River infrastructure is the fixed set of landings, docks and channel marks that turns a river from a hazard you read each time into a route others can use: a landing is a graded bank, a floating dock rises and falls with the water on a hinged ramp, a pile dock suits only a river whose level is nearly constant, and the channel is marked so everyone reads the same signs. Choose by how far the water level swings: with a 2 m swing, a ramp at 1 in 6 is 12 m long, and a floating dock avoids the length altogether.
Part of River Navigation & Ferry Systems
River infrastructure is the built structures along a navigable river: landings, docks and mooring points, and the marks that show the channel.
The River’s Level Decides The Design
A landing that works in summer is under water in spring, and a dock fixed at the spring level is dry in summer. Before choosing any structure, find how far the river’s level moves, from Historical Flood Marks and from your own measurements across a season (see Flood Planning). The carrier gives three kinds of structure: a simple landing, a floating dock and a pile dock; each has a range of water-level change it can take.
As river traffic increases, the carrier says to mark the navigable channel with buoys, daymarks, range markers and mile markers, and to establish conventions and make them known, because a marking system only works if everyone understands it.
What You Need
- A record of water levels, or a flood mark and a low-water mark
- A site with firm banks, away from the outside of a bend where the bank erodes
- Materials: gravel and flat stones, logs, sealed drums or pontoons, posts, rope
- Hand tools and a means of moving heavy timber
- A survey of the bank slope (see Surveying Techniques)
Method: Choose And Build
Step 1: Measure the swing of the water level, from lowest to highest in a year.
Step 2: Choose the structure. Small swing: a pile dock or a fixed ramp. Large swing: a floating dock on a hinged ramp, or a long graded landing.
Step 3: Build in summer low water, the carrier’s best season for building and repairing docks, landings and cable anchors.
Step 4: Add moorings: bollards or rings, at least two at every landing (see Landing & Dock Construction).
Step 5: Mark the channel and publish the conventions (see Channel Marking & Aids).
Worked Example: Ramp Length For A Moving River
If the river’s level swings by 2.0 m (an assumed value) and the ramp slope is 1 in 6 (a choice for a cart or animals), the ramp must be 2.0 × 6 = 12 m long to reach from the low-water to the high-water line. At 1 in 8 it is 16 m. A floating dock on a hinged ramp avoids this length: the dock follows the water, and only the hinged ramp between dock and bank changes its angle. The same 2.0 m swing then changes the ramp’s slope but not its length. A pile dock built for the high level would stand 2.0 m above the low-water line, and one built for the low level would be under 2.0 m of water at the flood.
Common Mistakes
- Building a fixed pier for the summer level — the spring flood carries it away.
- A landing on the outside of a bend — fast water and a cut bank.
- Moorings placed to one side only — two points, at least.
- Marks no one knows how to read — publish the convention.
Safety
Landings are where people fall in
Wet planks, ramps and mud are slippery, and a boat moving against a dock can crush a hand or a leg. Keep the walking surface gripped, rail the dock edge where animals walk, and never stand between a boat and the dock. In cold water, see Safety & Capsizing Recovery.
What’s Next
- Learn next: Landing & Dock Construction — the structures in detail
- Combine with: Channel Marking & Aids — the marks that go with them