Shoreline Tracing Using Medium to High-Resolution Satellite Images for Storm Surge Modelling

Abstract:

In a developing country like Philippines, which ranks fourth in the longest coastline in the world at 36 289 kilometers, acquiring an updated and finer shoreline at the municipal level is mostly scarce. Previous studies have emphasized the importance of accurately delineating shoreline in coastal management, engineering design, sea-level rise research, coastal hazard map development, boundary definition, coastal change research and monitoring and numerical models. In the context of storm surge modelling, shoreline boundary serves as basis for tidal conditions and requires to be well-defined to generate an accurate simulation result. This paper presents the cost-effective way of shoreline tracing employed by the Storm Surge component under the Department of Science and Technology-Nationwide Operational Assessment of Hazards (DOST-Project NOAH) for use in modelling storm surge hazards in the country, particularly in San Pedro Bay during the Typhoon Haiyan. Project NOAH was tasked to conduct disaster science research and development and recommend innovative information services in government's disaster prevention and mitigation efforts through cutting edge technologies. The Storm Surge component commenced in September 2013 and was mandated by the Philippine government to identify storm surge vulnerable areas and provide high-resolution maps of storm surge inundation in the localities. In the absence of LIDAR data at the time, the Project utilized the freely available medium to high resolution satellite images of Google Earth and digitized the shoreline. To minimize subjectivity, set of digitizing standards were developed for classifying common shoreline features in the country, differentiating image textures and colors and tabulating identified shoreline features. After which, the digitized shoreline were quality checked and corrected for topology using ArcGIS Desktop 10 software. The final output is a vector data that served as boundary for topo-bathy extraction, storm surge model mesh generation, and model tidal boundary set up. Moreover, the exercise also identifies natural and engineering barriers against storm surges. The output can also be used in future projects involving those mentioned above, including building the localities’ shoreline resiliency against storm surge events.