Silt and Construction Materials Directorate, Central Water and Power Commission, New Delhi.
The paper relates to the special aspect of the quality of subsoil ater of the area in Rajasthan to come under the command of the proposed Rajasthan Canal Project which was investigated as part of the soil survey work done to assess the agri-irrigational potentialities of that area.
It is brought out that the sub-soil water-table of the area is very deep; it ranges from 55 ft. (16.764 m.) to over 300 ft. (91.44 m.) below ground-level. Except for a small fraction of the wells where the salt content of the sub-soil water can be designated as low to not high, that water in over 93 per cent of the wells is markedly saline. Moreover, while the pH of the sub-soil water ranges generally between 5.9 to 8.4 in about 80 per cent of the wells, the pH of the water ranges between 7 and 8. From the point of view of the salts present in the sub-soil water, sodium chloride is most predominant; others like sodium sulphate, calcium sulphate, calcium bicarbonate, sodium carbonate are present in decreasing proportions in that order generally.
The sub-soil water of the area is shown to be unsuitable for use for irrigation purposes. However, some instances are given in the paper where that water is so employed in that State.
Further scope of investigations with some type of demineralising units to convert the sub-soil saline water to make it fit for potable purpose in colonies on the development projects in that State is indicated.
