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5 Investigation of Geomorphic 

 Factors 



Nature of Geomorphic Changes 



Techniques for investigating geomorphic features and coastal evolution can 

 provide useful information for coastal engineering design. Such techniques 

 can include field surveys, analysis of historical maps and aerial photographs, 

 airborne remote sensing, waterborne remote sensing, and sedimentologic and 

 stratigraphic techniques depending on the spatial scale and the time scale of 

 the data needed. Collection and comparative analysis of time series data 

 showing dimensions, elevations, and configuration of coastal features over an 

 extended period of time are effective ways of identifying temporal geomorphic 

 changes and trends. In most cases, the use of multiple techniques will provide 

 a useful balance of information regarding a site. 



At the interface where marine and lacustrine processes interact with the 

 land, coastal features are highly variable. For effective management, cyclic 

 patterns, intermittent noncyclic events, and long-term trends must be 

 considered. In mild weather, the morphological changes that take place on a 

 day-to-day basis are relatively small and often compensate for each other, so 

 that little net effect is apparent. During storms, a wider zone of the coast may 

 be exposed to coastal processes and large geomorphic changes can occur in 

 only hours or days. 



In many places, distinct changes in coastal geomorphic features occur on a 

 seasonal basis. A common example is a winter-summer cycle, in which 

 winters are times of more intense and frequent storms than the summer 

 seasons. An example of seasonal cycles in coastal morphology is the changes 

 that occur in beach profiles. The more severe wave climate of winter causes 

 erosion of the shore, with the eroded material usually transported seaward to 

 the upper shoreface, where it often forms submarine bars. With the return of 

 milder conditions in the summer months, this sand usually returns to the beach 

 and a period of milder weather prevails. This cycle may be interrupted by 

 hurricanes in summer and early fall, which greatly disrupt the normal summer 



Chapter 5 Investigation of Geomorphic Factors 



