What are the causes of natural disasters?

Why are there natural disasters? What are the causes of natural disasters? Today, I understand why Bian Xiao has brought natural disasters to everyone. Let's have a look!

Causes of natural disasters Natural disasters (natural and man-made)

1, flood disaster

Typical areas of China:

Northeast China; Middle and lower reaches of Yellow River and Yangtze River; Huaihe river basin; Pearl river basin, etc.

Reason:

(1) Natural reasons: precipitation lasts for a long time and is concentrated (such as rainy weather in the Yangtze River basin); The change of summer monsoon intensity (the second highest intensity: drought in the south and waterlogging in the north; Weak subtropical high: waterlogging in the south and drought in the north); The influence of typhoon; Lack of natural rivers flowing into the sea (Huaihe River); Low-lying (Haihe River, Pearl River); There are many tributaries of the water system (fan-shaped water system and dendritic water system); River bend (Jingjiang reach); El Nino phenomenon, etc.

(2) Man-made reasons: excessive logging leads to increased soil erosion and river bed uplift; Reclaiming land from lakes; Unreasonable construction of water conservancy projects (Weihe River Basin)

Prevention and control measures: planting trees and building shelter forest system; Returning farmland to lakes; Building water conservancy projects; Bend and straighten, and reinforce the levee; Excavation of the river channel into the sea (Huaihe River); Construction of flood diversion area; Establish a flood forecasting and early warning system.

2. Sandstorm phenomenon

Typical areas of China:

Northwest; North China

Reason:

(1) Natural causes: the influence of fast moving cold front weather; Dry climate, less precipitation; There are many strong winds in spring; The surface vegetation is scarce, etc.

(2) Human factors: overgrazing; Excessive logging; Excessive reclamation

Governance measures:

Formulate grassland protection laws and regulations and strengthen management; Control the carrying capacity of livestock; Build? Three North Shelterbelt? Architecture; Returning farmland to forest and grassland; Building artificial grassland; Advocate rotational grazing; Cutting Nostoc flagelliforme is prohibited.

3. Earthquake

Typical areas of China:

East coast; Southwest and northwest regions

Reasons for formation:

Located at the junction of the Asia-Europe plate, the Pacific plate and the Indian Ocean plate, the crustal activity is strong.

Causes of heavy loss of personnel and property may include:

The magnitude is large and destructive; There are many cities near the epicenter and the population is concentrated; Shallow earthquakes may occur at night; Induced other disasters, etc.

Measures to mitigate disasters:

Actively carry out publicity and education on disaster prevention and mitigation to raise public awareness of environmental protection and mitigation; Establish a disaster monitoring and forecasting system; Strengthen the management of geological disasters and establish and improve the system of disaster reduction policies and regulations; Improve the seismic strength of buildings; Planting trees and establishing a shelter forest system; Strengthen international cooperation, etc.

4. Geological disasters in Southwest China are serious.

Reasons for formation:

(1) Natural causes: the mountains are vast, the rocks are broken and the weathering is serious; The wet and dry seasons are distinct, and the rainstorm is concentrated; Crustal movement is strong and faults are developed in the mountain.

(2) Man-made reasons: destruction of vegetation.

Governance measures:

Restore vegetation

# # # # Ecological problems # # #

1, soil erosion problem

Typical areas of China:

Loess Plateau, southern hilly areas

Reason:

(1) Natural causes: concentrated precipitation and rainstorm in monsoon climate; The surface vegetation is scarce; Loess Plateau with loose soil.

(2) Man-made reasons: the destruction of vegetation; Irrational farming system; Mine.

Governance measures:

Compress agricultural land and expand forest and grass planting area; Afforestation; Comprehensive management of small watersheds.

The importance of governance:

It is conducive to adjusting the industrial structure according to local conditions, making agriculture, forestry and animal husbandry develop in an all-round way, increasing farmers' income, promoting local economic development, improving farmers' living conditions and improving their quality of life; Conducive to improving the local ecological environment and establishing a benign ecosystem; The establishment of ecological agriculture model is conducive to promoting the sustainable development of ecology and economy.

