Long-Term Variations in Nearshore Wave Climate and Littoral Drift at Ganpatipule Coast, Eastern Arabian Sea and its Link to Pacific Climate Variability

摘要

Nearshore wave characteristics and its variations at Ganpatipule coast, eastern Arabian Sea, for the past 4 decades (1979-2016) have been examined. The study is based on European Centre for Medium-Range Weather Forecasts Re-Analysis-Interim wave data at similar to 50 m water depth and the nearshore wave parameters estimated using the numerical model Simulating WAves Nearshore, executed from the Delft3D dashboard considering shallow water wave propagation, wave setup, and breaking. The littoral drift is estimated based on bulk transport formula of the Coastal Engineering Research Centre with the input from the hydrodynamic module. The model shows good agreement with wave rider buoy measured wave parameters at 14-m water depth. Anomalies of breaker height, period, and direction vary in the range of -0.35-0.4 m, -0.80-1 s, and - 16 to 12 degrees, respectively during the study period. A detailed analysis of monthly variations of breaker height along the study region suggests a significant increasing trend during the Asian summer monsoon, whereas a decreasing trend is identified during the nonmonsoon period. The study region accounts for a northerly net transport of 3.9 x 10(5) m(3) yr(-1) with a significant increasing trend of 1,840 m(3) yr(-1). The strong wind field region along the central Arabian Sea (65-70 degrees E and 15-20 degrees N) gives a strengthened positive correlation (r > 0.7) with the littoral drift. Impacts of Pacific climate variability on interannual and decadal timescales are observed in the littoral drift rates.