PENGELOMPOKKAN HABITAT DASAR PERAIRAN DANGKAL BERBASIS DATA SATELIT QUICKBIRD MENGGUNAKAN ALGORITMA SELF ORGANISING MAP

Pengembangan algoritma self organising map dalam penelitian ini bertujuan untuk mengelompokkan habitat perairan dangkal berbasis data satelit Quickbird. Data primer dikumpulkan melalui data penginderaan jauh dan survey lapang, sedangkan data sekunder dikumpulkan dari penelitian yang relevan. Hasil penelitian menunjukkan bahwa klasifikasi algoritma self organising map dapat mengklaster/ mengklasifikasi citra Quickbird dari berbagai kombinasi kanal. Dari berbagai kombinasi input data setelah direduksi kolom air dengan algoritma Lyzenga, Self organising map menunjukkan hasil klaster yang relatif baik. Algoritma Lyzenga dapat mengelompokkan habitat perairan dangkal 6 (enam) kelas habitat, yaitu karang mati (merah), karang hidup (hijau), lamun (orange), pasir (kuning), dan habitat campuran (hijau muda), daratan (hitam) dan perairan (biru). Setelah menggunakan self organising map secara visual terlihat 6 kelas habitat yang berbeda dari Lyzenga, yaitu karang mati (kuning), karang hidup (cyan), lamun (ungu), pasir (kuning), dan habitat campuran (biru), daratan (hijau) dan perairan (coklat). Algoritma self organising map dapat mengurangi kesalahan tematik habitat perairan dangkal dan sangat membantu proses ekstraksi ROI (region of interset) untuk reklasifikasi lebih lanjut dengan teknik klasifikasi supervised

DINAMIKA GENANGAN PESISIR JAKARTA BERDASARKAN DATA MULTI-TEMPORAL SATELIT MENGGUNAKAN INDEKS AIR DAN POLARISASI RADAR

Combining baseline data of remote sensing systems active and passive has many advantages in monitoring coastal inundation dynamically. It has advanced the surface water information gaps in coastal areas, especially areas covered by clouds and shadows. The main objective of this study was to assess the dynamics of coastal inundation in Jakarta based on multi-temporal data optics of Landsat 8 and Synthetic Aperture Radar (SAR) Sentinel 1A. The method of this research used two water index algorithms. They are Modified Normalized Difference Water Index (MNDWI) and Dynamic Surface Water Extent (DSWE) based on spectral reflectance values and empirical formulas. The other method is using the coefficient backscattering of water from a single polarization of Vertical Verticals (VV) and Vertical Horizontal (VH). The study results show that the use of both satellite data baseline of 8, 9, 15, and 16 days is quite effective, applying inundation dynamics for 8-49 days. Based on the threshold value of MNDWI > 0.123 and the backscattering coefficient of -19dB are quite efficient to extract satellite data information. The empirical algorithms result in the feature of inundation, especially along the coastal dikes, reservoirs, mangrove ecosystems, and built-up lands. Satellite monitoring results show that the peak of inundation occurred on 30 May 2016 and was still visible on 15 June 2016. The combination of remote sensing methods is quite effective and efficient for monitoring inundation dynamically.Kombinasi baseline data pengindraan jauh sistem aktif dan pasif memiliki banyak keuntungan dalam pemantauan dinamika genangan pesisir. Kedua jenis sensor satelit mengatasi kesenjangan informasi genangan, terutama pada area yang ditutupi awan/bayangan. Tujuan utama penelitian ini adalah untuk mengkaji dinamika genangan di wilayah pesisir Jakarta berdasarkan data multi-temporal sensor optik dari Landsat 8 dan Synthetic Aperture Radar (SAR) Sentinel 1A. Metode penelitian ini menggunakan dua algoritma indeks air. Algoritma tersebut yaitu Modified Normalized Difference Water Index (MNDWI) dan Dynamic Surface Water Extent (DSWE) berdasarkan nilai spektral reflektansi dan formula empirik. Metode lainnya adalah menggunakan nilai rata-rata koefisien backscatter air dari analisis polarisasi tunggal Vertikal Vertikal (VV) dan Vertikal Horisontal (VH). Hasil studi menunjukkan bahwa penggunaan kedua tipe data satelit dengan baseline data 8, 9, 15 dan 16 hari cukup efektif memantau dinamika genangan selama 8-49 hari, termasuk area yang tertutup awan dan bayangan. Berdasarkan nilai threshold dari MNDWI >0,123 dan koefisien backscattering air -19dB cukup efisien digunakan untuk mengesktrak informasi data satelit. Algoritma empiris tersebut menghasilkan kenampakan genangan, terutama di sepanjang tanggul pantai, waduk, ekosistem mangrove dan lahan terbangun. Hasil pemantauan satelit menunjukkan bahwa puncak genangan terjadi pada 30 Mei 2016 dan masih terlihat pada 15 Juni 2016. Kombinasi metode pengindraan jauh tersebut cukup efektif dan efisien untuk memantau genangan secara dinamis

