I would like to know if it is possible to convert the duration of a unit hydrograph.
For example, I have a unit hydrograph of a storm event that lasted for about 50 hours with a peak discharge after 3 hours. How can I convert this 50-hour hydrograph into a 4-hour duration with its peak discharge being reached at around the 30-minute to 1-hour mark? Has anyone been in a similar situation?
Thank you in advance!
Yes, Minjiao is right. S-curves is the method. See for example this video: https://www.youtube.com/watch?v=wSvFrX48JOo . The method is explained there very nice.
According to the proportionality principle the Direct runoff hydrograph (DRH) ordinates are proportional to effective rainfall intensity (ERI) . Similarly as per superimposition principle DRH ordinates due to a complex storm (i.e. varying ERI) can be obtained by superimposing the DRH due to each ER. These principles can be used for changing the duration of a unit hydrograph.
But method of superimposition is applicable when a D-h unit hydrograph is available and it is desired to develop a unit hydrograph of nD hour, where n is integer. In your case n is not an integer, therefore you have to opt the S-curve method as advised by David. You can use Microsoft excel to estimate the ordinates of S-Curve addition and S-curve ordinates.
The beauty of S-curve ordinates is: you can find out any duration of Unit hydrograph by lagging these ordinates with the desired duration.....
Good luck...
- Badges
- Science topic
- Similar topics
- Geoscience
- Hydrology