1879.] Discharge of large Rivers in Assam. 13 
The river at time of measurement was 8 feet above the minimum level 
of the year. The increased section due to this 3 feet rise, is computed to 
be 6,222 superficial feet, and the increased discharge to be 27,359 cubic feet 
per second ; thus the cold weather low-level discharge of the united streams 
is 82,652 cubic feet, sectional area 18,883 superficial feet, mean velocity 4°3 
feet per second. 
To obtain the cold weather low level discharge of the Dihang river it 
is necessary to subtract the Dibang discharge, shown below to be 27,200 
eubie feet per second, and this quantity subtracted from the discharge 
of the united streams will give the Dihang discharge to be 55,400 cubic 
feet per second at minimum level of the year. 
During very high floods the united rivers rise 20 feet, but the cal- 
culations have been made for an ordinary high flood rise of 15 feet which 
gives a discharge of 485,000 cubic feet per second, a sectional area of 
84,000 superficial feet and consequent mean velocity of 5:7 feet per second. 
To obtain the flood discharge of the Dihang river, it will be necessary 
to subtract that of the Dibang river which is shown below to be 122,483 
cubit feet per second, which amount subtracted from the above 485,000 
cubic feet leaves for the ordinary flood discharge of the Dibang river 
362,517 cubic feet per second. 
The next river measured was the Dibang river at one mile above its 
mouth and half a mile below the mouth of the Senseri river. 
The work was done on the 27th March 1878 when the river was 5 
feet above the low level of the year. This river receives a good deal of 
snow-water, from snowy mountains close to the plains. After a hot day 
the river will rise during the night 2 to 3 feet, subsiding during the morn- 
ing. This is not the case in the Dihang river. 
There were 37 soundings taken for the section. At 9 stations ob- 
servations were made for velocity, and there were 116 recorded passages of 
floating instruments. 
The measured discharge was 47,383 cubic feet per second, sectional 
area 10,992, and therefore mean velocity 4:3 feet per second. But at 
time of measurement the river was 5 feet above minimum level of the 
year, and this 5 feet rise has been computed to produce an increased sec- 
tional area of 4,617 superficial feet and discharge of 20,181 cubic feet. 
Thus the discharge of the Dibang river + Senseri river at the low level 
of year is 27,202 cubic feet per second, sectional area 6,375 superficial feet 
and mean velocity 4:2 feet per second. But the Senseri river brings down 
about 1,200 cubic feet, so that the low level discharge volume of the Dibang 
river is 26,000 cubic feet per second. 
During the high floods the river rises 20 feet, but like the Dihang 
computations an ordinary flood of 15 feet has been calculated for, and 
