Hydropower Headworks – Design Workflow & Toolbox

A compact workflow showing how the Water Hammer, Hydraulic Jump & Stilling Basin, and Anti‑Scour tools fit together in a typical hydropower headworks / barrage design process.

Water Hammer / Surge – Tool Hydraulic Jump & Stilling Basin – Tool Anti‑Scour / Scour Depth – Tool

1 High‑Level Design Workflow

This is a typical sequence for preliminary headworks design. In real projects you will iterate back and forth, but this gives a clean, explainable structure for reports and reviews.

1
Define hydraulic design cases Inputs

Choose characteristic discharges and operating scenarios:

  • Maximum design flood / check flood.
  • Normal operating discharge (e.g. 100% / 50% turbine load).
  • Extreme transients: gate slam, load rejection, pump trip, etc.
2
Check transient pressures – Water hammer Structural / equipment

Use the water hammer quick‑check to see if transient pressures are compatible with penstock / tunnel design and gate / valve ratings.

Open tool: Water Hammer / Surge – Quick Check
  • Input: ΔV, closure time tc, wave speed a, pipe length L, static head.
  • Output: surge head ΔH, Hmax/Hmin, pressure envelope for wall design.
3
Design stilling basin – Hydraulic jump & tailwater Energy dissipation

Size the stilling basin so that the hydraulic jump remains within the basin and the energy is dissipated safely before the flow attacks the riverbed.

Open tool: Hydraulic Jump & Stilling Basin – Quick Design
  • Input: Q, B, y1 at basin entrance (or V1), g.
  • Output: y2, ΔE, jump type, jump length Lj, basin length Lb.
4
Evaluate scour & foundation embedment Anti‑scour

Combine regime scour, local scour and protection stability to fix: foundation depth, floor level, and toe protection.

Open tool: Anti‑Scour / Scour Depth – Multi‑Formula
  • Lacey (Q / q) → general scour depth & anti‑scour foundation depth.
  • Shields → is the bed material itself “live” or relatively stable?
  • Izbash → rock size & thickness for apron / toe protection.
  • HEC‑18 / CSU → local scour at piers / training walls.
5
Refine with seepage / uplift & structural design Next tools

With scour depths and basin geometry fixed, the next steps usually are:

  • Seepage and uplift checks under the floor (Bligh / Khosla / numerical).
  • Floor thickness, keys and cutoffs, drains and relief wells.
  • Structural design of piers, gates, abutments and training walls.

Future tools can plug in here: seepage path / uplift quick check, floor stability & thickness, etc.

2 Toolbox Summary – “Which Tool for Which Question?”

Use this matrix when you’re in the design office and just want to remember “which tool do I open for this?”

Water Hammer / Surge Pressures

Main question:
“What are the extreme transient heads and pressures in my penstock / tunnel for a given closure / opening event?”

  • Quick Joukowsky vs. closure‑time classification.
  • Hmax / Hmin for structural and equipment checks.
  • Good for screening before full transient modelling.

➜ Tool: water_hammer_quick_check.php

Hydraulic Jump & Stilling Basin Energy

Main question:
“What does the hydraulic jump look like and how long does my stilling basin need to be?”

  • Computes y2 from y1 and Fr1.
  • Estimates ΔE and jump length Lj via several correlations.
  • Suggests basin length Lb and indicative USBR type.

➜ Tool: hydraulic_jump_stilling_basin.php
➜ Theory: Hydraulic Jump & Stilling Basin – Theory

Anti‑Scour / Scour Depth Scour

Main question:
“How deep can the river scour, and what embedment / rock protection do I need?”

  • Lacey (Q / q) → regime scour & foundation depth.
  • Shields → is D50 at, below, or above critical?
  • Izbash → rock size for given velocity & density.
  • HEC‑18 / CSU → additional pier scour depth ys.

➜ Tool: anti_scour_multi_formula.php
➜ Theory: Anti‑Scour – Theory & Notes

(Future) Seepage & Uplift Stability

Main question:
“Given my floor level and cutoff depths, are uplift and piping under control?”

  • Bligh creep lengths / Khosla pressure distribution.
  • Approximate uplift at key points under the floor.
  • Check against allowable uplift for a given floor thickness.

➜ Placeholder for a future tool – will naturally slot after scour & basin sizing.

3 References & Further Reading

The formulas in the tools follow standard open‑channel hydraulics and scour practice. For detailed design, always fall back on primary references and local codes:

Your tools are designed to sit “above” these references: fast checks with transparent equations, then you dive into the manuals when you need full detail or code compliance.