What caused 2 bodies of water to produced artificial vortex ?

Question

There is a causeway at the Johor straits built during the British colony days to allow trains to pass from Malaya to Singapore and lately are produced vortex at one side during high tide.

Is a rock fill passageway with 2 outflow pipes [1.5 m dia] partially visible during low tide that result in these 2 voltex [600mm dia] during high tide .

What i want to know is why this happening

The 2 bodies of water are Malacca straits flowing into South China Sea . Thank you for any theory given

Answer 1

Yes, any difference in water velocity will cause vortexes.