High resolution digital elevation model and a Web-based client-server application for improved flood plain management

Digital elevation models (DEMs) are used more and more frequently in flood plain management. Examples include flood plain models, visualization, flood hazard assessment, and determination of flood-plain elevation. One of the major problems in developing accurate high resolution DEMs is that traditional data sources do not possess enough horizontal resolution and vertical accuracy for flood-plain studies. In this study, a high-resolution DEM was generated using digitally scanned NAPP aerial photos in conjunction with highly accurate ground control from a rapid-static GPS survey. The high resolution DEM and an ortho-mosaic of the NAPP images developed in this study were made available to St. Charles County government officials through the World Wide Web using Client-Server technology. The design and development of this technology utilized ArcViewIMS, ArcView GIS, Java, JavaScript, HTML and Avenue programming. This Web-based tool allows the user to query a point in the ortho-mosaic to determine horizontal position and vertical elevation. In addition, common mapping functions such as zoom, pan, download and print are also incorporated in the Web-based tool