Sedimentasi Delta Sungai Citarum, Kecamatan Muara Gembong, Kabupaten Bekasi (Sedimentation at Delta of Citarum River Muara Gembong District, Bekasi Regency)

One of land use change impacts in the downstream of Citarum watershed is sedimentation. This study aimed to determine the total suspended solid and sediment load in the downstream of Citarum River. The Total Suspended Solid (TSS) samples were taken in three locations: the inlet of Jatiluhur reservoir, the outlet of Jatiluhur reservoir, and before the Citarum River estuary. The frequency of TSS samplings was twice a year i.e during the dry season and the rainy season at 2014. Analysis of TSS content was in accordance with SNI 06-6989.3-2004 using gravimetry method. The results showed that TSS at down stream Citarum River flow was 0.44 kg/m3, TSS at the inlet of Jatiluhur reservoir was 0.20 kg/m3, and TSS at the outlet of Jatiluhur reservoir was 0.02kg/m3. The total sediment in the inlet of Jatiluhur was 1.34 x 106ton/year, in the outlet of Jatiluhur reservoir was 0.14 x 106ton/year, and the flow sediment total to the Citarum River estuary was 1.79 x 106 ton/year. The Jatiluhur reservoir could reduce the potential for sediment total flowing into the sea as much as 1.20x 106tons/year. Area of sedimentation at the delta of Citarum River was 3,828.26 ha

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Comparative analysis of spectral and luminescent properties for glasses SiO2-Al2O3-MgO-K2O-TiO2 doped with chromium ions and forsterite nano-glass ceramic have been done. Initial glasses were obtained by using a conventional melt quenching method. Glass ceramics were produced by the two-stage secondary heat treatment of initial glasses. At the first step of the heat treatment nucleation centers were formed at 700º C. At the second step there was an increase of Mg2SiO4: Cr crystalline phase. Crystalline phase composition and the crystals size were determined by X-ray diffractometer. It is shown that the crystalline phase of Mg2SiO4 (forsterite) is precipitated during the heat treatment. Valency state and the chromium ion position in a forsterite or a glassy matrix are determined according to luminescence and absorption spectra. Identification of absorption and luminescence bands in initial and heat-treated samples is carried out. The dependence between spectral and luminescent properties of chromium and heat treatment modes is examined. The results demonstrate that ions of the trivalent and tetravalent chromium are transforming to the forsterite crystalline phase during the heat treatment, and a part of them remains in the glassy phase. Presented research results can be used for the development of glasses and nanoscale glassceramic for fiber tunable lasers and broadband optical amplifiers of a near infrared range which are used in information and telecommunication technologies