scholarly journals Movement of Soil Water and Solute through Coal Ash Layer Packed in Large-Scale Lysimeter

1992 ◽  
Vol 36 ◽  
pp. 397-402
Author(s):  
Toshifumi IGARASHI ◽  
Hisashi SHIMOGAKI
Keyword(s):  
Soil Water ◽  
Large Scale ◽  
Coal Ash ◽  
Ash Layer

A regionally explicit, global SWI calibration based on ISMN observations

2021 ◽  
Author(s):  
Manolis G. Grillakis
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Large Scale ◽  
Root Zone ◽  
Soil Depth ◽  
European Space Agency ◽  
Soil Layer ◽  
Added Value ◽  
Water Index ◽  
Soil Moisture Data

<p>Remote sensing has proven to be an irreplaceable tool for monitoring soil moisture. The European Space Agency (ESA), through the Climate Change Initiative (CCI), has provided one of the most substantial contributions in the soil water monitoring, with almost 4 decades of global satellite derived and homogenized soil moisture data for the uppermost soil layer. Yet, due to the inherent limitations of many of the remote sensors, only a limited soil depth can be monitored. To enable the assessment of the deeper soil layer moisture from surface remotely sensed products, the Soil Water Index (SWI) has been established as a convolutive transformation of the surface soil moisture estimation, under the assumption of uniform hydraulic conductivity and the absence of transpiration. The SWI uses a single calibration parameter, the T-value, to modify its response over time.</p><p>Here the Soil Water Index (SWI) is calibrated using ESA CCI soil moisture against in situ observations from the International Soil Moisture Network and then use Artificial Neural Networks (ANNs) to find the best physical soil, climate, and vegetation descriptors at a global scale to regionalize the calibration of the T-value. The calibration is then used to assess a root zone related soil moisture for the period 2001 – 2018.</p><p>The results are compared against the European Centre for Medium-Range Weather Forecasts, ERA5 Land reanalysis soil moisture dataset, showing a good agreement, mainly over mid-latitudes. The results indicate that there is added value to the results of the machine learning calibration, comparing to the uniform T-value. This work contributes to the exploitation of ESA CCI soil moisture data, while the produced data can support large scale soil moisture related studies.</p>

Experimental Simulation of Contaminant Deposition on a Film Cooled Turbine Airfoil Leading Edge

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Jason E. Albert ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Large Scale ◽  
Coal Ash ◽  
Leading Edge ◽  
Experimental Simulation ◽  
Model Surface ◽  
Blowing Ratio ◽  
The Difference ◽  
Wax Deposits ◽  
Turbine Airfoils

A significant challenge of utilizing coal-derived synthetic fuels for gas turbine engines is mitigating the adverse effects of fuel-born contaminant deposits on film cooled turbine surfaces. A new experimental technique has been developed that simulates the key physical, but not the chemical, aspects of coal ash deposition on film cooled turbine airfoil leading edges in order to better understand the interaction between film cooling and deposition and to produce improved film cooling designs. In this large-scale wind tunnel facility, the depositing contaminants were modeled with atomized molten wax droplets sized to match the Stokes numbers of coal ash particles in the engine conditions. The sticking mechanism of the molten contaminants to the turbine surfaces was modeled by ensuring the wax droplets remained somewhat molten when they arrived at the cooled model surface. The airfoil model and wax deposits had thermal conductivities such that they matched the Biot numbers of clean and fouled turbine airfoils at engine conditions. The behavior of the deposit growth was controlled by adjusting the mainstream, coolant, and wax solidification temperatures. Simulated deposits were created for a range of test durations, film cooling blowing ratios, and controlling temperatures. Inspection of the resulting deposits revealed aspects of the flow field that augment and suppress deposition. Deposit thickness was found to increase in time until an equilibrium thickness was attained. Blowing ratio and the difference between mainstream and wax solidification temperatures strongly affected characteristics of the deposits. Model surface temperatures greatly reduced under the deposits as they developed.

