Overview:

Channels are the fundamental objects of the DSM2 grid. The Channels table allows you to enter channel connectivity, parameters and geometry. Channels connectivity is defined by an upstream and downstream node numbers of the channels. Two child tables describe the locations and geometry of user-described cross-sections in the selected channel. Note that a default initial condition is required for every channel number in the DSM2 grid, and this is entered seperately in the Channel Initial Conditions table.

Tables:


CHANNEL

The CHANNEL table defines the connectivity, length, friction and dispersion characteristics of a channel.

Field Descriptions

CHAN_NO
Channel number. This is the identifier of the channel, and corresponds to the number you typically see on a grid map.
LENGTH (ft)
Length of the channel reach
MANNING
Manning's n friction coefficient for the whole reach.
DISPERSION
Dimensional dispersion factor.
UPNODE
Number of the upstream node at which channel is connected.
DOWNNODE
Number of the downstream node at which channel is connected.

Table Info

Identifier:
CHAN_NO
Parent Table:
Table is parent
Include Block:
GRID

XSECT

This table lists files where bathymetric cross-sections are specified by the user using the CSDP format. The table lists the fraction of the distance along the reach (from upstream to downstream) at which the user cross-section is located. These cross-sections will be interpolated by the model at computational points. Overspecification of geometry is a frequent source of user error/misconception, please see usage notes below. Also note that this style of input and the XSECT_LAYER "single file" format below should not be freely mixed for a given channel -- use one or the other.

Field Descriptions

CHAN_NO
Channel number where cross-section is located
DIST
Fraction of distance from upstream node to downstream node where cross-section is located
FILE
CSDP-formatted file where cross-section geometry is defined.

Table Info

Identifier:
CHAN_NO, DIST
Parent Table:
CHANNEL
Parent Identifier:
CHAN_NO
Include Block:
GRID

XSECT_LAYER

The Cross-Section Layer Table lists geometric information about each cross-section. This information is in the form of lookup tables of hydraulically important quantities such as area, width and wetted perimeter.

Field Descriptions

CHAN_NO
Channel number in which cross-section is located.
DIST
Fraction of distance from upstream node to downstream node where cross-section is located
ELEV
Elevation from bottom at which properties are known. The area, width, etc. apply to this elevation, and channel properties between elevations are linearly interpolated.
AREA
Area of channel from bottom to cross section(sq ft). Ignored if Area disagrees with the integral of WIDTH.
WIDTH
Width of channel at top (ft).
WET_PERIM
Wetted perimeter of channel at given elevation.

Table Info

Identifier:
CHAN_NO, DIST, ELEV
Parent Table:
CHANNEL
Parent Identifier:
CHAN_NO
Include Block:
GRID

Examples:

CHANNEL with XSECT_LAYER cross-section
CHANNEL with XSECT (csdp) cross-section


Usage Notes: