Desertification also takes place and is often blamed on the in-migration of farmers who exploit soils to such an extent that the nutrient levels decline and plants cannot become established. The whole landscape changes due to increase surface runoff and erosion.
In America there has been a huge flow of migration from the North down to the south known as the ‘Sunbelt’. The impact on the environment has been considerable; however there are some positives to this relocating. Many of the northern cities have been cleaned up and the number of pollutants to the Great Lakes has also decreased dramatically. Unfortunately, there are many more negatives issues in the South including loss of habitat in deserts which have recently been built on for leisure activities such as golf courses and 4WD courses. The water demands in cities such as LA and Las Vegas means that more water is being withdrawn from rives such as the Colorado or by removing groundwater. This has led to major changes in the Colorado delta where the water barely reaches the sea. Also, with living in desert cities the use of air-conditioning systems both raises the urban temperature by as much as 2 degrees Celsius and emits chlorofluorocarbons into the atmosphere and damages the ozone layer.
Land and Agriculture is a one reason why there has been migration in the past century. The Mechanisation has taken place throughout many countries and cities and this
Mining has several environmental impacts such as water pollution and habitat destruction. In the Guianas and the Amazon, migrant gold miners use mercury to extract gold; mercury poisons water bodies, affecting people and freshwater biodiversity. Miners and loggers in many forest areas also hunt for meat or pay local hunters to hunt for them, which can result in severe reduction in wildlife populations. Migrants face the choice of moving on in search of new opportunities or staying to develop new livelihoods. For example, Miners in the Zambian Copperbelt region confronted this choice when the declining price of copper on the world market resulted in the closure of mines over the past few decades. Many of those formerly employed in the mining industry and its associated services remained in the region, moving into rural areas around the towns to practice slash-and-burn agriculture, charcoal production and livestock rearing, threatening the ecologically sensitive Miombo woodland. However this is beginning to turn its self around as the copper prices are firm and the old are new mines are now operational .
In Brazil, government subsidies and construction of roads in the 1960s resulted in a westward expansion of people to tap the vast interior wealth of the Amazon. Several government-sponsored programs initially provided free land and food for six months in Rondonia and elsewhere to attract migrants However, many of the original settlers faced
severe problems due to poor soils and declining yields, long distances to markets, difficulties in land titling and lack of credit. Many sold or abandoned their land and migrated either further into the rain forest to clear new plots or to the boomtowns of the region. Large cattle ranches contributed to continuing deforestation in the eah a huge scale, and
is still advancing. This is resulting in vast biodiversity loss. It is also expected to change the climate in the Amazon Basin through reduced rainfall and evaporation and increased surface temperature. These impacts will be felt beyond
the Amazon itself, both regionally and globally. Between 25 and 50 percent of rain falling in southeast Brazil originates in the Amazon, and São Paulo in particular is likely to suffer if the Amazon’s climate changes due to deforestation.
Development of road networks ,often opens up areas previously inaccessible areas to migrants. With settlement comes increased land clearing, resource extraction, pollution and hunting. In addition, new roads can bring new large-scale commercial resource extraction, such as mining and timber harvesting. Roads can also disrupt environmental processes such as animal migration and plant dispersal. Large-scale road construction is currently underway in many areas, such as the Amazon, Mekong and Congo basins. In Cambodia soon to be completed Route 48 will provide a crucial link for transport from Bangkok, Thailand to Phnom Penh, Cambodia and Ho Chi Minh City and Hanoi in Vietnam. The organization WildAid has dedicated itself to protecting the forested areas on either side of the road to try stop deforestation due to migration to set up new towns and villages.
Armed conflict can result in large-scale and often sudden movements of people, who migrate when their livelihoods and well-being are threatened. This can cause mass destruction on the environment. For example Zaire in 1994 when there was ethnic cleansing and civil was going there was huge migration movements across borders. More than 1.2 million people migrated to the small town of Goma within 3 days. One million people living in crowded conditions with inadequate shelter, inevitably contaminated water sources, and no sanitation because of the volcanic environment, was a formula for disaster in a region where both cholera and dysentery were known to be endemic. Deforestation occurred within 3 days and over 300 hectartes of Mount Goma had been destroyed, the sudden influx of migrants caused irreversible damage to the vegetation. An estimated 7,000 -10,000 m3 of wood and grass were being collected from the park by refugees every day from August to December 1994. Water diseases such as Cholera began to spread and the only water source was Lake Kivu and this was sometimes up to 10km away. Water needed to be brought in. 60 trucks were used daily to carry up to 2 million liters of water per day to 68 locations in the campsites. Chlorine was added as the trucks left the Lake, and after traveling for 90 - 120 minutes, was suitable for consumption. Sanitation soon started to become a big problem as well. There were no toilets Refugees defecated where they stood, slept and ate. The situation was no better when many had moved out of Goma to the other sites. All were situated on volcanic rock - no holes could be dug - either to defecate, or bury their dead. This has caused mass damage to the environment and unfortunately this will takes centuries to return back if it ever will.
As the population continues to increase this will continue to make migration increase, there are ways that people can try and minimize the impact on the environment however it is starting to become too late.
