Characterization of the Temporal Evolution of Soil Hydraulic Properties Under Anthropomorphic Conditions 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 alter the hydrodynamic behavior of the soil (Gaillard et al., 2007; Bodner et al., 2013). Today, advances in the field of tomography imagery allow the study a number of physicals processes of soils especially for the transport of colloidal particles (Gaillard et al., 2007) and consolidation processes (Pires et al, 2007). The main objective of this work is to evaluate the temporal evolution 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, pressure head, input and output water flow, tracer monitoring (KBr and ZrO₂) and tomographic analyses have been used to quantify the temporal evolution of the soil hydraulic properties. The results showed that the drainage and recharge accelerated cycles have a high effect on soil hydraulic properties evolution in most of the time reducing the soil drainage capacity. Knowledge about the mechanisms responsible for this anthropic-induced soil alteration is capital for water management in intense agricultural systems, such as cranberry farms. 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.

References:

Bodner, G., P. Scholl and H.P. Kaul. 2013. Field quantification of wetting–drying cycles to predict temporal changes of soil pore size distribution. Soil and Tillage Research 133: 1-9. doi:http://dx.doi.org/10.1016/j.still.2013.05.006.

Gaillard, J.-F., C. Chen, S.H. Stonedahl, B.L.T. Lau, D.T. Keane and A.I. Packman. 2007. Imaging of colloidal deposits in granular porous media by X-ray difference micro-tomography. Geophysical Research Letters 34: L18404. doi:10.1029/2007GL030514.

Pires, L.F., O.O.S. Bacchi and K. Reichardt. 2007. Assessment of soil structure repair due to wetting and drying cycles through 2D tomographic image analysis. Soil and Tillage Research 94: 537-545. doi:http://dx.doi.org/10.1016/j.still.2006.10.008.