Consider the following statements :

1. The concept of Rain Water Harvesting involves high-end expensive technology.

2. Under the National Water Mission (NWM) campaign “Catch The Rain” has been initiated to promote Rain Water Harvesting.

3. ‘Khadins’ and ‘Johads’ are indigenous rainwater storage systems.

4. In the flood plains of Bengal, people developed inundation channels to irrigate their fields.

Which of the statements given above are correct?