scholarly journals Assessing the perturbations of the hydrogeological regime in sloping fens due to roads

2020 ◽  
Vol 24 (1) ◽  
pp. 213-226
Author(s):  
Fabien Cochand ◽  
Daniel Käser ◽  
Philippe Grosvernier ◽  
Daniel Hunkeler ◽  
Philip Brunner
Keyword(s):  
Numerical Models ◽  
Subsurface Flow ◽  
Flow Dynamics ◽  
Qualitative Assessment ◽  
Soil Conditions ◽  
Systematic Analysis ◽  
The Road ◽  
Wide Range ◽  
The Impact ◽  
Surface And Subsurface Flow

Abstract. Roads in sloping fens constitute a hydraulic barrier for surface and subsurface flow. This can lead to the drying out of downslope areas of the sloping fen as well as gully erosion. Different types of road construction have been proposed to limit the negative implications of roads on flow dynamics. However, so far, no systematic analysis of their effectiveness has been carried out. This study presents an assessment of the hydrogeological impact of three types of road structures in semi-alpine, sloping fens in Switzerland. Our analysis is based on a combination of field measurements and fully integrated, physically based modeling. In the field approach, the influence of roads was examined using tracer tests in which the area upslope of the road was sprinkled with a saline solution. The spatial distribution of electrical conductivity downslope provided a qualitative assessment of the flow paths and, thus, the implications of the road structures on subsurface flow. A quantitative albeit not site-specific assessment was carried out using fully coupled numerical models jointly simulating surface and subsurface flow processes. The different road types were implemented and their influence on flow dynamics was assessed for a wide range of slopes and different hydraulic conductivities of the soil. The models are based on homogenous soil conditions, allowing for a relative ranking of the impact of the road types. For all cases analyzed in the field and simulated using the numerical models, roads designed with an L drain (i.e., collecting water upslope and releasing it in a concentrated manner downslope) constitute the largest perturbations in terms of flow dynamics. The other road structures investigated were found to have less impact. The developed methodologies and results can be used for the planning of future road projects in sloping fens.

scholarly journals Assessing the perturbations of the hydrogeological regime in sloping fens through roads

2018 ◽  
Author(s):  
Fabien Cochand ◽  
Daniel Käser ◽  
Philippe Grosvernier ◽  
Daniel Hunkeler ◽  
Philip Brunner
Keyword(s):  
Numerical Models ◽  
Subsurface Flow ◽  
Tracer Tests ◽  
Field Measurements ◽  
Flow Dynamics ◽  
Qualitative Assessment ◽  
Systematic Analysis ◽  
The Road ◽  
Wide Range ◽  
Surface And Subsurface Flow

Abstract. Roads in sloping fens constitute a hydraulic barrier for surface and subsurface flow. This can lead to a drying out of downslope areas of the sloping fen as well as gully erosion. Different types of road construction have been proposed to limit the negative implications of the roads on flow dynamics. However, so far no systematic analysis of their effectiveness has been carried out. This study presents an assessment of the hydrogeological impact of three types of road structures in semi-alpine, sloping fens in Switzerland. Our analysis is based on a combination of field measurements and fully integrated, physically based modelling. In the field approach, the influence of the road was examined through tracer tests where the upslope of the road was sprinkled with a saline solution. The spatial distribution of electrical conductivity downslope provided a qualitative assessment of the flow paths and thus the implications of the road structures on subsurface flow. A quantitative albeit not site-specific assessment was carried out using numerical models simulating surface and subsurface flow in a fully coupled way. The different road types were implemented in the model and flow dynamics were simulated for a wide range of slopes and hydrogeological conditions such as different hydraulic conductivity of the soil. The results of the field and modelling analysis are coherent. Roads designed with an L-drain collecting water upslope and releasing it in a concentrated manner downslope constitute the largest perturbations. The other investigated road structures were found to have less impact. The developed methodologies and results are useful for the planning of future road projects.

scholarly journals Evaluation of the Impact of Spatial and Environmental Accident Factors on Severity Patterns of Road Segments

