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Defining an actual storm in WMS


mysnaredcult
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I'm having a problem in defining an actual storm event.

Everything up to the point of setting HEC-1 parameters is done with ease.

Now, I got a storm event that took place over 9 days (between Jan-1-1982 and Jan-9-1982). I got a simple table in which rainfall depth in mm for each day is determined.

In HEC-1 Job control, what date should I be entering? Is it Jan-1-1982? And then, when editing HEC-1 parameters for the basin, in the precipitation card, I chose the Basin Average (PB) dialogue. There is an entry for the average precipitation in mm there. What would be the correct value? Is it the average value of the rainfall depth for the 9 days? Or is it the total?

I'm asking these questions because I'm running the model and the Hydrograph results seem unreasonable in terms of the runoff volume it produces and the time to peak as well...

Please Help me, anyone.. It's really urgent.. I would appreciate a quick response..

Thanks...

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Hi,

You should be able to enter your 9-day daily rainfall storm event. You need to make sure your time is in minutes (1440 minutes/day). It would be better if you had more frequent rainfall data. If you enter your rainfall in mm, everything else in your model must be metric units and you will need to toggle on the "Metric" option in the HEC-1 Job Control dialog. Otherwise, you can convert your rainfall to inches and use English units for your areas and everything else. Make sure the "Incremental data" option is turned on in the rainfall XY series dialog so WMS writes a "PI" card instead of a "PC" (cumulative precipitation) card for your rainfall data.

Look at the HEC-1 manual under the "PB" and "PI" cards (toward the end of the manual) for more information about what to enter for your rainfall. Also, looking at the HEC-1 output file (ending in ".out") will give you useful information on why you're not getting much outflow from your HEC-1 model. According to the HEC-1 manual, the Basin total precipitation in inches (mm) needs to be entered for the PB card. The PI card will define the precipitation distribution.

WMS doesn't actually use the date for anything significant other than writing to the HEC-1 file, but you can enter 1-1-82 for your starting date in the Job control.

I hope this helps,

Chris

I'm having a problem in defining an actual storm event.

Everything up to the point of setting HEC-1 parameters is done with ease.

Now, I got a storm event that took place over 9 days (between Jan-1-1982 and Jan-9-1982). I got a simple table in which rainfall depth in mm for each day is determined.

In HEC-1 Job control, what date should I be entering? Is it Jan-1-1982? And then, when editing HEC-1 parameters for the basin, in the precipitation card, I chose the Basin Average (PB) dialogue. There is an entry for the average precipitation in mm there. What would be the correct value? Is it the average value of the rainfall depth for the 9 days? Or is it the total?

I'm asking these questions because I'm running the model and the Hydrograph results seem unreasonable in terms of the runoff volume it produces and the time to peak as well...

Please Help me, anyone.. It's really urgent.. I would appreciate a quick response..

Thanks...

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