Upstream Water Level Calculator

Model headloss through pipes to predict upstream level. Compare scenarios with units, notes, and checks. Download tidy outputs for bidding and inspection teams fast.

Inputs

This tool estimates upstream water level for a pipe or culvert based on energy losses. Use it for quick checks during drainage layout and constructability reviews.

Gravity is set automatically from units.
Total discharge through the culvert.
Use clear inside diameter, not nominal.
Flow path length between inlet and outlet.
Typical range: 0.015–0.03 for turbulent flow.
Include entrance, bends, screens, transitions, etc.
Invert at the inlet (same datum as downstream).
Invert at the outlet.
Depth of water at the outlet end.
Notes are included in CSV/PDF exports.

Example data table

Sample inputs and computed outputs for quick verification.

Q D L f K zdown TW depth zup Upstream WSE
0.50 m³/s 0.80 m 30 m 0.02 1.50 100.00 m 0.60 m 101.20 m 100.705 m
12.0 ft³/s 2.50 ft 80 ft 0.022 2.00 340.00 ft 1.20 ft 341.10 ft 341.480 ft

Values in the table are illustrative; field conditions may vary.

Formula used

The calculator uses the energy equation with Darcy–Weisbach friction and lumped minor losses.

A = πD² / 4
V = Q / A
hv = V² / (2g)
hf = f (L/D) hv
hm = K hv
htotal = hf + hm
WSEdown = zdown + TW
WSEup = WSEdown + htotal
Depthup = WSEup − zup

How to use this calculator

  1. Choose SI or US units and keep inputs consistent.
  2. Enter flow rate, diameter, and culvert length.
  3. Provide a friction factor and a combined minor-loss coefficient.
  4. Enter upstream and downstream invert elevations (same datum).
  5. Add tailwater depth at the outlet to define downstream WSE.
  6. Press Calculate to view upstream WSE and depth above invert.
  7. Use CSV/PDF exports to attach results to site reports.

Use this calculator to confirm safe upstream water levels.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.