HGP Engineering

|Overtopping Discharge DashboardAll ToolsOpen Pipe Flow Tool

Internal engineering tool based on the methodology in Floods and Reservoir Safety, 4th Edition, using Chapter 5 wave prediction and overtopping checks with Chapter 6 suggested allowable overtopping limits.

1.03 l/s/m
Calculated Overtopping
0.20 m
Required Freeboard

Site and Wind

m
102000
deg
0360
mAOD
0500
m/s
545
deg
090

Chapter 5 requires the engineer to assess fetch and wind approach carefully. In this simplified tool, the raw wind direction is retained for project traceability while obliquity is applied directly through the overtopping reduction factor.

Adjustments

fT
0.51.5
fW
11.4
fD
0.81.2
fN
0.71.2

Structure and Surface

1:x
18
deg
090
gb
0.41
gf
0.41

Performance Targets

m
02
l/s/m
0.00150
Current Overtopping
1.027
l/s/m
Required Freeboard
0.200
m

Embankment Schematic

Still water levelRc = 0.20 mU/S slope 1:3.0Wall angle 18.4 degHs = 0.23 m

Wave State

Altitude Adjustment (fA)1.115
Design Wind Speed (U)23.400 m/s
Significant Wave Height (Hs)0.230 m
Peak Wave Period (Tp)1.391 s
Mean Wave Period (Tm-1,0)1.264 s
Deep Water Wave Length (Lm-1,0)2.494 m
Breaker Parameter (xi)1.097

Reduction Factors

Wave Obliquity Factor (gamma_beta)1.000
Wall Influence Factor (gamma_v)1.000
Zero-Freeboard Discharge44.069 l/s/m
Exponential Decay Length0.253 m

Assessment

Calculated Overtopping1.027 l/s/m
Required Freeboard for Target0.200 m
Protection Check

Current discharge sits within the Chapter 6 suggested limit for "Well protected crest". Appropriate for a well protected crest and good grass cover on the downstream face.

Target discharge entered: 1.030 l/s/m

Suggested Limits (Chapter 6)

No overtopping≤ 0.001 l/s/m
Bare clay or erodible fill≤ 0.1 l/s/m
Good grass cover≤ 1 l/s/m
Well protected crest≤ 10 l/s/m
Strongly protected crest and rear slope≤ 50 l/s/m

Overtopping vs Freeboard

Required Freeboard vs Target q

Obliquity Sensitivity

Method Snapshot

Method Summary

This dashboard follows the simplified wave and overtopping methodology set out in Chapter 5 of Floods and Reservoir Safety, 4th Edition, with tolerable discharge checks aligned to the suggested limits in Chapter 6.

1. Derive wind speed adjustments, significant wave height, mean period, and breaker parameter from Chapter 5.

2. Calculate mean overtopping discharge from freeboard, then reverse the relationship to test a target allowable discharge.

Use the sliders to explore sensitivity quickly, then compare the result against Chapter 6 suggested limits for crest and downstream protection.