Although many theoretical developments have been achieved inrecent years, the progress both in understanding andapplication of risk and reliability analysis in waterresources and environmental engineering remains slow. One ofthe reasons seems to be the lack of training of engineerswith phenomena of statistical nature, including optimum costand benefit decisions under uncertainty. This book presents, in a unified and comprehensive framework, the variousaspects of risk and reliability in bothwater quantity andquality problems. The topics covered include uncertaintyanalysis of water quantity and quality data, stochasticsimulation of hydrosystems, decision theory underuncertaintyand case studies. Methods for risk analysis ofextremes in hydrology, groundwater clean-up, river andcoastal pollution as well as total risk management arepresented.