STUDY OF WATERSHED MANAGEMENT OF KHOLANADONG BASIN IN ASSAM

Abstract

Watershed is a hydrological entity and it refers to a drainage basin of any given outlet. The total catchment area through which water flows into the outlet is of the watershed of that outlet. Watersheds size may range from 10-2,00,000 ha and is named as Major-watershed (50,000-2,00,000 ha), Sub-wateshed (10,000-50,000 ha), Milli-watershed (1000-10,000 ha),Micro-watershed (100-1000 ha) and Mini-watershed (10-100 ha), (Ministry of Agriculture, Government of India, 1987)._x000D_ Watershed concept as a process of economic planning emerged only during late seventies and since then the "soil conservation_x000D_ - pragramme was re-designed as Watershed Management Programme. This acted not merely as a tool for soil erosion and runoff control but as an integrated system for protection and production benefits of the natural resources of the watershed._x000D_ Watershed management is the management of the natural resorces of a drainage basin primarily for the production and protection of water supplied and water based resources, including the control of erosion and floods and the protection of aesthetic values associated with water. It uses the knowledge of hydrology to control flood, prevent erosion, increase the yield of water from the watershed and thereby, provide an adequate supply of water for agriculture, drinking, and commercial purposes._x000D_ In this Dissertation, a case study was made on the management aspects of a watershed in Assam. Rainfall-Runoff analysis have been made to find out the return period from rainfall data and_x000D_ iii_x000D_ dependable runoff from stream runoff data. Also, method of straight line regression is used to check the rainfall-runoff correlation of the watershed._x000D_ Visual interpretation of satellite imagery (F.C.C.) is made to find out the land use pattern of the watershed. Further, land use pattern classification from the satellite' imagery is used in the hydrologic soil cover complex number (S.C.S.) method to determine the peak rate of runoff and runoff volume of the watershed._x000D_ An attempt was made to study the to Tank Model for flood analysis in the watershed._x000D_ Soil loss estimation has been made by using the USLE equation and various parameters of rainfall erosivity factor (R), soil erodibility factor (K), topographic factor (LS), crop management factor (C) and land management factor (P1 are estimated for finding out the average annual soil loss erosion of the watershed. An attempt was also made to use revised USLE (RUSLE) equation, but_x000D_ .- due to non-availability of required data the method could not be applied in the present study._x000D_ Based on the results of various analysis, watershed management measures have been suggested in the watershed for the conservation of soil and water, improved irrigation system and increase in the crop yield.