The purpose of this report is to examine the effects the building of a dam would have on the environments in the surrounding areas. 1.2 Background
A dam is a barrier built across a river, or other waterway to hold back or control the water flow. Some dams raise the level of waterways to make them available for navigation for ships and barges. Other dams generate electric power, hold water for drinking, or provide flood control. A dam size depends on the strength needed to support the amount of water which builds up behind it. Also the depth of water behind a dam the higher pressure will be.
There are different types of dams and they can serve many purposes. Storage dams are constructed to store water for use in times of need. They may be used to improve habitat for fish and other wildlife, for hydroelectric power generation, or for a flood control project. The volume of storage available determines the height and width of the dam. Diversion dams provide sufficient pressure for pushing water into ditches or canals. They are usually used for irrigation or for diversion [hence the name] to distant storage reservoirs. Detention dams are minimize the effects of flash floods and trap sediments. Often two types of dams are combined to form composite dams and serve multiply services.
A dams structure and design is also very important, some of the types are; Earth-fill dams usually have a water-impermeable clay core and a water cut-of wall from their base to bedrock to stop underground seepage. Supplementary structures or spillways are used in conjunction with earth-fill dams to discharge water from behind them. If proper spillways are not constructed an earth-fill dam may erode away. Rock-fill dams use rock to provide stability. They have a layer or loose rock with a waterproof layer, usually concrete on top. Rock-fill dams hold water by gravity force acting on its mass. They usually require more material because loose rock and earth are less...