Hazard

Hazard

According to the United Nations International Strategy for Disaster Reduction (UNISDR), a hazard is a natural process or phenomenon that may pose negative impacts on the economy, society, and ecology. It includes both natural factors and associated human factors.

A hazard can be defined as a potentially damaging physical event, social and economic disruption or environmental degradation. Hazards can be the creation of man or the environment. 

A hazard is always present and it simply acts as a catalyst to bring adverse effects into focus. A hazard is defined as a potential cause which is activated when the right configuration of factors present themselves. A hazard may or may not lead to an event. 

A hazard is defines as “a potentially damaging physical event, phenomenon or human activity that may cause the loss of life or injury, property damage, social and economic disruption or environmental degradation.” Hazards could be, natural (geological, hydro-meteorological and biological) or induced by human processes (environmental degradation and technological hazards).

Hazards can be single, sequential or combined in their origin and effects. Hence, Hazard analysis entails the identification, study and monitoring of a hazard to determine its potential, origin and characteristics. 

Hazards are generally classified as:

• Sudden onset hazards: geological and climatic hazards such as earthquakes, tsunamis, floods, tropical storms, volcanic eruptions, and landslides.
• Slow onset hazards: (environmental hazards) drought, famine, environmental degradation, desertification, deforestation, and pest infestation.
• Industrial/Technological: system failures/accidents, spillages, explosions, and fires.
• Wars and civil strife: armed aggression, insurgency, terrorism, and other actions leading to  displaced persons and refugees.
• Epidemics: water and/or food-born diseases, person-to-person diseases (contact and respiratory spread), vector-born diseases and complications from wounds.

Hazards could also be classified as direct and indirect. 

Examples of "Direct Hazards" include:

• Ground shaking
• Differential ground settlement
• Soil liquefaction
• Immediate landslides or mud slides, ground lurching and avalanches
• Permanent ground displacement along faults
• Floods from tidal waves, sea surges & tsunamis

Examples of "Indirect hazards" include:

• Dam failures
• Pollution from damage to industrial plants
• Delayed landslides.

Site risks in an earthquake prone area include:

• Slope risks
• Natural dams (formed by landslides in irregular topographic areas and are susceptible to collapse when filled leading to catastrophic avalanches after strong seismic shaking)
• Volcanic activity

Hazards can also be classified as long-term of short-term as per the classification proposed by K. Smith

Identification of hazards involves analyses of scientific data to trace the causal path of

events leading to a disaster.

QUIZ - 2

QUIZ - 2

1. List the important human factors that influence disaster severity
2. How are disasters a precursor to scientific advancements leading to development
3. List the factors affecting vulnerability to disasters
4. List the impact of disasters on dams and embankments
5. Define "climate change adaptation" and list a few examples of the same
6. Define "indigenous knowledge"
7. List a few appropriate technologies used in disaster management
8. Define Disaster Risk Management
9. List the components of disaster relief
10. What is disaster management policy
11. List few policies related to disaster management
12. List policies related to disaster management other than disaster management act 2005 and disaster management policy
13. List the priority themes of the sendai framework
14. List the programs related to disaster management
    

HW-Qs

ASSIGNMENT QUESTIONS

Assignment 1 (HW#01, HW#02 & HW#03)

HW# 01

Q1. Write about natural vs man made disasters with examples

Q2. Explain the classification of droughts

HW# 02

Q1. Give a detailed classification of disasters

Q2. Write about heat waves and cold waves

HW# 03

Q1. Write about culture of safety

Q2. Write briefly about the roles and responsibilities of Panchayati Raj Institutions (PRIs) and Urban Local Bodies (ULBs) in disaster management

Assignment 2 (HW#04 & HW#05)
HW#04

Q1.Briefly describe the interrelationship between disasters and development
Q2.What are the various factors affecting vulnerability to disasters

HW#05

Q1. Briefly explain the vulnerability profile of India
Q2.Briefly explain the institutional arrangements with respect to disaster risk management in India

Impacts of disasters

IMPACTS OF DISASTERS

The primary impact of disasters is destruction of the environment. Environment encompasses the physical environment with all the natural sources and the living environment covering all the plants, animals and microorganisms. The social, economic, political, environmental, human health and psychosocial impacts of disasters are discussed below.

