Indonesia Conference Directory

Corresponding Author
Afif Prabowo Jatiandana.

Institutions
(a) Oceanography_Earth Science Department, Faculty of Earth Science and Technology (FEST), Bandung Institute of Technology (ITB), Jl. Ganesha 10, Bandung 40132, Indonesia

*afifprabowoj[at]gmail.com
*afifpj[at]students.itb.ac.id

Abstract
Indonesia is a region that is directly adjacent to the Pacific Ocean and the Indian Ocean which allows a thermal front phenomenon. The purpose of this study is to identify the presence of thermal fronts based on seasonal variations and inter-annual variations in Indonesia. The data are Sea Surface Temperature (SST), Ocean Nino Index (ONI), and Dipole Mode Index (DMI) with a span of time from January 2007 - December 2017 (11 years). The SST data is a level 3 Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) satellite image data with a resolution of 4 km. SST data processing uses remote sensing techniques and Geographic Information System (GIS). The results of this study indicate that the distribution of SST and thermal fronts are influenced by seasonal variations and inter-annual variations. The highest average thermal front event in Indonesian waters occurred in a combination of El-Nino and Positive IOD conditions. The highest average thermal front incidence in Indonesian waters also occurred during the East Season, while the smallest average occurred during the Transition Season II. During West Season, Transition Season II, and East Season, the largest number of thermal fronts was found in Western Indonesian Waters. Meanwhile, in the Transition Season I, the largest number of thermal fronts was found in Central Indonesian Waters.

Keywords
thermal front, SST, remote sensing, seasonal and inter-annual variations

Topic
Marine Geodesy and Satellite Oceanography

Link: https://ifory.id/abstract/XJbgxF2hDPdY

Corresponding Author
Erlin Beliyana

Institutions
a) Oceanography Student, Bandung Institute of Technology Jalan Ganesha 10, Bandung 40132, Indonesia
Graduate Program in Earth Science, Bandung Institute of Technology Jalan Ganeca 10, Bandung 40132, Indonesia
b) Oceanography Research Group, Faculty of Earth Science and Technology, Bandung Institute of Technology Jalan Ganesha 10, Bandung 40132, Indonesia
c) Department of Atmospheric and Ocean, University of Maryland, USA

Abstract
Indonesian seas are strongly affected by strong semidiurnal tidal signals from the Indian Ocean and diurnal signals from the Pacific Ocean. Therefore, within the internal seas, there is possibility of mixed tides (semidiurnal and diurnal signals). This research is focused on determining tidal current based on the velocity data measured during the INSTANT (International Nusantara Stratification and Transport) program. The velocity data from Ombai Strait and Timor Passage from January 18, 2004 to December 31, 2004 are analyzed. Characteristics of tidal current data at certain fixed depths (50, 100, 350 and 750 meters) are processed and calculated using MATLAB software and present the magnitude and variability of total currents, residual currents, and tidal currents as well as vertical variability at these straits. In Ombai Strait and Timor Passage currents tend to move zonally (east – west). The dominant tidal currents are observed at 350 and 750 meters, while subtidal (nontidal) current dominant occurs with 50 to 150 meters.

Keywords
Currents; Tidal Currents; Residual Currents; Ombai Strait; Timor Passage

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/DWv7AbxjE39J

Corresponding Author
NUR SYAHIRAH HASHIM

Institutions
¹ Centre of Studies for Surveying Science and Geomatics, UiTM Shah Alam, Malaysia
² Geodesy and Geomatics Engineering Study Program, Faculty of Earth Science and Technology, Institute Technology of Bandung, Indonesia

Abstract
A hydrographic survey can be a cumbersome sometimes. The data can be sparse, providing it can be costly and it took a lot of manpower and time. Space-borne data like multispectral images can be a helpful tool towards hydrographic survey, especially in the shallow water area. The company like EOMAP and TCARTA make use of satellite-derived bathymetry as a tool and product. Would it be great if it also can be applied in Malaysia especially on the low-risk job or survey planning. Enlarging the survey area and providing a continuous and detailed water depth information is the main objective in this research. In order to complement with convenience and cost reduction, the author used Landsat 8 "(free downloadable images)" in this research. Structuring the procedure is the main part of the process involving pre-processing and processing step until the final product obtained. In this research, the author used various kind of bathymetry algorithms such as Single-Band Algorithm, Green-Band Algorithm, and Stumpf, and the author also uses Principal Component Analysis tool from ArcMap and Spear Relative Water Depth: Log-Ratio Transform tool from ENVI to derived bathymetry. All of this bathymetry algorithm/tool gives out different technique with different statistical approach. The final result then will be compared and evaluated with Single-Beam Echosounder data (ground truth).

Keywords
Hydrography Survey, Shallow Water Area, Satellite-Derived Bathymetry, Bathymetry Mapping

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/T6E2jndpxkfJ

Corresponding Author
Wingking Era Rintaka Siwi

Institutions
Institute for Marine Research and Observation, Ministry Marine Affair and Fisheries

Abstract
Bali strait get the influence of upwelling from the Indian ocean, especially when southeast monsoon (SEM). In normal years, upwelling processes in southern Java include Bali Strait appear when entering SEM in early June to mid-October, with cold SST. Climatic variability, the incidence of India Ocean dipole (IOD) is independent of ENSO. IOD correlates strongly with seasonal conditions. Medden Julian Ossilation (MJO) can affect the ENSO cyrcle even though it is not in the context of the cause Niño or La Niña formation, but can contribute to the speed of development and intensity of El Nino and La Niña. This study aims to investigate of ENSO, IOD and MJO toward the vertical temperature in Bali Strait during SEM (August 2013 & August 2017). The location of the study in Bali Strait 8.20S - 8.80S and 114.40E-115.20E. The method used is observation in August 2013 and 2017. The information about ENSO, this study is complemented by the Ocean Nino Index (ONI) climate index data and MJO obtained from NOAAs Climate Prediction Center. The information on IOD events is positive or negative mode, DMI data is also used from JAMSTEC. Information on the incidence of ENSO and IOD was used to further analyze the influence of these climatic conditions on the evolution of vertical temperature profiles in the Bali Strait. Seasonal vertical profile temperature variability linked to climate index in Bali Strait waters is processed and analyzed using ferret software from PMEL-NOAA, ODV, and General Mapping Tools (GMT). Based on the results vertical temperature in the August 2013 were relatively cooler with a thicker mixer layer than the August 2017. In the period of August 2013, the normal ENSO conditions (-0.3) with IOD (+) (0.1) with weakening intensity, while there was a period of August 2017 normal ENSO conditions (-0.16) with strong (+) IOD (0.6). Direct linier correlation among ENSO and IOD. MJO in August 2017 looks strong than August 2013 although at the same ENSO phase (neutral). Indirect linier correlation among ENSO and MJO.

