Erosional signatures and reorganization in ridge-and-swale sequences

Tsunami and other extreme-wave deposits are often searched for along sandy, wave-dominated coastlines that are characterized by ridge-and-swale topography. Understanding the morphodynamics of beach-ridge formation and the evolution of ridge-and-swale topographies on short and long timescales is essential to identify sites where tsunami and storm deposits are most likely preserved. In addition, the geomorphic expression of individual ridges and beach-ridge sets provides an important proxy for overwash events, related modifications to sediment supply, and seismically induced land-level changes. Using a combination of remote-sensing techniques, field surveys, and sediment analysis, large-scale impacts on coastal morphologies can be detected and chronologies of extreme-wave events developed. This chapter introduces the characteristics of beach-ridge plains, summarizes the signature of tsunami- and storm-induced erosion and reorganization of such coastal settings, and describes approaches on how to best detect these imprints.