SOCIAL IMPACTS OF DISASTERS

Disasters can be extremely stressful, disruptive and traumatic for the affected people in a community. Social impacts of disasters is reflected in people experiencing increased mental health issues, alcohol misuse, domestic violence, chronic diseases, unemployment, family violence and environmental damage. Disasters entail social costs larger than direct financial impacts. Social impacts of disasters can be unbelievably stressful, disruptive and traumatic for the affected people. Entire communities can be uprooted, friends and family divided along with loss of homes, livelihoods and lives. People may experience shock and disbelief, fear and apprehension, anger, shame and guilt in the early days after a disastrous event. The cocial impacts of disasters can be summarized as:

• Changes in individual's role
• Disruption of social fabric
• Isolation
• Change in marital status
• Sexual abuse and domestic violence
• Orphans
• Single parent children
• Family and social disorganization
• Migration
• Lifestyle changes
• Breakdown of traditional social status

 ECONOMIC IMPACTS OF DISASTERS

On the surface, natural disasters cause serious damage and appear to be bad for the economy. They destroy tangible assets as well as the human capital. Sometimes, the damage is severe enough to cause closure of companies and manufacturing facilities. However, the academic evidence concerning the economic impacts of disasters is mixed. Certain studies report that natural disasters may promote growth. This is because of improvement of productivity of the corporate sector of the economy due to updation of capital stock coupled with adoption of new technologies. This is called 'creative destruction'. If natural disasters expel inefficient firms (following the law of natural selection), the average corporate productivity increases.
In conclusion, the recovery of the economy after natural disasters is closely intertwined with policy measures taken and the underlying economic conditions.The economic impacts of disasters can be summarized as:

• Loss of life
• Unemployment
• Loss of livelihood
• Loss of property or land
• Loss of household articles
• Loss of Crops
• Loss of public infrastructure

 POLITICAL IMPACTS OF DISASTERS

Natural disasters generally affect an individuals political trust and satisfaction with the government. Past research has studied the impact of disasters on long-term political impact of government and its policies. This has been achieved by way of examining retrospective voting and changes in attitudes towards civic engagement. At times, the effects on political trust occur immediately after a natural disaster.
ENVIRONMENTAL IMPACTS OF DISASTERS

The environmental impacts of earthquakes are listed below:

• Collapsing buildings, property damage, loss of power, mudslides, floods, tsunamis, erosion, heavy flooding of inland areas, contaminated water supply, loss of habitat, toxic gases released into the environment, diseases, 
• Water resources may be contaminated with toxins or  be rendered unusable for human consumption
• Any disaster has an adverse impact on the local biodiversity and forestry
• There might be occurrences of landslides, avalanches and Glacial Lake Outburst Flood (GLOF)
• The built environment may be damaged to different extents at different locations
• The health, safety and well-being of human beings and live stock may be put to grave danger
• The groundwater resources are at a risk of being contaminated
• The disaster may damage the hydro-power projects

HEALTH IMPACTS OF DISASTERS
Any disaster natural or man-made invariably has an adverse effect on human health. Health impacts due to disasters may be broadly classified as:

• Physical injuries and
• Infectious diseases due to inhalation of contaminated (particulate matter or toxic gases) air or ingestion of contaminated (particulate matter or toxins or infectious worms/microorganisms/parasites) water
• Other hazardous situations (slippery terrain, etc)

PSYCHOSOCIAL IMPACTS OF DISASTERS

• Any disastrous event is beyond the scope of normal human experience causes traumatic stress
• More than 90% of the people affected by a disaster show untoward psychological effects
• The extent and severity of the event affect the likelihood of people suffering from  the effects of the disaster
• Some of the vulnerability factors include:
• Witnessing death
• Being trapped
• Stigmatization of victims
• Lack of availability of social support networks
• People may suffer from psychological and behavioural syndrome
• People may be affected with psychological disorders
• People may suffer from persistent insomnia, anxiety, PTSD and depression
• self-destructive coping skills that include excessive alcohol and substance use and excessive work
• Despair, panic, survival guilt
• Inappropriate anger or resentment
• Aggressive or assaultive behaviour
• Lack of regard for other's comfort or dignity 
• Being uncooperative, defiant, rigid when dealing with problems or responding to requests for help
• Unprofessional demeanor
• Recurrent conflicts
• Difficulty with authority
• Inability to ask for or receive help
• Irritability, moodiness, verbal abuse
• Isolation
• Physical deterioration
• Distress
• Flashback
• Intrusion/Avoidance
• Hatred/Revenge
• Dependence/Insecurity
• Grief/Withdrawal/Isolation
• Guilt feeling
• Hypervigilance
• Lack of trust
• Helplessness
• Hoplessness

