[M-GI30] Near Surface Investigation and Modeling for Groundwater Resources Assessment and Conservation

[MGI30-01] Monitor the clogging evolution and infiltration process in a meso-scale lysimeter

★Invited Papers

*Shao-Yiu Hsu¹, Jui-Hsiang Lo¹, Qun-Zhan Huang¹, Yi-Zhih Tsai¹, Jung-Dung Lee¹ (1.National Taiwan University)

Keywords:effective hydraulic conductivity, old-new water interaction, soil temperature

In paddy fields or bioretention ponds, clogging occurs when surface water carrying suspended fine grains infiltrates into soils and forms a low permeability soil layer. The clogging layer significantly reduces the infiltration rate and could induce unsaturated zones and preferential flows. In this study, based on Darcy's law for layered soil, we developed a simple 1D equation to show the relationship between the clogging location and the soil water pressure head under different boundary conditions. In a vertical 1D domain, the soil water pressure response head to a decline in the adjacent groundwater level can indicate the occurrence and location of the clogging layer, even the unsaturated zone induced by the clogging layer. We analyzed a series of pressure data measured via a tensiometer installed in a meso-scale lysimeter during steady infiltration experiments under different clogging conditions. The data revealed the clogging development at the bottom of the lysimeter and its influence on the effective hydraulic conductivity evolution. In addition, we performed the unsteady infiltration experiments in the lysimeter (single layer) under flooding and uniform rainfall boundary conditions. The changes in water contents and soil temperatures at different locations were measured to show the infiltration front and old-new water interaction. The results show that the infiltration front was mainly comprised of old water, and its velocity could be increased due to air compression.