TN-28 : Study of soil moisture using neutron probe

Abstract

The fundamental importance of maintaining soils to meet the food and fiber needs of a burgeoning world population merits the attention and concern of all people. Erosion of soil by water poses an increasing threat as needs for food, fiber production and space for social and economic necessities of a growing population add, pressures to our nation's land resources. The soil loss prediction techniques have developed over many years as understanding of the erosion process expanded and increasingly more erosion research was conducted. Early estimates were primarily qualitative in nature and illustrated that some cultural practices differed in their ability to control soil erosion. Initially, equations were developed to describe soil loss using a single independent variable. These single factor equations were for local situations were developed as more data became available and researchers were better able to describe contributing factors. These analyses culminated in the equation most widely used today for soil loss prediction the Universal Soil Loss Equation (USLE). The USLE is a highly useful tool for predicting sheet and rill erosion under various conditions of land use and management. Recent investigations have focused on defining the parameters of the USLE for a greater range of conditions. Considerable work continues to define the soil erosion process and, hence, eventually predict soil loss, from a physical basis in contrast with the predo7inantly empirical soil loss predictions of the past and present.

The Universal Soil Loss Equation was applied to the Chaukhutia catchment of Ramganga River. The Chaukhutia watershed is located between 29°46'15" to 30°6' N latitude and 79°12'15" to 79°31' E longitude in Almora and Chamoli districts of Uttar Pradesh under Ranikhet sub-division of Ramganga reservoir catchment. The area of the watershed is 452.25 sq km with mean length of 30 km and width of 15 km. The maximum elevation of the watershed is 3114.14 m above M.S.L. and the minimum elevation at Chaukhutia is 929.00 m. The average annual total precipitation in the area is 1466 mm which varies from 1205 mm to 1773 mm at different locations. The methods of determination of different parameters and results of universal soil loss equation for predicating soil loss from the above basin are presented in the report.