Notwithstanding the large number of streams, the depression of their channels and height of their banks render them for the most part unsuitable for the purposes of irrigation, - which is conducted by means of jhils and tanks.
The other, short and broad, and in great part occupied by swamps and jhils, separates the Garo, Khasi and Naga hills from those of Tippera and the Lushai country.
Numerous shallow ponds or jhils mark the former beds of the shifting rivers.
These jhils have great value, not only as preservatives against inundation, but also as reservoirs for irrigation.
The jhils supply the villages with wild rice, the roots and seeds of the lotus, and the singhara water-nut.