The purpose of this study is to estimate shoreline positions from X-band radar echo images. Based on the principle and mechanism of radar echo signals, the time-averaged and standard deviation statistics of radar echo intensities can highlight the different characteristics of the sea and land. Therefore, this study proposes a set of processing procedures for the measurement of shoreline positions using X-band marine radar. The proposed technique integrates an image filter, thresholding, edge detection, and a morphological method, which are used to determine the shoreline positions at the land-water interface. In order to assess the feasibility of the proposed method, the obtained shoreline positions are compared with those in an optical image from an unmanned aerial vehicle (UAV). It was found that the shoreline positions measured from radar images agree with those visually identified from UAV orthoimages. The shoreline positions derived from time-averaged radar images were compared with those derived from standard deviation radar images. The results show that shoreline measurements using time-averaged radar images are more suitable than those using standard deviation radar images under calm wave conditions, and that the former are unaffected by sea surface conditions. Therefore, time-averaged radar images were selected for shoreline measurements to discuss shoreline variations at the southern sandy coast of Anping commercial port in Tainan during various periods, and to demonstrate the practicability of the proposed method. The advantage of coastal shoreline monitoring with X-band radar is that can provide real-time and uninterrupted observation, even in bad weather conditions. Therefore, the temporal and spatial variations of a shoreline can be automatically and continuously monitored over the long term to help authorities understand coastal changes, facilitating coastal protection and sustainable development in coastal zones.
|Date of Award||2018|