Judul: Pengembangan indikator sistem peringatan dini dan teknik prakiraan debit banjir sungai Cimanuk, Development of some indicators of flood warning system and flood forecasting technique at Cimanuk river
Abstrak: This study was carried out in Cimanuk watershed, located in West Java. Cimanuk river flows through the district of Garut, Sumedang, Majalengka, and Indramayu. The river has three tributaries: Cilutung, Cimanukhulu, and Cipeles rivers; the outlets of each tributary are respectively at Kamun, Eretan and Warungpeti stations. The lowest flood monitoring station on Cimanuk river is at Monjot. The river caused annual floods to down stream and some of the floods caused serious damage. To reduce the damage and to anticipate floods it is necessary to develop a flood early warning system., This study was carried out in Cimanuk Watershed, located in West Java. Cimanuk river flows through the district of Garut, Sumedang, Majalengka, and Indramayu. The river has three tributaries: Cilutung, Cimanukhulu, and Cipeles rivers; the outlets of each tributary are respectively at Kamun, Eretan and Warungpeti stations. The lowest flood monitoring station on Cimanuk river at Monjot. The river caused annual the damage and to anticipate floods caused serious damage. To reduce the damage and to anticipate floods it is necessary to develop a flood early warning system.
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Judul: Penentuan Batas Ambang Curah Hujan Penyebab Banjir (Studi Kasus DAS Ciliwung Hulu)
Abstrak: One of the flood occurrences that always causes loss to the state almost every year is the Flood of Jakarta. The loss might be minimized if the flooding discharge is able to be early predicted. The objective of this study determined rainfall generating flooding. We applied multiple regression method to develop relation between rainfall and discharge in Ciliwung Hulu Sub-Watershed. Rainfall data from three stations (Gunung Mas, Citeko, and Katulampa) and flood discharge at Bendung Katulampa were used in this study. This study consist of three categories model, the first model was relation of every station against discharge Alert IV until Alert I, the second model was relation of stations against discharge in 1996 – 2008, and the last model was relation of stations against disharge which was not use zero data of rainfall or disharge with the same period. Model for estimating rainfall threshold using Multiple Linear Regression has been incompatible to be developed for flood early warning. Because small value of determination coefficien which was only less than 50%. Based on the first model the rainfall causes of flood was undeterminable. The second model gave rainfall threshold for Gunung Mas, Citeko and Katulampa as value as 183 mm, 176 mm, and 149 mm. Variance inflation factor for Gunung Mas, Citeko and Katulampa as value as 1.5, 1.4, and 1.1, p-value was 0.000, and R2 was 33.6%. The third model gave threshold rainfall as value as 253 mm, 253 mm and 125 mm, with variance inflation factor for Gunung Mas, Citeko and Katulampa as value as 1.4, 1.4, and 1.0, p-value was 0.000, with R2 was 24.6%. Based on the historical data, flood is usually happened on January and February. To minimize the loss, in that month the official functionary in upstream should be ready in reporting the discharge for the downstream official functionary.
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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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