By definition, shorelines (also called water’s edges) are lines that demark the exact boundary between water and land. The position of the shoreline changes regularly as the level of water tides change and as a result, they are said to be impermanent topographic features. Erosion and man-made processes near the water bodies (rivers, lakes and oceans) have effects of altering the structure of the shorelines and as such, they are known to be short-term geologic features. This discussion aims to look at how man-made, tidal and erosion processes contribute to shorelines being short-lived topographic and geologic features.
The position of water edge during high tide is distinct from its position during low tide because the location of the water shifts with tidal elevation. In addition, the continuous nature of tidal processes that are characterized by fall and rise of the tide indicates that there is infinite number of shorelines. As a result, it is not possible to draft a permanent topographic map of the shorelines since the tidal processes make them short-lived topographic features (Bird, 2008, p.40).
On the other hand, agents of erosion and man-made activities in the shores alter the structure of water's edges making them temporary geologic features. Agents of erosion destruct the shape of shorelines as they take away some of the sand or soil making up the shoreline and deposit it either inside the water bodies or to some other position in the shoreline. The agents also carry sediments from land surfaces to deposit it onto the shorelines. Man-made activities such as shoreline armoring, inlet dredging or stabilization and construction near the shores deplete sand or soil from the shorelines. In effect, all these processes and activities have an effect of altering the structure of the shorelines (Bird, 2008, p.202). Thus, shorelines are said to be short-lived geologic structures.
In conclusion, water's edges are impermanent geologic structures because of erosion processes and man-made activities in the shores. They are known to be short-lived topographic structures because of tidal processes that are characterized by rise and fall of water tides.