04 Vadose Zone Physics

04-02 Soil Water Retention

Soil water retention curves, matric potential, capillarity, and constitutive relationships linking moisture content and pressure head.

Contents

Index Description
04-02-001 Soil Water Retention Module

04-02-001Soil Water Retention Module

Type: Streamlit app Time: 2-4 hours
Soil Water Retention Module

Figure 1: The interactive plot of the soil water retention curve with the Van Genuchten equation. (Screenshot)

This interactive module introduces the fundamental concepts of soil water retention in unsaturated soils and provides a structured, hands-on exploration of the van Genuchten–Mualem formulation, one of the most widely applied models in vadose zone hydrology.

The module explains how water is retained in soils under unsaturated conditions, emphasizing the physical meaning of capillary pressure, pore-size distribution, and effective saturation. Users interactively explore how key model parameters (θᵣ, θₛ, α, n) control the shape of soil water retention curves and influence hydraulic behavior.

Designed as a step-by-step learning resource, the module supports both first-time learners and users seeking to refresh or deepen their understanding. Interactive visualizations are combined with guided exercises that promote conceptual understanding, parameter interpretation, and practical model calibration.

Module Structure

📚 Theory Introduces the physical basis of soil water retention, including capillarity, surface tension, and the conceptual background of the van Genuchten–Mualem model.

📈 SWRC Interactive Enables real-time exploration of how individual model parameters affect soil water retention curves.

📊 SWRC in Comparison Facilitates comparison of retention behavior across different soil textures (e.g., sand, loam, silt).

🧪 Exercise 1 Focuses on fitting the van Genuchten model to measured retention data and interpreting parameter sensitivity.

🧪 Exercise 2 Uses synthetic datasets to identify soil types and assess implications for agricultural use and flow processes.

LAUNCH RESOURCE

Detail Value
URL gwp-soilwaterretention.stre… · open app
Author(s) Oriol Bertran (Universitat Politècnica de Catalunya (UPC)); Daniel Fernàndez-Garcia (Universitat Politècnica de Catalunya (UPC)); Thomas Reimann (TU Dresden); Eileen Poeter (Colorado School of Mines)
Keywords Unsaturated zone, van Genuchten, soil water retention, capillary forces, Mualem
Fit For self learning, exam preparation
Prerequisites Basic Hydrogeology, soil properties

Streamlit app details

Detail Value
Multipage app yes – approx. 10 page(s)
Interactive plots 8 interactive plot(s)
Assessments included 68 question(s)
Videos included 3 video(s)

Images

The theory section of the SWR module with interactive illustration.

Figure 2: The theory section of the SWR module with interactive illustration. (Screenshot)