River Reaches

A River Reach in InfoWorks ICM is modelled as a link. The link is digitised between two nodes to define the centre line of the reach. Once the river centre line has been defined, reach geometry can be built from section data.

It is intended that river reach cross section and bank parameters, including geometry, be built from river line data. If changes to cross section/bank parameters are required, these should be made to the line data and the reach updated from the line data.

By default, river section data (accessible from the River sections field on the River Reach property sheet) and river bank data (available through the Left river bank or Right river bank field respectively) are uneditable (greyed out grid) once the river reach has been built. However it can be made editable to allow section or bank parameters to be entered manually by checking the Allow editing of river reach data option of the General page of the Options dialog.


Use this option with care as the edited data may be overwritten if the river reach is subsequently re-built or updated.

The boundary of the River Reach represents a void when generating a 2D mesh.

See the River Reach Building Tools topic for details on building and editing reach geometry and data in InfoWorks ICM.

See the Modelling Breaches in Banks and Linear Structures topic for details on modelling breaches in banks.

Base flow

River reaches are modelled with an inverse Preissmann slot in the bed of each river section. The slot is modelled as 0.1 m wide and 1 m deep, with roughness of n=0.01, and is treated as a separate panel for conveyance calculations. In each computational cell, the simulation engine adds a base flow sufficient to fill the slot in normal flow conditions with no other flow in that cell. The slope of the computational cell comes for the lowest elevation of the sections upstream and downstream and the spacing between sections.

Bank flows

Each river bank may be connected to a single object of type River Reach, Storage Area or 2D Zone into which flow from the river reach can spill.

Flow over the bank is calculated as a flow over a jagged or irregular weir.

See the River Reach - Bank Flows topic for details on calculation of flow over banks.