Study of the Sedimentation Trend in the Prospective Area of Port of Marine Center, Cirebon Based on Remote Sensing Data

A coastal zone is the interface between the land and water that influenced by both of them. Coastal dynamic is influenced by many factors from land and sea, such as sedimentation and current. In order to support marine facility, Marine Geological Institute of Indonesia (MGI) plan to build a port. The prospective area is behind MGI office at Cirebon. This study use multi temporal remote sensing data in order to observe trend of coastline change around MGI. Based on the interpretation of the data, there are sedimentation around the MGI water and abrasion due to the presence of Kejawanan’s jetty and Kalijaga River. The result also shows that the current in this region is moving from southeast to northwest. The presence of the Kejawanan’s jetty stymies the movement of sediment. The sediment which is normally moving to the north of the jetty is then trapped on the south side of the structure, so that the sediment precipitates in this region and makes it as the active region of sedimentation and accretion. The presence mangrove conduces to support sedimentation speed and accretion at this region, because of his function as the catchment area. Abrasion occurs in the eastern part of MGI office at the Kalijaga river mouth within the bay. The Kalijaga River mouth is predicted to be the primary source of sedimentation in this area. The coastline change caused by sedimentation will be continuing as long as it is supplied by the sediment. The direction of the sedimentation is parallel to the jetty and it forms ellipsoid, with the sedimentation/accretion region is behind MGI office. The abrasion area is found in Kalijaga River mouth and a small area beside Kalijaga River. In order to build a port, we have to consider this sedimentation process. One of the alternatives to build the port is to make a quay pile model which gives way the current to pass through the other side of the port. Another alternative is to build the port as a pond model but it needs accuracy in building the mouth of jetty to minimize the sedimentation process. Keyword : sedimentation, Cirebon, remote sensing Pantai/pesisir merupakan wilayah antara daratan dan lautan yang masih dipengaruhi oleh keduanya. Dinamika pantai dipengaruhi oleh faktor-faktor dari daratan dan lautan seperti sedimentasi dan arus. Untuk menunjang “marine facility center†Puslitbang Geologi Kelautan (P3GL) bermaksud untuk membangun pelabuhan. Daerah yang prospektif adalah di belakang kantor P3GL, Cirebon. Studi ini menggunakan data citra satelit multi temporal, yang berguna untuk melihat arah perkembangan dan Perubahan garis pantai di belakang kantor P3GL dan sekitarnya. Berdasarkan interpretasi data citra, di daerah studi ditemukan adanya daerah akresi/sedimentasi dan daerah abrasi yang disebabkan oleh adanya dermaga Kejawanan dan adanya sungai Kalijaga. Hasil studi juga menunjukkan arah arus umumnya bergerak dari tenggara menuju barat laut. Keberadaan jetty Kejawanan menyebabkan aliran arus dan sedimen terhenti. Sedimen yang seharusnya bergerak ke arah utama menjadi terhalang dan terjebak di bagian selatan jetty, sehingga mengendap di daerah ini. Keadaan ini menyebabkan daerah ini menjadi daerah sedimentasi yang aktif (akresi). Keberadaan mangrove pada daerah ini juga menambah kecepatan sedimentasi di daerah ini, karena berfungsi sebagai daerah tangkapan sedimen. Abrasi terjadi di sebelah timur P3GL, tepatnya pada daerah lengkungan teluk dan di mulut sungai Kalijaga. Daerah mulut sungai Kalijaga diprediksi sebagai sumber sedimen pada daerah ini. Perubahan garis pantai yang disebabkan oleh sedimentasi akan terus berlangsung di daerah ini, selama adanya pasokan sedimen. Sedimentasi ini akan berlangsung sampai arahnya sejajar dengan jetty Kejawanan dan akan membentuk ellipsoid, dengan daerah sedimentasi berada di sekitar jetty dan belakang P3GL sementara daerah abrasi berada di sungai Kalijaga dan daerah sebelahnya. Karena itu, pembangunan pelabuhan P3GL sebaiknya memperhatikan kondisi ini. Salah satu alternatifnya adalah dengan membuat pelabuhan model tiang pancang yang memungkinkan arus dan sedimen untuk bergerak ke sisi sebelahnya. Alternatif lain adalah dalam bentuk kolam pelabuhan, tetapi harus tepat memperhatikan mulut pelabuhan untuk meminimalkan sedimentasi yang terjadi

