Field evaluation of the pedostructure-based model (Kamel®)

This study involves a field evaluation of the pedostructure-based model Kamel® and comparisons between Kamel® and the Hydrus-1D® model. Both models are commonly named 1D – soil water models because they simulate the flux of water within the soil, related to climate conditions variation and water uptake by roots. The field site used in the investigation is within the Upper Cedar Creek Watershed (UCCW) in northwestern Indiana, USA. A description of both models has been made, emphasizing on the physical principles on which the pedostructure parameters for Kamel® were calculated or estimated using usual pedotransfer functions according to a methodology explained in the article. Sensitivity analysis for the pedostructure parameters of the Kamel® model showed that values for Kbs (slope of shrinkage curve for basic water content), VA (specific volume of pedostructure at dry state) and αL (hydraulic conductivity coefficient for high range of macropores) were the most sensitive parameters of the soil medium for Kamel® model input. The calibration for Kamel® and Hydrus-1D® was carried out for a 15 day time period for determining the non-measured parameters. 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 field site, but performance of Kamel® was superior to Hydrus-1D® for deeper layers. However the lack of information about the internal organization of the soil in situ, like thickness of horizons, roots repartition, accepted by Kamel®, does not permit to make a complete validation of the model. We only show here that Kamel® can do as well as Hydrus-1D®, a more known and experimented soil water model; however, Kamel® is more promising in terms of ability to couple dynamics of the internal hydrostructural state of the soil medium to the external climatic conditions and the biological processes in the critical zone.

► Validation Kamel, a model that simulates water flow using pedostructure parameters. ► Kamel and Hydrus-1D soil moisture in good agreement with measured at 5 and 20 cm layers. ► Performance of Kamel was superior to Hydrus-1D for deeper layers (40 and 60 cm). ► Most sensitive parameters for Kamel are Kbs, VA and αL.