Disaster Notes Imp

8/10/2019 Disaster Notes Imp

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Unit-1

A disasteris anatural orman-made (or technological)hazard resulting in an event of substantial

extent causing significant physical damage or destruction, loss of life, or drastic change to

theenvironment.A disaster can beostensively defined as any tragic event stemming from events such

asearthquakes,floods,catastrophicaccidents,fires,orexplosions.It is a phenomenon that can causedamage to life and property and destroy the economic, social and cultural life of people.

In contemporary academia, disasters are seen as the consequence of inappropriatelymanaged risk.

These risks are the product of a combination of both hazard/s and vulnerability. Hazards that strike in

areas with low vulnerability will never become disasters, as is the case in uninhabited regions.

Developing countries suffer the greatest costs when a disaster hitsmore than 95 percent of all deaths

caused by disasters occur in developing countries, and losses due to natural disasters are 20 times

greater (as a percentage ofGDP)in developing countries than in industrialized countries.

Types-

Natural hazardsare naturally occurring physical phenomena caused either by rapid or slow onsetevents which can be geophysical(earthquakes,landslides,tsunamis andvolcanicactivity), hydrological(avalanches andfloods), climatological (extreme temperatures,droughtandwildfires), meteorological (cyclones andstorms/wave surges)or biological(diseaseepidemics andinsect/animal plagues).Technological or man-made hazards(complex emergencies/conflicts,famine,displacedpopulations,industrial accidents andtransport accidents)are events that are caused by humansandoccur in or close to human settlements. This can include environmental degradation, pollution andaccidents. Technological or man-made hazards (complex emergencies/conflicts, famine, displacedpopulations, industrial accidents and transport accidents)There are a range of challenges, such asclimate change,unplanned-urbanization,under-development/poverty as well as the threat ofpandemics,that will shape humanitarian assistance in thefuture. These aggravating factorswill result in increased frequency, complexity and severity ofdisasters.

Or

A natural disasteris a majoradverse event resulting fromnatural processes of the Earth; examplesincludefloods,volcanic eruptions,earthquakes,tsunamis,and other geologic processes. A naturaldisaster can cause loss of life or property damage, and typically leaves some economic damage in itswake, the severity of which depends on the affected population'sresilience,or ability to recover

Natural Types of Disasters

Agricultural diseases & pests Damaging Winds

Drought and water shortage

Earthquakes

Emergency diseases

(pandemic influenza)

Extreme heat

Floods and flash floods

Hail

Hurricanes and tropical storms

Landslides & debris flow

Thunderstorms andlighting

Tornadoes

Tsunamis

Wildfire

Winter and ice storms

Sinkholes

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Hurricanes and tropical storms are among the most powerful natural disasters because of their size

and destructive potential. Tornadoes are relatively brief but violent, potentially causing winds in

excess of 200 mph. Both earthquakes and tornadoes strike suddenly without warning.

Flooding is the most common of natural hazards, and requires an understanding of the natural systemsof our environment, including floodplains and the frequency of flooding events. Wildfires are more

prevalent in the event of a drought. Disasters impacting food supply can be extremely costly;

American officials say that a food contamination scare similar to the one that hit the Belgian poultry

industry in the 1990s could jeopardize U.S. agricultural exports in excess of $140 billion.

Man-Made and Technological Types of Disasters

Hazardous materials

Power service disruption

&blackout Nuclear power plant andnuclear

blast

Radiological emergencies

Chemical threat andbiological

weapons Cyber attacks

Explosion

Civil unrest

Disasters also can be caused by humans. Hazardous materials emergencies include chemical spills and

groundwater contamination. Workplace fires are more common and can cause significant property

damage and loss of life. Communities are also vulnerable to threats posed by extremist groups who

use violence against both people and property.

High-risk targets include military and civilian government facilities, international airports, large cities

and high-profile landmarks. Cyber-terrorism involves attacks against computers and networks done to

intimidate or coerce a government or its people for political or social objective

Difference between disaster and hazard-

Natural hazards are things that take place in nature that cause harm. The word "natural" is used to notethat the disaster is caused by nature. Some examples of natural hazards are: earthquakes, hurricanes,

sinkholes, hail storms, wildfires, and the like. It might also be helpful to keep in mind that one naturalhazard can lead to another. For example, an earthquake can cause a tsunami.

Natural disasters are slightly different. They are the effects of natural hazards on humanity. Forexample, the tsunami in Indonesia caused a great amount of loss of property and more importantlylives. The earthquake and tsunami in Japan also caused loss of property and lives, as well as nuclearfallout.

Earthquakes, floods, tsunamis, wildfires, landslides, droughts, and volcanic eruptions are naturalhazards that cause a lot of destruction but they are termed as disasters when they occur in places thatare heavily inhabited areas. They are natural phenomenon that take place without regard to humansand do not strike a place taking into account built environment or the population. When any of these

hazards takes place in an area that is desolate, it causes no harm to human lives or property and henceis not called a disaster though technically it is the same phenomenon that would have raised an alarm
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had it taken place in an area that was thickly populated.

