Groundwater in Our Water Cycle
Getting to Know Earth's Most Important Fresh Water Source
Publication year: 2020
Number of pages: 136
Eileen Poeter – Colorado School of Mines, USA
Ying Fan – Rutgers, The State University of New Jersey, USA
John Cherry – G360 Institute for Groundwater Research, Canada
Warren Wood – Michigan State University, East Lansing, USA
Douglas Mackay – University of California, Davis, USA
Updated: 12 April 2021
Groundwater makes up 99% of Earth’s liquid fresh water and is vital for the sustenance of rivers, lakes, wetlands, and ecological systems. However, few people see groundwater because it is hidden beneath the land surface. To overcome this “hiddenness”, this book invites the reader to think about Earth’s fresh water in a new way, to envision that all the surface water we see in rivers, lakes and wetlands is just the tip of the Earth’s vast fresh water reservoir; that is, just the “tip of the iceberg” with the hidden portion of the “iceberg” being liquid groundwater rather than ice.
Groundwater shapes the Earth through weathering and geomorphologic processes. Rivers, lakes and wetlands are surface manifestations of groundwater, exchanging flow with the groundwater reservoir that feeds them when they need water and takes some of their flow when surface water is present in excess. This book draws attention to the ways in which the surface water that we can see is connected to and supported by the hidden groundwater reservoir that is continually flowing and replenishing the hydrologic cycle.
This continual flow of groundwater 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.
The Earth’s population of nearly 8 billion in 2020 is expected to reach 11 billion by 2100. Humans will have to learn to produce sufficient food without destroying the soil, water and climate. This has been called the greatest challenge humanity has faced. Sustainable management of groundwater is at the heart of the solution. Scientific understanding and proper management of groundwater is essential, because groundwater can alleviate the problem if we seek its responsible use and replenishment through better governance.