scholarly journals Prediksi Akumulasi Sedimen Berdasarkan Survei Batimetri dan Hidrodinamika di Pesisir Teluk Mandeh, Kabupaten Pesisir Selatan, Sumatera Barat

2020 ◽  
Vol 23 (1) ◽  
pp. 105
Author(s):  
Guntur Adhi Rahmawan ◽  
Ulung Jantama Wisha ◽  
Wisnu Arya Gemilang ◽  
Ilham Ilham ◽  
Semeidi Husrin
Keyword(s):  
Sedimentation Rate ◽  
Flow Model ◽  
Sediment Accumulation ◽  
River Estuary ◽  
Distribution Patterns ◽  
Water Area ◽  
Dual Frequency ◽  
Weak Current ◽  
Single Beam ◽  
Sediment Volume

Mandeh Bay is a semi-enclosed water area that there are two main estuaries, Mandeh and Nyalo River estuary. Sedimentation issue has been gotten worse due to the massive development in coastal area. This study aims to determine the sediment accumulation within Mandeh bay and its distribution patterns. The measurement of sedimentation rate applied in the Mandeh and Nyalo Estuaries. Oceanography parameters (tides and currents) recorded for 30 days measurement. The thickness of sediment accumulation was predicted by applying single beam echosounder dual frequency. The calculation of sediment volume was done using frustum formula grid 10 x10 meters. Flow model approach was also simulated to depict the distribution pattern of sediment. The thickness of sediment accumulation categorized into five spatial categories that are 0-0,3m, 0,4-0,6m, 0,7-0,9,1-1,2m, and 1,3-1,5m. The sedimentation rate in Mandeh estuary ranged from 60,85 up to 62,16 g.m-2.day-1, while in Nyalo estuary is approximately 48,86 g.m-2.day-1. The tidal current speed that is weak ranged from 0-0,05 m/s induces the sediment accumulation which mainly occurs during the neap tidal conditions. The thickness of sediment accumulation which is more than one meter identified around Mandeh River estuary and several areas near Carocok Tarusan Port where the sediment intake takes place and due to the weak current feature, it causes the increase of sedimentation in this region.  Teluk mandeh merupakan kawasan teluk semi tertutup yang mempunyai 2 muara sungai besar yaitu sungai Mandeh dan sungai Nyalo. Masalah sedimentasi menjadi semakin parah karena pengembangan wilayah pesisir yang masif. Tujuan dari penelitian ini adalah untuk mengetahui ketebalan akumulasi sedimen di dalam Teluk Mandeh dan pola distribusinya. Pengukuran laju sedimentasi dilakukan pada dua fokus area yakni muara Sungai Mandeh dan Sungai Nyalo. Pengukuran parameter oseanografi (arus dan pasang surut) dilakukan selama 30 hari pengukuran. Ketebalan akumulasi sedimen diukur menggunakan alat Single Beam Echosounder Dual Frekuensi. Perhitungan volume sedimen dihitung dengan rumus frustum grid 10x10 meter. Simulasi flow model juga dilakukan untuk mengetahui pola distribusi sedimen. Sebaran ketebalan sedimen yang dibagi dalam 5 kategori spasial yakni 0-0,3m, 0,4-0,6m, 0,7-0,9,1-1,2m, dan 1,3-1,5m. Laju sedimentasi di muara Sungai Mandeh berkisar antara 60,85 sampai 62,16 g.m-2.hari-1 dan di muara Sungai Nyalo rata-rata 48,86 g.m-2.hari-1. Kecepatan arus pasang surut yang cukup lemah berkisar antara 0-0,05 m/s menyebabkan potensi akumulasi sedimen akan berlangsung terutama saat kondisi perbani. Sedimen dengan ketebalan lebih dari 1 meter teridentifikasi di sekitar Sungai Mandeh dan beberapa Kawasan Pelabuhan Carocok Tarusan dimana asupan sedimen mendominasi. Karena karakteristik arus yang lemah, sedimentasi meningkat diwilayah ini.

scholarly journals Sedimentation Rate and Sediment Accumulation at the Estuary of Rokan River, Indonesia

2020 ◽  
Vol 13 ◽  
pp. 1-10
Author(s):  
RIFARDI RIFARDI ◽  
Musrifin Galib
Keyword(s):  
Sedimentation Rate ◽  
River Sediment ◽  
Sediment Accumulation ◽  
Outer Part ◽  
River Estuary ◽  
Fine Silt ◽  
Sediment Samples ◽  
Sampling Points ◽  
Alpha Spectrometer

