What is the function of an aquitard?

An aquitard serves as a significant geological formation that consists of materials which have low permeability, such as clay or silt. Its primary function is to act as an impermeable layer that restricts the movement of water between aquifers. This characteristic helps to protect the water within an aquifer by preventing the contamination from surface pollutants and controlling the rate at which groundwater can flow.

The presence of an aquitard is crucial for maintaining the integrity of aquifers. It can effectively separate different layers of groundwater systems, allowing for the storage of water in the underlying aquifer while limiting the interaction with others. While the other options pertain to aspects of water management or storage, they do not accurately describe the specific role of an aquitard in the hydrological cycle.