GEOSC 040 Lecture Notes - Lecture 24: Coastal Engineering, Beach Nourishment, Longshore Drift
Document Summary
Caused by oblique angle of wave approach. Waves refract during shoaling and change angle of approach. Bottom morphology determines pattern of refraction: waves turn to align with the bottom contours. Longshore drift can supply and remove sediment from the near shore region. Erosion of headlands salient: wave energy focused. Example: california coast: accumulation of sand in scalloped coastal embayments, more resistant points are exposed and attacked by waves. It"s a rip current not a rip tide . Strong offshore-directed current: typically in deeper rip channel. Rip currents 10s to 100s meters wide. Rip currents occur in rip channel: water is deeper in rip channels therefore the waves don"t break unyil very near shore. Methods of coastal engineering: groins, seawalls, replenishment. Beach nourishment: often thought as the best solution, costly, commonly dredged offshore, fine-grained, erodes too easily. Breakwater, seawall: protect beach but increase beach erosion in front and beside wall.