Distribusi Karbon Organik dalam Sedimen Inti di Perairan Lembata, Laut Flores

Kondisi lingkungan dapat diketahui berdasarkan jejak karbon organik dalam sedimen inti. Penelitian bertujuan untuk mengetahui Perubahan lingkungan saat sedimen terendapkan. Lokasi penelitian berada di perairan utara Pulau Lembata, Laut Flores. Bahan yang digunakan adalah sampel sedimen inti yang diambil menggunakan penginti jatuh bebas pada 7 (tujuh) lokasi dengan sayatan oles. Karakteristik sedimen bagian timur didominasi fragmen biogenik dan sedimen lebih halus. Bagian tengah memiliki komposisi relatif sama antara fragmen batuan dengan biogenik. Bagian barat didominasi oleh fragmen biogenik. Persentase material organik antara 2.496-11.133%, CaCO3 (karbonat) 16.365-79.910% dan total organik karbon 0.999-4.453%. Distribusi karbon organik dalam sedimen inti menunjukkan Perubahan dinamis di wilayah perairan tengah dibandingkan dengan bagian barat dan timur. Perubahan distribusi karbon organik terjadi karena adanya perbedaan sumber asal sedimen, perbedaan morfologi dasar laut, Perubahan kekuatan dinamika perairan, pemanfaatan kesuburan perairan, dan perbedaan produktivitas perairan saat material karbon organik terendapkan. Kata kunci: sedimen, karbon organik, total organik karbon, perairan LembataEnvironmental conditions can be traced through recording the distribution of organic carbon content in core sediments. This study aims to determine environmental changes when sediment is deposited in Lembata waters. The research location is in the north waters of Lembata Island, Flores Sea. The materials used were core sediment samples taken using gravity core at seven locations. The study method uses a Loss On Ignition (LOI) procedure. The results of the analysis of the upper smear slide (0 cm). The eastern part is dominated by biogenic and sedimentary fragments which are finer than the western-central part, the middle part has a relatively similar composition between rock and biogenic fragments. in the dominant western part is a brightly colored material fragment. The change in the percentage of organic material is between 2,496-11,133%, the concentration of CaCO3 ranges from 16,365-79,910% and the concentration of TOC ranges from 0.999-4,453%. Distribution of organic carbon in core sediments from Lembata waters shows dynamic changes in the middle waters compared to the west or east. Changes in the distribution of organic carbon in Lembata waters occur due to differences in sources of sediment origin, differences in seabed morphology, changes in the strength of water dynamics, utilization of aquatic fertility, and differences in waters productivity when organic carbon material is deposited

Karakteristik dan Distribusi Lumpur Sidoarjo Sepanjang Sungai, Estuari dan Perairan Porong

Semburan lumpur Sidoarjo (Lusi) di daerah Porong menambah fungsi Sungai Porong menjadi sarana untuk mengalirkan lumpur ke arah laut, karena kemampuan tanggul – tanggul penghalang di sekitar lokasi semburan sangat terbatas. Kondisi ini berdampak pula terhadap terbawanya lumpur lapindo ke perairan Porong. Penelitian ini bermaksud untuk mengetahui sebaran sedimen di sungai, muara dan perairan sekitar Porong terutama yang bersumber dari luapan lumpur Sidoarjo. Materi yang digunakan dalam penelitian ini adalah sebanyak 30 sampel sedimen hasil sampling yang diambil di lokasi sungai – muara sungai Porong dan 30 sampel sedimen permukaan dasar laut di perairan sekitar muara sungai Porong. Distribusi umum sebaran sedimen di perairan Porong menunjukkan sedimen lumpur ditemukan di pinggir sungai dan sedimen pasir ditemukan di bagian tengah sungai. Distribusi umum sedimen dasar perairan di sekitar muara Porong berupa pasir, lempung dan lempung lanau pasiran. Hasil analisis mikroskopik dan SEM menunjukkan bahwa sedimen yang berasal dari luapan lumpur Sidoarjo ditemukan di sepanjang aliran Sungai Porong sampai muara, namun belum ditemukan di perairan luar sekitar muara Porong. Sedimen Lusi yang sampai ke muara Porong berukuran butir sampai 2,5 mikron. Deskripsi megaskopis menunjukkan sedimen Lusi pasir - kerikil umumnya berbentuk pipih (halus– agak halus). Hasil SEM menunjukkan bahwa sedimen yang berasal dari lumpur Sidoarjo umumnya seragam dan didominasi berupa smectite. Berbeda dengan sedimen sungai, hasil SEM yang diperoleh dari sampel laut yang menunjukkan sedimennya beragam, berupa montmorilonite, kaolinite dan illite. Kata Kunci : Sedimen, Porong, lumpur Sidoarjo The Sidoarjo mudflow in the Porong area increases the functions of Porong River as media to drain the muds towards the sea, because the ability of embankments in the area as a barrier is very limited. This condition intends to determine the presence and distribution of sediment in rivers, estuaries and waters originating from the Lusi mudflow. The materials used in this study are the sediment sampling results as many as 30 samples taken from the river and off the river mouth and 30 samples of sea surface sediments in the surrounding waters. General distribution of sediments in the Porong River shows the form of mud sediments are generally found in the riverside and sandy sediment found in the middle of the river, while the distribution of sediments in waters Porong form of sand, clay and sandy silt clay. The results of microscopic and SEM analysis showed that the sediments derived from the Lusi mudflow found along Porong River till estuaries, but they have not reach surrounding water of Porong estuary. The Lusi sediment that reached the estuary Porong sized to 2.5 micron. General megascopic description show the shape of the Lusi sediment as sand-gravel is a flat-shaped (rounded - sub rounded). SEM results showed that the sediments derived from the Lusi is generally uniform and dominated by smectite. In contrast to stream sediments, the SEM results obtained from marine sediment samples show a variety of sediments, in the form of montmorillonite, caolinite and illite. Key words: Sediment, Porong, Sidoarjo, Mud Overflow (Lusi

