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Experimental Study of Energy Dissipation at Baffled Chute Spillway Joko Nugroho; Indratmo Soekarno; Agung Wiyono Hadi Soeharno
Jurnal Teknik Sipil Vol 26 No 1 (2019)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2019.26.1.5

Abstract

Experimental observation on a model of free over flow spillway is used in this study.  Three configurations of baffle placement are used in the experiment.  The energy along the flow over the spillway were calculated based on measured flow depth and discharge during the experiment. Variations of flow depth and discharge were determined based on baffle height as a reference.  The experiments were done in a 7 meters long flume of 0.078 m wide.  The spillway model has a dimension of 17.2 cm high, with rounded crest and 1:1 downstream slope.  There is no structures placed at the downstream of spillway.  The discharge applied to the spillway model is in the range of 0.6 to 1.8 l/s.  The experimental results shows that optimum results of energy dissipation were obtained when the flow depth is equal to the height of the baffle.  Observed energy dissipations in this is in the range of 30% to 50% upon the incoming energy of the spilled flow.  It was also observed that the length of the hydraulic jumped is reduced due to the application of baffled chute.Pengamatan eksperimental pada model pelimpah digunakan dalam penelitian ini. Tiga konfigurasi penempatan baffle digunakan dalam percobaan. Energi sepanjang aliran di atas spillway dihitung berdasarkan kedalaman aliran dan debit yang diukur selama percobaan. Variasi kedalaman aliran dan debit ditentukan berdasarkan tinggi baffle sebagai referensi. Percobaan dilakukan dalam flume 7 meter panjang lebar 0,078 m. Model spillway memiliki dimensi tinggi 17,2 cm, mercu bulat dan kemiringan hilir 1: 1. Tidak ada struktur yang ditempatkan di hilir spillway. Debit yang diterapkan pada model pelimpah berada dalam kisaran 0,6 hingga 1,8 l/s. Hasil eksperimen menunjukkan bahwa hasil optimal disipasi energi diperoleh ketika kedalaman aliran sama dengan ketinggian baffle. Disipasi energi yang diamati dalam penelitian ini adalah sekitar 30% sampai 50% pada energi yang masuk dari aliran yang melalui pelimpah. Dalam eksperimen diamati bahwa panjang loncatan hidrolik berkurang karena penerapan baffle pada saluran peluncur. 
UJI MODEL FISIK PENGENDALIAN ELEVASI DASAR SUNGAI DI SEKITAR INTAKE POLDER ALABIO, KABUPATEN HULU SUNGAI UTARA, PROPINSI KALIMANTAN TIMUR DENGAN MENGGUNAKAN VANE Joko Nugroho; Febry Asthia Miranti; Yiniarti Eka Kumala; Dhemi Harlan
Jurnal Teknik Sipil Vol 28 No 2 (2021): Jurnal Teknik Sipil
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2021.28.2.4

