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Three alternative RoR layouts

Short answer

Three RoR layouts: headrace canal with free surface flow for gentle valleys; pressure tunnel with surge tank for steep rocky terrain; dam-toe with short penstock for low-head rivers. All include intake, desander, waterway, penstock, powerhouse, chosen by topography, geology and cost.

Prepare three alternative layout plans and sectional drawings of ROR hydropower plants.

Three common RoR layouts are given with plan and section sketches.

Alternative 1: Headrace canal (free surface flow)

Plan
 River ~~~~~\       Canal ___________
 Weir|Intake=Desander==============\ Forebay
                                    \ Penstock
                                     PH-->River
Section
 weir  canal (gentle slope)  forebay
 ____    _________________   |
     \__/                 \__| penstock
                              \_PH

Suitable for gentle valley slopes; low cost; open canal can be damaged by landslides.

Alternative 2: Headrace tunnel (pressure) with surge tank

Plan
 Weir/Intake -> Desander -> Tunnel ==== Surge tank
                                          |
                                        Penstock
                                          |
                                          PH -> Tailrace
Section
 Intake======= tunnel =======(ST)
                              \ penstock
                               \_PH

Used for steep, rocky terrain and long bends; safe from landslide; high cost.

Alternative 3: Dam-toe/short penstock (low head)

Plan
 ~~~ River ~~~~ Barrage + Powerhouse in line ~~~~
Section
  U/S  |barrage|  D/S
 ~~~~~~|  PH   |~~~~
       |intake |

Powerhouse is placed at the barrage; no canal or tunnel; for low-head, high-discharge rivers in the Terai.

In each layout, the intake, desander, headworks, waterway, powerhouse and tailrace are labelled, and the layout is chosen from topography, geology and cost.

✓ Answer checked by Claude Opus 5.5 (high effort)

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