Kajian rencana pengendalian banjir Kali Beringin Kota Semarang

WIDODO, Irawan Insan, Prof.Dr.Ir. Budi Wignyosukarto, Dipl.HE

2007 | Tesis | S2 Teknik Sipil (Magister Pengelolaan Bencana Alam

Kali Beringin merupakan sungai yang secara periodik menyebabkan banjir di kawasan Mangkang, Kecamatan Tugu, Kota Semarang. Pekerjaan Desain Kali Beringin telah selesai dilaksanakan tahun 2003. Dalam desain tersebut, terdapat usulan pekerjaan normalisasi alur, pembangunan tanggul dan pembangunan jetty. Kajian hidraulik terhadap masing-masing jenis pekerjaan tersebut, dilakukan dengan pemodelan hidraulik menggunakan software Hydrologic Engineering Center-River Analysis System (HEC-RAS) Versi 3.1. Alur sungai diasumsikan sebagai alur tunggal dengan batas hulu penelitian pada HM 72+88 sampai ke HM 0 (muara). Input kondisi batas hulu berupa flow hydrograph dan kondisi batas hilir berupa stage hydrograph. Dalam kondisi eksisting, limpasan terjadi pada 22 River Station di kiri dan 27 River Station di kanan alur, kecepatan terbesar pada River Station 37, sebesar 3,63 m/dt. Dengan normalisasi alur, limpasan terjadi pada 22 River Station di kiri dan 27 River Station di kanan alur, kecepatan terbesar pada River Station 57 sebesar 4,74 m/dt. Dengan pembangunan tanggul, limpasan terjadi pada 12 River Station di kiri dan 13 River Station di kanan alur sungai, kecepatan terbesar pada River Station 37 sebesar 3,91 m/dt. Dengan pembangunan jetty, limpasan terjadi pada 22 River Station di kiri dan 30 River Station di kanan alur, kecepatan terbesar pada River Station 40, sebesar 3,69 m/dt. Setelah dilakukan kombinasi pekerjaan, dalam pembangunan tanggul dan normalisasi limpasan hanya terjadi pada 7 River Station. Prioritas urutan pelaksanaan pekerjaan akan lebih efektif secara hidraulik bila dimulai dari pembangunan tanggul, dilanjutkan normalisasi alur dan pembangunan jetty.

Beringin River is inducing flood periodically on Mangkang Regions, Sub District of Tugu in Semarang City. Design works of Beringin River had finished in year of 2003. In the design, there were recommendations for normalization, dike structure and jetty structure works. Hydraulic study for each condition is conducted by using hydraulic modelling of Hydrologic Engineering Centre -River Analysis System (HEC-RAS) of 3.1 version. Stream is assumed as a single reach using the upstream boundary at HM 72+88 to HM 0 (estuary). Flow hydrograph is used for upstream boundary condition and stage hydrograph is used for downstream boundary condition. In existing condition, overtopping is occurred at 22 River Sta tions at left bank and 27 River Stations on right bank, whereas the maximum flow at River Stations 37 is 3,63 m/s. By the channel normalization, overtopping is occurred at 22 River Stations on left bank and 27 River Stations on right bank, whereas the maximum flow at River Stations 57 is 4,74 m/s. By constructing the dike, overtopping is occurred at 12 River Stations on left bank and 13 River Stations on right bank, whereas the maximum flow at River Stations 37 is 3,91 m/s. By constructing the jetty, overtopping is occurred at 22 River Stations on left bank and 30 River Stations on right bank, whereas the maximum flow at River Stations 40 is 3,69 m/s. After combining the works, by constructing dike and normalization the overtopping is only occurred at 7 River Stations. Priority to perform the work series will be more effective hydraulically if it is started by dike construction, continued by normalization and jetty construction.

Kata Kunci : Penelitian terdahulu, simulasi hidraulik, prioritas urutan pekerjaan, Previous study, hydraulic simulation, work series priority