2008 HYDRUS Package for MODFLOW
The one-dimensional unsaturated flow package HYDRUS (Seo et al., 2006; Twarakawi et al., 2008ab), accounting for fluxes through the vadose zone, was developed in 2008 for the three-dimensional modular finite-difference ground water model MODFLOW (Harbaugh et al., 2000). The HYDRUS package for MODFLOW consists of two sub-models that interact in space and time: (a) HYDRUS sub-model (vadose zone) and (b) MODFLOW sub-model (ground water). The HYDRUS package is based on the Hydrus-1D program (Šimůnek et al., 2005) that solves the one-dimensional Richards equation simulating water movement in the vadose zone. The HYDRUS package considers the main processes and factors affecting fluxes in the vadose zone, such as precipitation, infiltration, evaporation, redistribution, capillary rise, plant water uptake, water accumulation at the ground surface, surface runoff, and soil moisture storage. Being fully incorporated into the MODFLOW program, the HYDRUS package provides MODFLOW with recharge fluxes into groundwater, while MODFLOW provides HYDRUS with the position of the groundwater table that is used as the bottom boundary condition in the package. The performance of the HYDRUS package is analyzed by (Twarakawi et al., 2008) for various case studies that involve different spatial and temporal scales.
Downloads
Download the program and the template of the input file : Executable+Template of Input File.zip - 1.3 MB.
Download the example discussed in the manual (Seo et al., 2007): HYDRUS_Manual_Example.zip - 1.4 MB
Donwload examples evaluated by Twarakawi et al. (2008):
- Vauclin Recharge Study.zip (1.4 MB)
- Hypothetical 3D Example.zip (2.2 MB)
Source code and the manual of version 2.0 of the HYDRUS package for MODFLOW:
- Download the source code: Source Code.zip (0.6 MB)
- Download Instructions for input preparation: UpdatedInput_Hydrus.pdf (0.1 MB)
Test Example: Hypothetical Regional-Scale Ground Water Flow Problem
Download - Hypothetical 3D Example.zip (2.2 MB) This case study involved a hypothetical large-scale groundwater flow problem in a semi-arid/arid region. The geometry of the modeling domain is based on the test example described in Prudic et al. (2004) and Niswonger et al. (2006). The model domain was designed to represent an alluvial basin with loamy soils. Figure below shows the model domain and other key characteristics for this hypothetical regional scale groundwater flow problem.
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The flow domain was divided into uniform grids of 1524 by 1524 m size. Two cells were assigned a general head boundary condition in order to simulate head-dependent flux boundaries to allow flow in and out of the system. At the head-dependent flux boundary, water enters the model domain if the head in the cell is less than a certain user-defined reference head and leaves the model domain otherwise. The alluvium valley aquifer was assumed to have greater hydraulic conductivity than the upland areas.
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Figure below shows surface elevations, bedrock depth and initial water table depths in the study area. The geological settings were varied spatially in order to present a complex three-dimensional case.
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The modeling time was divided into 12 equal stress periods, each of which lasted 30.42 days. Except for the first stress period, the remaining stress periods were modeled in MODFLOW in the transient mode with 15 time steps for each stress period. The first stress period was modeled as steady-state. The meteorological conditions were assigned to represent a semi-arid climate where potential evaporation rates are substantially higher than precipitation rates. While different precipitation rates were assigned for each stress period, the spatial distribution of precipitation rates was considered to be the same for all stress periods. Figure below shows the zones used in the HYDRUS package for the hypothetical vadose zone-aquifer interaction problem.
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Figure below shows the groundwater flux zones estimated for different stress periods. Note that depending on various hydrological and topological conditions, the HYDRUS package predicts both positive (downward) recharge and negative (upward, capillary rise) discharge fluxes. Water table fluxes at any cell are directly influenced by surface infiltration, evaporation, and transpiration, as well as pumping rates in and around a particular cell. During the initial stress periods, the HYDRUS package predicted considerable upward fluxes; especially in cells where the precipitation rates were lower Cells with deeper initial water tables were less affected by evaporation than those with shallow initial water tables. As the simulation time proceeded, the number of cells with upward fluxes decreased because of the infiltration front movement towards the water table.
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Figure below shows the final water table depths.
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Independent Evaluations
The HYDRUS package has been independently evaluated and compared against the UZF package by Ashok and Sophocleous (2008).
The purpose of this report was to test and evaluate a number of recent improvements and additions that had been made to the standard U.S. Geological Survey MODFLOW ground-water flow model since 2000. Thus, two new streamflow packages, SFR1 and SFR2 were compared against the original streamflow package STR. The new ground-water evapotranspiration package ETS1 was compared against the original EVT package. The unsaturated flow packages UZF1, HYDRUS, and MODFLOW-HYDRUS were also evaluated. Finally, the conduit flow package (CFP) was also tested and evaluated. Major advantages and disadvantages of some of these packages were pointed out.
