Approaches to large scale unsaturated flow in heterogeneous, stratified, and fractured geologic media

The Danube-Tisza Interfluve is one of the largest areas covered by wind-blown sand in Hungary. Two major morphologic region types are the flat-bottomed valleys of the Danube and Tisza rivers and a central elevated ridge region, characterized by sand plains, dunes and deflationary depressions. The area is poor in surface waters, mainly artificial channels can be found. Previously many lakes were present, but most of them dried out due to water abstraction, climate change, forestation and canalization related water level reduction. Water management problems in the broader area have been known for decades, many plans have been made to address water scarcity, but none have materialized (Kov&#225;cs et al. 2017). These plans usually tried to solve water shortage with large scale engineering solutions, e.g. to pump water up from the Danube River Valley through surface channels to the ridge region (Nagy et al. 2016). This is very expensive, influences the ecological pattern, moreover water can easily infiltrate from the channels and would not reach the higher regions in the required amount (Silva Cisneros, 2019). The aim of the research was to examine the suitability of Managed Aquifer Recharge methods, then a local scale field research was carried out in order to find local scale solutions. Finally the results were checked by numerical simulation to contribute to the solution of water shortage of this ecologically important area. Firstly, a MAR surface infiltration suitability map was constructed, that shows areas with favorable hydraulic conductivity at the upper 10 m and low water levels, which means that there is a reservoir in the unsaturated zone to store infiltrated water. Based on suitability mapping, a local research area was selected which showed promising potential. Geophysical measurements (ERT &#8211; Electrical Resistivity Tomography, RMT &#8211; Radio-magnetotellurics) were performed, shallow wells were surveyed, and additional wells were drilled by hand driller. The results obtained during the field sampling contributed to the preliminary characterization of the area from a geological and hydrogeological point of view. In order to understand the effects of artificial channels and the possible water recharge methods a saturated-unsaturated flow model and different scenario models were built up in 2D. This local scale case study was a first step towards the further aim of this research, which is to understand the effects of man-made changes on groundwater flow systems in the broader area and suggest appropriate local scale MAR solutions accordingly.This research is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 810980.Kov&#225;cs, A. D., Hoyk, E., Farkas, J. Z. (2017). Homokh&#225;ts&#225;g&#8211;A semi-arid region facing with complex problems in the Carpathian Basin. European Countryside,&#160;9(1), 29-50. Nagy, I., Tomb&#225;cz, E., L&#225;szl&#243;, T., Magyar, E., M&#233;sz&#225;ros, Sz., Pusk&#225;s, E., Scheer, M. (2016). V&#237;zvisszatart&#225;si mintaprojektek a Homokh&#225;ts&#225;gon: &#8222;Nyugati &#233;s Keleti&#8221; mintater&#252;letek. Hidrol&#243;giai K&#246;zl&#246;ny, 96(4), 42-60. Silva Cisneros, C. (2019). Identification of suitable zones of Managed Aquifer Recharge (MAR) in Western area of Duna-Tisza Interfluve using Geographic Information System (GIS). MSc thesis. E&#246;tv&#246;s Lor&#225;nd University, 62.

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Modelling evaporation of paste tailings from the Bulyanhulu mine

Canadian Geotechnical Journal ◽

10.1139/t07-067 ◽

2007 ◽

Vol 44 (12) ◽

pp. 1417-1432 ◽

Cited By ~ 40

Author(s):

Paul Simms ◽

Murray Grabinsky ◽

Guosheng Zhan

Keyword(s):

Volume Change ◽

Large Scale ◽

Unsaturated Flow ◽

Field Trials ◽

Surface Deposition ◽

Permeability Function ◽

Sample Data ◽

Drying Rates ◽

Sulphate Salts ◽

Water Contents

Accurate predictions of drying rates are desirable to optimize surface deposition of thickened or paste tailings. A series of laboratory and field trials were implemented to study evaporation from tailings at the Bulyanhulu gold mine and were compared with numerical simulations using the unsaturated flow model SoilCover. The laboratory tests included two “large-scale” experiments on 10 cm thick layers of tailings 2 m by 1 m in plan, and a smaller column test on a 20 cm thick and 20 cm diameter sample. Data monitored during these tests included albedo, volume change, degree of cracking, matric suction, water content, and drying rate. Field data included gravimetric water contents and albedo values. The model could reasonably simulate the laboratory experiments when adjustments were made to account for self-weight consolidation and the effect of volume change on the relative permeability function. The model could simulate drying in the field for up to 3 weeks after deposition before the accumulation of gypsum and magnesium sulphate salts began to affect evaporation. Cracking and salt accumulation were observed both in the laboratory and in the field. A general model for simulating drying from paste tailings should incorporate the effects of cracking and salts.

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Stochastic modeling of large-scale transient unsaturated flow systems

Water Resources Research ◽

10.1029/wr023i001p00037 ◽

1987 ◽

Vol 23 (1) ◽

pp. 37-46 ◽

Cited By ~ 210

Author(s):

Aristotelis Mantoglou ◽

Lynn W. Gelhar

Keyword(s):

Stochastic Modeling ◽

Large Scale ◽

Unsaturated Flow ◽

Flow Systems

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Applied tracers for the observation of subsurface stormflow at the hillslope scale

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-2961-2009 ◽

2009 ◽

Vol 6 (2) ◽

pp. 2961-3006 ◽

Cited By ~ 2

Author(s):

J. Wienhöfer ◽

K. Germer ◽

F. Lindenmaier ◽

A. Färber ◽

E. Zehe

Keyword(s):

Large Scale ◽

Preferential Flow ◽

Unsaturated Flow ◽

Dispersion Model ◽

Breakthrough Curves ◽

Flow Paths ◽

Transient Flows ◽

Natural Rainfall ◽

Flow Features ◽

Hillslope Scale

Abstract. Rainfall-runoff response in temperate humid headwater catchments is mainly controlled by hydrological processes at the hillslope scale. Applied tracer experiments with fluorescent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow paths concertedly at a forested hillslope in the Austrian Alps. Dye staining experiments at the plot scale revealed that cracks and soil pipes function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rainfall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demonstrate qualitative and quantitative effects of preferential flow features on subsurface stormflow in a temperate humid headwater catchment. It turns out that, at the hillslope scale, the interactions of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigations of effective structures and parameters at the scale of interest.

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