The primary effects of flooding include loss of life, damage to buildings and other structures, including bridges, sewerage systems, roadways, and canals.

·                     Disease spread (typhoid, giardia, cryptosporidium, cholera and many other diseases depending upon the location of the flood) due to contaminated water  Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases.

·                     Damage to roads and transport infrastructure may make it difficult to mobilise aid to those affected or to provide emergency health treatment.

·                     Flood waters typically inundate farm land, making the land unworkable and preventing crops from being planted or harvested, which can lead to shortages of food both for humans and farm animals. Entire harvests for a country can be lost in extreme flood circumstances. Some tree species may not survive prolonged flooding of their root systems 

Secondary and long-term effects

·         Temporary decline in tourism, rebuilding costs, or food shortages leading to price increases is a common after-effect of severe flooding.

Some of the most notable floods include:

·         The Huang He (Yellow River) in China floods particularly often. The Great Flood of 1931 caused between 800,000 and 4,000,000 deaths.

·         The 1998 Yangtze River Floods, in China, left 14 million people homeless.

·         The 2000 Mozambique flood covered much of the country for three weeks, resulting in thousands of deaths, and leaving the country devastated for years afterward.

What to do before a flood:

Avoid building in flood prone areas unless you elevate and reinforce your home. 2. Elevate the furnace, water heater, and electric panel if susceptible to flooding. 3. Install “Check Valves” in sewer traps to prevent floodwater from backing up into the drains of your home. 4. Contact community officials to find out if they are planning to construct barriers (levees, beams and floodwalls) to stop floodwater from entering the homes in your area. 5. Seal the walls in your basement with waterproofing compounds to avoid seepage.

If a flood is likely to hit your area, you should: 1. Listen to the radio or television for information. Be aware that flash flooding can occur. 2. If there is any possibility of a flash flood, move immediately to higher ground. 3. Do not wait for instructions to move. 4. Be aware of streams, drainage channels, canyons, and other areas known to flood suddenly Flash floods can occur in these areas with or without such typical warnings as rain clouds or heavy rain.

If you must prepare to evacuate, you should: 1. Secure your home. If you have time, bring in outdoor furniture. Move essential items to an upper floor. 2. Turn off utilities at the main switches or valves if instructed to do so. Disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.

If you have to leave your home, remember these evacuation tips: 1. Do not walk through moving water. Six inches of moving water can make you fall. If you have to walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you. 2. Do not drive into flooded areas. If floodwaters rise around your car, abandon the car and move to higher ground if you can do so safely. You and the vehicle can be quickly swept away.

Urban Flood: Urban flooding is significantly different from rural flooding as urbanization leads to developed catchments, which increases the flood peaks from 1.8 to 8 times and flood volumes by up to 6 times. Consequently, flooding occurs very quickly due to faster flow times (in a matter of minutes). Urban areas are also centers of economic activities with vital infrastructure which needs to be protected 24x7.

‘Do’s in Urban flood: 1. Raise furniture, electrical appliances on beds and tables. 2. Put sandbags in the toilet bowl and cover all drain holes to prevent sewage back flow. 3. Use bleaching powder and lime to disinfect the surroundings. 4. Use chlorine tablets to purify water before drinking as advised by Health Department. 5. After the flood recedes, watch out for broken electric poles, damaged bridges, broken glass, sharp objects and debris.

Dont’s in Urban flood : 1. Don’t walk through moving water. If you have to walk in water, walk where the water is not moving. 2. Use a stick to check the firmness of the ground in front of you. 3. Don’t get near the electric poles and fallen power-lines to avoid electrocution. 4. Don’t get near the sewage line, gutters, drains, culverts etc. 5. Don’t drive into flooded areas. If floodwaters rise around your car, abandon the car and move to higher ground if you can do so safely. You and the vehicle can be quickly swept away.

 

Droughts

Drought is an extended period of months or years when a region notes a deficiency in its water supply whether surface or underground water. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm the local economy.

 Human activity can directly trigger exacerbating factors such as over farming, excessive irrigation, deforestation, and erosion adversely impact the ability of the land to capture and hold water. Overall, global warming will result in increased world rainfall along with drought in some areas, flooding and erosion will increase in others.

 

Types

As a drought persists, the conditions surrounding it gradually worsen and its impact on the local population gradually increases. People tend to define droughts in three main ways:

1.  Meteorological drought is brought about when there is a prolonged period with less than average precipitation. Meteorological drought usually precedes the other kinds of drought.

2.  Agricultural droughts are droughts that affect crop production or the ecology of the range. This condition can also arise independently from any change in precipitation levels when soil conditions and erosion triggered by poorly planned agricultural endeavors cause a shortfall in water available to the crops. However, in a traditional drought, it is caused by an extended period of below average precipitation.

3.  Hydrological drought is brought about when the water reserves available in sources such as aquifers, lakes and reservoirs fall below the statistical average. Hydrological drought tends to show up more slowly because it involves stored water that is used but not replenished. Like an agricultural drought, this can be triggered by more than just a loss of rainfall.

