Identification of onshore features for delineation of the land water interface and their spatial-temporal variation using high resolution imagery

High water mark (HWM) line is accepted as the most landward of the cadastral boundaries between water and land. Only limited research has been done to determine the horizontal location of HWM accurately because of the spatial and temporal variation of its location. In this study, different HWM indicators, such as vegetation lines and sudden change of slope (SCoS) are defined and realized using an object-oriented image analysis (OOIA) approach. An evaluation model is introduced to access the spatial and temporal variation of different HWM indictors based on their consistence and stability. The methodology and results of a case study in South Fremantle, Western Australia, are presented. The study shows that the height of Highest Tide Recorded (HTR) was the most stable and consistent indicator when positioning on the ground and as a consequence is suggested as an appropriate HWM location.