GVF Profile
Water surface profile in one prismatic channel by the standard step method, from a control depth, with the profile type.
Results
Enter your values; the answer appears here as you type.
The curve appears with a result.
- Standard step
- The energy equation is solved from section to section with the average of the two friction slopes, Sf = (n Q / (1.486 A R2/3))2.
- Direction
- Subcritical flow is controlled from downstream, so the page computes upstream; supercritical flow is computed downstream from an upstream control. A depth on the wrong side of critical is refused.
- Profile type
- M, S, C, H or A with 1, 2 or 3 by the slope and where the control depth lies against normal and critical depth (Chow, 1959).
- Stopping
- A profile that reaches critical depth stops there and says so. The flow changes regime at that point, and the page does not locate a jump.
The calculator is tested against the cases below every time its code changes.
| Case | What | Reference | Values compared | Largest difference | Result |
|---|---|---|---|---|---|
| The table loads with the calculator. The same results are in verification.json. | |||||
Compared with an independent fine integration of dy/dx = (S0 − Sf)/(1 − Fr2) written apart from this code, 0.01 ft at the end of the reach. No published worked example or reference program has been compared for this page: a HEC-RAS comparison was tried and could not be completed.
- One prismatic channel: one section, one n, one slope. No transitions, bridges or culverts, no change of section, and only friction losses. For a natural stream use HEC-RAS.
- Steady flow, one regime at a time. Mixed-flow profiles and the location of a jump are not computed; compute each side and use the Hydraulic Jump calculator to compare them.
- The accuracy depends on the step. Try a shorter step: the depth at the end should not change.
- What depth do I use at the control?
- The depth a control sets: a known tailwater, or critical depth just above a free fall or a change to a steep slope. Normal depth is reached only far from any control.
- Why does the page refuse my depth?
- Going upstream the flow must be subcritical; going downstream supercritical. Change the direction, or check the depth against the critical depth the page shows.
- Can I attach the calculation sheet to a report?
- You can print it and include it as a supporting calculation that you have checked. It is a calculation aid, not a sealed engineering document: the engineer of record reviews and is responsible for what goes into a report.
| Topic | Reference |
|---|---|
| Method | Chow, V.T. (1959). Open-Channel Hydraulics, Chapters 9 and 10. USACE, HEC-RAS Hydraulic Reference Manual, one-dimensional steady flow. |
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A free calculation aid using the published methods above. Not a sealed engineering document; the engineer of record is responsible for design. HERO E&C · TBPELS Firm F-27793.
Full disclaimer
A free calculation aid. This calculator applies the published methods named on this page to the inputs you enter. It is not a sealed engineering document, has not been reviewed by a licensed professional for your project, and no warranty is expressed or implied. Check the results independently before using them for design, bidding or permitting.
The criteria of the reviewing agency decide which methods and values apply to a design. The engineer of record is responsible for the design.
Using this calculator does not create an engineer–client relationship. Calculations run in your browser; your inputs are not sent to or stored by HERO E&C. HERO E&C · TBPELS Firm F-27793.