Laboratory experiments of tidal effect on beach processes

Abstract

Morphological beach changes in a macro-tidal environment are here considered in association with quantities of beach hydrodynamics such as nearshore wave transformation, water levels, and wave run-up through laboratory experiments. Laboratory experiments were conducted in two-dimensional glass-walled wave flume (45m long, 0.7m wide and 1.5m deep) at Kwandong University, Korea. Piston type wave generator can make regular and irregular waves with active absorption. Four capacitance wave gages and five ultrasonic wave gages were installed to collect water surface elevation at different cross-shore location. An electromagnetic current meter was mounted on the flat bottom section to collect horizontal water particle velocity from the offshore boundary. Two video cameras were deployed to monitor water surface in the inter-tidal zone both from a side wall of the wave flume. A movable beach was installed using fine sand (d50 = 0.012 mm) in the flume starting with 1/50 slope and ending with 1/20 slope.Irregular waves based on the Bretschneider&#8211 Mitsuyasu spectrum were generated with 2.3 cm of target significant wave height and 1.7 seconds of target significant wave period for one hour at each case. In order to consider waves and tide simultaneously, we changed water level gradually by using drain and pump during the wave generation. The bathymetry change was monitored by using video cameras not only before and aftertory experiments were conducted in two-dimensional glass-walled wave flume (45m long, 0.7m wide and 1.5m deep) at Kwandong University, Korea. Piston type wave generator can make regular and irregular waves with active absorption. Four capacitance wave gages and five ultrasonic wave gages were installed to collect water surface elevation at different cross-shore location. An electromagnetic current meter was mounted on the flat bottom section to collect horizontal water particle velocity from the offshore boundary. Two video cameras were deployed to monitor water surface in the inter-tidal zone both from a side wall of the wave flume. A movable beach was installed using fine sand (d50 = 0.012 mm) in the flume starting with 1/50 slope and ending with 1/20 slope.Irregular waves based on the Bretschneider&#8211 Mitsuyasu spectrum were generated with 2.3 cm of target significant wave height and 1.7 seconds of target significant wave period for one hour at each case. In order to consider waves and tide simultaneously, we changed water level gradually by using drain and pump during the wave generation. The bathymetry change was monitored by using video cameras not only before and after