Saturday, November 24, 2007

Sandstorm (Dust Storm)

Introduction

A sandstorm or a dust storm refer to a common natural hazard that occur when a strong wind blows over a dry surface of land and pick up loose sand and dust along with it, covering an entire area with sand floating in the air.

Dust Storm approaching Stratford, Texas

Causes

Sandstorms are caused by strong winds with high velocity blowing over loose soil or land, which makes large amounts of soil suspend in the air that visibility is reduced. In desert regions, sandstorms will become more frequent due to the strong heating of air, which causes instability in the lower atmosphere and produces stronger winds at the ground surface.

Human contributions to the causes of sandstorms include poor farming, deforestation, and overgrazing. Extensive farming without crop rotation can cause the nutrients in the soil to become depleted. Therefore it makes the soil poor and dry, easy to be carried away by strong winds. Cutting down forests, turning the land into non-forest land exposes the top soil to the environment. After a period of time, the top soil will become worn out so much it can be picked up easily by a gust of strong wind. Overgrazing, which is when vegetation is exposed to livestock grazing for extended periods of time, can cause desertification and soil erosion which would make the soil able to be blown up into the air by the wind.

Effects

The effects of a sandstorm can be devastating every aspect of life. The occurrence of sandstorms cause a lot of damage to agriculture, both to crops and livestocks. The sandstorms are able to turn an area into a vast desert; the abrasiveness of the winds can uproot trees and damage young crop plants. The winds can also remove the nutrient-rich organic matter and cause a decrease in agricultural productivity. As for commerce, urban communities can be heavily affected by sandstorms because everyday transactions require the use of technology and electricity. When a sandstorm hits the city, there can be a mass power outages and infrastructure damages, which would definitely affected the commerce greatly. There can also be reduced visibility in affecting aircraft and road transportation, causing many accidents. In addition, the health of the people can also be affected by the sandstorms. People can develop many respiratory diseases, especially Asthma, from breathing in sand particles and the viruses and microbes that are carried in the sand particles.

However, sandstorms also have beneficial effects; the nutrients brought over along the winds can benefit the place they deposit. Central and South American forests get nutrients from the Sahara; iron-poor ocean regions get iron, and dust in Hawaii increases plantain growth.

Dust plume off the Sahara Desert

Areas Affected

Sandstorms can be found in many places around the world. They are most commonly found in arid and semi-arid regions which are the deserts and steppes regions.

Deserts of the World


Prevention

There are many methods for preventing sandstorms. One prevent ion method is better farming, which means crop rotations and new farming techniques. With crop rotations, the soil will not
become depleted, and thus prevents the fertile top soil to be exposed to strong winds. New farming techniques include having narrow fields, wind strip cropping to lessen the damage from wind erosion, and having ridging of a field would also prevent wind erosion by holding the dust particles to the ground.

Another method for preventing sandstorms is to recover semi-arid areas through the use of technology. Recent study has shown that the use of micro-bacteria can increase the growth rate and strengthen the roots of some plants, making it possible to grow plants in the semi-arid areas. Therefore, the chance of having the dust and sand picked up by strong winds will be less.

LEDC's vs MEDC's

Sandstorms have different impact on LEDC's and MEDC's due to many factors. The most important factor is money. LEDC's will be more affected than MEDC's because they are not able to afford elaborate warning systems, thus resulting in higher death tolls and damage. Another factor that will determine a difference between LEDC's and MEDC's when faced with sandstorms is economy. The economy of LEDC's will likely drop drastically, while that of MEDC's will only function less efficiently when faced with sandstorms. That is because the economy of LEDC's mostly rely on agriculture, so when a sandstorm strikes, the agricultural productivity will take heavy damages. On the other hand, MEDC's, whose economy mostly rely on industry, will suffer little damages.

Why do people live in the hazard prone area?

People live in areas prone to facing sandstorms due to many reasons. The reasons are that the people are too poor to move or they cannot move due to some difficulties. As seen in China, which has a long history of sandstorms due to its close proximity to the Gobi desert, where people still live where they always do because people are either too poor to move to other countries or they cannot move to other places because every place is overcrowd. Another example is the population of Iraq, who had experienced a large sandstorm last April and is unable to move to other places because Iraq is war-restricted. There are other countries such as Afghanistan and Iran whose population are forced to stay inside the country because they are also war-restricted.
Beijing's Spring Dust Storm

Case Study:
Chinese Dust Storm March 2002

Causes

The dust storm started forming in the northern part of China during the hottest time of the year. The causes for this dust storm are said to be the arid weather of the north, the ploughing up of pasture land for agriculture and prevailing winds. It is said that the storm was strengthened by a severe drought that was going on in the north at that time, and that it was the worst dust storm in a decade.

A satellite image of the dust storm over Beijing

Effects

The dust storm spread itself across to the capital Beijing, South Korea, and reached as far as Russia's Pacific port of Vladivostok. Withins hours, the whole region of the storm is engulfed in yellow sand, affecting an estimated number of 100 million people. The storm also caused many traffic and aircraft delays due to reduced visibility; about 35 domestic flights were canceled and 75 were had to be called off. Children and elders were quickly warned to stay indoors. After the dust storm, Beijing is now less than 250-kilometers from the threatening desert.

Protection Measures

After the dust storm, the Chinese government had vowed to try to deal with the problems with similar natural hazard. The government had invested in $6.8 billion on an environmental program which includes a project of planting a green belt of trees around the capital Beijing to reduce the damage from future sandstorms, and to ensure the safety when the 2008 Olympics is being hosted.

Experts warned that there could be sandstorms could be a major problem for the 2008 Olympics that Beijing is hosting









Bibliography
  • http://en.wikipedia.org/wiki/Dust_storm

  • http://snrs.unl.edu/amet351/krohn/effects.html

  • http://news.bbc.co.uk/2/hi/asia-pacific/1887000.stm

  • http://news.bbc.co.uk/2/hi/asia-pacific/1883494.stm