Submerged breakwater effectiveness based on wave spectrum changes in Panjang Island, Jepara

Abstract

Jepara government took the initiative to construct submerged breakwaters to reduce wave force. Development planning of submerged breakwater need to analyze the reduction of wave spectrum (H and T) around the breakwaters. On this research we applied two variances of structure. Analysis of wave spectrum used 2D hydro-dynamic mathematical model. Data that has been used for input model there are bathymetry data, wind data along 2009-2019, tide data, and coastline data. Wave height and wave period data was obtained by wind data along 2009-2019 which was calculated using DNS method. Model simulation of wave height and period applied in two formation at 5 wind direction (North, Northeast, East, Southeast, and South). Effectiveness is known by the changes of Hmax and T while passing the structure. Based on simulation model, highest wave height found during southeast wind and reduced after passing the breakwaters. Breakwaters with 4 structure (formation 2) has higher reduction percentage. Incoming wave height values decrease after passing submerged breakwater.