Kathy Poon 6S 28
5. Discuss on the impact of land clearance and reclamation for residential and urban infra-structural development on the environment.
With the high rate of urbanization and industrialization, land clearance and reclamation are the general practices to satisfy the demands for lands for development. Land clearance involves the conversion of agricultural lands and natural areas into a form that is suitable for urban and industrial development. Reclamation involves the establishment of lands on the sea in coastal areas.
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Land clearance and reclamation have contributed to the social and economic development in various parts of the world. However, these human activities have been causing undesirable effects on the natural environment. They are responsible for destroying natural habitats and hence threatening biodiversity. They are also responsible for degrading environment quality, leading to soil erosion and pollution.
The impact of land clearance on the environment is that, forests may be for urban and industrial development. New urban and industrial areas are also converted from agricultural lands. This may have dramatic effects on the soil conditions. Soil may be washed away from the bare ground during heavy rainfall. This may pollute the aquatic environment and also threaten aquatic lives.
On the other hand, the impact of land reclamation on the environment is that land reclamation for urban and industrial development usually involves topographical and hydrological modifications. The operations include draining and filling of marshes and wetlands, constructing residential houses or resorts on beaches or dunes, building seawalls and extending the shoreline into the sea, etc. these cause impact on marine environments. Reclamation often involves the dredging of soft mud at the site and loading of a large quantity of materials into the site for land formation. All these practices have direct impact on marine organisms, especially coral reefs. Coral reefs provide a highly protective barrier for coastlines, such as beaches, from the continuous pounding of ocean waves. They also provide an intricate and complex habitat for a variety of fish, mollusks, echinoderms and crustaceans. Land filling can also directly kill these marine organisms. Physical removal of seabed can cause immediate injuries to the natural marine communities. Clouds of suspended sediment adversely affect marine life through the decrease in light penetration into water for photosynthesis of seaweed and phytoplankton. In addition, certain constituents of sediment may react with substances in the sea and lead to an increase in water temperature. As a result, water holds less oxygen and this can be detrimental to marine lives.
There are some impacts of urban and industrial development on the environment. Urbanization and industrialization exert pressures on the environment. The loss of trees, shrubs, and other natural vegetation results in the destruction of habitats for wildlife. These also result in soil erosion and extinction of some native species. The conversion of farmlands into urban areas results in the reduction of food productions. The rapid migration of people from rural areas to urban areas results in an increasing consumption of resources, such as fresh water and fossil fuels. Roads and buildings do not absorb rainwater as vegetation does, leading to flooding and landslide problems. The production of pollutants from industries, vehicles and burning of fossil fuels in power stations cause serious air pollution, leading to acid rain and global warming. Domestic and industrial sewage seriously pollute the aquatic bodies, and may also cause health problems to human and aquatic life. The incineration of solid wastes further contributes to environment problems, such as global warming and air pollution.