Estimation of infiltration rate of a paddy growing area in a micro watershed of Sikkim, India

Abstract

This study aimed to estimate the constant infiltration rates from paddy growing area of a micro watershed located in the hilly state of Sikkim, India. Double ring infiltometer test was used for the field measurement of infiltration rates. The observed infiltration rates were compared with predicted values obtained by Horton, Philip, Kostiokov and Green-Ampt infiltration models. The suitability analysis of models was checked through statistical tools namely coefficient of determination and standard error and the best model was identified for the paddy fields of hill topography. The soil samples were collected for the estimation of soil moisture content, bulk density and soil texture analysis. Soil texture was sandy loam to loamy sand within the micro watershed. The bulk density in the study area varies between 1.25 to 1.53 g/cm³ with an average bulk density of 1.53 g/cm³. Results showed that constant infiltration rate varied from 0.80 cm/hr to 6.02 cm/hr with an average value of 2.55 cm/h for the paddy cultivated fields within the watershed. Results of analysis showed that Kostiokov model is the best fitted model giving a maximum co-efficient of determination and minimum standard error for the paddy growing area of the micro watershed.