The objective of the study was to analyse the sedimentation rate and sediment accumulation at the estuary of the Rokan River. Sediment samples were collected from 3 sampling points, i.e. Southern, Western and Northern of Berkey Island. The samples were then analysed using 210Pb radioisotope of the alpha spectrometer. The bottom of the Rokan River estuary is dominated by fine silt. It was recorded that sedimentation rate in Southern, Western, and Northern of Berkey Island were 0.3, 0.22, and 0.28 cm/year, respectively. The accumulation of sediment in each station was as follows; 3.13, 2.88, and 3.42 ton/ha/year. The age of sediment in the Southern Berkey Island was 23,71 years at depth 14 cm, Western Berkey Island was 64,26 years, and in Northern Berkey Island was 26,59 years. Sedimentation rate inside was higher than outside of the estuary. Higher sediment accumulation was noted at the outer part of the estuary compared to the inner part. The sediments found in the central part of the estuary are older than those inside and outside.

DISTRIBUTION OF DISSOLVED CHEMICAL ELEMENTS IN THE YENISEI RIVER ESTUARY AND ADJACENT WATER AREA OF THE KARA SEA

2017 ◽  
Author(s):  
Alla Savenko ◽  
Alla Savenko ◽  
Oleg Pokrovsky ◽  
Oleg Pokrovsky ◽  
Irina Streletskaya ◽  
...  
Keyword(s):  
Trace Elements ◽  
River Runoff ◽  
Major Ions ◽  
Chemical Elements ◽  
River Estuary ◽  
Water Area ◽  
Kara Sea ◽  
Yenisei River ◽  
Adjacent Water ◽  
The Yenisei River

The distribution of dissolved chemical elements (major ions, nutrients, and trace elements) in the Yenisei River estuary and adjacent water area in 2009 and 2010 are presented. These results were compared to the data obtained during previous hydrochemical studies of this region. The transport of major cations (Na, K, Mg, Ca) and some trace elements (Rb, Cs, Sr, B, F, As, Mo, U) in the estuary follows conservative mixing. Alkalinity also belongs to conservative components, however this parameter exhibits substantial spatial heterogeneity caused by complex hydrological structure of the Yenisei Bay and adjoining part of the Kara Sea formed under the influence of several sources of desalination and salty waters inflow. Concentrations of Pmin, Si, and V in the desalinized waters of photic layer decrease seaward owing to uptake by phytoplankton. The losses of these elements reach 30–57, 30, and 9% of their supply by river runoff, respectively. The content of dissolved phosphates and vanadium in the intermediate and near-bottom layers of the Yenisei River estuary strongly increases with salinity due to regeneration of precipitated organic matter, whereas silica remineralization is much less pronounced. Barium is characterized by additional input of dissolved forms in the mixing zone in the quantity comparable to that carried out by river runoff. This may be caused by its desorption from river suspended matter due to ion exchange. The transport of dissolved Al and Mn in the estuarine zone is probably controlled by the coagulation and flocculation of organic and organomineral colloids, which is indicated by a decrease in the concentration of these elements at the beginning of the estuary (31 and 56%, respectively) followed by a stable concentration further seaward.

scholarly journals Acoustic characterization of seafloor habitats on the western continental shelf of India

2007 ◽  
Vol 64 (3) ◽  
pp. 551-558 ◽  
Author(s):  
Bishwajit Chakraborty ◽  
Vasudev Mahale ◽  
Gajanan Navelkar ◽  
B. Ramalingeswara Rao ◽  
R. G. Prabhudesai ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Dual Frequency ◽  
Scattering Process ◽  
Backscatter Signal ◽  
Sediment Volume ◽  
Interface Scattering ◽  
Acoustic Characterization ◽  
Power Law Exponent ◽  
Different Grain Size

