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Govt urged to boost man-made dams supervision
The Indonesian Institute of Sciences (LIPI) has called on the government to set more stringent management and observation standards on all dams and reservoirs in the country, particularly those constructed with compact earth
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The Indonesian Institute of Sciences (LIPI) has called on the government to set more stringent management and observation standards on all dams and reservoirs in the country, particularly those constructed with compact earth.
That is necessary in order to prevent a tragedy like the Situ Gintung dam burst from occurring anywhere else.
Head of the Geotechnology Research Center at LIPI Edi Prasetyo Utomo said LIPI researchers had analyzed a number of reservoirs which were prone to damage or susceptible to severe erosion in upstream areas.
Edi said the major problems with managing compact-soil dams included controlling river flows and inspecting the dam structure.
Inaccurate rainfall data currently hampers the early detection of problems with the dam structure, while a lack of supervision along river basins can lead to area conversion and sedimentation.
“Information on rainfall in the upper reaches should be updated all the time, by using for example an automatic rainfall gauge [ARFG]. Permeability should be measured with a geo-electrical device,” said Edi at a discussion on the Situ Gintung tragedy at the LIPI campus in Bandung on Tuesday.
The death toll from the dam burst in Tangerang is currently sitting at 99, with around a hundred people still unaccounted for.
Based on satellite data, Edi said the distance between the upstream area and the Situ Gintung dam was around 28 km, which meant an ARFG unit should have been installed every 10 km at the very least. Such a device, said Edi, could help prevent future incidences at an inexpensive cost of around Rp 10 million each.
Besides that, he said, bank embankments should be inspected regularly to ensure they were impermeable and did not have cavities, which could trigger erosion and increase the potential of bursting.
Head of the Limnology (Inland Waters) Research Center at LIPI, Gadis Sri Haryani, said dams should be free of infrastructure at least 100 meters from the dam so inspection processes could properly take place.
She said reservoirs and dams were crucial to managing water during the rainy season and were also a key source of water supply during the dry season. There are more than 500 reservoirs and dams in Java, 230 of which are located in Jakarta, Bogor, Depok, Tangerang, Bekasi and West Java.
“Around five percent of these dams have vanished due to conversion, despite the significant role they play managing water,” said Gadis.
She said managing upstream areas was essential because damage sustained to conservation areas could intensify water volumes and deposit huge quantities of sediment and runoff. A key dam of concern, said Edi, was the Bilibili dam in South Sulawesi. It has upstream areas located in Mount Bawakaraeng, which is prone to landslides.
Edi said a landslide which struck the area in 2004 stretched 11 km and was the largest ever recorded. However, no technology has since been applied to prevent the Bilibili dam from clogging with silt, posing a major risk of collapsing.
“Many villages in Gowa and Makassar are vulnerable to any potential landslide if the dam gives way as a result of increasing physical degradation. Supervision at upstream areas should be boosted to prevent the likelihood of this occurring,” said Edi.
