PERENCANAAN NORMALISASI SUNGAI BERINGIN DI KOTA SEMARANG
ABSTRACT: Reduced green open
areas and forests in upstream of Beringin watershed areas is affect the
run-off, so it is possible resulting in increased surface run-off, decreased
time of concentration, and at the same time a decrease in groundwater recharge.
Thus the flow in the rainy season will tend to rise and discharge will decrease
in the dry season. Comparison of river's Qmax (usually in the rainy season) and
Qmin (in the dry season) is very large. The greater the ratio of river's Qmax
to Qmin, indicating the further degradation of the watershed. Upstream areas in
the South is quite hilly with steep slopes, with a height of 12.5 m to 250 m.
The issue of Beringin River originated from land use change in the uplands,
especially on open land (forest, shrubs, and farm or agricultural) into housing
and settlement, causing flooding in the watershed Beringin. To calculate the average maximum
rainfall-average using Thiessen polygon method with three rainfall stations
that affect which is the Mijen, Tugu, and Mangkang Waduk. Rainfall data were
used from 2003 till 2012, while the flood discharge plans taken from the
calculation method of HSS Gama I with a
return period of 10 years at 180.59 m3/s. Normalization is planned in the main
river along the 7.18 km, from the estuary (STA 0) to the arround Mangkang
regency (STA 23). Varying the width of the river is 14 m of STA 0 to STA 8, 12
m of STA 9 to STA 19, and 10 m of STA 20 to STA 23 with the same slope at 1:
1.5. This cross section plan has previously been simulated with HEC-RAS 3.1.3
program and the results was they were able to accommodate discharge plan that
occurs. Safety height of 0.6 m was added in each cross section above the water
level of the river. Revetments also added to the bend of the river in STA 22-23
with a length of 200 m and a height of 4m. This project implementation is
scheduled for 28 weeks with a budget plan of of Rp 16,881,359,000.00.
Penulis: Dimaz Pradana Putra,
Suharyanto, Hari Nugroho
Kode Jurnal: jptsipildd140537
