Consider the following statements regarding cross regulators and distributary head regulators.

1) Distributary head regulator controls the supply and entry of silt in the offtaking channel.

2) Distributary head regulators effectively regulate the entire canal system.

3) Cross regulators help in absorbing fluctuations in various sections of the canal system and closing the supply in the downstream of parent channel for the purpose of repairs and construction works.

4) Cross regulator serves as a meter for the measurement of discharge entering the off taking channel. 

Which of the following statements are correct ?