Final published version
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Following tracer through the unsaturated zone using a multiple interacting pathways model
T2 - Implications from laboratory experiments
AU - Scaini, A.
AU - Amvrosiadi, N.
AU - Hissler, C.
AU - Pfister, L.
AU - Beven, K.
PY - 2019/7/9
Y1 - 2019/7/9
N2 - Models must effectively represent velocities and celerities if they are to address the old water paradox. Celerity information is recorded indirectly in hydrograph observations, whereas velocity information is more difficult to measure and simulate effectively, requiring additional assumptions and parameters. Velocity information can be obtained from tracer experiments, but we often lack information on the influence of soil properties on tracer mobility. This study features a combined experimental and modelling approach geared towards the evaluation of different structures in the multiple interacting pathways (MIPs) model and validates the representation of velocities with laboratory tracer experiments using an undisturbed soil column. Results indicate that the soil microstructure was modified during the experiment. Soil water velocities were represented using MIPs, testing how the (a) shape of the velocity distribution, (b) transition probability matrices (TPMs), (c) presence of immobile storage, and (d) nonstationary field capacity influence the model's performance. In MIPs, the TPM controls exhanges of water between pathways. In our experiment, MIPs were able to provide a good representation of the pattern of outflow. The results show that the connectedness of the faster pathways is important for controlling the percolation of water and tracer through the soil. The best model performance was obtained with the inclusion of immobile storage, but simulations were poor under the assumption of stationary parameters. The entire experiment was adequately simulated once a time-variable field capacity parameter was introduced, supporting the need for including the effects of soil microstructure changes observed during the experiment. © 2019 The Authors Hydrological Processes Published by John Wiley & Sons Ltd
AB - Models must effectively represent velocities and celerities if they are to address the old water paradox. Celerity information is recorded indirectly in hydrograph observations, whereas velocity information is more difficult to measure and simulate effectively, requiring additional assumptions and parameters. Velocity information can be obtained from tracer experiments, but we often lack information on the influence of soil properties on tracer mobility. This study features a combined experimental and modelling approach geared towards the evaluation of different structures in the multiple interacting pathways (MIPs) model and validates the representation of velocities with laboratory tracer experiments using an undisturbed soil column. Results indicate that the soil microstructure was modified during the experiment. Soil water velocities were represented using MIPs, testing how the (a) shape of the velocity distribution, (b) transition probability matrices (TPMs), (c) presence of immobile storage, and (d) nonstationary field capacity influence the model's performance. In MIPs, the TPM controls exhanges of water between pathways. In our experiment, MIPs were able to provide a good representation of the pattern of outflow. The results show that the connectedness of the faster pathways is important for controlling the percolation of water and tracer through the soil. The best model performance was obtained with the inclusion of immobile storage, but simulations were poor under the assumption of stationary parameters. The entire experiment was adequately simulated once a time-variable field capacity parameter was introduced, supporting the need for including the effects of soil microstructure changes observed during the experiment. © 2019 The Authors Hydrological Processes Published by John Wiley & Sons Ltd
KW - celerity
KW - soil properties
KW - tracer mobility
KW - velocity
KW - Microstructure
KW - Soil moisture
KW - Soil testing
KW - Solvents
KW - Velocity
KW - Different structure
KW - Laboratory experiments
KW - Soil microstructures
KW - Soil property
KW - Tracer experiment
KW - Transition probability matrix
KW - Velocity information
KW - Velocity distribution
U2 - 10.1002/hyp.13466
DO - 10.1002/hyp.13466
M3 - Journal article
JO - Hydrological Processes
JF - Hydrological Processes
SN - 0885-6087
ER -