7 The Unique Functions of Groundwater in Earth’s Hydrologic System
The groundwater compartment of the hydrologic cycle is a large, slow moving reservoir of fresh water (in its shallower realms), that reacts chemically with geologic materials along its flow paths, and interfaces with the water transport systems of rivers and the atmosphere. This vast groundwater reservoir serves as: 1) a regulator of the fresh‑water hydrologic cycle by mediating the flow of continental surface waters; 2) a chemical factory and conveyor belt for processing Earth’s material and transporting it from the continents to the oceans; 3) a waste repository/processing plant; and, 4) a global life‑support system.