WMS:1D-HYD Centerline Coverage Type

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The 1D-Hydraulic Centerline coverage has three possible attribute types: general, centerline, and bank. If the arc is a general arc type then it does not participate in the building of a hydraulic centerline and only provides additional visual detail to the model. A bank arc is used to mark left and right bank points for any cross sections that are automatically extracted from a digital terrain model.

A centerline arc defines the stream thalweg, and provides the backbone of the hydraulic model definition. It generally follows the flow of the river, and may not actually be centered between the two defined left and right bank arcs of the floodplain or channel. Its direction should be from upstream to downstream as this is the way HEC-RAS commonly views the river. This automatically defines which is the left bank and which is the right bank (think of standing up river and looking downstream when determining left and right). A centerline has as attributes the river reach properties as defined in the River Reach Attributes dialog shown below.

The river reach properties include: a River Name, a Reach ID (internally assigned and not editable), a Reach Name, a Computational Length for the river (generally equal to the length but this could be different in order to account for additional sinuosity), a Feature Length, a Start Station, and End Station.

1D-CenterlineExample.png RiverReachAtt.jpg

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