Abstract

Abstrak Pada makalah ini disampaikan hasil penelitian terhadap pengendalian elevasi dasar sungai di depan intake dengan menggunakan vane, pada kasus intake Irigasi Polder Alabio, Kabupaten Hulu Sungai Utara, Provinsi Kalimantan Selatan, dengan menggunakan model fisik. Intake dari daerah irigasi ini berada di Sungai Negara.  Lahan pada DAS Sungai Negara semakin kritis sehingga terjadi pendangkalan dasar sungai, sehingga hal ini dapat mengganggu kinerja operasional intake irigasi teknis. Pemodelan fisik di laboratorium dilakukan dengan menggunakan skala geometri 1:40, dengan kala kecepatan dan debit ditentukan berdasarkan keserupaan aliran berdasarkan bilangan Froude. Model vane yang digunakan di laboratorium berukuran panjang 10 cm, tebal 1 cm, tinggi 3 cm. Pengujian dilakukan dengan debit prototip 263,17 m3/s dan 65,53 m3/s. Berdasarkan hasil percobaan didapatkan bahwa pemasangan vane dapat menurunkan elevasi dasar sungai di depan intake. Kemapuan vane dalam menurunkan elevasi dasar sungai dipengaruhi oleh jarak terhadap intake dalam arah lateral maupun longitudinal. Dari simulasi pada model fisik, perbandingan volume sedimen yang masuk akibat vane terhadap volume sedimen eksisting dapat diturunkan hingga 44%. Kata kunci: Vane, intake, gerusan, sedimentasi. Abstract This paper presents the results of research through a physical model on controlling the elevation of the riverbed in front of the intake using a vane, in the case of the Alabio Polder Irrigation intake, North Hulu Sungai Regency, South Kalimantan Province. The intake of this irrigated area is located at Sungai Negara. The land in the Sungai Negara watershed is increasingly critical in terms of land cover, resulting in silting of the riverbed, so that this can interfere with the operational performance of irrigation intake. Physical modeling in the laboratory was carried out using a geometric scale of 1:40, with the velocity and discharge at the model are determined based on the similarity based on the Froude number.  The vane model used in the laboratory was 10 cm long, 1 cm thick, and 3 cm high. The test was carried out with prototype discharges of 263.17 m3/s and 65.53 m3/s. Based on the experimental results, it was found that the installation of vanes can reduce the elevation of the riverbed in front of the intake. The vane's ability to reduce the riverbed elevation is affected by the distance to the intake in both lateral and longitudinal directions. From the simulation on the physical model, the ratio of the incoming sediment volume due to the vane to the existing sediment volume can be reduced to 44%. Kata kunci: Vane, intake, scour, sedimentation. Abstrak Pada makalah ini disampaikan hasil penelitian terhadap pengendalian elevasi dasar sungai di depan intake dengan menggunakan vane, pada kasus intake Irigasi Polder Alabio, Kabupaten Hulu Sungai Utara, Provinsi Kalimantan Selatan, dengan menggunakan model fisik. Intake dari daerah irigasi ini berada di Sungai Negara.  Lahan pada DAS Sungai Negara semakin kritis sehingga terjadi pendangkalan dasar sungai, sehingga hal ini dapat mengganggu kinerja operasional intake irigasi teknis. Pemodelan fisik di laboratorium dilakukan dengan menggunakan skala geometri 1:40, dengan kala kecepatan dan debit ditentukan berdasarkan keserupaan aliran berdasarkan bilangan Froude. Model vane yang digunakan di laboratorium berukuran panjang 10 cm, tebal 1 cm, tinggi 3 cm. Pengujian dilakukan dengan debit prototip 263,17 m3/s dan 65,53 m3/s. Berdasarkan hasil percobaan didapatkan bahwa pemasangan vane dapat menurunkan elevasi dasar sungai di depan intake. Kemapuan vane dalam menurunkan elevasi dasar sungai dipengaruhi oleh jarak terhadap intake dalam arah lateral maupun longitudinal. Dari simulasi pada model fisik, perbandingan volume sedimen yang masuk akibat vane terhadap volume sedimen eksisting dapat diturunkan hingga 44%. Kata kunci: Vane, intake, gerusan, sedimentasi. Abstract This paper presents the results of research through a physical model on controlling the elevation of the riverbed in front of the intake using a vane, in the case of the Alabio Polder Irrigation intake, North Hulu Sungai Regency, South Kalimantan Province. The intake of this irrigated area is located at Sungai Negara. The land in the Sungai Negara watershed is increasingly critical in terms of land cover, resulting in silting of the riverbed, so that this can interfere with the operational performance of irrigation intake. Physical modeling in the laboratory was carried out using a geometric scale of 1:40, with the velocity and discharge at the model are determined based on the similarity based on the Froude number.  The vane model used in the laboratory was 10 cm long, 1 cm thick, and 3 cm high. The test was carried out with prototype discharges of 263.17 m3/s and 65.53 m3/s. Based on the experimental results, it was found that the installation of vanes can reduce the elevation of the riverbed in front of the intake. The vane's ability to reduce the riverbed elevation is affected by the distance to the intake in both lateral and longitudinal directions. From the simulation on the physical model, the ratio of the incoming sediment volume due to the vane to the existing sediment volume can be reduced to 44%. Kata kunci: Vane, intake, scour, sedimentation.  
ANALISIS PRIORITAS PENANGANAN BANJIR KALI KONTO, PROVINSI JAWA TIMUR Dian Indrawati; Mohammad Bagus Adityawan; Diki Maulana Ichsan; Dhemi Harlan; Joko Nugroho
Rekayasa Sipil Vol. 16 No. 3 (2022): Rekayasa Sipil Vol.16. No.3
Publisher : Department of Civil Engineering, Faculty of Engineering, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.rekayasasipil.2022.016.03.4

