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Abstrak :
Penurunan tanah memiliki dampak yang besar terhadap infrastruktur seperti mengubah geometri permukaan. Pergerakan turunnya tanah secara vertikal (subsidence) merupakan salah satu dari banyak faktor yang menyebabkan kerusakan infrastruktur baik yang diakibatkan oleh pergerakan secara alami seperti gempa ataupun buatan seperti aktivitas pertambangan. Penelitian ini bertujuan untuk analisis penyebab subsidence melalui pemodelan 2D tomografi seismik dan 3D tomografi resistivitas di Perumahan Tranquility, Depok.  Metode tomografi seismik refraksi yang dilakukan dalam penelitian ini bertujuan untuk mengidentifikasi zona subsidence berdasarkan parameter kecepatan tanah sedangkan tomografi resistivitas bertujuan untuk melihat distribusi anomaly resistivitas zona rawan subsidence. Di lokasi terjadinya subsidence telah dilakukan pengambilan data seismik refraksi dan data geolistrik resistivitas ERT. Nilai waktu tiba (arrival time) dari data seismik refraksi digunakan sebagai parameter dalam proses tomografi waktu tunda. Hasil dari pengolahan seismik refraksi berupa model kecepatan (velocity map) lapisan bawah permukaan dan grafik waktu versus jarak dari waktu tersimulasi dan waktu terobservasi di setiap lintasan refraksi. Kemudian, hasil pengolahan tomografi seismik di korelasikan dengan data pengolahan ERT berupa penampang sebaran resistivitas bawah permukaan. Analisis hasil pengolahan kedua data tersebut didapatkan bahwa terdapat 3 tipe lapisan yaitu lapisan batuan lepas (unconsolidated sediment/loose soil), lapisan batuan pasir-kerikil (sandy gravel), dan lapisan akuifer dengan kemungkinan batuan silt-clay. Lapisan batuan lepas dengan kedalaman 0-6 meter mengalami penebalan dari arah barat daya hingga timur laut dengan ketebalan rata-rata 4 meter dan memiliki nilai resistivitas antara 17-35 ohm.m dan kecepatan rambat gelombangnya 300-340. Lapisan batuan pasir-kerikil dengan kedalaman 6-12 meter dan ketebalan nya meningkat dari arah timur laut hingga barat daya. Lapisan ini memiliki nilai resistivitas 55-110 ohm.m dan kecepatan rambat gelombangnya > 340. Lapisan akuifer berada pada kedalaman 13-30 meter dengan geometri panjang 40 meter dengan nilai resistivitas 0-15 ohm.m. Lapisan akuifer ini diinterpretasikan sebagai lapisan tipe batuan silt-clay. Geometri dari lapisan batuan pasir-kerikil lintasan ERT menunjukan adanya proses pensesaran tektonik minor/zona fraktur pada bagian barat daya dan timur laut dengan ciri blok respon resistivitas yang menebal dan diskontinyu. Geometri dari pensesaran ini termodelkan dalam model resistivitas 3D. ......Subsidence has major impacts on infrastructure such as changing surface geometry. Vertical subsidence movement is one of the many factors that cause damage to infrastructure whether caused by natural movements such as earthquakes or artificial movements such as mining activities. This research aims to analyze the causes of subsidence through 2D seismic tomography and 3D resistivity tomography modeling in Tranquility Housing, Depok.  The refraction seismic tomography method carried out in this study aims to identify subsidence zones based on ground velocity parameters while resistivity tomography aims to see the distribution of resistivity anomalies in subsidence-prone zones. At the location of subsidence, refraction seismic data and ERT resistivity geoelectric data have been collected. The arrival time value of refraction seismic data is used as a parameter in the time-delay tomography process. The refraction seismic processing results in a velocity map of the subsurface and a time versus distance graph of the simulated and observed times in each refraction trajectory. Then, the results of seismic tomography processing are correlated with ERT processing data in the form of subsurface resistivity distribution cross-sections. Analysis of the results of the processing of the two data obtained that there are 3 types of layers: unconsolidated sediment/loose soil layer, sandy gravel layer, and aquifer layer with possible silt - clay rocks. The loose rock layer with a depth of 0-6 meters thickens from the southwest to the northeast with an average thickness of 4 meters and has a resistivity value between 17 - 35 ohm.m and a wave propagation speed of 300 - 340  The sand-gravel layer is 6-12 meters deep and its thickness increases from the northeast to the southwest. This layer has a resistivity value of 55-110 ohm.m and a wave propagation velocity of > 340 m  The aquifer layer is at a depth of 13-30 meters with a geometry length of 40 meters with a resistivity value of 0-15 ohm.m. This aquifer layer is interpreted as a silt-clay rock type layer. The geometry of the ERT track sand-gravel layer shows a minor tectonic faulting process/fracture zone in the southwest and northeast with thickened and discontinuous resistivity response blocks. The geometry of this faulting is modeled in the 3D model.

