"The ability of a material to allow the passage of a liquid, such as water through rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them, whereas unpermeable material, such as clay, don't allow water to flow freely." (U.S. Geological Survey, 2019)


U.S. Geological Survey (USGS). "Water Science Glossary Terms". USGS Water Science School. (2019). Link: