94 



Several laboratory and field studies have been carried out to evaluate 

 the Bruun Rule, usually with confirmation claimed. Schwartz (1965) 

 conducted small-scale laboratory model studies to determine whether an 

 increase in water level caused an offshore deposition equal to the rise in 

 water level as predicted by the Bruun Rule. The wave basin was quite small 

 using medium sized sand of 0.2 mm. Following the development of an 

 equilibrium profile, the water level was increased by 1.0 cm and the test 

 program resumed with the same wave conditions. Following profile 

 equilibration, it was found that the offshore profile had increased in 

 elevation by 0.9 cm which Schwartz considered as confirmation of the Bruun 

 Rule. Schwartz (1967) also conducted a second series of tests with 

 slightly larger facilities, but following the same general experimental 

 framework. Again good agreement with the Bruun Rule was reported. Field 

 measurements were also carried out by Schwartz at Cape Cod, MA in which the 

 shoreline response between spring and neap tides was evaluated in terms of 

 the Bruun Rule. Although "a recognizable upward and landward translation 

 of the profile was noted in the interval between neap and spring tides" was 

 reported and the results were generally regarded as confirmatory, 

 examination of the results is not convincing as to their significance to 

 and agreement with the Bruun Rule. Also, it is not clear that spring 

 tides, which of course have water levels both higher and lower than the 

 average, should be equated to a sea level rise since the average water 

 level is unchanged. Moreover, it is not clear that the Bruun Rule was 

 meant to apply on such a short-term basis especially recognizing that 

 short-term changes in wave climate and convergences of longshore sediment 

 transport can play an important role in beach profile changes. 



Dubois (1975, 1976, 1977) has reported on shoreline changes in Lake 

 Michigan in association with a 30 cm rise over a 35 week period. The 

 shoreline recession of 7 m was regarded as substantiation of the Bruun 

 Rule. 



Rosen (1978) has evaluated the Bruun Rule on the Virginia shoreline of 

 Chesapeake Bay. Using 14 beach profiles, Rosen found that the errors in 

 predicted erosion rates on the eastern and western shores were +58% and -7% 

 with the positive percentages indicating that the predicted erosion exceeds 