2. Desertification

Typical areas of China:

Northwest China (Xinjiang, Qinghai, Inner Mongolia and other places)

Reason:

(1) Natural causes: global warming, strong evaporation; Located inland, with little precipitation; Rodents; Locust disaster.

(2) Human factors: overgrazing; Excessive logging; Overculture; Unreasonable utilization of water resources; Improper protection of traffic lines and other projects.

Governance measures:

Formulate grassland protection laws and regulations and strengthen management; Control the carrying capacity of livestock; Build? Three North Shelterbelt? Architecture; Returning farmland to forest and grassland; Building artificial grassland; Advocate rotational grazing; Cutting Nostoc flagelliforme is prohibited.

Governance significance:

It is conducive to adjusting the industrial structure according to local conditions, making agriculture, forestry and animal husbandry develop in an all-round way, increasing farmers' income, promoting local economic development, improving farmers' living conditions and improving their quality of life; Conducive to protecting land resources and improving local ecological environment; Conducive to promoting the sustainable development of ecology and economy.

3. Drought and water shortage.

Typical areas of China:

North China, Northwest China and the Middle and Lower Reaches of the Yangtze River

North China:

Reasons: (1) Natural reasons: temperate monsoon climate, less annual precipitation and small river runoff; The variability of precipitation is large; Evaporation is strong in spring.

(2) Human factors: dense population, developed industry and agriculture, and large water demand; Serious water pollution; Too much waste and low utilization rate; Water consumption for spring planting is large in spring.

Governance measures: South-to-North Water Transfer Project; Building a reservoir; Control population and improve quality; Reduce water pollution; Reduce waste and improve utilization rate; Restrict the development of high water consumption industries; Developing water-saving agriculture; Adopt drip irrigation and sprinkler irrigation agricultural irrigation technology to improve utilization rate; Implement water price adjustment and establish water-saving consciousness; Desalination of seawater, etc.

(Thinking: Why is there no spring drought in Northeast China? )

4. Secondary salinization of soil

Typical areas of China:

Huanghuaihai Plain, Ningxia Plain and Hetao Plain.

Cause: (1) Natural cause: frequent droughts and floods (Huanghuaihai Plain); Low terrain; There is little precipitation, mainly irrigation water. (2) Human factors: unreasonable irrigation; Irrational construction of water conservancy projects (Weihe Plain)

Control measures: introducing light and spraying salt; Well drainage and well irrigation; Biological measures; Farmland cover; Reasonable irrigation, not just irrigation; Adopt sprinkler irrigation and drip irrigation technology.

5. Land subsidence and salinization in coastal areas.

Typical areas of China:

Large areas in the north and cities in the south

Reason:

Excessive pumping of groundwater

Governance measures:

Control the pumping of groundwater; Implement rainy season replenishment

6. Red tide

Typical areas of China:

Pearl River Estuary, Hangzhou Bay, Bohai Sea, etc.

Reason:

(1) Natural causes: high temperature; Still water; Quiet wind; The sea area is relatively closed.

(2) Human factors: the coastal areas are densely populated and economically developed, and industrial and domestic sewage is discharged into the sea; A large number of fertilizers and pesticides are used in agricultural production; Due to the improvement of marine development and the expansion of aquaculture scale, aquaculture waters have been seriously polluted.

The medium of natural disasters affects many infectious diseases, not only from person to person, but also from other biological hosts. Some diseases must be transmitted through biological media. Disaster conditions have destroyed the old ecological balance among human beings, host animals, biological media and disease pathogens, and will establish a new ecological balance on a new basis. So the impact of disasters on these diseases will be more lasting.

(1) flies

Flies are important vectors of intestinal infectious diseases, and their breeding and reproduction are mainly determined by the unsanitary living environment of human beings. Major natural disasters will always cause great damage to the sanitary conditions of human living environment, and the breeding of flies is almost inevitable.

After the earthquake, the house collapsed. Buried under the ruins are the bodies of dead people and animals, as well as a lot of things and other organic substances. Under the climatic conditions of temperature, these organic components will rot rapidly, which provides conditions for flies to reproduce easily. Therefore, earthquake damage as large as Tangshan earthquake often causes a surprising number of adult flies in a very short time, posing a serious threat to the residents in the disaster area.

