Table 3 



Overtopping for 1978 Storm at Profile 2 for Prototype Seawall 



Length of 3,890 ft 



Hour 



Interp 

 Hour 



Begin 

 Hour 



End Hour 



Total 

 Time 

 sec 



Overtopping 

 Rate, cfs/ft 



Acre-ft for 



3,890-ft 



Length 



13 



13.29 



12.50 



13.64 



4,094 



0.0097 



3.56 



14 



13.98 



13.64 



14.49 



3,077 



0.0994 



27.32 



15 



15.00 



14.49 



15.44 



3,421 



0.5200 



158.88 



16 



15.88 



15.44 



16.73 



4,642 



0.1659 



68.76 



17 















18 



17.58 



16.73 



18.50 



6,366 



0.0103 



5.86 



25 



25.34 



24.50 



25.74 



4,458 



0.0100 



3.97 



26 



26.13 



25.74 



26.82 



3,879 



0.1674 



57.99 



27 



27.50 



26.82 



27.50 



2,463 



0.8141 



179.08 



28 



27.50 



27.50 



28.30 



2,888 



0.8141 



209.93 



29 



29.10 



28.30 



29.55 



4,500 



0.1359 



54.60 



30 



30.00 



29.55 



30.50 



3,412 



0.0116 



3.54 



Storm Total 



773 acre-ft 



of overtopping over the seawall for the time period that was tested. For 

 this series of tests, NED determined that 3,890 ft of seawall would contrib- 

 ute to the flood zone. Overtopping rates and volume for each hour of the 

 storm are shown in Table 3. 



Based on surveys of high-water marks, NED calculated that about 

 600 acre-ft of water overtopped the seawall during the 1978 storm. The 

 physical model test showed a total overtopping of 773 acre-ft, roughly 

 29 percent higher than the surveys had indicated. Due to uncertainties in 

 the surveyed results, numerical models, and physical model tests, test re- 

 sults were surprisingly close to the predicted results. Uncertainties in the 

 tests are discussed in Chapter 4, "Discussion of Research Tasks A, B, and 

 C." 



Chapter 3 Research Tasks A, B, and C 



15 