Quotation from page 90: MODFLOW Hydrus package looks more realistic than the UZF package, and the MODFLOW Hydrus is recommended, rather than the UZF package, to simulate the unsaturated soil-water balance.
Ashok, K. C., and Marios Sophocleous, Recent MODFLOW developments for groundwater modeling, Kansas Geological Survey Open-file Report 2009-4, Kansas Geological Survey, pp. 145, 2008 (pdf).
References
Harbaugh, A. W., E. R. Banta, M. C. Hill, and M. G. McDonald, MODFLOW-2000, the U.S. Geological Survey modular ground-water model user guide to modularization concepts and the ground-water flow process. Denver, CO, Reston, VA: U.S. Geological Survey, 2000 (http://water.usgs.gov/nrp/gwsoftware/modflow2000/modflow2000.html).
Niswonger, R.G., D.E. Prudic, and R.S. Regan. 2006. Documentation of the Unsaturated-Zone Flow (UZF1) package for modeling unsaturated flow between the land surface and the water table with MODFLOW-2005 [Online]. Available by U.S. Geological Survey (http://pubs.usgs.gov/tm/2006/tm6a19/).
Prudic, D. E., L. F. Konikow, and E. R. Bant, A new stream- flow routing (SFR1) package to simulate stream-aquifer interaction with MODFLOW-2000, U.S. Geological Survey Open-File Report 2004-1042, 95 p., 2004 (http://pubs.usgs.gov/of/2004/1042/).
Seo, H. S., J. Šimůnek, and E. P. Poeter, Documentation of the HYDRUS Package for MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model, GWMI 2007-01, Int. Ground Water Modeling Center, Colorado School of Mines, Golden, CO, 96 p., 2007. (PDF).
Šimůnek, J., M. Th. van Genuchten, and M. Šejna, The Hydrus-1D software package for simulating the one-dimensional movement of water, heat, and multiple solutes in variably-saturated media, Version 3.0, HYDRUS Software Series 1, Department of Environmental Sciences, University of California Riverside, Riverside, CA, 270 pp., 2005 (PDF 2.7MB)
Twarakavi, N. K. C., J. Šimůnek, and H. S. Seo, Evaluating interactions between groundwater and vadose zone using HYDRUS-based flow package for MODFLOW, Vadose Zone Journal, doi:10.2136/VZJ2007.0082, Special Issue “Vadose Zone Modeling”, 7(2), 757-768, 2008. Download PDF (2.2MB): Twarakavi et al., VZJ - 2008, Hydrus package for Modflow, Special Issue Vadose Zone Modeling.pdf
Twarakavi, N. K. C., J. Šimůnek, and S. Seo, A HYDRUS based approach for coupled modeling of vadose zone and ground water flow at different scales, In: J. Šimůnek and R. Kodešová (eds.), Proc. of The Second HYDRUS Workshop, March 28, 2008, Dept. of Soil Science and Geology, Czech University of Life Sciences, Prague, Czech Republic, pp. 47-53, 2008b. (Proceedings - Prague's HYDRUS Worskshop.pdf - 3.3MB)
Leterme, B., M. Gedeon, and D. Jacques, Groundwater recharge modeling in the Nete catchment (Belgium) with HYDRUS-1D – MODFLOW package, In: Šimůnek, J., M. Th. van Genuchten, and R. Kodešová (eds.), Proc. of the 4th International Conference "HYDRUS Software Applications to Subsurface Flow and Contaminant Transport Problems", Invited paper, March 21-22, 2013, Dept. of Soil Science and Geology, Czech University of Life Sciences, Prague, Czech Republic, ISBN: 978-80-213-2380-3, pp. 235-244, 2013. (pdf)
Leterme, B., M. Gedeon, E. Laloy, and B. Rogiers, Unsaturated flow modeling with HYDRUS and UZF: Calibration and intercomparison, In: MODFLOW and More 2015, Golden, CO, 2015, Integrated GroundWater Modeling Center, May 31- June 3, 2015. (pdf)
Szymkiewicz, A., A. Gumuła-Kawęcka, J. Šimůnek, B. Leterme, S. Beegum, B. Jaworska-Szulc, M. Pruszkowska-Caceres, W. Gorczewska-Langner, R. Angulo-Jaramillo, and D. Jacques, Simulation of freshwater lens recharge and salt/freshwater interfaces using the Hydrus and SWI2 packages for Modflow, Journal of Hydrology and Hydromechanics, 66(2), 246-256, doi: 10.2478/johh-2018-0005, 2018.(pdf)