Causes of disasters

CAUSES OF DISASTERS

The various disasters and their causes are discussed below:

• Earthquakes: An Earthquake is caused by the sudden release of slowly accumulating strain energy along a fault in the Earth's crust. Areas of surface or underground that can experience Earthquakes are known as fault zones.
• Volcano: A volcano is caused due to sudden displacement of lava beneath the Earth's crust. Volcanoes are generally found where tectonic plates are converging or diverging. Volcanoes can also form where there is stretching and thinning of the Earth's crust. Volcanoes are classified as active volcano, dormant volcano and extinct volcano
• Cyclones: When water vapourises, it absorbs heat from the surroundings. Water vapour rises up and cools-down. The cooling water vapour releases heat and warms the atmosphere around it. The warm air rises and causes a drop in pressure. Air moves from surrounding high-pressure area to central low-pressure area. This cycle is repeated leading to the formation of a very low pressure system surrounded by very high-speed winds leading to the formation of a cyclone
• Floods: Flood is a natural occurrence where normally dry land is submerged in water. Floods may occur due to overflow of rivers, lakes, streams, oceans, dam breakage, clogged drains, excessive rain or melting of snow.
• Landslides: A landslide refers to downward movement of large masses of rock, soil, mud and organic debris. Landslides are caused due to the influence of gravity acting on weakened material that make-up sloping area of land. The triggering events for a landslide are Earthquakes or heavy rainfall. Excessive water or deforestation are the primary triggers for landslides
• Unrest / Conflicts / Wars: Wars have been a major source of disasters since the beginning of civilization. A few of the major reasons for war have been over natural resources, wealth, politically motivated or religious or social identity. In wars no party emerges victorious, the only end with destruction of natural resources
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Classification of disasters

CLASSIFICATION OF DISASTERS

Disasters are classified (based on source or origin) into:

1. Natural disasters and
2. Man-made disasters

Natural disasters are further classified (based on the location of their occurrence) into:

1. Terrestrial disasters and
2. Extraterrestrial disasters

Terrestrial disasters are classified into:

1. Endogenic disasters (examples of this type are listed below)
1. Earthquakes
2. Volcanoes
2. Exogenic disasters (examples of this type are listed below)
1. Atmospheric disasters
1. Drought
2. Rainfall
3. Snowfall
4. Winds
5. Hailstorms
2. Hydrospheric disasters (examples of this type are listed below)
1. Wave currents
2. Tsunamis
3. Floods
3. Lithospheric disasters (examples of this type are listed below)
1. Landslides
2. Weathering
3. Erosion
4. Silting
5. Avalanches
3. Biotic disasters
1. Floral disasters
2. Faunal disasters
3. Anthropogenic disasters (Human induced)
1. Physical disasters
1. Earthquake
2. Landslide
3. Erosion
2. Chemical disasters
1. Release of toxic chemical
2. Nuclear explosion
3. Biological disasters
1. Eutrophication
2. Population explosion

• Endogenic disasters originate under the surface of the Earth
• Exogenic disasters take place at the Earth's surface and are very destructive
• Biotic disasters occur due to activities of living organisms (Plants, animals or human beings)

Natural and Man-made disasters

Natural and man-made disasters

• Disaster is a sudden calamitous event that brings great damage, loss and destruction. In case of natural disasters steps can be taken to minimize the effects. Man made disasters can be avoided by careful planning and applying prevention methods. 
• Natural disasters are the destructive forces of nature that have a severe impact on the environment. Examples of natural disasters are blizzards, cyclones, earthquakes, famines, floods, landslides, tornadoes, tsunamis, volcanoes, wildfires, bushfires, etc.
• Manmade disasters are the hazards caused by human activities leading to the loss of life and property as well as damage to the country's economy and productive capacity. Examples of this kind are environmental pollution, terrorism, destruction of property, widespread hunger, road and rail accidents, bomb explosion, chemical spills, industrial accidents, nuclear accidents caused by by complex anthropogenic interacrions.
• Disasters can be classified based on their causative factors:
• Natural disasters are caused by natural forces while man made disasters are caused by activities of human beings. 
• Both types of disasters have a major impact on the society. 
• Examples of man-made disasters are 
• leakage of toxic chemical (MIC - Methyl Iso Cyanide) from the UCIL plant in Bhopal, India. 
• The great London smog of 1952 is another example of man-made disaster. The main cause for this disaster was severe air pollution and it resulted in the death of more than 6000 people aside from respiratory problems.