Abstract

Flood in Kali Konto is a disastrous hazard which strikes a lot of housing, infrastructures and paddy fields along its river banks almost every year. In 2021, along with destroyed revertment at roolagh 70 area, flood inundated more than 10 villages in Kabupaten Jombang and several more in Malang and Kediri. However, flood management at Kali Konto needs special consideration because several conditions, include watershed area pattern, extremely slope condition changing, numerous materials from Kelud mountain eruption in several part of Konto river, and a lot of infrastructures which laid in Konto river. This paper discussed about appropriate infrastructures which derived from hydrology and hydraulics modeling for Q2 and Q50 flood return periods. Since the model resulted 49 locations, Analytical Hierarchy Process (AHP) model used for determining priority for scaling down flood hazard in Kali Konto. The most priority comes to Karang Tengah, Blaru and Bugasur Kedaleman area based on the most losses occurred.
Laboratory Experiments on Mechanisms of Movement of Volcanic Materials at Various Slopes, Rain Intensity, and Thickness of Volcanic Ash F. Tata Yunita; Indratmo Soekarno; Joko Nugroho; Untung Budi Santosa
Jurnal Teknik Sumber Daya Air Desember 2022
Publisher : Himpunan Ahli Teknik Hidraulik Indonesia (HATHI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56860/jtsda.v3i1.48

Abstract

Perubahan iklim berdampak pada peningkatan intensitas dan frekuensi cuaca ekstrim dan menyebabkan potensi kejadian banjir lahar pasca erupsi semakin tinggi. Fokus penelitian terkait banjir lahar umumnya lebih mengamati fenomena banjir yang terjadi di alur sungai, sementara penelitian terkait mekanisme gerakan material vulkanik di lereng masih sangat terbatas. Pengamatan proses pembentukan aliran lahar di lereng puncak menjadi tantangan karena kondisi medan yang sulit dan berbahaya. Oleh karena itu, dalam penelitian ini observasi dan pengukuran mekanisme gerakan material vulkanik lereng dilakukan dengan eksperimental model fisik skala laboratorium. Eksperimen berupa demonstrasi plot (demplot) lereng yang tertutup material vulkanik (abu vulkanik gradasi <2 mm) dilakukan dalam 36 set percobaan dengan beberapa variasi kemiringan lereng (80, 150, 200, 250), intensitas hujan (45-120 mm/jam) dan ketebalan abu vulkanik (0 cm, 1 cm, 2,5 cm, 5 cm), dimana durasi percobaan maksimal 2 jam. Hasil penelitian ini menunjukkan bahwa mekanisme pergerakan material vulkanik di lereng terjadi dalam 2 mekanisme, yaitu longsor dan erosi. Mekanisme longsor terjadi secara rotasional pada intensitas hujan antara 55-80 mm/jam, dimana pergerakan material dipicu oleh terganggunya stabilitas lereng akibat erosi di kaki lereng dan/atau meningkatnya tegangan air pori dan bobot lapisan tanah akibat infiltrasi. Mekanisme erosi diawali dengan terbentuknya galur-galur akibat adanya aliran permukaan setelah lapisan abu vulkanik di permukaan lereng jenuh, dimana intensitas hujan pemicu umumnya >80 mm/jam. Longsor tidak terjadi pada kemiringan lereng 80, sedangkan erosi dapat terjadi pada semua variasi kemiringan lereng. Lapisan abu vulkanik terbukti menghambat infiltrasi sehingga meningkatkan potensi terjadinya aliran permukaan dan erosi.
PEMODELAN SEDIMENTASI MENGGUNAKAN HEC-RAS 6.1 UNTUK MENGANALISIS PERUBAHAN ELEVASI DASAR SUNGAI TONDANO, SULAWESI UTARA Muhammad Taufiq Makmur Zainuddin; Irmanto Irmanto; Joko Nugroho; Waluyo Hatmoko
JURNAL TEKNIK HIDRAULIK Vol 14, No 1 (2023): JURNAL TEKNIK HIDRAULIK
Publisher : Pusat Litbang Sumber Daya Air, Kementerian Pekerjaan Umum dan Perumahan Rakyat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32679/jth.v14i1.721

