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Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator

Easily calculate and compute culvert hydraulics inlet / outlet control headwater depth (fhwa) calculator with accurate equations, live formulas, and expert guidance.

Internal pipe diameter.

10-year or 50-year peak runoff flow.

Square edge with headwall ≈ 0.038; Beveled edge ≈ 0.029; Grooved socket ≈ 0.032.

FHWA HEC-5 standard unsubmerged exponent ~0.67.

Calculated Result
1.24 m

Headwater (HW)

Headwater (HW)

1.24 m

Headwater Depth Hw Meters

1.24

Headwater To Diameter Ratio Hw Over D

1.04

Barrel Flow Velocity M Per Sec

3.09

Overtopping Risk

Unsubmerged Weir Flow (HW/D <= 1.2)

1.24 — m

Calculation Breakdown

  1. Applied FormulaCalculates the upstream headwater depth (HW in meters) and HW/D ratio for highway drainage culverts under inlet control according to Federal Highway Administration (FHWA) HEC-5 criteria.\frac{\text{HW}}{D} = 1.0 + c \left(\frac{Q}{A \sqrt{g D}}\right)^Y

Culvert Hydraulics (FHWA) Metric Output

Interactive visualization based on your current inputs

Calculated Value
0.00.30.60.91.2Headwater (HW)

What Is the Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator?

This tool computes culvert hydraulics inlet / outlet control headwater depth (fhwa) calculator with high precision arithmetic.

How Does the Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator Work?

Calculates the upstream headwater depth (HW in meters) and HW/D ratio for highway drainage culverts under inlet control according to Federal Highway Administration (FHWA) HEC-5 criteria.

Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

HWD=1.0+c(QAgD)Y\frac{\text{HW}}{D} = 1.0 + c \left(\frac{Q}{A \sqrt{g D}}\right)^Y

Calculates the upstream headwater depth (HW in meters) and HW/D ratio for highway drainage culverts under inlet control according to Federal Highway Administration (FHWA) HEC-5 criteria.

How to Use the Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator

  1. Enter your parameters into the designated input fields to calculate the result immediately.

Step-by-Step Example Calculation

Culvert Hydraulics Inlet / Outlet Control Headwater Depth (FHWA) Calculator Example

Input Values:

culvertDiameterMeters:1.2
designDischargeFlowM3PerSec:3.5
inletEdgeTypeConstantC:0.038
inletExponentY:0.67
Worked Steps: Sample evaluation based on standard reference conditions.

Understanding Your Result

The calculated primary figure indicates the optimal or required m.

Factors That Affect the Result

  • Measurement tolerances, operational variance, and real-world conditions.

When Should You Use This Calculator?

  • Everyday budgeting, technical homework, professional estimation, and household projects.

Assumptions & Limitations

  • Assumes standard atmospheric or environmental parameters unless specified.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Double-precision IEEE 754 arithmetic with validated empirical constants.

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