Hydrology of the unsaturated zone

A better understanding of water transfer processes in the unsaturated zone (UZ) of the soil is essential for estimating the runoff/infiltration partition in hydrological models or quantifying groundwater recharge in hydrodynamic models used in hydrogeology.

This course will be mainly based on practical work on soil columns in the laboratory. After a reminder of the equations governing the transfer of water and solutes in the NSA, an initiation to the modeling of transfers in the NSA will be addressed, on the HYDRUS 1D software.

The practical exercises of this course consist in experimenting under controlled conditions (known rain intensity and duration, known dry period, imposed load on the surface, column of sand or reworked soil of known granulometry) the transfer of water in an unsaturated medium and to follow continuously the temporal evolution of the water content and of the water potential at several depths.

• Understand qualitatively the notion of capillarity in the soil and its impact on infiltration processes.
• Understand the concept of water potential and water content in an unsaturated environment and its evolution following a rainy episode or a period of drought.
• Understand the relationship between water content and water potential.
• Estimate the volume of water infiltrated and the useful reserve from the water profiles before and after infiltration.
• Estimate evaporated and drained flux from the zero flow plane method
• Calculation of a simple 1D hydrodynamic flow model in the NSA (with HYDRUS 1D)

Written (final test): 60

Oral (CR of TP) : 40