(1) Draw the groin profile on the original beach profile. 



(2) Draw the MLW or MLLW line. 



(3) Locate the berm crest position relative to the HSS part of the 

 groin. Label this point a. For example, point a can be, but is not 

 limited to, one of the points r, s, t, or u from Figures 5-14 to 5-17. 



(4) Draw a line parallel to ^ibi (the natural above low water level 

 beach slope) from the berm position, point a, to the intersection with the 

 MLW or MLLW line, point b. 



(5) Connect the intersection of the slope line and the MLW or MLLW 

 line, point b, with the intersection of the groin end and the natural beach 

 profile, point c. 



Groin -Adjusted 

 Beoch Profile;, 



Note : Line a b 



Parallels a, b, 



Original 

 Beach Profile 



Figure 5-20. Determination of beach profile adjacent to groin, 

 *************** EXAMPLE PROBLEM 4*************** 



GIVEN ; A groin design as follows: The HSS is to be built to the natural berm 

 elevation of +2.5 meters (+8.2 feet) MLW and will extend from 40 meters 

 (131.2 feet) shoreward to 50 meters (164.0 feet) seaward of the present berm 

 crest. The OS is to be built at MLW elevation and will extend to a depth of 

 1.5 meters (4.9 feet) below MLW. The beach can be approximated by a 1 on 

 10 slope from the berm crest to MLW and a 1 on 50 slope from MLW seaward. 

 The beach alinement analysis predicts that the berm crest on the downdrift 

 side of the groin will erode 20 meters (65.6 feet) shoreward of the present 

 position (see Fig. 5-21). 



40m 



/ 



Crest of Berm 



20m 



50 m 



IPredictedLflerm (Ele>. 2.5m) h^^ 



Adjusted 

 Downdrift Beocti 



Profile 



^ Oriqinol Beocti 

 \J^ Profile 



Groin 



N to 





Elev. -1. 5m 



Figure 5-21. Downdrift profile design in example problem. 



5-49 



