Model Transformasi Gelombang di Pelabuhan Patimban, Kabupaten Subang dengan Tiga Skenario

Pembangunan dermaga dan breakwater (pemecah gelombang) di Pelabuhan Patimban, Kabupaten Subang, Jawa Barat dapat mengakibatkan transformasi gelombang di perairan sekitarnya. Pemodelan transformasi gelombang penting untuk memberikan informasi sekaligus memprediksi seberapa besar pengaruh pembangunan dermaga dan breakwater terhadap perairan di sekitarnya. Tujuan dari penelitian adalah untuk mengetahui ada tidaknya transformasi gelombang dengan menggunakan tiga skenario. Penelitian lapangan dilaksanakan pada Januari sampai Februari 2020. Data yang digunakan adalah data gelombang hasil pengukuran lapangan, data angin, dan data batimetri. Peramalan gelombang dengan menggunakan metode Sverdrup-Munk Bretschneider (SMB). Pemodelan gelombang menggunakan model hidrodinamika untuk mengetahui besar transformasi gelombang. Tiga skenario yang digunakan yaitu skenario 1 (tanpa ada dermaga dan breakwater), skenario 2 (ada dermaga tanpa breakwater), dan skenario 3 (ada dermaga dan breakwater). Hasil simulasi menunjukan bahwa terjadi transformasi gelombang yang meliputi refraksi, refleksi, difraksi dan shoaling di Pelabuhan Patimban, dengan nilai koefisien refraksi tertinggi pada skenario 1. Penurunan tinggi gelombang terjadi pada skenario 2 dan skenario 3. The construction of a pier and breakwater at Patimban Port, Subang Regency, West Java can create wave transformation in the surrounding waters. Wave transformation modeling is important to provide information as well as predict how much influence the construction of the pier and breakwater will have effect on the surrounding waters. The purpose of this research is to determine the three scenarios effects for wave transformation. Field research was carried out from January to February 2020. The data used were wave data from field measurements, wind data, and bathymetry data. Wave forecasting using the Sverdrup-Munk Bretschneider (SMB) method. Wave modeling uses hydrodynamic models to determine the magnitude of the wave transformation. Three scenarios are used, namely scenario 1 (without a pier and breakwater), scenario 2 (there is a dock without a breakwater), and scenario 3 (there are a pier and breakwater). The simulation results show that there is a wave transformation which includes refraction, reflection, diffraction, and shoaling at Patimban Port, with the highest refraction coefficient value in scenario 1. A reduction in wave height occurs in scenarios 2 and scenario 3.

Hydrodynamics Features and Coastal Vulnerability of Sayung Sub-District, Demak, Central Java, Indonesia

The Sayung sub-district is an abrasion area in Demak Regency that is mostly affected by sea level rise. The purpose of this research is to determine the features of hydrodynamics and coastal dynamics occurrence in the sub-district of Sayung. Collecting field data/information and modeling approach (tides, waves, currents, weather and coastline changes) have been done in Sayung, Demak. The wave height in the eastern coast is the highest. The significant wave height in 2004 was greater than March 2016 showing that in 2004 the wind energy transfers were larger than 2016. The refraction coefficient in 2016 for all directions was the greatest from the west at the depth of 8 m and the smallest one was identified in the south. The refraction coefficient in 2004 for any direction yielded the largest value in the southwest at the depth of 2 m and the smallest one was identified the south as well. During a cycle of tidal fluctuation, it occurs twice flood and ebb events. The maximum depth is 6.5 m located about 3.8 km from the coastline. The sediment thickness reached 564,886.39 m3. Coastline changes occurred in 2003 and started to gain sedimentation in 2015. Data and information produced can be useful as a basis for further developments to mitigate abrasion and to create policy-brief in managing coastline affected abrasion even though some improvement efforts have been made.