Development of a dual permeability model within a hydrological catchment modeling framework: 1D application

Area of Science:

• Hydrology
• Environmental Science
• Soil Science

Background:

• Preferential flow significantly impacts pesticide transport to groundwater, often underestimated in hydrological models.
• Accurate modeling of preferential flow is crucial for assessing pesticide risks and developing effective management strategies.

Purpose of the Study:

• To develop and validate a dual permeability approach within the CMF hydrological modeling framework.
• To simulate pesticide fast transfer in macroporous soils, focusing on water and solute movement.
• To compare the new model's performance against established methods like Hydrus1D.

Main Methods:

• Developed a dual permeability approach in CMF, activating macropore infiltration upon matrix saturation.
• Utilized a transfer function for water flux from macropores to the soil matrix.
• Coupled solute transport (convection-adsorption) to the CMF-dual permeability (CMF-DP) model.
• Validated the model in 1D across four soil types against Hydrus1D.

Main Results:

• The CMF-DP model showed underestimated matrix infiltration but significant macropore infiltration compared to Hydrus1D for most soil types.
• Water flux transfer between macropores and matrix yielded similar results between the models.
• The CMF-DP model requires fewer input parameters, particularly for macropore-matrix exchange.

Conclusions:

• The developed CMF-DP model effectively simulates pesticide transfer in macroporous soils.
• The model presents a computationally efficient alternative with fewer parameters for operational applications.
• Further research can extend this model for large-scale pesticide risk assessment.