ARS | Publication request: Field Evaluation of the Pedostructure-Based Model (Kamel®)

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 4, 2012
Publication Date: N/A

Interpretive Summary: Water is an important component of the environment’s sustainability and responsible for the survival of flora and fauna on Earth. For example, water is needed to irrigate crops for better yield; however, water is the major transport mechanism for nutrients and contaminants through soil. The present investigation was carried out at Purdue University in collaboration with the USDA, Agricultural Research Service, National Soil Erosion Research Laboratory, West Lafayette, USA. A field site within the Upper Cedar Creek Watershed of northeastern Indiana, USA with varying soil texture was selected to compare soil water flow simulations using Hydrus-1D and Kamel models. The pedostructure parameters for the Kamel model were estimated using the pedotransfer function Kamel soil. Sensitivity analysis of Kamel showed that values of Kbs (slope of shrinkage curve for basic water content), Va (volume of pedostructure at dry state) and AlphaL (coefficient of high range of macropores) were the most sensitive parameters for Kamel model input. The calibration for Kamel and Hydrus-1D was carried out for a 15 day time period prior to the 5-month simulation run. Both models were found to be in good agreement with measured water content at the 5 and 20 cm layers for the site, with performance of Kamel being superior to Hydrus-1D for deeper layers. It is recommended that further sites be validated for Kamel to determine which parameters could be improved. The use of Kamel® should provide a better understanding of soil hydrostructural characterization and interactions between types of soil structure and water, air and biogeochemical processes.

Technical Abstract: This study involves a field evaluation of the pedostructure-based model Kamel and comparisons between Kamel and the Hydrus-1D model for predicting profile soil moisture. This paper also presents a sensitivity analysis of Kamel with an evaluation field site used as the base scenario. The field site used in the investigation is within the Upper Cedar Creek Watershed in northwestern Indiana, USA. Measured soil moisture data were obtained by frequency-domain reflectometry (FDR) sensors permanently installed in a 2.23 ha no-till agricultural field at depths of 5, 20, 45, and 60 cm. Clay content of the field soil varied between 20 to 37% depending on soil depth. The pedostructure parameters for Kamel were estimated using a comparison tool named Kamelsoil. Sensitivity analysis of the Kamel model showed that values for Kbs (slope of shrinkage curve for basic water content), Va (volume of pedostructure at dry state) and AlphaL (coefficient of high range of macropores) were the most sensitive parameters for Kamel model input. The calibration for Kamel and Hydrus-1D was carried out for a 15 day time period prior to the 5-month simulation run. The calibrated parameters were used for validation of both models for the field site. Both models were found to be in good agreement with measured water content at the 5 and 20 cm layers for the site, with performance of Kamel being superior to Hydrus-1D for deeper layers. Both models poorly simulated crop water requirement and water uptake rates during the simulation period.