Tornados and typhoons occur frequently in many parts of the world but are labeled as disasters onlywhen they take place where there is built environment and human population. It is clear then that ahazard is an event that has the potential to cause widespread destruction and loss of lives andproperty. But when a hazard strikes an area that has no human population, though it still hasdestructive properties, it is not termed as a disaster.Apart from this difference, there are factors that are manmade and help in turning a hazard into adisaster. The way and the speed in which deforestation is taking place in many parts of the world hasresulted in an increased frequency of floods that lead to widespread destruction. Earthquakes inseismic zones that are prone to them cannot be prevented but high concentration of human populationand inadequately built houses that cannot withstand earthquakes lead to disasters at a very high levelresulting in loss of valuable lives.Hazards are natural phenomenon, they cannot be prevented. But we can certainly learn to live inharmony with nature by not taking steps that can turn hazards into major disasters. If one takes intoaccount the cost that we finally pay when a disaster strikes that the cost of averting it, we come to aconclusion that it is prudent to be prepared rather than inviting the wrath of nature on a very large

scale

or

Natural hazards are geographical events which occur naturally UNDER (earthquakes and

volcanoes), ON (floods) or ABOVE (climatic conditions such as droughts and tropical

cyclones) the surface of the earth. Things such as droughts, floods, tropical cyclones, volcanic

eruptions and volcanoes regularly happen on a small scale throughout the world. However, if

one of these natural hazards leads toa significant loss of human life and/ordamage to

property, and/orenvironmental damage,it is called a NATURAL DISASTER.

Disaster and crisis-

Disaster synonyms used by practitioners and experts have included calamity and catastrophe.

Similar words are emergency and crises. Disasters are abrupt shocks to the socio-economic and

environmental system, involving loss of life and property. The definition that is provided by the

UN/ISDR (United Nations International Strategy for Disaster Reduction) is one of the most

appropriate definitions: A disaster is a sudden, calamitousevent that causes serious disruption of the

functioning of a community or a society causing widespread human, material, economic and/or

environmental losses which exceed the ability of the affected community or society to cope using its

own level of resources.

Other sources define it as An unforeseen and often sudden event that causes great damage,

destruction and human suffering. Though often caused by nature, disasters can have human origins.;

The combination of hazards, vulnerability and inability to reduce the potential negative

consequences of risk results in disaster. etc.


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Crisis is is any event that is, or is expected to lead to, an unstable and dangerous situation affecting an

individual, group, community, or whole society. Crises are deemed to be negative changes in

thesecurity,economic,political,societal,orenvironmentalaffairs,especially when they occur

abruptly, with little or nowarning.More loosely, it is a term meaning 'a testing time' or an 'emergency

event'.

Crisis is the situation of a complex system(family, economy, society) when the system functions

poorly, an immediate decision is necessary, but the causes of the dysfunction are not known.

a) situation of a complex systemsimple systems do not enter crises. We can speak about a crisis of

moral values, an economical or political crisis, but not a motor crisis.

b) poor function. The system still functions, but does not break down.

c) an immediate decision is necessary to stop the further disintegration of the system.

d) the causes are so many, or unknown, that it is impossible to take a rational, informed decision to

reverse the situation.

Crisis has several defining characteristics. Seeger, Sellnow, and Ulmer[2]say that crises have four

defining characteristics that are "specific, unexpected, and non-routine events or series of events that

[create] high levels of uncertainty and threat or perceived threat to an organization's high priority

goals." Thus the first three characteristics are that the event is

1. unexpected (i.e., a surprise)

2. creates uncertainty

3. is seen as a threat to important goals

Venette[3]argues that "crisis is a process of transformation where the old system can no longer

be maintained." Therefore the fourth defining quality is the need for change. If change is not

needed, the event could more accurately be described as a failure.

Apart from natural crises that are inherently unpredictable (volcanic eruptions,

tsunami etc.) most of the crises that we face are created by man. Hence the

requirements of their being 'unexpected' depends upon man failing to note the onset

of crisis conditions. Some of our inability to recognise crises before they become

dangerous is due to denial and other psychological responses[4]that provide succour

and protection for our emotions.

Types of crisis-

Poverty-related crisis

Unemployment and underemployment

Not paying rent may lead tohomelessness throughforeclosure oreviction.Being unemployed, and

the financial difficulties and loss ofhealth insurancebenefits that come with it, may cause

malnutrition and illness, and are major sources ofself-esteem which may lead todepression,which

may have a further negative impact onhealth.

Lacking a job often means lacking social contact with fellow employees, a purpose for many hours of

the day, lack ofself-esteem,and mental stress.
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Economic crisis

An economic crisisis a sharp transition to arecession.See for example1994 economic crisis in

Mexico,Argentine economic crisis (19992002),South American economic crisis of

2002,Economic crisis of Cameroon.Crisis theory is a central achievement in the conclusions

ofKarl Marx's critique of Capital.

Afinancial crisis may be abanking crisis orcurrency crisis.

Environmental crisis

Crises pertaining to the environment include:

Environmental disaster

An environmental disasteris adisaster that is due to human activity and should not be confused

withnatural disasters (see below). In this case, the impact of humans' alteration of

theecosystem has led to widespread and/or long-lasting consequences. It can include the deaths of

animals (including humans) and plant systems, or severe disruption of human life, possibly

requiring migration.

Natural disaster

A natural disasteris the consequence of a naturalhazard(e.g.volcanic

eruption,earthquake,landslide)which moves from potential into an active phase, and as a result

affects human activities. Human vulnerability, exacerbated by the lack of planning or lack of

appropriateemergency management,leads to financial, structural, and human losses. The

resulting loss depends on the capacity of the population to support or resist the disaster, their

resilience.[7]

This understanding is concentrated in the formulation: "disasters occur when hazardsmeetvulnerability".[8]A natural hazard will hence never result in a natural disaster in areas

without vulnerability, e.g. strong earthquakes in uninhabited areas.

.

Endangered species

An endangered speciesis a population of an organism which is at risk of

becomingextinctbecause it is either few in number, or threatened by changing environmental or

predation parameters. An endangered species is usually a taxonomicspecies,but may be

anotherevolutionary significant unit.TheWorld Conservation Union (IUCN) has classified 38

percent of the 44,837 species assessed by 2008 as threatened.