Effects

·         Diminished crop growth or yield productions and carrying capacity for livestock

·         Dust bowls, themselves a sign of erosion, which further erode the landscape

·         Dust storms, when drought hits an area suffering from desertification and erosion

·         Famine due to lack of water for irrigation

·         Habitat damage, affecting both terrestrial and aquatic wildlife

·         Hunger, drought provides too little water to support food crops.

·         Malnutrition, dehydration and related diseases

·         Mass migration, resulting in internal displacement and international refugees

·         Reduced electricity production due to reduced water flow through hydroelectric dams

·         Shortages of water for industrial users

·         Snake migration and increases in snakebites

·         Social unrest

·         War over natural resources, including water and food

·         Wildfires, such as Australian bushfires, are more common during times of drought.

·         Reduce dilution of pollutants and increase contamination of remaining water sources.

Well-known historical droughts include:

·         1900 India killing between 250,000 to 3.25 million.

·         1921-22 Soviet Union in which over 5 million perished from starvation due to drought

·         1928-30 Northwest China resulting in over 3 million deaths by famine.

·         1936 and 1941 Sichuan Province China resulting in 5 million and 2.5 million deaths respectively.

·         In 2006, states of Australia including South Australia, Western Australia, New South Wales, Northern Territory and Queensland had been under drought conditions for five to ten years. The drought is beginning to affect urban area populations for the first time. With the majority of the country under water restrictions.

·         In 2006, Sichuan Province China experienced its worst drought in modern times with nearly 8 million people and over 7 million cattle facing water shortages.

·         12-year drought that was devastating southwest Western Australia, southeast South Australia, Victoria and northern Tasmania was "very severe and without historical precedent".

·         In 2011, the State of Texas lived under a drought emergency declaration for the entire calendar year. The drought caused the Bastrop fires.

 

Citation of Disaster Mitigation Award to INCOIS

“The Indian National Centre for Information Services (INCOIS) is an autonomous body under the Ministry of Earth Sciences, Government of India set up with a mission to provide ocean information and advisory services to the society, industry, government and scientific community through sustained ocean observations and constant improvements through systematic and focused research.

Initially conceived as a provider of operational data and services, INCOIS has been transformed into a knowledge and information technology enterprise for the oceanic realm. They have carved a niche for themselves by providing operational ocean information to the entire country using advances in Space technology. Ocean science and ICT which is now being adapted by several countries in the Indian Ocean region.

Further, they serve as observer of the Indian Ocean using cutting edge technology, including the Argo profiling floats. INCOIS is the Regional Data Centre and Regional Coordinator of International Agro Project in the Indian Ocean region. It also operates as a secretariat of Regional Alliance for Global Operation Observation System in the Indian Ocean region. Following the Indian Ocean Tsunami in December 2004, the INCOIS was entrusted with the prime responsibility for establishing National Tsunami Early Warning System in collaboration with various national institutes. The system that has been set up comprises a real-time network of Seismic Stations, Bottom Pressure Recorders and Tide gauges to detect Tsunamigenic earthquake and to monitor tsunamis and their arrivals. It operates round the clock on data reception, display, analysis, modeling and decision support system. It generates and disseminates timely advisories to the Emergency Operation Centres of Central and State Governments for further dissemination to the public. For this purpose, a satellite based Virtual Private Network for Disaster Management Support has been established. The efficiency of this end-to-end system was proved during the large under-sea earthquake of 8.4 M that occurred in September 12, 2007 in the Indian Ocean”

Citation of Disaster Mitigation Award to Mr. Amod Mani Dikshit

“Born in 1948 in Kathmandu Valley of Nepal, Mr. Amod Mani Dixit studied Geological & Mineralogical Sciences from the Leningrad Mining Institute, Russia and Geotechnical Engineering from the Asian Institute of Technology, Bangkok and earned Master’s Degree in both the disciplines. He started his professional career in 1973 with the Department of Mines & Geology, Government of Nepal which he served for 6 years before he joined a private engineering consulting firm as its Director. He founded the National Society for Earthquake Technology - Nepal in 1994 and is being working as its Executive Director since then.

Mr. Dikshit was driven by a firm conviction that scientific knowledge of geology, seismology and engineering should be demystified and a massive awareness built among all the stakeholders, particularly the vulnerable communities in the rural and the urban areas, to build a safe habitat that can withstand the hazards of nature. For this purpose he undertook a number of innovative projects for reducing the risks of disasters, many of these funded by bi-lateral and multi-lateral agencies. Some of these projects include the School Earthquake Safety Programme, Municipal Earthquake Risk Management Programme, Mason Training Programme, Shake Table Demonstration project, Programme for Enhancement of Emergency Response etc. Many of these programmes have been implemented in several countries of South and South East Asia. NSET today is one of the very few South Asian NGOs that have a global presence.

Mr. Amod Mani Dikshit has played a key role in the development of several policies and programmes on disaster management in Nepal, including the recently announced National Strategy for Disaster Risk Management. It was largely due to his initiative that January 16 is observed as the Earthquake Safety Day in Nepal to commemorate the devastating earthquake of 1934. His contribution for several global initiatives on earthquake risk management has been widely acknowledged.