Nagan Raya Port (Indonesia), Sediment Study to Guide Maintenance Dredging

This is a research case at an industrial port that serves a power plant, not a port authority management program

The port of the 2 x 110 MW Nagan Raya coal-fired power plant was built by Indonesia's State Electricity Company in Aceh Province (Zikra et al., 2021). Since operations began in 2013, the port has had large amounts of sedimentation inside the port and at the ship entrance. The breakwater was extended and some groins were built, but these did not fully protect the port basin (Zikra et al., 2021). Silt is removed from the navigation channel by regular dredging. A 2021 peer-reviewed study by researchers at Institut Teknologi Sepuluh Nopember evaluated the effect of maintenance dredging, with the goal of reducing the sedimentation problem (Zikra et al., 2021)..

Approach

Collect field data. The team measured bathymetry, wave height, current speed, water level variation and sedimentation around the port. It also used wind data for 2004 to 2018 and measured tides during the bathymetric survey (Zikra et al., 2021).

Model sediment movement. The team used the Delft3D modeling system to simulate the sedimentation pattern around the port. It used the ShorelineS model to predict coastline change (Zikra et al., 2021).

Build a sediment budget. Dominant winds and waves come from the south to west, so wave-driven currents in the surf zone run from south to north. The study estimated that about 40,000 to 60,000 cubic meters of sediment reach the port each year (Zikra et al., 2021).

Review the disposal site. Dredged material from the navigation channel was dumped at sea at a site 11 m deep and 1.5 km from the shore. The study recommended moving disposal further out, to at least 20 m depth or 20 miles from the coast (Zikra et al., 2021).

Consider alternatives to repeated dredging. The study proposed a sand bypassing system. Such systems usually run continuously and can prevent sedimentation over time (Zikra et al., 2021).

Results

The sediment model showed up to 1 m of sedimentation in parts of the inlet channel. In the modeled scenario, material placed at the existing dumping area did not return to the mouth of the basin (Zikra et al., 2021). The study's outputs are recommendations. The source does not report whether the port adopted them.