Hydrological Analysis of the Situ Gintung Dam Failure
Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika No.2, Yogyakarta 55281, Indonesia
Early on the morning ofMarch 27, 2009, the Situ Gintung dam, located near Jakarta, Indonesia, and with an catchment area of 3.1 km2, failed and flooded the area below it. This disaster has awakened most of the Indonesian people, especially those who are concerned about hydraulic structures, natural disasters and sustainable water resources management. During the disaster, about 100 people died and a number of people went missing. There are hundreds of dams like the Situ Gintung dam and other big dams have been built in Indonesia. Most of these dams pose a high potential hazard to life and property if a failure or levee breach occurs. Dam failures may occur at different locations such as spillway, embankments and foundations. The failure may occur as a result of a number of problems such as overtopping, surface erosion, and piping. Dam failures due to spillway problems may occur, for instance, as a result of inadequate spillway capacity (overtopping) or spillway loss by erosion (surface erosion). In this study, the Situ Gintung dam failure has been analyzed based on hydrology analysis. Results show that heavy monsoon rainfall was not the main cause of the situ Gintung dam failure. The daily rainfall on March 26, 2009, was 113 mm that equal to a 10 year return period. Reservoir routing shows that there was no overtopping during March 27, 2009, flood, the maximum water depth on the spillway is 0.63 m. Assuming that maintenance was done well, the spillway was still safe under a 100 year return period with the maximum water level is +98.95 m. It means that the embankment was still safe with 1.05 m freeboard. Due to high water flow velocity, however, surface erosion may occur at the end of a chute spillway that consists of silt, clay and sand. Continuous scoring/erosion happened throughout the spill over the spillway, which started at around 06:00 pm and lasted until 03.00 am, resulting in a big pond at the chute spillways and surrounding areas. This phenomenon adversely affected the instability of the spillway structure. As a result, the spillway failure occurring resulted high flow discharge that reached more than 425 m3/s.
-  Wikipedia, 2011, http://id.wikipedia.org/wiki/Situ_Gintung [accessed at August 15, 2012]
-  J. R. Wilson, “Guide to Geologic Excursions in Utah and Adjacent Areas of Nevada, Idaho and Wyoming, Utah,” Geological Survey, 1992.
-  Wikipedia, 2009, http://en.wikipedia.org/wiki/List_of_dam_failures [accessed at December 13, 2009]
-  L.M. Zhang, Y. Xu, and J. S. Jia, “Analysis of earth dam failures: A database approach,” Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, Vol.3, No.3, pp. 184-189, 2009.
-  X. Y. He, Z. Y. Wang, and J. C. Huang, “Temporal and spatial distribution of dam failure events in China,” In International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research, Elsevier, 2008.
-  G. Anderson, L. Chouinard, and S. Foltz, “Condition Rating Procedures for Earth and Rockfill Embankment Dams,” U.S. Army Corps of Engineers, 1999.
-  FEMA, “Seepage through Embankment Dams,” U.S. Department of Homeland Security, Federal Emergency Management Agency, 2005.
-  B. Harsoyo, “Jebolnya tanggul Situ Gintung (27 maret 2009) bukan karena faktor curah hujan ekstrim,” Jurnal Sains dan Teknologi Modifikasi Cuaca, Vol.11, No.1, pp. 9-17, 2010.
-  BPDAS Citarum-Ciliwung, “Laporan Kejadian Tragedi Pasca Bencana Situ Gintung,” Direktorat Jenderal Rehabilitasi Lahan dan Perhutanan Sosial Departemen Kehutanan, Bogor, 2009.
-  Badan Meteologi, Klimatologi dan Geofisika (BMKG), “Analisis curah hujan seputar jebolnya tanggul Situ Gintung,” Stasiun Klimatologi Pondok Betung, 2009 (unpublished).
-  USACE, HEC HMS 3.5, 2011, http://www.hec.usace.army.mil/software/hec-hms/
-  Br. Sri Harto, “Hidrologi, Teori, Masalah dan penyelesaian,” Nafiri Offset, Yogyakarta, 2000.
-  A. P. Wibowo, T. Maduretno, J. H. L. Billy, Zulraini, and H. Utom, “Pemeliharaan Bendungan Kecil Type Urugan (Earth Dam) di Indonesia,” Special Topics Report, MPSP, Jurusan Teknik Sipil, Program Pascasarjana Fakultas Teknik, Universitas Gadjah Mada, 2009 (in Indonesian).
-  D. C. Froehlich, “Peak Outflow from breached embankment dam,” Journal of Water Resources, Planning and Management, Vol.121, No.1, pp. 90-97, 1995.