Dr. Mustafa M. Aral is a Professor and the Director of Multimedia Environmental Simulations Laboratory, a research center at the School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta,Georgia, USA. He received his B.S. degree in Civil Engineering from Middle East Technical University, Ankara, Turkey, and M.S. and Ph.D. degrees from School of Civil and Environmental Engineering, Georgia Institute of Technology. His specialization area is in the fields ofenvironmental modeling, water resources engineering, mathematical, numerical and optimization methods, exposure and health risk analysis. He is a registered professional engineer in the State of Georgia with more than 35 years of research and consulting experience in environmental quality and quantity modeling, environmental fluid mechanics, optimal management of engineered and environmental systems, site characterization and health risk assessment studies. Dr. Aral has authored and co-authored more than 300 technical publications and reports. He serves as the Editor of the International Journal on Water Quality, Exposure and Healthpublished by Springer publishers and he is also an Associate Editor of several other technical journals in water resources and environmental engineering. His research work and publications has received numerous technical awards in publication excellence and research development categories from several state and federal agencies, and professional organizations. He is the principal author and developer of the ACTS and RISK software that is used in this book.