Define the following formations in regard to hydrology: 1. aquitards, 2. aquicludes, 3. aquifuges.

1. Aquitards: Aquitards are formations that have low permeability and restrict the flow of water. They act as barriers to the movement of groundwater and can slow down or prevent the movement of water between aquifers.

2. Aquicludes: Aquicludes are formations that have very low permeability and do not allow the flow of water. They act as complete barriers to the movement of groundwater and prevent the movement of water between aquifers.

3. Aquifuges: Aquifuges are formations that are impermeable and do not allow the flow of water. They act as complete barriers to the movement of groundwater and prevent the movement of water between aquifers. Aquifuges are typically composed of materials such as clay or bedrock that do not allow water to pass through.

1. Aquitards

- Formations that allow a slow but significant rate of groundwater flow.
- Permeable but with low hydraulic conductivity (K) compared to aquifers.
- May impede groundwater flow between aquifers or act as confining layers.
- Examples: Clayey silts, silty clays.

2. Aquicludes

- Formations that do not allow groundwater flow.
- Impermeable and have extremely low hydraulic conductivity.
- Act as barriers to groundwater movement.
- Examples: Granite, massive clay formations.

3. Aquifuges

- Formations that lack both permeability and porosity.
- Groundwater cannot flow through or be stored within them.
- Examples: Igneous and metamorphic rocks (e.g., granite, schist).