2020 ◽  
Author(s):  
Maen Qaseem Ghadi ◽  
Árpád Török
Keyword(s):  
Spatial Clustering ◽  
Decision Rules ◽  
Black Spot ◽  
Risk Level ◽  
Accident Risk ◽  
Severity Level ◽  
The Road ◽  
Wide Range ◽  
The Impact ◽  
Road Segments

Several studies have examined a wide range of accident risk factors affecting road safety. The purpose of this study is to examine the main traffic accident factors that affect the severity of road segments. The practical objective of the article is to assist specialists in identifying risk patterns both from a spatial and casualty point of view. To achieve the desired goals, accidents of a road network have been analyzed through three major steps; segmentation, black spot identification, and decision analysis. A new spatial clustering methodology has been used to divide accidents into smaller groups (or clusters) based on their spatial aggregations. The spatial characteristics are argued to be an important factor, in revealing the heterogeneity between accident data. Then, the empirical Bayesian has been applied to rank the resulted segments by severity level. During this step, the technique of decision rules has been applied to identify the main contributors to accidents in certain segments. The result shows that there is a significant relationship between the accident severity level and the traffic and geometrical characteristics (i.e. speed limits, average daily traffic, path shape) of road segments. The results also revealed that the closer the road to secure and non-hazardous road environmental conditions, the lower the risk level of the road segment.

scholarly journals Weak Land–Atmosphere Coupling Strength in HadAM3: The Role of Soil Moisture Variability

2005 ◽  
Vol 6 (5) ◽  
pp. 670-680 ◽  
Author(s):  
David M. Lawrence ◽  
Julia M. Slingo
Keyword(s):  
Boundary Layer ◽  
Soil Moisture ◽  
Coupling Strength ◽  
General Circulation ◽  
General Circulation Models ◽  
Soil Conditions ◽  
Wide Range ◽  
The Impact ◽  
Soil Moisture Variability ◽  
Moisture Variability

Abstract A recent model intercomparison, the Global Land–Atmosphere Coupling Experiment (GLACE), showed that there is a wide range of land–atmosphere coupling strengths, or the degree that soil moisture affects the generation of precipitation, amongst current atmospheric general circulation models (AGCMs). Coupling strength in the Hadley Centre atmosphere model (HadAM3) is among the weakest of all AGCMs considered in GLACE. Reasons for the weak HadAM3 coupling strength are sought here. In particular, the impact of pervasive saturated soil conditions and low soil moisture variability on coupling strength is assessed. It is found that when the soil model is modified to reduce the occurrence of soil moisture saturation and to encourage soil moisture variability, the soil moisture–precipitation feedback remains weak, even though the relationship between soil moisture and evaporation is strengthened. Composites of the diurnal cycle, constructed relative to soil moisture, indicate that the model can simulate key differences in boundary layer development over wet versus dry soils. In particular, the influence of wet or dry soil on the diurnal cycles of Bowen ratio, boundary layer height, and total heat flux are largely consistent with the observed influence of soil moisture on these properties. However, despite what appears to be successful simulation of these key aspects of the indirect soil moisture–precipitation feedback, the model does not capture observed differences for wet and dry soils in the daily accumulation of boundary layer moist static energy, a crucial feature of the feedback mechanism.

SOIL CONDITIONS OF FOREST VEGETATION GROWTH OF NORTHERN VOLGA

10.12737/3822 ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. 112-116
Author(s):  
Жубрин ◽  
Denis Zhubrin ◽  
Сабиров ◽  
Ayrat Sabirov
Keyword(s):  
Forest Soils ◽  
Forest Ecosystems ◽  
Biological Diversity ◽  
Basic Research ◽  
Economic Assessment ◽  
Forest Vegetation ◽  
Soil Conditions ◽  
Vegetation Growth ◽  
Wide Range ◽  
The Impact

