The excessive extraction of sand and gravel from riverbeds in Punjab can lead to:

The correct answer is: d) All of the above

Excessive extraction of sand and gravel from riverbeds can lead to a number of problems, including:

• Ecological imbalance: Sand and gravel are essential for the health of river ecosystems. They provide habitat for fish and other aquatic life, and they help to regulate the flow of water. When sand and gravel are removed from riverbeds, it can disrupt the natural balance of the ecosystem. This can lead to problems such as fish kills, changes in water quality, and the loss of riverbank vegetation.
• Riverbank erosion: Riverbanks are naturally eroded by the flow of water. However, excessive extraction of sand and gravel can accelerate this process. This can lead to the collapse of riverbanks, which can damage property and infrastructure. It can also increase the risk of flooding.
• Lowering of the water table: Sand and gravel act as a filter for water. When they are removed, it can allow water to flow more easily through the soil. This can lower the water table, which can have a number of negative impacts, including:
  • Reduced water availability for drinking, irrigation, and other uses
  • Increased risk of drought
  • Increased soil erosion
  • Damage to wetlands and other ecosystems

In conclusion, the excessive extraction of sand and gravel from riverbeds can have a number of negative impacts on the environment. It is important to manage sand and gravel resources sustainably to avoid these problems.