S. Sulawesi's Lake Tempe may disappear in 20 years

S. Sulawesi's Lake Tempe may disappear in 20 years

Hasanuddin Hamid, Contributor, Makassar, South Sulawesi

Unchecked deforestation has brought closer to home the threat
of Lake Tempe, some 200km northeast of Makassar in Wajo regency,
disappearing in the not-too-distant future.

The lake's reduced capacity was blamed for the major flooding
last May that claimed eight lives and inundated 15,795 houses and
7,669 hectares of rice fields. The worst-hit areas were those
along the lake.

The flood was the biggest in almost five years, worse than in
October 1998 when about 10,000 hectares of rice fields ready for
harvest, were inundated. No lives were lost then.

During the 1998 flooding, the water level of the lake was at
7.5 meters, but last May, that level rose to 9.5 m. The latest
flooding hit the neighboring regencies of Soppeng and Sidrap,
causing considerable material damage and losses.

Ludvie Achmad, head of the South Sulawesi soil conservation
and land rehabilitation center (BRLKT), said the popular lake was
deteriorating due to sedimentation.

"If things continue to go unchecked, the lake's disappearance
is simply a matter of time," he said.

During the wet season, the lake is about 30,000 hectares in
area, but during the dry season it shrinks to half that size.
Fifty thousand people live around it, with most making a living
from agriculture and fishing activities, Wajo regent Naharuddin
Tinulu, said.

Meanwhile, Ludvie said that a study conducted by the agency he
heads had concluded that the Bila and Walanae rivers, which empty
into the lake, carry some 50,000 tons of silt into the lake every
year.

Soil and garbage make up the sediment that causes the bed of
the lake to rise 5 centimeters to 7 cm annually.

Nine smaller rivers in five regencies located in the river
basins of the Bila, Walanae and Beloka rivers also contribute in
bringing mud into the lake. The lake's water, meanwhile, can
drain only through one river, the Cenranae, which empties into
Bone Bay.

"When there is a heavy rain, the water level in the lake
increases to six or seven meters, causing the lake to overflow.
During the dry season, the water level of the lake drops to only
one meter," he said.

Ludvie also said that unless serious measures were taken soon,
the sediment would increase by 10,000 tons a year. Over the past
two decades, the lake's area has shrunk 900 hectares a year.
This, he said, meant that the whole lake would be covered by
sediment in 12 years time.

He added, however, that the lake could be saved if soil
conservation measures were immediately taken. Unfortunately, the
handling of river basins in this area is quite complicated and
needs the cooperation of several agencies.

The siltation of the lake has not only made the lake shallow
in depth and shrink in size, but it has also resulted in a
reduction in the diversity of the lake's biota and a decrease in
the fishermen's haul.

Over the past five years, the lake has generated 5,000 tons to
7,000 tons of freshwater fish a year. Two decades ago, the lake
could yield 50,000 tons of fish a year and was the major source
of fish for Java, said Tinulu.

He also said that to save the lake, the Wajo regency
administration and other local administration agencies had
conducted a special study on possible dredging and water control.
The result of the study was submitted to the National Development
Planning Board (Bappenas) for fund allocation.

Meanwhile, the head of the South Sulawesi water control
service, Jantahin, said his office had drawn up a detailed plan
for the construction of a flood control dam, but that they were
waiting for a donor country that could finance the proposed
project, which was estimated to need some Rp 250 billion (about
US$27.7 million).

This dam, he said, would keep the water of the lake from
overflowing and prevent the water level from drastically dropping
in the dry season.

During the dry season, the dam would regulate the lake's water
level, while during the wet season it would keep the lake's water
at a desired level and channel any of the excess into the
Cenranae River.

The local office for soil conservation and land rehabilitation
has found it difficult to include forest rehabilitation in the
lake's catchment as the community has cleared the areas around
the forest.

Degradation of the lake has been largely attributed to
deforestation in the upstream areas. Among those responsible is
state-owned plantation company PT Perkebunan Nusantara XIV. The
forests have also been badly affected by mining activities.

Sampe Paembonan, a professor at the School of Forestry at
Hasanuddin University (Unhas), who is involved in forest
conservation in South Sulawesi, said a study conducted by the
university concluded that the mining and plantation activities
had left most of the upstream area denuded.

Research undertaken by the Center for Environmental Studies of
Unhas in cooperation with the Institute of Agriculture of Bogor
(IPB) sometime ago showed that siltation of the lake had reached
5 cm to 7 cm a year. However, Paembonan estimated that the
siltation level could be as high as 20 cm a year.

He said that immediate action must be taken by allowing the
water to flow into other places. He agreed with a proposal for
expanding the Cenranae's river basin.

Paembonan attributed the siltation process to two factors: the
movement of the Earth's crust and siltation.

He said although Lake Limboto in the province of Gorontalo was
also deteriorating and only 2 meters deep at present, Lake Tempe
would undergo more rapid damage unless efforts were immediately
taken to overcome the siltation problem.

He said to improve maintenance in the future, the local
government needs to state the purpose of the lake: is it intended
to boost fishery and recreation or agriculture? A clear purpose
would determine how the lake would have to be redeveloped, he
said.

To prevent Lake Tempe from drying up, Paembonan advised that
the most important action to take was to establish an
organization to oversee management of the lake.