Purnomo Raharjo
Marine Geological Institute of Indonesia, Jl. DR. Junjunan No. 236, Telp. 022 603 2020, 603 2201, Faksimile 022 601 7887, Bandung

Published : 2 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 2 Documents
Search

THE RATE OF SEDIMENTATION ESTIMATION OF TANJUNG API-API ESTUARY SOUTH SUMATERA BY USING 210Pb PROFILE Purnomo Raharjo
BULLETIN OF THE MARINE GEOLOGY Vol 25, No 1 (2010)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (559.021 KB) | DOI: 10.32693/bomg.25.1.2010.23

Abstract

Sedimentary processes occur intensively in Tanjung Api-Api area situated in the estuary of Musi Banyuasin river. A study on 210Pb isotopes of the sediments has been done to understand the rate of sedimentation. For that purpose, the Marine Geological Institute of Indonesia (MGI) has also conducted bathymetry and sediment distribution mappings. Two samples represent depths of 17-30 cm and 190-210 cm below sea floor give age of 11.54 and 22.45 years. The average of sedimentation rate is 2.03 cm/years (from 0 to 0.3 m below seafloor) and 8.9 cm/years (until 2.1 m depth below seafloor). The result shows, decreasing sedimentation rate upward, that indicates the surficial sediment less influenced by wave and surface current nowadays. Keywords : 210Pb isotope, rate sedimentation, Tanjung Api-Api Proses sedimentasi yang intensif terjadi di kawasan Tanjung Api-Api yang terletak di muara Sungai Banyuasin. Penelitian isotop sedimen 210Pb untuk mengetahui kecepatan sedimentasi telah dilakukan oleh Puslitbang Geologi Kelautan, selain itu dilakukan pula pemetaan batimetri dan sebaran sedimen permukaan dasar laut. Dua buah contoh sedimen mewakili kedalaman 17-30 cm dan 190-210 cm di bawah dasar laut memeperlihatkan umur 11,54 dan 22,45 tahun. Kecepatan sedimentasi rata-rata 2,03 cm/tahun (pada kedalaman 0-0,3 meter di bawah permukaan dasar laut) dan 8,9 cm/tahun (hingga kedalaman 2,1 meter di bawah dasar laut). Hasil tersebut menunjukkan penurunan kecepatan sedimentasi ke arah atas, yang mengindikasikan bahwa pada saat ini gelombang dan arus kurang berpengaruh terhadap proses sedimentasi. Kata kunci : isotop 210Pb, kecepatan sedimentasi, Tanjung Api-Api
POTENTIAL HAZARDS OF SEDIMENT IN KENDARI BAY, SOUTHEAST SULAWESI Nur Adi Kristanto; Yogi Noviadi; Purnomo Raharjo
BULLETIN OF THE MARINE GEOLOGY Vol 23, No 1 (2008)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (901.029 KB) | DOI: 10.32693/bomg.23.1.2008.8

Abstract

Kendari bay is located in front of Kendari city. There are two harbors in the inner part of bay which very important to support economic activities such as shipping and passenger transportation. The result of coastal characteristic mapping and physical oceanography survey show various coastal morphology, vegetation, weathering processes, sedimentation, currents, and water depth and sea floor morphology. Kendari bay is an enclosed bay; the area is wide in the inner part and narrow in mouth of bay (outlet), the morphology look like a bottle’s neck. Numerous mouth rivers are concentrate around the bay. The rivers load material from land since erosion on land is intensive enough. There is indication that sediment supplies from land trough river mouth not equivalent with outlet capacity. Sediment load is trapped in the inner bay caused the outlet morphology. So high sediment rate play an important role in the process of shallow of water depth in Kendari bay. This condition make the Kendari bay is a prone area of sediment hazard due to height rate of sedimentary process. Therefore, to anticipate the hazards, precaution should be taken related to the Kendari bay as the center of activities in southeast of Sulawesi. The further survey is needed such as marine geotechnique and on land environmental to collect data, which can be used as database for development planning. Key words: Potential hazard, sediment, Kendari Bay Teluk Kendari terletak di bagian depan kota Kendari. Di bagian dalam teluk terdapat 2 pelabuhan yang sangat penting untuk menunjang kegiatan ekonomi seperti perikanan dan transportasi. Hasil pemetaan karakteristik pantai dan penyelidikan oseanografi memperlihatkan kondisi morfologi pantai, vegetasi, proses pelapukan, sedimentasi, arus, kedalaman air laut dan morfologi dasar laut. Teluk Kendari merupakan teluk tertutup yang lebar di bagian dalamnya dan sempit di bagian mulutnya dimana morfologinya terlihat seperti lehar botol. Beberapa mulut sungai terkosentrasi di sekitar teluk. Sungai bermuatan material dari daratan selama erosi didaratan cukup intensif. Hal ini mencerminkan indikasi suplai sedimen dari darat melalui muara sungai tidak sama dengan kapasitas pengeluaran. Muatan sedimen terperangkap di bagian dalam teluk dan menyebabkan terbentuknya morfologi cerobong. Tingginya muatan sedimen merupakan proses yang penting terjadinya pendangkalan di Teluk Kendari Kondisi tersebut menyebabkan Teluk Kendari cenderung merupakan daerah yang akan mengalami bahaya pendangkalan akibat tingginya proses sedimentasi. Oleh karena itu untuk menanggulagi bahaya tersebut, harus dilakukan pencegahan karena Teluk Kendari merupakan pusat kegiatan di Sulawesi Tenggara. Penelitian selanjutnya seperti pengumpulan data geoteknik kelautan dan lingkungan sangat diperlukan untuk dijadikan data dasar untuk rencana pengembangan.