PART B - EROSION CONTROL IN OPEN AND CLOSED
CHANNEL DRAINAGE
OPEN CHANNEL EROSION CONTROL
The subject of open channel erosion control was discussed in Lesson 4, Part E. Review this section if you need
to.
To review briefly, the means for protecting open channels from the damage caused by erosion are-
Checkdams.
Paving the ditch with asphalt or concrete.
Ditch linings to increase the "n" factor, such as riprap and rubble.
One commonly used method is the stilling basin. This method is most often used with culverts. Its function is to
prevent overloading the drainage system. Stilling basins or ponding will be discussed in detail in the next section.
CULVERT EROSION CONTROL
Erosion at the culvert outlet is caused by one of two conditions-turbulence or water velocity. Turbulence at the
outlet will produce bottom and side-bank scour, as shown in figure 6-2. Water velocity at the outlet flow exceeds
the erosion velocity of the soil.
Figure 6-2. Culvert outlet turbulence
6-3
EN5465
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