Estimation of seasonal morpho-sedimentary changes at headland bound and exposed beaches along south Maharashtra, west coast of India

Knowledge on seasonal variation of morpho-sedimentary processes of tropical beaches is essential to evaluate inter annual variations to devising best protection strategy for the coastal zone. A study was taken up to understand the seasonal changes of physical processes at the headland bound and compared with exposed beaches. The spatio-temporal morpho-sedimentary dynamics were carried out through beach profiles, sediment samples, and simulated wave climates across two complete annual cycle. The beach profile survey was carried out using RTK-GPS, wherein the GRADISTAT was used for analysing sediment samples. The seasonal wave climates were studied with the SWAN model coupled with WAVEWATCH III. Observation shows, the sediment environment at headland bound beach is strongly dominated by fine sand throughout the year, whereas the exposed beach is illustrated from fine to medium sand across seasonal scale. The seasonal change in beach morphology occurs considerably in the exposed beach than that compared to headland bound. Successively, the occurrence of shoreline retreat is shown maximum up to 20 m in at the exposed beach during the monsoon. Both the locations showed strong seasonal variation in the wave energy as well as direction, whereas the nearshore wave energy at exposed beach is comparatively high with an average of 8342 J/m² than the headland bound due to less deviation in the wave propagation. The analysis of seasonal wave pattern together with beach morpho-sedimentary processes exhibit the influence of wave conditions at the exposed beach when compared with headland bound beach and so the study implies for offset morphological changes and tailored management to protect the beaches from natural coastal hazards.