GEOMORPHIC RESPONSE-TYPE MODEL FOR BARRIER COASTLINES - A REGIONAL PERSPECTIVE

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) retr eat, (5) in-place narrowing, (6) landward rollover, (7) breakup, and ( 8) relational 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 ch ange studies often are lacking, this type of information is critical f or developing realistic research and management strategies regarding f orm/process relationships in coastal depositional systems. The spatial distribution of geomorphic response-types is delineated along the bar rier coastlines of Louisiana, Mississippi, and southern Georgia/northe rn Florida. At megascale, the rate of relative sea level rise along th ese barrier coastlines appears to be one of the major factors controll ing the occurrence of geomorphic response-types; however, sediment sup ply exerts significant influence on shoreline response as well.