Tropical cyclones and local storms

TROPICAL CYCLONES AND STORMS

TROPICAL CYCLONE: 

• Tropical cyclones are generated in tropical areas of the ocean near the equator
• The winds generated move around a central eye
• Wind direction is counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere
• They are low-pressure systems
• The low pressure calm centre of circulation is called the 'eye'
• The area around the eye with the fastest, most violent winds is called the 'eye wall'
• Bands of thunderstorms circulating outward from the eye are part of the evaporation-condensation cycle that feed the storm are called 'Rain Bands'

Stages of development of a tropical cyclone:

1. Tropical wave is a trough of low-pressure in the trade-wind easterlies
2. Tropical disturbance is a moving area of thunderstorms in the tropics that maintains its identity for twenty four hours or more
3. Tropical depression: is a tropical cyclone in which the maximum sustained surface winds is almost sixty kmph
4. Tropical storm is a tropical cyclone in which the maximum sustained surface wind speed is almost 120 kmph
5. A tropical cyclone has maximum sustained surface winds of almost 118 knph. It is also called a hurricane or typhoon in different parts of the world 

The three events essential for a cyclone to form are:

1. A continuing evaporation-condensation cycle of warm, humid ocean air
2. Patterns of wind characterized by converging winds at the surface and  strong uniform wind speeds at higher altitudes
3. A pressure gradient between the surface and high altitude

LOCAL STORMS:

1. Storms are a result of vertical circulation in the atmosphere
2. Heavier (cold ) air sinks and warm air (lighter) rises
3. Potential energy is converted to kinetic energy
4. Strong winds are intense when a thunderstorm is accompanied by heavy rain
5. Due to precipitation surrounding air cools down and is dragged down
6. Near ground level, the stream of air veers into a horizontal plane causing rain or hail stones into a sloping trajectory, sometimes at 45 degrees from the vertical
7. A local storm is produced by a cumulonimbus cloud and accompanied by lightening and thunder, usually with strong gusts wind, heavy rain and sometimes with hail

Destruction by Cyclones
The destruction caused by cyclones depends on its intensity, location and size. The effects of a cyclone can be divided into:

• Primary Hazards
• Secondary Hazards and
• Tertiary Hazards

Examples of primary hazards are:

1. Strong winds, heavy rains and storms
2. Abnormal rise in sea level at the coast
3. Submergence of low lying areas near the coast resulting in drowning  of humans, livestock, habitations, destroying vegetation and soil fertility
4. Very strong winds damage houses, trees and communication systems resulting in huge loss to life and property

Examples of secondary hazards are:

1. Floods, fire and freshwater flooding
2. Floods in rivers causing submergence of nearby inhabited areas
3. Erosion of valuable fertile agricultural land
4. Destruction of buildings
5. Strong winds in forest regions result in forest fires which spread the intensity of cyclonic winds

 Examples of tertiary hazards are:

1. Tertiary hazards include diseases caused due to stagnant water, water poisoning and increase in prices of goods and resources

 Sometimes all the hazards occur simultaneously because of which relief operations become difficult. . As the water level rises in the streets, transportation, communication, rescue operations and clean-up efforts extremely difficult.
Death toll due to cyclones is very high. Despite their devastating effects, cyclones of low intensity are beneficial because they bring rain to dry areas and move heat from the tropical regions.

Destruction due to local storms
Strong winds due to storms can damage and destroy vehicles, buildings, bridges and other outside objects turning loose objects into deadly flying projectiles.
Local storms damage the power supply to the local region
They also damage communication and hamper rescue and relief efforts
Cloud-to-ground frequently occurs during storms
They also damage vital local infrastructure

Cumulative atmospheric hazards or disasters

CUMULATIVE ATMOSPHERIC HAZARDS OR DISASTERS

The word 'cumulative' refers to increment by successive additions. Atmospheric hazards or disasters refers to oxygen deficiency, dust, chemical vapours, welding fumes, fog or mists that can interfere with the body's ability to transport and utilize Oxygen. Such hazards have negative toxicological effects on the human body. 

Confined spaces can be found in industrial settings,public utilities and the construction industry. The safety hazards associated with confined spaces can cause serious injury and death. These hazards can be called as atmospheric hazards or physical hazards.

