Flows and Transport in Rivers - Hydro-Environmental Analysis: Freshwater Environments - page 88

A river cross section is typically measured perpendicular to the low direction, as illustrated in
Figure 4.6. The cross-sectional geometry of a river is represented by a series of points, each point
speciied by a pair of X and Z values. The value X denotes the distance of the point along the cross
section from some starting point, by convention on the left bank facing downstream. The ground
elevation, with respect to a datum, is denoted by Z . A cross-section proile is typically identiied by
the name of the river, the station, and sometimes by geographic coordinates (Figure 4.7).

⊥ To flow

FIGURE 4.6 River cross sections. (From NRCS. Introduction to HecRAS. Available from http://www.nrcs.
usda.gov/wps/portal/nrcs/detailfull/national/water/?cid=stelprdb1042484, 2004.)

1830

1825

1820

1815

1810

Ground

1805

Bank station

1800

0 200 400 600 800 1000 1200

FIGURE 4.7 An example of a river cross section.