INVESTIGATION OF OPTIMAL CELL SIZE FOR SOIL EROSION STUDIES IN SIWALIKS

Abstract

The colossal amount of data required for soil erosion studies can only be studied, processed , and analysed in no other form than the digital one. cell system is generally used for data generation. The cell size influences the economics of input, storage, processing and output of the data in addition to the accuracy of the final product. Keeping above in view the present study has been carried out to investigate the optimal cell size for soil erosion studies in the Siwaliks at different scales. Soil erosion is defined as the wearing away of the land. Agents of erosion are water, wind, ice, gravity etc. and to this list might be added human activities. USLE is an empirical model developed by the US Department of Agriculture to estimate sheet and rill erosion from agricultural lands. USLE is an simple arithmatic relation composed of five factors which influences soil erosion. Remote Sensing techniques can be economically used for data collection to estimate the soil erosion. The following conclusions have been drawn from the study. 1. Accuracy of final results depends on errors in source data, errors during data input, errors in data storage, errors in data analysis and output. 2. At smaller scales details are generalised. Microlevel studies preferably be carried out at 1:50,000 scale. 3. As the cell size decreases accuracy increases by representing local variations, but the volume of data increases in geometrical progression. 4. Categorical accuracy and cost of data analysis are non-linearly related to the cell size. 5. From the view point of achieving the maximum accuracy with minimum cost, the optimal cell size for soil erosion studies at 1:250,000 scale is 4 mm (on the paper) whereas at 1:50,000 scale it is 3 mm (on the paper) in the Siwaliks.