After the flood recedes, drowned animal carcasses and all kinds of organic garbage will be largely silent in the ruins of the old village, and if they are not removed in time, a large number of flies will also breed.

Even in the case of drought, due to lack of water, there will be some unsanitary conditions, which is conducive to the breeding of flies. Therefore, in the early stage of post-disaster reconstruction, eliminating flies will become an important task of infectious disease control.

(2) mosquitoes

Among the blood-sucking arthropods that spread diseases, mosquitoes are the most important and closely related to disasters. Under the common disaster conditions in China, malaria and Japanese encephalitis are the most serious threats to the residents in the disaster areas.

Mosquitoes need a small and still water body to breed. Therefore, in flood water, the increase of mosquito density is often not obvious during flood discharge. However, after the water recedes, a large number of small waterlogged areas often appear in the low-lying areas of waterlogged areas, which are overgrown with weeds and become the best breeding grounds for mosquitoes. At this time, if there is a source of infection, the incidence in this area will increase rapidly.

Drought will cut off some rivers and dry up lakes, and the small puddles left in these rivers and lakes will also become good breeding grounds for mosquitoes.

In earthquakes, wind disasters and other disasters that cause a lot of damage to buildings, water storage buildings and pipelines may be damaged at the same time. The overflow of tap water, especially domestic sewage stranded on the ground, will also become an environment for mosquitoes to multiply.

Disasters will not only increase the density of mosquitoes, but also increase the chances of mosquitoes attacking humans. Residents trapped by floods and forced to sleep outdoors due to the destruction of houses often lack effective means to resist mosquito invasion, which is also an important reason for the increase in the incidence of mosquito-borne diseases.

(3) Other blood-sucking arthropods

Under disaster conditions, the chances of blood-sucking arthropods attacking humans are mainly increased, and mosquitoes sometimes mechanically spread some rare infectious diseases, such as anthrax. People who sleep in places rich in weeds and humus are vulnerable to chigger mites and gamasid mites. In areas with tsutsugamushi disease and epidemic hemorrhagic fever, this threat to human beings has greatly increased. Disasters in forest areas, such as forest fires, will increase the chances of tick bites and may lead to a series of diseases such as forest encephalitis, Lyme disease and spotted fever.

(4) Parasites

In China, the distribution of schistosomiasis is mostly in some flood-prone areas, while the distribution of snails is greatly affected by floods.

In normal times, the distribution of Oncomelania hupensis constantly changes with the scouring of water and the formation of shoals. Under flood conditions, it is possible to take snails away from their original breeding grounds and settle down in a new and suitable environment. Therefore, floods often significantly expand the distribution area of schistosomiasis.

(5) Livestock

Domestic animals are important hosts of many infectious diseases. For example, pigs and dogs are hosts of leptospirosis, pigs and horses are hosts of Japanese encephalitis, and cattle are hosts of schistosomiasis. When a flood disaster occurs, a large number of victims and livestock are often trapped in their narrow areas by floods. The natural return to the sea has caused great damage to houses, and it will also lead to an unusually close relationship between people and livestock. This environment will make it easy for people and animals to spread infectious diseases.

(6) Domestic and wild rodents

Domestic and wild rodents are the most important disease hosts, and their distribution and density are obviously affected by natural disasters.

Most rodents related to diseases live in underground caves, and their swimming ability is not very strong. Therefore, when a large-scale flood occurs, the number of rodents will decrease. However, some rodents may use floating objects to escape and concentrate in the higher places where the victims live, thus forming an unusually high density in some areas. In this case, due to the close contact between humans and rodents, it is possible to cause the epidemic of diseases.

Because of the strong reproductive ability of rodents, they usually leave abundant food for rodents in villages and farmland damaged by floods. Therefore, after the flood recedes, the density of rodents may rise rapidly, and a very high population density will appear for a period of time thereafter, thus promoting the epidemic of infectious diseases and endangering human beings.

Drought may dry up some lakes and swamps and turn them into overgrown lowlands. This area provides a superior living environment for wild rodents, which makes their number increase sharply. It is reported that this situation leads to epidemic hemorrhagic fever in the population.

