Karakteristik Morfologi Dasar Laut dan Hubungannya dengan Ketebalan Sedimen dan Kecepatan Arus di Selat Flores, Selat Lamakera, Selat Boling, dan Selat Alor

2017 ◽  
Vol 2 (2) ◽  
pp. 11
Author(s):  
Muhammad Hasanudin
Keyword(s):  
Current Speed ◽  
High Current ◽  
Sediment Thickness ◽  
Single Beam ◽  
Sedimentary Deposits ◽  
Sea Bottom ◽  
Subbottom Profiler

<strong>Characteristics of Sea Bottom Morphology and Their Relationships with Sediment Thickness and Current Speed in the Straits of Flores, Lamakera, Boling, and Alor. </strong> The morphology of the seabed of a strait may affect sedimentary deposits and current speeds in the strait. The Straits of Flores, Lamakera, Boling, and Alor connect the Flores Sea and Savu Sea in East Nusa Tenggara Province. This study aimed to determine the characteristics of seabed morphology and its relation to sediment thickness and current speed in the straits. Single Beam Echosounder and SubBottom Profiler were used to measure depth of waters and subsurface. The results showed that the seabed of the Flores Strait was basin-shaped at a depth of about 250 m, while the seabed at the connections between the Straits of Boling, Lamakera, and Alor was a ridge leading to the Flores Sea and Savu Sea with depths up to 3,000 m. The thickness of the sedimentary sediments in the Flores Strait reached 50 m, while in the Straits of Boling, Lamakera, and Alor sedimentary deposits were not visible. In the Flores Strait which was characterized by narrow strait, the current speed ranged from 0.3 to 3.8 m/s. The descriptions of subsurface conditions in these straits can be used for navigation of ships that will cross the straits, especially vessels of more than 2,000 tons. The narrow strait morphology causes the mass of water in this region to have a high current speed. Therefore, the sedimentation occurs only in the Flores Strait due to its basin-shaped seabed.

Contextualized sedimentation rates for large floods along the lower Mississippi River: the importance of flood duration

2021 ◽  
Author(s):  
Paul Hudson ◽  
Franklin Heitmuller ◽  
Samuel Muñoz ◽  
Jansen Costello
Keyword(s):  
Suspended Sediment ◽  
Sedimentation Rate ◽  
Field Data ◽  
Flood Events ◽  
Sediment Thickness ◽  
Flood Duration ◽  
Sedimentary Deposits ◽  
Sand Sheet ◽  
Overbank Sedimentation ◽  
Sampling Procedures

