I asked an environmental specialist about the beach erosion in northern Penang Island, and this is what he had to say:
A groyne in the UK; Butterworth used to have similar groynes at the beach fronting the RMAF base - Photo courtesy of Wikipedia
Various modelling studies were done during the construction of the Penang Bridge, land reclamation of Batu Maung and Bayan Baru and the North Butterworth Container Terminal to try and predict the likely impact on sediment transport and the likely erosion and sedimentation.
However, when one side is the open sea, such as along the north coast of Penang Island, the volume of water flowing through is not affected by the fixed volume of the straits.
When any structure is constructed, such as land reclamation or the construction of a “groyne” to prevent beach erosion, it will interfere with the natural beach processes.
