Geomorphic response-type model for barrier coastlines: a regional perspective

Abstract

Based on quantitative documentation of historical changes in shoreline position between 1847 and 1991, eight geomorphic response-types were established for classifying megascale changes along barrier coastlines: (1) lateral movement, (2) advance, (3) dynamic equilibrium, (4) retreat, (5) in-place narrowing, (6) landward rollover, (7) breakup, and (8) rotational instability. Long-term (decades to centuries) monitoring of shoreline position over a spatial scale of 10 to 100 km provides a scientific basis for documenting process-response relationships that shape regional coastal morphodynamics. Although megascale shoreline change studies often are lacking, this type of information is critical for developing realistic research and management strategies regarding form/process relationships in coastal depositional systems. The spatial distribution of geomorphic response-types is delineated along the barrier coastlines of Louisiana, Mississippi, and southern Georgia/northern Florida. At megascale, the rate of relative sea level rise along these barrier coastlines appears to be one of the major factors controlling the occurrence of geomorphic response-types; however, sediment supply exerts significant influence on shoreline response as well.