Conducting soil studies are relevant in determining the subordination of forest types and biodiversity of vegetation to soil taxa, in determining the dependence of basic forest stand productivity from soil conditions, in creating a land registry and economic assessment of forest land, in studying the soil evolution of forest plantations under the impact of anthropogenic influences. Soil is the most important environmental factor in shaping the productivity and biodiversity of forest phytocenosis. The study of forest soils is also important in terms of basic research of their genesis, evolution. The article presents the results of research of soil conditions of vegetation growth of forest ecosystems of northern regions of Volga of the Republic of Tatarstan. The main types of forest soils are characterized in the paper. The studied forest formations grow on various soils on genesis and forest vegetation properties: sod-podzol, gray forest, brown forest, brown forest sandy, alluvial meadow, rendziny soil. The granulometric structure of soils varies from sandy to the clay. The well structured soils are formed on loamy layers under forest phytocenosis canopy. Pine and spruce ecosystems have a medi-decomposed litter of moder and multi-moder types; linden, oak, birch and aspen biogeocoenoses have strong-decomposed litter of multi type, that characterizes the intense biological cycle of substances in forest ecosystems. The wide range of place conditions of territories causes the biological diversity of forest vegetation at the level of species and ecosystems.

scholarly journals Experimental and FE Study on Impact Strength of Toughened Glass–Retrospective Approach

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7658
Author(s):  
Marcin Kozłowski ◽  
Kinga Zemła ◽  
Magda Kosmal ◽  
Ołeksij Kopyłow
Keyword(s):  
Numerical Models ◽  
Peak Stress ◽  
Impact Loads ◽  
Toughened Glass ◽  
Load Duration ◽  
Wide Range ◽  
Modelling Methodology ◽  
Glass Panels ◽  
Set Up ◽  
The Impact

Due to the high cost of experiments commonly performed to verify the resistance of glass elements to impact loads, numerical models are used as an alternative to physical testing. In these, accurate material parameters are crucial for a realistic prediction of the behaviour of glass panels subjected to impact loads. This applies in particular to the glass’s strength, which is strictly dependent on the strain rate. The article reports the results of an extensive experimental campaign, in which 185 simply supported toughened glass samples were subjected to hard-body impacts. The study covers a wide range of glass thicknesses (from 5 to 15 mm), and it aims to determine a critical drop height causing fracture of the glass. Moreover, a 3D numerical model of the experimental set-up was developed to reproduce the experiments numerically and retrospectively to determine the peak stress in glass that developed during the impact. Based on the results of numerical simulations, a load duration factor of 1.40 for toughened glass for impact loads is proposed. In addition, the paper includes a case study to demonstrate the use of the modelling methodology and results of the work on a practical example of an internal glass partition wall.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road toward a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, and the adhesion method on the bending efficiency and the bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

scholarly journals Emergence and establishment of native and non-native species in soils of remnant and converted highland grasslands – southern Brazil

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Helena de Lima Müller ◽  
Rodrigo Ramos Lopes ◽  
Julia-Maria Hermann
Keyword(s):  
Soil Type ◽  
Native Species ◽  
Seedling Emergence ◽  
Soil Conditions ◽  
Holcus Lanatus ◽  
Native Grasslands ◽  
Exotic Tree ◽  
Wide Range ◽  
Tussock Grass ◽  
The Impact

Abstract Native grasslands in the Campos de Cima da Serra, Brazil, are being converted at speed for exotic tree plantations and cropland. The impact of modified and novel soil conditions on the establishment of native grassland species is unknown; establishment of non-native species, deliberately or accidentally introduced, could be favoured. In a common garden composed of fully randomized replicate samples of soils collected from remnant grassland, former cropland and pine plantations, we tested emergence and establishment of five cold-season species: Native low-tussock grass Piptochaetium montevidense (Spreng.) Parodi; native legume Trifolium riograndense Burkart; naturalized low-tussock grass Vulpia bromoides (L.) Gray; low-tussock grass Holcus lanatus L., cultivated and naturalized in Brazil; and a cultivar of non-native Trifolium repens. Other than expected, soil type and species*soil type interactions had no significant effect on seedling emergence after 132 days in the field. Species effect on seedling emergence, however, was highly significant. Vulpia bromoides emergence was significantly highest in all soil types. Holcus lanatus and Trifolium riograndense both achieved second highest emergence rates and did not differ significantly from each other. Lowest overall emergence rates were found in the non-native clover cultivar. Lab germination tests failed for Piptochaetium, although it showed reasonable emergence in the field. Good performance of the native clover is encouraging for future grassland restoration, but the value of highly germinable Vulpia as a forage remains to be tested. Holcus tolerates a wide range of soil conditions and its life history traits may promote naturalization, or even invasiveness. Native grasslands of the region should be monitored for this species. Studies like these, but set up on a larger geographical scale and with a wider array of native species, will be essential in developing ecological restoration methods for southern Brazilian grasslands.