Keywords
vertival temperature, ENSO, IOD, MJO, Bali Strait

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/uWN4KBjyMqpQ

Corresponding Author
Faruq Khadami

Institutions
1 Institute of Marine Geology and Resources, Department of Marine Sciences, Ocean College, Zhejiang University, Zhejiang University, Zhoushan 316021, China. gangli[at]zju.edu.cn
2 Institute of Geophysics and Geomatics, China University of Geosciences,Wuhan 430074, China

Abstract
We present a novel alternating joint inversion algorithm for controlled-source electromagnetic (CSEM) and seismic data. The two different physical parameters, i.e., the electromagnetic (EM) resistivity and seismic velocity, are correlated using the structural constraint during the inversion. The structural coupling used is the joint total variation (JTV) constraint, which is incorporated into the objective function of the individual EM or seismic inversion to enforce the structural similarity between the resistivity and velocity. The conventional cross-gradient constraint is not preferred as it can only be used for enforcing structural similarity for 2-D or 3-D case since it is always zero for 1-D joint inversion. The JTV constraint can be applied for 1-D joint inversion, as well as for the 2-D/3-D case, which is of a broader interest. The improved Gauss–Newton (GN) is used for minimizing the objective function and for reconstructing the subsurface resistivity and velocity. The alternating joint inversion algorithm is applied for integrating the CSEM data with cross-well seismic data for subsurface reservoir evaluation and water–oil identification. Numerical examples show that the developed joint inversion can improve the inversion results significantly over those from the separate EM or seismic inversion.

Keywords
Electromagnetics (EM), seismics, one dimension (1D), joint inversion, joint total variation (JTV), structural constraint.

Topic
Ocean Engineering and Technology

Link: https://ifory.id/abstract/PGuzTXwgYQ87

Corresponding Author
LH Wiryanto

Institutions
Department of Mathematics, Bandung Institute of Technology

Abstract
Two-fluid system of finite depth is considered in this talk. The fluids have different density and the height is also possible different. The interface between them is presented as the lower fluid height measured from the bottom. Because of a disturbance, that height changes at any time and position, so that it presents interfacial wave with KdV equation as the model. The wave propagation and deformation are observed for same various values of the physical parameters, such as density and height of the fluids. A finite difference method is shown successfully in performing the wave propagation. When the density and the height of the upper fluid tend to zero, the result confirms to the surface wave.

Keywords
KdV equation, interfacial wave, finite difference method

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/MZpUzHrj9aFu

Corresponding Author
Juventus W.R Ginting

Institutions
Experimental Station for Coastal Engineering Ministry of Public Work and Housing

Abstract
Hydraulic Test has been performed by Experimental Station for Coastal Engineering Ministry of Public Works and Housing to analyze the scouring pattern of Revetmen Sistem Panel Serbaguna (SPS) or Schematic Precast System (SPS) Revetment. There are 14 scenarios of experiment with different value of wave steepness and water depth. Scouring data is acquire through video recording which is later analyzed by image processing. In general, relative maximum scouring (Smax) and is about 0.6 of its significant wave height (Hsig). This is also the case for relative toe scouring (Stoe). For various wave steepness, Smax is no more than 0.31 of its toe depth (ht) whereas maximum scouring distance from its toe (Xmax) is no more 0.14 of the wavelength.

Keywords
, maximum scouring, maximum scouring distance, toe depth, image processing

Topic
Ocean Engineering and Technology

Link: https://ifory.id/abstract/CT9GtFxfgaUw

Corresponding Author
Syafyudin Yusuf

Institutions
a,b Marine Science, Hasanuddin University
c Graduate School of Hasanuddin University
d Bogor Agriculture University

Abstract
Land clearing for mining operations is rampant around Sulawesi. This land opening increases the sedimentation load and eutrophication of the waters so that it disturbs life in the coral reef ecosystem on the coast. The threat of coral death originating from the overflow of sediments that enter the ocean waters is presumed to occur at the coast of the Bone Bay. This study aims to identify indicators of damage to coral reefs around the land mining area of the Northern Bone Bay. Observations of the substrate cover of coral reef ecosystems were carried out in 2015, 2016 and 2017 using a UPT (Underwater Photo Transect) method along 50 meters at a depth of 2 and 6 meters. The ecological impact indicators such as eutrophication and sedimentation used in this study are macro algae cover, dead coral with algae, silt, water clarity, total suspended solid (TSS) and sedimentation rate. The results show that there have been significant changes in live coral cover and other substrates during the study period. Scleractinian coral cover decreased, while dead coral with alga, macro algae, soft corals and sponges cover increased. The cause of coral death is not only by sedimentation and eutrophication, but also due to the occurrence of bleaching in 2016. Very few indications of new destruction due to destructive fishing. High turbidity and TSS concentration observed in this study were caused by sediment supply from the Malili river which is estimated due to mining and land clearing in the surrounding mountains.

Keywords
Coral Reef Degradation, Land Mining, River Overflow, Low seawater quality, Land Mining, Bone Bay Indonesia

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/j89hDLBfvRgH

Corresponding Author
Kosasih Prijatna

Institutions
Geodesy Research Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung

Abstract
Sea level spatio temporal variability in Indonesian waters is an important oceanographic aspect to be investigated. This is related to the use of satellite altimetry data in physical geodesy studies in the region. Due to its location at the equatorial zone and as an archipelagic region, Indonesian waters should experience complex behavior and pattern in term of sea level. Identification and analysis of those phenomena require precise sea level observation over a long period of observation. Topex, Jason 1, Jason 2, and Jason 3 satellite altimetry missions have been observing sea level for more than two decades. In this research, the use of these altimetry data from 1992 to 2019 in identifying and analyzing the long term sea level variability in Indonesian waters will be investigated.