Abstract Chakraborty, B., Mahale, V., Navelkar, G., Rao, B. R., Prabhudesai, R. G., Ingole, B., and Janakirinam, G. 2007. Acoustic characterization of seafloor habitats on the western continental shelf of India. – ICES Journal of Marine Science, 64: 551–558. This is a study of the interaction effects of the dual-frequency (210 and 33 kHz) backscatter signal with seafloor sediment and benthic biota along a transect in water 27–83 m deep offshore of the Goa region of India's central west coast. Estimation of the power-law exponent using seafloor topographic data provided equivalent values even when using dual high-frequency systems for different grain-size sediments. Backscatter signals corrected from system-related gain, etc., reveal better correlations with sedimentary and benthic parameters than the estimated coherence parameters (using echo peaks). Statistically, correlations are significant for the 210 kHz backscatter signal with sand and calcium carbonate (CaCO3) sediment content. Also, correlations are higher for macrobenthic biomass (wet weight) and population density with a 210 kHz backscatter strength, emphasizing the dominant seawater–seafloor interface scattering process. For 33 kHz backscatter strength, the absence of such correlations indicates a different scattering process, i.e. dominant sediment volume scattering attributable to the comparatively lower signal attenuation. Additionally, to validate the results, the backscatter signals from other locations in the vicinity of this transect were considered.

scholarly journals TAXAS DE ASSOREAMENTO E A INFLUÊNCIA ANTRÓPICA NO CONTROLE DA SEDIMENTAÇÃO DA BAÍA DE ANTONINA - PARANÁ

2003 ◽  
Vol 53 ◽  
Author(s):  
Lydio Luiz Rissetti Odreski ◽  
Carlos Roberto Soares ◽  
Rodolfo José Angulo ◽  
Rafaela Cristine Zem
Keyword(s):  
Sedimentation Rate ◽  
Historical Survey ◽  
River Catchment ◽  
Serra Do Mar ◽  
Sediment Volume ◽  
Significant Acceleration ◽  
Catchment Areas ◽  
Periodic Maintenance ◽  
Anthropic Influence ◽  
Total Sediment

A manutenção dos canais de navegação que acessam os portos organizados de Paranaguá e Antonina, por meio das operações de dragagens e despejo de material dragado, constituem uma atividade onerosa para os portos e impactante para o meio ambiente. Este estudo procurou oferecer uma contribuição ao conhecimento da dinâmica batimétrica da Baía de Antonina, correlacionando levantamentos históricos de batimetria com dados mais recentes. O resultado desta comparação evidenciou um intenso assoreamento da Baía de Antonina, principalmente na porção superior e nas margens, onde se constatou progradação das planícies de maré. O volume de sedimento depositado no período entre 1901 e 1979 foi cerca de 60 x 10 (elevado a 6) m3 , caracterizando uma taxa de sedimentação de aproximadamente 2,6 cm/ano. A influência antrópica exercida pela interligação das bacias de drenagem dos rios Capivari e Cachoeira para a construção de uma usina hidroelétrica, do desmatamento da Serra do Mar na região das cabeceiras dos rios e das atividades de dragagens e despejo de material dragado, parece ter tido uma contribuição significativa na aceleração do processo de colmatação deste setor do Complexo Estuarino de Paranaguá. SILTING RATE AND THE ANTHROPIC INFLUENCE ON THE SEDIMENTATION PROCESS OF ANTONINA BAY - PARANÁ Abstract The maritime channel that yields access to Paranaguá and Antonina harbours requires periodic maintenance of its security maritime depth. That maintenance requires dredging and disposal operations. This study aims at increasing the knowledge of the bathymetric dynamics of Antonina Bay, correlating historical survey data to actual data. The results of this comparison show an intense shoaling on Antonina Bay, mainly on the upper portion and on the margins, where extensive tidal flats have developed. The total sediment volume deposited in the period between 1901 and 1979 was around 60 x 10 (raised the 6) m3 , reflecting a sedimentation rate of approximately 2,6 cm/year. Anthropic influence such as the connection between the rivers Capivari and Cachoeira for hydroelectric purposes, deforestation on river catchment areas at Serra do Mar, and activities of dredging and disposal, hints at a significant acceleration of the silting process of this portion of the Paranaguá Bay Estuarine Complex.

scholarly journals Icebergs in the Southern Ocean (Abstract)

1987 ◽  
Vol 9 ◽  
pp. 241-242 ◽  
Author(s):  
Olav Orbeim
Keyword(s):  
Southern Ocean ◽  
Continental Shelf ◽  
Distribution Patterns ◽  
Water Area ◽  
Standard Size ◽  
Data Set ◽  
Radar Observations ◽  
Image Position ◽  
The Antarctic ◽  
Size Data

