dams advantages and disadvantages .pptx

A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions.

The word dam can be traced back to Middle English,[1] and before that, from Middle Dutch, as seen in the names of many old cities,[2] such as Amsterdam and Rotterdam.

Ancient dams were built in Mesopotamia and the Middle East for water control. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. Egyptians also built dams, such as Sadd-el-Kafara Dam for flood control. In modern-day India, Dholavira had an intricate water-management system with 16 reservoirs and dams. The Great Dam of Marib in Yemen, built between 1750 and 1700 BC, was an engineering wonder, and Eflatun Pinar, a Hittite dam and spring temple in Turkey, dates to the 15th and 13th centuries BC. The Kallanai Dam in South India, built in the 2nd century AD, is one of the oldest water regulating structures still in use.

Roman engineers built dams with advanced techniques and materials, such as hydraulic mortar and Roman concrete, which allowed for larger structures. They introduced reservoir dams, arch-gravity dams, arch dams, buttress dams, and multiple arch buttress dams. In Iran, bridge dams were used for hydropower and water-raising mechanisms.

1. What is a Dam? A D am is   a structure built across a river, stream, or waterway to control the flow of water.

2. Advantages of Big Dams

3. >> Power Generation

4. >> Crop Irrigation

5. >> Flood Control through Dams

6. >> Economy Developement

7. Disadvantages of Big Dams

8. >> Dam Failure

9. >> Sediment Capture

10. >> Fish Declination

11. >> People Migration

12. Environmental Impact of Dams

13. >> Disruption of Ecosystems Dams alter natural water flow, which can disrupt local ecosystems. Aquatic species that depend on specific water conditions for spawning or migration may suffer. For instance, fish species may be blocked from migrating to breeding grounds, affecting biodiversity >> Water Quality Degradation The creation of reservoirs behind dams can lead to stagnation, which reduces oxygen levels in the water. This can lead to the growth of harmful algae blooms, water contamination, and a decrease in water quality for surrounding communities and wildlife.

14. >> Loss of Biodiversity By flooding large areas of land to create reservoirs, dams can destroy habitats for wildlife, including forests, wetlands, and grasslands. This loss of habitat can lead to the decline or extinction of some species . >> Greenhouse Gas Emissions While dams are generally seen as clean sources of energy, large reservoirs in tropical regions can lead to the decomposition of submerged organic material, releasing methane, a potent greenhouse gas.

15. ZONATION OF LAKES

16. Any questions to be asked?