Numerical investigation of coastal sediment transport for assessment of coastal erosion of a Philippine coastline using a 3D hydrodynamic model

The Philippines, being an archipelagic country with at least 36,000 km of coastline, has been identified to have more than 20 areas that are at risk of coastal erosion. One of these areas, located in Ibajay, Aklan, was studied wherein a 3-dimensional numerical model using Delft3D was created in order to simulate and analyze the prevailing hydrodynamics and sediment transport. The model was calibrated using continuous water level and velocity data obtained from sensors deployed during two separate field surveys. Model results showed excellent agreement with observed data and sufficiently captures the existing tidally dominated hydrodynamics of the study area. The temporal variability of the hydrodynamics and transport of sediments was investigated by simulating flows during flood-ebb, spring-neap, southwest-northeast monsoon, and 2-year long conditions. Areas of erosion and deposition were identified based on the results of the long-term simulation. None of these areas were located along the coastline except on the area near the stream where local erosion and deposition happens. Based on this, it can be concluded that the study coast is stable under prevailing tidal conditions. The obtained results can be used as baseline data for managing future coastal developments of the municipality and the methodology conducted in this research can be applied on other erosion-prone coastlines nationwide.