It could be that one of the belts split and is flapping against various parts of that area of the engine. It may also be a loose pulley or pulley bolt too. The bolts on the water pump pulley are hard to reach and torque down, so check those for sure.

Take off the upper timing belt cover and see if you can locate the problem. If you don't see anything, it should at least be able to figure out where it is coming from.

Good luck Andrew.