Geographic Information System in Managing Flood Protection

Abstract

Geographic information system (GIS) is a very powerful tool in data preparation, management, manipulation, analysis and presentation.  GIS is used in almost all applications.  Quantum Geographic Information System or QGIS is free and open-source software.  In this study, positions obtained from a mobile mapping system (MMS) were input to QGIS program to demonstrate how to manage flood protection.  King Kaeo Road, a southern part of the King’s Dyke in the east of Bangkok, was selected as an example for displaying the result of mobile mapping system (MMS) processing and analyzing the causes of inadequate satellite signals to compute the accurate (±5 centimeters) positions.  Google map, Google satellite and OpenStreetMap were plug-in to QGIS program. From displayed map, points outside the King’s dyke were eliminated and the gaps (of inaccurate positions) could be seen. To fill in small gaps caused by pedestrian overpasses, missing positions could be interpolated or approximated. Repeating MMS data collection at different satellite geometry could remedy the missing positions in some areas.  The last recommendation to complete all needed positions along the dyke was to use a ground survey by differential and profile leveling.  Using MMS to collect the data and QGIS to help analyzing the result was the most effective and rapid method to create the data base for managing flood protection.