meeting the threshold movement were detected on the Laupahoehoe 

 breakwater. The point showing maximum magnitude for each of these 

 10 units was noted by arrows designating direction and magnitude of 

 movement on transparent overlays for the 1993 photo maps. These movement 

 vectors are shown on the photo maps displayed in Figures 21 and 22. 



When the breakwaters are reinspected and subsequent aerial flights are 

 made, this movement detection methodology will be used to determine and 

 present armor unit movement. This will allow subtle changes occurring on 

 the breakwaters, which are typically missed during normal visual breakwater 

 inspections, to be quantified. During past inspections of the older rib cap 

 areas of the Kahului breakwaters, it could not be determined whether the gaps 

 between the rib cap and armor units on the upper sea-side slope were 

 increasing or whether that was how these areas were constructed. Through 

 periodic aerial photography and application of this movement detection 

 analysis, areas in the armor unit fields that are showing movement can be 

 detected and monitored more closely to determine the probable causes of 

 changes. In some areas, motion above the waterline may indicate changes 

 occurring under the water that could be jeopardizing the structural integrity of 

 the breakwater. Also, when storms occur at a level that could result in armor 

 unit motion, these analysis methods can be applied to measure the resulting 

 changes and response of the breakwaters to tiiese storms. 



Helicopter Inspections 



In April 1992, low-level helicopter inspections were made of the Kahului 

 and Laupahoehoe breakwaters to obtain closeup 35-mm photographs. The 

 35-mm photographs, along with aerial photographs showing the approximate 

 locations of these photographs, are shown in Figures C1-C16 in Appendix C. 

 The purposes of these inspections were: (a) to provide oblique photographs 

 that could easily be viewed to gain insight into the conditions of the 

 breakwaters, and (b) to obtain a count of visible armor unit breakage. 

 Findings from the inspections and review of the 35-mm photographs and the 

 1991 stereo pairs revealed that 13, 3, and armor units were broken on the 

 Kahului West and East breakwaters and the Laupahoehoe breakwater, 

 respectively. Selected 35 mm photographs were combined with the rectified 

 photo maps to show details of armor unit breakage locations on the Kahului 

 breakwaters. These were reduced and are presented in Figures 23 and 24. In 

 September 1992, a walking inspection of the Kahului breakwaters was carried 

 out by Melby and Turk (1993) to obtain details on concrete armor unit 

 breakage for input to ongoing research being funded under work units in the 

 Coastal Engineering Research Program and the Repair, Evaluation, 

 Maintenance, and Rehabilitation Research Program. Close study of the 

 structures revealed that 28 and 1 1 units were broken on the West and East 

 Kahului breakwaters, respectively. These breakage figures, along with those 

 revealed from the aerial inspections, are presented in Table 8. 



Chapter 2 Monitoring Plan and Data 



41 



