KARAKTERISTIK PENDANGKALAN WADUK BILI-BILI PASCA LONGSORNYA GUNUNG
BAWAKARAENG
Siltation Characteristics of Bili-Bili Dam after Mt. Bawakaraeng Collapse
*
Syamsul Arifin Lias, **Nasaruddin, ***Muhammad Said
*
Jurusan Ilmu Tanah, Fakultas Pertanian, Universitas Hasanuddin, **Head of DCO (Dam Control Office) Waduk
Bili-Bili, BBWS Pompengan-Jeneberang, *** Assistant Engineer, Yachiyo Eng. Co. Ltd.
(Coresponding email: syam_lias@yahoo.com)
ABSTRACT
The purpose of this study was to determine the total capacity of reservoir and effective storage of
Bili-Bili Dam after siltation occur post-Mt. Bawakaraeng collapse, knowing the large amount of
sediment that settles in the reservoir after reservoir base changes, and determine the rate of
sediment coming into the Bili-Bili dam in each year. It is an important component in considering
efforts to maintain the function of Bili-Bili Dam.The study was conducted by the method of data
collection is to find the data and information about the Bili-Bili dam ranging from preliminary
data plan until now. Data was analyzed with the same approach with the initial planning of BiliBili Dam construction in 1997. Data used to determine the type of reservoir that classified by
Borland and Miller (1953) in USBR (1973), subsequently plotted on a logarithmic graph to form
the slope (slope) an equation that shows the value of “m” to determine the type of reservoir.
Measurement data of reservoir base 2001 to 2009 are used to determine the new elevation to
obtain the volume of sediment that settles in the reservoir. Estimated distribution of sediment in
the reservoir is determined by the Empirical Area Reduction method. The results showed that the
volume of sediment deposited on the Bili-Bili Dam in 2001 until 2009 amounted to 75,033
million m3, while the rate of sediment into the reservoir after a landslide is 13,061 million m 3 per
year. Total volume of Bili-Bili Dam reservoir during 10 years of operation reduced to 342,678
million m3 of 375,066 million m3 with an effective storage capacity in 2009 amounted to
227,948 million m3.
Pattern of sediment silting not converge on a particular area, but spread to the upper reservoir
and form a sediment layers. The layers of sediment could be able to move and close the intake
with age reservoirs. After 5 years of the occurrence of landslides, the new zero elevation of BiliBili Dam is 62.00 m asl., Equal to the lowest elevation measurements in 2009, while after 10
years of the occurrence of landslides new zero elevation is 63.00 m asl., with the assumption that
the rate of sediment entrance to the reservoir is 13,061 million m3 per year.
Keywords: Siltation, sediment, Bili-Bili Dam, and Mt. Bawakaraeng collapse.