&lt;p&gt;Flood sedimentary deposits vary due to upper basin and lower basin controls. In this study we focus on overbank sediment thickness, which over longer periods drives changes to riparian aquatic habitat and floodplain construction. The study setting is a ~25 km long segment of the lower Mississippi alluvial valley, between Natchez, MS and Red River Landing, LA. We report new field data for overbank sedimentation generated by compound flooding over 2018 and 2019 hydrologic years, and compare with sedimentation data from prior large flood events. Overbank conditions in 2018 and 2019 persisted for 286 days (at Natchez, MS). During the 2019 hydrologic year the Mississippi was overbank for a record duration of 216 days, resulting in a much greater duration of overbank sedimentation than the 2011 (53 days) and 1973 (90 days) flood events.&lt;/p&gt;&lt;p&gt;The thickness of overbank deposits are reported for 48 field sites across a range of depositional environments typical of large lowland meandering river floodplains. Flood deposits were sampled in October 2019 using conventional field sampling procedures, including sedimentation traps (artificial grass mats installed in October 2017) and recognition of recent sediment deposited atop buried organic layers. The thickness of each reported sample is an average of three measurements obtained at each field site.&lt;/p&gt;&lt;p&gt;The average thickness of flood deposit samples over 2018-2019 hydrologic years is 71 mm, with variability according to distance from channel and floodplain depositional environment. Maximum sedimentation was associated with crevasse (750 mm) and sand sheet (1,430 mm) deposition along the crest of natural levees. Sedimentation thickness decreases within ~250 m of the channel, but remains high at a distance of ~3.5 km (30 mm). Beyond the range of sand sheet deposition, overbank deposition is likely influenced by variability in floodplain hydrology and geomorphology across natural levee (181 mm), meander scroll (30 mm), old channel (77 mm), and backswamp (108 mm) environments. High backswamp sedimentation at the study site is likely influenced by historic hydraulic engineering for flood control, which has altered local sedimentation patterns.&lt;/p&gt;&lt;p&gt;The 2018-2019 sedimentation data are contextualized by comparison with field data from the record 2011 magnitude flood (peak Q of 65,978 m&lt;sup&gt;3&lt;/sup&gt;/s at Vicksburg, MS, USGS 0728900) and the historic 1973 flood (55,558 m&lt;sup&gt;3&lt;/sup&gt;/s). &amp;#160;Average sediment thickness for the 2011 and 1973 overbank deposits was 42 mm (n=49) and 230 mm (n=31), respectively. The 2018-2019 daily sedimentation rate (0.25 mm/day) is much less than 2011 (0.75 mm/day). Thus, the much thicker sedimentary deposits for the 2018-2019 events suggests the greater importance of flood duration &amp;#8211; rather than flood magnitude &amp;#8211; to overall floodplain processes and alluvial fill chronologies along lowland rivers. The much lower flood sedimentation rate for 2018-2019 in comparison with 1973 (2.49 mm/day) may reveal the persistent decline in Mississippi suspended sediment loads since the early 1950s. Study results are further contextualized by considering corresponding event-based discharge &amp;#8211; suspended sediment dynamics, sediment province, as well as flood hydroclimatology.&lt;/p&gt;

III.—On the Original Form of Sedimentary Deposits

1903 ◽  
Vol 10 (1) ◽  
pp. 12-18 ◽  
Author(s):  
J. F. Blake
Keyword(s):  
Essential Elements ◽  
Original Form ◽  
Sedimentary Deposits ◽  
Sea Bottom ◽  
Theoretical Considerations ◽  
Theoretical Results

The form of the deposits that are taking place on the sea-bottom at the present day is one of the essential elements required to be known when we wish to interpret the submarine contours, as throwing light on the submergence or elevation of the land in late geological times, or when we propose to use the variation of thickness of the strata deposited during any epoch as an indication of the position of the shore-lines at that time.In the case of deposits in small or temporary masses of water, their form and arrangement may sometimes be observed directly; but in the case of the deposits in the sea, where we can neither remove the water nor make borings beneath it, we can only avail ourselves of theoretical considerations.It might have been expected that the original form of various sedimentary deposits would have been considered in detail long ago, but as a matter of fact the few writers who have touched upon the question have mostly been content with the assumption that deposits taken as a whole are thickest near the source of supply, and the figures given in illustration of the arrangement of various kinds, and thereby the shape of each, are remarkable for their variety.As the theoretical results at which I have arrived differ fundamentally from the ordinary assumptions, it is to be hoped that some one will be able to point out the fallacy, if any, which has led me astray, and to explain more satisfactorily the observed features which appear to confirm the theory.

scholarly journals Four Current Meter Models Compared in Strong Currents in Drake Passage

2013 ◽  
Vol 30 (10) ◽  
pp. 2465-2477 ◽  
Author(s):  
D. Randolph Watts ◽  
Maureen A. Kennelly ◽  
Kathleen A. Donohue ◽  
Karen L. Tracey ◽  
Teresa K. Chereskin ◽  
...  
Keyword(s):  
Drake Passage ◽  
Current Speed ◽  
The Other ◽  
High Current ◽  
Velocity Measurements ◽  
Time Intervals ◽  
Current Events ◽  
The Mean ◽  
Reference Measurements ◽  
Mean Current