[9]

International crisis

For information about crises in the field of study ininternational relations,seecrisis

management andinternational crisis.In this context, a crisis can be loosely defined as a situation

where there is a perception of threat, heightened anxiety, expectation of possible violence and the

belief that any actions will have far-reaching consequences (Lebow, 710).

Personal crisis

A personal crisis can occur when events of an extraordinary nature trigger extreme tension and

stress within an individual which require major decisions or actions to resolve. A crisis situationcan revolve around a dangerous situation such as extreme weather conditions or a medical
http://en.wikipedia.org/wiki/Recessionhttp://en.wikipedia.org/wiki/1994_economic_crisis_in_Mexicohttp://en.wikipedia.org/wiki/1994_economic_crisis_in_Mexicohttp://en.wikipedia.org/wiki/Argentine_economic_crisis_(1999%E2%80%932002)http://en.wikipedia.org/wiki/Argentine_economic_crisis_(1999%E2%80%932002)http://en.wikipedia.org/wiki/Argentine_economic_crisis_(1999%E2%80%932002)http://en.wikipedia.org/wiki/South_American_economic_crisis_of_2002http://en.wikipedia.org/wiki/South_American_economic_crisis_of_2002http://en.wikipedia.org/wiki/Economic_crisis_of_Cameroonhttp://en.wikipedia.org/wiki/Crisis_theoryhttp://en.wikipedia.org/wiki/Karl_Marxhttp://en.wikipedia.org/wiki/Financial_crisishttp://en.wikipedia.org/wiki/Banking_crisishttp://en.wikipedia.org/wiki/Currency_crisishttp://en.wikipedia.org/wiki/Disasterhttp://en.wikipedia.org/wiki/Natural_disasterhttp://en.wikipedia.org/wiki/Crisis#Natural_disasterhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Hazardhttp://en.wikipedia.org/wiki/Hazardhttp://en.wikipedia.org/wiki/Volcanic_eruptionhttp://en.wikipedia.org/wiki/Volcanic_eruptionhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Landslidehttp://en.wikipedia.org/wiki/Emergency_managementhttp://en.wikipedia.org/wiki/Crisis#cite_note-7http://en.wikipedia.org/wiki/Crisis#cite_note-7http://en.wikipedia.org/wiki/Crisis#cite_note-7http://en.wikipedia.org/wiki/Vulnerabilityhttp://en.wikipedia.org/wiki/Crisis#cite_note-8http://en.wikipedia.org/wiki/Crisis#cite_note-8http://en.wikipedia.org/wiki/Crisis#cite_note-8http://en.wikipedia.org/wiki/Extincthttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Evolutionary_significant_unithttp://en.wikipedia.org/wiki/World_Conservation_Unionhttp://en.wikipedia.org/wiki/Crisis#cite_note-IUCN-9http://en.wikipedia.org/wiki/Crisis#cite_note-IUCN-9http://en.wikipedia.org/wiki/Crisis#cite_note-IUCN-9http://en.wikipedia.org/wiki/International_relationshttp://en.wikipedia.org/wiki/Crisis_managementhttp://en.wikipedia.org/wiki/Crisis_managementhttp://en.wikipedia.org/wiki/International_crisishttp://en.wikipedia.org/wiki/International_crisishttp://en.wikipedia.org/wiki/Crisis_managementhttp://en.wikipedia.org/wiki/Crisis_managementhttp://en.wikipedia.org/wiki/International_relationshttp://en.wikipedia.org/wiki/Crisis#cite_note-IUCN-9http://en.wikipedia.org/wiki/World_Conservation_Unionhttp://en.wikipedia.org/wiki/Evolutionary_significant_unithttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Extincthttp://en.wikipedia.org/wiki/Crisis#cite_note-8http://en.wikipedia.org/wiki/Vulnerabilityhttp://en.wikipedia.org/wiki/Crisis#cite_note-7http://en.wikipedia.org/wiki/Emergency_managementhttp://en.wikipedia.org/wiki/Landslidehttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Volcanic_eruptionhttp://en.wikipedia.org/wiki/Volcanic_eruptionhttp://en.wikipedia.org/wiki/Hazardhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Crisis#Natural_disasterhttp://en.wikipedia.org/wiki/Natural_disasterhttp://en.wikipedia.org/wiki/Disasterhttp://en.wikipedia.org/wiki/Currency_crisishttp://en.wikipedia.org/wiki/Banking_crisishttp://en.wikipedia.org/wiki/Financial_crisishttp://en.wikipedia.org/wiki/Karl_Marxhttp://en.wikipedia.org/wiki/Crisis_theoryhttp://en.wikipedia.org/wiki/Economic_crisis_of_Cameroonhttp://en.wikipedia.org/wiki/South_American_economic_crisis_of_2002http://en.wikipedia.org/wiki/South_American_economic_crisis_of_2002http://en.wikipedia.org/wiki/Argentine_economic_crisis_(1999%E2%80%932002)http://en.wikipedia.org/wiki/1994_economic_crisis_in_Mexicohttp://en.wikipedia.org/wiki/1994_economic_crisis_in_Mexicohttp://en.wikipedia.org/wiki/Recession


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emergency or long-term illness. A crisis can also be related to a change in events that comprise

the day-to-day life of a person and those in their close circle. Such situations may be loss of a job;

extreme financial hardship; alcoholism or addiction and other situations that are life altering and

require action that is outside the "normal" daily routine.

Causers of different disasters-

The causes of natural disasters are many. Human activities play a role in the frequency and

severity of disasters. A natural disaster is a disruption in the balance of the environment. The

human factor raises the cost, in both property damage and loss of life. Understanding the causes

of natural disaster can provide clues to their prevention.

