3 Summary 



By means of limited land surveys, low-level helicopter inspections with 35- 

 nmi photography, aerial photography, and photogrammetric analysis, base 

 conditions have been established for the Kahului and Laupahoehoe 

 breakwaters. Accuracy of the photogrammetric analysis techniques has been 

 checked through comparison of ground and aerial survey data on armor units 

 that had been specifically targeted and surveyed for this purpose. A method 

 using high-resolution, stereo pair aerial photographs, a stereoplotter and 

 AutoCAD files, has been developed and tested to analyze the entire above- 

 water armor unit fields to quantify armor unit movement that exceeds a 

 threshold value of 0.5 ft. During testing of the method, it was observed that 

 very little change, in regard to armor unit movement, occurred during the 

 1991-1993 monitoring, but this should be anticipated, as the wave climate to 

 which the structures were exposed was very mild during this time period. 

 Low-level helicopter surveys of concrete armor units revealed no breakage on 

 the Laupahoehoe breakwater and only minimal amounts of breakage on the 

 Kahului structures. A walking inspection of the Kahului breakwaters 

 conducted under another research study revealed higher levels of armor 

 breakage than found by aerial studies. The level of breakage is still minimal, 

 but the area at the confluence of the sea-side of the head and trunk of the west 

 breakwater is beginning to show a slight concentration, or cluster, of breakage 

 and this area should be monitored more closely than other areas. Also, the 

 land-based breakage survey revealed that the accuracy of aerial breakage 

 inspections can be questionable and that for more accurate armor unit 

 breakage counts, detailed walking inspections should be conducted over the 

 armor unit fields. 



Now that the base (control) conditions have been defined at a point in time 

 and a method has been developed to closely compare subsequent years of 

 high-resolution aerial photography of the Kahului and Laupahoehoe 

 breakwaters, these sites will be revisited during future years under the 

 Periodic Inspections work unit to gather data by which assessments can be 

 made on the long-term response of the structures to their environment. 

 Insight gathered from these efforts will allow definite decisions to be made 

 based on sound data as to whether or not closer surveillance and/or repair of a 

 structure is required to reduce the chance that it will fail catastrophically. 



Chapter 3 Summary 



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