Set Store by Them
At Sringaverapura near Allahabad in
Uttar Pradesh, India, there exists an extraordinary example
of hydraulic engineering dating back to the end of the 1st century
BC. It comprises three percolation-cum-storage tanks, fed by
an 11 m wide and 5 m deep canal that used to skim the floodwaters
off the monsoon-swollen Ganga.
Water from the canal first entered a silting chamber where the
dirt settled. This relatively clean water was then directed
to the first brick-lined tank (Tank A), then on to Tank B through
a stepped inlet (which cleaned the water further). This tank
constituted the primary source of water supply. Next, the water
passed to a circular Tank C, which had an elaborate staircase.
An elaborate waste weir, consisting of seven spill channels,
a crest, and a final exit, ensured that the excess water flowed
back into the Ganga.