PENGENDALIAN BANJIR PADA SUNGAI TAWING DI KABUPATEN TRENGGALEK

Yuniariski, Dellia (2025) PENGENDALIAN BANJIR PADA SUNGAI TAWING DI KABUPATEN TRENGGALEK. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sungai Tawing merupakan salah satu sungai besar di Kabupaten Trenggalek. Ketika hujan deras berlangsung di seluruh aliran DAS Tawing selama 6 jam, maka terjadilah banjir di sepanjang aliran Sungai Tawing. Faktor utama yang menyebabkan banjir ini terjadi adalah luasnya daerah tangkapan air, yang menghasilkan aliran tinggi selama musim hujan. Keadaan ini semakin buruk karena adanya pendangkalan sungai akibat pengendapan sedimentasi. Proyek akhir ini bertujuan untuk mengevaluasi kemampuan Sungai Tawing dalam mengalirkan debit banjir serta melakukan tindakan normalisasi sungai sebagai tindakan penanganan banjir yang akan dilaksanakan. Analisis dilakukan terhadap penampang eksisting dan penampang rencana menggunakan software HEC-RAS 2D. Pemodelan hidrologi menggunakan metode Hidrograf Satuan Sintetik Nakayasu untuk seluruh DAS sebagai input menuju Sungai Tawing. Simulasi dilakukan juga dengan mengatur pola operasi pintu dari Bendung Widoro sebagai bendung pengendali banjir. Pola operasi pintu ini dimodelkan sesuai dengan kondisi di lapangan berdasarkan data debit rilis dari Bendung Widoro di bagian hilir sungai. Berdasarkan pemodelan yang dilakukan terhadap kondisi eksisting, terjadi luapan dari sungai yang menyebabkan area persawahan dan pemukiman warga di sekitar sungai tergenangi. Dari permasalahan tersebut, dilakukan normalisasi dengan penampang sungai majemuk pada titik TW 141 hingga TW 127 dengan lebar dasar 35 meter, lebar atas 10 meter ke kiri dan 10 meter ke kanan dengan masing-masing kemiringan lereng 1:2, sesuai dengan debit rencana kala ulang 25, 50, dan 100 tahun. Jika melihat parameter luas genangan, normaliasi yang dilakukan dapat mereduksi genangan sebesar 43%, 39%, dan 38%.
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The Tawing River is one of the major rivers in Trenggalek Regency. When heavy rain continued throughout the Tawing watershed for 6 hours, flooding occurred along the Tawing River. The main factor causing this flood is the large catchment area, which results in high runoff during the rainy season. This situation is getting worse due to river siltation caused by sediment deposition. This final project aims to evaluate the ability of the Tawing River to discharge floodwater and to implement river normalization measures as a flood management strategy. The analysis was conducted on the existing cross-section and the planned cross-section using HEC-RAS 2D software. Hydrological modeling used the Nakayasu Synthetic Unit Hydrograph method for the entire watershed as input to the Tawing River. Simulations were also conducted by adjusting the gate operation patterns of the Widoro Dam, which serves as a flood control dam. These gate operation patterns were modeled according to field conditions based on the release discharge data from the Widoro Dam downstream. Based on modeling conducted on existing conditions, there was an overflow from the river causing the surrounding rice fields and residential areas to be flooded. From these problems, normalization was carried out using a composite river cross-section from point TW 141 to TW 127 with a base width of 35 meters, a top width of 10 meters to the left and 10 meters to the right, each with a slope of 1:2, in accordance with the design discharge for return periods of 25, 50, and 100 years. If we look at the parameters of the flooded area, the normalization carried out can reduce the flooding by 43%, 39%, and 38%.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Banjir, Normalisasi, Pengendalian Banjir, Sungai Tawing Flood, Flood Control, Normalization, Tawing River
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Dellia Yuniariski
Date Deposited:	04 Aug 2025 08:08
Last Modified:	04 Aug 2025 08:08
URI:	http://repository.its.ac.id/id/eprint/127029

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