Wave and current characteristics for navigation safety assessment at Kalbut Port, Indonesia

Abstract

Kalbut Port, located in Situbondo, East Java, Indonesia, is an important port serving small vessels operating routes to the Madura Islands and tankers transporting liquefied petroleum gas (LPG) and crude oil. Ensuring navigational safety and efficient loading and unloading operations under variable wave and current conditions requires a comprehensive understanding of the local hydro-oceanographic characteristics. This study quantitatively investigates the current and wave conditions at Kalbut Port using secondary data and Delft3D hydrodynamic and wave modeling. The simulations were conducted for the east and west monsoon seasons. The results indicate a mixed tidal regime with a predominance of semi-diurnal characteristics. Dominant winds originate from the southeast during the east monsoon and from the west during the west monsoon. Significant wave heights reach 0.5 m during the east monsoon and 0.7–0.8 m during the west monsoon, while current velocities remain relatively low, with maximum values below 0.3 m/s during the west monsoon. Within the port basin, wave heights decrease to approximately 0.1 m due to the sheltering effect of the breakwater and the progressively shallower bathymetry. Model performance was evaluated against observed tidal elevations and significant wave heights. Tidal validation yielded an RMSE of 0.013 and an MAE of 0.009, whereas wave validation produced an RMSE of 0.131 and an MAE of 0.105. These relatively low error values indicate that the model adequately represents the hydrodynamic and wave conditions in the study area. Overall, wave and current conditions at Kalbut Port remain below the applicable navigation safety thresholds, indicating a relatively low navigation risk for both small vessels and tankers. The findings provide a scientific basis for assessing and mitigating navigation risks and supporting safer maritime operations at Kalbut Port.