Flood Embankment / Levee Crest Level & Freeboard – Quick Tool

Computes required crest level and freeboard components for a river embankment or levee at a given section, including hydraulic freeboard, wave allowance, settlement and safety margins. All levels in the same vertical datum (e.g. m a.s.l.).

1 Calculations – Flood Levels & Site

Define the local ground level, design flood level and (optionally) check flood level. All levels in metres, referred to the same datum (e.g. MSL).
Reference level at the embankment toe or floodplain where HFL is measured.
Water level corresponding to the design flood (e.g. 1-in-100 year event).
Higher check flood level (e.g. 1-in-500 or PMF). Used to comment on overtopping risk.
Current or planned crest RL. If given, the tool compares it with the required crest RL.
Used only in the interpretation text (no change in equations).

2 Calculations – Freeboard Components & Criteria

Base hydraulic freeboard is linked to water depth; wave, settlement and other allowances are added explicitly. Adjust the default factors to match your practice / code.
Used as Fhyd = max(kd · depth, Fmin). Typical values 0.2–0.5.
Lower bound on hydraulic freeboard, even for shallow depths.
Significant wave height at embankment; can be from reservoir / fetch calculations.
Wave allowance Fwave = kw · Hw. Set 0 if you ignore waves.
Extra height to account for consolidation / settlement of the embankment.
Allowance for future raising, climate change, unknowns. Set 0 if not used.
Margin for survey / construction tolerances (e.g. ±0.1 m).