SON CANALS 79
The work was greatly facilitated by the presence of excellent building
stone a few miles frog the site. Scouring sluices were provided at each
flank and at the centre. Those at the centre have since been filled ttp.
The flank sluices serve to maintain clear channels in front of the canal
head sluices, and they facilitate the regulation of the height of the water
in the pool above the weir. The vents are operated, by means of
shutters zo feet G inches in length, on a system devised by the late
Mr. C. Fouracres, by which the shock of the up-stream shutter when
rising is taken by hydraulic tubular struts. The system has worked
well, and there is a very complete control of the river even when it is
in moderate flood. The total cost of the anicut, which was finished
in r875, amounted to about r5 lakhs.
The total length of the main< çanals is z t8 miles, of the branch canals
r4q miles, and of the distributaries r,zr7 miles. The western main
canal supplies the Arrah, the Buxar, and the Chausâ canals, which all
branch off within the first rz miles. The main canal is continued for
a total distance of zz miles, as far as the grand trunk road, z miles
beyond Sasarâm. Its prolongation for a farther distance of 5o miles
to the frontier of the District, towards Mirzâpur, was commenced as
a relief work during the scarcity of 1874-g, but never completed. The
chief engineering work is the siphon-aqueduct of twenty-five arches,
by which a formidable hill-torrent, called the Kao, is carried under the
canal: The Arrah canal branches off at the fifth mile, and follows
the course of the Son for 3o miles, when it strikes northwards, running
on a natural ridge past the town of Arrah, and finally falls into a branch
of th'e Ganges after a total course of 6o miles. It is designed for navi-
gation as well as irrigation, but no permanent communication has been
opened with the main stream of the Ganges. To allow #'or a total fall
of t8o feet, r3 locks have been constructed. Besides four principal
distributaries, the main offshoots are the Bihiyâ canal, 3o miles long,
and the Dumraon canal, 4o miles. The Buxar canal leaves the main
western canal at its twelfth mile, and communicates with the Ganges
at Buxar, after a course of 55 miles; it also is intended for navigation.
'The total fall is t59 feet, which is facilitated by twelve locks. Gayâ
and Patna Districts are served to a smaller extent by the eastern main
canal, which was originally intended to run as far as Monghyr, but at
present stops short at the Pimpün river, a total length of only 8 miles.
`Che Patna canal leaves the main canal at the fourth mile, and follows
the course of the Son till it joins the Ganges at Dïgha, between Banki-,
pore and Dinapore. Its total length is 7q miles, of which 43 miles lie
within the District of Gayâ, and 3G in Patna.
The area irrigated in igog-4 was 7qo square miles. In a9oz-g the
net revenue was 874 lakhs, giving a return,of 3~z7 per cent. on the
capital expenditure; while in t9o8-4 the receipts amounted to Iâ~z4
|
![[Digital South Asia Library]](/graphics/thirdlevel.gif)
