Culvert

We'll be using box culvert for this modelling:

  • Reach length: 100m
  • Channel slope: 0.003
  • Downstream XS: (5, 80), (5, 75), (45, 75), (50, 80)
  • Mannin's n: 0.013
  • Culvert's u/s is at 50 m (10 m d/s from 60 m)
  • Culvert is 10 m in width (or length in the perspective of river length)

![[Pasted image 20260723132117.png]]

General

  • Culvert opening called barrel

Procedure

  • Keep SI unit

Geometric

  • Enter u/s and d/s cross sections
  • Interpolate by 20
  • Open "Bridge/Culvert"
    • Options > Add Bridge/Culvert
      • Enter cross section: 50
    • Deck/Roadway
      • Distance: 10
      • Low chord: Same or less than ground elevation ![[Pasted image 20260723132952.png]]
    • Culvert
      • Shape: Box
      • Span: 9 (each box width)
      • Rise: 4 (height of box)
      • Chart: #59 - Rectangular concrete
      • Scale: #1 - Side tapered
      • Distance to u/s xs: 10
      • Culvert length: 10 (may be different than deck width if culvert extends outwards/inwards from the deck)
      • Depth block: block flow upto depth (use 0)
      • U/s & d/s invert elv: floor elevation (bottom elv within the section)
      • Total 3 barrels in 40 m (station 5 to 45); 13 dist; 5 18 31 45; mid point 11.5, 24.5, ... ![[Pasted image 20260723140556.png]]

Steady Flow

  • 3 flow profiles: 250, 500, 750
  • Reach boundary conditions:
    • U/s: Normal depth - 0.003
    • D/s: Critical depth

Analysis

  • Use mixed condition

Observation

  • At PF 2 and 3, overflows
⇪