scholarly journals Karakteristik Perubahan Lingkungan Akhir Plistosen - Holosen di Dataran Rendah Aluvial dan Pantai Wilayah Demak, Kudus, Jepara, Pati dan Sekitaranya

2021 ◽  
Vol 12 (1) ◽  
pp. 17
Author(s):  
Rio A.T. Moechtar ◽  
Subiyanto Subiyanto ◽  
R.I.H Sulistyawan
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Depositional Environment ◽  
Deposition Process ◽  
Alluvial Plain ◽  
Sea Level Fluctuations ◽  
Stratigraphic Analysis ◽  
External Process ◽  
Holocene Sediments ◽  
Sea Level Fluctuation

ABSTRAKWilayah dataran aluvial hingga pantai daerah Demak, Kudus, Jepara, Pati dan sekitarnya ditutupi endapan sedimen Holosen yang terdiri atas kerikil, pasir, lempung, lanau, dan bongkah batuan gunungapi. Penelitian dilakukan dengan analisis sedimentologi dan stratigrafi terhadap 37 pemboran berskala 1 : 100 dengan ketebalan sedimen antara 0,8 - 18 meter. Berdasarkan korelasi data hasil pemboran diketahui bahwa sedimen Holosen di wilayah ini dapat dibedakan dalam tiga interval proses pengendapan (IPP A- C). Perubahan sedimen secara vertikal dapat diwakili oleh setiap sub-IPP yang merupakan hasil dari proses eksternal sesuai perubahan iklim, fluktuasi muka laut, tektonik dan aktivitas gunungapi. Dari hasil analisis stratigrafi diketahui bahwa perubahan lingkungan pengendapan pada daerah penelitian berhubungan dengan aktivitas proses eksternal di cekungan ini. Peranan proses eksternal ini diharapkan menjadi variabel dalam perumusan kebijakan pengelolaan lingkungan di wilayah Demak, Kudus, Jepara, Pati, dan sekitarnya.Kata kunci: fluktuasi muka air laut, Holosen, lingkungan, tektonik, perubahan iklimABSTRACTThe alluvial plain to the coast of Demak, Kudus, Jepara, Pati, and its surroundings is covered with sedimentary Holocene deposits consisting of gravel, sand, clay, silt, and volcanic rock boulders. The study used sedimentology and stratigraphic analysis of 37 drilling points with sediment thicknesses between 0.8-18 meters. Based on the correlation of drilling results, the Holocene sediments in the area of research can be distinguished in three deposition process (IPP) intervals. Vertically, sediment changes can be represented by each sub-IPP which are the result of external processes according to climate change, sea-level fluctuations, tectonics, and volcanic activity. From the results of the stratigraphic analysis, the changes in the depositional environment in the study area are related to external process activities in the basin. The effects of this external process are expected to be a recommendation in the future environmental development in the Demak, Kudus, Jepara, Pati, and its surroundings.Keywords: sea-level fluctuation, Holocene, environment, tectonic, climate change

scholarly journals Analysis of moored ship oscillations in waves

2020 ◽  
Author(s):  
Д.П. Ковалев ◽  
П.Д. Ковалев ◽  
А.С. Борисов
Keyword(s):  
Dynamic System ◽  
Sea Level ◽  
Order Differential Equation ◽  
External Excitation ◽  
Impact Oscillator ◽  
Mooring Lines ◽  
Sea Level Fluctuations ◽  
Port Area ◽  
Sea Level Fluctuation ◽  
The Impact

В работе рассмотрены особенности колебаний пришвартованного судна для основных портов Сахалинской области, поскольку качка судна у причала может представлять опасность и приводить к повреждению судна или швартовых линий. По данным натурных измерений морского волнения в портовых бухтах рассчитаны спектры колебаний уровня и определены периоды существующих в них волн для диапазона периодов от 2 с до 30 минут. Произведен расчет периодов собственных колебаний (качки) двух типов судов, преимущественно швартующихся в портах. С учетом полученных результатов выполнено моделирование движения судов при волнении как динамической с системы внешним возбуждающим воздействием на основе дифференциального уравнения второго порядка. Показано влияние коэффициента вязкого демпфирования и жесткости швартовых на реакцию динамической системы без удара о причал и для режима ударного осциллятора. Установлено, что в случае прихода в район порта Корсаков длинноволновой зыби движения судна могут переходить в хаотические. The paper considers the peculiarities of moored vessel oscillations for the main ports of the Sakhalin region, since the pitching of the vessel at the berth can be dangerous and lead to damages of the vessel or mooring lines. Spectra of sea level fluctuations and periods of waves in port bays were calculated using sea level fluctuation measurements obtained in the range from 2 seconds to 30 minutes. Calculations of resonance periods (pitching) of two types of vessels mainly moored in ports were done. Taking into consideration these results the simulation of the vessel movement in waves as a dynamic system with an external excitation was performed on the base of second-order differential equation. The influence of viscous damping coefficient and mooring stiffness on the response of the dynamic system is shown for two cases: for system without impact and for the impact oscillator mode. It is established that in the event of a long-wave swell coming to the Korsakov port area, the vessels movements may become chaotic.

