Simulasi Numerik Gelombang (Spectral Waves) Dan Bencana Rob Menggunakan Flexible Mesh Dan Data Elevation Model Di Perairan Kecamatan Sayung, Demak

Abstract

<p>Pesisir Kecamatan Sayung merupakan wilayah abrasi di Kabupaten Demak yang terkena dampak paling parah dari kenaikan muka air laut. Tujuan penelitian ini untuk mengetahui dinamika gelombang yang terjadi pada setiap kondisi pasang surut dan pengaruhnya terhadap rob serta <em>overtopping</em> yang terjadi. Metode penelitian adalah deskriptif kuantitatif menggunakan persamaan numerik, simulasi MIKE 21 dan model elevasi ArcGis. Hs tahun 2016 pada pasang purnama 0,015 – 0,359 m dan pada surut purnama 0,009 – 0,358 m. Hasil pengolahan data menunjukkan ada perbedaan yang drastis genangan yang terjadi pada saat pasang dan surut. Luas area model genangan rob pada tahun 2016 sebesar 7200,36 Ha. Untuk jarak terjauh genangan rob dari garis pantai pada tahun 2016 sejauh 10826,7 m. Terdapat peningkatan tinggi gelombang termasuk kondisi pasut purnama dan perbani tiap tahunnya. Hal ini menunjukkan abrasi terjadi di pengaruhi oleh kikisan gelombang yang terjadi secara terus-menerus. Kenaikan muka air laut yang terjadi setiap tahunnya berbanding terbalik dengan luas genangan yang dihasilkan, sehingga perlu dilakukan tindakan yang preventif pada proses tata kelola ruang pesisir. </p><p> </p><p><strong>Kata kunci</strong><em>:</em><em> </em><em>model elevasi, gelombang, model numerik, banjir rob, Sayung</em></p><p><em><br /></em></p><p class="ColorfulList-Accent11" align="center"><strong><em>NUMERICAL SIMULATION OF SPECTRAL WAVES AND ROB DISASTER USING FLEXIBLE MESH AND DATA ELEVATION MODEL IN WATERS OF SAYUNG DISTRICT, DEMAK</em></strong><strong><em></em></strong></p><pre><em>Coastline area in subdistrict Sayung is an abrasion area in Demak which has the worst affected of sea level rise. The purpose of this study to determine the wave dynamics that occur in any tidal conditions and their effects on tidal flood and overtopping happened. The research method is quantitative descriptive using numerical equations, MIKE 21 simulation and ArcGIS elevation models. Hs 2016 on a tide 0.015 to 0.359 m and in full retroactively from 0.009 to 0.358 m. The results of data processing showed no drastic difference puddle that occur at high tide and low tide. The area of tidal inundation model in 2016 amounted to 7200.36 Ha. To the farthest distance from the shoreline tidal inundation in 2016 with a distance of 10826.7 m. There are an increasing wave heights including a full moon and neap tide conditions each year. This shows abrasion occurs is influenced by the piling up of waves that occur continuously. Sea level rise that occurs annually is inversely proportional to the resulting inundation area, so we need a preventive action on the processes of governance of coastal areas.</em></pre><pre> </pre><pre><strong>Keywords</strong><em>: elevation models, waves, numerical models, tidal flood, Sayung</em></pre><p><em><br /></em></p>

Hydro-Oceanographic and Water Quality Assesments As a Basis for the Development of Offshore Aquaculture in the Weh Island, Aceh Province, Indonesia

“…Formzahl of 0.25 ≤ F <1.5 means to have a mixed tide prevailing semidiurnal tidal type. Sea level rise that occurs every year is inversely proportional to the area of inundation produced (Ondara et al, 2016) Current characteristics in Ie Meulee Current velocity measured at 5 different depths is divided into 5 cells, namely cell 1 at a depth of 3.5 m; cell 2 at a depth of 5.5 m; cell 3 at a depth of 7.5 m; cell 4 at a depth of 9.5 meters, cell 5 at a depth of 11 meters and cell 6 at a depth of 12.5 meters. Surface velocity (cell 1) ranges from 1.5-85.6 cm/s, the current velocity in the water column (cell 3) ranges between 0.4-75.4 cm/s, near-base current velocity (cell 5) ranges from 0.30 to 55 cm/s.…”

Total Suspended Solid (TSS) Distributed by Tidal Currents during Low to High Tide Phase in the Waters of Sayung, Demak: Its Relations to Water Quality Parameters

“…The ebb flow of waters still occur in the Sriwulan waters, with the dominant current direction moving away from the coast with speed ranged from 0.02 to 0.2 ms -1 , current that comes from the north moves along the coast and heading to the south with speed ranged from 0.02 to 0.06 ms -1 . The current pattern still in the condition of displacement from ebb to tide, the tide flow has begun to enter from the direction West northwest and perpendicular to the Timbulsloko waters, so that in the region of Timbulsloko waters occur the turbulence of bottom particles, which eventually suspended and floating in the water column (Ondara and Wisha, 2016). The results of hydrodynamic model only simulated on the condition ebb to tide, according to with the same time of sampling, but it can be different for other tidal conditions, error models MRSE obtained by 11,25%.…”

“…Total suspended solid (TSS) is the total number of solids that is suspended and floating in the water column, and the transport of TSS is strongly influenced by the mass transfer of water, and at some point, will settle back to the bottom of the water when it flows turbid weakened (Wisha and Heriati, 2016). In waters of Sayung have a tendency to flow pattern that varies according to the wind direction to be around the area, currents moving towards the coast produce currents along the coast a parameter stirring and milling in the coastal areas (Ondara and Wisha, 2016). The situation will affect to changes in the coastal region (Widada et al, 2012), changes in coastal is easier to detect using the status of water quality that is caused by the increased suspense sediment and other solid substances in waters (Wisha et al, 2015).…”

The Importance of Nutrients Concentration Monitoring In Coastal Area

“…Tidal current pattern still in the condition of displacement from ebb to flood, which has begun to enter the coast, from southeast to northwest and perpendicular to the estuaries of Pangandaran coast. It induces the turbulence on bottom particles due to the movement of longshore and rip currents,eventually suspended and floated in the water column (Ondara and Wisha, 2016). The particles are consisted of nutrient compounds and several organic-inorganic matters which are transported by the currents.…”