Characterization of Spatiotemporal Variability of Soil Hydraulic Properties Under Drainage and Recharge Cycles By X-Ray Tomography.

The installation of drainage systems may cause anthropic-induced evolution of soil profile. In fact, natural consolidation (drainage and recharge cycles and flooding), filtration and clogging soil pores by colloidal particle accelerated by water management will reduce drainage capacity of the soil. X-ray tomography can be used to characterize soil hydraulic properties at a fine scale and to study a number of physicals processes of soils especially for the transport of colloidal particles and consolidation processes. The main objective of this work is to analyze spatiotemporal variability of hydraulic properties of a sandy soil during repeated drainage and recharge cycles using a medical CT-scan. A soil columns laboratory experiment was setup in fall 2013 and 2014, pressure head, input and output water flow, tracer monitoring (KBr and ZrO₂) and tomographic analyses have been used to analyze the spatiotemporal variability of the soil hydraulic properties. The results showed that the drainage and recharge accelerated cycles have a high effect on soil hydraulic properties evolution reducing the soil drainage capacity. Knowledge about the mechanisms responsible for this anthropic-induced soil genesis is important for water management in agricultural systems. This information may allow us to predict soil evolution according to soil texture, drainage system design and water management, in order to better anticipate and control their future negative effects.