Atmospheric hazards include:

• Oxygen deficiency
• Oxygen displacement
• Flammable atmospheres and
• Toxic gases

Oxygen deficiency: Low levels of oxygen can be caused by consumption of Oxygen during open flame operations such as welding, cutting or brazing. In addition, low levels of Oxygen can be present in manholes that are located near garbage dumps, landfills and swampy areas where fermentation has caused the consumption of oxygen.

Oxygen displacement: Some type of gases will displace oxygen from a confined space. Sometimes Nitrogen is used to purge gases from tanks. If a person enters the tank before Nitrogen was properly removed and vented from the tank, the person could die within a matter of minutes

Flammable atmospheres: Some confined spaces could contain flammables like solvents, fuel oil, gasoline, kerosene, etc that provide fuel for combustion. For the atmosphere to become flammable, it must have the proper mixture of oxygen and fuel. A fire hazard is possible in confined spaces if the right mixture of oxygen, fuel and a spark are present.

Toxic gases: Toxic gases can be present in a confined space because of type of manufacturing processes or toxic substances during production or biological and chemical breakdown of the product being stored in the tank. Common types of toxic gases encountered in confined spaces are:

1. Hydrogen sulphide: Colourless gas with odour of rotten eggs It inhibits exchange of oxygen at the cellular level and causes asphyxiation. It causes a loss of sense of smell
2. Carbon monoxide: It is a colourless and odourless gas and inhibits the body's ability to transport Oxygen to all parts of the body
3. Solvents: Solvents such as kerosene, gasoline, paint strippers, degreasers are flammable and when inhaled at high concentrations causes Central Nervous System (CNS) effects such as dizziness, drowsiness, lack of concentration, confusion, headaches, coma and ultimately death

Two or more of the above listed hazards or disasters occurring together adds-up the effects and this is called 'Cumulative atmospheric hazards or disasters'

Impact of disasters on development projects

IMPACT OF DISASTERS ON DEVELOPMENT PROJECTS

Disasters derail development. According to the United Nations (UN), over the past two decades, disasters from natural hazards have affected more than 4 billion people, claimed more than 1 billion lives, and caused almost U.S. $ 2 trillion in economic losses. Disasters have a devastating effect on development. Apart from loss of human life and economy, the psychological impact of disasters on the mental health of the affected people leads to low attendance at work and retards the economic growth of the region in general. The impact of disasters on specific development projects is discussed below-

IMPACT ON DAMS

The drive for economic growth has exposed populations to increased risk.Destruction has been exacerbated by the development of dams in fragile ecosystems. Hence, disasters reveal boundaries and limits to development.All countries suffer from disasters but their impact is felt to the maximum extent in poor countries.In case of development project involved in construction of dams, the disasters like flash floods, earthquakes and landslides can delay the project and adversely affect the finances allocated to the project as additional expenditure will be required in operations like clearing of debris, redesigning the project to suit the changed landscape, salvaging the usable construction material and disposal of incomplete structure. The ongoing progress of the project is pushed back and the project is delayed considerably.

IMPACT ON EMBANKMENTS

An embankment is a wall of brick or stone built to prevent flooding. The natural disasters that can affect its development are Earthquakes, landslides, floods as all these disasters result in affecting the surface of the Earth. Earthquakes destabilise the foundation of the embankment causing it to collapse. Floods may weaken the bonds between the bricks and stones by dissolving the cement or water may act as a lubricant between stones causing the stones to slide against each other leading to collapse of the structure. Flood water may be absorbed into bricks and swelling of bricks may lead to cracking and ultimately collapse of the structure. Earthquakes cause embankments to collapse as the entire structure is built on land. Landslides cause a section of land to slide over another and this disturbance of land also collapses the embankments.

