Question

which of the following statements explains how coastal flooding results in increased salinity of ground water supplies?
multiple choice
as salt water is less dense than fresh water when there is coastal flooding the salt water floats to the top of the aquifer.
coastal flooding results in rivers and lakes filling with salt water, which leads to ground water contamination with salt.
ground water supplies fill as a result of coastal flooding which leads to more salts being dissolved from the surrounding rocks.
when aquifers are depleted this creates space that is filled with salt water that comes in with coastal flooding.

Explanation:

• Salt water is denser than fresh water, so the first option is incorrect.
• Coastal flooding doesn't directly fill rivers and lakes with salt water in the way described in the second option.
• Dissolving salts from surrounding rocks due to flooding is not the main reason for increased groundwater salinity in this context.
• When aquifers are depleted (e.g., over - pumped), they create voids. Coastal flooding can then push salt water into these depleted aquifers (as salt water can move into the space where fresh water was removed), which explains the increased salinity.

Answer:

When aquifers are depleted this creates space that is filled with salt water that comes in with coastal flooding.