Bay Cities Face Silting Impacts

KOMPAS/SAIFUL RIJAL YUNUS

Ships of various types are anchored in Kendari Bay as seen on Friday (26/3/2021), in Kendari, Southeast Sulawesi. Sedimentation and reclamation over the last few decades have made the bay area of 900 hectares even more critical.

KENDARI, KOMPAS - A number of provincial capitals in bay areas in eastern Indonesia are facing changed sea landscapes due to excess sedimentation, piling garbage and land reclamation. This has not only forced a relocation of infrastructure, interfered with shipping activities, but also caused dwindling fishing catches and environmental damages.

The worrying condition, as monitored by a Kompas team, is found at Kendari Bay (Southeast Sulawesi), Palu Bay (Central Sulawesi), Manado Bay (North Sulawesi), Ambon Bay (Maluku), Youtefa Bay and Yos Sudarso Bay (Humboldt) in Jayapura (Papua).

Kendari Bay is experiencing a critical phase.

In Kendari Bay, piling silt is carried by the Wanggu River flow. The water has a higher turbidity, in contrast to the outer seawaters. Massive development sees restaurants line up on the shore at the expense of breakwater mangroves.

“Kendari Bay is experiencing a critical phase. Based on the environmental change variables, in the last four decades, sedimentation has reached 66 million cubic meters. The silting rate is up to 1.1 million cbm a year,” La Ode Alwi, a lecturer in environmental science at Halu Oleo University, Kendari, said in early March.

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Severe sedimentation at the watersheds of 13 rivers and tributaries has affected the depth level of the bay, from 23 m in the middle of the 1970s to around 6 to 7 m currently.

According to research conducted by the Sampara Watershed Management Agency, the bay’s underwater silt slope has spanned to 101.8 hectares with the sea depth of 9 to 10 m in the last 13 years.

The bay’s shipping-worthy area shrank from 1,186.2 ha to 1,084.4 ha in 2000.

The bay’s sedimentation has impacted the sea biota life and because of its obstruction to shipping and freight loading and unloading activities, forced the cargo port to be moved to the mouth of the bay.

"The relocation was related to the [decreasing] depth of the bay, but mainly because of the construction of the bridge. Cargo ships found it difficult to enter,” said Debby Duakaju, PT Pelindo IV Makassar senior manager, who is also the former general manager of PT Pelindo IV Kendari.

KOMPAS/FRANSISKUS PATI HERIN

Cultivation of fish in floating nets owned by residents in Ambon Bay, Ambon City, Maluku, on Monday (29/3/2021). Pollution at the bay will have a devastating effect on these businesses.

In Ambon Bay, several points near the foot of the Merah Putih Bridge identified to be suffering the most sedimentation, have markers installed to alert vessels against passing.

Satellite image data from the Indonesian Institute of Sciences (LIPI)’s Deep Sea Research Center recorded the bay’s sedimentation area at 102.56 ha in 1994. It increased to 168.13 ha in 2007, which showed an annual silting rate of 5.43 ha in 13 years.

As a result, settlements near the bridge, such as Hative Kecil in Sirimau district, have become prone to being flooded by tidal waves.

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“In the past, it would usually happen during the monsoon [December-February]. Now, it is anytime the tidal waves come,” said Aksa Noya, a resident of Hative Kecil.

At the settlement, which has about 40 houses and a population of 200, sea water may surge inland, up to about 50 m.

LIPI Deep Sea Research Center associate engineer Daniel Pelasula expects more areas on the coast of Ambon Bay to be inundated by tidal floods. Apart from sedimentation, tidal floods are exacerbated by rising seawater levels.

In Jayapura, sediment silt in Humboldt (or Yos Sudarso) Bay and Youtefa Bay is also made up of garbage.

KOMPAS/VIDELIS JEMALI

Basri Badong (47), a fisherman from Lere Village, West Palu District, Palu City, just returned from fishing in Palu Bay, Sunday (28/3/2021). He admitted that there were fewer fish because Palu Bay was experiencing sedimentation.

Fish Catches

Sedimentation in the two bays began to worsen in 2001, which Yehuda Hamokwaron, head of the Papua Watershed and Coastal Institute, blames on the development in the buffer zone of the Cycloop Nature Reserve and the riverbank with the bay being its estuary. The formed slope of silt has buried the seagrass and coral reef ecosystems.

Meanwhile, local fishermen around Palu Bay and Manado Bay have been complaining about dwindling catches due to excess sedimentation.

In the 1990s, I could still get two containers of fish around the mouth of the bay. Now, even up to 5 kilometers from the estuary, I can get only one container.

Basri Badong, 47, a fisherman at Lere village, West Palu district, said that since 2000, the bay area has become increasingly cloudy because of the thickening seabed.

"In the 1990s, I could still get two containers of fish around the mouth of the bay. Now, even up to 5 kilometers from the estuary, I can get only one container," Basri said.

The sedimentation-caused marine environment has also damaged the coral reefs in Manado Bay. According to Ferdy Tuilan, 47, a fisherman at Tandipang Sindulang 2, fishermen have to sail 8 to 9 nautical miles (14-16 km).

"Over time, the catches are getting smaller and less frequent," he said. (JAL / FLO / FRN / OKA / VDL)

This article was translated by Musthofid