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

Impact of land clearance

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.

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, mollusks, 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.