Jumna, a river of Hindostan, and the principal tributary of the Ganges. It rises in Gur-whal, near the S. base of the Himalaya, in lat. 31° N, lon. 78° 32' E. at the foot of a group of hills called the Jumnotri peaks, near which it receives the overflow of several hot springs. It is here a violent torrent, having for 16 m. an average descent of 314 ft. per mile. After a S. W. course of about 60 m., during which it is joined by several large mountain streams, it receives the Tonse in lat. 30° 30', lon. 77° 53'. About 97 m. from its source it enters the plain of Hindostan, flowing S., and divides into several branches. It here becomes navigable by rafts. After passing Delhi, where it is crossed by a bridge of boats, its general course is S. E. It joins the Ganges at Allahabad, 619 m. below Delhi, and 860 m. from its source. In the lower part of its course the Jumna is sometimes 2 or 3 m. wide. Its banks are rocky and precipitous, and its current is rapid. Navigation is attended with much difficulty, but many of the most serious obstructions have been removed, and vessels can now ascend to Calpee. Its principal affluents are the Chumbul, Sinde, Betwa, Cane, and llindaun.
Delhi, Agra, Muttra, Etawah, Calpee, and Allahabad are the most important places on its banks. - There are two extensive systems of irrigation connected with the Jumna. The western Jumna canal comprises the ancient canal of Feroze Shah and the Delhi canal, on the right bank of the river, which were restored between 1823 and 1843 by the British authorities, who built many additional branches. This system waters the country along the western bank of the Jumna, from a point called Hathni Kund, just north of the 30th parallel, down to Delhi. The aggregate length of its main lines is 445 m., and in 1866-7 the area irrigated comprised 447,171 acres, in 797 villages. The net receipts from water rates in 1871-2 were £74,518, being 26 per cent. on the outlay for construction. The eastern Jumna canal irrigates a district about 120 m. long and 15 m. broad on the left of the river, and extends from a point in the main stream near the head of the western system, southward to Delhi, flowing for 40 m. between embankments, at a height of from 6 to 12 ft. above the general level of the land. It was projected by Shah Jehan, between 1628 and 1659, but had long been disused when it was restored by English engineers in 1830. The main channel is itself 130 m. long, and feeds 619 m. of distributary streams.
The area of irrigation in 1871-'2 was 192,749 acres, and the net revenue £32,881, being 16.6 per cent. on the outlay.