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The key points from this module are:
- Culvert scours are a subdivision of Jet scours.
- A water body, such as a river, is said to be navigable if it is deep, wide and slow enough for a vessel to pass.
- A two-way traffic channel permits heavy traffic to move faster except when tows are meeting or passing.
- In river navigation, dams are required to sustain an adequate navigation depth.
- Hopper dredges are self-propelled seagoing vessels used primarily for maintenance dredging and progressive deepening by successive passes.
- Dipper dredges are used to excavate hard compacted material and blasted-rock fragments.
- Floodways are used to divert floodwaters into a topographic depression near the river or into a lake or sea.
- The weight of soil at the toe of the slope counterbalances the slope’s upper part’s weight.
- Filters that are used with ripraps must be more porous than the base material.
- A flexible Launching Apron can be laid horizontally on the bed at the foot of the revetment so that when scour occurs the materials will settle and cover the side of the scour hole on a natural slope.
- Gabions may help construct weirs or drop structures in areas where adequate filler material is available.
- Hardpoints are structures that extend short distances into the river channel and are supplemented with a root section.
- Vanes are structures designed to guide the flow of a channel away from an eroding bank line.
- Bendway Weirs are river structures constructed to be a low sill located in a navigation channel bend and designed to control near-bed flow velocities.