IMPACT ON CHANGES IN LAND-USE
Land-use refers to a particular purpose for which a parcel of land is used. Change in land-use refers to using a particular area of land for a different purpose than which it was being used. Examples of this are:

1. Clearing a forest area for residential purpose
2. Clearing a forest area for agriculture
3. Clearing a residential area for industries
4. Clearing agricultural land for industries etc

Disasters will have a profound impact on any change in land-use. This happens primarily because the local community will have experienced the area and will have the knowledge regarding the do's and don'ts in specific areas as a result of previous experience. When ever there is a change in land-use pattern as listed above takes place activities of the new community might not be in synchronicity with the ecological cycle of resource withdrawal. This might result in disasters.Change in land-use has been the most common factor in recent natural disasters.Few examples are listed below:

• Mangroves in coastal areas act as natural barriers to strong winds and storm surge associated with land falling tropical cyclones. Cutting these mangroves for agriculture removes the natural barrier and thereby increases the intensity of land falling cyclones.
• Mangrove ecosystems along the mithi river and mahim creek in Mumbai were destroyed and replaced with haphazard construction. Sewage and garbage dump also destroyed the mangroves. The Mumbai floods of July 26, 2005 is a classic example of modifying land-use contributing to a major disaster where more than 1000 lives were lost.
• Chennai floods of 2015 and floods in Bengaluru and Hyderabad have demonstrated that haphazard change in land-use has become a major source of disasters caused by natural hazards
• Major floods in Uttarakhand in 2014 and Kashmir have shown that land-use change and unplanned development have been the real cause of large-scale disasters.

Cyclones and floods

Cyclones
The word 'cyclone' is derived from a Greek word meaning 'coil of snake'. In meteorological terms, cyclone is a low pressure from all sides. A cyclone may be elliptical, circular or 'V' shaped. Cyclones can be classified as tropical or temperate based on the location where they occur. The various impacts of cyclone  are listed below:

1. Storm surge causes
1. Flooding in coastal areas
2. Erosion of beach
3. Loss of soil fertility and
4. Damage to structures
2. Winds
1. Damage to structures
2. Loss of power and communication
3. Loss of life
4. Agricultural loss and livestock losses

      3.Torrential rains

1.  Flooding in inland areas
2. Land subsidence
3. Contamination of water supply system
4. Destruction of  crops and livestock

It is difficult to measure the magnitude and intensity of a cyclone. Cyclones are usually accompanied with heavy rains and wind storms. Cyclones paralyse entire public services including communication and transportation. Damages caused by cyclones  to sanitation infrastructure causes a heightened risk of communicable disease outbreak like diarrhea and cholera.

In order to mitigate the effects of cyclones, a rehabilitation plan with geographical focus and prioritization of intervention should be prepared. The plan should contain measurable indicators like infrastructure, livelihood and habitat.

Floods

Floods are a common feature in India occurring in many areas. Floods are a natural phenomena.

Flood is a water related disaster. A flood occurs when the geomorphic equilibrium in the river system is disturbed due to intrinsic or extrinsic factors. or when the system crosses the geomorphic threshold.

1. Flooding in the river bed due to aggradation of river bed (intrinsic threshold)
2. Flooding in the river due to heavy rainfall (extrinsic threshold)

Floods in major cities especially in major cities during rainy season are disastrous not only to the environment but also has serious implications for human life and property
The different types of flood are:

1. Flash floods
2. River floods
3. Coastal flood and
4. Urban flood

According to the duration, floods can be classified as:

1. Slow-onset floods 
2. Rapid-onset floods and
3. Flash floods

Floods can also be classified as:

1. Natural
1. Storm surge
2. Tsunami
3. Glacial melt
4. Landslides
5. Riverine, Estuarine and Marine floods
6. Examples are bursting of landslide and blockades in the catchment areas of rivers
2. Man-made
1. Breach of dam / barrage / embankment
2. Release from reservoir
3. Urban flood
4. Examples are breach of almatti and narayanpur dams in karnataka

Causes of floods

1. Silting of river bed
2. Inadequate capacity within the banks
3. River bank erosion
4. Flow obstruction and change in river course
5. Common floods in the main and tributary rivers
6. Poor natural drainage
7. Cyclones
8. Retardation of flow and backwater flow
9.  Heavy rainfall

Factors influencing floods:

1. Vegetation cover
2. Climate
3. Slopes
4. Rainfall intensity and duration
5. Land use
6. Rock type
7. Lakes and reservoirs
8. Soil depth and type

Impact of floods

1. Human loss
2. Property loss
3. Affects the major roads
4. Disrupts transportation services
5.  Spread of water-borne communicable services
6. Disruption in electricity and communication services
7. Social and economic disruption
8. Pollution of air and water

Flood forecasting - Anticipating floods before they occur helps to take precautions and warn people in order to prepare people in advance for flood conditions.
In order to predict floods accurately, a long-time series of historical data that relates stream flows to measured past rainfall events is required.
Radar estimates of rainfall and general weather forecasting techniques are important components of good flood dorecasting.