Tsunami induced scour at onshore coastal structures can cause exposure of the foundations
and lead to failure. This paper presents experimental observations of a 147 s crest-led wave
inundation, causing scouring and loading on 0.2 m wide square and 0.4 m wide rectangular onshore
structures. At 1:50 Froude scale these equate to a 17.3 min inundation at 10 and 20 m wide structures.
Scour development is measured using GoPro cameras situated inside the Perspex structures. The
hydrostatic load is calculated from the integration of pressure readings along the front face of the
structures, and the hydrodynamic loading is estimated from the approach flow velocity, as measured
by a Vectrino II profiler. The results show that the maximum scour depth occurs during the inundation
before significant slumping decreases the end scour depth. Both the in-test and final scour depths for
the 0.4 m structure are greater, due to the larger blockage causing greater acceleration of the flow
around the structure. For both structures, the hydrostatic loading is dominant over hydrodynamic load