Floods

According to the U.S. Environmental Protection Agency (EPA), barring fire, floods are the mostcommon natural disaster affecting Americans. Floods are a factor in 90 percent of natural disasters.Flood events have both natural and man-made causes. Storm events can create flood waters thatexceed the capacity of the environment or man-made structures. Levees and dams provide a falsesense of security as became evident during the Great Flood of 1993 in the Upper Mississippi Rivervalley. A painful lesson was learned. Wetlands destruction removed a natural means to absorbfloodwaters.

Fires


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Prevention/Solution

Not all natural disasters can be prevented. Each natural disaster has its own factors and complications.Understanding the basic principles of ecology can provide keys to lessening their effects. Natureevolved with natural disasters and disturbance. The best prevention is looking at the strategies foundin nature.

impact-

1) Short-medium-term effects directly involving people and goods affected by a

disaster

The articles included in this group employ the simplest approach: the impact is expressed

by the list of damaged elements and neither monetary figures nor other assessment are

performed (Ngecu & Ichangi, 1999; Whitworth et al., 2006; Bilgehan & Kilic, 2008).

Frequently used impact indicators include numbers of victims and damage to buildings,

roads and agriculture. In these studies, damage data are obtained by state agencies or even

collected by directly asking people involved in the disaster. Both the number of victims and

the percentage of people affected are used to compare the impact of a disaster on various

communities (Msilimba, 2010) or that of disasters that have occurred in different time and

places. Some of these articles focus on damage to people, analysing the circumstances

leading to loss of life and assessing them in relation to vulnerability factors (e.g., age, race,

and gender) (Jonkman et al., 2009).

2) Medium- and long-term socio-economic effects


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In these articles, after individuating the affected population and the pre-disaster situation,

the researchers isolated effects on social sectors (the population, housing, health and

education), service infrastructure (drinking water and sewage, communications, electricity

and power), and production sectors (agriculture, industry and trade) in order to measure

the disaster's impact on the macroeconomic indicators during a period of one to two years

after the disaster (ECLAC, 1991).

Natural disasters are seen as a function of a specific natural process and economic activity

(Raschky, 2008). The indicators used to detect the impact on national economies include a)

long-term recovery businesses (Webb et al., 2002); b) changes in flow variables such as

annual agricultural output (Patwardhan & Sharma, 2005); c) variations in fiscal pressure

(Noy & Nualsri, 2011); and d) effects on the labour market (Belasen & Polachek, 2007;

Zissimopoulos & Karoly, 2010).

3) The impact of Damaging Hydro-geological Events (DHEs)

This paragraph focuses on climate-related damaging phenomena as landslides, floods,

urban flooding, and storm surges which occur during periods of bad weather conditions,

lasting from one to a few days, and characterised by intense rainfall and sometimes strong

winds. These periods can be defined as Damaging Hydro-geological Events (DHEs)

(Petrucci & Polemio 2003, 2009), and their impact can be assessed as the sum of the damage

caused by all the damaging phenomena triggered through a selected DHE.

unit-2

epidemic-

Natural disasters that do not result in population displacement, regardless of type of

disaster, are rarely associated with increased risk for epidemics. However, large-scale

population displacement, with consequent overcrowding in temporary settlements and

disruption of water supply and sanitation, are indeed associated with increased risks for

communicable disease transmission. This distinction is well documented . Increased

communicable disease incidence after flooding and cyclones has been particularly welldescribed . In addition, after a disaster of any type, epidemics may go undetected


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because of poor surveillance or because baseline surveillance data for diseases (such as

dengue fever or malaria) are unavailable.

Although we agree with the authors that media reports are often exaggerated and that

the risk for epidemics after certain types of natural disasters (e.g., volcanic eruption) is

low, we believe the findings are somewhat misleading. Post disaster communicable

disease incidence is related more closely to the characteristics of the displaced

population (size, health status, living conditions) than to the precipitating event.

Diarrhoeal epidemics are frequently reported following natural disasters in developing countries.

Floods are recurrent in many African countries, such as Mozambique, and usually lead to a

significant increase in diarrhoeal disease incidences.

Or

The term epidemic has been derived from two Greek words, "Epi" means "upon " and "Demos" means "people".

Thus, an epidemic of an infectious disease is the occurrence of a number of cases of a disease, known or

suspected to be of infectious origin, that is unusually large or unexpected for the given place or time. An

epidemic often evolves rapidly. A threatened (potential) epidemic is said to exist when the circumstances are

such that epidemic occurrence of a specific disease may reasonably be anticipated. This requires a susceptible

human population, the presence of a disease agent, and the presence of a mechanism or mode of large-scale

transmission (e.g., contaminated water supply, poor sanitation andvector population)The unusual occurrence

in a community or region of disease, specific health related behaviours. Some use the term "outbreak" for a

small, usually localized epidemic in the interest of minimizing public alarm, unless the number of cases is indeedvery large. This definition covers the usual epidemic diseases such as, measles, chickenpox, and cholera, which

are compressed in time, but also the modern "slow" epidemics of non-communicable diseases like diabetic, heart

attacks, and depression. Epidemics are Public Health emergencies.

When an epidemic extends beyond the confines of a wide area, typically a continent, and becomes a more

widespread problem, it is a pandemic.

Drought-

Droughtis an extended period when a region notes a deficiency in its water supply whether surface

or underground water. A drought can last for months or years, or may be declared after as few as 15days.

[1]Generally, this occurs when a region receives consistently below averageprecipitation.It can

have a substantial impact on theecosystemandagricultureof the affected region. Although droughts

can persist for several years, even a short, intense drought can cause significant damage[2]

and harm

to the localeconomy.[3]

Prolonged drought has caused causemass migrationsand humanitarian

crises.

