Excessive sand mining threatens 'Sabo' damns

Excessive sand mining threatens 'Sabo' damns

Sri Wahyuni, The Jakarta Post, Yogyakarta

Sand excavation activities on the rivers at the base of Mount
Merapi in Central Java are now threatening Sabo (lava control)
dams constructed along the rivers to control the flow of hot lava
from the volcano, a researcher warns.

"If nothing is done about it, I'm afraid it will damage the
Sabo constructions, and once the volcano erupts, lava could
destroy hundreds of hectares of rice fields and housing areas
around Mount Merapi," said Sabo researcher Hariyadi Djamal of
Yogyakarta Water Resources Research Institute of the Ministry of
Settlement and Regional Infrastructure.

Speaking on the sidelines of a one-day international
symposium on sediment-related issues in the Southeast
Asia region in Yogyakara Wednesday, Djamal said that his research
institute had noted that some 14,000 cubic meters of sand was
being quarried from the base of Mt. Merapi every day.

"The amount of sand quarried should be reduced to a "safe"
level. Otherwise, it will not just destroy Sabo dams but also
cause degradation of the Progo River, where most of
the tributaries end up," said Djamal, adding that his institute
had yet to conduct a study on the acceptable amount of the
quarried sand.

Sand quarry activities near a Sabo dam construction in
Jurang Jero (Magelang, Central Java) and Kaliboyong
(Sleman, Yogyakarta), for example, once damaged censor wires used
to monitor and measure the rainfall and flood levels.

"It has yet to cause damage to the construction but
it will if nothing is done about it," Djamal said.

According to Djamal, the negative impacts of sand dredging in
the rivers near Mt. Merapi could in fact be reduced by providing
tight control on it.

He particularly urged local governments to ban sand dredging
near Sabo dams.

"The safe areas for taking sand from the base of Mt. Merapi is
several hundred meters on either side of the dams, and should not
exceed five meters below the base of the dams," he said.

An integrated coordination among related government and non-
government institutions including the sand quarrying companies,
according to Djamal, was needed to control and help reduce the
negative impacts of dredging.

A Japan-sponsored Yogyakarta Sabo Technical Center has from
1972 to 1998 built 13 Sabo dams, of between six to 11 meters long
in the Merapi area as well as in the regions of Magelang and
Klaten (Central Java) and Sleman (Yogyakarta).

During the eruptions in 1992, 1994, and 1998, Kaliboyong Dam 6
was instrumental in diverting the lava from flowing to and
damaging Kaliurang resort and other northern regions of
Yogyakarta. The Kali Lamat and Kali Putih dams were also hailed
for protecting the southeastern regions of Magelang.