Which of the following methods can be used for river training work ?

Explanation:

River training and River training work:

River training, in its wider aspects, covers all those engineering works that are constructed on a river, so as to guide and confine the flow to the river channel, and to control and regulate the river bed configuration, thus ensuring safe and effective disposal of floods and sediment loads. Stabilising and training the river along a certain alignment with a suitable waterway is, therefore, the first and formost aim of river training.

Objectives of River Training Works:
The river training works may serve the following objectives or advantages :

1. To prevent the river from changing its course and to avoid outflanking structures like bridges, weirs, aqueducts, etc.
2. To prevent flooding of the surrounding countries by providing a safe passage for the flood waters without overtopping the banks.
3. To protect the river banks by deflecting the river away from the attacked banks.
4. To ensure effective disposal of sediment load.
5. To provide minimum water depth required for navigation.

Methods of River Training Work:

1. Marginal embankments or Levees.
2. Guide banks.
3. Groynes or Spurs.
4. Artificial cut-offs.
5. Pitching of banks and provision of launching aprons.
6. Pitched islands.
7. Miscellaneous methods, such as Sills, Bandalling, etc.

Hence option (4) is the correct answer.