Vasquez, Vicente5; Thomsen, Anton Gårde6; Iversen, Bo Vangsø6; Ringgaard, Rasmus4; Schelde, Kirsten5
1 Department of Agroecology, Science and Technology, Aarhus University2 Department of Agroecology - Climate and Water, Department of Agroecology, Science and Technology, Aarhus University3 Department of Agroecology - Soil Physics and Hydropedology, Department of Agroecology, Science and Technology, Aarhus University4 Institut for Geografi og Geologi5 Department of Agroecology - Climate and Water, Department of Agroecology, Science and Technology, Aarhus University6 Department of Agroecology - Soil Physics and Hydropedology, Department of Agroecology, Science and Technology, Aarhus University
Quantifying recharge to shallow aquifers via soil deep percolation is needed for sustainable management of water resources. This includes modeled predictions to address the effects of climate change on recharge. Different methods to estimate soil deep percolation exist but few comparisons among them have been reported. To compare among methods, one year of four large-scale lysimeters drainage (D) was evaluated against modeled soil deep percolation using either profile soil moisture, bromide breakthrough curves from suction cups, or measured soil hydraulic properties in the laboratory. Measured volumetric soil water content (q) was 3-4% higher inside lysimeters than in the field probably due to a zero tension lower boundary condition inside lysimeters. D from soil hydraulic properties measured in the laboratory resulted in a 15% higher evapotranspiration and 12% lower drainage predictions than the model calibrated with field measured q. Bromide (Br) breakthrough curves indicated high variability between lysimeters and field suction cups with mean Br velocities at first arrival time of 110 and 33 mm/d, respectively. D was 520 mm/yr with lysimeters, 613 mm/yr with the calibrated model using field q, and 572 mm with the laboratory measured soil hydraulic properties. In conclusion, lysimeters presented the lowest D and can be considered as a lower bound for D; whereas either laboratory measured soil hydraulic properties or models calibrated with profile soil moisture yielded larger D values.
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ASA, CSSA and SSSA International Annual Meetings, 2012