Latest Pliensbachian–Toarcian eustatic calibration using shallow-marine sedimentological record coupled with basinal geochemical analyzes

2020 ◽  
Author(s):  
François-Nicolas Krencker ◽  
Alicia Fantasia ◽  
Mohamed El Ouali ◽  
Lahcen Kabiri ◽  
Stéphane Bodin
Keyword(s):  
Sea Level ◽  
Special Focus ◽  
Level Fluctuation ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sequence Stratigraphic ◽  
Sea Level Fluctuations ◽  
Anoxic Events ◽  
Chemical Index Of Alteration ◽  
Sea Level Fluctuation

<p><span>Sea-level fluctuation is an important parameter controlling the sedimentation in deep-marine environments and influenced also the expansion of oxygen-depleted conditions in neritic settings during oceanic anoxic events (OAEs). Despite this fundamental role, sea-level fluctuation remains on a short timescale (<1 Myr) one of the least constrained parameters for numerous OAEs. Here we refine the sequence stratigraphic framework for the uppermost Pliensbachian–Toarcian with a special focus on the Toarcian OAE interval. This study is based on sedimentological and total organic carbon isotope data used to correlate 16 sections located in the central High Atlas (Morocco). Palinspastically, those sections formed a 50-kilometer proximal–distal transect along the northern Gondwana continental shelf, which allow reconstructing the shoreline migration through time and space. Our sequence stratigraphic interpretation is then compared to the geochemical signals (e.g. detrital index, chemical index of alteration) measured on samples collected in deep-environment settings from numerous basins distributed worldwide. Our study shows that the relative sea-level changes recorded in Morocco can be correlated over large distances across those basins, indicating that the relative sea-level changes were driven by eustatic fluctuations. This study gives insights into the relationship between relative sea-level fluctuations and the geochemical record.</span></p>

scholarly journals The use of piezocone tests for high-resolution stratigraphy of Quaternary sediment sequences in the Brazilian coast

2007 ◽  
Vol 79 (1) ◽  
pp. 153-170 ◽  
Author(s):  
Giuliano de Mio ◽  
Heraldo L. Giacheti
Keyword(s):  
Sea Level ◽  
Sedimentary Environment ◽  
Brazilian Coast ◽  
Level Fluctuation ◽  
Test Results ◽  
Sea Level Fluctuations ◽  
Sedimentary Sequences ◽  
Sea Level Fluctuation ◽  
The Subject ◽  
Good Agreement

Correlations between mapping units of costal sedimentary basin and interpretation of piezocone test results are presented and discussed based on examples from Caravelas strandplain, (State of Bahia), Paranaguá (State of Paraná) and Guarujá bays (State of São Paulo), Brazil. Recognizing that the sedimentary environment was mainly controlled by sea level fluctuations led to the interpretation of transgressive and regressive sedimentary sequences, which is in a good agreement with the sea level fluctuation curves currently accepted for these regions. The interpretation of piezocone test results shows that the sedimentary sequences of Caravelas and Guarujá sites are similar and they have a good correlation to the sea level fluctuation curve accepted for Salvador region, State of Bahia. On the other hand, the piezocone test results from Paranaguá site indicate a different sedimentary sequence from the previous ones, relating to the sea level fluctuation curve accepted for Paranaguá region. The results show the high applicability of piezocone testing for stratigraphical logging and suggest that it is possible to integrate it with other current techniques used for paleo-environmental studies in Brazil, in accordance with recent approaches used in international research on the subject.

scholarly journals Beach-Foredune Sediment Budget Response to Sea Level Fluctuation. Curonian Spit, Lithuania

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 583 ◽  
Author(s):  
Darius Jarmalavičius ◽  
Donatas Pupienis ◽  
Gintautas Žilinskas ◽  
Rasa Janušaitė ◽  
Viktoras Karaliūnas
Keyword(s):  
Sea Level ◽  
Sediment Budget ◽  
Level Fluctuation ◽  
Curonian Spit ◽  
Decadal Time Scale ◽  
Beach Sediment ◽  
Minimal Impact ◽  
Sea Level Fluctuations ◽  
Sediment Volume ◽  
Sea Level Fluctuation

Beach-foredune sediment exchange maintains a coastal system’s stability. Sea level fluctuation is one of the most important factors that modifies the beach and foredune sediment budget. This study aims to assess beach and foredune sand budget changes depending on sea level fluctuations. On the basis of annual measurements of cross-shore profiles on the Curonian Spit in Lithuania, the sediment volumes on the beach and foredune and their changes between 2002 and 2019 were calculated. The sea level fluctuations were examined in parallel. The obtained data revealed that in the case of a sand surplus, a relatively low sea level rise does not have a significant impact on the development of a foredune (and a minimal impact on a beach) on a decadal time-scale. Short-term sea level fluctuations are reflected in year-to-year variability in a beach sediment budget. However, no significant relationship between year-to-year variability in sea level fluctuation and the foredune sediment budget has yet been identified, nor is there a reliable year-to-year variability relationship between the foredune and beach sediment budget. The foredune sediment budget remained positive both through an increase and a reduction in the sediment volume on the beach.

