Modeling Beach and Nearshore Profile Response to Lake Level Change

Design of beach and nearshore change models entails a thorough understanding of the complex physical processes involved and the proper application of appropriate simplifying concepts. A large set of beach and nearshore profile data from southern Lake Michigan has been used to evaluate the widely applied equilibrium profile concept. Results of this study show that the profile form h = Ax m is appropriate for use in describing the average profile found in southern Lake Michigan. Although values for the coefficient m varied over a range from 0.3 to 1.1, the mean value of 0.63 is in close agreement with the 0.67 value suggested by theory and supported by R.G. Dean's 1977 analysis of oceanic beach profiles. Conversely, no correlation was found with B. Moore's 1982 curve relating the coefficient A to mean sediment size on the profile. Equilibrium profile adjustment to lake-level change was found to lag either a rise or fall in lake level. The lag period could not be determined, but appears to be on the order of years.