Natural disasters such as earthquakes have caused a large number of houses to be destroyed, and some houses that were not easily invaded by rodents have been destroyed. A large amount of food left in the ruins has enabled domestic rodents to obtain a large number of breeding conditions. When post-disaster reconstruction begins and residents move back to their original houses one after another, rodent infestation may become a major problem, and the incidence of diseases transmitted by rodents may also rise.

In view of the impact of the above-mentioned natural disasters on the incidence of infectious diseases, the prevention and control of infectious diseases after natural disasters should have different characteristics from usual, and the organization and leadership of prevention and control should be related government departments. According to the characteristics of infectious diseases in disaster period, the control of infectious diseases can be divided into four periods.

(1) Pre-disaster period

China is a big country, and some areas are prone to natural disasters. Therefore, preparations should be made before disasters occur, including the prevention and control of infectious diseases.

1. Accumulation of basic data. In order to formulate scientific prevention and control countermeasures in times of disasters, attention should be paid to the accumulation of basic data in peacetime, including population data, health data, incidence data of infectious diseases, distribution data of major endemic diseases and distribution data of major animal hosts and vectors.

2, formulate infectious disease control plan. In some disaster-prone areas, such as earthquake-active areas, low-lying areas in the lower reaches of major rivers and flood diversion areas, there should be emergency plans when disasters occur, including infectious disease control plans. The plan should determine the focus of disease prevention in different periods according to the specific situation of each disaster-prone area. The deployment of mobile teams that can be sent to disaster areas, as well as the storage location and deployment plan of urgently needed disease prevention materials and equipment, should also be considered in prevention.

Due to the sudden occurrence of natural disasters, it is impossible to make a plan for every area that may be affected. In order to facilitate demonstration, we should make a more detailed plan according to some typical areas.

3, mobile epidemic prevention team to prepare. Due to the impact of natural disasters, disaster areas often do not have enough health and epidemic prevention and medical strength to deal with emergencies that have occurred. In the face of sudden disasters, the existing epidemic prevention teams are often in a state of temporary confusion and paralysis. Therefore, when a major natural disaster occurs, it is necessary to send a mobile epidemic prevention team into the disaster area to support disease control.

4. For some disaster-prone areas, the personnel of these mobile teams should be trained regularly to let them know about the health and diseases in the main mobile direction and the problems they may encounter after entering the disaster area. When the personnel changes, the personnel of these mobile teams should also be supplemented and adjusted in time to cope with emergencies at any time.

(2) Disaster shock period

When a large-scale natural disaster strikes suddenly, it is almost impossible to carry out effective disease prevention and control. However, during this period, medical teams sent to disaster areas for the purpose of emergency rescue should be equipped with enough drinking water disinfection places and drugs to prevent and treat intestinal infectious diseases, and pay attention to the signs of large-scale infectious diseases and carry out appropriate treatment to control the initial outbreak of diseases.

(3) Post-disaster period

When residents in disaster areas are out of danger and temporarily live in safe areas, disease prevention and control should be carried out systematically:

1, rebuild the surveillance system of mass diseases.

Due to the impact of major natural disasters, the disaster relief work is heavy and the personnel flow frequently, the disease monitoring and reporting system established at ordinary times is often paralyzed in the early days after the disaster. Therefore, the primary task of the health management department and the mobile epidemic prevention team should be to rectify it and re-establish the epidemic reporting system according to the situation of the victims, so as to find the epidemic situation in time and deal with it correctly. The contents of monitoring should include not only the legally reported infectious diseases, but also the temporary residence and mobility of the population, the occurrence of major diseases, and the number of rodents and vectors in and around the residents' temporary residence.

2. Rebuild the safe drinking water system.

Because the destruction of water diversion system poses the most serious threat to people, all possible measures should be taken to restore and ensure the safe drinking water supply first.

3. Vigorously carry out health campaigns.

Improving the sanitary conditions of temporary shelters after disasters is an important link to reduce the occurrence of diseases. Therefore, when residents are basically out of danger and arrive at a safe place, they should be organized to continuously improve the sanitary conditions at home, remove garbage and dirt, spray pesticides regularly to reduce the density of mosquitoes and flies, and carry out rodent control when necessary.

When reconstruction begins after the disaster, the sanitary conditions of the original residence should be improved before moving back to the original residence.

