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ANALISIS PERUBAHAN LUAS LAHAN MANGROVE DI KABUPATEN POHUWATO PROPINSI GORONTALO DENGAN MENGGUNAKAN CITRA LANDSAT Opa, Esry T
JURNAL PERIKANAN DAN KELAUTAN TROPIS Vol 6, No 2 (2010)
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (657.386 KB) | DOI: 10.35800/jpkt.6.2.2010.165

Abstract

A study on spatial evaluation of mangrove resource was carried out in Pohuwato Regency, the province of Gorontalo, for 3 months. The mangrove resources in this area have been exploited to build ponds, houses and for firewood. As the result, there was a significant decrease in mangrove population. In this study, main data were gathered from Landsat TM Satellite Image 2000-2001 and 2009-2010, and others data collected from the field and interviews with local villagers. Aproximately 60 sampling points were observed and examined. Normalized Difference Vegetation Index (NDVI) was applied to determine the extent of mangroves and its changes. In 2000-2001, the mangrove area was about 7,007.67 Ha, and reduced to 3,034.53 Ha in 2009-2010.
PERUBAHAN GARIS PANTAI DESA BENTENAN KECAMATAN PUSOMAEN, MINAHASA TENGGARA Opa, Esry T
JURNAL PERIKANAN DAN KELAUTAN TROPIS Vol 7, No 3 (2011)
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (777.465 KB) | DOI: 10.35800/jpkt.7.3.2011.187

Abstract

ABSTRACTBentenan village, located on the East coast of Minahasa peninsula and surrounded by gently sloping hills, has a shoreline of 1.3 km. The shape of the shoreline is curved facing Bentenan Island. It is observed that coastline had been gradually retreating. Research and data collection on the coastline has been conducted in November 2008. As many as 85 points have been plotted using GPS, rectified with LPI maps and compared with a couple of old maps, i.e., Peta Dishidros Lembar 334 1992 and Peta Laut No. 62 1985. Shoreline of Bentenan village shown to be retreated 165 meters in average towards the mainland from 1985 to 2008 (23 years), averaging a decrease of 7.17 meters. This indicates that the shore of Bentenan undergoes a process of erosion/ abrasion which causes changes in shoreline backwards towards the land, also called beach retreat.Keywords: Bentenan, shorelines, Abrasion, beach retreat, geomorphology.ABSTRAKDesa Bentenan memiliki panjang garis pantai sekitar 1,3 km, terletak di pantai Timur semenanjung Minahasa yang bertopografi landai dan dikelilingi oleh perbukitan. Bentuk pantainya melekuk ke dalam dan di bagian depannya terdapat pulau Bentenan. Teramati bahwa bentuk pantai ini makin mundur dari tahun ke tahun. Observasi dan pengukuran dilakukan pada bulan November 2008, sebanyak 85 titik telah dipetakan dengan menggunakan GPS dengan koreksi dari peta LPI dan hasilnya dibandingkan dengan beberapa peta terdahulu yaitu Peta Dishidros lembar 334 tahun 1992, Peta Laut No 62 tahun 1985. Perbandingannya menunjukan garis pantai desa Bentenan mengalami perubahan rata-rata sebesar 165 m mundur ke arah daratan dalam selang waktu 1985-2008 (23 tahun). Dalam periode tersebut setiap tahun daerah ini meng-alami kemunduran garis pantai rata-rata 7,17 m.Kata kunci: Bentenan, Garis pantai, Abrasi, Pantai mundur, geomorfologi.
Sediment Granulometry of the Beach at the Kalasey’s Groynes Simboh, Reyvalentin; Rampengan, Royke M; Manengkey, Hermanto W.K.; Djamaluddin, Rignolda; Opa, Esry T; Sinyal, Hengky J
Jurnal Ilmiah Platax Vol. 9 No. 2 (2021): ISSUE JULY-DECEMBER 2021
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35800/jip.9.2.2021.34778

Abstract

Coastal areas have the potential to be developed and utilized for various purposes. However, the intensity of coastal use can result in the degradation of the coastal environment. Therefore, management of the coastal areas is often carried out by building shore protective structures, including groynes. The placement of a structure in the form of a groynes is primarily intended to block littoral flow in moving sediment out of certain places in the shore. Therefore, the placement of groynes on the shore needs to be followed by a study to find out the effectiveness of the groynes. The effectiveness of groynes can be determined, among others, by a study on the granulometry of sediments on the beach. This study was conducted to describe the composition of the sediment and to analyze granulometry distribution in several places at the beach around the groynes on the shore of Kalasey. The study of the physical sediments around the Kalasey groynes was carried out through a study of the sediment samples from October 30, 2020, to April 27, 2021. Sediment sampling was carried out at 6 stations which have been determined on the surface of the beach formed around the groynes. The results obtained through this research showed that the composition of the sediments in the beach around the Kalasey groynes consisted of size classes as follows: very fine sand, fine sand, medium sand, coarse sand, very coarse sand, granule, and pebble. Fine-sized materials at the beach which is located in the groynes on further east have increased in composition. Based on the granulometric analysis of the sediment, it is indicated that the erosion and deposition processes occur alternately in the beaches formed around the groynes.Keywords: Beach; Kalasey Groynes; Sediment Composition; Granulometric AnalysisAbstrakWilayah pantai memiliki potensi untuk dikembangkan dan dimanfaatkan untuk berbagai kepentingan.  Walaupun demikian, intensivitas pemanfaatan pantai dapat mengakibatkan terjadinya degradasi lingkungan pantai.  Oleh karena itu, dalam rangka pengelolaan pantai seringkali dilakukan dengan cara membangun struktur pelindung pantai, diantaranya berupa groin. Penempatan struktur berupa groin di kawasan pantai, dimaksudkan utamanya untuk menghadang aliran litoral dalam memindahkan sedimen keluar dari tempat tertentu di kawasan pantai.  Oleh karena itu, penempatan groin di pantai perlu diikuti dengan kajian untuk melihat efektivitas fungsi groin pada kawasan pantai tersebut.  Salah satu cara untuk melihat efektivitas kerja groin di pantai adalah melalui kajian menyangkut granulometri sedimen gisik yang terhampar di sekitar groin yang ditempatkan. Penelitian ini dilakukan dengan tujuan mendeskripsikan komposisi sedimen dan menganalisis distribusi granulometri di beberapa tempat pada gisik sekitar groin di pantai Kalasey.  Kajian terhadap sedimen gisik sekitar groin Kalasey dilakukan melalui telaah terhadap sampel sedimen yang dicuplik mulai 30 Oktober 2020 sampai dengan 27 April 2021.  Pencuplikan sedimen dilaksanakan di 6 stasiun yang ditetapkan pada permukaan gisik yang terbentuk di sekitar groin Kalasey. Hasil yang diperoleh melalui penelitian ini adalah komposisi sedimen pada gisik di sekitar groin Kalasey terdiri dari kelas ukuran berupa pasir sangat halus, pasir halus, pasir sedang, pasir kasar, pasir sangat kasar, granul, dan kerakal.  Gisik yang terletak pada kawasan groin semakin ke arah Timur pada kawasan ini, komposisi sedimennya mengalami peningkatan jumlah material sedimen yang berukuran halus.  Berdasarkan analisis granulometri sedimen terindikasi bahwa proses erosi dan deposisi terjadi secara bergantian pada gisik-gisik yang terbentuk di sekitar groin.Kata kunci: Gisik; Groin Kalasey; Komposisi Sedimen; Analisis Granulometri