Well,

You can use intensity with rain interval 1hr

Unfortunately SWMM (as of version 5) does not provide many options for flood mapping. You can have overflows simply leaving junctions, ponding atop them, or routed through edges representing roads or channels (+ floodplains). These computations require the same inputs as any normal simulation, with the addition of the extra parameters for ponding/1D routing. Flood mapping is better simulated using 2D routing software (starting from perhaps HEC-RAS or Flood Modeller).

Rainfall intensity and sometimes with slope and aspect data

Felipe Hernández Thanks for suggesting Flood Modeller. But to prepare urban flood map, is storm water drainage data compulsory.

Mukesh M S: "... to prepare urban flood map, is storm water drainage data compulsory[?]"

It depends on the flood type: if your town is by a river that would overflow (from upstream rain), you might not need to take into account the built storm water infrastructure (but also you would not want to use SWMM anyway, and would prefer to go with HEC-RAS). On the other hand, if the storm would make the storm sewer overflow, or if their capacity is not enough to evacuate the water fast enough away from a flooding area ("flash flood"), then it is very important to consider how the storm drains and other infrastructure would behave.