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Effects of Natural Disasters on Environment

Natural disasters can contribute to the transmission of some diseases, especially since

water supplies and sewage systems may be disrupted, sanitation and hygiene may be

compromised by population displacement and overcrowding, and normal public health

services may be interrupted.

Disease Risks

The risk for infectious diseases among travelers to affected areas is minimal unless a

disease is endemic in an area before the disaster, since transmission cannot take place

unless the causative agent is present. Although typhoid can be endemic in developing

countries, natural disasters have seldom led to epidemic levels of disease. Floods have

been known to prompt outbreaks of leptospirosis and cholera in areas where the organism

is found in water sources (see the Leptospirosis and Cholera sections in Chapter 3).

When water and sewage systems have been disrupted, safe water and food supplies are of

great importance in preventing enteric disease transmission. If contamination is

suspected, water should be boiled and appropriately disinfected (see the Water

Disinfection for Travelers section earlier in this chapter). Travelers who are injured

during a natural disaster should have a medical evaluation to determine what additionalcare may be required for wounds potentially contaminated with feces, soil, or saliva, or

that have been exposed to fresh or sea water that may contain parasites or bacteria.

Tetanus booster status should always be kept current.

Various vaccine-preventable diseases have been eliminated or are near elimination in

some developing countries. However, if someone who has the disease travels to the

country, there is a risk of reintroducing those diseases, leading to an outbreak. Therefore,

it is very important that people traveling to offer relief or other services in countries

affected by natural disasters be protected against such diseases.

Injuries

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After a natural disaster, deaths are rarely due to infectious diseases and are most often

due to blunt trauma, crush-related injuries, or drowning. Travelers should thus be aware

of the risks for injury during and after a natural disaster. In floods, people should avoid

driving through swiftly moving water. Travelers should exercise caution during clean-up,

particularly when encountering downed power lines, water-affected electrical outlets,

interrupted gas lines, and stray or frightened animals. During natural disasters,

technological malfunctions may release hazardous materials (such as release of toxic

chemicals from a point source displaced by strong winds, seismic motion, or rapidly

moving water).

Floods

Physical damage - Can damage any type of structure, including bridges, cars, buildings,

sewer systems, roadways, and canals.

Casualties - People and livestock die due to drowning. It can also lead to epidemics and

waterborne diseases.

Water supplies - Contamination of water. Clean drinking water becomes scarce.

Diseases - Unhygienic conditions. Spread of water-borne diseases.

Crops and food supplies - Shortage of food crops can be caused due to loss of entire

harvest.[4] However, lowlands near rivers depend upon river silt deposited by floods in

order to add nutrients to the local soil.

Trees - Non-tolerant species can die from suffocation.[5]

Tertiary/long-term effects

Economic - Economic hardship, due to: temporary decline in tourism, rebuilding costs,

food shortage leading to price increase ,etc.

26th Flood July Mumbai

Mumbai came to an abrupt halt on 26th July, as unprecedented heavy rains Opening of

bank accounts made easy for the flood affected persons .

Limnic Eruptions

Consequences

Once an eruption occurs, a large CO2 cloud forms above the lake and expands to the

neighbouring region. Because CO2 is denser than air, it has a tendency to sink to the

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ground while pushing breathable air up. As a result, life forms that need to breathe

oxygen suffocate once the CO2 cloud reaches them, as there is very little oxygen in the

cloud. The CO2 can make human bodily fluids very acidic, potentially causing CO2

poisoning. As victims gasp for air they actually hurt themselves more by inhaling the

CO2 gas.

At Lake Nyos, the gas cloud descended from the lake into a nearby village where it

settled, killing nearly everyone. In this eruption, some people as far as 25 km (15.5 miles)

from the lake died. A change in skin color on some bodies led scientists to think that the

gas cloud may have contained a dissolved acid such as hydrogen chloride as well, but that

hypothesis is disputed.[4] Many victims were found with blisters on their skin. This is

believed to have been caused by pressure ulcers, which are likely to have formed from

the low levels of oxygen present in the blood of those asphyxiated by the carbon dioxide.

[5] Thousands of cattle and wild animals were also asphyxiated, but no official counts

were made. On the other hand, vegetation nearby was mostly unaffected except for that

which grew immediately adjacent to the lake. There the vegetation was damaged or

destroyed by a 5-meter (16.4 ft.) tsunami from the violent eruption.