owillis28
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Hope this works
Unit Hydrograph Information
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owillis28 --
I think your PDF has A LOT of good information. However, those PDFs while containing good information are also busy, so I thought I would point out what I personally feel is information key to understanding Unit Hydrographs:
1. Unit Hydrograph theory, by definition, is the hydrograph of one-inch of DIRECT RUNOFF from a storm of a specified period.
2. The physical characteristics of the basin (slope, shape, size, roughness, etc.) of the drainage basin are assumed to be constant so principles of proportionality apply.
3. (As a consequence of #2) For a given rainfall duration (i.e. time of NET rainfall), the time of DIRECT SURFACE RUNOFF is constant. Stated another way, Direct Surface Runoff = net rainfaill.
4. (As a consequence of #2) The ordinates of the runoff hydrograph are proportional to the runoff volume.
5. The Unit Hydrograph is developed from the specific duration of the rainfall event according to the degree of time subdivision (e.g. 0.2 in/hr for a 5-hr storm, 1 in/hr for a 1-hr storm, 3 in/hr for a 20-minute storm).
The aforementioned ideas are important because in my experience, manipulation of the information is key ... but you must grasp the controlling concept(s) in order to apply the solution technique to a slightly re-stated problem.
I will look for some Unit Hydrograph problems to post for you or anyone else to gauge thier understanding.
JR
I think your PDF has A LOT of good information. However, those PDFs while containing good information are also busy, so I thought I would point out what I personally feel is information key to understanding Unit Hydrographs:
1. Unit Hydrograph theory, by definition, is the hydrograph of one-inch of DIRECT RUNOFF from a storm of a specified period.
2. The physical characteristics of the basin (slope, shape, size, roughness, etc.) of the drainage basin are assumed to be constant so principles of proportionality apply.
3. (As a consequence of #2) For a given rainfall duration (i.e. time of NET rainfall), the time of DIRECT SURFACE RUNOFF is constant. Stated another way, Direct Surface Runoff = net rainfaill.
4. (As a consequence of #2) The ordinates of the runoff hydrograph are proportional to the runoff volume.
5. The Unit Hydrograph is developed from the specific duration of the rainfall event according to the degree of time subdivision (e.g. 0.2 in/hr for a 5-hr storm, 1 in/hr for a 1-hr storm, 3 in/hr for a 20-minute storm).
The aforementioned ideas are important because in my experience, manipulation of the information is key ... but you must grasp the controlling concept(s) in order to apply the solution technique to a slightly re-stated problem.
I will look for some Unit Hydrograph problems to post for you or anyone else to gauge thier understanding.
JR
