Study the following statements:

(i) Levees are constructed parallel to the river flow.

(ii) Spurs are constructed parallel to the river flow.

(iii) Levees are constructed transverse to the river flow.

(iv) Spurs are constructed transverse to the river flow.

The correct answer is:

Concept:

Levees

Levees construction is a method of river training. They are constructed to protect the riverbanks from flooding. It is basically an embankment constructed along the river so that water remains contained in between the levees during flooding.

Effects of levees construction:

• It reduces the width of the river stream, so flow velocity is increased.
• It contains the flood water in between the levees only, which increases the discharge.
• It increases the water surface elevation during flooding.
• It decreases the flood storage as maximum flood water becomes the part of discharge.

Groynes / Spurs: 

• These are the embankment type structures constructed transverse to the river flow.
• They extend into the river from the bank and may also be called transverse dykes.
• They are constructed to protect the bank by deflecting the current away from the bank.
• They train the river to flow along a desired course by attracting, deflecting or repelling the flow.