Curve Number

[Lalith]

Hi,

I am trying to calculate curve number for a watershed using soil type and land use data. I am required to use watershed boundary, longest flowpath and drainage point shapefiles from another program. I also have GIS shapefile of soil type and land use.

First I made the drainage coverage and projected watershed boundaries, longest flowpath and drainage point shapefiles. created the polygons and calculated basin data. Then I tried to calculate the CN using soil and landuse shapefiles. I used a land use table created by me using the soil and land use data. Please see the attached document for more details. However, my CN calculation provide me an empty output with the following message on it. Would you please help me figure this out.

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                           Runoff Curve Number Report
                               (Generated by WMS)
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Fri Oct 20 13:43:33 2017

Thank you,

Lalith

[Chris Smemoe]

Lalith,

Your curve number report should show each of your basins with a list of the land use/soil type combinations and how the curve number was computed.  In your drainage coverage, have you assigned a "Drainage boundary" type to the polygons?  Do you have streams in your drainage coverage so an outlet is assigned to the downstream point on your stream?  Have you converted to soil/land use data to coverages in the map module of WMS or are you using the shapefiles directly?  If you have converted the soil/land use shapefiles to coverages, do polygons exist in this coverage and are the correct ID's (land use ID's and soil group letters-A, B, C, or D) assigned to the coverages?  If you are using the shapefiles, are you using the correct fields to represent soil groups and land use ID's?  Do the shapefiles or map land use and soil data overlay your watershed sub-basins?  Are you using the most recent version of WMS 10.1?  If you are doing these things, you should be getting results.  If you are not, there may be something else wrong and I'd recommend contacting tech support.

Hope this helps,

Chris