Prediction of shore retreat and nearshore profile adjustments to rising water levels on the Great Lakes / by Edward B. Hands.

Abstract

PREFACEThis report provides coastal engineers with documentation that a wide zone of nearshore bathymetry responds to long-terra increases in water level by migrating inland with the receding shoreline.The dimensions of the zone affected depend on the wave exposure.A simple procedure is presented for estimating the magnitude of shore recession and the depth of profile adjustment for any sandy stretch of shore on the U.S. side of the Great Lakes.This report is based on a 9-year series of nearshore surveys conducted on the eastern shore of Lake Michigan.

Sea-level rise and shoreline retreat: time to abandon the Bruun Rule

“…Lastly, the SCOR report (1991) discussed how Hands (1979Hands ( , 1980Hands ( , 1983 compared erosion rates predicted by the Bruun Rule to measured rates, and found that although the Bruun Rule over-predicted shoreline retreat while the lake level was rising, the retreat rates showed good agreement after lake levels began to fall. Hands concluded that this delay in agreement was due to the time lag of profile response.…”

“…The global rise of sea level during the Holocene (Pirazolli, 1991) and during the historical period have prompted studies of the short-term response of shorelines to changes in water level (Hands, 1979(Hands, , 1980(Hands, , 1983Brambati et al, 1998;Ciavola and Corbau, 2002), geomorphological analysis of shoreline behaviour during transgression (Rosen, 1978;Carter and Orford, 1993;List et al, 1994List et al, , 1997 and investigations of transgressive coastal stratigraphic sequences (Kraft, 1978;Thom, 1983;Cowell et al, 1995;Cattaneo and Steel, 2003). Factors that cause changes in the morphology of coasts are numerous and include sediment supply, variations in wave energy, tidal currents, wind action, sediment type, tidal inlet dynamics, morphological feedback, etc.…”

The modified Bruun Rule extended for landward transport

“…Below we provide a brief review of the field studies that have been conducted of the Bruun Rule to determine its validity. Hands (1979Hands ( , 1980Hands ( , 1983 reported on observations of water level and associated shoreline changes on Lake Michigan from 1967 through 1976 during which the water level rose slightly more than 1 m and then fell by approximately 0.2 m. Of the six surveys conducted, four documented rising water level and two falling water level. It was found that the general characteristics of the shoreline response were consistent with the Bruun Rule and that the calculated recession lagged the measured recession.…”

Wave Energy Estimates and Bluff Recession Along Lake Michigan's Southeast Shore∗

“…Buckler (1973Buckler ( , 1981, Buckler and Winters (1983), and Powers (1958), for example, have inventoried and described subaerial physical attributes such as bluff height, orientation and composition, groundwater seepage, mass wasting, vegetative cover, and beach width, in an attempt to assess the importance of shorezone geomorphology in bluff recession. Others studied the subaqueous nearshore environment and sediment balance (Davis 1976;Gilbert 1986;Hands 1976Hands , 1980Hands , 1981Hands , 1984US Army Corps of Engineers 1984, 1986a, 198613, 1986c, 1986d. Several investigations conducted during a period of high lake level in the early to middle 1970s incorporated engineering approaches that evaluated relationships between several factors believed to influence erosion (Birkemeier 1981;Brater n.d.;Brater and Seibel 1973;Brater et al 1975;Davis 1976;Davis et al 1975).…”

“…Many authors (Birkemeier 1981;Brater and Seibell973;Buckler 1981;Buckler and Winters 1983;Davis 1976;Davis et al 1975;Gilbert 1986;Hands 1976Hands , 1980Powers 1958) considered the combined effects of both wave and storm characteristics on the Great Lakes shorezone. Liu (1970) and Liu and Housley (1970) presented some qualitative characteristics of waves from visual observations to better understand their nature and distribution.…”