Question

Which one of the following streambank protection measures is to be adopted where the stream takes to meandering; eroding the banks, and where the cuts are vertical?

• A. Wooden jack series
• B. Groynes or Spurs
• C. Check dams
• D. Brushwood roller

Hint:

Groynes/Spurs = Transverse river training structures deflecting flow away from eroding meandering banks. Check dams = Gully control structures.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
River training and streambank stabilization structures prevent lateral migration and undercut erosion along outer concave meandering riverbanks.

Step 2: Detailed Explanation:
When an alluvial stream meanders, high-velocity thalweg currents impinge against outer concave banks, creating vertical cuts and bank slumping.
Groynes (or Spurs) are transverse deflecting structures constructed projecting outward from the eroding bank into the stream channel.
They deflect the high-velocity erosive current away from the vulnerable vertical bank toward the channel center and induce quiet sediment deposition (silting) along the bank toe.

Step 3: Final Answer:
Thus, the measure to be adopted for meandering streams with vertical cuts is Groynes or Spurs, corresponding to option (B).