Abstract Seven current meters representing four models on a stiffly buoyed mooring were placed for an 11-month deployment to intercompare their velocity measurements: two vector-measuring current meters (VMCMs), two Aanderaa recording current meter (RCM) 11s, two Aanderaa SEAGUARDs, and a Nortek Aquadopp. The current meters were placed 6-m apart from each other at about 4000-m depth in an area of Drake Passage expected to have strong currents, nearly independent of depth near the bottom. Two high-current events occurred in bursts of semidiurnal pulses lasting several days, one with peak speeds up to 67 cm s−1 and the other above 35 cm s−1. The current-speed measurements all agreed within 7% of the median value when vector averaged over simultaneous time intervals. The VMCMs, chosen as the reference measurements, were found to measure the median of the mean-current magnitudes. The RCM11 and SEAGUARD current speeds agreed within 2% of the median at higher speeds (35–67 cm s−1), whereas in lower speed ranges (0–35 cm s−1) the vector-averaged speeds for the RCM11 and SEAGUARD were 4%–5% lower and 3%–5% higher than the median, respectively. The shorter-record Aquadopp current speeds were about 6% higher than the VMCMs over the range (0–40 cm s−1) encountered.

III.—Notes on “The Great Ice Age” in Relation to the Question of Submergence

1895 ◽  
Vol 2 (8) ◽  
pp. 348-351
Author(s):  
Dugald Bell
Keyword(s):  
Ice Age ◽  
Marine Life ◽  
Sedimentary Deposits ◽  
Sea Bottom ◽  
Boulder Clay

“Even if marine life had been prolific, and the old sea-bottom more or less well covered with sedimentary deposits, it does not follow,” says Dr. Geikie, “that the Boulder-clay of the succeeding mer de glace should now contain any shells” (p. 141).

Sea-bottom classification across a shallow-water bar channel and near-shore shelf, using single-beam acoustics

2005 ◽  
Vol 65 (4) ◽  
pp. 625-632 ◽  
Author(s):  
Rosa Freitas ◽  
Leandro Sampaio ◽  
Ana Maria Rodrigues ◽  
Victor Quintino
Keyword(s):  
Shallow Water ◽  
Single Beam ◽  
Sea Bottom ◽  
Near Shore ◽  
Bottom Classification

scholarly journals KONDISI GEOMORFOLOGI DAN KARAKTERISTIK SEDIMEN DASAR LAUT DI WILAYAH PERAIRAN SEBAGIN UNTUK EVALUASI TAPAK PLTN DI BANGKA SELATAN

2015 ◽  
Vol 17 (2) ◽  
pp. 97
Author(s):  
Yuliastuti Yuliastuti ◽  
Heni Susiati ◽  
Yarianto Sugeng Budi Susilo
Keyword(s):  
Bottom Sediment ◽  
Water Intake ◽  
Depth Range ◽  
Sediment Characteristics ◽  
Single Beam ◽  
Sea Bottom ◽  
Sea Bed ◽  
The Stability ◽  
Result Analysis ◽  
Echo Sounder

