(c) Sand for beach fill must be placed landward of d£ to in- 

 crease the sand supply in the intensely active littoral zone. The 

 necessary quantity of nourishment material is at least that required 

 to advance the average profile landward of d£ the desired distance. 



(d) In calculations of shoreline erosion due to sea level rise 

 over long timespans, the ocean boundary to the equilibrium nearshore 

 profile may be set at dj^. 



(e) In calculations of sediment budgets pertaining to timespans 

 less than a few decades, the ocean boundary to the control volume may 

 be set at d^ . 



(f) At sites with shore-parallel contours, subaqueous borrow or 

 disposal of material should be conducted well seaward of dn , so 

 that destructive effects on nearshore processes are minimized. Sea- 

 ward of d£ , borrow or disposal might be conducted in a region with 

 irregular contours if bottom elevations and thus shore exposure are 

 not changed significantly. 



(g) A rubble-mound breakwater should be sited in water deeper than 

 d£ for the proximate region, if its primary purpose is to provide 

 wave shelter with minimum effect as a littoral barrier. 



(h) To balance economy and function, it may be advisable to build 

 a shore-normal structure to the length corresponding to the d£ con- 

 tour for the nearby region if its primary purpose is to control 

 littoral drift. 



IV. SHOAL ZONE EXTENT ALONG U.S. COASTS 



Tables 2 and 3 present bounding water depths for the shoal zone at selected 

 U.S. coastal localities. Using the calculator program provided in the Appendix, 

 calculations for the 10 sites in Table 2 use annual summary statistics from 

 the wave climate data reported by Thompson (1977). For these sites, at least 

 1 full year of nearshore surface-piercing gage data is available, with summary 

 statistics provided by objective digital record analysis. 



Table 2. Calculated shoal zone bounds for 10 U.S. sites 

 of nearshore wave gage measiirements (Thompson, 

 feet per second squared (1 foot =■ 0.305 meter. 



using annual statistics 

 1977); y' - 1.6, g - 32. 

 1 millimeter - 0.0033 fo 



Site 





Log 



at Ion 





Hg 



J-ILL 







(ft) 



Tg 

 _(s2_ 



D 



(m,nlj 



(it) 



■^1 



Atlantic coast 













Atlantic City, N.J. 



39°21' 



N. 



, 74°25' 



W. 



2.95 



1.53 



8.6 



0.11 



11. ■i 



82.0 



Virginia Beach, V«. 



36°51' 



N. 



, 75°58' 



W. 



2.40 



l.AO 



8.3 



0.11 



19.0 



65.8 



Nags Head, N.C. 



35°55' 



N. 



, 75°36' 



W. 



3.20 



1.80 



8.8 



0.11 



24.2 



88.7 



Atlantic Beach, N.C. 



34°43' 



N. 



lb°UU' 



W. 



2.25 



1.30 



7.2 



0.12 



17.2 



51.0 



Hrlghtsville Beach, N.C. 



34°13' 



N 



77°47' 



w. 



2.60 



1.10 



7.7 



0.11 



16.3 



6C.7 



Holden Beach, N.C. 



33°55' 



N. 



78°18' 



w. 



2.05 



1.00 



7.5 



0.17 



14.4 



43.2 



Lake Worth, Fla. 



26°37' 



::. 



80°02' 



w. 



2.10 



1.15 



6.7 



0.21 



15.4 



34.8 



Gulf of Mexico coast 























Naples, Fla. 



26°08' 



N. 



zfur 



w. 



1.10 



0.75 



4.6 



0.12 



9.1 



15.8 



Destin, Fla. 



30°23' 



N, 



86°25' 



w. 



1.65 



1.05 



5.7 



0.25 



13.-. 



20.', 



Pacific coast 























Huntington Beach, Calif. 



33°39' 



U. 



U8"00' 



V. 



2.90 



1.05 



13.2 



0.11 



1_7_J1_ 



139.3 



13 



