Modelling uncertainties in the diffusion-advection equation for radon transport in soil using interval arithmetic.

Area of Science:

• Geophysics
• Environmental Science
• Earthquake Science

Background:

• Radon transport modeling in the Earth's crust is crucial for understanding pre-earthquake geophysical changes.
• Deterministic advection-diffusion models are commonly used, but parameter uncertainties require investigation.
• Quantifying uncertainties in transport parameters is essential for accurate interpretation of experimental data.

Purpose of the Study:

• To investigate the impact of interval uncertainties in radon transport parameters on modeling.
• To combine interval uncertainties with the advection-diffusion equation for soil matrices.
• To compare interval arithmetic predictions with classical deterministic models.

Main Methods:

• Application of interval arithmetic to model radon transport with uncertainties in soil diffusivity and advection velocity.
• Comparison of predictions from the interval uncertainty model with a classical deterministic model.
• Case study using steady-state radon flux measurements at the soil surface.

Main Results:

• The interval uncertainty model provides a framework for analyzing parameter uncertainties in radon transport.
• Predictions from the interval model offer insights into the range of possible outcomes.
• The model successfully detected low-level advection processes by applying uncertainty bounds to observed concentration data.

Conclusions:

• Integrating interval uncertainties into radon transport models enhances the understanding of geophysical processes.
• This approach improves the sensitivity to detect subtle changes, like low advection, prior to earthquakes.
• The model demonstrates practical applicability in analyzing real-world radon flux measurements.