Efek Angkutan Sedimen Bed-Load terhadap Hambatan Aliran di Sungai Baturusa Pulau Bangka
DOI:
https://doi.org/10.5614/jts.2021.28.1.5Keywords:
Hambatan Aliran, Koefisien kekasaran, Manning, Sungai BaturusaAbstract
AbstrakAngkutan sedimen pada sungai alami tentunya memberikan dampak terhadap karakteristik pengalirannya. dampak adanya proses transpor sedimen tentu akan berpengaruh terhadap debit aliran yang terjadi di sungai. Debit aliran dipengaruhi terhadap parameter hidraulik, kemiringan dan nilai hambatan yaitu kekasaran dasar sungai. Adapun tujuan yang ingin dicapai dari studi ini adalah menganalisa efek material angkutan sedimen bed-load terhadap hambatan aliran atau koefisien kekasaran. Penelitian ini dilakukan di 10 (sepuluh) cross section pada Sungai Baturusa dengan pengambilan sampel bed-load di dasar sungai dan dilakukan pengujian gradasi ukuran butiran partikel sampel material bed-load sedangkan parameter kecepatan aliran diukur menggunakan Propeller Currentmeter dan diukur juga dengan metode pelampung dalam pengukuran kecepatan permukaan dengan faktor koreksi 0,85. Hasil analisis koefisien hambatan dengan angkutan sedimen (bed-load) menunjukkan nilai koefisien hambatan lebih besar dibandingkan tanpa angkutan sedimen (no bed-load), angkutan sedimen yang terjadi di Sungai Baturusa akan mempengaruhi nilai koefisien hambatan aliran. Sedangkan analisa debit aliran berdasarkan koefisien Manning yang digunakan beberapa metode semuanya memberikan selisih debit yang sangat besar terhadap debit terukur, penentuan nilai Manning memiliki pengaruh yang cukup besar dalam estimasi kecepatan aliran dan debit aliran., selain itu kecepatan aliran, pengaruh Fr dan U/U* juga memiliki pengaruh terhadap nilai koefisien kekasaran pada Sungai Baturusa.
Kata-kata Kunci: Hambatan aliran, koefisien kekasaran, manning, sungai Baturusa
AbstractSediment transport in natural rivers certainly has an impact on their flow characteristics. The impact of the sediment transport process will certainly affect the flow rate that occurs in the river. Discharge effected hydraulic parameters, slope and resistance coefficient, namely river bed roughness. The objective of this study is to analyze the effect of the bed-load on the flow resistance or roughness coefficient. This research was conducted in 10 (ten) cross sections on the Baturusa River by taking bed-load samples on the river bed and testing the grading of the particle size of the bed-load material samples while the velocity parameters were measured using the Propeller Currentmeter and also measured by the float method in measurement. surface velocity with a correction factor of 0.85. The results of the drag coefficient analysis with sediment transport (bed-load) show the value of the drag coefficient is greater than without sediment transport (no bed-load), sediment transport that occurs on the Baturusa River will affect the value of the flow resistance coefficient. While the flow analysis based on the Manning coefficient used several methods, all of which provide a very large difference in discharge to the measured discharge, the determination of the Manning value has a large enough influence on the estimation of velocity and flow rate, besides velocity, the effect of Fr and U/U* also has an influence on the roughness coefficient value on the Baturusa River.
Keywords: Flow resistance, roughness coefficient, manning, Baturusa river
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