Keywords
satellite altimetry; sea level variability; Indonesian waters

Topic
Marine Geodesy and Satellite Oceanography

Link: https://ifory.id/abstract/4CE6QKBhzvjd

Corresponding Author
Engki A Kisnarti

Institutions
(1)Study Program of Earth Sciences, Faculty of Earth Sciences and Technology, Institute Technology of Bandung, Indonesia (email: engki224[at]students.itb.ac.id)
(2)Study Program of Oceanography, Faculty of Engineering and Marine Sciences, University of Hang Tuah Surabaya, Indonesia
(3)Director of Marine Science and Technology, Coordinating Ministry for Maritime Affairs Republic of Indonesia
(4)Science Programs Director, 5 Gyres

Abstract
Recent publications state that some researchers found microplastic marine debris were spread in all waters around the world, including in Indonesia. These microplastic marine debris can be found near the sources of garbage or spread to waters near remote islands, in the form of fragments or fibers. The 5 Gyres Expedition 2018, using KLM Sea Safari VII, sailed along the waters of Nusa Tenggara, Indonesia on July 21st-29th, 2018. One of the objectives of this expedition was to collect data on the abundance of microplastic marine debris (size < 5 mm) from the waters of Labuan Bajo to Lombok, which has not been recorded until now. Seawater samples were taken on the surface and analysed for the shape and total concentration of microplastic (microplastic particles/liter). The result, microplastic found in all samples of seawater in the form of fibers and fragments. The fibers from were found in all sampling locations (12 locations), while in fragments from were only found in 6 locations. Near Labuan Bajo-East Nusa Tenggara, microplastic in the form of fibers as much as 10 particles/liter were mostly found. Meanwhile, 27 particles/liter in the form of fragments were found mostly in the waters near Gili Banta Island - West Nusa Tenggara (uninhabited island). During the cruise, ocean currents move from east to west with a maximum speed of 0.6 m/s in the northern part of Nusa Tenggara. These ocean currents partially move southward through the Sape Strait with a maximum speed of 1.45 m/s. It is estimated that marine microplastic debris from Labuan Bajo (east of the Strait of Sape) and Sangeang Island (west of the Strait of Sape) are concentrated on Gili Banta Island due to ocean currents. Results of this expedition reinforce previous findings that microplastic can be found in almost sea areas around the world, not only in densely populated areas but also in remote places that far away from the garbage sources. The contribution of ocean currents seemly very significant on transporting the marine microplastic debris.

Keywords
marine microplastic debris, Nusa Tenggara, 5 Gyres Expedition

Topic
Marine Resources, Conversation and ICZM

Link: https://ifory.id/abstract/HKDkWetArZjb

Corresponding Author
Corry Yanti Manullang

Institutions
1. Center for Deep Sea Research - Indonesian Institute of Sciences

2 & 3 : Research Center for Oceanography, Indonesian Institute of Sciences

Abstract
Since late 2011 mercury has been used to extract the gold requiring in artisanal gold mining in Mt. Botak (Buru Island) and resulting in deposition of mercury into Kayeli Bay. In this project we reported the updated total mercury (THg) concentration in marine sediment and nine spesies of domersal fish from Kayeli Bay. Nine coastal sampling sites were selected in the Kayeli Bay by purposive sampling. The fish are collected from traditional market in Buru Island. The total mercury (THg) concrentrations in marine sediment were found in all sites, ranged from (in mg/kg, dry weight): 0.035 to 4.802. The THg concentrations in sediments from all sites measured were found has exceeded the National Oceanic and Atmospheric Administration (NOAA) value. Among fish, the highest THg concentration of 1.667 mg/kg DW was measured in the muscle species Myripristis kuntee and the lowest THg concentration detected for Lutjanus Lutjanus (0.016mg/kg dw). The distribution of total mercury (THg) concentrations found in marine sediment of Kayeli Bay shows a very closed relationship to the artisanal gold mining activity in Mt Botak..

Keywords
Mercury, artisanal gold mining, marine sediment, fish, Kayeli Bay

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/dgeHJD9YbNwR

Corresponding Author
Rahmat Sawalman

Institutions
a) Department of Marine Science, Faculty of Marine Science and Fisheries, Universitas Hasanuddin, Makassar, Indonesia.
*rahmatsawalman24[at]gmail.com

Abstract
The occurrence of marine debris on seagrass beds will be through fragmentation into small particles called microplastics (MPs). Sea urchins (Echinoidea) is one of the associated organisms on seagrass beds which can accumulate microplastics by mode of its feeding habits. This research was conducted from October-December 2018 in Barranglompo Island and aimed to know the abundance and characteristics of microplastics that accumulates in sea urchins (Tripneustes gratilla), seagrass leaf, and sediment. Sampling location was conducted at the area where T. gratilla were found. A sampling of sea urchins was taken in multispecies seagrass (Enhalus acoroides and Thalassia hemprichii). MPs in sea urchins, seagrass leaf and sediment were identified by visual identification method using a stereo microscope. The results showed that all samples of sea urchins (n=10), seagrass leaf (n=24), and sediment (n=8) were 100% contaminated by MPs. The average abundance of microplastics in sea urchins T. gratilla was 27.60±5.31 MPs/individual; in seagrass leaf E. acoroides and T. hemprichii in the T. gratilla sampling area were 0.15±0.03 MPs/cm2 dan 0.23±0.04 MPs/cm2, respectively; in sediment of T. gratilla sampling area was 152.50±29.38 MPs/kg. The characteristics of MPs were found to show similarities such as color (dominated by blue) and form (dominated by line).

