Cusps development after cyclone (Vardah) along the east coast of India: data and theories

Abstract

Cusp formation and related processes are well-studied all over the world, but research along the Indian coast is scanty and fragmentary. This paper provides a detailed description of the geomorphology, characteristics, and development of a series of cusps after the cyclone “Vardah” crossed along the east coast of India on 12^th December 2016. Observations of instantaneous shoreline, cusp dimension, and related processes such as wind, wave, littoral environmental observation (LEO), sediment texture, and total suspended sediment load in the surf zone were obtained for three discrete observations spanning 20 days, revealing a clear insight into the post cyclonic beach processes and the cusp development. The cusp development shows an accretionary environment (12 m in 20 days) and sediment characteristics show to coincide with cusp evolution as coarser sediment at horns than the bays. After the storms, the mean grain size decreases and the sorting value increases along the coast. The spacing of observed cusps ranged from 15 to 40 m with a dominant spacing of 20–30 m (80%) while cusp depths are mostly 4–6 m (55%) and range from 2 to 8 m. The cusps are formed under the influence of low wave energy, anticipated from numerical modeling study; wave height (H_s) is 0.6 m, wave period (T_s) is 6 s, and wave direction is 90 deg. The present study reveals that cusp formation along this region is a better fit with self-organization theory.