Pls go and check out the new footbridge over Sg Air Itam, in front of Suffolk House. I believe this is the major culprit to your flood woes. Previously, there was an existing bridge built of steel trusses, which cleanly spanned over the stream. No problems. The architect for the Suffolk House restoration decided that it would not match the style of his project, so decided to replace it with an old-style bridge with round concrete culverts. Not only does this seriously restrict the volume of water moving under, it can also trap branches and leaves. In a storm situation, the river will definitely overflow. The drainage for the whole area including Lim Lean Teng Rd and the State Mosque discharges into this river.