Many plant species, such ascacti,have adaptations such as reduced leaf area and waxy cuticles to

enhance their ability to tolerate drought. Some others survive dry periods as buried seeds. Semi-

permanent drought produces arid biomes such as deserts and grasslands.[4]

Most arid ecosystems

have inherently low productivity.
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Consequences[edit]

AMongolian gazelledead due to drought.

Periods of droughts can have significant environmental, agricultural, health, economic and social

consequences. The effect varies according to vulnerability. For example, subsistence farmers are

more likely to migrate during drought because they do not have alternative food sources. Areas with

populations that depend on as a major food source are more vulnerable to famine.

Drought can also reduce water quality, because lower water flows reduce dilution of pollutants and

increasecontaminationof remaining water sources. Common consequences of drought include:

Diminishedcrop growth or yield productionsand carrying capacity forlivestock

Dust bowls,themselves a sign oferosion,which further erode thelandscape

Dust storms,when drought hits an area suffering from desertification anderosion

Faminedue to lack of water forirrigation

Habitatdamage, affecting bothterrestrialandaquaticwildlife

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

Malnutrition,dehydrationand related diseases

Mass migration,resulting ininternal displacementand internationalrefugees

Reducedelectricity productiondue to reduced water flow throughhydroelectricdams

Shortages of water forindustrialusers

Snakemigration, which results in snakebites

Socialunrest

Warover natural resources, including water and food

Wildfires,such asAustralianbushfires,are more common during times of drought and even

death of people.

Types-

1) Meteorological droughtis defined usually on the basis of the degree of dryness (in

comparison to some normal or average amount) and the duration of the dry period.Definitions of meteorological drought must be considered as region specific since the
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atmospheric conditions that result in deficiencies of precipitation are highly variable fromregion to region.

2) Agricultural DroughtAgricultural drought links various characteristics of meteorological (or hydrological) drought to

agricultural impacts, focusing on precipitation shortages, differences between actual and

potential evapo transpiration, soil water deficits, reduced groundwater or reservoir levels, and

so forth. Plant water demand depends on prevailing weather conditions, biological

characteristics of the specific plant, its stage of growth, and the physical and biological

properties of the soil. A good definition of agricultural drought should be able to account for

the variable susceptibility of crops during different stages of crop development, from

emergence to maturity. Deficient topsoil moisture at planting may hinder germination, leading

to low plant populations per hectare and a reduction of final yield.

3) Hydrological DroughtHydrological drought is associated with the effects of periods of precipitation (including

snowfall) shortfalls on surface or subsurface water supply (i.e., stream flow, reservoir andlake levels, groundwater). The frequency and severity of hydrological drought is often defined

on a watershed or river basin scale. Although all droughts originate with a deficiency of

precipitation, hydrologists are more concerned with how this deficiency plays out through the

hydrologic system. Hydrological droughts are usually out of phase with or lag the occurrence

of meteorological and agricultural droughts. It takes longer for precipitation deficiencies to

show up in components of the hydrological system such as soil moisture, stream flow, and

groundwater and reservoir levels. As a result, these impacts are out of phase with impacts in

other economic sectors. For example, a precipitation deficiency may result in a rapid depletion

of soil moisture that is almost immediately discernible to agriculturalists, but the impact of

this deficiency on reservoir levels may not affect hydroelectric power production or

recreational uses for many months. Also, water in hydrologic storage systems (e.g.,reservoirs, rivers) is often used for multiple and competing purposes .

4) Socioeconomic DroughtSocioeconomic definitions of drought associate the supply and demand of some economic

good with elements of meteorological, hydrological, and agricultural drought. It differs from

the aforementioned types of drought because its occurrence depends on the time and space

processes of supply and demand to identify or classify droughts. The supply of many

economic goods, such as water, forage, food grains, fish, and hydroelectric power, depends

on weather. Because of the natural variability of climate, water supply is ample in some years

but unable to meet human and environmental needs in other years. Socioeconomic drought

occurs when the demand for an economic good exceeds supply as a result of a weather-

related shortfall in water supply. For example, in Uruguay in 198889, drought resulted in

significantly reduced hydroelectric power production because power plants were dependent on

streamflow rather than storage for power generation. Reducing hydroelectric power

production required the government to convert to more expensive (imported) petroleum and

implement stringent energy conservation measures to meet the nations power needs.

Or

DEFINITION OF DROUGHT

Drought is a weather-related natural disaster. It affects vast regions formonths or years. It has an impact on food production and it reduces life


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expectancy and the economic performance of large regions or entirecountries.

Drought is a recurrent feature of the climate. It occurs in virtually allclimatic zones, and its characteristics vary significantly among regions.

Drought differs from aridity in that drought is temporary; aridity is apermanent characteristic of regions with low rainfall.

Drought is an insidious hazard of nature. It is related to a deficiency ofprecipitation over an extended period of time, usually for a season ormore. This deficiency results in a water shortage for some activity, group,or environmental sector. Drought is also related to the timing of

precipitation. Other climatic factors such as high temperature, high wind,and low relative humidity are often associated with drought.

Drought is more than a physical phenomenon or natural event. Its impactresults from the relation between a natural event and demands on the watersupply, and it is often exacerbated by human activities. The experiencefrom droughts has underscored the vulnerability of human societies to thisnatural hazard.

Drought definitions are of two types: (1) conceptual, and (2) operational.Conceptual definitions help understand the meaning of drought and itseffects. For example, drought is a protracted period of deficient

precipitation which causes extensive damage to crops, resulting in loss ofyield.

Landslide-

A landslide, also known as a landslip, is ageological phenomenonwhich includes a wide

range of ground movements, such asrockfalls,deep failure ofslopesand

shallowdebrisflows, which can occur in offshore, coastal and onshore environments.

