The hyporheic zone is a region beneath and alongside a river or stream where surface water and groundwater mix. This area plays a crucial role in the ecosystem by filtering pollutants, providing habitat for various organisms, and supporting nutrient cycling. It is typically found in the sediments beneath the riverbed. In the hyporheic zone, water flows slowly through the soil and sediment, allowing for interactions between aquatic and terrestrial environments. This zone is essential for maintaining water quality and supporting biodiversity, as it serves as a refuge for species like invertebrates and microorganisms that contribute to the overall health of river systems.