Judul: Return Period Analysis of Water Discharge for Main Rivers in Java
Abstrak: Curah hujan yang tinggi di Pulau Jawa berpengaruh terhadap besarnya debit pada aliran sungai. Debit yang melampaui kapasitas maksimal alur sungainya menyebabkan meluapnya aliran sungai tersebut yang dapat menimbulkan kerugian. Pencegahan dan penanggulangan banjir atau luapan air dapat dilakukan dengan melakukan analisis frekuensi debit sungai. Prakiraan besar debit dapat digunakan untuk mengetahui daya tahan atau daya tampung yang diperlukan untuk membangun infrastruktur yang berfungsi sebagai pencegahan atau penanggulangan banjir. Penelitian ini bertujuan menganalisis periode ulang debit sungai utama di Pulau Jawa (Bengawan Solo, Brantas, Cimanuk, Ciujung dan Serayu). Metode yang digunakan untuk menghitung periode ulang yaitu metode distribusi Normal, LogNormal, Gumbel dan Log Pearson III. Dalam penelitian ini dilakukan perhitungan periode ulang dengan mencocokan parameter statistik tiap sungai dengan syarat keempat metode distribusi tersebut. Hasilnya adalah hanya metode Log Pearson III yang memenuhi syarat untuk perhitungan periode ulang debit tiap sungai. Kenaikan debit terbesar terjadi pada kala ulang 5 tahun yang dialami oleh tiap DAS. Pada kala ulang 2, 5, 25 dan 50 tahunan di DAS Bengawan Solo, Brantas, Cimanuk dan Serayu tidak terjadi debit yang melampaui kapasitas tampung maksimalnya, sehingga tidak berpotensi terjadi kejadian banjir. Potensi kejadian banjir terjadi pada DAS Ciujung pada kala ulang 25 dan 50 tahunan dengan besar debit berurutan yaitu 2.215 m3/s dan 2.498 m3/s.
Keyword: distribution method, flood, frequency analysis, Log Pearson III, maximum discharge

Judul: Analisis Frekuensi Aliran Tinggi pada Beberapa Daerah Aliran Sungai di Pulau Jawa
Abstrak: Information about highflow frequency and its magnitude is needed for sustainable watershed management. The objectives of this research were to determine highflow threshold and to analyse highflow frequency of Ciujung, Brantas and Bengawan Solo river basin. Long term daily streamflow data were analysed using annual maximum series (AMS) and partial duration series (PDS). Exceedence frequency 5% was chosen as highflow threshold. Based on the threshold, return period of highflow from PDS and AMS was compared. Analysis result showed highflow threshold values of Bengawan Solo, Brantas and Ciujung watershed were 1,304 m3/s, 668 m3/s and 298 m3/s respectively. Log Pearson Type III was used to estimate highflow values at greater return periods. The plotting position of AMS showed smaller discharge than PDS at the same return period. While data analysis showed AMS discharge in various return period tend to be greater than PDS
Keyword: highflow threshold, highflow threshold, flood frequency analysis, return period

Judul: Pemurnian dan Karakterisasi Enzim Keratinase dari Bacillus sp. BE-1
Abstrak: The keratinase studied in this research is an extracellular protease produced by Bacillus sp. BE-1. Feather meal substrates were prepared from native chicken feather, treated by sodium hydroxide at temperature of 1000C for 15 minutes to render crude keratinase extract. The crude keratinase was then purified by 2 steps of coloumn chromatography which are Hydrophobic Interaction Chromatography (HIC) and Gel Filtration Chromatography (GFC). Butyl Sepharose (HIC) increased keratinase activity to 67-fold. Further purification using Sephacryl S200-HR (GFC) increased keratinase activity up to the range of 116-515 fold. The highest specific activity of the keratinase was 35,9 U/mg with feather meal as substrate. This keratinase can be completely inhibited by ethylene diamine tetra acetic acid (EDTA). Additon of Mn2+ increased this keratinase activity significantly (about 51-fold) while Mg2+ increased the activity slightly (about 3-fold). Zymogram analysis resulted in that the purified keratinase consisted of two proteases with molecular weight 82 kDa and >97 kDa.
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