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ABSTRAK
North Coast of Java Island continues to experience coastal dynamics which resulted significant coastline erosion problems. According to the Ministry of Marine and Fisheries data (KKP), from 100 locations of coastline erosion in 17 provinces of Indonesia, North Coast of Java Island suffered the worst erosion, reaching 745 km or 44 percent of total coastline length. The shoreline retreat can be caused by three factors: sea level rise, erosion and land subsidence. The aim of this research was to determine the correlation between sediment equilibrium in coastal cells and the initial hypothesis of land subsidence which caused a coastline retreat. The method to calculate sediment equilibrium uses hypothetical sediment budget model. Modeling itself is done along the North Coast of Java. LITDRIFT model of Longshore Sediment Drift is employed to assess the coastline profile. The result of the research shows that there is anomalous model that is the condition of sediment is surplus but the condition of the field is backward. Several locations experienced a sediment surplus but experienced a coastline retreat, and after comparison with field observations and secondary data there was evidence of land subsidence: Pondok Bali Beach, Randusongo Beach, Muara Reja Beach, Depok Beach, Slamaran Beach, Jeruksari-Mulyorejo Beach and Sriwulan Beach. This models result can be used as an initial indicator of the land subsidence causing the coastline to retreat. In order to solve the erosion and sedimentation problem, the detail study with more comprehensive parameter needs to be conducted

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ABSTRACT ABSTRACT
Study of time lapse or 4D microgravity had been done to detect subsidence zone and its rate between 2014 and 2018 in Jakarta. Jakarta mostly covered by quaternary alluvium fan supplied from southern part of this city. Subsidence happened by several factors including excessive water exploitation, surface load, and the natural sinking properties of unconsolidated alluvium. By combining Simple Bouguer Anomaly SBA equation and gravity gradiometry methods, we can get the Bouguer density of 2.33 g cm3. Since subsidence occurred on near surface, regional gravity anomaly has been separated from SBA by combining spectrum analysis and moving average methods after implementing Fourier transform. The effect of groundwater movements removed from 4D microgravity anomaly with correlation to groundwater well data. The result shows that subsidence occurred all over the coastal area of Jakarta, with highest rate in North Jakarta 7 20 cm year . There also negative 4D microgravity anomaly in southern part of Jakarta that related to ground level uplifting.

Abstrak :
Yogyakarta merupakan kota dengan pertumbuhan penduduk yang meningkat tiap tahunnya. Hal ini membuat kebutuhan akan lahan permukiman dan air tanah meningkat. Alih guna lahan menjadi permukiman atau gedung membuat beban tanah meningkat serta menurunkan area resapan air. Penggunaan air tanah yang meningkat membuat Kota Yogyakarta mengalami penurunan muka air tanah hingga 50 cm per tahun. Bertambahnya beban tanah dan menurunnya muka air tanah merupakan implikasi terjadinya penurunan permukaan tanah. Teknik Interferometric Synthetic Aperture Radar (InSAR) dan Small Baseline Subset (SBAS) digunakan pada citra satelit radar Sentinel-1 untuk menunjukkan lokasi dan pola penurunan permukaan tanah yang terjadi. Perubahan muka air tanah, perubahan penggunaan tanah, serta kepadatan bangunan juga digunakan untuk mengetahui pola dan faktor penyebab penurunan permukaan tanah yang terjadi. Hasil dari penelitian ini adalah data LiCSAR yang telah diolah dapat menggambarkan adanya dinamika perubahan ketinggian permukaan tanah (PKPT). Penurunan permukaan tanah (PPT) terjadi pada beberapa sumur yang mengalami penurunan tren muka air tanah dan wilayah penurunan permukaan tanah (PPT) berada pada penggunaan tanah jenis permukiman, hutan lahan kering, dan sawah. Hasil analisis statistik dan deskriptif menunjukkan tidak ada hubungan antara perubahan ketinggian permukaan tanah (PKPT) dengan perubahan muka air tanah, kepadatan bangunan, dan perubahan penggunaan tanah ......Yogyakarta is a city with population growth that increases every year. This causes the need for residential land and groundwater to increase. The conversion of land to a settlement or building causes the land load to increase and reduces the water catchment area. The increasing use of groundwater has made the city of Yogyakarta experience a drop in groundwater level of up to 50 cm per year. Increasing soil load and decreasing groundwater level are implications of land subsidence. Interferometric Synthetic Aperture Radar (InSAR) and Small Baseline Subset (SBAS) techniques are used on Sentinel-1 radar satellite images to show the location and pattern of subsidence that has occurred. Changes in groundwater level, changes in land use, and density of buildings are also used to determine patterns and factors that cause subsidence to occur. The result of this research is that the processed LiCSAR data can describe the dynamics of changes in ground level. Land subsidence occurred in several wells that experienced a decrease in the trend of groundwater levels and the area of land subsidence was in land use types for settlements, dry land forests, and rice fields. The results of statistical and descriptive analysis show that there is no relationship between changes in ground level with changes in groundwater level, building density, and changes in land use

