Determining large scale sandbar behaviour

To study the morphology of coastal sandbars and their change with time, it is necessary to obtain a sequence of maps over the period of interest. Traditional techniques such as vertical aerial photography or echo-sounding over a grid are expensive and subject to environmental constraints, especially in higher energy situations. Image processing is used to rectify elevated terrestrial images where morphological features are inferred from breaking wave patterns. As the coordinates of interest are longshore and offshore distances, the image is then warped to make the coastline straight. The sandbar crest positions within this image are detected. An error analysis shows that useful quantitative data may be obtained. The temporal evolution of the bars can be identified from time stack images.