scholarly journals Structural Response and Stochastic Impact Modeling

2018 ◽  
Vol 183 ◽  
pp. 01050
Author(s):  
Renata Troian ◽  
Manel Dallali ◽  
Didier Lemosse ◽  
Leila Khalij
Keyword(s):  
Structural Model ◽  
Numerical Models ◽  
Structural Response ◽  
Point Of View ◽  
Structural Behavior ◽  
Beam Model ◽  
Wide Range ◽  
Extreme Sensitivity ◽  
The Impact ◽  
Bernoulli Beam Model

The problem of the vulnerability of structures facing explosions came to the front line of the scientific scene in the last decades. Uncertainty of the environmental conditions and material properties have to be taken into account. The corresponding numerical models are very complex and depend on numerous parameters. Consequently, such models are cursed with issues which limit their use for real applications. Most of the existing approaches are based on a deterministic point of view, and are not able to represent the extreme sensitivity of a model towards uncertain parameters. That is why the uncertainty analysis is needed. The proposed research is devoted to the analysis of a structural behavior under an uncertain impact loading. Elasto-plastic Bernoulli beam model is used as structural model for the case simplicity, while the different formulation for impact itself are studied to simulate the wide range of possible types of impact. Model sensitivity is studied first. The influence of input parameters on structural behavior, that are the impact force, duration and position, as well as beam material are then considered. The obtained insights can provide the guidelines for modeling the structure under the explosive loading taking into account the uncertainties.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Abstract Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road towards a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, as well as the adhesion method on the bending efficiency and bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally-induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy, to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

scholarly journals A high-resolution simulation of groundwater and surface water over most of the continental US with the integrated hydrologic model ParFlow v3

2015 ◽  
Vol 8 (3) ◽  
pp. 923-937 ◽  
Author(s):  
R. M. Maxwell ◽  
L. E. Condon ◽  
S. J. Kollet
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Numerical Models ◽  
Subsurface Flow ◽  
Hydrologic Model ◽  
Grand Challenge ◽  
Flow Equations ◽  
Continental Scale ◽  
Integrated Hydrologic Model ◽  
Surface And Subsurface Flow

Abstract. Interactions between surface and groundwater systems are well-established theoretically and observationally. While numerical models that solve both surface and subsurface flow equations in a single framework (matrix) are increasingly being applied, computational limitations have restricted their use to local and regional studies. Regional or watershed-scale simulations have been effective tools for understanding hydrologic processes; however, there are still many questions, such as the adaptation of water resources to anthropogenic stressors and climate variability, that can only be answered across large spatial extents at high resolution. In response to this grand challenge in hydrology, we present the results of a parallel, integrated hydrologic model simulating surface and subsurface flow at high spatial resolution (1 km) over much of continental North America (~ 6.3 M km2). These simulations provide integrated predictions of hydrologic states and fluxes, namely, water table depth and streamflow, at very large scale and high resolution. The physics-based modeling approach used here requires limited parameterizations and relies only on more fundamental inputs such as topography, hydrogeologic properties and climate forcing. Results are compared to observations and provide mechanistic insight into hydrologic process interaction. This study demonstrates both the feasibility of continental-scale integrated models and their utility for improving our understanding of large-scale hydrologic systems; the combination of high resolution and large spatial extent facilitates analysis of scaling relationships using model outputs.

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