Studi Pengendalian Banjir Kali Lamong Di Kabupaten Gresik

Pratomo, Dian Arief Pramudya (2017) Studi Pengendalian Banjir Kali Lamong Di Kabupaten Gresik. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kali Lamong merupakan sungai yang dikelola oleh Balai Besar Wilayah Sungai Bengawan Solo. DAS Kali Lamong terdiri atas Kabupaten Lamongan, Kabupaten Mojokerto, Kabupaten Gresik dan Kota Surabaya. Pada musim hujan tiap tahun terjadi luapan di Kali Lamong, akibatnya aktivitas masyarakat di daerah sekitarnya terganggu. Sejumlah upaya dilakukan pemerintah untuk mengurangi banjir, namun banjir tetap terjadi. Padahal sebagai salah satu daerah industri penting di Jawa Timur seharusnya Kabupaten Gresik aman dari ancaman banjir. Dalam tugas akhir ini debit banjir rencana didapat dari hasil analisis hidrologi terhadap data curah hujan harian. Dalam analisis tersebut, periode ulang debit banjir rencana adalah 25 tahunan. Selanjutnya kapasitas Kali Lamong dihitung dengan HEC-RAS. Dengan membandingkan kapasitas Kali Lamong dan debit banjir rencana, titik banjir di Kali Lamong dapat diketahui. Untuk mengatasi hal tersebut direncanakan sejumlah alternatif pengendalian banjir. Alternatif pertama adalah normalisasi dengan lebar dasar sungai 20 – 70 meter. Alternatif kedua, menggunakan normalisasi dengan lebar dasar sungai 20 – 40 meter dan pengerukan yang didasarkan dengan kemiringan dasar sungai rencana yang telah direncanakan. Alternatif ketiga memiliki kriteria seperti alternatif kedua dengan penambahan tanggul dengan tinggi maksimal 3 meter. Keempat, didesain serupa dengan alternatif ketiga namun tidak ada batasan untuk tinggi maksimum tanggul. Lalu keempat alternatif tersebut dianalisis untuk mengetahui kemampuan Kali Lamong mengalirkan debit banjir rencana. Berdasarkan hasil analisis dari keempat alternatif, dapat disimpulkan bahwa alternatif keempat adalah yang terbaik. Hal tersebut karena banjir tidak terjadi lagi di Kali Lamong setelah alternatif keempat digunakan. Pada alternatif keempat, di KM 4,6 direncanakan penambahan tanggul setinggi 5 meter terhadap elevasi tepi sungai eksisting atau 6,76 meter dari dasar sungai. Dengan demikian elevasi puncak tanggul berada pada +3,04. Selain peninggian tanggul, normalisasi didesain selebar 20 meter pada KM 38 – KM 22,9; 25 meter pada KM 22,8 – KM 18,8; 30 meter pada KM 18,7 – KM 10,2; 35 meter pada KM 10,1 – KM 1,9; dan 40 meter pada KM 1,8 – KM 0. =============================================================Lamong river is a river that managed by Bengawan Solo River Management Board. The Lamong river watershed consists of Lamongan Regency, Mojokerto Regency, Gresik Regency and Surabaya City are part of Lamong river watershed. The activity of people around Lamong river is always disrupted because of annual flood. The government spent lots of effort to reduce the flood, but the flood is still happening. On the other hand, as one of important industrial areas in East Java, Gresik Regency should be floodfree. In this final project, the planned flood discharge is known by hydrologic analysis of daily rainfall data. In this analysis, the cycle period of planned flood discharge is 25 years. Then, the capacity of Lamong River is calculated using HEC-RAS. By comparing the capacity of Lamong River and the planned flood discharge, flooding spot of Lamong River could be known. To solve the problem, several alternatives are designed. The first alternative is using normalization on the river with the riverbed of 20 – 70 meters width. The second alternative is using normalization by 20 – 40 meters width and dredging that designed based on the planned slope of riverbed. The third alternative has similar criteria to the second alternative with addition of embankment which maximum height is 3 meters. The fourth is designed like the third alternative, but there is no limitation for the maximum height of embankment. Then those four alternatives would be analyzed to know the capacity of Lamong river when the planned flood discharge is flowing. Based on analysis result of those four alternatives, it can be concluded that the fourth alternative is the best. It is so because the flood does not occured anymore in the Lamong River after the fourth alternative applied. In the fourth alternative at KM 4,6 was designed an addition of embankment’s height is 5 meters off the riverbank existing elevation or 6,76 meters from the riverbed elevation. So, the peak elevation of the embankment is +3,04 meter. Beside of increasing embankment’s height, normalization is designed by 20 meters width on KM 38 – KM 22,9; 25 meters on KM 22,8 – KM 18,8; 30 meters on KM 18,7 – KM 10,2; 35 meters on KM 10,1 – KM 1,9; and 40 meters on KM 1,8 – KM 0.

Item Type: Thesis (Undergraduate)
Additional Information: RSS 627.4 Pra s
Uncontrolled Keywords: Pengendalian Banjir, Kali Lamong, Tanggul, Normalisasi
Subjects: H Social Sciences > HN Social history and conditions. Social problems. Social reform
T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Faculty of Civil Engineering and Planning > Civil Engineering > (S1) Undergraduate Theses
Depositing User: Dian Arief Pramudya Pratomo
Date Deposited: 02 Feb 2018 02:21
Last Modified: 02 Feb 2018 02:21
URI: http://repository.its.ac.id/id/eprint/46402

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