Keywords
Microplastic; Sea urchin; Seagrass; Spermonde; Indonesia

Topic
Marine Resources, Conversation and ICZM

Link: https://ifory.id/abstract/hYKEvb2C9n7d

Corresponding Author
Fareza Sasongko Yuwono

Institutions
a) Research Center for Deep Sea, Indonesian Institute of Sciences
Jalan Y. Syaranamual, Guru-Guru, Poka, Ambon 97233, Indonesia
*fare001[at]lipi.go.id
b) Faculty of International Resource Sciences, Akita University
1-1 Tegatagakuen-machi, Akita 010-8502, Japan

Abstract
Calcareous nannofossil records in the sediments from ODP Hole 806B located in Ontong Java Plateau comprising Reticulofenestra size variations, Discoaster relative abundance and nannofossil accumulation rates have been analyzed to reconstruct surface water dynamics in the western equatorial Pacific throughout the Miocene. From early to middle Miocene (18 – 14.4 Ma), the surface water was relatively warm and depleted in nutrient associated with warm condition during the Middle Miocene climatic optimum. From middle to late Miocene (14.4 – 8.8 Ma), the thermocline deepened as the western Pacific warm pool established. During the late Miocene (8.8 – 5.6 Ma), the surface water suddenly shifted into cooler and nutrient rich condition associated with enhanced equatorial upwelling. The timing of this event is coincided with the intensification of Asian monsoon.

Keywords
Miocene, sea surface, Western Equatorial Pacific, Calcareous Nannofossil

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/DrHdYaEZhMjz

Corresponding Author
Munawir Bintang Pratama

Institutions
Department of Ocean Engineering
Institut Teknologi Bandung, Bandung 40132, Indonesia
munawirbintang[at]gmail.com

Abstract
Tidal flood has been an inevitable coastal hazard for some water-front cities in Indonesia, especially in Java Island. Besides Jakarta – the Capital City, Pekalongan City in the North Coast of Central Java is one of the cities suffered. This paper aims to study the effectiveness of coastal dyke in reducing inundation in Pekalongan City using a numerical hydrodynamic model. The model is performed using Delft-3D equipped with spatial data provided by The Indonesian Agency for Geospatial Information. The model is validated against the observed tidal elevation and shows a good agreement. In the validated model, land subsidence and sea level rise are applied. Also, three scenarios of dyke elevation are studied and simulated in 2020, 2030, and 2050. The results presented are the maximum flood depth and the area inundated per scenario.

Keywords
Tidal flood; Coastal hazard; Coastal dyke; Pekalongan

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/Rkat9rfJDHqc

Corresponding Author
Ramzi Bamahry

Institutions
(a) Department of Ocean Engineering, Institut Teknologi Sepuluh Nopember Surabaya, Kampus ITS, Sukolilo, Surabayan 60116, Indonesia

Abstract
In Indonesia, one of the regions that has good potential for Floating Offshore Wind Turbine (FOWT) installations is the Natuna Sea which has a fairly good average wind speed in the range of 7.0 - 11.0 m/s. In addition, the Natuna Sea has water depth of around 80-250 m with relatively mild wave height. This condition is a suitable environment for the installation of the FOWT. Therefore, it is necessary to investigate the appropriate mooring system configuration due to the motion of the structure. This paper examined the analysis of mooring system of the SPAR type FOWT structure due to its global motion through numerical modeling by using open source software FAST. The Spar structure was successful applied in the offshore oil and gas industries which has a special feature of deep-draft so that its motion characteristics are very good/stable because the Spar is not too affected by wind, waves or ocean currents, compared to other floating structure types. The Spar use is even capable of up to a depth of 10,000 ft (= 3,048 m). The analysis was carried out for operation condition, by varying three configurations of the mooring system for direction of environmental loads (waves and winds), namely 0 degree (perpendicular in front of the turbine), 45 degrees, and 90 degrees (the turbine side direction) and wind speed. With the scope of such analysis, it could be properly examined the mooring system due to global motion of heave, roll and pitch of the Spar. This situation will prevent the Spar to structurally collapse and in turn its motion will not decrease the efficiency of the wind turbine itself.

Keywords
Spar Offshore Wind Turbine; Mooring analysis; Heave; Roll; and Pitch motions.

Topic
Ocean Engineering and Technology

Link: https://ifory.id/abstract/e6AYwQpzWjqr

Corresponding Author
Muhammad Masrur Islami

Institutions
Center fo Deep Sea Research, Indonesian Institute of Sciences – LIPI
Jl. Y. Syaranamual, Poka, Ambon, Maluku, Indonesia – 97233
* Email: muha067[at]lipi.go.id

Abstract
Tylothais aculeata is one of the gastropod species member of the family Muricidae, order Neogastropoda. This species plays an important role in the marine macrobenthic community. This study aims to determine the variations and relationships of shell dimension i.e. shell length (SL), shell width (SW), shell height (SH) of T. aculeata associated with the hard substrates in Ambon Island, Maluku. Field sampling was conducted in eight locations, in August 2016, with purposive sampling method in typical hard substrates of chosen coastal areas. A total of 751 individuals were found and divided to sixteen size ranges with three peaks of its size group. The highest and the lowest number of individual was found in Dok Talake (DT) and Gudang Arang (GA), respectively. The highest frequency was 96 individuals on range of 28-30 mm, while the lowest one was only 4 individual on range of 42-44 mm. The characteristics of shell dimension relationship of SL-SW and SL-SH were positive allometry; SW-SH was negative allometry; and SL-TW was positive allometric, respectively.

Keywords
Muricid Tylothais aculeata, morphometrics, hard substrates, Ambon Island

Topic
Marine Resources, Conversation and ICZM

Link: https://ifory.id/abstract/dRMYXZpNTf6U

Corresponding Author
FADEL RAHMAT RAMADHAN

Institutions
a) Departement of Ocean Engeering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia

Abstract
In Indonesia, one of the regions that has good potential for Floating Offshore Wind Turbine (FOWT) installations is the Natuna Sea which has a fairly good average wind speed in the range of 7.0 - 11.0 m/s. In addition, the Natuna Sea has water depth of around 80-100 m with relatively mild wave height. This condition is a suitable environment for the installation of the FOWT. This paper examined the analysis of the global motion of SPAR type FOWT structure and its mooring system through numerical modeling by using open source software FAST. The Spar structure was successful applied in the offshore oil and gas industries which has a special feature of deep-draft so that its motion characteristics are very good/stable because the Spar is not too affected by wind, waves or ocean currents, compared to other floating structure types. The Spar use is even capable of up to a depth of 10,000 ft (= 3,048 m). The analysis was carried out for parking condition, as a basic condition, by varying the direction of environmental loads (waves and winds), namely 0 degree (perpendicular in front of the turbine), 45 degrees, and 90 degrees (the turbine side direction) and wind speed. With the scope of such analysis, it could be properly examined the global motion modes (heave, roll and pitch) at suitable mooring system. This situation will prevent the Spar to structurally collapse and in turn its motion will not decrease the efficiency of the wind turbine itself.