Abstract

ABSTRACT Sedimentation is a problem that can cause siltation and changes in river morphology due to reduced river capacity and increased runoff. The Tondano River is one of the major rivers that cross the City of Manado, which has a significant contribution in terms of the impact of flooding and, in its current conditions, has experienced considerable siltation so that the capacity of the river is unable to carry discharge. This study aims to analyze the changes in the elevation of the Tondano River bed that occurred within 6 years from 2016 to 2022 due to sedimentation. Sedimentation modelling is done using the HEC-RAS 6.1 application because, it has new features and improvements over the previous version, especially for, sediment transport analysis using the Meyer Peter Muller empirical equation. The bathymetric data used is the 2016 measurement, and a sediment model simulation is carried out for a 6-year daily discharge period. Then verification is carried out with the 2022 bathymetry data and current field conditions. The results show that the Tondano River on the Kairagi section, along 7.20 km from the estuary, experienced a significant change in riverbed elevation due to sedimentation. There was an average aggradation or sedimentation thickness of 0.891 m for 6 years and an estimated 0.130 to 0.140 m per year, so under these conditions, the cross-section of the Tondano River experienced siltation and reduced the capacity of the river to carry flood discharge. The simulation results showed that changes in river bed elevation also cause an increase in water level as high as 1 to. 2 m. From the simulation results of changes in the bottom of the Tondano River section of Kairagi, a total sedimentation amount of 83,087.49 m3 for 6 years was obtained.Keywords: sedimentation, river bed elevation, water surface elevation, aggradation, deposition ABSTRAKSedimentasi merupakan permasalahan yang dapat menyebabkan terjadinya pendangkalan dan perubahan morfologi sungai karena berkurangnya kapasitas sungai sehingga terjadi peningkatan aliran permukaan. Sungai Tondano adalah salah satu sungai besar yang melintas di Kota Manado yang menjadi salah satu sungai yang memiliki kontribusi besar dalam hal dampak banjir dan pada kondisi saat ini telah mengalami pendangkalan yang signifikan sehingga kapasitas sungai tidak mampu dalam mengalirkan debit. Tujuan penelitian ini yaitu untuk menganalisis perubahan elevasi dasar Sungai Tondano yang terjadi dalam kurun waktu 6 tahun dari tahun 2016 hingga 2022 akibat sedimentasi. Pemodelan sedimentasi dilakukan menggunakan aplikasi HEC-RAS 6.1 karena pada versi ini terdapat beberapa fitur baru dan perbaikan dari versi sebelumnya, yaitu persamaan angkutan sedimen menggunakan persamaan empiris Meyer Peter Muller. Data batimetri yang digunakan adalah pengukuran tahun 2016 dan dilakukan simulasi model sedimen selama periode debit harian 6 tahun kemudian dilakukan verifikasi dengan data batimetri tahun 2022 serta kondisi lapangan saat ini. Hasilnya dapat disimpulkan bahwa Sungai Tondano pada ruas Kairagi sepanjang 7,20 km dari muara mengalami perubahan elevasi dasar sungai yang cukup signifikan akibat sedimentasi. Terjadi agradasi atau tebal sedimentasi rata-rata sebesar 0,891 m selama 6 tahun dan diperkirakan sebesar 0,130 s.d 0,140 m per tahun, sehingga dengan kondisi tersebut penampang Sungai Tondano mengalami pendangkalan dan menyebabkan berkurangnya kapasitas sungai dalam mengalirkan debit banjir. Hasil simulasi perubahan elevasi dasar sungai tersebut juga menunjukkan terjadinya kenaikan elevasi muka air setinggi 1 s.d. 2 m. Dari hasil simulasi perubahan dasar Sungai Tondano ruas Kairagi diperoleh total besaran sedimentasi sebesar 83.087,49 m3 selama 6 tahun. Kata Kunci: sedimentasi, elevasi dasar sungai, elevasi muka air, agradasi, pengendapan
Evaluation of Drainage System of Light Rapid Transport (LRT) Depo – Kelapa Gading – Jakarta City Joko Nugroho; Mohammad Bagus Adityawan; Ana Nurganah Chaidar; Yadi Suryadi
Journal of Engineering and Technological Sciences Vol. 55 No. 5 (2023)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2023.55.5.9

Abstract

LRT Depo is a vital infrastructure in the operation of Jakarta’s LRT system. The LRT Depo is located in the Kelapa Gading area. Kelapa Gading is an inundation-prone area in Jakarta. Hence a drainage system should be prepared to manage surface runoff in the area to avoid additional runoff to the surrounding drainage system. In order to reduce runoff in Jakarta Special Province, the Governor of Jakarta has imposed a regulation on surface runoff management for every developed area. The runoff control measures, promoted in the regulation to be applied, are in the form of infiltration wells and storage ponds. The principle of reducing peak discharge by a possible storage system for LRT Depo was designed and applied to comply with regional regulations on rainwater control. The drainage system, initially based on the regulations, was also modeled in the Storm Water Management Modelling software (SWMM). This study evaluated the drainage system by elaborating the reduction of the peak discharge based on the simulation. A reduction of peak discharge was observed in the modeling results. The proposed runoff control at LRT Depo Kelapa Gading is a proper design of infrastructure development for a flood prone area.