HEC-14 Energy Dissipator (Stilling Basin) Designer – SAF & USBR Basin Types

HEC-14 Energy Dissipator (Stilling Basin) Designer

SAF basin • USBR Type II / III • Basin dimensions • Energy loss • 2D profile • PDF report

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📐 1. HEC‑14 Stilling Basin Design – Why It Matters

Energy dissipators (stilling basins) are used downstream of culverts, spillways, and chutes to reduce flow velocity and prevent scour. The Hydraulic Engineering Circular No. 14 (HEC-14) provides design methods for SAF (Saint Anthony Falls), USBR Type II, and USBR Type III basins. This calculator determines basin dimensions (length, width, floor elevation, chute blocks, end sill) based on incoming Froude number and discharge per unit width.

Basin selection: Fr < 2.5 → no basin; 2.5–4.5 → SAF; 4.5–9 → USBR Type II; >9 → USBR Type III.
Basin length L (SAF): L = 3.5 · y₂
Chute block height = y₁ / 2

🚀 2. Live Stilling Basin Calculator

Discharge per unit width q (m³/s/m)

Upstream velocity V₁ (m/s) – optional, computes Fr if given

Upstream depth y₁ (m) – required for hydraulic jump

Tailwater depth (m) – optional check

Basin type recommendationAuto‑select based on FrSAF basinUSBR Type IIUSBR Type III

Batch CSV (q, v1, y1)

Get PDF Report via Email

CSV Template

📊 3. Stilling Basin Profile (Section view)

📈 4. Basin Length vs Froude & History

📘 5. How to Use the Calculator

1. Enter discharge per unit width (q) and upstream depth (y₁). Velocity (V₁) can be entered or computed from q = V₁·y₁.
2. Froude number is calculated automatically; optional tailwater depth can be compared with sequent depth.
3. Select basin type or let the tool auto‑recommend based on Fr.
4. Click "Design Basin" – the tool computes hydraulic jump parameters, basin type, length, chute block height, and energy loss.
5. 2D profile shows basin elements (chute blocks, basin floor, end sill).
6. Batch CSV: upload multiple designs; output table with basin dimensions and energy loss.
7. PDF report includes the basin sketch and all parameters.

❓ Frequently Asked Questions

❓ What is the difference between SAF and USBR basins?

SAF basin (Saint Anthony Falls) is for Froude numbers between 2.5 and 4.5; USBR Type II/III for higher Froude numbers (4.5–9 and >9 respectively). Type III includes chute blocks and dentated sill.

❓ How accurate is this tool?

It follows HEC‑14 equations and is suitable for preliminary design. Final design should be verified with physical modeling or hydraulic software.

❓ Can I use this for culvert outlets?

Yes, SAF basins are commonly used for culvert outlets. Ensure that the tailwater depth is sufficient to maintain the jump.

🌐 Standards & References

HEC‑14 (FHWA) – Energy Dissipators | USBR Stilling Basins | SAF Basin Design Manual

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© ERH HEC‑14 Stilling Basin Designer – Based on FHWA Hydraulic Engineering Circular No. 14. All data processed locally.