Tuflow and estry manual Version 3



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Property

Flag

Required

Description

Elevation

n/a

Mandatory

The water level elevation in m above the datum at which the hydraulic properties apply.

Width

n/a

Mandatory

The storage width in m.

Area

A

Optional

The effective flow area in m2. If omitted, the area is calculated based on the elevations and widths starting at an area of zero at the lowest elevation.

Wetted Perimeter

P

Optional

The wetted perimeter in m. If omitted, the area is calculated based on the elevations and widths assuming a symmetrical channel.

Manning’s n

N

Optional

The variation in Manning’s n with height. Default value is the Manning’s n is that assigned to the channel using the Manning_n attribute.

Manning’s n Factor

F

Optional

A multiplication factor that varies with height applied to the Manning’s n value. This option may be used instead of the N flag above.



3.13.2Node Storage (NA) Tables


Storage at a node is defined using either a storage table of elevation versus surface area or using the widths of the channels. All nodes must have their storage defined by one of these approaches. Note that checks are also made for the following.

  • The lowest elevation of a node must be below the lowest channel connected to the node.

  • The highest elevation of a node is used to detect instabilities. Therefore, the highest elevation should be above the highest expected water level, unless Depth Limit Factor is used to extend storage properties above the highest elevation.

  • The storage (surface area) of a node must not be zero at any level.

Minimum NA is useful for stabilising 1D nodes that have small surface areas, particularly at shallow depths or when wetting and drying.

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