In hydrology, what is an aquiclude?

• A. Border between the water holding areas
• B. Layer of rock that allows water to flow freely
• C. A zone of high porosity
• D. A permanent body of underground water

Answer: (A)

An aquiclude is best defined as a geological layer that prevents the passage of water, effectively acting as a barrier between water-holding areas. This means that while it may lie adjacent to an aquifer, it does not allow the movement of groundwater through it. The presence of an aquiclude can significantly impact the hydrology of an area by confining aquifers, leading to the creation of pressure within the water-bearing layers and influencing how water is stored and transmitted underground.

In contrast, the other options describe different geological concepts that do not accurately represent the characteristics of an aquiclude. For example, a layer of rock that allows water to flow freely pertains to an aquifer, while a zone of high porosity describes a type of material conducive to storage rather than blockage. Finally, a permanent body of underground water usually refers to a groundwater reservoir, not to a rock layer that restricts water movement. Therefore, identifying an aquiclude as a border between these water-holding areas captures its function accurately in the context of hydrology.