Rip Currents

Rip Current Embayments

A rip current embayment is an erosional "hot spot" feature expressed in the shoreline and formed by a rip current system. Rip embayments are crescent shaped features and have steeper slopes at the maximum point of erosion. The size, spacing, and location are dependant upon the magnitude of the rip current system. The rip current embayment itself is not necessarily a coastal hazard but rather it creates a weakness in the beach's natural defense system, which leaves the beach locally susceptible to high energy events. Relative to the adjacent section of beach, wave energy can propagate further towards the shoreline through the center of the embayment due to an increased nearshore water depth and reduced beach width. This wave energy can induce erosion and attack the coastal dunes, cliffs, bluffs, and coastal infrastructure. These features have been identified throughout the world and are a prominent feature along many sections of the Oregon coastline.

Observations of Rip Current Embayments along the Oregon Coastline

Recent research at Oregon State University has led to a methodology to measure rip current embayments from MLW shorelines derived from LIDAR data. This research focused on four sections of the Oregon Coastline; the Nehalem sub-cell, Rockaway sub-cell, Netarts sub-cell, and Siletz sub-cell. A total of 99 embayments were measured with an average length and amplitude of 575 and 17 meters (Dalon, 2007a; 2007b)

Continued research efforts will include:

  • Measuring the development of a rip current embayment through its life cycle.
  • Modeling the development of a rip current embayment (Computer/Physical)

U. Delaware Experiments

Data from the rip current experiments performed at the U. of Delaware can be found here. Further information about these experiments has been published in the following:

  • Haller, M.C., R.A. Dalrymple, and I.A. Svendsen, Experimental study of nearshore dynamics on a barred beach with rip channels, J. Geophys. Res., 107 (C6), 3061, doi:10.1029/2001JC000955, 2002.
  • Haller, M.C. and R.A. Dalrymple, Rip current instabilities, J. Fluid Mech., 433, 161-192, 2001.
  • Haller, M.C. and R.A. Dalrymple, Rip current dynamics and nearshore circulation, Center for Applied Coastal Research, Res. Rep. CACR-99-05, Center for Applied Coastal Research, University of Delaware, (also Ph.D. Thesis), 1999.
  • Chen, Q., Dalrymple, R.A., Kirby, J.T., Kennedy, A.B., and M.C. Haller, Boussinesq modeling of a rip current system, J. Geophys. Res., 104 (C9), 20,617-20,637, 1999."