Hydrodynamic Agents in the Littoral Environment. Phase 1 Progress Report

Abstract : Hydrodynamic Agents in the Littoral Environment (HALE) is a National Geospatial-Intelligence Agency program aimed at producing tidal predictions from imagery-derived water levels. HALE has been divided into three phases which lead to a protocol. This report describes Phase I and introduces work for Phase II. Approximately 62 satellite images of the Han River Estuary, Republic of Korea, over the 20-year period from 1987 to 2006 were processed and analyzed. The fundamental procedure involved semi-automated extraction of waterlines from high-resolution commercial imagery. Rules such as application of a red-edge index are used in quality controlling waterlines, estimating the extend of mudflats, and assessing shoreline changes due to erosion and/or sedimentation. Elevations were estimated using waterlines and a high-precision Digital Elevation Model (DEM). Elevations are determined from the intersection of the waterline with a beach profile derived from the DEM. Favorable locations have a flat gradient allowing any transects to be extended below Mean High Water (MHW). Analyses highlight the importance of shallow water tidal constituents and the utility of seasonal DEMs. Subsequent work during Phase II will focus on time series analysis involving the use of random water elevations corresponding to simulated imagery for Seward, Alaska.