CS(AR)-7/2000-2001 : Effect of Forest cover changes on sediment yield of Upper Indrāvati Reservoir catchment Orissa

Abstract

The natural process like erosion in the catchment area, movement of sediment and its deposition in various parts of reservoir require careful consideration in the planning of major reservoir projects. In recent years, denudation of catchment through human activity by way of agriculture, deforestation, extensive grazing etc. has been progressively accelerating soil erosion and disturbing solid-liquid equilibrium in the river catchments. The silt, which gets deposited at different levels, reduces the storage capacity of reservoir. Reduction in the storage capacity beyond a limit prevents the reservoir from fulfilment of the purpose for which it is desired.

Periodic sediment yield provides vital information on the rate of soil erosion and changing land use pattern in the catchment and therefore forms the basics of planning, designing and maintaining water resources projects in a river basin as well as for preservation of the catchment echo system.

Upper Indrāvati reservoir, on the Indrāvati River in Orissa, India, is a multipurpose reservoir. Land use and Land cover pattern in the catchment demarcated for the year 2000 using multi-temporal Remote sensed data. It is observed that Scrublands, total forest area, Arable Land constitutes 59, 11 and 21 percentage of total catchment area respectively. There is a 3.61 0/0decrease in the area of Scrublands from year 1996 to year 2000 and 0.9 % increase in Arable land. The Others Land Use Category has also has shown an increase of 3.77 %.

Sediment Yield from the catchment is estimated in the range of 2.750 to 4.282 m3/ha/year, using different statistical methods. The maximum of estimated rate is within the design limit of the reservoir.