### Runoff

Hi! I have a question about runoff. Since this model can't model pollutant reduction benefits from LID, I want to calculate it using EMC by myself. I'll use equation L=EMC*Q, where EMC is mg/m3, Q is m3/day. But the runoff modeled from SWMM is m3/s and I set reporting time is 1 hour. How can I convert these hourly data which unit are m3/s to monthly data which unit are m3/day?

#### Replies

• Yes, that will work but did you know that you can sum the monthly rainfall and monthly runoff using the SWMM 5 Statistics Tool?

• Thank you so much! I didn't know it before. It's really time saving!

• Hello Sunny,

i think you just need to multiply the flow by 86400 or the number of seconds in day to get m3/day

• Hi Bob! Thank you! I have another question. I used two and half years data and all of the runoff, losses data I got from  SWMM are hourly data. To make it easier for visualizing, I want to make a graph by myself which x axis is month. Now I have hourly data, to get the monthly data, can I just add all of the data for one month? (runoff and losses data) For example,

 Losses Runoff Date Time (mm/hr) (CMS) 01/01/2011 1:00:00 0 0 01/01/2011 2:00:00 0.05 0.01 01/01/2011 3:00:00 0.02 0 01/01/2011 4:00:00 0.02 0 01/01/2011 5:00:00 0.02 0 01/01/2011 6:00:00 0.02 0.03 01/01/2011 7:00:00 0.02 0 01/01/2011 8:00:00 0.02 0 01/01/2011 9:00:00 0.01 0 01/01/2011 10:00:00 0.01 0 01/01/2011 11:00:00 0.01 0.04 01/01/2011 12:00:00 0.01 0.02 01/01/2011 13:00:00 0.01 0.01 01/01/2011 14:00:00 0 0

......

For the runoff and losses of January, I added all of hourly data to get monthly data. Is it correct?