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Sahila Beegum Jiří Šimůnek Adam Szymkiewicz K. P. Sudheer Indumathi M. Nambi 《Ground water》2019,57(3):392-408
The “HYDRUS package for MODFLOW” is an existing MODFLOW package that allows MODFLOW to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package is based on incorporating parts of the HYDRUS-1D model (to simulate unsaturated water flow in the vadose zone) into MODFLOW (to simulate saturated groundwater flow). The coupled model is effective in addressing spatially variable saturated-unsaturated hydrological processes at the regional scale. However, one of the major limitations of this coupled model is that it does not have the capability to simulate solute transport along with water flow and therefore, the model cannot be employed for evaluating groundwater contamination. In this work, a modified unsaturated flow and transport package (modified HYDRUS package for MODFLOW and MT3DMS) has been developed and linked to the three-dimensional (3D) groundwater flow model MODFLOW and the 3D groundwater solute transport model MT3DMS. The new package can simulate, in addition to water flow in the vadose zone, also solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption. Due to complex interactions at the groundwater table, certain modifications of the pressure head (compared to the original coupling) and solute concentration profiles were incorporated into the modified HYDRUS package. The performance of the newly developed model is evaluated using HYDRUS (2D/3D), and the results indicate that the new model is effective in simulating the movement of water and contaminants in the saturated-unsaturated flow domains. 相似文献
2.
Smolíková Jana Hrbáček Filip Blahůt Jan Klimeš Jan Vilímek Vít Loaiza Usuga Juan Carlos 《Natural Hazards》2021,106(3):2353-2379
Natural Hazards - Two significant rainfall episodes affected the eastern part of the Czech Republic in May 2010 causing dozens of landslides, including a potentially damaging debris flow on... 相似文献
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Simultaneous measurement of coupled water, heat, and solute transport in unsaturated porous media is made possible with the multi-functional heat pulse probe (MFHPP). The probe combines a heat pulse technique for estimating soil heat properties, water flux, and water content with a Wenner array measurement of bulk soil electrical conductivity (ECbulk). To evaluate the MFHPP, we conducted controlled steady-state flow experiments in a sand column for a wide range of water saturations, flow velocities, and solute concentrations. Flow and transport processes were monitored continuously using the MFHPP. Experimental data were analyzed by inverse modeling of simultaneous water, heat, and solute transport using an adapted HYDRUS-2D model. Various optimization scenarios yielded simultaneous estimation of thermal, solute, and hydraulic parameters and variables, including thermal conductivity, volumetric water content, water flux, and thermal and solute dispersivities. We conclude that the MFHPP holds great promise as an excellent instrument for the continuous monitoring and characterization of the vadose zone. 相似文献
4.
Summary The propagator matrix is expressed in terms of cross-products of spherical Bessel functions and their derivatives. A fast computational algorithm is suggested. The matrix form of the variational principle with the boundary term is derived.
u nu u u u, n¶rt; u¶rt; nu¶rt;u uu u u u nuo¶rt;. ¶rt; au u . ¶rt; u uau nuuna u .相似文献
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Analysis of infiltration processes into fractured and swelling soils as triggering factors of landslides 总被引：2，自引：0，他引：2
Rainfall infiltration can cause a dramatic decrease of suction in unsaturated soils and, consequently, of shear strength, triggering various instability phenomena, such as the slip of steep surface soil layers. Swelling of cracked soils and capillary barrier effects, induced by fine-grained soils overlying a more permeable material, can also affect water flow through this type of soil systems. In the past, few studies on infiltration and rainfall-induced landslides considered the simultaneous effects of surface cracks, swelling materials, and/or the capillary barrier phenomenon. To this purpose, this paper presents the results obtained by a dual-permeability model, which simulates water flow through a fractured swelling soil overlying a more permeable soil and focusing on the influence of these phenomena on triggering of landslides. Numerical results show that for high-intensity precipitations, flow through fractures quickly reaches significant depths and the capillary barrier is broken, while soil swelling leads to a uniform narrowing of cracks. On the other hand, for low-intensity precipitations, fracture flow and swelling are limited only to the first 30–50 cm of the topsoil, while cracks almost completely closed. Evaluations of the slope stability show that prolonged low-intensity rainfalls might be more dangerous than short high-intensity rains in triggering surface landslides. 相似文献
7.
The main objective of this study was to identify the main sources and processes that control SO4 2? groundwater concentrations in the Jinghuiqu irrigation district of China using isotope analysis. Lysimeter irrigation experiments and numerical modeling were used to assess the impact of long-term irrigation practices on sulfate transport, when different sources of irrigation water were used. SO4 2? concentrations in the groundwater of the entire irrigation area increased significantly from the years 1990 (a mean value was 4.8 mmol L?1) to 2009 (a mean value was 9.84 mmol L?1). The δ34S-SO4 2? values (ranging from +5.27 to +10.69 ‰) indicated that sulfates in groundwater were initially predominantly derived from dissolution of minerals. However, no soluble sulfate minerals (gypsum and/or mirabilite) were detected after 1990. To better understand this seeming anomaly, water content and SO4 2? data were collected before and after the field irrigation experiment and analyzed using the HYDRUS-1D and HP1 software packages. The experimental data were also used to assess sulfate leaching when different sources of irrigation water were used under current irrigation practices. The dissolved sulfate concentrations in the soil profile increased significantly when groundwater was used for infiltration compared to the use of surface water. Irrigation water sources had a great impact on the increase of sulfate concentrations in the shallow groundwater, especially when groundwater with elevated concentrations was used for irrigation. 相似文献
8.
