Modelling Iniltration in A Large Scale Paddy Field in Malaysia

Abstract

A number of models are available to measure infiltration in agricultural fields; however, their applicability is site specific. It is not easy to choose an adequate model to estimate infiltration at a particular agricultural field. In this study, ten different infiltration models have been used for the estimation of infiltration rate in data scarce Muda Irrigation Scheme, the largest paddy field in Malaysia. The model parameters are estimated from soil characteristics, secondary data and literature. The estimated infiltration rates by the models are compared with the measured infiltration rates in order to assess the suitability of the models in the paddy field of Malaysia. The results show that the infiltration rate estimated by physically based Smith-Parlange nonlinear model is very close to the observed rate. Mean monthly iniltration rate estimated by Smith-Parlange model is 0.098mm with a maximum 0.227mm during December to March and a minimum 0.005mm in May and August. All other methods are found to overestimate the infiltration rate. Though the performance of the models is assessed based on results obtained using limited data and secondary information, it is expected that the research will help select the right model to estimate infiltration, which is highly important for irrigation management especially in paddy fields.