scholarly journals Numerical Modeling of Water Flow in Expansive Soils with Simplified Description of Soil Deformation

2018 ◽  
Vol 65 (4) ◽  
pp. 301-313
Author(s):  
Sławomir Michalski ◽  
Adam Szymkiewicz
Keyword(s):  
Water Flow ◽  
Unsaturated Flow ◽  
Expansive Soils ◽  
Vertical Direction ◽  
Time Discretization ◽  
Soil Mass ◽  
Flow Equation ◽  
Anthropogenic Factors ◽  
Equilibrium Equations ◽  
Stress Equilibrium

AbstractIn this paper we describe a numerical model of transient water flow in unsaturated expansive soils and the resulting soil volume change. The unsaturated flow equation is solved in a 2D domain using a finite-volume method and an explicit time discretization scheme. Strains in the soil mass are calculated by two simplified approaches, assuming that the strain state is either 1D (in the vertical direction only) or 2D with equal strains in horizontal and vertical directions. The model is applied to two cases described in the literature, in which the strains were computed from the solution of the stress equilibrium equation. It is shown that the simplified methods give results which are reasonably close to the more complex approach based on the equilibrium equations. The proposed model can be used to predict time-varying soil shrinkage and swelling caused by natural and anthropogenic factors.

Behavior and Distribution of Nonylphenol Ethoxylates and their Metabolites in Sediments of Nansi Lake, China

2011 ◽  
Vol 356-360 ◽  
pp. 1733-1738
Author(s):  
Fang He ◽  
Aya Obara ◽  
Shi Long Wang ◽  
Li Guo Wang
Keyword(s):  
Water Flow ◽  
Flow Direction ◽  
Sediment Cores ◽  
Sewage Treatment ◽  
Vertical Direction ◽  
Total Content ◽  
Horizontal Distribution ◽  
Nansi Lake ◽  
Increasing Trend ◽  
Vertical And Horizontal Distribution

The vertical and horizontal distribution of NPEOn and their metabolites of NP and NPEnC in the Upper Nansi Lake, North China were investigated using LC-MS and LC-MS/MS methods, sampling at three sites (St.1, St.2 and St.3) along the water flow direction. The total content of NPEOn (n=1–15) bound onto the sediment of this lake changed in the range of 60.7–631.5 μg/kg-dry with the horizontal flow direction and the vertical direction of the sediment cores with sediment thickness up to 35 cm. Compared to the presence levels of all detected NPEOn species, the content of NP was much higher, falling in 26.5–1,998.4 μg/kg-dry. A general increasing trend of the NP content along the water flow direction of this lake was revealed. NPEnC showed a roughly increasing trend from the upstream to the downstream, with the total concentrations being obviously lower than NPEOn and NP and falling in 2.13–23.1 μg/kg-dry. The short chain NPEOn dominant in NPEO mixtures in these sedimentary cores indicated that this lake received some effluents from STPs, and the sewage treatment ratio is relatively low in this area. Furthermore, the computed magnitudes of NPEO 1-2/NPEO1-15, NP/NPEO 1-15 and NPEC 1-10/NPEO 1-15 suggested that the non-oxidative hydrolytic transformation seemed to be a major process occurring within the sediment phase of Nansi Lake, while the oxidative hydrolytic transformation pathway was probably less involved.

scholarly journals An ice-shelf model test based on the Ross Ice Shelf, Antarctica

1996 ◽  
Vol 23 ◽  
pp. 46-51 ◽  
Author(s):  
D. R. MacAyeal ◽  
V. Rommelaere ◽  
P. Huybrechts ◽  
C. L. Hulbe ◽  
J. Determann ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Large Scale ◽  
Finite Difference Methods ◽  
Equilibrium Equations ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Stress Equilibrium ◽  
Flow Features ◽  
Large Scale Flow

A standard numerical experiment featuring the Ross Ice Shelf, Antarctica, is presented as a test package for the development and intercomparison of ice-shelf models. The emphasis of this package is solution of stress-equilibrium equations for an ice-shelf velocity consistent with present observations. As a demonstration, we compare five independently developed ice-shelf models based on finite-difference and finite-element methods. Our results suggest that there is little difference between finite-element and finite-difference methods in capturing the basic, large-scale flow features of the ice shelf. We additionally show that the fit between model and observed velocity depends strongly on the ice-shelf temperature field, for which there is presently little observational control. The main differences between model results are due to the equations being solved, the boundary conditions at the ice from and the discretization method (finite element vs finite difference).

scholarly journals Large-scale rheology of the Ross Ice Shelf, Antarctica, computed by a control method

1997 ◽  
Vol 24 ◽  
pp. 43-48 ◽  
Author(s):  
Vincent Rommelaere ◽  
Douglas R. MacAyeal
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Equilibrium Equations ◽  
Ice Shelf ◽  
The West ◽  
Ross Ice Shelf ◽  
Stress Equilibrium ◽  
West Antarctic ◽  
Flow Law ◽  
Basal Melting

