Studi Pengendalian Banjir Sungai Wulan Di Kabupaten Demak dan Kudus Provinsi Jawa Tengah

Hannan, Firda Fadiyah Hannan (2025) Studi Pengendalian Banjir Sungai Wulan Di Kabupaten Demak dan Kudus Provinsi Jawa Tengah. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Banjir di Sungai Wulan selalu terjadi ketika musim hujan tiba. Banjir terjadi karena penampang Sungai Wulan tidak sanggup mengalirkan debit hujan. Sungai Wulan mengalir melalui Kabupaten Kudus dan Demak sebelum akhirnya bermuara ke laut. Sungai wulan menerima dari debit limpasan Pintu Air Wilalung sebesar 353,491 m3/dt dan tambahan debit dari sudetan Sungai Serang sendiri sebesar 63,298 m3/dt sementara kapasitas penampang Sungai Wulan sebesar 138,616 m3/dt. Kondisi ini menyebabkan Sungai Wulan selalu banjir ketika terjadi hujan. Melihat kondisi dan permasalahan yang terjadi maka perlu upaya penganggulangan banjir di Sungai Wulan. Analisis sebaran banjir menggunakan software HEC-RAS 2D. Perhitungan debit banjir rencana menggunakan metode Hidrograf Satuan Sintetik Nakayasu dengan kala ulang 25, 50, dan 100 tahun. Debit yang digunakan untuk pemodelan Sungai Wulan berasal dari debit rilis Bendung Klambu, sedangkan boundary hilir menggunakan pasang tertinggi yaitu 0,44 meter, dengan asumsi bahwa hujan terjadi bersamaan dengan pasang tertinggi. Hasil dari pemodelan HEC-RAS 2D pada STA 366 elevasi tanggul sungai setinggi +7,872 meter sedangkan elevasi muka air saat debit banjir kala ulang 25 tahun setinggi +8,526 meter, sehingga terjadi luapan di sepanjang bantaran sungai dengan luas genangan total sebesar 634,896 hektar. Pada kala ulang 50 tahun, elevasi muka air setinggi +8,544 dan menyebabkan luas genangan total 637,292 hektar. Sementara itu, kala ulang 100 tahun elevasi muka air setinggi +8,578 meter dengan luas genangan total sebesar 639,937 hektar. Dari hasil analisi tersebut, direncanakan penanganan banjir yaitu dengan normalisasi sungai. Perencanaan berbentuk penampang majemuk dengan lebar dasar 40 meter, lebar penampang berikutnya 15 meter ke kiri dan 15 meter ke kanan dengan kemiringan di setiap lerengnya 1:2 pada STA 366 hingga STA 432. Sehingga didapatkan luas genangan total pada debit banjir kala ulang 25, 50, dan 100 tahun berkurang menjadi 564,659 hektar, 570,532 hektar, dan 572,512 hektar. Peningkatan kapasitas saluran ini berdampak positif terhadap pengurangan luas genangan banjir, yang masing-masing berhasil direduksi sebesar 11,06%, 10,48%, dan 10,07%.
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Flooding in the Wulan River always occurs when the rainy season arrives. The flood occurred because the cross-section of the Wulan River was unable to drain the rain. The Wulan River flows through Kudus and Demak Regencies before finally emptying into the sea. The Wulan River receives from the runoff discharge of the Wilalung Water Gate of 353,491 m3/s and an additional discharge from the Serang River subsurface itself of 63,298 m3/s while the cross-sectional capacity of the Wulan River is 138,616 m3/s. This condition causes the Wulan River to always flood when it rains. Seeing the conditions and problems that occur, it is necessary to make efforts to prevent flooding in the Wulan River. Flood distribution analysis using HEC-RAS 2D software. The discharge used for modeling the Wulan River comes from the release discharge of the Klambu Dam, while the downstream boundary uses the highest tide of 0.44 meters, assuming that rain occurs at the same time as the highest tide. The results of HEC-RAS 2D modeling at STA 366 show that the elevation of the river embankment is +7,872 meters while the elevation of the water level during the 25-year flood discharge is +8,526 meters, so that there is an overflow along the riverbank with a total inundation area of 634,896 hectares. At the 50th anniversary, the water level was as high as +8.544 and caused a total inundation area of 637.292 hectares. Meanwhile, on the 100th anniversary of the water level elevation was +8,578 meters with a total inundation area of 639,937 hectares. From the results of the analysis, it is planned to handle floods, namely by normalizing the river. The plan is in the form of a compound cross-section with a base width of 40 meters, the width of the next cross-section is 15 meters to the left and 15 meters to the right with a slope on each slope of 1:2 on STA 366 to STA 432. So that the total inundation area in the flood discharge during the 25, 50, and 100 years was reduced to 564,659 hectares, 570,532 hectares, and 572,512 hectares. The increase in the capacity of this channel has a positive impact on reducing the area of flood inundation, which has been successfully reduced by 11.06%, 10.48%, and 10.07%, respectively.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Banjir, Sungai Wulan, HEC-RAS 2D, Normalisasi, Luas Genangan
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Firda Fadiyah Hannan
Date Deposited:	04 Aug 2025 03:46
Last Modified:	04 Aug 2025 03:46
URI:	http://repository.its.ac.id/id/eprint/126848

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