Kajian Dinamika Pantai Selatan Banyuwangi Berdasarkan Hasil Penafsiran Citra Satelit Landsat Tm

Hasil kajian citra satelit Landsat Thematic Mapper (TM) menunjukkan daerah pantai selatan Banyuwangi mempunyai empat karakteristik dinamika pantai, yaitu daerah akresi, terjadi di muara Sungai Gonggo, Sungai Baru, dan Sungai Pergaul yang terjadi karena tingginya aliran (run off) dari sungai. Daerah abrasi terjadi di Teluk Grajagan yang terjadi karena adanya arus menerus dari laut sehingga sedimen dari Segoro Anakan tidak bisa diendapkan di daerah teluk dan hanya di muka sungai. Daerah abrasi dan akresi terdapat di teluk Rajegwesi dan Pancamaya yang mempunyai daerah akresi di muara sungai dan daerah abrasi di bagian sisi teluknya. Daerah stabil, terdapat di daerah-daerah yang menjorok ke laut dan sepanjang pantai Alas Purwo. Daerah akresi maupun abrasi umumnya terjadi di daerah topografi rendah, landai dan berupa aluvium, sedangkan daerah stabil terdapat pada daerah dengan topografi bertebing dan batuan penyusun berupa batuan keras. Kata kunci : sedimen, dinamika pantai, Landsat TM, pantai selatan Banyuwangi The result of the assesment of Landsat TM imageries show that the coastal area of south Banyuwangi have four coastal dynamic characteristics those are: accretion, abrasion, accretion and abrasion, and stable areas. Accretion area, is located in the river estuary of Gonggo, Baru, and Pergaul rivers that occur by run off from river. Abrasion area, is located in Grajagan Bay caused by continuous current from the sea so that the sediment from Segoro Anakan cannot precipitate in the bay area but only in the river mouth. Abrasion and accretion areas are located in Rajegwesi and Pancamaya Bays where the accretion area is in a river estuary but the abrasion area is in the side shares of the bay. Stable area is located in the peninsula area and along the Alas Purwo coast. Generally the accretion or abrasion areas were occurred in low relief topography and occupied by alluvium, whereas the stable area is characterized by the high relief topography consisting of hard rock. Key words: sediment, coastal dynamic, Landsat TM, south coast of Banyuwangi

Characteristic of Shallow Subsurface Quaternary Sediment in Nongsa Isle, Part of Putri Islands, Batam, Based on Georadar Data Interpretation

Nongsa Isle belongs to Putri Islands in Batam, is the outermost island that need to be protected either from natural hazards and anthropogenic factor. Therefore, this study was conducted by performing Ground Penetrating Radar analysis, in order to understand the geological condition particularly sedimentology and its process. We used Sirveyor 20 GPR equipment type with MLF antenna frequency 40 Mhz and Radan 5 as processing software, which include time zero correction, spatial filter, deconvolution, migration and adjustment of amplitude and signal gain. Data interpretation was conducted based on radar facies methodology that describes georadar image/radargram. The study result showed differences of sedimentary facies based on three differences of radar facies units, with the first layer (unit 1) is the youngest unit has thicknesses ranging from 3.5 – 5 m that characterized by parallel, strong reflector, high amplitude and continuous reflector configurations, unit 2 from 5 – 11 meter of depth, indicates parallel reflector pattern with medium-high amplitude and continuous, and unit 3 which is the oldest unit with thickness until penetration limit (11 – 20 m), characterized by a configuration of sub parallel – hummocky reflectors that are undulating, low-medium amplitude reflectors. Based on radar facies characteristics such as reflector configuration, reflection amplitude, and reflection continuity, the differencies of depositional facies are changes from fluvial – coastal plain