STUDI PERENCANAAN TANGGUL UNTUK PENANGGULANGAN BANJIR SUNGAI KONAWEHA BAGIAN HILIR KABUPATEN KONAWE

The overflow of Konaweha River, which almost occurs every year, has caused damage
to the natural embankments on the riverbank. Because the function of the embankment is
very important for flood retention, it is necessary to plan a new embankment design.
Embankment planning is centered on the downstream Konaweha River. Before the design
of the embankment, it is necessary to estimate the plan flood discharge with a certain
period. To determine the period of the planned flood discharge, a return period of 5 - 25
years is usually used. In this study, a return period of 20 years is used. The planned flood
discharge with a predetermined period is used to determine the flood water level which
will be used to prepare the height of the embankment and also to calculate its stability.
HEC-RAS software was used to determine the flood water level, and geostudio software
was used to design and calculate the stability.
Embankment planning with discharge calculations using a 20-year return period
obtained a planned flood discharge of 2455.882 m3 / s with a flood level in the most critical
condition as high as 1.36 m on the left river (P11) and 1m on the right river (P5). In
planning the height of the embankment, it is necessary to consider the amount of the guard
height. For the embankment height with a discharge of 2000 - 5000 m3 /ms, a guard height
of 1.2m is given. With the planned embankment design, the stability of the embankment
against landslides and seepage was controlled. With the help of geostudio software, the SF
value on the P11 embankment is 3.15 on the inside and 2.98 on the outside, which means
it meets the requirements, where the SF number> 1.5. While at P5 the SF value is obtained
at 3.19 and 2.31. And for the seepage value, a value of 3.08 x 10-5 was obtained on the
P11 embankment and 1.68 x 10-5 on P5, where the seepage allowance Q was 24.558
m3/ms. From the results of the stability calculation, it can be concluded that the design of
the embankment plan is qualified.