Renun River dilemma brought about by deforestation
By Benget Simbolon Tnb.
JAKARTA (JP): The government's plan to divert the Renun River into Lake Toba in North Sumatra to raise the lake's water level has been received with skepticism.
The Renun River diversion may not be sufficient to save Lake Toba, which has dropped by about three meters from 905.14 meters above sea level over the last 15 years.
It may also fail to generate enough electricity for the Renun Hydroelectric Project, which is being developed by a Korean company in Sumbul sub-district, a mountainous area on the western part of the largest lake in the Southeast Asia region.
The local government has planned to divert the river, which runs about 450 meters above the lake, through a tunnel, which is also under construction as part of the hydroelectric project.
Expectations were high when the government started the development of the project in 1999, with three principal goals. Firstly, to increase the water level of Lake Toba, which continues to be decline. Secondly, to generate up to 2 x45 MW of electricity. Thirdly, to increase the water outflow from Lake Toba into the Asahan River, which in turn will improve the power- generating capacity of the Sigura-gura Hydroelectric Project. The current reduced capacity of Sigura-gura has forced PT. Inalum, an aluminum-producing company downstream on the Asahan River, to purchase electricity from the state-owned electricity company PT PLN.
But the declining volume of water in the Renun River has dampened such high expectations. The problem is so serious that the Lake Toba Heritage Foundation has expressed its concern over the worsening situation.
Jansen H. Sinamo, the secretary general of the foundation, confirmed that the water volume of the Renun River has dropped significantly during the last few years. Its water flow has decreased from 22.1 cubic meters per second to about 10.
According to a report authored by the National Institute of Aeronautics and Space (LAPAN), the drop in the Renun River's water volume has resulted from significant climatic changes brought about by large scale deforestation in its water catchment area.
Despite the fact that there are many illegal loggers operating in the region, LAPAN put the blame mainly on the controversial PT Indorayon, a pulp and paper company, which was forced to temporarily halt its operations in Porsea two years ago.
LAPAN estimates that Indorayon has felled approximately 100,000 hectares of forest in North Tapanuli, Central Tapanuli, South Tapanuli, Dairi and Simalungun. But in view of the fact that it exploited both natural and production forests, which are of unequal density, the estimate for the destroyed forested area very likely exceeds 100,000 hectares.
Sinamo said in Dairi alone, where the Renun River originates, the deforestation has seriously affected about 36,000 hectares of land.
"We're facing a real crisis," he said when asked about the ratio of damaged forests to the total forested area in the Renun's water catchment area, about 80 kms southwest of the Renun Hydroelectric Project.
He said only an intensive reforestation program would rehabilitate the environmentally-damaged area. This is particularly important as it will also improve the water volume of 11 other smaller rivers in Dairi, which also contribute to the total water inflow to Lake Toba.
Actually, a very serious reforestation program should be pursued in all the water catchment areas around Lake Toba. That would improve the water volume of 145 rivers, which empty into the lake.
Sinamo warned that any reforestation program should take into account the area's ecosystem. A good reforestation program will maintain the ecosystem, not harm it, he noted.
It is widely known, for example, that a reforestation program in the 1980s, which only involved planting pine trees around Lake Toba, caused the extinction of indigenous freshwater fish species in Lake Toba, such as what is called "ihan Batak" -- a kind of fish that is only found in the lake.
He said that "We still have enough time to save the project. If we're serious about doing it now, the reforestation program will start paying off in three years."
The Renun project needs proper supervision by those concerned with environmental issues. Otherwise, the project will become another laughing stock in the country.