ANALISIS PENGENDALIAN SEDIMENTASI MUARA SUNGAI BANJIR KANAL BARAT KOTA SEMARANG

Abstract

Abstrak: Muara Sungai Banjir Kanal Barat mempunyai morfologi melebar ke daerah hilirnya sehingga kecepatan aliran sungai kecil yang berpotensi menimbulkan sedimentasi di muara. Selain itu adanya pasang surut dari air laut yang mengakibatkan sedimen di muara tidak bisa terbawa arus sungai ke laut bahkan kembali ke muara sungai oleh adanya backwater. Berdasarkan perhitungan transpor sedimen sejajar pantai dengan menggunakan metode fluks energi diperoleh sedimen sejajar pantai sebesar 591.017,140 m3/thn, sedangkan untuk angkutan sedimen dari sungai menggunakan persamaan Engelund&Hansen sebesar 127.952,470 m3/th. Volume budget sedimen diperoleh sebesar 718.969,610 m3/th. Berdasarkan perbandingan prisma pasang surut dan angkutan sedimen total (budget sedimen) P/Mnetto didapatkan nilaiS = 6,320 berdasarkan nilai tersebut maka muara sungai Banjir Kanal Barat memiliki mulut sungai yang tidak stabil karena nilai S < 20 (Triatmodjo, 2012).Sistem penangan yang baik untuk mengatasi masalah sedimentasi di muara sungai Banjir Kanal Barat adalah pengelolaan mulut sungai yang selalu terbuka dengan membuat jetty panjang di kedua sisi muara dengan panjang 1080,45 meter di sebelah kiri dan 646,06 meter di sebelah kanan muara sungai. Kata Kunci : Muara sungai, Gelombang, Angkutan sedimen, Pantai, Jetty  Abstract: The Western Flood Canal estuary has a widening morphology towards downstream areas, so that the velocity of small streams can create sedimentation in the estuary. In addition, there are also seawater tides that results in sediment in the river estuary not being carried to the sea, instead returning to the estuary due to the presence of backwater. Based on calculations of coastline sediment transport using the energy flux method, the coastline sediment transport is 591.017,140 m3/yr., while river sediment trasport is determined by the Engelund and Hansen equation to be 127952.470 m3/yr. The sediment budget volume is        718.969,610 m3/yr. Based on the comparison between prism tides and total sediment transport (sediment budget) P/Mnetto, a value of S = 6,320 was obtained. Based on these values, the Western Flood Canal estuary has an unstable river mouth because S < 20 (Triatmodjo, 2012). A good handling system to overcome the problem of sedimentation in the Western Flood Canal estuary is the management of an always-open river mouth by the creation of a long jetty on both sides of the estuary with a length of 1080,45 meters on the left and 646,06 meters on the right. Keywords: estuary of river, wave, sediment transport, shore, Jetty