| Flow type | Flow regime | Control at section | Intermediate between flow types | Culvert entrance condition | Culvert flow condition | Culvert exit soffit underwater? | Nature of flow in culvert |
|---|---|---|---|---|---|---|---|
| 0 | -- | Approach | -- | Part full | Part full | No | Free |
| 1 | Low head | Culvert entrance | -- | Part full | Part full | No | Free |
| 2 | Low head | Culvert exit | -- | Part full | Part full | No | Free |
| 3 | Low head | -- | -- | Part full | Part full | No | Submerged |
| 31 | -- | -- | 1, 2, or 3 and 4 | Part full | Full | Yes | Submerged |
| 4 | Submerged culvert | -- | -- | Full | Full | Yes | Submerged |
| 41 | -- | -- | 3 and 4; 61 and 4 | Full | Part full | No | Submerged |
| 42 | -- | -- | 6 and 4; 62 and 4 | Full | Full | No | Submerged |
| 5 | High head | Culvert entrance | -- | Full | Part full | No | Free |
| 51 | -- | Culvert entrance | 1 and 5 | Full | Part full | No | -- |
| 52 | -- | Culvert entrance | 2 and 5 | Full | Part full | No | -- |
| 6 | High head | Culvert exit | -- | Full | Full | No | Free |
| 61 | Adverse slope | Culvert exit | -- | Full | Part full | No | Free |
| 62 | -- | Culvert exit | 1 or 2 and 6 | Full | Full | No | -- |
| 7 | -- | Departure | -- | -- | -- | -- | -- |