Judul: Flood Susceptibility Area Mapping in East Belitung  Regency based on Geographic Information System
Abstrak: Banjir merupakan salah satu permasalahan di Kabupaten Belitung Timur, namun belum dipetakan kerawanan banjir untuk wilayah kabupaten. Peta rawan banjir termasuk langkah untuk mengurangi dampak bencana banjir yang dapat diidentifikasi dengan cepat menggunakan sistem informasi geografis dan pengindraan jauh. Tujuan penelitian ini adalah membuat peta daerah rawan banjir di Kabupaten Belitung Timur dan memvalidasinya. Identifikasi daerah rawan banjir dilakukan dengan metode skoring dan pembobotan. Validasi dilakukan terhadap gambar dampak lokasi dan data pengindraan jauh Sentinel-1. Parameter yang mempengaruhi kerawanan banjir di Kabupaten Belitung Timur adalah curah hujan, kemiringan lereng, ketinggian lahan, tutupan lahan, jenis tanah, dan buffer sungai. Hasil penelitian menyatakan Kabupaten Belitung Timur memiliki tingkat kerawanan banjir sedang yang terluas. Tingkat kerawanan rendah dan sedang terluas terdapat di Kecamatan Kelapa Kampit, sedangkan tingkat kerawanan banjir tinggi dan sangat tinggi terluas terdapat di Kecamatan Gantung. Sebanyak 12 titik dari 18 titik kejadian banjir terletak di wilayah kerawanan tinggi. Genangan banjir menurut citra Sentinel-1 teramati di lima kecamatan dengan luas terbesar di kerawanan banjir tinggi sebesar 28,97 km2., Flood is one of problems in East Belitung Regency, but the flood susceptibility has not been mapped for the region. A Flood susceptibility map helps reduce the impact of flood disasters. The map can be quickly generated using geographic information systems and remote sensing. This research aims to create a flood susceptibility map in East Belitung Regency and validate it. Flood-susceptible areas are identified using a weighted scoring method. Validation is based on impact images of flooding and remote sensing data. Parameters affecting flood susceptibility in East Belitung Regency include rainfall intensity, land slope, land elevation, land cover, soil type, and buffer distance from a river. The results indicate that East Belitung Regency has the largest area of moderate flood susceptibility. Low and moderate susceptibility has the greatest area in Kelapa Kampit District, while high and very high susceptibility has the greatest coverage in Gantung District. Twelve of eighteen identified flood points are in high susceptibility areas. According to Sentinel-1 imagery, flooding is observed in five districts, covering an area of about 28.97 km2, primarily within high susceptibility areas.
Keyword: flood susceptibility, flood susceptibility map, Sentinel-1, validation

Judul: Spatial Distribution of Inundation Floods on Belawan Coastal Area, North Sumatra Detected Using Satellite Imagery
Abstrak: Kecamatan Belawan merupakan kawasan pemukiman perkotaan padat dan memiliki resiko bahaya pasang surut air laut yang tinggi. Banjir adalah genangan air yang berasal dari laut yang terjadi di pesisir yang diakibatkan oleh pasang naik air laut. Penelitian ini bertujuan memetakan sebaran genangan banjir rob yang terjadi di Belawan, Sumatera Utara dengan menggunakan citra satelit Sentinel 1A dan data Sentinel 2A. Sebaran banjir rob diperoleh dari delineasi dua wilayah darat dan perairan menggunakan Sentinel 2A yang dilakukan penyesuaian dengan DEMNAS dan data pendukung lainnya yang mempengaruhi seperti arah angin, pasang surut, penurunan muka tanah, dan curah hujan terhadap lokasi penelitian. Hasil analisis data bulan Oktober adanya genangan dengan luas sebaran sebesar 13.185.520 m² (43,3%) sedangkan lahan yang tidak terdampak memiliki luas sebaran sebesar 16.952.760 m² (56,7%). Saat bulan November terdapat genangan yang memiliki luas sebaran sebesar 13.415.480 m² (44,4%) sedangkan lahan yang tidak terdampak memiliki luas sebaran sebesar 16.722.800 m² (55,6%). Pada bulan Desember terdapat genangan seluas 11.762.900 m² (38,9%) sedangkan lahan yang tidak terdampak memiliki luas sebaran sebesar 18.375.380 m² (61,1%). Banjir rob berdampak terhadap tutupan lahan meliputi tubuh air/kolam/rawa, sawah, perkebunan, pemukiman, dan lahan terbuka., The Belawan Subdistrict is a densely populated urban area with a high risk of tidal flooding from the sea. Flooding is the inundation of coastal areas caused by rising sea levels. This study aims to map the distribution of tidal flood inundation in Belawan, North Sumatra, using Sentinel 1A satellite imagery and Sentinel 2A data. The flood distribution was obtained by delineating two land and water areas using Sentinel 2A, adjusted with DEMNAS and other supporting data that influence the location, such as wind direction, tides, land subsidence, and rainfall. The analysis results for October showed that the flooded area covered 13,185,520 m² (43.3%) of the study area, while the non-affected land covered 16,952,760 m² (56.7%). In November, the flooded area covered 13,415,480 m² (44.4%), and the non-affected land covered 16,722,800 m² (55.6%). By December, the flooded area decreased to 11,762,900 m² (38.9%), while the non-affected land increased to 18,375,380 m² (61.1%). The tidal flooding impacted various land covers, including water bodies/ponds, rice fields, plantations, settlements, and open land.
Keyword: banjir rob, pemetaan, genangan, Belawan, Sentinel 2A, luas sebaran

Judul: Characterizations of low alloy steel sae 4422  plated with chromic acid (Cro3)
Abstrak: Characterizations of low alloy steel SAE 4422 plated with chromic acid (CrOrO3) was use Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), RD),Energy Dispersive Analysis of X-Ray (EDAX), Hardness Test and Roughness Test. Microstructures analysis exhibits cracks and grain boundaries microcracks as a characteristics of chrome metal found at plating metal. Perlite and Ferrite as grains of steel found at base metal with grain boundaries around it. Phase analysis of plating metal appropriate to chrome metal with lattice constant (a) is 2.559 Å and phase analysis of base metal appropriate to iron ferrite with lattice constant (a) is 3.318 Å. Both plating and base metal have cubic system. Chemical analysis of plating metal at surface section exhibits that cracks area have highest value of carbon element compare with grains and grains boundaries area. While chemical analysis of base metal at cross section exhibits that perlite have highest value of carbon element compare with ferrite and grain boundaries. The hardness value of plating metal at surface section and cross section are 753 and 637 VHN. While, the hardness value of base metal and interface area at cross section are 205 and 373 VHN. The roughness value at measurement points of chrome surface for as received sample are 0.445 μm. Observation used Optical Microscopy and Scanning Electron Microscopy exhibits surface irregularities combine to form surface texture of plating metal at surface section.
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