Question

What is the benefit in construction of the Narmada Sagar project?

• A. Enhanced flood control
• B. Decrease in potential of agriculture
• C. Reduced water availability downstream
• D. Increased sediment load in the river

Hint:

• Large multipurpose dam projects like Narmada Sagar (Indira Sagar) are built with several objectives.
• Key intended benefits include:
  • Irrigation for agriculture.
  • Hydroelectric power generation.
  • Flood control by regulating river flow.
  • Domestic and industrial water supply.
• Options (b), (c), and (d) generally describe potential negative impacts or problems, not benefits.

Answer 1

The Correct Option is A

The Narmada Sagar Project (now known as Indira Sagar Project) is a multipurpose dam project on the Narmada River in Madhya Pradesh, India. Like other large dam projects, it is designed to provide several benefits, but also has associated negative impacts. The question asks for a benefit. Potential benefits of such projects typically include:

• Irrigation: Supplying water for agriculture in command areas, increasing agricultural productivity.
• Hydroelectric Power Generation: Generating electricity.
• Flood Control (option a): Dams can regulate river flow by storing excess water during peak flow periods (e.g., monsoons) and releasing it gradually, thereby reducing the risk and severity of downstream flooding. This is a significant intended benefit.
• Drinking Water Supply: Providing water for domestic and industrial use.
• Navigation, Recreation, Fisheries (sometimes): Though these can also be negatively impacted.

Potential negative impacts or challenges include:

• Decrease in potential of agriculture (option b): This is a negative impact, usually referring to submergence of fertile agricultural lands by the reservoir, or sometimes issues like waterlogging/salinization in command areas if not managed well. The aim is to increase overall agricultural potential through irrigation.
• Reduced water availability downstream (option c): Storing water in a reservoir can alter the natural flow regime and potentially reduce water availability for downstream users or ecosystems if not managed equitably or if evaporation losses from the reservoir are high. This is a negative impact.
• Increased sediment load in the river (option d): Dams typically trap sediment, leading to clearer water release downstream (which can cause riverbed erosion or "hungry water" effect) and reduced sediment supply to deltas. An increase in sediment load in the reservoir (siltation) is a problem for the dam's lifespan, but not usually an increased load in the river downstream of the dam as a benefit.

Given the options, enhanced flood control is a primary intended benefit of constructing large dams like the Narmada Sagar project. \[ \boxed{\text{Enhanced flood control}} \]