Table 5. Dates of aerial photo missions at Ludlam Beach. 



Overflight 



Predicted 



Dat 



e 



Overflight 



Predicted 



Date 





time 



low tide 







time 



low tide 







1155 



1618 



26 Apr. 



1974 



1 



1346 



24 Mar. 



1963 



1125 



1147 



23 Apr. 



1971 



1235 



1334 



4 May 



1962 



1220 



1317 



7 Mar. 



1970 



1410 



1512 



8 Mar. 



1962 



1045 



1153 



23 Oct. 



1969 



1320 



1126 



22 Sept. 



1961 



0950 



1059 



13 Apr. 



1969 







1123 



7 June 



1960 



1210 



1247 



12 Apr. 



1968 







1244 



22 Apr. 



1959 







1241 



9 Jan. 



1967 







1015 



29 May 



1958 







1305 



4 May 



1966 







1309 



21 Nov. 



1957 







1243 



14 May 



1965 







1106 



30 Apr. 



1954 







1153 



10 Apr. 



1964 







1339 



10 May 



1952 











.... 



1254 



21 Oct. 



1949 



^Not available. Most photos were obtained at low tide. 



were road junctions observed on both the 1949 and the 1974 aerial photos. Road 

 junctions were located in sufficient density near the beach so there were at 

 least three easily locatable reference points on the base map per photo. The 

 road junctions were near the average elevation of the island, which minimized 

 relief displacement errors. The scale of the base map was slightly expanded 

 to 1:9096 so all aerial photo scales would be smaller. 



b. Quality Control . Stafford (1971) discusses errors inherent in aerial 

 photos that can lead to misinterpretation. Because photos in this study were 

 largely made under the same conditions, and because sand elevation differences 

 on Ludlam Beach were less than 20 feet, such errors were minimized. Where 

 measurements were compared, differences between repetitions were less than 10 

 percent of the differences measured between separate flights. Thus, errors in 

 tracing images on the base map and in making the required measurements, were 

 assumed acceptable. 



IV. ANALYSIS AND RESULTS 



The behavior of beach material on Ludlam Beach during the survey period 

 (1962-72) was highly variable from profile line to profile line, and between 

 surveys. However, when the survey data were averaged, such as by month, year, 

 or by profile line, consistent trends in beach change appeared. Beach survey 

 information data from the aerial photo analysis and wave data provided informa- 

 tion on when, where, and how much beach material was eroded and deposited, and 

 in what direction it was transported. The survey data also provided information 

 on temporal and spatial changes in the position of the shoreline. (See App. A 

 for the definitions of terms used in the analysis.) 



1 . Shoreline Shape . 



Ludlam Beach is the middle of five barrier islands south of Absecon Inlet 

 in New Jersey, each of which exhibit a characteristic concave seaward shoreline 

 (Fig. 1). The shoreline protrudes seaward near inlets on either end of these 



34 