scholarly journals Turning the tide: comparison of tidal flow by periodic sea level fluctuation and by periodic bed tilting in scaled landscape experiments of estuaries

2017 ◽  
Vol 5 (4) ◽  
pp. 731-756 ◽  
Author(s):  
Maarten G. Kleinhans ◽  
Maarten van der Vegt ◽  
Jasper Leuven ◽  
Lisanne Braat ◽  
Henk Markies ◽  
...  
Keyword(s):  
Sea Level ◽  
Tidal Currents ◽  
Surface Flow ◽  
Water Levels ◽  
Tidal Range ◽  
Level Fluctuation ◽  
Tidal Period ◽  
Sea Level Fluctuations ◽  
Sediment Mobility ◽  
Sea Level Fluctuation

Abstract. Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the ebb and flood phase, causing dynamic channel and shoal patterns. However, it remains unclear whether tilting produces periodic flows with characteristic tidal properties that are sufficiently similar to those in nature for the purpose of landscape experiments. Moreover, it is not well understood why the flows driven by periodic sea level fluctuation, as in nature, are not sufficient for morphodynamic experiments. Here we compare for the first time the tidal currents driven by sea level fluctuations and by tilting. Experiments were run in a 20  ×  3 m straight flume, the Metronome, for a range of tilting periods and with one or two boundaries open at constant head with free inflow and outflow. Also, experiments were run with flow driven by periodic sea level fluctuations. We recorded surface flow velocity along the flume with particle imaging velocimetry and measured water levels along the flume. We compared the results to a one-dimensional model with shallow flow equations for a rough bed, which was tested on the experiments and applied to a range of length scales bridging small experiments and large estuaries. We found that the Reynolds method results in negligible flows along the flume except for the first few metres, whereas flume tilting results in nearly uniform reversing flow velocities along the entire flume that are strong enough to move sand. Furthermore, tidal excursion length relative to basin length and the dominance of friction over inertia is similar in tidal experiments and reality. The sediment mobility converges between the Reynolds method and tilting for flumes hundreds of metres long, which is impractical. Smaller flumes of a few metres in length, on the other hand, are much more dominated by friction than natural systems, meaning that sediment suspension would be impossible in the resulting laminar flow on tidal flats. Where the Reynolds method is limited by small sediment mobility and high tidal range relative to water depth, the tilting method allows for independent control over the variables flow depth, velocity, sediment mobility, tidal period and excursion length, and tidal asymmetry. A periodically tilting flume thus opens up the possibility of systematic biogeomorphological experimentation with self-formed estuaries.

The ancient city and the rising sea. Using archaeogeosites to convey climate awareness.

2021 ◽  
Author(s):  
Guido Stefano Mariani ◽  
Rita Teresa Melis
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Archaeological Site ◽  
Point Of View ◽  
Archaeological Heritage ◽  
Sea Level Fluctuations ◽  
Geological Processes ◽  
Ancient City ◽  
Surrounding Landscape ◽  
The City

<p>The interaction between human societies and the physical landscape is deep and widespread since the dawn of civilisation. The development of different cultures always had to take into account their physical and geological surrounding, in order to adapt to their features and exploit them in the most efficient fashion. Cultural and geological heritage are therefore often tightly linked in a relationship enhancing the meaning of both to society in many ways. Tapping into these cultural archives can provide a useful way of communicating geoheritage to the wider public through the history of human-landscape interactions. Such landmarks would effectively act as witnesses of Earth history from a human point of view and become beneficial in spreading knowledge about past and current geological processes such as climate change. With the help of archaeogeosites, integrated reconstructions where the geological and geomorphological evidence with the elements of archaeological heritage could provide an effective way of communicating to the larger public sea level dynamics at a longer scale and the effects of climate change in the present and near future.</p><p>As a case study, the late ancient city of Nora is particularly effective. Located in southwestern Sardinia (Italy), it was a seaport of great importance during the Punic and Roman periods. Its surrounding landscape is deeply influenced by the marine transgression happening since the Last Glacial Maximum. Along the coast, many landforms and stratigraphic sequences bear evidence of sea level fluctuations and the related changes in the landscape revealing the larger context in which the city was developed. Beach deposits dated to MIS5 are buried by fluvial deposits and soils indicating a much lower sea level during later stadial periods. Since the passage to the Holocene the area, dominated by fluvial and slope dynamics, is interested by the progressive rise of the coastline and the consequent land loss. The city itself was not spared from this process. While its strategic coastal position was instrumental in its rise to prominence, the exposure to a rising sea level had a great impact on its history, both during its development and later as an abandoned settlement and an archaeological site. Several human structures possibly show the necessity of shielding against a progressively more damaging wave action.</p>

Sign in / Sign up

Export Citation Format

Share Document