Measurements made during the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS, 1973–78) are used to determine the large-scale rheological conditions of the Ross Ice Shelf, Antarctica. Our method includes a numerical ice-shelf model based on the stress-equilibrium equations and control theory. We additionally perform a few tests on simplified geometries to investigate the precision of our method. Our results consist of a map of the depth-averaged viscosity of the central part of the Ross Ice Shelf to within an uncertainty of 20%. We find that the viscosity variations are consistent with Glen’s flow law. Application of a more realistic flow law in our study provides little enhancement of ice-shelf model accuracy until uncertainties associated with basal melting conditions and with temperature profiles at inflow boundaries are addressed. Finally, our results suggest a strong viscosity anomaly in the west-central part of the ice shelf, which is interpreted to be associated with changes in the dynamics of Ice Stream A or B at least 1000 years ago. This feature conforms to the prevailing notion that the West Antarctic ice streams are unsteady.

Large-scale rheology of the Ross Ice Shelf, Antarctica, computed by a control method

1997 ◽  
Vol 24 ◽  
pp. 43-48 ◽  
Author(s):  
Vincent Rommelaere ◽  
Douglas R. MacAyeal
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Equilibrium Equations ◽  
Ice Shelf ◽  
The West ◽  
Ross Ice Shelf ◽  
Stress Equilibrium ◽  
West Antarctic ◽  
Flow Law ◽  
Basal Melting

Measurements made during the Ross Ice Shelf Geophysical and Glaciological Survey (RIGGS, 1973–78) are used to determine the large-scale rheological conditions of the Ross Ice Shelf, Antarctica. Our method includes a numerical ice-shelf model based on the stress-equilibrium equations and control theory. We additionally perform a few tests on simplified geometries to investigate the precision of our method. Our results consist of a map of the depth-averaged viscosity of the central part of the Ross Ice Shelf to within an uncertainty of 20%. We find that the viscosity variations are consistent with Glen’s flow law. Application of a more realistic flow law in our study provides little enhancement of ice-shelf model accuracy until uncertainties associated with basal melting conditions and with temperature profiles at inflow boundaries are addressed. Finally, our results suggest a strong viscosity anomaly in the west-central part of the ice shelf, which is interpreted to be associated with changes in the dynamics of Ice Stream A or B at least 1000 years ago. This feature conforms to the prevailing notion that the West Antarctic ice streams are unsteady.

scholarly journals A free boundary problem describing the saturated-unsaturated flow in a porous medium. Part II. Existence of the free boundary in the 3D case

2005 ◽  
Vol 2005 (8) ◽  
pp. 813-854 ◽  
Author(s):  
Gabriela Marinoschi
Keyword(s):  
Porous Medium ◽  
Free Boundary ◽  
Boundary Problem ◽  
Water Flow ◽  
Free Boundary Problem ◽  
Unsaturated Flow ◽  
A Free Boundary Problem

We present an extension of the results given in the first part of this paper (2004) referring to the existence in the3D case of a free boundary between the saturated and unsaturated domains that may be evidenced during the water flow into a porous medium.

scholarly journals Precipitation Sensitivity to the Uncertainty of Terrestrial Water Flow in WRF-Hydro: An Ensemble Analysis for Central Europe

2018 ◽  
Vol 19 (6) ◽  
pp. 1007-1025 ◽  
Author(s):  
Joël Arnault ◽  
Thomas Rummler ◽  
Florian Baur ◽  
Sebastian Lerch ◽  
Sven Wagner ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Variability ◽  
Central Europe ◽  
Water Flow ◽  
Daily Precipitation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Vertical Direction ◽  
Surface Flux ◽  
Terrestrial Water

Abstract Precipitation is affected by soil moisture spatial variability. However, this variability is not well represented in atmospheric models that do not consider soil moisture transport as a three-dimensional process. This study investigates the sensitivity of precipitation to the uncertainty in the representation of terrestrial water flow. The tools used for this investigation are the Weather Research and Forecasting (WRF) Model and its hydrologically enhanced version, WRF-Hydro, applied over central Europe during April–October 2008. The model grid is convection permitting, with a horizontal spacing of 2.8 km. The WRF-Hydro subgrid employs a 280-m resolution to resolve lateral terrestrial water flow. A WRF/WRF-Hydro ensemble is constructed by modifying the parameter controlling the partitioning between surface runoff and infiltration and by varying the planetary boundary layer (PBL) scheme. This ensemble represents terrestrial water flow uncertainty originating from the consideration of resolved lateral flow, terrestrial water flow uncertainty in the vertical direction, and turbulence parameterization uncertainty. The uncertainty of terrestrial water flow noticeably increases the normalized ensemble spread of daily precipitation where topography is moderate, surface flux spatial variability is high, and the weather regime is dominated by local processes. The adjusted continuous ranked probability score shows that the PBL uncertainty improves the skill of an ensemble subset in reproducing daily precipitation from the E-OBS observational product by 16%–20%. In comparison to WRF, WRF-Hydro improves this skill by 0.4%–0.7%. The reproduction of observed daily discharge with Nash–Sutcliffe model efficiency coefficients generally above 0.3 demonstrates the potential of WRF-Hydro in hydrological science.

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