The Making Of a Dam
What is a dam? It is a wall built to hold back the water of a creek, stream, or river. But that's not all it is. I wanted to find out what a dam did and how it worked. I did my project on it for that simple reason. I did a project showing how a dam worked. The following information is what I found out about dams. Here is my report.
The earliest dams were used for to water farms. The early Egyptians made dams of dirt that were made to raise the level of the water so it could reach their farms. The pilgrims even made dams when they first came to North America. Their dams where used to turn their wheels to grind the corn and to saw the timber. An artificial lake that is made by a dam is called a reservoir. The part of the dam over which the water spills is called the spillway. Water can pass over the dam also. It can also get through by chutes, tunnels, or shafts. The pipes for conducting the water to the power turbines are called penstocks. All the water that flows through is controlled by control gates. Dams are manly built for water supply, irrigation, electric power, flood control, and also improvement of navigation. A lot of dams have more than one purpose. Dams that deal with irrigation store the water and supply the crops with it when the going gets tough. Some dams can direct the water into pipelines and other irrigation instruments. There are also water supply dams. These dams supply the large cities with water. Flood control dams keep the river from overflowing. They release the water at the bottom of the dam and this way they can control the water below. There are also navigation dams. These are built so a ship will have the right depth of water. The passage of a river may be blocked by a waterfall of rapids. By putting in a dam you can "drown" the problem. Some dams are built to generate power. Hydroelectric dams do just that. They direct the water into turbines. These are wheels curved blades as spokes. These are the main things that a dam can do. But there are other things it can do as well. It provides recreation. People like to go swimming, they like to fish, and they like to watch the animals that are attracted to the water. Dams are very important to birds and other animals. Dams also slow down streams so the soil is not carried away. Dams can also create problems. The reservoirs many cover up historic places and also scenic places. IT may also cause a problem for fish when they move up stream. There are other structures that are like dams too. These are called cofferdams. These dams are only temporary to hold back the water. Dikes keep the sea off land that is below sea level. There are also levees. These are artificial riverbanks that prevent the water from flooding. A very small dam that is used over a millpond or a fishpond is called a weir. There are main types of dams. They are classified into different groups. They are classified into groups by design, method, and materials. The usual types of masonry or concrete, rock, earth, timber, steel, anc moveable dams. Concrete dams are either arched, solid gravity, or hollow gravity. Solid gravity dams: they are made of solid concrete. They withstand pressure. In cross section they are like a triangle. They are built like this because water pressure becomes greater as the depth of the water in increased. Hollow gravity dams: Made with less concrete than solid gravity dams. They rely more on their structure than there weight to resist the force of the water. There are three types of hollow gravity dams. The multiple arch dam has a number of arches supported on buttresses. A flat slab dam is a straight wall resting on buttresses. The multiple dome dam has domes instead of arches. It is like the multiple arch dam. Arched dams: they consist of a horizontal curve using the principle of the arch for strength against water pressure. They are curved upstream. The force of the water is then put to the canyon walls. Earth dams are made by putting clay, gravel, and sand over a river. Often a core, or a wall built inside the dam is put to prevent leakage. Rock dams are made by placing rocks across a river. Over this concrete, timber, or steel is placed. A wall of rocks is often laid upstream.
Purpose Of This Project
The purpose of this project is to show how you can turn a useless river into a valuable asset. One part of my model shows a useless, shallow, stream. The other part shows how a dam can change all of that. It provides a source of power, irrigation, and recreation. I built a model dam for my science project. I wanted to demonstrate what I wrote above. A dam is important the world today.
three plastic straws
thin, stiff plastic
wire coat hanger
two catch pans
two flexible tubes
wood (the measurements are difficult to tell)
1. Cut the wood to the length that is required. The wood must be 1/4 inch thick
2. Nail the wood together so it looks like two troughs.
3. Waterproof the model down the middle of each trough with caulking compound.
4. Paint the model with a green waterproof paint. You should layers of paint on the model just to be sure that the water does not go through.
5. Drill three holes in the triangle that will be the dam. Secure this into one of the troughs. Use caulking compound.
6. Use a green sponge or something else that resembles trees to put on the side if each river. This will create the trees that are on the side of every river. Make the trees thick around the dam to show how the plant-life is thicker there in real life.
7. Make the turbine out of the cork and the stiff plastic, placing the plastic around the cork. Drill a hole in the middle of the cork and stick the wire of the coat hanger through it. Secure this to the model a the base of the dam.
8. Put three straws in the holes in the triangle piece that is the dam. Two of the straws that are on the outer edges must have holes in them made with a pin that are an inch apart. Plug the end of the straws with a clay.
9. Fill the bucket with water and put one end of the tubes into it. Place the other at the top of the model. Let the water run down the model into the catchpans.
I did this project to find out more about dams. I hope that by looking at this project and reading my report that you now know more about dams too. Dams are important. I just hope that you now think so too.