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ABSTRAK
Area pesisir seperti Jakarta Utara merupakan daerah yang pembangunanya sangat cepat dalam segi konstruksi. Hal ini mengakibatkan penurunan lapisan tanah dengan tingkat kompresibilitas yang tinggi, contohnya adalah lapisan tanah lempung pesisir. Daerah Jakarta Utara umumnya memiliki jenis tanah lempung dengan kompresibilitas yang tinggi. Konsolidasi merupakan proses pemadatan yang terjadi pada tanah akibat kemampuan tanah tersebut untuk terkompresi. Tanah normally consolidated (NC) merupakan jenis tanah yang belum pernah mengalami pengurangan tegangan lapisan tanah di atasnya, sedangkan tanah over-consolidated merupakan jenis tanah yang menerima tegangan yang jauh lebih besar dari tegangan yang diterima pada masa sekarang. Kecepatan konsolidasi sangat bergantung pada parameter kompresibilitas. Penurunan tanah di daerah pesisir Jakarta Utara dapat diestimasi menggunakan kecepatan konsolidasi tanah di daerah tersebut. Maka dari itu, penelitian untuk mengidentifikasi parameter karakteristik disertai perbandingan dengan indeks plastisitas (IP) perlu dilakukan. Penelitian ini diawali dengan melakukan pengujian laboratorium terhadap sampel tanah tak terganggu yang diambil sampai kedalaman 50 meter di Kecamatan Kamal Muara, Jakarta Utara. Metode yang digunakan adalah pengujian konsolidasi dengan oedometer untuk mendapatkan nilai cc dan P c. Setelah mendapatkan nilai parameter konsolidasi selanjutnya dilakukan pengujian triaxial CU untuk mendapatkan hubungan tegangan-regangan dan stress path untuk menentukan kondisi yield menggunakan Critical State Method, Nilai parameter yang didapat dari CSM dapat diaplikasikan untuk design menggunakan software karena lebih detail daripada modul mohr-coulomb. Adapun hasil penelitian ini yaitu tanah memiliki nilai plastisitas tinggi dengan PI 33-50%. Tanah permukaan sampai kedalaman 13 m memiliki nilai indeks kompresibilitas cc yang tinggi yaitu berkisar antara 0.46-0.77. Sedangkan tanah pada kedalaman di bawah 13 m memiliki nilai cc yang rendah. Tanah mengalami yield pada saat =144-159 kPa dan q=53-76 kPa dengan nilai Г sebesar 73 cm3.

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ABSTRACT
Northern Jakarta coastal area has rapid development in construction segment. This case affected land subsidence with high compressibility, due to residual clay found on the coastal area. Northern Jakarta covered by clay with high compressibility index. Consolidation is compacting proccess occurred by soil ability to be compressed caused by loss of pore water pressure. Rate of consolidation based on the compressibility parameters. Land subsidence at Northern Jakarta coastal area can be estimated by rate of consolidation in that area. Based on that, the research to idedntified characteristic parameters compared with plasticity index is needed to be held. This research is started by doing laboratory research by testing undisturbed and disturbed sample of soil from that area taken to 50 m depth in Kamal Muara district, Northern Jakarta. Consolidation test using oedometer has be done to get parameters cc and P c. After consolidation parameters are identified, triaxial CU test is done to identify the correlation between stress-strain and stress path to identify yield condition using Critical State Method. Parameters from CSM can be applied in design using software because its more accurate than mohr-coulomb modul3. The result of this research is the soil has a very high plasticity index around 33-50 persen. From surface layer to 13 m depth has compressibility number cc around 0.46-0.77. Therefore layers below 13 m has lower cc number. Soils got yielding at p=144-159 kPa and q=53-76 kPa with Г number is 73 cm3.

