Ah, you are looking for "areal flooding" or "flash flooding" maps. That is not going to be covered in those overlays. Maybe a Google search for "areal flooding map Philippines" would help you out? Not sure if they have those but that is what you are probably looking for.
Okay thanks found what I was looking for anyone else interested go to this link, and zoom in, and choose what you wish to look at: (5/25/100 Year) Met-Hydro Decision Support Infosys This is sort of what I was after mate, zooming right in either means we do not get flooding outside of Dumaguete and Siaton areas or there is no data for these outer areas. Many years ago my wife's family lived in Siaton and were caught in a major flood stranded in the middle of the river for almost a week before being rescued. That is the kind of thing I was hoping to avoid. Looking at the attached screenshot I took of the map it looks like only the two areas are majorly affected due to the river systems here...
3 areas in your screenshot. Bayawan, Siaton and Dumaguete. Zoom out a bit more and I suspect you will see Bais, Tanjay and San Carlos also have flooding as well. It's only natural that the larger cities/towns will have flooding....civilization tends to grow where fresh water hits salt water.
Thanks Brian, that's another great link. Definitely looks like the south part of the city is lower risk - though I get what other posters are saying about asking locals as well and using my eyes. I don't mind so much if I can't get into the city if the Banica floods - I can just hole up at home and wait it out.