Pre 2014 Blogs

Calibrating total width of catchment using SWMM5

Posted by Chow Ming Fai on August 13, 2010 at 11:17pm
Hello,
I am not familiar on using SWMM for quantity and quality modeling. i need some helps here.
I have a problem on calibrating the total width of catchment in SWMM quantity modeling. Figure shown below is my studied catchment. the surface runoff is flow from right to left. How can i calculate the total width of catchment? and how to calibrate SWMM quantity modeling on its total width?
Hopefully i can get some help from you all. Thank you.

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Comments

  • Robert Dickinson August 15, 2010 at 11:10am
    You should still adjust the width individually for each subcatchment but compare the peak flows for the combined flows to your monitored data. Unless you want to model S1, S2 and S3 together then you are best off estimating the width for each subcatchment.
  • Chow Ming Fai August 15, 2010 at 10:45am
    Thank you for your help. However, the flow measurement was only taken at the outlet of the whole catchment (Out 1). if i want to calibrate the runoff quantity, how can i obtain the width of the whole catchment? Am i combine the total width of subcatchment S1, S2 and S3? Thank you for your comment.
  • Robert Dickinson August 14, 2010 at 11:41am
    Originally, when SWMM was developed the width parameter was the collection length of the subcatchment. For example, it would be the gutter length on a street going to an inlet. In your case one easy way to estimate the Width for the subcatchment going to inlet S3 would be

    Width = Area of Subcatchment in Hectares / Length of Overland Path to Inlet S3 in Meters
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