Abstrak :
Estimation of land subsidence induced by groundwater extraction has been observed by some researcher using field instrumentation as well as a spatial mapping technique. Among the six Asian cities (Bangkok, Jakarta, Manila, Osaka, Seoul, Taipei and Tokyo), the rate of land subsidence in Jakarta is higher in the period 1900-2010 from the previous study. In order to improve appropriate monitoring system and the comprehensive result for subsidence measurement, tools for subsidence awareness-raising to government and society are needed. This paper aims to study a benchmark and sustainable countermeasure analysis of land subsidence induced by ground water extraction in urban areas of Jakarta city, using continuous monitoring system and integrated data management system. Measuring of land subsidence using field monitoring such as extensometer, leveling survey (GPS geodetic) and observation wells, was conducted in some location in North Jakarta from 1990 to 2016. The result from visual observation reached an average land subsidence rate 1.65 cm/year, while GPS geodetic measurement range from 0-12 cm/year. Monitoring from seven extensometer sensors installed in different borehole elevation reached subsidence 0.66 cm in average. Meanwhile, groundwater surface level ranged at 0.6 meters until 44 meters from surface and the deepest is in Bintaro - South Tangerang area. Data analysis conducted with computer simulation to investigate the inter-connection between land subsidence and groundwater extraction. Obviously, land subsidence has a strong associated with groundwater extraction. Integrated data management systems, including data sharing are needed to improve appropriate monitoring system of land subsidence in Jakarta.

Abstrak :
Pertumbuhan Jakarta yang semakin pesat menyebabkan pembangunan di Jakarta terus meningkat dan menimbulkan permasalahan penurunan muka tanah. Penurunan muka tanah sendiri dapat berpengaruh terhadap wilayah banjir, yakni dapat mempengaruhi kedalaman dan durasi banjir. Jakarta Barat, khususnya wilayah Rawa Buaya, merupakan salah satu wilayah yang mengalami permasalahan penurunan muka tanah dan banjir. Penelitian ini bertujuan untuk mengkaji korelasi antara penurunan muka tanah dengan wilayah banjir di Rawa Buaya.Metodologi yang digunakan adalah dengan mengkorelasikan antara data sekunder titik pengamatan penurunan tanah yang diinterpolasi dan data kedalam dan durasi banjir yang diperoleh dari hasil survei lapang. Dengan menggunakan analisis autokorelasi spasial, korelasi antara penurunan muka tanah dengan kedalaman dan durasi banjir hanya terjadi di sebagian kecil saja dari wilayah Rawa Buaya. Hal ini ditunjukkan dengan nilai indeks Moran’s I sebesar 0,361 dan 0,378 yang berarti memiliki korelasi spasial yang lemah. Pengaruh penurunan muka tanah terhadap kedalaman dan durasi banjir yang ditunjukkan dengan nilai R2 masing-masing hanya sebesar 13,1 persen dan 14,4 persen. Wilayah yang memiliki korelasi antara penurunan tanah dan wilayah banjir ada dibagian tengah hingga utara Rawa Buaya.

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The rapid growth of Jakarta led to construction's rise and caused land subsidence problems. Land subsidence it self can work on the flood areas, which can affect the depth and duration of flooding. West Jakarta, particularly Rawa Buaya is a region with land subsidence and flooding's problems. This study aimed to assess the correlation between land subsidence and flood areas in Rawa Buaya. The methodology used is correlation between secondary data of land subsidence's observations points that are interpolated and data of flooding’s depth and duration that are obtained from surveys. By using spatial autocorrelation analysis, the correlation between land subsidence and flood’s depth and duration only occurs in a small fraction of Rawa Buaya. This is indicated by the values of Moran's I index that are 0.361 and 0.378, which means having a weak spatial correlation. The influence of land subsidence on flood’s depth and duration was indicated by R2's values that are 13.1 percent and 14.4 percent. The regions that has correlation between land subsidence and flooding there in the middle region to the north of Rawa Buaya.