ASSESSMENT OF ATMOSPHERIC CORRECTION METHODS FOR OPTIMIZING HAZY SATELLITE IMAGERIES

The purpose of this research is to examine suitability of three types of haze correction methods toward distinctness of surface objects in land cover. Considering the formation of haze therefore the main research are divided into both region namely rural assumed as vegetation and urban assumed as non vegetation area. Region of interest for rural selected Balaraja and urban selected Penjaringan. Haze imagery reduction utilized techniques such as Dark Object Substration, Virtual Cloud Point and Histogram Match. By applying an equation of Haze Optimized Transformation HOT = DNbluesin(∂)-DNredcos(∂), the main result of this research includes: in the case of AVNIR-Rural, VCP has good results on Band 1 while the HM has good results on band 2, 3 and 4, therefore in the case of Avnir-Rural can be applied to HM. in the case of AVNIR-Urban, DOS has good result on band 1, 2 and 3 meanwhile HM has good results on band 4, therefore in the case of AVNIR-Urban can be applied to DOS. In the case of Landsat-Rural, DOS has good result on band 1, 2 and 6 meanwhile VCP has good results on band 4 and 5 and the smallest average value of HOT is 106.547 by VCP, therefore in the case of Lansat-Rural can be applied to DOS and VCP. In the case of Landsat-Urban, DOS has good result on band 1, 2 and 6 meanwhile VCP has good results on band 3, 4 and 5, therefore in the case of Landsat-Urban can be applied to VCP.   Tujuan penelitian ini untuk menguji kesesuaian tiga jenis metode koreksi haze terhadap kejelasan obyek permukaan di wilayah tutupan vegetasi dan non vegetasi, berkenaan menghilangkan haze di wilayah citra satelit optis yang memiliki karakteristik tertentu dan diduga proses pembentukan partikel hazenya berbeda. Sehingga daerah penelitian dibagi menjadi wilayah rural yang diasumsikan sebagai daerah vegetasi dan urban sebagai non vegetasi. Pedesaan terpilih kecamatan Balaraja dan Perkotaan terpilih kecamatan Penjaringan. Tiap lokasi menggunakan Avnir-2 dan Landsat 7. Untuk mendapatkan hasil pengurangan kabut di kedua lokasi tersebut digunakan metode Dark Object Substraction (DOS), Virtual Cloud Point (VCP) dan histogram Match (HM) dengan persamaan  nilai optimasi kabut HOT = DNbluesin(∂)-DNredcos(∂). hasil penelitian ini sebagai berikut: dalam hal AVNIR-Rural, VCP memiliki hasil yang baik di Band-1 sedangkan HM memiliki hasil yang baik pada band-2, 3 dan 4 sehingga dalam kasus AVNIR-Rural dapat diterapkan HM. Dalam hal AVNIR-Urban, DOS memiliki hasil yang baik pada band-1, 2 dan 3. Sementara HM memiliki hasil yang baik pada band 4, sehingga dalam kasus AVNIR-Urban dapat diterapkan DOS. Dalam kasus Landsat-Rural, DOS memiliki hasil yang baik pada band-1, 2 dan 6, Sementara VCP memiliki hasil yang baik pada band 4 dan 5. Sehingga dalam kasus Landsat-Rural dapat diterapkan DOS. Dalam hal Landsat-Urban, DOS memiliki hasil yang baik pada band-1, 2 dan 6 sedangkan VCP  memiliki hasil yang baik pada band-3, 4, dan 5. Sehingga dalam hal Landsat-Urban dapat diterapkan VCP. Semakin baik citra hasil koreksi semakin kecil nilai optimasi kabut, nilai rata–rata terkecil adalah 106,547 dengan VCP di Landsat-Rural

The kinematics of crustal deformation in Java from GPS observations: Implications for fault slip partitioning

Our understanding of seismic risk in Java has been focused primarily on the subduction zone, where the seismic records during the last century have shown the occurrence of a number of tsunami earthquakes. However, the potential of the existence of active crustal structures within the island of Java itself is less well known. Historical archives show the occurrence of several devastating earthquake ruptures north of the volcanic arc in west Java during the 18th and the 19th centuries, suggesting the existence of active faults that need to be identified in order to guide seismic hazard assessment. Here we use geodetic constraints from the Global Positioning System (GPS) to quantify the present day crustal deformation in Java. The GPS velocities reveal a homogeneous counterclockwise rotation of the Java Block independent of Sunda Block, consistent with a NE–SW convergence between the Australian Plate and southeast Asia. Continuous GPS observations show a time-dependent change in the linear rate of surface motion in west Java, which we interpret as an ongoing long-term post-seismic deformation following the 2006 Mw 7.7 Java earthquake. We use an elastic block model in combination with a viscoelastic model to correct for this post-seismic transient and derive the long-term inter-seismic velocity, which we interpret as a combination of tectonic block motions and crustal faults strain related deformation. There is a north–south gradient in the resulting velocity field with a decrease in the magnitude towards the North across the Kendeng Thrust in the east and the Baribis Thrust in the west. We suggest that the Baribis Thrust is active and accommodating a slow relative motion between Java and the Sunda Block at about 5 ± 0.2 mm/yr. We propose a kinematic model of convergence of the Australian Plate and the Sunda Block, involving a slip partitioning between the Java Trench and a left-lateral structure extending E–W along Java with most of the convergence being accommodated by the Java megathrust, and a much smaller parallel motion accommodated along the Baribis (∼5 ± 0.2 mm/yr) and Kendeng (∼2.3 ± 0.7 mm/yr) Thrusts. Our study highlights a correlation between the geodetically inferred active faults and historical seismic catalogs, emphasizing the importance of considering crustal fault activity within Java in future seismic assessmentsThis research was supported under the Australian Research Council’s Linkage Projects funding scheme, grant LP110100525 and the Australian Dept. Foreign Affairs Grant 71982. A.K. was partly supported by the ARC Linkage grant LP130100134