Although the action ofgravityis the primary driving force for a landslide to occur, there are

other contributing factors affecting the originalslope stability.Typically, pre-conditional factors

build up specific sub-surface conditions that make the area/slope prone to failure, whereas

the actual landslide often requires a trigger before being released.

Causes

Landslides occur when the stability of the slope changes from a stable to an unstable condition. A

change in the stability of a slope can be caused by a number of factors, acting together or alone.

Natural causes of landslides include:

groundwater(pore water) pressure acting to destabilize the slope

Loss or absence of vertical vegetative structure, soil nutrients, andsoil structure(e.g. after a

wildfire - a fire in forests lasting for 34 days)

erosionof the toe of a slope by rivers or oceanwaves
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weakening of a slope through saturation by snow melt,glaciersmelting, or heavy rains

earthquakesadding loads to barely stable slope

earthquake-causedliquefactiondestabilizingslopes

volcanic eruptions

Landslides are aggravated by human activities, such as

deforestation,cultivationandconstruction,which destabilize the already fragile slopes.

vibrationsfrommachineryortraffic

blasting

earthworkwhich alters the shape of a slope, or which imposes new loads on an existing slope

in shallowsoils,the removal of deep-rootedvegetationthat bindscolluviumtobedrock

Construction,agricultural or forestry activities (logging)which change the amount of water which

infiltrates the soil.

Types-

Debris flow

Slope material that becomessaturatedwith water may develop into adebris flowormud flow.The

resulting slurry ofrockand mud may pick up trees, houses and cars, thus blocking bridges

andtributariescausingfloodingalong its path.

Debris flow is often mistaken forflash flood,but they are entirely different processes.

Earthflows

Earthflowsare downslope, viscous flows of saturated, fine-grained materials, which move at any

speed from slow to fast. Typically, they can move at speeds from 0.17 to 20 km/h. Though these are a

lot likemudflows,overall they are slower moving and are covered with solid material carried along by

flow from within. They are different from fluid flows in that they are more rapid. Clay, fine sand and silt,

and fine-grained, pyroclastic material are all susceptible to earthflows. The velocity of the earthflow is

all dependent on how much water content is in the flow itself: if there is more water content in the

flow, the higher the velocity will be.

Debris landslide

A debris slide is a type of slide characterized by the chaotic movement of rocks soil and debris mixed

with water or ice (or both). They are usually triggered by the saturation of thickly vegetated slopes

which results in an incoherent mixture of broken timber, smaller vegetation and other debris.[2]

Debris

avalanches differ from debris slides because their movement is much more rapid. This is usually a

result of lower cohesion or higher water content and commonly steeper slopes.

Shallow landslide

shallow landslides can often happen in areas that have slopes with high permeable soils on top of lowpermeable bottom soils. The low permeable, bottom soils trap the water in the shallower, high
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permeable soils creating high water pressure in the top soils. As the top soils are filled with water and

become heavy, slopes can become very unstable and slide over the low permeable bottom soils. Say

there is a slope with silt and sand as its top soil and bedrock as its bottom soil

Deep-seated landslide

Landslides in which the sliding surface is mostly deeply located below the maximum rooting depth of

trees (typically to depths greater than ten meters). Deep-seated landslides usually involve

deepregolith,weathered rock, and/orbedrockand include large slope failure associated with

translational, rotational, or complex movement. These typically move slowly, only several meters per

year, but occasionally move faster. They tend to be larger than shallow landslides and form along a

plane of weakness such as afaultorbedding plane.They can be visually identified by

concavescarpsat the top and steep areas at the toe.

Forest fire-

A forest fire is an uncontrolled fire occurring in nature. Sometimes, the forest fire is so large

that it takes a long time for the fire fighting crews to gain control over the situation. This could

result in massive destruction.

Volcano and earthquakes-

Volcanic Earthquakes
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Earthquakes related to volcanic activity may produce hazards which

include ground cracks, ground deformation, and damage to

manmade structures. There are two general categories of

earthquakes that can occur at a volcano: volcano-tectonic

earthquakes and long period earthquakes.

Earthquakes produced by stress changes in solid rock due to the

injection or withdrawal of magma(molton rock) are called volcano-

tectonic earthquakes(Chouet, 1993). These earthquakes can cause

land to subside and can produce large ground cracks. These

earthquakes can occur as rock is moving to fill in spaces where

magma is no longer present. Volcano-tectonic earthquakes don't

indicate that the volcano will be erupting but can occur at anytime.

The second category of volcanic earthquakes are long periodearthquakeswhich are produced by the injection of magma into

surrounding rock. These earthquakes are a result of pressure

changes during the unsteady transport of the magma. When magma

injection is sustained a lot of earthquakes are produced (Chouet,

1993). This type of activity indicates that a volcano is about to erupt.

Scientists use seismographs to record the signal from these

earthquakes. This signal is known as volcanic tremor.

People living near an erupting volcano are very aware of volcanicearthquakes. Their houses will shake and windows rattle from the

numerous earthquakes that occur each day before and during a

volcanic eruption. Residents in Pompeii felt earthquakes daily before

Vesuvius erupted in A.D. 79 but continued to go about their daily

routines (Francis, 1993). When Mount Pinatubo in the Philipines

erupted in 1991, nerves were rattled as much as windows by

volcanic earthquakes.


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Earthquakes exhibiting volcanic tremor warn of an impending

eruption so that people can be evacuated to areas of safety. The

volcanic tremor signal has been used successfully to predict the

1980 eruptions Mount St. Helens and the 1991 eruption of Pinatubo.

Volcano-tectonic earthquakes can cause damage to manmade

structures and landsliding. To prevent damage from being done,

structures should be built according to earthquake standards,

building foundations should be constructed on firm ground and not

unconsolidated material which may amplify earthquake intensity,

and buildings should be constructed on stable slopes in areas of low

hazard potential.