Keywords
Floating Offshore Wind Turbine; Motion Analysis; Spar Type; Natuna Sea

Topic
Ocean Engineering and Technology

Link: https://ifory.id/abstract/WcR3QAUX8tgJ

Corresponding Author
Didit Adytia

Institutions
a*) School of Computing, Telkom University, Bandung, 40257, Indonesia
*adytia[at]telkomuniversity.ac.id

&

b) Industrial & Financial Mathematics Research Group,
Faculty of Mathematics & Natural Sciences,
Institut Teknologi Bandung, Bandung, 40132, Indonesia

Abstract
Modelling of wave transformation above fringing reefs are usually quite challenging. The fringing reefs are usually characterized by very steep bottom slope, so that waves that propagate above this type of bottom are usually break. To simulate the wave propagation above fringing reefs, the wave model and its numerical implementation should able to describe shoaling, breaking, nonlinear wave-wave interactions as well as dispersion accurately. In this paper, we use a Boussinesq type of model to simulate the wave transformation above fringing reefs. The wave model is implemented numerically by using finite volume method with momentum conservative staggered grid. The model is called Staggered grid Variational Boussinesq (SVB). Results of numerical implementation is validated with experimental data from hydrodynamic laboratory. Various scenarios are investigated to study effects of fringing reefs in reducing wave height.

Keywords
fringing reefs; Staggered grid Variational boussinesq model; Finite Volume.

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/pYbjtf4KAH6L

Corresponding Author
Ashadi Arifin Nur

Institutions
a) Faculty of Earth Science and Technology, Bandung Institute of Technology
Jalan Ganesa No 10, Bandung, 40132, Indonesia
*ashadi_arifin_nur[at]students.itb.ac.id
b)Hydro-Atmosphere Environment Research Group, Physical Oceanography and
Computational Modeling Laboratory, Program Study of Physics,
Faculty of Mathematics and Natural Sciences, Mulawarman University
Jalan Barong Tongkok No 04, Samarinda, 75123, Indonesia

Abstract
The coastal area in Balikpapan Bay and its surrounding area has been devastated after the burst of an underwater oil pipe at the bay on March 31st, 2018, and the crude oil still continues spreading for a few days later. A three-dimensional hydrodynamic model is used to simulate the currents dynamic and investigate the influence of the currents circulation on the spreading of the oil spill in Balikpapan Bay from March 31th to April 15th, 2018, to cover the event i.e. several weeks after the oil spill incident. Model results are validated by calculating the RMSE, MAPE and model skill using water level between available observation data at Semayang Port, Balikpapan station and numerical model from October 1st, 2012 to January 1st, 2013. Verification result of tidal elevation data from observation and model prediction shows a good agreement with RMSE = 7.8 cm, MAPE = 14.3% and model skill = 0.995. Surface currents circulation in Balikpapan Bay can be distinguished by the currents pattern on the spring tide and neap tide condition. During the spring tide condition, the surface currents mostly move to the east after coming out from the bay. However, the surface currents are strongly going southward after come out from the bay on the neap tide condition. Based on the satellite images captured for the next days after the event, the spreading pattern of the oil spill seems to be matched to the pattern of surface currents circulation on the spring tide condition. From the analysis of the model result, it shows that the currents circulation playing the main role to disperse the oil spill in Balikpapan Bay towards the Makassar Strait.

Keywords
Tidal current; Hydrodynamic model; Balikpapan Bay; Oil spill

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/LbzNAFEYuCwW

Corresponding Author
Faruq Khadami

Institutions
1 Ocean College, Zhejiang University, Zhoushan, 316021, China;
Correspondence to: Weijie Liu (weijieliu[at]zju.edu.cn)

Abstract
The extents of wave-driven flooding along the coastline fronted by fringing reefs during severe weather depend on the state of the reef. It is believed climate change will result in a net increase in the water depth over the reef flat, a degrading of the surface roughness of coral reefs and changes in extreme incident wave heights. For a better understanding of the impact of climate change on wave-driven flooding hazards over reef-fringed coasts, this study utilized a Boussinesq wave model, FUNWAVE-TVD, to simulate irregular wave transformation and run-up over fringing reefs. Validated with experimental data, the present model shows reasonable prediction of irregular wave evolution and run-up height. Numerical experiments were then implemented based on the anticipated effects of climate change and carried out to investigate the effects of sea level rise, degrading of the reef surface roughness and increase of extreme incident wave height on the irregular wave run-up height over the back-reef beach. Variations of spectral components (i.e., significant sea-swell run-up height, infragravity run-up height and 2% highest run-up height) of irregular wave run-ups were examined and discussed to better understand the underlying physical process.

