Introduction
A dam is a physical structure that slows or restricts the flow of subsurface or surface water. Dams build reservoirs that serve multiple purposes, including flood control, irrigation, human consumption, industrial use, aquaculture, and navigability. Although they are more frequently erected on rivers, dams can be constructed anywhere. They may also be built on streams and estuaries.
What is a Dam?
A dam is a sizable, barrier-like structure that is erected across a body of flowing water. Water is held back and stored for later use because of construction. A reservoir is a term used to describe the vast amount of water storage created on the upstream side of a river when it is prevented from flowing by a barrier. Floodgates on dams can be opened or closed to allow only a small flow for human use.
During floods, gates also enable the release of extra water from the reservoir side. A surplus of water collects on the reservoir side of a river when it floods. To let surplus water out, the floodgates are slowly opened. Dams are primarily built for this reason.
For more help, you can Refer to lesson 16 – Water in Science Class 7. Checkout the video Lesson for a better understanding
Uses of Dams
- Irrigation: In recent years, irrigation for crops has primarily been provided by dams. Rainfall in tropical nations like India is only experienced for a portion of the year. However, agriculture is a year-round industry that uses water for growth, depending on the stage of growth. While others, like rice and sugarcane, require excessive amounts of water. Agriculture was made possible by irrigation, even in remote areas with low subterranean water levels.
- Electricity: The floodgates are opened, allowing the reservoir’s water which is already under high pressure to pass through the turbine that powers the generator. A turbine transforms the kinetic energy of water into mechanical energy, which is then transformed into electrical energy by a generator.
- Reservoirs are a great place for recreation. Many reservoirs provide the local people with camping, boating, and fishing facilities.
Advantages of Dams
- Hydroelectric power, which is produced by dams, is independent of all fossil fuels. As a result, hydroelectricity is a source of energy that is constantly replenishing and can be used. With a growing population comes a rising need for energy. One of the safest methods to address the energy situation is using hydroelectric electricity.
- A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity.
- You can irrigate with the reservoir water. Crop plants can be effectively watered across long distances. Food is produced on the irrigated farmlands. Demands for drinking water are alarmingly rising along with population growth.
- Floods are prevented by dams, which redirect water flow. Numerous lives are saved every time water is slowly released from reservoirs through floodgates, and property damage is also avoided.
- A reservoir is a gathering place for many aquatic animals, including fish and turtles. When dams are built, a river that is already flowing becomes a lake. It becomes a lake environment when freshwater fish and turtle species seize the opportunity to multiply.
Disadvantages of Dams
- To create a sturdy basement and reservoir, large layers of dirt must be dug out during the dam’s construction. The earth’s topography is harmed by this. Because of this, earthquakes happen more frequently. However, effective engineering, design, and planning can stop such destruction.
- Dams are substantial, concrete buildings. They are not built economically.
- Dam construction necessitates a vast area. It is necessary to move the local farmers and residents to the area. Their social and economic lives are affected, and there are long-term repercussions.
- In addition to displacing people, the natural habitat is also greatly disturbed. Concerns about the flora impacted by dam construction are mostly focused on deforestation and the loss of agriculturally productive land.
- Natural wildlife that lives in the dam region is also out of control and occasionally even poses a threat to its population. To maintain their populations, breeding grounds and nesting locations are crucial. When other factors perturb these areas, their population changes.
- Bird species are disturbed, in addition to terrestrial and aquatic species.
- Fish living in freshwaters are the primary food source for migratory birds that nest on riverbanks.
- Migratory birds lose their feed and are prevented from reproducing as they do throughout the year due to the drastic shift in aquatic life caused by dam building.
- The groundwater table in the surrounding areas is decreased as a result of deepening the riverbed to create reservoirs. This has a significant negative influence on nearby, naturally occurring vegetation.
Summary
A dam is a physical obstruction that slows or restricts the flow of subsurface or surface water. Floodgates on dams can be opened or closed to allow only a small flow for human use. In recent years, irrigation for crops has primarily been provided by dams. A reservoir maintains a sizable water reserve that is mostly used to store fresh water that can be used later in times of water scarcity. Dams are substantial, concrete buildings. They are not built economically.
Frequently Asked Questions
1. Do Dams Last Forever?
Ans. A dam may be built in around ten years, and its lifespan is about one hundred years. Certain mechanical components, including motors and gates, need to be changed after a dam has been in place for 50 years. However, operational dams will undergo routine inspections. When necessary, all repairs and maintenance will be carried out right away.
2. Can we Rely Solely on Hydroelectricity to Provide our Electricity?
Ans. A renewable energy source is a hydroelectricity. Since the dam-related operation does not disrupt the water cycle, the claim that water will not run out is valid. The problem is that rivers and streams are the only sources of flowing water that dams may use. Hydroelectric power cannot be the only source of sustainably produced energy.
3. What Connection does a Dam have to Greenhouse Gases?
Ans. Large expanses of vegetation are flooded when a dam is built, submerging numerous trees. Low oxygen levels can be found near the bottom of stagnant waters in reservoirs. The reservoir’s lower layers, which are abundant in biomass, effectively release methane into the atmosphere as it breaks down.
4. What Advantages do Dams Offer to Farmers?
Ans. Large amounts of water are stored in reservoirs where they can be irrigated for use in agriculture. Croplands can also be effectively irrigated in semiarid areas far from the riverbed. Rainfall is not necessary for farmers to be able to cultivate.