Perencanaan Normalisasi Sungai Rawaan Bagian Hilir Kecamatan Tempursari Kabupaten Lumajang

Nugraha, Willy Lucyta (2019) Perencanaan Normalisasi Sungai Rawaan Bagian Hilir Kecamatan Tempursari Kabupaten Lumajang. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sungai Rawaan adalah sungai yang terletak di Desa Bulurejo, Kecamatan Tempursari, Kabupaten Lumajang. Sungai Rawaan merupakan sungai yang bermuara ke Pantai TPI. Sungai Rawaan memiliki panjang sungai ±15,175 km dan luas DAS ± 64,40 km2. Pada bagian hilir Sungai Rawaan yang bermuara ke Pantai TPI, seringkali terjadi banjir. Banjir diakibatkan dari banyaknya sedimen di Pantai TPI yang menutupi muara Sungai Rawaan dan sedimen yang ada pada Sungai Rawaan itu sendiri. Selain sedimen, curah hujan yang cukup tinggi juga turut menjadi sebab terjadinya banjir di wilayah tersebut. Sehingga kapasitas penampang eksisting sungai tidak mampu menampung debit yang masuk ke sungai. Sehubungan dengan permasalahan di atas, perlu adanya penanganan guna mengatasi luapan tersebut yaitu dengan cara menormalisasi Sungai Rawaan bagian hilir. Dalam menormalisasi Sungai Rawaan, diperlukan analisis hidrologi dan analisis hidrolika. Analisis hidrologi dilakukan dari data curah hujan selama 10 tahun yang kemudian diproyeksikan menjadi curah hujan rencana periode ulang 25 tahun untuk menghitung debit banjir rencana periode ulang Q25 dengan metode hidrograf Nakayasu. Analisis hidrolika dilakukan dengan program bantu HEC-RAS untuk mengetahui kapasitas penampang eksisting dan desain penampang sungai agar mampu mengalirkan debit banjir rencana periode ulang. Berdasarkan perhitungan hidrograf banjir dengan metode Nakayasu, didapatkan debit banjir rencana Q25 sebesar 298 m3/det. Dari hasil analisis dengan program bantu HEC-RAS, terjadi luapan pada beberapa titik segmen sungai, artinya penampang sungai eksisting tidak mampu mengalirkan debit banjir rencana periode ulang. Sehingga, diperlukan normalisasi sungai agar mampu mengalirkan debit banjir rencana. Normalisasi dilakukan dengan cara pengerukan dasar sungai, pelebaran sungai, dan pada beberapa titik diperlukan peninggian tebing sungai berupa tanggul dengan elevasi +3.80 m hingga pada elevasi +4.60 m.
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Rawaan River is a river located in Bulurejo Village, Tempursari District, Lumajang Regency. The river downstream to TPI Beach. The Rawaan River has a length of ± 15,175 km and a watershed area of ± 64.40 km2. In the river downstream, flooding often occurs. Floods are caused by the large amount of sediment in the TPI Beach which cover up the estuary of the Rawaan River and the sediments that exist on the Rawaan River. In addition to sediment, high rainfall is also a cause of flooding in the region. So that the existing cross-sectional capacity of the river cannot accommodate the discharge in the river. According to the problems, it is necessary to solve the problems with normalizing the downstream Rawaan River.
In normalizing the Rawaan River, hydrological analysis and hydraulic analysis are needed. Hydrological analysis from rainfall data, rain station data, watershed data, and land use data. This data is used to calculate the flood discharge with a 25 year return period (Q25). The rainfall data used is for 10 years, then it is projected to be a 25-year return period. From the return period rainfall, a flood hydrograph was made using the Nakayasu method. This hydrograph is then used for hydraulic analysis of river cross section designs with HEC-RAS programs. Hydraulics analysis from river cross section data, flood hydrograph, and sea tides. The data is used in hydraulic analysis by input it in the HEC-RAS program. Hydraulics analysis with HEC-RAS is to find out the existing river capacity and normalization design of river crossings to be able to drain off the flood discharge. In this plan, the river that will be normalized is the downstream of Rawaan River, with length 4091 m.
Based on the calculated flood hydrograph with Nakayasu method, the return period Q25 flood discharge is 298 m3/sec. From the results of the analysis with the HEC-RAS program, flooding occurred at several river segment points. It’s mean that the existing river cross section is unable to drain off the flood discharge. So, it is necessary to normalize the river in order to be able to drain off the flood discharge. Normalization can be done with dredging the riverbed, widening the river, and build dikes at some point the of the river. Dikes are built with +3.80 m elevation up to +4.60 m elevation.

Item Type: Thesis (Other)
Uncontrolled Keywords: Flood, Overflow, Normalization, Rawaan River, and HEC-RAS
Subjects: T Technology > T Technology (General) > T57.62 Simulation
T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics
T Technology > TC Hydraulic engineering. Ocean engineering > TC424 Water levels
T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions: Faculty of Civil, Environmental, and Geo Engineering > Civil Engineering > 22201-(S1) Undergraduate Theses
Depositing User: WILLY LUCYTA NUGRAHA
Date Deposited: 10 Jul 2024 02:05
Last Modified: 10 Jul 2024 02:05
URI: http://repository.its.ac.id/id/eprint/66554

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