ABSTRAK KONDISI GEOMORFOLOGI DAN KARAKTERISTIK SEDIMEN DASAR LAUT DI WILAYAH PESISIR PERAIRAN SEBAGIN UNTUK EVALUASI TAPAK PLTN DI BANGKA SELATAN. Telah dilakukan penelitian mengenai kondisi geomorfologi dan karakteristik sedimen dasar laut di wilayah perairan sebagian, Bangka Selatan. Informasi geomorfologi dasar laut sangat berguna dalam hal interpretasi struktur-struktur geologi yang berada di dasar laut. Sedangkan informasi karakteristik sedimen dasar laut bermanfaat untuk memberikan gambaran perlapisan batuan dasar laut dalam kaitannya dengan kestabilan tapak PLTN terkait aspek kegempaan dan penentuan posisi water intake. Penelitian ini bertujuan untuk mengevaluasi kondisi geomorfologi dan karakterisasi sedimen dasar laut di perairan Sebagin, Bangka Selatan. Metodologi yang dipakai untuk mengevaluasi kondisi geomorfologi dasar laut adalah Multi Beam Echo Sounder (MBES) dan Single Beam Echo Sounder (SBES). Sedangkan untuk karakterisasi sedimen dasar laut dilakukan dengan pengukuran seismik refleksi resolusi tinggi menggunakan sub bottom profiling (SBP) dan uji sampel sedimen di daerah penelitian. Hasil penelitian menunjukkan bahwa daerah penelitian merupakan perairan dangkal dengan kedalaman 1- 59 m. Profil geomorfologi dasar laut daerah penelitian cenderung tidak beraturan dan berdasarkan interpretasi seismik tidak ditemukan adanya patahan. Hasil analisis sedimen dasar laut menunjukkan bahwa, distribusi lumpur mendominasi daerah perairan calon tapak PLTN. Kata Kunci : geomorfologi, tapak PLTN, sedimen, sub bottom profile.   ABSTRACT GEOMORPHOLOGICAL CONDITION AND SEA BOTTOM SEDIMENT CHARACTERISTICS OF SEBAGIN COAST FOR NPP SITE EVALUATION IN SOUTH BANGKA. Study on geomorphological condition and sea bottom sediment in the coastal area of Sebagin, South Bangka Regency, Bangka Belitung Province has been performed. Geomorphological of the seabed was valuable to identify geological structures that exist on the seabed layers. Whereas, sediments seabed characteristics was useful to provide portrait of seabed layer due to the stability of NPP site concerning the seismic aspect and the determination of water intake position. The objective of the study was to evaluate geomorphological condition and sea bed sediment characteristics in the South Bangka sea. Methodology used for evaluating geomorphological of the sea bed were Multi Beam Echo Sounder (MBES) and Single Beam Echo Sounder (SBES). While for sea bottom sediment characteristics, SBP together with sediment sample analysis were used. The result of the study showed that the study area was a shallow water sea with a depth range of 1-59 m. Geomorphological profile of the sea bed tend to be irregular and based on the seismic interpretation, there were no fault exists. Result analysis on the sea bottom sediment showed that clay distribution dominated the study area. Keywords: geomorphology, NPP site, sediment, sub bottom profile.

scholarly journals PENENTUAN LOKASI TURBIN PEMBANGKIT LISTRIK TENAGA ARUS LAUT SKALA KECIL DI PERAIRAN SELAT LIRUNG, TALAUD, SULAWESI UTARA

2016 ◽  
Vol 13 (3) ◽  
pp. 127 ◽  
Author(s):  
Beben Rachmat ◽  
Delyuzar Ilahude
Keyword(s):  
Data Analysis ◽  
Current Speed ◽  
Small Scale ◽  
Energy Potential ◽  
Sea Bottom ◽  
Strong Current ◽  
Maximum Current ◽  
Sea Current ◽  
Marine Current ◽  
Marine Currents

Selat Lirung adalah selat yang terletak antara Pulau Salibabu dan Pulau Karakelong, Kepulauan Talaud. Penelitian potensi energi arus laut telah dilakukan di lokasi ini, untuk mengkaji kemungkinan dikembangkannya Pembangkit Listrik Tenaga Arus Laut (PLTAL) skala kecil (2 kW) dengan model turbin sumbu vertikal. Salah satu tahapan dalam implementasi PLTAL skala kecil adalah penentuan lokasi penempatan turbin. Beberapa kriteria teknis yang dipersyaratkan harus dipenuhi pada tahapan ini. Untuk maksud tersebut dilakukan kajian awal dengan melakukan analisis data kedalaman laut, Sea Bottom Profiling (SBP), arus bergerak, arus insitu, pasang surut, dan meteorologi. Data tersebut direpresentasikan dalam data kecepatan arus laut, morfologi dasar laut, kedalaman laut, durasi waktu kecepatan arus kuat, jarak terhadap garis pantai, dan pengaruh gelombang laut. Berdasarkan hasil analisis data tersebut diperoleh 2 (dua) lokasi yang paling representatif. Lokasi pertama di alur antara P. Sara Besar dengan Sara Kecil pada kedalaman laut sekitar 25 m dengan kecepatan arus maksimum sebesar 1.0 m/det-1.75 m/det. Sedangkan lokasi kedua di alur antara P. Sara Besar dengan P. Salibabu pada kedalaman laut antara 25 m-35 m dengan kecepatan arus maksimum sebesar 1.0 m/det-1.3 m/det. Kata kunci Tenaga arus laut, turbin, kecepatan arus, morfologi dasar laut, kedalaman laut The Lirung Strait is a strait located between the Salibabu Island and Karakelong Island, Talaud. Energy potential of marine current research has been done in this location, to examine the possibility of the development of Marine Current Power Plant (MCPP) small scale (2 kW). One of the stages in the implementation of MCPP small scale is determining the location of the turbines placement. Some technical criteria required to be met at this stage. For the purpose of initial studies to perform data analysis depth of the sea, Sea Bottom Profiling (SBP), the current is moving, insitu currents, tides, and meteorology. That data are represented within the sea current speed, the morphology of the seabed, ocean depth, duration of strong current speed, distance to the coastline,and the influence of waves. Based on the results of the analysis of the data obtained two (2) most representative locations. The first location is in the groove between the Sara Besar Island with Sara Kecil Island at the depths between 25 m with the maximum current speed of 1.0 m/s-1.75 m/s. The second location is in the groove between the Sara Besar Island with Salibabu Island at the depths between 25 m - 35 m with the maximum current speed of 1.0 m/s-1.3 m/s. Keywords: Power of marine currents, turbines, current speed, seabed morphology, ocean depths

