Effectiveness of Small Onshore Seawall in Reducing Forces Induced by Tsunami Bore: Large Scale Experimental Study

Tsunami force and pressure distributions on a rigid wall fronted by a small seawall were determined experimentally in a large-scale wave flume. Six different seawall heights were examined, two of which were exposed to a range of solitary wave heights. The same experiment was done without a seawall for comparison. The measured wave profile contained incident offshore, incident broken, reflected broken, and transmitted wave heights measured using wire resistance and ultrasonic wave gauges. Small individual seawalls increased reflection of the incoming broken bore front and reduced force on the rigid landward wall. These findings agree well with published field reconnaissance on small seawalls in Thailand that showed a correlation between seawalls and reduced damage on landward structures.