Flow Characteristics of Runup Wave - Induced Seepage in Swash Zone

Abstract

The effect on beach unstabilization due to the runup wave-induced coastal seepage is investigated through the experiment and the numerical modelling. The groundwater flow is estimated by using the orbit of fluorescent paint injected into sandy beach model. As the result, the steep slope of phreatic surface is made the seaward and upward directed groundwater flow to accelerate. The numerical modelling simulates the interacting runup wave motion and groundwater flow. The exfiltration flux on backwash shows that beach face leads to unstable condition caused by the uplift seepage force. This seepage force is made to increase the unstable region while the phreatic surface is rising.