Abstrak :
Telah dilakukan penelitian tentang laju penurunan muka tanah yang terjadi di Jakarta pada periode tahun 2018 – 2023. Laju penurunan ini dikorelasikan dengan penambahan volume penggunaan air tanah akibat pertumbuhan penduduk di Jakarta. Volume penggunaan air tanah di Jakarta didapatkan dengan mengurangkan kebutuhan air bersih dengan volume penggunaan air pipa (PAM JAYA) selama tahun 2018 – 2023. Laju pergerakan muka tanah dihitung berdasarkan pengukuran mikrogravitasi 4D yang dilakukan antara tahun 2018 dan 2023. Hasil penelitian menunjukkan bahwa Kecamatan Menteng mengalami penurunan muka tanah cukup tinggi dengan laju sebesar 8.4 cm/tahun dan Kecamatan Jatinegara mengalami kenaikan muka tanah paling tinggi dengan laju sebesar 10.3 cm/tahun. Terdapat korelasi linier antara volume penggunaan air tanah dengan laju penurunan muka tanah di Jakarta. Semakin banyak jumlah penduduk, semakin banyak air tanah yang digunakan, maka laju penurunan muka tanah akan semakin besar. ......A study has been conducted on the rate of land subsidence occurring in Jakarta during the period from 2018 to 2023. This subsidence rate is correlated with the increase in the volume of groundwater usage due to population growth in Jakarta. The volume of groundwater usage in Jakarta is determined by subtracting the volume of piped water usage (PAM JAYA) from the total demand for clean water during 2018 to 2023. The rate of land subsidence is calculated based on 4D microgravity measurements conducted in 2018 and 2023. The results show that the Menteng district experienced a significant land subsidence with a rate of 8.4 cm/year, while the Jatinegara district experienced the highest land uplift with a rate of 10.3 cm/year. There is a linear correlation between the volume of groundwater usage and the rate of land subsidence in Jakarta. As the population increases, the more groundwater is used, the greater the rate of land subsidence will be.

Abstrak :
DKI Jakarta merupakan ibukota negara dengan jumlah populasi 10,56 juta jiwa. Tingginya populasi menyebabkan tingginya ektraksi air tanah yang dapat menyebabkan penurunan muka tanah akibat berkurangnya volume tanah. Penurunan muka tanah dapat disebabkan oleh kondisi geologi berupa konsolidasi aluvium, ektraksi air tanah, bangunan dan infrastruktur, serta aktivitas tektonik. Penurunan muka tanah dapat memberikan dampak negatif kepada lingkungan dan masyarakat, seperti rusaknya bangunan dan infrastruktur, serta banjir rob. Oleh karena itu, dilakukan penelitian penurunan muka tanah di DKI Jakarta dengan bertujuan mengetahui laju penurunan muka tanah beserta dengan pola persebarannya agar dapat dijadikan acuan dalam perencanaan tata ruang kota. Metode yang digunakan adalah metode Differential Interferometry Synthetic Aperture RADAR (DInSAR) menggunakan data citra SAR Sentinel-1A untuk mengetahui nilai kelajuan penurunan muka tanah beserta dengan pola persebarannya pada periode 2019, 2020, dan 2021 dan didukung oleh metode gravitasi untuk melihat penurunan muka tanah berdasarkan perbedaan densitas. Berdasarkan hasil pengolahan metode DInSAR diperoleh laju penurunan muka tanah pada tahun 2019, 2020, dan 2021 masing-masing sebesar 120 mm/tahun, 70 mm/tahun, dan 60 mm/tahun, serta kelajuan penurunan muka tanah rata-rata sebesar 83,3 mm/tahun. Sedangkan berdasarkan hasil pengolahan metode gravitasi terdapat peningkatan anomali gravitasi yang mengindikasikan adanya penurunan muka tanah akibat berkurangnya volume tanah. ......DKI Jakarta is the Indonesia capital city with 10.56 million populations. The high populations could cause a high groundwater extraction that effects land subsidence because the reducing soil volume. Land subsidence can be caused by several factors, including geological conditions in alluvial consolidation, groundwater extraction, buildings and infrastructure, also tectonic activity. Land subsidence can negatively impact to the environment and society, damaging the infrastructure and tidal flooding. The research that related to land subsidence in DKI Jakarta aims to determine the rate of land subsidence along with its distribution pattern to be the reference in urban spatial planning. This research utilizes Differential Interferometry Synthetic Aperture RADAR (DInSAR) collecting SAR Sentinel-1A image data to determine the land subsidence rates and its distribution pattern in 2019, 2020, and 2021, supported by the gravity method to see the changes in the gravitational anomaly. From the DInSAR data, the land subsidence rate in 2019, 2020, and 2021 are 120 mm/year, 70 mm/year, 60 mm/year, and the average rate is 83.3 mm/year. But in fact, the gravitational data notes, the gravitational anomaly increase which indicated a land subsidence impacted by increasing density caused by the reduced volume of the soil.