A tile drain is laid below a cropped land to remove excess irrigation water. The drainage coefficient of this drain is usually expressed as:

Which of the following statements (S1, S2, and S3) pertaining to the development of irrigation and its impacts is/are correct? S1: It increases food production. S2: It improves groundwater storage in the irrigated command area through deep percolation. S3: It increases the tendency to adopt mixed cropping.

In border strip flood irrigation, the optimal time of ponding or water application is estimated primarily on the basis of: