I am working on urban runoff modeling using a grid based distributed
model, I want to select a study site for my research, new residential
area, I can do simulation on DEM from 1m and higher. I want urban area
(small- 5-10 ha), I need very detail DEM, the topography of urban areas
is very complex, I need also to consider the shape of the roof ,
probably I will end up working on a grid size of less than 2.5 m, to
incorporate all the detail of pervious and impervious surface,
including the roof. I am not sure the best way to get a DEM (less than
2.5 m), digitize from contour map? Or from fine-scale multispectral
satellite imagery? Field survey ? Also how to incorporate the details
of the roofs and other BMPs structures? Any suggestions appreciated.

Thanks,