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.
According to the U.S. Environmental Protection Agency (EPA), barring fire, floods are the most common natural disaster affecting Americans. Floods are a factor in 90 per cent of natural disasters. Flood events have both natural and man-made causes. Storm events can create flood waters that exceed the capacity of the environment or man-made structures. Levees and dams provide a false sense of security as became evident during the Great Flood of 1993 in the Upper Mississippi River valley. A painful lesson was learnt. Wetlands destruction removed a natural means to absorb floodwaters.
Fires are nature's environmental managers. They create and maintain ecosystems such as prairies and pine forests. In fact, prairies evolved with the presence of fire. The health of the ecosystem is dependent on this disturbance. Fires remove a build-up of litter on the soil surface, allowing nutrients to be released into the environment. It also creates favourable conditions for seed germination. Suppression of fire allows litter to accumulate, setting the stage for catastrophic fires. Plants and trees have adapted to the presence of fire. However, the higher temperatures of crown fires can kill plants entirely. These fires are more difficult to control. Suppression of fires is expensive, upward of £0.6 billion annually, according to the U.S. Forest Service.
Drought has had more widespread effects than any other natural disaster. Each year, drought costs the United States more than £3 billion. It's safe to say that droughts have greater impacts in modern times. More people are affected by loss of land and food crops as well as environmental damage. The immediate effects are overshadowed by secondary issues. Compacted, dry soils are vulnerable to topsoil loss and erosion. Dry conditions make fires more common. Evidence suggest global warming may be the cause for an increase in drought frequency and changes in the global climate.
Like drought, an increase in severe weather events has been recorded in the last 100 years by the National Climatic Data Center. While notification systems are in place, vulnerabilities still exist for property damage and crop loss. Development has also complicated the effects of such events. An increase in development leads to a decrease in wetlands and an increase in impervious surfaces such as roads and driveways. This creates a scenario for floods and flash flooding. As with drought, scientists believe a link between global warming and climate changes exists.
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. Nature evolved with natural disasters and disturbance. The best prevention is looking at the strategies found in nature.