ReachLocationSpan Property

Specification of connection as 'start' and 'end' does not have any impact on the computations, apart that positive flow is considered from start to end. Therefore, it is recommended to specify the start-end in the direction of predominant flows, or to set the ReverseDirection flag.

The type of the reach is specified by the cross section for that reach. It may take the form of one of the 'standard' pipes (Circular, Rectangular, O Shaped, Egg-Shaped), or any closed or open cross section shape (CRS/Natural Channels).

The LocationSpan defines the geographical position of the reach.

Typical types of reaches are the sewer link and the river branch.

A sewer link is featured by:

• Connected in each end by specifying a node.
• Constant cross-section geometry, and constant friction properties along the entire length.
• It is specified as a conduit between two nodes. A link is considered as either a straight line or a drawn polyline between two nodes.
• Usually a link connects to the adjacent nodes at their bottom levels, but it may also connect above their bottom level. This is called the invert level. The start- and the end- invert level must be specified in the first and last coordinates of the LocationSpan. Specified levels below bottom level of the connecting nodes is not valid.
• A link is often characterised by material, which determines the Manning friction coefficient (Manning) or the Colebrook White coefficient (Equivalent roughness). The material is is as such not represented, though the friction formulation is specified in the cross section module.

A river branch is featured by:

• Connected to other reaches by specifying a location. Nodes usually are not specified explicitly in the setup, but created on the fly when required (at all junctions).
• Varying cross-section geometry, and varying friction properties along reach.
• At connection points, river branches usually define cross section bottom levels that equals. However, if "free outflow" properties from a tributary branch is desired, this can be achieved by specifying a higher cross section bottom level in the tributary connection end (at least 0.5 cm difference).