Spatial distribution of waves and wave-induced littoral drift along the nearshore regions of the central west coast of India

Abstract

The spatial distribution of nearshore wave characteristics and wave-induced littoral drift along the Central West Coast of India (CWCI) is investigated using a wave transformation model. Previous approaches in littoral drift estimations along the CWCI were based on single-point data, and the spatial distributions of littoral drift patterns along the CWCI were not attempted. A new approach has been implemented, where time and space varying measured wave data is used as an input to the model, collected at ∼15 m water depth at three locations in the CWCI. The model results are compared and validated with the measured wave data at 9 and 5 m during the monsoon and non-monsoon periods. On an annual scale, along the CWCI, the significant wave height varies from 0.8 to 1.2 m, the period in the range of 4–6 s, and the predominant direction is southwest-west (∼230–270°°). The study also examines alongshore varying energy fluxes in the CWCI. In the breaker zone along CWCI, wave height varies up to 18% during non-monsoon, while the period and direction vary less than 10%, and during monsoon, these variations are less than 7%. The present study also examines the spatial distribution of littoral drift along four selected stretches. A predominant southerly net drift is observed among most regions of CWCI. We also estimated the littoral drift during calm, monsoon, and cyclone conditions. It is observed that cyclone events that lasted for a few days generated ∼40% of the LST generated during an entire pre-monsoon season.