Electronic Sector-scanning Asdic

1959 ◽  
Vol 12 (2) ◽  
pp. 184-189 ◽  
Author(s):  
D. G. Tucker
Keyword(s):  
High Speed ◽  
Acoustic Energy ◽  
Single Beam ◽  
Left Hand ◽  
Pulse Transmission ◽  
Sea Bottom ◽  
Maximum Range ◽  
Acoustic Echo ◽  
Very High ◽  
Wide Sector

A new system of electronic scanning is described in which the narrow receiving beam of an acoustic echo-ranging equipment (i.e. asdic) is swept over a wide sector at a very high speed. Since the transmitted pulse covers the whole sector, and the scanning is done at least once per pulse duration, an effectively instantaneous search of the sector is made without any loss of information. The results of trials at sea are shown and possible applications to surveying and navigation are briefly discussed.The use of underwater acoustic echo-ranging systems in the form of echo-sounders (as fitted on most ships nowadays) and asdics (as used, for example, for submarine detection during the war and now applied to whale-finding and fish-finding) is well-known.1 These existing systems use a single beam of acoustic energy, the pulse being transmitted by a transducer (or loudspeaker), and received, after reflection from the sea-bottom or whale or other object, by the same or a different transducer (this time used as a microphone). The time difference between transmitted and received pulses measures the range of the bottom or object, and is recorded on a chart by a stylus moving at a speed equal to the velocity of sound in water multiplied by the ratio of the width of the chart to twice the maximum range of detection. The transmission of the pulse marks the left-hand edge of the paper, and any echo received causes a mark at a point in the stylus sweep corresponding to the range of the object causing the echo. The paper is meanwhile moving at right angles to the stylus sweep, so that the next pulse transmission marks on a line adjacent to the previous one.

scholarly journals Investigations of the sediment thickness in Søndre Strømfjord, West Greenland

1977 ◽  
Vol 85 ◽  
pp. 47-48
Author(s):  
B Larsen
Keyword(s):  
Sea Level ◽  
Outer Part ◽  
Sediment Thickness ◽  
West Greenland ◽  
Innermost Part ◽  
North East ◽  
Sea Bottom ◽  
Glacial River ◽  
Glacial Processes ◽  
Base Data

Søndre Strømfjord, approximately 170 km long, is a very clear example of a fjord formed by glacial processes. The bottom of the outer part ofthe fjord is U-shaped and situated only a few tens of metres below sea level. In the inner half of the fjord, north-east of Sarfartoq, the fjord is about 280 m deep and the sea bottom nearly horizontal for at least 40 km. In the innermost part the bottom rises towards the large glacial river near the air base (data from Danish nautical charts nos. 1410, 1411, 1412).

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