Relatively little data on the distribution of Antarctic icebergs were available prior to 1980. The published literature included size data of about 5000 icebergs, and position data of 12 000 icebergs. There were indications that the size data were biased in favour of larger icebergs. A programme of systematic iceberg observations was therefore initiated by Norsk Polarinstitutt in 198! through the SCAR Working Group on Glaciology. This programme is based on standard “blue” forms distributed to all ships going to Antarctica. The icebergs are recorded every 6 h and in Five length groups: 10–50, 50–200, 200–500, and 500–1000 m, and those over 1000 m are described individually. The amount of data has increased greatly from the start in 1981–82. The position of 70 000 icebergs, including 50 000 that had been size classified, were on file at Norsk Polarinstitutt by December 1985, and the data set is growing rapidly. Most ships travelling to and from Antarctica now participate in collection of the data. (Fig.1 shows the locations of the icebergs sighted.) Fig. 1. Location of iceberg observations under the programme initiated in 1981. Main ship tracks are clearly reflected. The average observation represents 14 icebergs. The size distribution of the classified icebergs observed under this programme up to December 1985 is given in Table I: Table I The “standard size” (length, width, and thickness) is based on our observations from three Antarctic expeditions which carried out dedicated iceberg studies. Many icebergs are of course not right-angled parallelepipedal in shape, but this is a good approximation for most of the larger icebergs. The data are based both on visual sightings and on radar observations. Duplicate observations from a ship moving at slow or zero speed are as far as possible eliminated, both during observation, and by critical appraisal before the data are filed. The data editing also includes evaluation of data quality, especially in connection with radar observations, and comparison of positions and dimensions of the large icebergs in order to reduce to a minimum repeated observations from different vessels of icebergs >1000 m. These account for most of the iceberg mass (see Table I). Consideration of iceberg-distribution patterns and the observed area of the Southern Ocean, and of duplicate observations, indicates more than 300 000 icebergs south of the Antarctic Convergence, with a total ice mass of about 1016 kg. Consideration of mean residence times indicates an annual iceberg production from the continent of 23–1015 kg, which is considerably higher than most other recent estimates. This also suggests that the Antarctic ice sheet is in balance. The data indicate large regional differences in iceberg sizes, the most noticeable being between the two sides of the Antarctic Peninsula, and between the Amery Ice Shelf/ Prydz Bay area and the remainder of East Antarctica. These differences are probably mainly related to different calving sites. About one-third of the observed icebergs are over the continental shelf of Antarctica. The total under-water area of these icebergs is two orders of magnitude less than the under-water area of the Antarctic ice shelves. The annual total iceberg melting and its effect on the water masses over the continental shelf has been calculated from ocean-water temperature variations at 200 m depth and estimated melt rates. This turns out to be an order of magnitude less than the annual effect of melting sea ice. The iceberg data considered here are probably under-represented with respect to the smallest sizes, and they do not include icebergs that have become <10 m. Inclusion of these ice bodies would increase the total melt.

Global wind-induced change of deep-sea sediment budgets, new ocean production and CO 2 reservoirs ca . 3.3-2.35 Ma BP

1988 ◽  
Vol 318 (1191) ◽  
pp. 487-504 ◽  
Keyword(s):  
Large Scale ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Distribution Patterns ◽  
Trade Wind ◽  
Accumulation Rates ◽  
Deep Sea Sediment ◽  
Late Pliocene ◽  
High Productivity ◽  
Sediment Fraction

The late Pliocene phase of large-scale climatic deterioration about 3.2-2.4 Ma BP is well documented in a number of (benthic) δ 18 O records. To test the global implications of this event, we have mapped the distribution patterns of various sediment variables in the Pacific and Atlantic Oceans during two time slices, 3.4-3.18 and 2.43-2.33 Ma BP. The changes of bulk sedimentation and bulk sediment accumulation rates are largely explained by the variations of CaCO 3 -accumulation rates (and the accumulation rates of the complementary siliciclastic sediment fraction near continents in higher latitudes). During the late Pliocene, the CaCO 3 -accumulation rate increased along the equatorial Pacific and Atlantic and in the northeastern Atlantic, but decreased elsewhere. The accumulation rate of organic carbon (C org ) and net palaeoproductivity also increased below the high-productivity belts along the equator and the eastern continental margins. From these patterns we may conclude that (trade-) wind- induced upwelling zones and upwelling productivity were much enhanced during that time. This change led to an increased transfer of CO 2 from the surface ocean to the ocean deep water and to a reduction of evaporation, which resulted in an aridification of the Saharan desert belt as depicted in the dust sediments off northwest Africa.

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