‘The canal, shortly after entering on and skirting the base of the range of hills west of Delhi (the drainage from which crosses over the canal by ancient aqueducts), is finally led directly across the ridge by a channel cut out in the rock, to the depth of about 60 feet at the crest. It then enters the city, and passing through it by an open channel, traverses along another extensive aqueduct into the palace, throughout the whole of which it ramifies, in open or covered water-courses, having outlets to the Jamna, thus permitting the passage of constant streams of fresh water. Similar to these, in the space between the range of hills and the palace, numerous underground channels were led off the the various residences of the nobles, and the divisions of the city, yielding to the whole city and its suburbs a supply of good water, from the open well shafts connected with these underground water-courses, and necessary to admit of their being cleared out.
On a review of the ancient works in Delhi, connected with the canal, money must have been expended with a most lavish hand, to effect what is known; and much is yet hidden in the ruins of the neighbourhood’
On groundwater in the region around 1800:
‘The original and almost sole purpose of the government in under-taking these works appears to have been to convey a large supply of water from the Jamna, for the purpose of irrigation of the crops, 1st, on the lines of country where the natural depth of the wells was so great as to render the cost of irrigation from them so heavy as to impede the improvement of the districts, and delay the resettlement of waste villages, as on the Delhi canal. 2nd, to supply the means of cheap and easy irrigation to districts, as on the Doab canal, where although the wells are not so deep, yet the irrigation from the canal would be so comparatively cheap and easy as to afford the probability of great extension of the benefit : and 3rd, as on FEROZ’s canal, to confer the means of irrigation on districts where from the excessive depth of the wells none was heretofore in use, and to convey a supply of good and wholesome water to a country where generally is it brackish or salt ; in some districts so much so, as to preclude their occupancy, except for a few months grazing in the rains.’