Calculator Inputs
Formula Used
This calculator uses linear wave theory to estimate the dynamic pressure variation with depth, plus an optional hydrostatic component referenced to still water level (SWL).
Notes: z is positive upward from SWL, and negative underwater. The wave number k is solved by Newton iteration.
How to Use This Calculator
- Choose Metric or Imperial to match your drawings.
- Enter wave height H and wave period T.
- Enter water depth h at the structure toe.
- Set the elevation z where pressure is needed.
- Select dynamic and hydrostatic components as required.
- Optionally compute resultant force over an elevation range.
- Press Calculate to display results above the form.
- Use the download buttons to export CSV or PDF.
Example Data Table
These examples illustrate typical coastal design inputs. Results will vary by site conditions, structure geometry, and the chosen elevation z.
| H | T | h | z | Assumed ρ | Approx. total pressure at z |
|---|---|---|---|---|---|
| 2.5 m | 8 s | 6 m | −1.0 m | 1025 kg/m³ | ≈ 21–30 kPa (case dependent) |
| 3.5 m | 10 s | 9 m | −2.0 m | 1025 kg/m³ | ≈ 35–55 kPa (case dependent) |
| 1.8 m | 6 s | 4 m | −0.5 m | 1000 kg/m³ | ≈ 12–20 kPa (case dependent) |
For impact/slamming loads on breaking waves, use a dedicated impact model or code guidance.
Design context for wave pressures
Wave action on seawalls, revetments, and quay walls is typically checked at multiple elevations to capture how pressure changes from crest to toe. This calculator evaluates pressure at a chosen z relative to still water level, helping screen facing thickness, joint detailing, anchor loads, and construction tolerances for coastal structures.
Input data quality and site conditions
Select a wave height consistent with the governing return period and apply nearshore transformations where needed. Pair it with a representative period for the spectrum, because period controls wavelength and the depth decay term. Water depth should reflect the toe level at the design water level (including tide and surge). Even a 0.5 m depth change can noticeably shift the pressure profile in shallow water.
Dynamic versus hydrostatic components
Dynamic pressure from linear theory represents oscillatory water motion about still water level, while hydrostatic pressure represents the mean water column below SWL. Toggling components supports staged works: temporary cofferdams, partially drained basins, or early concrete pours. For final design, include both when the wall is exposed to waves and standing water, and document the selected combination.
Resultant force for wall checks
Global checks often require a resultant force per unit width over a vertical range rather than a single-point pressure. The force option integrates pressure between ztop and zbot, supporting bending checks, sliding friction verification, and tie-back demand estimates. Combine the resultant with a lever arm to estimate overturning moment, then compare against resisting weight, anchors, and passive resistance.
Limitations and good practice
The method assumes regular, non-breaking waves and small steepness, so it is best for preliminary sizing and comparisons. Breaking wave impact, slamming, air entrapment, and highly irregular bathymetry can produce higher localized loads and require code guidance or modeling. Validate units, use realistic density (about 1025 kg/m³ for seawater), apply conservative safety factors, and keep export files with the design package. Re-check elevations against drawings to avoid sign errors during later project reviews.
FAQs
1) What does the elevation z represent?
z is measured from still water level. Use negative values underwater and positive values above the waterline. This lets you evaluate pressure at a specific level on the wall, such as toe, mid-height, or near the crest.
2) Why does wave period change the result?
Period controls wavelength through the dispersion relation. Longer periods generally have longer wavelengths and slower decay with depth, which can increase pressures at deeper elevations compared with short, steep waves for the same height.
3) When should I exclude hydrostatic pressure?
Exclude hydrostatic pressure when there is no standing water against the wall, such as during a dewatered construction stage or when comparing only the oscillatory wave component. For final operating conditions, it is usually included.
4) What safety factor should I apply?
Choose a factor that matches your design standard, load combination rules, and uncertainty in wave inputs. Many preliminary checks use values around 1.2–1.5, but project requirements and codes should govern the final selection.
5) What is the resultant force output?
Resultant force is the integrated pressure over a vertical range, reported per unit width of structure. It supports checks for bending demand, sliding resistance, and anchor forces when combined with an appropriate lever arm for moment calculations.
6) Can this be used for breaking wave impact?
No. Breaking and slamming loads can be impulsive and much larger than linear theory estimates. Use code-based impact methods, physical modeling, or validated numerical tools when breaking is expected at the structure face.