A variety of optimization and simulation models are now com- monly used to help water resource planners and managers identify, evaluate and predict themultiple impacts from va- rious actions or decisions one can make regarding the deve- lopment and management of a region's water resources. Cur- rent developments in computer technology are making it pos- sible to link these models to programs that provide an in- terface betwe- en the decision maker and their models and compu- ters. The volume discusses how these so-called deci- sion support systems can be best developed and used bythose involved in water resources planning and management.