Keywords
fringing reefs; irregular waves; run-up; climate change; spectral components

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/Tn37xvtNc49k

Corresponding Author
Dhimaz Galih Prasetyo

Institutions
a) Research Center for Deep Sea, Indonesian Institute of Sciences
Jl. Y. Syaranamual, Ambon 97233, Indonesia
*dhim001[at]lipi.go.id

b) Oceanography Research Group, Faculty of Earth Science and Technology
Bandung Institute of Technology, Jl. Ganesha No. 10, Bandung 40132, Indonesia

Abstract
Northern Ambon Area has a unique characteristic in term of biodiversity, including Macroalgae and Echinodermata. This research aims to determine the distribution of nutrients in the territorial waters of North Ambon in 2017 and 2018 and their effects on the distribution of Macroalgae and Echinodermata. Seawater samples were obtained in 26 sampling points in 2017 and 18 sampling points in 2018 located in Northern Ambon coastal area. The determination of chemical parameters are using a Spectrophotometric Method consisting of NO3, PO4, and SiO2 concentration determination, as well as determining pH and DO using a pH meter from seawater samples taken. The results of the analysis show that the average concentrations of NO3, PO4, and SiO2 in the study area in 2017 were 0.090 mg/L; 0.042 mg/L; and 0.330 mg/L with an average DO and pH content of 5.83 mg/L and 8.19. Meanwhile, the average concentrations of NO3, PO4, and SiO2 in the sampling area in 2018 were 0.028 mg/L; 0.021 mg/L; and 0.129 mg/L with an average DO content and pH of 7.54 mg/L and 7.64 mg/L. Based on the 2004 Decree of the State Minister of the Environment, No. 51 about Sea Water Quality Standards for Marine Biota, it is known that the concentration of NO3 and PO4 in the Northern Ambon coastal area exceeds the maximum threshold that has been determined, but still indicate the suitability intended for the life of the biota. The values of NO3 and PO4 concentrations in 2017 and 2018 also indicate that the trophic status of the seawater is between Oligothropic and Mesotrophic. There is a decrease in the concentration of whole nutrients from 2017 to 2018 which influences the variability of macroalgae and Echinodermata observed in the study area in 2018 when compared to 2017. The Macroalgae classes that can be found in this area are Rhodophyceae, Phaeophyceae, and Chlorophyceae. Furthermore, the Echinodermata classes found in this area are Holothuroidea, Ophiuroidea, Asteroidea and Echinoidea.

Keywords
Ambon Area, Echinodermata, Macroalgae, Nutrient

Topic
Marine Resources, Conversation and ICZM

Link: https://ifory.id/abstract/EHMukYg3Aja8

Corresponding Author
Sam Wouthuyzen

Institutions
a) Research Centre for Oceanography – Indonesian Institute of Sciences. Jl. Pasir Putih 1, Ancol Timur, Jakarta 14430, Indonesia.
b) Centre for Deep Sea Research – Indonesian Institute of Sciences. Jl. Y. Syaranamual, Poka, Ambon 97233 – Indonesia
c) Centre for Hydrography and Oceanography – Indonesian Navy, Jakarta, Indonesia.
d) Departement of Remote Sensing Technology, Indonesian Defence University, Bogor, Indonesia
e) Graduate Research School, College of Science and Engineering, James Cook University, Australia
f) Centre of Excellence for Tuna Conservation – Ambon, Jl. Y. Syaranamual, Poka, Ambon 97233 – Indonesia

Abstract
Salinity is an important conservative tracer in the ocean considered as a proxy to explain physical and chemical processes in the system (e.g. upwelling process and nutrient flux) controlling biological activities (e.g. primary production). Combining with temperature and chlorophyll-a (Chl-a), these three oceanographic parameters are important to reveal the water quality of a marine system supporting fishery. In a significantly large spatial scale system of ocean processes such as upwelling systems, the availability of spatial and temporal sea surface salinity (SSS), sea surface temperature (SST) and Chl-a data is essential to be used for this water quality purpose and is mostly sourced from remote sensing-based measurements. However, the satellite-derived SSS dataset (~4 to 9 years long) is not as temporally adequate as SST and Chl-a datasets (~3 decades long) thus, preventing a comprehensively spatio-temporal analysis of this water quality aspect. Since SSS can be approximated using satellite-derived ocean color products having the similar temporal length of datasets to the available SST and Chl-a datasets, predicted SSS can be produced from these ocean color products to fill the gap of the existing SSS dataset. Here, we estimated SSS from ocean color products of Aqua-MODIS satellite with a spatial resolution of 4 km by developing an empirical model. Ocean products used in this study were remote sensing reflectances (Rrs) at a range of blue (412, 433, 469 and 488 nm), green (531, 547 and 555 nm) and red wavelength (645, 667 and 678 nm). We also used absorption coefficients due to detritus material non-algae, Gelbstof and CDOM (ADG) at 443 nm and the absorption coefficient due to phytoplankton (APH) at 443 nm. We chose Banda Sea as our area of interest due to its large-scale upwelling system (~300 km x 300 km) providing an important ocean process related to fishery and the availability of in-situ salinity measurements in this location (i.e. CTD casts from series of R/V Baruna Jaya III, VII and VIII cruises and Argo floats), which a part of these datasets will be used to validate our empirical SSS model. As results, we found that ADG-using empirical model (polynomial regression order 5) produces the highest correlation to SSS with R2 of 0.940. The average of all Blue and Green Bands ratio of B/G (R2: 0.903), Blue Chromaticity [B/(B+G+R)] (R2: 0.917) and Green chromaticity [(G/(B+G+R)] (R2: 0.836) also show the similar result, while the rest ocean color products in our empirical model only produce weak correlation to SSS (R2<0.7). Due to its accuracy, ADG was selected as empirical model to estimate SSS. The root mean square error (RMSE) of this model was significantly small (0.130 psu). The predicted SSS using ADG is well validated to Argo floats (RMSE < 0.3 psu) and Aquarius satellite measuring SSS (RMSE: 0.15 psu). The accuracy of ADG-derived salinity at 443 nm indicates that this approach can be used to investigate upwelling process in

Keywords
Sea Surface Salinity, Ocean Color, empirical model, Banda Sea

Topic
Marine Geodesy and Satellite Oceanography

Link: https://ifory.id/abstract/Qpxy2NELuVMd

Corresponding Author
Aswan Aswan

Institutions
Geology Department, Institut Teknologi Bandung (ITB), Jl. Ganesha 10 Bandung, Indonesia (40132); email: aswan_gl[at]gc.itb.ac.id, +62-85314001580

Abstract
Several major tsunami events in Indonesia, such as in Aceh, Pangandaran, Palu and Banten areas, have raised our awareness of the importance of paleotsunami deposits study, especially in relation to the determination of their occurrence time intervals. The Palu and Banten tsunami events have given new perception to the community that tsunami waves can be caused not only by earthquakes but also by landslides (or underwater landslides). One of the problems faced in paleotsunami deposits study is that their sediment show some similarities to those of storm deposits. Another problem is to determine whether the deposits are related to earthquake-induced or landslide-induced tsunamis; hence, it is important to study their characteristics, respectively. Age of tsunami-derived material sedimentation is critical for estimation of tsunami event time intervals in a particular region. Several alternative age determination methods will be discussed in this study, taking into account the estimated age of the tsunami deposits.

