Foreword

Groundwater pumped from aquifers provides half of the world’s population with drinking water and supports global food production by serving 38% of the world’s irrigated lands. Of all groundwater withdrawn around the globe, 70 percent is used for agricultural production of food, fibers, livestock and industrial crops. Humanity depends on this important natural resource now and increasingly so as the global population rises from 8 to 10 billion people over the next few decades. To be informed citizens of the global community at this point in human history, when the global population is still ballooning and continents are drying as aquifers are depleted while drought is expanding, we need to be more aware of the role of groundwater and its importance to our well-being.

There are aquifers nearly everywhere in the world. They range in size from those with an area less than a soccer field and thinner than a two-story building to mega aquifers, which are more than a thousand kilometers across and hundreds of meters thick. Some are buried deep below low permeable strata that are not water-bearing (aquitards) while others are shallow, just below the ground surface. This book presents an overview of the world’s 37 mega aquifer systems and discusses their state and relevance. These 37 aquifers represent more than half of the world’s groundwater reserves, account for approximately 40% of the total volume of global groundwater withdrawal, and cover areas in 57 countries of the world on six continents.

This book presents key information about mega aquifers to provide a perspective on each related to its hydrologic circumstances. Appropriate background reading for this book includes the following Groundwater Project books: Groundwater in Our Water Cycle, Hydrogeologic Properties of Earth Materials and Principles of Groundwater Flow, and Groundwater Resources Development.

This book was authored by Jac van der Gun, a Dutch groundwater hydrologist and water resources specialist who is one of the few people qualified to address this topic. He has been engaged in this subject matter for over half a century with hands-on experience in many countries on four continents.

John Cherry, The Groundwater Project Leader
Guelph, Ontario, Canada, June 2022