Aleš Kapička Radka Kodešová Eduard Petrovský Zdeněk Hůlka Hana Grison Martin Kaška 《Studia Geophysica et Geodaetica》2011,55(4):683-696
Several studies have shown that magnetic measurements can be used in assessing soil contamination due to atmospheric deposition
of pollutants. Reliable spatial mapping of magnetic susceptibility of soils assumes high temporal stability of deposited particles,
accumulated in top-soil horizons. One of the main methodological concerns is whether the migration of deposited anthropogenic
ferrimagnetic particles may bias the measured values. Measurements carried out on high-porosity (sandy) soils, or on soils
with a very variable water regime may yield inconsistent values of top-soil magnetic susceptibility as the indicator of contamination.
This study focuses on the laboratory examination of migration of fly ashes from a coal-burning power plant in sands of different
porosity and under a simulated rain regime. Columns of sand of different grain sizes, placed in plastic cylinders, were contaminated
on the surface by the fly ash. The vertical migration of magnetic particles was monitored using measurements of magnetic susceptibility
with an SM400 Kappameter. Calibration measurements in the water environment showed an erroneous performance and resulted in
the technical improvement of the used susceptibility meter (Model 2009). Our results show that the vertical distribution of
flyash particles deposited on fine sand is very stable even after repeated rain simulation. The peak value of magnetic susceptibility
is located in a stable position a few millimeters under the surface. Hence, standard top-soil magnetic mapping is in such
a case reliable and fully representative. Contrary to that, in case of coarse sand, the peak value of magnetic susceptibility
migrates by more than 10 cm. The results will be further used for numerical modeling of contaminant transport in porous media. 相似文献
9.
Abstract Large-scale agricultural activities cause deterioration of groundwater resources throughout the world. This study focuses on the irrigated agricultural district of Jinghuiqu in Shaanxi, China. The objectives are to identify the main sources and processes that control nitrate transport, and to assess the impact of long-term irrigation practices on nitrate leaching. The hydrogeochemistry of major solute constituents and stable isotope ratios of NO3 ? in groundwater were used to identify historical sources of contamination and transformation processes occurring in the shallow groundwater of the Jinghuiqu irrigation district. The N-NO3 ? concentrations in groundwater ranged from 0.0 to more than 100 mg L?1 in April 1990, and from 0.47 to 42.0 mg L?1 in December 2009. Our measurements of N-NO3 ? show that the main reasons for this dramatic decline in N-NO3 ? concentrations from 1990 to 2009 are denitrification, which controls nitrogen types, together with the sharp decline of the groundwater table. The isotope ratios in collected samples showed that the source of nitrate was mainly manure, a result that corresponds with historical data showing that manure was the main nitrate source before the 1980s, and that fertilizers became dominant thereafter. A numerical model was then used to evaluate future impacts of current irrigation practices on groundwater sources. The HYDRUS-1D model was employed first to evaluate the water movement and the N-NO3 ? solute transport for a single irrigation pulse experiment carried out under field conditions, and then in evaluating the long-term impact of irrigation on N-NO3 ? leaching. Simulations showed that, after introducing irrigation, the downward drainage fluxes of N-NO3 ?, and the N-NO3 ? and N-tot concentrations increased at all depths within the 2-m soil profile. This indicates that N concentrations below 1-m depth and in the groundwater could become even more elevated with increased future irrigation. Editor D. Koutsoyiannis Citation Liu, X.-H., Sun, S.-J., Ji, P., and ?im?nek, J., 2013. Evaluation of historical nitrate sources in groundwater and impact of current irrigation practices on groundwater quality. Hydrological Sciences Journal, 58 (1), 1–15. 相似文献
10.
Jan Kocum Filip Oulehle Bohumír Janský František Bůzek Jakub Hruška Lukáš Vlček 《水文科学杂志》2013,58(14):2579-2589
ABSTRACTA geochemical approach using stable oxygen isotopes was used to understand streamflow generation processes in the highly peaty catchment of the Rokytka Brook in the headwaters of the Vltava River, Czech Republic. The contribution of water from peat bog areas to the total surface runoff was assessed using a hydrological time series, as well as geochemical, hydrochemical and isotope-hydrological approaches for unit hydrogram separation by means of anion deficiency. Using data from the hydrological year 2008, the role of an existing peat bog in the runoff formation dynamics of the Rokytka Brook catchment was determined, and the hydrological cycle was described and assessed using stable 18O/16O isotopes. The research findings strongly support the fact that peatland areas within the studied catchment do not significantly communicate hydraulically with surface streams, and their hydrological function in this region is insignificant.
Editor M. C. Acreman; Associate editor not assigned 相似文献