Keywords
paleotsunami, deposit, storm, landslides, age

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/nhHk4URgEpvN

Corresponding Author
karina aprilia sujatmiko

Institutions
a) Program Study of Oceanography, Bandung Institute of Technology, Labtek XI, Jl. Ganesha no.10. Bandung, Indonesia.
b) Center for Marine and Coastal Development, Institut Teknologi Bandung, Labtek XI, Jl. Ganesha no.10. Bandung, Indonesia
*karina.sujatmiko[at]oceanography.itb.ac.id

Abstract
West Java coastal areas are endangered by the slow-onset of global sea level rise and the increasing frequency of coastal hazard such as storm surge and coastal flood due to climate change. Located near the subduction zone of Eurasia and Indo-Australia plate, West Java also faced rapid onset disaster such as tsunami especially in the southern coast. Physical vulnerability has implications for socio-economic, infrastructure, and ecosystem conditions of the coastal zones. Therefore, it is substantial to conduct a coastal vulnerability assessment and provide a relevant GIS map. This assessment strengthened by extensive surveys along the coast of West Java and interviews with the local communities. This study discussed potential inundation hazard in the future caused by climate induced hazard in regard with oceanographic parameters such as ENSO, MJO and IOD and local tidal height. Based on recording data and projection it is found that the contribution of La Niña variation as much as 21.7 cm, MJO 24.3 cm, Indian Ocean Dipole mode 16 cm, maximum tidal height is 95.77 cm, global sea level rise projection 0.7 cm/year and increased storm surge up to 150 cm. Using tsunami model for the 100-year return period, the expected tsunami height ranges from 2 to 7 m. A hazard map is developed using a simple analytical model representing occurrence of cumulative hazards of flooding or inundation that could occur in coastal areas according to a scenario of condition. There are selected 10 hazard scenarios based on the combination of hazard elements developed for 2020 - 2050 projection. The extreme climate induced hazard inundation is gained when all parameters, except tsunami, are occurred in conjunction which resulted in extreme height of 334.5 cm in year 2050. While, the combination of climate and tectonic induced hazard inundation resulted in extreme height of 779,6 cm in year 2050. The detailed of inundation potential hazard is then presented into maps by using Geographic Information systems (GIS) and elevation model of Southern coast of West Java.

Keywords
Sea level rise, inundation hazard, tsunami

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/CXyjMeRcTFHA

Corresponding Author
Marsya Jaqualine Rugebregt

Institutions
Research Center of Oceanography - LIPI

Abstract
Abstract. Changes in pH, temperature, and salinity in seawater can indicate the occurrence of ocean acidification. This study aims to study changes in acidity that occur in Ohoililir waters, Southeast Maluku, which is part of the Banda Sea. This research was conducted in March 2019 as a study of the prefix of oceanic equities in the Southeast Maluku region which is part of the Banda Sea which is currently one of the priority researches in Indonesia, and sampling at 10 points associated with coral reefs and seagrass ecosystems. The results obtained were pH ranging from 8.567 – 8.851 with an average of 8.6879, temperatures ranged from 29.285 – 30.281oC with an average of 29,7412°C, and salinity ranged from 33.041-33.33 with an average of 33,2355. Its shows that pH, temperature, and salinity of Ohoililir waters are still a good range for the life of marine biota.The correlation between pH and temperature is -0.097 and the correlation between pH and salinity is in the range of -0.054 which indicates has no relationship between pH and temperature and salinity. Beside that, pH has negative correlation to temperature and salinity. This shows the need for further research on the relationship between these three or more parameters to see the effect on ocean acidification.

Keywords
pH, temperature, salinity, ocean acidification, Ohoililir

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/JTBMgxRNw6nj

Corresponding Author
Camellia Kusuma Tito

Institutions
Institute for Marine Research and Observation
Ministry of Marine Affairs and Fisheries
Jl. Baru Perancak, Jembrana, Bali, 82251, Indonesia

Abstract
Coral reefs facing climatic challenges due to increased carbon dioxide (CO2) concentration in the atmosphere, elevated sea surface temperatures (SST) and sea level anomaly (SLA). Recent works highlighted that El Niño-Southern Oscillation (ENSO) increases SST and induces bleaching events in several region. Meanwhile, SLA impacts on coral reefs have rarely been addressed but could be more important for reefflat ecosystem than previously thought. The objective of this work is to assess SLA impacts on Tomini-s reef coral bleaching stress. In 1998, 2010 and 2016 Tomini-s reef coral experienced severe bleaching period during hot spot (HS) occupied in a certain water body on certain time, called degree of heating weeks (DHW, 0C-week). Long term (1993-2019) SLA data acquired from multimission altimetry satellite by Copernicus Marine Environment Monitoring Service (CMEMS) were used in the analysis. The results show that the slope of SLA in Tomini Bay tend to increased for the last three decades. Therefore, we suggest that effects of combined rising SST and SLA could be increased Tomini-s reef coral bleaching stress.

