5.Discuss on the impact of land clearance and reclamation for rseidential and urban infra-structural development on the environment.

Humans have increasingly altered the natural environment for various purposes such as settlement,agriculture and industry.They have also increasingly replaced the natural landscape with the urban and industrial establishments.

Urbanization and industrialization are proceeding all over the world at an unprecedented rate.Because of social and economic development,there have been rapid changes of land use from agricultural purposes to urban and industrial purposes.Today,many new urban and industrial areas are also established on lands reclaimed from the sea.

Urbanization and industrialization bring about intensive economic growth and technological development.However,they are responsible for creating serious environmental problems.For instance,water pollution arises from industrial and domestic sewage,and air pollution arises from industrual processes and the burning of fossil fuels to generate electricity.

With the high rate of urbanization and industrialization,land clearane 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 estblishment of lands on the sea in coastal areas.

To support a population of about seven million,reclamation has been done extensively to meet the demands for housing,commerce,industry,transport and other facilities.

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 environmental quality,leading to soil erosion and pollution.

The impact of land clearance on the environment

Forests may be cleared for urban and industrial development.New urban and industrial areas are also converted from agricultural lands.This may have dramatic effects on the soil condition.Soil may be washed away from the bare ground during heavy rainfall.This may pollute the aquatic environment and also threaten aquatic lives.

The impact of land reclamation on the environment

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 great 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,molluscs,echinoderms and crustaceans.Landfilling 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 the 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.

Impacts of urban and industrial development on the environment

Urbanization and industrialization exert pressures on the environment.The undesirable effects are listed as follows:

-The loss of trees,shrubs,and other natural vegetation results in the destruction of habitats for wildlife.These also results in soil erosion and extinction of some native species.

-The conversion of farmlands into urban areas results in the reduction of food production.

-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 rain water as vegetation does,leading to flooding and landslide problems.

-The production of pollutants from industries,vehicles and burning of fossil fuels in powder 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 environmental problems,such as global warming and air pollution.