Parameterization of two‐dimensional approaches in HYDRUS‐2D: Part 1. Simulating water flow dynamics at the field scale

Self Cite

In this study, a tracer field experiment was conducted to study the temporal dynamics of bromide movement in a loamy tile-drained agricultural landscape. Moreover, tritium leaching experiments were performed on undisturbed soil columns from the same field. The HYDRUS-2D software package was used to model water and solute transport. Three water flow models developed in Part 1-a single-porosity approach with modified soil hydraulic functions (SP), a dual-porosity approach (DP), and a dual-permeability approach (DUP)-were used as a foundation for building solute transport models, of which the initial parameterization was based on a suggested hydrogeological tool from previous studies. The selected solute transport models were an SP, an SP with immobile water, a DP, a DUP, and a DUP with immobile water. The model predictions were compared against measurements of bromide concentrations in soil-water. The DP captured the degree of the initial peaks and predicted well the shape of the observed concentrations. However, DP presented low capability to match the timing of bromide concentration peaks. In contrast, the DUP with immobile water illustrated better predictive ability by introducing an additional pore region into the matrix domain. Validation of field-scale solute transport models was implemented using the data from the following leaching experiments. The already suggested parameterization concept was further evaluated for its capability to provide a sufficient initial representation of the internal pathways. The output from such hydrogeological studies shows that macropores and their interconnection with tile drains are key to understanding the water flow and solute transport processes in loamy structured soils.

Section: Core Ideasmentioning

confidence: 97%

Section: Core Ideasmentioning

confidence: 99%

Section: In Situ Measurements and Soil Samplingmentioning

confidence: 99%

Section: Laboratory Measurements and Experimentsmentioning

confidence: 99%

Section: Laboratory Measurements and Experimentsmentioning

confidence: 99%

See 3 more Smart Citations

Parameterization of two‐dimensional approaches in HYDRUS‐2D: Part 2. Solute transport at the field and column scale

Varvaris

Pittaki‐Chrysodonta

Børgesen

et al. 2021

Self Cite

Parameterization of two‐dimensional approaches in HYDRUS‐2D: Part 1. Simulating water flow dynamics at the field scale

Varvaris

Pittaki‐Chrysodonta

Børgesen

et al. 2021

Self Cite

Parameterization of theeffective properties as input in hydrogeological models for simulating water flow is a time consuming and costly process, and it is characterized by high uncertainty because of the spatial variability of soil properties. Integrating visible−near-infrared spectroscopy (vis−NIRS) models and a developed pedotransfer function, a hydrogeological tool was suggested by Varvaris et al. in 2019 for estimating the hydraulic properties used in an equilibrium approach. In the current study, the proposed concept was further expanded for assisting on a rapid and inexpensive parameterization of effective parameters in nonequilibrium models. In our approach, the soil-water retention curves for the wet and hyper-dry ends were predicted using existing vis−NIRS calibration models for obtaining the parameters for the Campbell retention model and the Campbell and Shiozawa model, respectively.The HYDRUS-2D software package was used to simulate tile drainage discharge in a loamy structured field using as initial input hydraulic parameters the output from the suggested concept. The estimated parameters were validated based on measured hydraulic properties in the laboratory. Two-dimensional models incorporating nonequilibrium flow were used to evaluate the ability of each approach to predict the tile drainage discharge: a single-porosity with modified van Genuchten function, a dual-porosity model, and a dual-permeability model. All approaches gave a fairly good fit to the hydrograph features for both calibration and validation datasets with dual-porosity to present the highest predictive ability. Finally, the suggested initial parameterization concept proved its potential to be used as an alternative for covering the absence of measured data of soil hydraulic properties.

3D surface–subsurface modeling of a bromide tracer test in a macroporous tile‐drained field: Improvements and limitations

Boico

Therrien

Fleckenstein

et al. 2023

Self Cite

The assessment and forecasting of nutrient loss by tile drains in agricultural areas often rely on physically based models that have adequate representations of macropores and tile drains. Macroporosity has been adequately represented in hydrological models using a dual continuum approach. However, its implementation in hydrological and solute transport models is limited to plot-scale or to one-and two-dimensional models due to the large number of parameters that are rarely available and the long computational times. The purpose of this study is to simulate a tracer test using a 3D coupled surface-subsurface model to improve the representation of the tracer concentration at the drainage discharge. A three-dimensional HydroGeoSphere model was developed and calibrated to simulate tile drainage discharge, Br mass discharge, and hydraulic heads from a Br tracer test in a densely tile-drained field. The conductivity of the drain was one of the most important parameters for drain discharge and solute transport simulations. The model accurately simulated drainage discharge and Br transport to tile drains. However, most of the Br peaks and the late-time Br mass in the drain outflow were underestimated. Our simulation results indicate that explicitly representing tile drains with seepage nodes allows for a physically based, yet computationally efficient representation of Br transport behavior surrounding tile drains at field scale. However, we cannot confirm that the single-porosity model with immobile zone is suitable for simulating the Br peaks at the drain outlet and the late-time Br mass. Improvements to the model include the implementation of heterogeneous soil layers and the inclusion of more measured data to reduce uncertainty during calibration.