Topographic Map

SWMM users:

I am a PhD student at the University of Guelph, Canada. As part of my research I am planning an experiment in which various groups of modellers from different universities will model runoff on an undeveloped area of approximately 20-60 ha.

I was wondering if any member of this list could provide me with such topographic map. Suggestions on where I can get such a map would also be appreciated. The real location of the area will not be cited in my thesis or in any intance during the development of the study.The map is supposed to represent a hypothetical area.

It does not matter where the area is located. However, a detailed map with countous of approximately 0.1 m appart from each other is what I am looking for. If there is choice, a hilly area is preferable.

I thank you in advance for your help. I wish you and your family happy hollydays.

Eduardo Queija de Siqueira

It does not matter where the area is.

You can get electronic topo maps (USGS) from a site, Topozone. You can
also download them and reconstruct a map as needed, but it is somewhat of a pain. Or you can pay at other sites for more workable files.

Bill T.

Eduardo:

You can download 1:24,000 USGS top maps in raster format (TIFF files) from the USGS website

http://edc.usgs.gov/webglis

These maps are called Digital Raster Graphics or DRGs and include contours at 10-20 ft interval.

Alternatively, you can use 1:24,000 (30-m resolution) scale digital elevation models or DEMs which provide ground elevation data. DEMs are in a GRID format but you can convert them to a vector format (contours) using a GIS software package, such as ArcView Spatial Analyst.

Unfortunately, neither of these (DRGs or DEMs) provide contour information at 0.1m contour interval. Data for such a small contour interval can only be obtained from low resolution digital orthophotos which are usually not available in public domain, but many cities in USA and Canada have this data. Your best bet would be to approach a city like that. Good luck.

PS: You can always convert a DEM to any contour interval including 0.1m but the output really represents interpolated values rather than 0.1m data. Interpolated elevations are not very accurate but may be adequate for your study.

Uzair M. Shamsi, Ph.D., P.E.
shamsiu@usfilter.com