Shiami, Faradilla Ayu Rizki (2017) Prediksi Laju Sedimentasi pada Tampungan Bendungan Tugu Trenggalek. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
Preview |
Text
3113100090-Undergraduated_Thesis.pdf - Published Version Download (7MB) | Preview |
Abstract
Hal terpenting dalam perencanaan waduk selain desain hidrolis bendungan adalah sedimentasi. Sedimen yang mengendap di waduk merupakan faktor pembatas kapasitas tampungan efektif waduk, sehingga jumlah sedimen di waduk biasa digunakan untuk menetapkan masa guna waduk. Prediksi sedimentasi yang terjadi pada waduk dilakukan dengan memperhitungkan besar laju sedimentasi berdasarkan metode perhitungan analitik, namun untuk mempermudah dalam menggambarkan sedimentasi yang terjadi pada waduk dilakukan metode pemodelan menggunakan software HEC-RAS. Program HEC-RAS sendiri merupakan salah satu program pemodelan analisis angkutan sedimen pada saluran maupun sungai. Tujuannya adalah untuk memprediksi besar laju sedimentasi pada Waduk Tugu dengan metode perhitungan analitik dan pemodelan software HEC-RAS, kemudian kedua hasilnya dibandingkan.
Pada perhitungan maupun pemodelan sedimentasi menggunakan HEC-RAS data yang dibutuhkan adalah data geometri sungai, data hidrolika, debit sungai, dan parameter sedimen. Pemodelan sedimentasi dengan HEC-RAS dilakukan dengan mencoba beberapa model. Pemodelan pertama berupa sungai dan tubuh bendung. Pemodelan kedua dengan penambahan ambang pelimpah. Pemodelan ketiga, sungai yang dimodelkan hanya alur sungai bagian hilir. Pemodelan keempat penambahan culvert sebagai saluran pengambilan. Pemodelan kelima dengan menambah lateral inflow pada hulu tubuh bendung sebagai alternatif lain untuk memodelkan saluran pengambilan. Pemodelan keenam sama dengan pemodelan keempat namun dengan debit inflow pertama yang dibesarkan sebagai asumsi bahwa waduk terisi penuh baru dioperasikan. Perhitungan analitik dihitung dengan metode total load Laursen yang juga digunakan dalam pemodelan HEC-RAS dan dihitung pada penampang melintang bagian hulu.
Hasil perhitungan analitik berupa besar angkutan sedimen yang kemudian dibandingkan dengan pemodelan HEC-RAS. Angkutan sedimen hasil dari perhitungan analitik cenderung lebih kecil daripada hasil dari pemodelan HEC-RAS, dimana perkiraan besar laju sedimentasi dari metode pemodelan HEC-RAS sebesar 22.000 m3/th sedangkan laju sedimentasi hasil perhitungan analitik sebesar 19.400 m3/th. hal ini dikarenakan penyederhanaan geometri penampang pada perhitungan analitik, sedangkan geometri pada model lebih detail.
========================================================================================================================
In dam’s design, one of the most important things to be aware is not only the hydraulic design but also the sedimentation. Sediments that settle in the reservoirs are one of the limiting factors for the effective storage capacity of the reservoir, so that the amount of sediment in the reservoir is commonly used to calculate the reservoir’s period. Sedimentation that occurs at the dam’s reservoir is predicted by calculate the amount of sedimentation rate based on analytical calculation method, but to make it easier to describe sedimentation that happened in reservoir, is by using HEC-RAS software modeling. HEC-RAS program is a modeling program for the analysis of sediment transport on channels and rivers. The purpose is to predict the sedimentation rate at Tugu’s Reservoir with analytical calculation method and HEC-RAS software modeling, then the two results are compared.
In the calculation and modeling of sedimentation using HEC-RAS data that needed are river geometry data, hydraulic data, river inflow, and sediment parameters. Sedimentation modeling with HEC-RAS is done by trying several models. The first modeling is river and main dam. Second modeling with the addition of the overflow threshold. Third modeling, the river is modeled only downstream river channel. The fourth model of adding culvert as a retrieval channel. The fifth modeling by adding lateral inflow on the upstream of the main dam as another alternative to modeling the retrieval channel. The sixth model is the same as the fourth model but with the first inflow raised as an assumption that the reservoir fully charged before the reservoir is operated. Analytical calculations were calculated by the Laursen total load method, which is also used in HEC-RAS modeling and calculated on the upstream cross section.
The output of analytical calculations are the amount of sediment transport which is compared with the output of HEC-RAS modeling. Sediment transport load result from analytical calculation tends to be smaller than result of HEC-RAS modeling, where sedimentation rate estimation from HEC-RAS modeling method is 21,000 m3/year while sedimentation rate of analytical calculation result is 19,400 m3/year. This is due to the simplification of the cross section geometry of the analytic calculation, while the geometry of the model is more detailed.
Key word : analytical calculation, HEC-RAS program, reservoir, sedimentation.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | analytical calculation, HEC-RAS program, reservoir, sedimentation. |
| Subjects: | Q Science > QE Geology > QE571 Sedimentation and deposition. Sediment transport. Erosion. T Technology > TA Engineering (General). Civil engineering (General) |
| Divisions: | Faculty of Civil Engineering and Planning > Civil Engineering > 22201-(S1) Undergraduate Thesis |
| Depositing User: | Faradilla Ayu Rizki Shiami |
| Date Deposited: | 27 Sep 2017 04:07 |
| Last Modified: | 06 Mar 2019 03:51 |
| URI: | http://repository.its.ac.id/id/eprint/44200 |
Actions (login required)
 |
View Item |