Detached and transported soil particles, due to action of water or wind deposite at downstream side of river, watershed and any other watershed structure leads into degradation of the land and ecology. The observed sediment yield of the Sonwal watershed in 200203 was 5.88 t/ha/yr. However, it was found 10.22 t/ha/yr with an increase of 4.34 t/ha/yr in 200809. The estimated sediment yield of the watershed for the year 200809 was found to be 14.82 t/ha/year with per cent change in observed and estimated sediment yield, 45. The area under waste land is increased by 15.55 per cent, agriculture area increased to a very less extent 0.18 per cent and forest land is reduced by 2.69 per cent, therefore the increased sediment yield was observed to the extent of 4.34 t/ha/yr (73.80%) in six years i.e. from 200203 to 200809. To reduce the rate of increase of sediment yield, the agriculture area needs to be increased by decreasing the wastes land besides, the watershed development program need to be implemented effectively to reduce the sediment yield or soil loss.

Keywords: Sediment Yield; Soil and Water Conservation.