An analytical model for the prediction of rip spacing in intermediate beaches

Considering the diversity of rip currents based on the classification of Castelle et al. (2016), it is crucial to study the characteristics of each individual rip current type, which are classified based on different dominant controlling forces and physical driving mechanisms. In this study, an analytical model was presented to predict the spacing of channel rip currents $$(S_{\mathrm{rip}})$$ in intermediate beaches using the equations of continuity and momentum. Then, the analytical model predictions were compared with the results of numerical simulations calibrated with field studies of other researchers, that showed good agreements. The main results of this study showed that rip spacing was simultaneously related to the characteristics of wave and bed in the surf zone. In addition, it was shown that due to inevitable changes of the hydrodynamic and morphological conditions of rip channel in the beach, the parameter $$H_{b0}/h_{c}$$ (where $$H_{b0}$$ is the wave height before approaching the sand bar and $$h_{c}$$ is channel depth) is an important factor in predicting the rip current situation and the changes of the beach state with time.