Tsunami-

A tsunami(plural: tsunamis or tsunami English pronunciation: is a series of water waves caused by

the displacement of a large volume of a body of water, generally an ocean or alarge

lake.Earthquakes,volcanic eruptionsand otherunderwater explosions(including detonations of

underwaternuclear devices), landslides,glacier calvings,meteorite impactsand other disturbances

above or below water all have the potential to generate a tsunami.[3]

Tsunami waves do not resemble normalsea waves,because their wavelength is far longer. Rather

than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly risingtide,and

for this reason they are often referred to as tidal waves. Tsunamis generally consist of a series of

waves withperiodsranging from minutes to hours, arriving in a so-called "wave train".[4]Wave heights

of tens of metres can be generated by large events. Although the impact of tsunamis is limited to

coastal areas, their destructive power can be enormous and they can affect entire ocean basins;

the2004 Indian Ocean tsunamiwas among the deadliest natural disasters in human history with over

230,000 people killed in 14 countries bordering theIndian Ocean.

Tsunami are sometimes referred to as tidal waves, which are unusually high sea waves that are

triggered especially by earthquakes. In recent years, this term has fallen out of favor, especially in the

scientific community, because tsunami actually have nothing to do with tides.The once-popular term

derives from their most common appearance, which is that of an extraordinarily hightidal bore.

Tsunami and tides both produce waves of water that move inland, but in the case of tsunami the

inland movement of water is much greater and lasts for a longer period, giving the impression of an

incredibly high tide. Although the meanings of "tidal" include "resembling"or "having the form or

character of"the tides, and the term tsunamiis no more accurate because tsunami are not limited to

harbours, use of the term tidal waveis discouraged bygeologistsandoceanographers.

Unit-3

Ecological disaster- An environmental disasteris adisasterto thenatural environmentdue to

human activity,[1]

which distinguishes it from the concept of anatural disaster.It is also distinct from

intentional acts of war such as nuclear bombings.
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In this case, the impact of humans' alteration of theecosystemhas led to widespread and/or long-

lasting consequences. It can include the deaths of animals (including humans) and plants, or severe

disruption of human life, possibly requiring migration.

Deforestation, clearanceor clearingis the removal of a forest or stand of trees where the land is

thereafter converted to a non-forest use. Examples of deforestation include conversion of forestlandto farms, ranches, or urban use.

The term deforestationis often misused to describe any activity where all trees in an area are

removed. However intemperate climates,theremoval of all trees in an areain conformance

withsustainable forestrypracticesis correctly described as regeneration harvest. Intemperate

mesic climates,natural regeneration of forest stands often will not occur in the absence of

disturbance, whether natural or anthropogenic. Furthermore, biodiversity after regeneration harvest

often mimics that found after natural disturbance, including biodiversity loss after naturally occurring

rainforest destruction.

Deforestation occurs for many reasons: trees are cut down to be used or sold as fuel (sometimes in

the form ofcharcoal)or timber, while cleared land is used aspasturefor livestock, plantations of

commodities and settlements. The removal of trees without sufficientreforestationhas resulted in

damage tohabitat,biodiversityloss andaridity.It has adverse impacts onbio equestrationof

atmosphericcarbon dioxide.

Erosionis the process by which soil and rock are removed from the Earth's surface by exogenic

processes such as wind or water flow, and thentransportedanddepositedin other locations.

While erosion is a natural process, human activities have increased by 10-40 times the rate at which

erosion is occurring globally. Excessive erosion causes problems such asdesertification,decreases

in agricultural productivity due to land degradation,sedimentationof waterways, andecological

collapsedue to loss of the nutrient rich uppersoil layers.Water and wind erosion are now the two

primary causes ofland degradation;combined, they are responsible for 84% of degraded acreage,

making excessive erosion one of the most significant global environmental problems

Soil erosionis the washing or blowing away (by wind or water) of the top layer ofsoil(dirt).

This is a serious problem for people who want to growcrops.Crops are the foods thatfarmersgrow.

If the soil has eroded, the crops will not grow very well.

Soil erosion can be prevented several ways.

Planting wind breaks can be effective. A wind break is a line of plants that are planted to stop or

slow the wind. A thick row of bushes planted next to a field of plants can stop the wind from

blowing the soil away. This method also helps against water erosion, as the soil gets caught up

against the roots of the bushes, rather than washing away.

Terracingcan also be effective. Terraces are level places that have been made by people on hill

sides. People can cut level sides into the side of hills to create a place to grow crops.

If the crops are growing on a slope, then one should plant them in lines that run across, the slope,

rather than up and down. So, if the slope goes downhill to the south, then the plants should be in

rows that run from east to west.
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To prevent decomposition the government can put up groynes (wooden planks) along the

beaches, or they could buildsea wallsagainst the cliffs.

Soil erosion is a natural process. It becomes a problem when human activity

causes it to occur much faster than under natural conditions.

CAUSES OF SOIL EROSIONWind and water are the main agents of soil erosion. The amount of soil they can carry awayis influenced by two related factors:

* speed - the faster either moves, the more soil it can erode;

* plant cover - plants protect the soil and in their absence wind and water can do much moredamage.

Air pollution-

Air pollutionis the introduction ofchemicals,particulates,biological materials,or other harmful

materials into theEarth's atmosphere,possibly causing disease, death to humans, damage to other

living organisms such as food crops, or thenaturalorbuilt environment.

The atmosphere is a complex natural gaseous system that is essential to support life on

planetEarth.Stratosphericozone depletiondue to air pollution has long been recognized as a threat

to human health as well as to the Earth'secosystems.

Water pollutionis the contamination ofwaterbodies

(e.g.lakes,rivers,oceans,aquifersandgroundwater). Water pollution occurs whenpollutantsare

directly or indirectly discharged into water bodies without adequatetreatmentto remove harmful

compounds.

