Morphometric and sediment analysis of beach cusp in correlation to rip currents: a case study from tropical coast, West coast of India

Abstract

The presence of rhythmic beach cusps in foreshore regions are of persistent research interest to coastal researchers, engineers with respect to their formation in beaches. Morphometric and sediment analysis were used to study beach cusp morphology at Vengurla beach, a gentle slope beach characterized by medium sand. The cusp dimensions such as spacing, elevation, amplitude and depth were measured for detailed analysis. The distinctive sediment characteristics between the horn and the bays of the cusp are different and cusp measurements show a high level of irregularity. Horns and bays have medium sand, but sorting is varying. Sorting variations clearly demonstrated the difference in energy condition between horns and bay. Negative skewness of few horn samples has been correlated with erosional trend. Based on the grain size analysis result, it was observed that Vengurla beach cusps follow the regular grain size distribution pattern. Additionally, the low-intensity rip currents were also noticed in the study area. The rate of occurrence and strength of rip currents are decided by the nearshore bathymetry and play an imperative role in rip current formation. The present study is based upon the field measurements along Vengurla coast and contributes to morphometric analysis of beach cusps. Regarding beach cusps, there are no documented databases along the Indian coast. Understanding the beach cusp formation and its seasonal changes along the beaches will be useful for effective coastal management.