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: Spatial Distribution of Tidal Flood Areas in Coastal Areas of Pandeglang Regency, Banten Using Landsat 8 OLI Imagery
Abstrak: Banjir rob merupakan kejadian meluapnya air laut saat pasang sehingga menyebabkan adanya genangan pada daratan yang memiliki elevasi tanah yang rendah. Fenomena ini sering ditemukan pada wilayah pesisir, seperti di pesisir Kabupaten Pandeglang. Penelitian ini bertujuan untuk mengetahui sebaran luasan banjir rob di Pesisir Kabupaten Pandeglang, Banten menggunakan metode sistem informasi geospasial. Sebaran genangan banjir diperoleh dari pemisahan wilayah daratan dan perairan menggunakan ekstraksi citra Landsat 8 OLI yang akan disesuaikan dengan data elevasi tanah dari DEMNAS dan faktor lain yang mempengaruhinya seperti penurunan muka tanah, kecepatan dan arah angin bertiup, curah hujan dan pasang surut pada lokasi penelitian. Dari hasil analisis data pada bulan Desember didapatkan bahwa, pasang air laut tertinggi memiliki ketinggian 0,736 m, curah hujan tertinggi pada sebesar 25,6 mm per hari, dengan arah angin yang didominasi menuju ke arah timur dengan kecepatan 3.60 m/s – 8.80 m/s dan penurunan muka tanah terbesar sebesar 14 cm dari tahun 2019 – 2020 yang berada di Kecamatan Panimbang. Berdasarkan penelitian ini dapat diperlihatkan bahwa hasil sebaran genangan banjir di Kabupaten Pandeglang memiliki luasan sebesar 1.232 ha atau 3,64% dari luasan pesisir Kabupaten Pandeglang dengan 4 kecamatan yang terdampak banjir., Coastal flooding is the overflow of seawater during high tide caused inundation in a low elevation area. This phenomenon is often found in coastal areas, such as on the coast of Pandeglang Regency. This study aimed to determine the distribution of the tidal flood area in the Pandeglang Coast, Banten using the geospatial information system method. The distribution of flood inundation is obtained from the separation of land and water areas with the use of Landsat 8 OLI imagery extraction which will be adjusted to land elevation data from DEMNAS and other factors that influence it such as land subsidence, wind speed and direction, rainfall and tides at the research location. After the analysis was done results in December 2020 showed that the highest tide happened was 0.736 m, The highest rainfall was 25.6 mm per day, with the wind direction dominated towards the west with a speed of 3.60 m/s – 8.80 m/s and the largest land subsidence is 14 cm in 2019 - 2020 which is located in Panimbang District. After combining the data, the distribution of flood inundation in Pandeglang Regency showed that there was 1,232 ha or 3.64% of an inundated area in the coastal area of Pandeglang Regency with 4 sub-districts affected by the flood.
Keyword: Banjir rob, Luasan Spasial, Penurunan Muka Tanah, Kabupaten Pandeglang

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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