Keywords
Bleaching, Coral reef, Sea level anomaly, Sea surface temperature

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/yNJ2496xHbFY

Corresponding Author
Riza Yuliratno Setiawan

Institutions
a) Department of Fisheries, Faculty of Agriculture, Universitas Gadjah Mada, Jl. Flora Gd. A4, Bulaksumur, Yogyakarta 55281, Indonesia
*riza.y.setiawan[at]ugm.ac.id
b) Department of Oceanography, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Soedarto, S.H., Tembalang, Semarang 50275, Indonesia
c) Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya. Jl. Palembang - Prabumulih, Km. 32, Inderalaya, OI, Sumatra Selatan, 30662, Indonesia

Abstract
Long-term satellite data (2003-2017) are analyzed to investigate the variability of ocean surface chlorophyll-a (Chl-a) concentration off the Halmahera Island under influence of the Indonesian Australian Monsoon and the El Niño-Southern Oscillation (ENSO). In this study, we first analyzed the seasonal variability of Chl-a, and then describe the relationship between sea surface Chl-a, sea surface temperature (SST), and sea surface wind stress in the region. Our results demonstrate that prevailing northerly and southeasterly wind stresses play a pivotal role in generating Chl-a maxima off the Halmahera Island. On seasonal time scale, the strengthening of northerly and southeasterly wind stresses (up to ~0.01 N m-2) during the Northwest and Southeast Monsoon seasons produce enhanced phytoplankton blooms associated with sea surface cooling (~28.8 °C) in the area of study. On interannual time scale, the largest positive Chl-a and wind stress anomalies and the coolest SST anomaly are observed in 2006 during El Niño event. Meanwhile, the greatest negative Chl-a anomaly is prevailed during the 2016 negative IOD event. This study demonstrates that wind variability is the essential factor in determining the magnitude of Chl-a maxima off the Halmahera Island.

Keywords
Chlorophyll-a; ENSO; Halmahera Island

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/u8QchJ6arb3Y

Corresponding Author
Wahyu Setyo Kuntoro

Institutions
1)Study Program of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology
2)Research Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology
*Corresponding author: nining[at]fitb.itb.ac.id

Abstract
Seasonal characteristics of wave height in Southern Bali waters in 2014 was simulated using SWAN (Simulating Wave Nearshore) model with the resolution of 1/216° (0.51 km). The model was forced using Cross Calibrated Multi Purposed (CCMP) wind data with resolution 1/4° (27.75 km) and 1/600° (0.18 km) bathymetry data derived from Batimetri Nasional (BATNAS) provided by Geospatial Information Agency (BIG). The result shows that the highest (lowest) seasonal average of Significant Wave Height (SWH) in Southern Bali waters (SBW) in 2014 during east (west) monsoon or JJA (DJF) on June-July-August (December-January-February) months was about 2.2 m (1.4 m). Meanwhile, SWH during the first (second) transitional monsoon or MAM (SON) on March-April-March (September-October-November) months was about 1.7 m (2.1 m). The 2D spectrum analysis exhibits that seasonal wave characteristic in Southern Bali waters (SBW) was dominated by swell propagation from the Indian Ocean (IO). Corresponding to the SWH, seasonal average of wave energy spectrum during east monsoon (JJA) shows that the highest value is up to 0.0038 m2s/deg compared to the other seasons.

Keywords
Wave height, SWAN (Simulating Wave Nearshore), Southern Bali, seasonal characteristics

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/XD4LAhQV9Czx

Corresponding Author
Hanif Santyabudhi Sutiyoso

Institutions
a) Study Program of Oceanography, Institut Teknologi Bandung, Indonesia
*santyabudhi[at]oceanography.itb.ac.id

b) National University of Ireland Galway, Ireland

Abstract
Rip currents are hydrodynamic events that vary alongshore and important to be well-understood for its uniqueness and safety issues on recreational beaches. In this study, bathymetrically-controlled rips are the main focus as this type is commonly found on Indonesia-s coastal areas, particularly in the south coast of West Java. This unique hydrodynamics feature affects sediment characteristic, particularly at the rip channel as the lower part tends to have coarser sediment due to larger friction. Such complex interactions need thorough investigation, therefore, a study was conducted in Pangandaran which well-known for its rip currents. Field observation was made to collect sediment sample on a cross-shore direction which shows finer sediment on upper rip channel and coarser sediment on the lower part with a diameter size of 0.35 mm and 0.37 mm, respectively. In addition, simple simulations were also made to illustrate rip current movement on a channel. The result shows that in the strongest current area with over than 3.0 m/s current speed, i.e. on the lower part of the rip channel, bed shear stress is found to be the strongest. It is been noticed as well that the bed shear stress forms a pattern which delineates overall movement of a rip current. Furthermore, the variation of bed shear stress is revealed as the main cause of sediment distribution along the cross-shore direction. Therefore, this simple approach qualitatively illustrates the dynamics of a rip current phenomenon.

Keywords
rip current, coastal morphology, sediment, Delft3D

Topic
Coastal and Ocean Dynamics

Link: https://ifory.id/abstract/nKE4vQRUukT2

Corresponding Author
Faruq Khadami

Institutions
1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China.
2. Institute of Marine Geology and Resources, Zhejiang University, Zhoushan 316021, China.
3. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
4. South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
* Corresponding author: Chun-Feng Li, cfli[at]zju.edu.cn

Abstract
In 2016, we carried out a coincidental multi-channel reflection seismic and wide-angle reflection/refraction seismic experiment along a 320-km long profile across the northeastern margin of the South China Sea (SCS). Based on these new data, we studied velocity structure of the transitional continental crust using both ray-tracing based seismic phase modeling and travel-time tomography. The velocity model shows that Mesozoic sediments have velocities of 4.3-5.3 km/s and are about 3-6 km thick in the magnetically quiet Chaoshan Depression and the attenuated transitional continental crust. This confirms that it is this thick layer of weakly magnetized Mesozoic sediments that causes the magnetic quiet zone. This Mesozoic layer pinches out seawards near the continent-ocean boundary. Two apparently isolated high-velocity anomalies are revealed in the lower crust of the continental slope. The first has velocities of 7.0-7.5 km/s and a maximum thickness of 8 km, and the second has velocities of 7.0-7.3 km/s and a maximum thickness of 3 km. We find that the discontinuity of the high-velocity zones is not due to the lack of some seismic phases or lose of a seismometer. We suggest that post-spreading magmatism caused these high-velocity zones. A third high-velocity zone, showing a distinctly large velocity gradient, is revealed near the continent-ocean boundary (COB). This indicates upper mantle upwelling and/or exhumation right at the COB, despite recent unsuccess in directly sampling these deep materials in the SCS.

Keywords
South China Sea, Seismic velocity structures,

Topic
Coastal Degradation and Coastal Hazard

Link: https://ifory.id/abstract/rWgP7eEjV2w6