Franklin W. Schwartz, PhD, is Professor and Ohio Eminent Scholar in Hydrogeology at The Ohio State University in Columbus. He is the co-author of Fundamentals of Groundwater and Physical and Chemical Hydrogeology. His research interests include groundwater sustainability, geo-environments and health, and water and societies. Hubao Zhang, PhD, is a software engineer at Rain Bird. He has extensive experience working in environmental consulting and groundwater modeling and is the co-author of Fundamentals of Groundwater.