4.2 Need, scope and strategies for conjunctive use

The main need in the region is for policies that can counter the trend towards water logging and soil salinity. Under SCARP in Pakistan, designed to overcome this situation, public tubewells were installed to provide vertical drainage (Johnson). However, it has proved difficult to run these tubewells cost-effectively. As a result, recent reversals in policies encourage private investment and control of tubewells. This has led to rapid increase in private shallow tubewells particularly in fresh groundwater areas.

Rapid expansion of private shallow tubewells was also noticed in the Indian north-western region, though following from a different set of policies and reasons. For example, in Haryana only 183 thousand ha were irrigated by tubewells in 1961; these increased to 986 thousand ha by 1984-85 (Gangwar and Panghal). Infact, it has been argued that the large scale development of tubewell irrigation in northern canal command areas could be sustained despite the gross inadequacy of rainfall in the region mainly due to added groundwater recharge from canal irrigation (Sawant, 1985).

In all these areas, the essence of the problem is how to regulate the private pumping of groundwater in (i) brackish/saline areas including those areas where fresh water is underlain with layer of saline water, (ii) areas with fresh water, where draft is greater than the recharge and (iii) areas with fresh groundwater and with supporting infrastructure of surface irrigation system. In the third category of areas, judicious planning would be required to achieve conjunctive use of both surface and groundwater. It would be interesting to examine ways to replicate the Chinese experience in conjunctive use in which farmers in the upper canal reaches have increased their reliance on groundwater, while those in the lower reaches rely on a system of ponds and reservoirs (Kramer).

In areas with saline groundwater, further extension of surface irrigation raises the water table and brings the salts to root-zone level. Vertical drainage through private tubewells has major limitations in such areas for it is not possible to irrigate with wells without the treatment of groundwater. In Pakistan and India, private tubewell development has taken place almost entirely in areas overlying "fresh" groundwater. In Pakistan's Punjab, however, water is never absolutely fresh or saline; groundwater quality, in fact, varies over a wide range of values for standard quality indicators (Johnson). Moreover, vertical drainage is, perhaps, not a long term solution to the accumulation of salts in the topsoil, since these salts are not removed from the system when water is applied to farmers' field.

Gangwar and Panghal in their paper refer to several cost effective technologies developed by the Central Soil Salinity Research Institute, Karnal, for overcoming salinity and alkalinity problems. It was also brought to the notice that in Haryana, experiments are conducted to use saline/brackish water through drip or sprinkler irrigation method for protective purpose. This is followed by irrigation with good water at critical stages of crop growth. These technologies are yet to be applied in field on a significant scale and operational constraints and institutional requirements are to be identified.