River Vanes

River Vanes

Background

The River Waal is one of the larger river branches that make up the

Rhein River delta system. The river supports commercial navigation from

the Port of Rotterdam into Germany and France. The river 's bedload is

primarily sand, with most of the shoaling occurring in bendways or mid-

channel in the form of sand waves. Several nondredging techniques have

been used to control shoaling in the river. The techniques include: armor-

ing the outside slope to force flow into the interior bank; groins, both

emergent and submerged, to train flow to the centerline of the channel;

and submerged, midstream vanes that reduce spiral flow near the river

bottom to diminish scour on the outside bank and decrease deposition on

the inside bank. Many of these techniques have been used in river sys-

tems throughout the United States except for the mid-river vanes (see

below).

Technology

The vanes are sheet-pile driven into the river bottom to help control the

flow lines of the river, stabilizing the bendway by reducing the tendency

of the river to erode the outside bank while depositing on the inside bank.

Spacing, elevation off the bottom, and depth of burial are all dependent on

river dynamics and desired outcome. Approximately 1 million m3 of ma-

terial is dredged from the river each year. This amount is estimated to be

one half to one third the amount required for removal to meet authorized

dimensions if nondredging techniques were not used.

Potential applications

River vanes may be cost-effective for high-velocity rivers such as the

Columbia or the Mississippi. Vanes could reduce shoaling through bend-

ways; however, underkeel clearance must be considered for navigation

safety. Interviews with Rijkswaterstaat staff indicate that safety issues

and navigation concerns have been studied and proper clearance require-

ments developed.

Company/Organization(s): Access restricted to U.S. Army Corps of

Chapter 4

Detailed Evaluations