Drainage water, once thought of as wastewater, is now used in many countries for irrigation. The salinity levels vary, but often the salt levels are higher than those of conventional primary irrigation water sources. Reuse of drainage effluent is important when the supply of good quality irrigation water is limited, and it is also an efficient means of reducing water pollution. The potential disadvantages of such blending are discussed later. Over time, the cropping pattern in this district has changed as the water quality has decreased.
Crops now grown are mostly cotton, barley and alfalfa.
The use of brackish groundwater is reported from Tunisia, India and Israel. De-Malach et al. However, there are specific stretches or locations along the river system where salinity level increases due to hydrologic as well as human-induced activities. In the deltaic region of the Ganges river in West Bengal, which comes under tidal influences, the salinity of the water can rise to greater than 10 times the average salinity of the river. On the other hand, drainage waters are reported to have high salinities.