Which of the following best explains how overpumping of groundwater in coastal areas leads to water scarcity?

• A. Overpumping has no effect on water availability in coastal areas.
• B. Overpumping increases rainfall, which dilutes the groundwater and improves water quality.
• C. Overpumping causes groundwater to become more abundant due to increased underground flow.
• D. Overpumping lowers the water table, allowing saltwater to intrude and contaminate freshwater supplies.

Answer: (D)

Verified step by step guidance

1. Understand the concept of groundwater and its role in providing freshwater in coastal areas. Groundwater is stored in aquifers beneath the earth's surface and is a crucial source of freshwater for many communities.
2. Recognize that overpumping groundwater means extracting water faster than it can be naturally replenished. This leads to a lowering of the water table, which is the upper surface of the groundwater.
3. In coastal areas, the freshwater in aquifers normally sits above denser saltwater from the ocean, creating a natural barrier that prevents saltwater from moving inland.
4. When overpumping lowers the water table, this natural barrier weakens, allowing saltwater to intrude into the freshwater aquifer. This process is called saltwater intrusion.
5. Saltwater intrusion contaminates the freshwater supply, making it unsuitable for drinking and irrigation, thereby causing water scarcity despite the presence of groundwater.