The correct answer is D. All of the above.
Multi-purpose river projects are designed to achieve multiple objectives, such as irrigation, power generation, flood control, and navigation.
Irrigation is the process of artificially adding water to soil to assist in the growth of crops. Dams are often constructed to store water for irrigation purposes. The water stored in a dam can be released slowly and evenly throughout the growing season, which helps to ensure that crops have enough water to grow.
Power generation is the process of converting mechanical energy into electrical energy. Hydroelectric power plants use the energy of moving water to generate electricity. Dams are often constructed to create reservoirs, which are large bodies of water that are used to store water for hydroelectric power generation.
Flood control is the process of preventing or reducing the damage caused by floods. Dams can be used to control floods by storing water during the rainy season and releasing it slowly and evenly during the dry season. This helps to prevent flooding downstream of the dam.
Navigation is the process of moving ships and boats from one place to another. Dams can be used to improve navigation by creating a deeper channel for ships to travel through. This can make it easier for ships to transport goods and people.
In conclusion, multi-purpose river projects are designed to achieve multiple objectives, such as irrigation, power generation, flood control, and navigation.