12r 



Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 

 (Mo) 



Figure 33. Cumulative volume of sand on Ludlam Beach, 

 based on a 10-year monthly average. 



The periods of minimum and maximum sand volumes on Ludlam Beach were 

 November through May and June through October, respectively. The positive 

 month-to-month change (Fig. 33) in May, June, and July was greater in magnitude 

 than the negative change in volume between months in the fall and winter. The 

 largest average monthly changes in sand volume above MSL were accretional (5.3 

 cubic yards per foot-month during June, Fig. 33). The maximum monthly loss 

 rate was 4.4 cubic yards per foot -month in August. The monthly data were widely 

 scattered. Each year did not exhibit the seasonal exchange trend shown in 

 Figure 33 which is the average of one mode of oscillation of sand storage on 

 the beach. Consequently, the seasonal losses and gains should be considered 

 more of a tendency than a cycle. 



A plot of the mean monthly shoreline position is similar to the volume 

 changes shown in Figure 33. The mean range between maximum retreat and advance 

 was 50 feet. 



When mean monthly changes in sand volume and shoreline position were plotted 

 by profile line (Fig. 34), several variations were observed. For example, be- 

 tween April and May sand eroded at Corson Inlet and accumulated at Townsend 

 Inlet. From June to July the direction of the changes reversed at the two 

 inlets. From September through December the monthly changes near Corson Inlet 

 were also opposite in sign to those at Townsend Inlet. 



Based on a referenced zero sand volume on the beach on 1 January, the mean 

 cumulative sand volume for each profile line, obtained by averaging all volumes 

 obtained by surveys for that month, is shown in Figure 35. As shown, the sand 

 volume maximums and minimums generally occur at about the same season on all 

 profile lines. An exception occurs between profile lines 8 and 13, just north 



47 



