Morphometric and sediment characterization of beach cusps in connection to rip curren ts along Indonesia’s Parangtritis coast

The beach cusps in the Parangtritis coastal area are notable for their great propensity for rip current formation, which is hazardous to visitors and beach activities. This study aimed to identify the geographical distribution of beach cusps in the Parangtritis coastal area and the morphometric characteristics and sedimentary grain size in the same area. A combination of visual interpretation of the very highresolution aerial image and Beld measurements was utilized in this work to identify the geographical distribution and morphometry of beach cusps. A sedimentary grain size laboratory test with sieves is used in sediment analysis. We used Gradistat 9.1 to analyze the grain size characteristics, i.e., mean, sorting, kurtosis, and skewness. According to the Bndings of this study, beach cusps have a geographical distribution that spans the Parangtritis coastal area. The types of beach cusps in the study area can be categorized as crescentic bay, mega, and swash cusps. Beach cusp morphometric characteristics show size heterogeneity in each parameter. The cusp spacing values derived from the measurements vary from 10.68 to 558.14 m, the value range for cusp elevation is –0.56 to 10.57 m, the cusp depth ranges from 8.8 to 35 m, and the cusp amplitude ranges from 0.2 to 12 m. Furthermore, sand in the beach cusps’ horn portion is coarser compared with sand in the embayment area. Regarding beach cusps, there is currently a lack of documented databases along the Indonesian coastal area. Investigating the formation of beach cusps and characterizing the sediment involved can provide valuable insights for the purpose of e Dcient
coastal management.