Waterlogging and Salinity in the Indus Plain: Rejoinder

Most of the points raised by the Panel members, Drs. Roger Revile, Harold Thomas and Robert Dorfman, have been answered in the comment by Dr. Frank M. Eaton. Dr. Nazir Ahmad has further elaborated some of the issues involved. The author will confine his remarks to two basic issues, namely, pumping of water for irrigation purposes in the non-saline high quality ground¬water areas in the Northern Zone of the Indus Plain and provision of horizontal sub-surface drainage facilities in areas where the groundwaters are saline and unfit for irrigation use. The author is happy to note that the Panel members acknowledge the significant contribution made by private tubewells to the productivity of agri¬culture in West Pakistan. The author agrees with the Panel members that private tubewells will be developed mainly in areas that have adequate supplies of high quality groundwater and not in areas where the groundwater is too saline to be applied to land without dilution with canal water. Ina previous article, the author proposed that horizontal sub-surface drain¬age facilities should be provided in the saline groundwater areas [5, pp.387-395]. The Panel members do not agree with this and propose instead deep tubewells for irrigation as well as for drainage purposes. They suggest that with the use of deep tubewells and canal water the salt be flushed out of the root zone and washed downward with recycled pumped water to be stored underground.