4. Prevent the invasion of blood-sucking insects.

It is impossible to reduce the density of blood-sucking insects to a safe level when residents are forced to sleep outdoors. Therefore, the main means to prevent insect-borne infectious diseases is to prevent insect bites. You can use all possible methods to protect people from the bites of blood-sucking insects such as mosquitoes. For example, use plants with natural insect repellent function to kill and drive mosquitoes, and try to transfer mosquito nets, mosquito repellent and other materials to the disaster area.

5, timely find and deal with the source of infection.

Under the condition of major natural disasters, it is often difficult to improve the phenomenon of crowded population and mixed living of people and animals in a short time. Therefore, finding patients and timely and correct isolation treatment are the basic means to reduce infectious diseases.

Some diseases, such as hepatitis and malaria, are the only source of infection. Therefore, residents in disaster areas should pay special attention to finding such patients in time and transferring them to medical units with isolation conditions for treatment.

In addition, many diseases can occur not only in humans, but also in animals. Therefore, it is necessary to pay attention to the inspection of domestic animals such as pigs, cattle, horses and dogs in the disaster areas, find the infection of leptospira, schistosomiasis and Japanese encephalitis in time, and deal with the animals that become the source of infection in time.

6, out of the crowd for diagnosis.

After the fire, a large number of people will leave the disaster area in the form of engaging in labor activities or visiting relatives and friends. Therefore, in the surrounding areas of the disaster area, especially in large and medium-sized cities, people from the disaster area should be specially inspected to find the epidemic signs of infectious diseases in time. In some endemic areas, these floating population should also be immunized to avoid the outbreak of some endemic infectious diseases.

(4) after-effect period

When the affected people moved back to their original places of residence and started post-disaster reconstruction, the prevention and control of post-disaster infectious diseases entered the stage of aiming at post-disaster effects.

1. Carry out physical examination and immunization for the returned population.

At this stage, the population flowing out of the disaster area began to return home one after another, and the focus of infectious disease prevention and control work should be shifted to prevent the returning population from having a second peak.

People who go out to engage in labor services may enter some epidemic areas, get infected there, and may bring the host and media of the disease back to their hometown. Therefore, inspection should be strengthened among returnees to find out which endemic areas (such as plague, brucellosis, schistosomiasis, etc.). They have arrived and checked these possible situations. If patients are found, they should be treated immediately.

Babies born in other places often lack immunity to some common diseases in their hometown, so it is necessary to strengthen the examination of infants and young children in order to find and treat their diseases in time.

Because it is difficult for floating population to carry out normal planned immunization work, there is often an immunization gap between these populations. Therefore, timely supplementary immunization is an important measure to prevent the incidence from rising.

2. Reconstruction of disaster areas and re-investigation of diseases.

Natural disasters can often cause the expansion of animal infectious diseases such as schistosomiasis, leptospirosis and epidemic hemorrhagic fever, and lead to changes in the distribution and epidemic intensity of animal diseases. Therefore, in the post-disaster reconstruction period, we should re-investigate the distribution of these diseases and take corresponding preventive measures to prevent them from breaking out during the reconstruction process.

For families and individuals in disaster areas, we should pay attention to the following points:

(1) Pay attention to the cleanliness of drinking water. If possible, listen to the guidance of disaster relief personnel and strictly disinfect with drugs. If there are no conditions, try to boil the water before drinking. Never quote polluted water just because of trouble.

(2) Cooperate with disaster relief personnel to kill flies, mosquitoes and rats and do everything possible to prevent mosquito bites.

(3) found abnormal situation, such as someone around sick, have a fever, suffering from skin diseases, etc. , should immediately report to the disaster relief personnel or relevant departments.

(4) Try to avoid multiple people living in the same room, and try to avoid sleeping with animals, even their own poultry and livestock.

⑤ Unless necessary, don't move at will without the organization and guidance of relevant personnel. People who go out should not rush into the disaster area because they care about the safety of their relatives and friends.

⑥ When the supply of tap water and other water sources is interrupted after the disaster and residents need to drink groundwater, fire water and other water, attention should be paid to ensuring the safety of drinking water. If the tap water supply is interrupted after the disaster, bottled water should be given priority, or boiled in a designated place for drinking.

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