This dissertation introduces FESM (Flood Event Simulation Model), a Geographic Information System (GIS) tool designed for use on gaged river systems that can be used to guide logistic support during disaster events. FESM rapidly generates flood predictions using elevation data from real-world sensors or generated by other models. Verification and validation data for FESM are provided. In order to construct a visualization system for interacting with FESM outputs, single buffer and dual buffer techniques for moving massive datasets to the GPU for processing using OpenCL were rigorously tested and timed, and an analysis of the costs/benefits of using buffers or images was conducted. Finally, DRO (Dynamic Raster Overlay), a visualization system for analysis of datasets composed of multiple overlapping flood maps is introduced, and expert feedback is provided on the effectiveness of DRO with selected case studies.