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Field Survey Techniques 



The most direct and accurate means of assessing geomorphic variability is 

 to conduct periodic surveys for the express purpose of obtaining time-series 

 data. However, as a practical matter it is usually not feasible to carry out 

 repeated surveys for a sufficient length of time for reliable and comprehensive 

 information because of expense and because the lead time for projects often 

 does not allow sufficient time to obtain the needed data. Nonetheless, a set of 

 surveys spanning over a year or more can be of substantial help in learning 

 more about the prevailing seasonal changes. 



Field surveys of coastal features show that the most active zones are the 

 shore and upper shoreface. Submerged interior parts of previously subaerial 

 features, such as relict shore and dune deposits formed during earlier stages of 

 development, are distant from the modern shoreline and are likely to be 

 affected by marine or lacustrine processes only during large storms. Large- 

 scale aerial photographs and topographic maps of these interior areas are 

 usually available and are adequate for study purposes. 



Information on the active, more variable shore and shoreface zones is 

 usually obtained by direct field survey. The preferred surveying technique 

 involves collecting a series of shore-normal profile lines. The profile lines 

 should extend landward of the influence of inundation by moderate storms, 

 usually behind frontal dunes. The preferred closure depth is at the toe of the 

 shoreface, often defined as a selected depth contour where variability becomes 

 minimal. Profile lines should be spaced at intervals close enough to show any 

 significant changes in lateral continuity. Profile lines are connected with a 

 surveyed shore-parallel baseline from which position and elevations of each 

 profile origin can be determined. 



Resurveying control profile lines at selected intervals of time can reveal 

 seasonal patterns. In addition, special surveys can be made after significant 

 storms and events to determine whether these events affect the local beach 

 system. As previously noted, however, lead time and expense do not usually 

 allow for an extended period of monitoring profiles. At a minimum, summer 

 and winter profiles are recommended to identify seasonal variability. 



A permanent or semi-permanent benchmark, or set of benchmarks, is 

 required for reoccupying a profile site over successive months or years. On a 

 rapidly transgressing coast, these benchmarks should be located near the 

 landward end of the profile line in order to minimize storm damage, although 

 locations which might experience dune burial should be avoided. On a 

 regressive coastline, the benchmarks can be placed closer to the shoreline. In 

 both cases, care should also be taken to reduce the visibility of benchmarks so 

 that they will not be damaged by vandals. 



Chapter 5 Investigation of Geomorphic Factors 