Water pollution affects plants and organisms living in thesebodies of water.In almost all cases the

effect is damaging not only to individualspeciesand populations, but also to the naturalbiological

communities.

Water pollution is a major global problem which requires ongoing evaluation and revision ofwater

resource policyat all levels (international down to individual aquifers and wells). It has been

suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the

deaths of more than 14,000 people daily. An estimated of 580 people in India die of water pollution

related illness every day. Some 90% ofChina's cities suffer fromsome degree of water pollution,and

nearly 500 million people lack access to safe drinking water. In addition to the acute problems of

water pollution indeveloping countries,developed countriescontinue to struggle with pollution

problems as well. In the most recent national report onwater qualityin the United States, 45 percent

of assessed stream miles, 47% of assessed lake acres, and 32 percent of

assessedbaysandestuarinesquare miles were classified as polluted.

Water is typically referred to as polluted when it is impaired byanthropogeniccontaminants and either

does not support a human use, such asdrinking water,or undergoes a marked shift in its ability to

support its constituent biotic communities, such as fish. Natural phenomena such asvolcanoes,algae

blooms,storms, and earthquakes also cause major changes in water quality and the ecological status

of water.
http://simple.wikipedia.org/wiki/Sea_wallhttp://simple.wikipedia.org/wiki/Sea_wallhttp://simple.wikipedia.org/wiki/Sea_wallhttp://en.wikipedia.org/wiki/Chemicalhttp://en.wikipedia.org/wiki/Chemicalhttp://en.wikipedia.org/wiki/Chemicalhttp://en.wikipedia.org/wiki/Particulateshttp://en.wikipedia.org/wiki/Particulateshttp://en.wikipedia.org/wiki/Particulateshttp://en.wikipedia.org/wiki/Biomoleculehttp://en.wikipedia.org/wiki/Biomoleculehttp://en.wikipedia.org/wiki/Biomoleculehttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Natural_environmenthttp://en.wikipedia.org/wiki/Natural_environmenthttp://en.wikipedia.org/wiki/Natural_environmenthttp://en.wikipedia.org/wiki/Built_environmenthttp://en.wikipedia.org/wiki/Built_environmenthttp://en.wikipedia.org/wiki/Built_environmenthttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Stratospherehttp://en.wikipedia.org/wiki/Stratospherehttp://en.wikipedia.org/wiki/Ozone_depletionhttp://en.wikipedia.org/wiki/Ozone_depletionhttp://en.wikipedia.org/wiki/Ozone_depletionhttp://en.wikipedia.org/wiki/Ecosystemshttp://en.wikipedia.org/wiki/Ecosystemshttp://en.wikipedia.org/wiki/Ecosystemshttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Lakehttp://en.wikipedia.org/wiki/Lakehttp://en.wikipedia.org/wiki/Lakehttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Marine_pollutionhttp://en.wikipedia.org/wiki/Marine_pollutionhttp://en.wikipedia.org/wiki/Marine_pollutionhttp://en.wikipedia.org/wiki/Aquiferhttp://en.wikipedia.org/wiki/Aquiferhttp://en.wikipedia.org/wiki/Aquiferhttp://en.wikipedia.org/wiki/Groundwaterhttp://en.wikipedia.org/wiki/Groundwaterhttp://en.wikipedia.org/wiki/Groundwaterhttp://en.wikipedia.org/wiki/Pollutanthttp://en.wikipedia.org/wiki/Pollutanthttp://en.wikipedia.org/wiki/Pollutanthttp://en.wikipedia.org/wiki/Water_treatmenthttp://en.wikipedia.org/wiki/Water_treatmenthttp://en.wikipedia.org/wiki/Water_treatmenthttp://en.wikipedia.org/wiki/Bodies_of_waterhttp://en.wikipedia.org/wiki/Bodies_of_waterhttp://en.wikipedia.org/wiki/Bodies_of_waterhttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Biocoenosishttp://en.wikipedia.org/wiki/Biocoenosishttp://en.wikipedia.org/wiki/Biocoenosishttp://en.wikipedia.org/wiki/Biocoenosishttp://en.wikipedia.org/wiki/Water_resource_policyhttp://en.wikipedia.org/wiki/Water_resource_policyhttp://en.wikipedia.org/wiki/Water_resource_policyhttp://en.wikipedia.org/wiki/Water_resource_policyhttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/Water_pollution_in_Chinahttp://en.wikipedia.org/wiki/Water_pollution_in_Chinahttp://en.wikipedia.org/wiki/Water_pollution_in_Chinahttp://en.wikipedia.org/wiki/Developing_countryhttp://en.wikipedia.org/wiki/Developing_countryhttp://en.wikipedia.org/wiki/Developing_countryhttp://en.wikipedia.org/wiki/Developed_countrieshttp://en.wikipedia.org/wiki/Developed_countrieshttp://en.wikipedia.org/wiki/Developed_countrieshttp://en.wikipedia.org/wiki/Water_qualityhttp://en.wikipedia.org/wiki/Water_qualityhttp://en.wikipedia.org/wiki/Water_qualityhttp://en.wikipedia.org/wiki/Bayshttp://en.wikipedia.org/wiki/Bayshttp://en.wikipedia.org/wiki/Bayshttp://en.wikipedia.org/wiki/Estuaryhttp://en.wikipedia.org/wiki/Estuaryhttp://en.wikipedia.org/wiki/Estuaryhttp://en.wikipedia.org/wiki/Human_impact_on_the_environmenthttp://en.wikipedia.org/wiki/Human_impact_on_the_environmenthttp://en.wikipedia.or

Documents

Disaster Notes Imp