POLA PENGENDALI BANJIR PADA SUNGAI TENGGANG KECAMATAN GENUK KOTA SEMARANG DENGAN MENGGUNAKAN METODE HEC-RAS

Tenggang River is part of the East Semarang Drainage System, whose flow
area extends from the East Flood Canal in the west to the Babon River in the east.
The frequent occurrence of flooding in the Tenggang River has several factors,
namely the limited river capacity due to sedimentation, land subsidence rates,
seawater tides and overflows from the surrounding rivers. The frequent
occurrence of flooding in the Tenggang River is very interesting to study in depth
in order to find a solution. The purpose of this control pattern is to determine the
water level during the rainy season, calculate the river capacity using Hec-ras, and
the method of handling the Tenggang river flood.
Research on flood control patterns in the Tenggang river, begins with
primary data collection which includes river characteristics and geometry data,
and secondary data consisting of rain station data, maximum daily rainfall data,
and watershed characteristics data which are analyzed into the Unit Hydrograph
method. Synthetic, HEC-RAS. In calculating the flood discharge design, rainfall
data, river measurement data, andrequired river conditions are. Based on these
data, it can be calculated rainy days plan for 2,5,10,20,25 and 50 years with the
analysis of the frequency distribution of rainfall such as Normal Distribution,
Normal Log Distribution, Log Pearson III Distribution and Gumbel Distribution,
so the Pearson III Log Distribution analysis was chosen closer and more thorough.
Based on data processing with the Nakayasu method, the peak flood discharge
(QP) value is 2.35 m3/second and Q10 is 28.94 m3/second, Q25 is 31.93
m3/second and Q50 is 34.20 m3/second. The flood discharge data for the Q50
return period is then modeled and simulated in the Hydrologic Engineering Center
River Analysis System (HEC-RAS) Version 4.0 software.
Keywords: Tenggang River, Flood Analysis, HEC-RAS