Eka, Juli Dwi Mulyawati and Dr. Ir. Very Dermawan, ST., MT., IPM and Dr. Eng. Evi Nur Cahya, ST., MT (2023) Studi Pola Gerusan di Hilir Bendung Alale Kabupaten Bone Bolango, Provinsi Gorontalo. Sarjana thesis, Universitas Brawijaya.
Abstract
Bendung Alale merupakan salah satu bendung yang dibangun untuk memenuhi kebutuhan air irigasi di Daerah Irigasi (DI) Lomaya Alale Kabupaten Bone Bolango Provinsi Gorontalo. Namun bendung ini perlu direhabilitasi dikarenakan terjadi overtopping di dinding penahan sehingga menimbulkan banjir di daerah sekitar. Supaya proses rehabilitasi bendung tepat dan optimal maka diperlukan uji model fisik. Salah satu parameter yang diuji di model adalah gerusan lokal. Studi ini bertujuan untuk mengetahui pola gerusan pada kondisi awal (Seri 0), rekomendasi penanggulangan, dan perbedaan pola gerusan pada kondisi awal (Seri 0) dengan kondisi setelah perubahan (Seri 3) beserta perhitungan secara empiris. Pelaksanaan uji model fisik Bendung Alale dilakukan di Laboratorium Hidrolika Terapan Departemen Teknik Pengairan, Fakultas Teknik, Universitas Bawijaya dengan menggunakan fasilitas yang telah disediakan. Pengujian model harus memenuhi syaratsyarat kesebangunan supaya hasil yang akan diperoleh sesuai dengan kondisi di lapangan (prototype). Oleh dari itu, sebelum model digunakan, perlu dilakukan kalibrasi dan verifikasi model. Apabila hasil kalibrasi dan verifikasi sudah sesuai dengan kaidah hidrolika, maka pengukuran model dengan debit rencana Q2th, Q5th, Q10th, Q25th,Q50th, dan Q100th. Untuk mempermudah pengukuran dan pengamatan maka model dibagi menjai beberapa sections sehingga data yang diperoleh memiliki ketelitian yang optimum. Adapun parameter-parameter yang diamati dan diukur adalah tinggi muka air, kecepatan aliran, tekanan dan gerusan lokal. Gerusan lokal dapat disebabkan oleh loncatan hidrolik dan kehilangan energi apabila dasar saluran berupa granular Untuk meminimalkan gerusan biasanya menggunakan kolam olak, rip-rap, endsill atau kombinasi dari itu. Penambahan lantai blok beton di hilir kolam olak juga dapat digunakan untuk meminimalkan gerusan akibat peredaman energi yang bertahap. Pada studi ini, penelitian gerusan di hilir Bendung Alale tanpa menggunakan lantai blok beton akan dibandingkan dengan gerusan di hilir bendung dengan menggunakan lantai blok beton yang dilaksanakan di Laboratorium Hidrolika Terapan. Selain itu, kedalaman gerusan juga dihitung menggunakan 3 (tiga) metode empiris yang kemudian dibandingkan dengan hasil pengamatan. Hasil percobaan menunjukkan gerusan berkurang dengan penambahan lantai blok beton di hilir kolam olak dengan gerusan terdalam semula pada elevasi +22,80 menjadi +25,10. Sedangkan metode empiris yang memiliki hasil mendekati dengan hasil pengamatan adalah Metode Vendijh dengan KR sebesar 37,64% dan Metode USBR dengan KR sebesar 42,27%
English Abstract
Alale Weir is one of the weirs that was constructed to supply the water for the irrigation system to Lomaya Alale Irrigation Area, Bone Bolango Regency, Gorontalo Province. However, this weir needs to be rehabilitated due to overtopping of the retaining wall which causes flooding in the surrounding area. For the weir rehabilitation process to be appropriate and optimal, it is necessary to test by a physical model. One of the parameters that was tested is local scour. This study aims to determine the sour pattern in the initial condition (Series 0) recommendations for the countermeasures, and the differences in scour pattern in the initial conditions (Series 0) and the conditions after the change (Series 3) along with empirical calculations. The Alale Weir physical model test was simulated at the Applied Hydraulics Laboratory of the Department of Water Resources Engineering, Faculty of Engineering, Brawijaya University using facilities of similarity so that the results to be obtained are by the conditions in the field (prototype). Therefore, before the is used, it is necessary to calibrate and verify the model. if the calibration and verification results are following hydraulics principles, then the measurement model with the planned discharge Q2th, Q5th, Q10th, Q25th, Q50th, and Q100th. To facilitate measurement and observation the model is divided into several sections so that the data obtained has optimum accuracy. The parameters observed and measured were water level, flow velocity, pressure and local scour. Local scour can be caused by hydraulic jumps and energy loss if the channel bed is granular. To minimize scour, stilling basins, riprap, end sills or a combination of these are usually used. The addition of a concrete block floor downstream of the stilling basin can also be used to minimize scour due to gradual energy dissipation. In this study, research on scouring downstream of the Alale Weir without using a concrete block floor will be compared to scouring downstream of the weir using a concrete block floor which was carried out at the Applied Hydraulics Laboratory. In addition, the scour depth was also calculated using 3 (three) empirical methods which were then compared with the observed results. The experimental results indicate that scour decreased with the addition of a concrete block floor downstream of the stilling basin with the deepest scour originally at an elevation of +22.80 to +25.10. And the empirical method which has results close to the observation is the Vendijh Method with a RE of 37.64% and the USBR Method with a RE of 42.27%.
| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | 052307 |
| Uncontrolled Keywords: | Gerusan lokal, Bendung, Uji model - Local Scouring, Weir, Model test |
| Divisions: | Fakultas Teknik > Teknik Pengairan |
| Depositing User: | Unnamed user with username pratiwi |
| Date Deposited: | 12 Jan 2024 02:32 |
| Last Modified: | 12 Jan 2024 02:32 |
| URI: | http://repository.ub.ac.id/id/eprint/208845 |
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