An engaging call to understand and protect groundwater, the primary source of drinking water for almost half of the world’s population Groundwater is essential for drinking water and food security. It provides enormous environmental benefits by keeping streams and rivers flowing. But a growing global population, widespread use of industrial chemicals, and climate change threaten this vital resource. Groundwater depletion and contamination has spread from isolated areas to many countries throughout the world. In this accessible and timely book, hydrology expert William M. Alley and science writer Rosemarie Alley sound the call to protect groundwater.   Drawing on examples from around the world, including case studies in the United States, Canada, Australia, India, and Sub-Saharan Africa, the authors examine groundwater from key scientific and socioeconomic perspectives. While addressing the serious nature of groundwater problems, the book includes stories of people who are making a difference in protecting this critical resource.