Eroding riverbanks threaten flash floods

Wahyoe Boediwardhana ,  THE JAKARTA POST ,  BATU   |  Fri, 06/26/2009 1:21 PM  |  East Java

Upstream water catchment areas and the banks of East Java's Brantas River have been massively eroded and may be susceptible to flash floods, officials and experts have warned.

The latest survey released in 2003 said that upstream water catchment areas, situated in the Bromo Tengger Semeru National Park, Malang regency, and the Mt. Arjuna and Mt. Welirang areas including Batu and Mojokerto cities, had experienced 2.2 tons of erosion per hectare annually, a 300 percent increase from the condition of the river in the 1980s.

The head of the monitoring division at East Java's Provincial Administration Environmental Agency, Drajat Gunawar, said that of the 111 springs surveyed in upstream Batu by the public firm, Perum Jasa Tirta I, 57 had experienced gradually decreased flows of natural springs in the area.

The annual sedimentation rate of the Sutami dam, he said, had also reached 5.4 million cubic meters between 1988 and 2003, diminishing the dam's ability to effectively contain water and reducing the capacity of the dam to hold water to 43.6 percent.

"The dam is now only able to contain 253 cubic meters, down from 142 cubic meters," Drajat told a three-day dialogue in Malang, East Java, on Thursday.

The forum was attended by representatives from 15 city and regency environmental agencies, five manufacturers in East Java, academics and a number of NGO's.

With an annual capacity of 2.5 billion cubic meters of water, the Brantas River has long been a reliable source of water, supplying water to 83,000 hectares of agricultural fields and hydroelectric plants and generating 1 billion kilowatts per hour annually.

The river also supplies water to 15,000 hectares of aquaculture ponds, 206 million cubic meters of water per annum to households and 129 million cubic meters of water to industries every year.

According to data from Perum Jasa Tirta, which was released in 2005, the profits from the Brantas River are valued at Rp 1.2 trillion (US$117.6 million) annually.

The dialogue suggested that accelerated erosion will ultimately effect 25 percent of areas in East Java.

The river runs through nearly 14 cities and regencies and 13.7 million people rely on the river for their livelihood.

"The main cause *of the serious erosion* is illegal logging and land management that have disregarded land conservation efforts," said Drajat.

He said all stakeholders should be held responsible for restoring the banks of the Brantas river.

Sharing similar sentiments, resource management scientist, Arif Lukman Hakim, said the government, the private sector and the public must work hand-in-hand to tackle the problem.

"All this time, public participation has been weak in helping restore *the riverbanks*," he said.

Among the recommendations issued during the dialogue were calls to implement comprehensive management, through environmental agencies and people-based sustainable programs.

Redesigning land use according to ecological necessities, as well as taking preventative measures to tackle environmental destructive were also proposed.

The event ended with a plan to issue a declaration to save the eroding riverbanks in upstream areas to prevent possible floods and the shortage of clean water.

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