Water and Energy Abstracts

Three different models, the Modified Green-Ampt-Quadratic Approximation (MGA-QA), the Modified Green-Ampt-Taylor Approximation (MGA-TA), and the Modified Green-Ampt-Numerical Solution (MGANS), are considered to investigate their performances in simulating two stage infiltration process under steady rainfall. The comparative analysis is performed for various soil textures to investigate the infiltration characteristics in various soil types under similar rainfall pulse and initial surface conditions. Results reveal that the maximum error for the MGA-QA is 7%, while the maximum error for the MGA-TA is 4.5% as compared to solutions obtained from the MGA-NS model. It is also observed that the MGA-TA model gives less error for coarse textured soils, while the MGA-QA model for fine textured soils. As solutions can be obtained explicity using the MGA-QA and the MGA-TA models, these two models may be used in practice without loss of much accuracy for point estimation in case of short-time periods. However, solutions obtained from the MGA-QA and the MGA-TA models can be utilized as initial fesible solutions for the MGA-NS model to reduce the number of iterations involved in obtaining numerical solution. The error may be more for larger time periods and it may be significantly high when spatial integration is carried out in a drainage basin/an irrigation command of dominant spatial heterogeneity in soil properties and rainfall events. The MGA-NS model may be preferred in such cases for the inclusion in hydrological models to address increasingly complex real life water resources problems.