HYDROLOGICAL SOIL CLASSIFICATION -A FUZZY APPROACH

Abstract

Hydrologic response of an area is influenced by soil characteristics of that area. Hydrological Soil Classification (1-ISC) refers to a group of soil series that can be considered homogenous in respect of soil characteristics that influence the runoff. The Hydrological Soil Classification is required for a spectrum of hydrologic applications by agriculturists, engineers and soil conservationists. The main soil parameters considered for the hydrological soil classification are effective depth, soil texture, clay percentage, and infiltration. It has been observed that generally uncertainty prevails in various classification approaches. In the present study hydrological soil classification has been carried out using Fuzzy Logic. Fuzzy classification deals with approximate modes of reasoning. Its chain of reasoning is short and everything in it, is a matter of degree. This degree is represented by membership functions. This function can be generalized such that the values assigned to the elements of a set fall within a range of O to 1. During this work, it has been observed that while using Soil Conservation Services (SCS) approach for Hydrological Soil Classification, it is difficult to draw definite conclusions. While Maximum Likelihood Classifier (MLC) yields a definite group but it assumes soil boundaries to be crisp. This assumption is generally not valid in nature. To remove the uncertainty present in the classification, Fuzzy Maximum Likelihood Classifier (FMLC) approach was used. For this membership functions for various properties of the soil were generated in the MATLAB (Ver.5.1.0421) environment and these were incorporated for soil classification. iii