Renewal of a national soil water management category system and legacy map by data mining methods, digital primary and hydrological soil property maps

2020 ◽  
Author(s):  
Brigitta Szabó ◽  
Annamária Laborczi ◽  
Gábor Szatmári ◽  
Zsófia Bakacsi ◽  
András Makó ◽  
...  
Keyword(s):  
Water Management ◽  
Hydraulic Conductivity ◽  
Soil Water ◽  
Large Scale ◽  
Soil Property ◽  
Spatial Information ◽  
Pedotransfer Functions ◽  
Catchment Scale ◽  
Category System ◽  
Soil Hydraulic

<p>Soil physical properties and soil water regime have been in the focus of soil surveys and mapping in Hungary due to their importance in various environmental processes and hazards, like waterlogging and drought, which endanger extended areas. <br>In the late ‘70s a category system was elaborated for the planning of water management, which was used as the legend of a nationwide map prepared at a scale of 1:500.000. Soils were characterized qualitatively (e.g.: soil with unfavorable water management was defined with low infiltration rate, very low permeability and hydraulic conductivity, and high water retention), without quantification of these features. The category system was also used for creating large-scale (1:10.000) water management maps, which are contained legally by expert’s reports prepared on the subject of drainage, irrigation, liquid manure, sewage or sewage-sludge disposal. These maps were prepared eventually, essentially for individual plots and are not managed centrally and are not available for further applications.<br>Recently a 3D Soil Hydraulic Database was elaborated for Europe at 250 m resolution based on specific pedotransfer functions and soil property maps of SoilGrids. The database includes spatial information on the soil water content at the most frequently used matric potential values, saturated hydraulic conductivity, Mualem-van Genuchten parameters of the moisture retention and hydraulic conductivity curves. Based on similar idea, the work has been continued to produce more accurate and spatially more detailed hydrophysical maps in Hungary by generalizing the applied pedotransfer functions and using national soil reference data and high resolution, novel, digital soil property maps.<br>We initiated a study in order to formalize the built-in soil-landscape model(s) of the national legacy map on water management, together with the quantification of its categories and its potential disaggregation. The relation of the legacy map with the newly elaborated 3D estimations were evaluated at two scales: nationwide with 250 m resolution and at catchment scale with 100 m resolution. Hydrological and primary soil property maps were used as predictor variables. Unsupervised classifications were performed for spatial-thematic aggregation of the soil hydraulic datasets to identify their intrinsic characteristics, which were used for the elaboration of a renewed water management classification. Hydrological interpretation of the categories provided by the optimum classifications has been carried out (i) by their spatial cross-tabulation with the categories of the legacy map and (ii) using the interval estimation of the applied soil hydraulic properties provided for the individual water management categories. Machine learning approaches were used to analyze the information content of the legacy maps’s category system, whose results were used for its disaggregation. Conditionally located random points were sequentially generated for virtual sampling of the legacy map to produce reference information. The disaggregated maps with the legend of the traditional water management classes were produced both on national and catchment level.</p><p>Acknowledgment: The research has been supported by the Hungarian National Research, Development and Innovation Office (NRDI) under grants KH124765, KH126725, the János Bolyai Research Scholarship of the Hungarian Academy of Sciences and the MTA Cloud infrastructure (https://cloud.mta.hu/).</p>

Satellite-Based Radar Interferometry to Estimate Large-Scale Soil Water Depletion from Clay Shrinkage: Possibilities and Limitations

2013 ◽  
Vol 12 (3) ◽  
pp. vzj2012.0098 ◽  
Author(s):  
Bram te Brake ◽  
Ramon F. Hanssen ◽  
Martine J. van der Ploeg ◽  
Gerrit H. de Rooij
Keyword(s):  
Soil Water ◽  
Large Scale ◽  
Radar Interferometry ◽  
Soil Water Depletion ◽  
Water Depletion

scholarly journals Measurement and simulation of the 16/17 April 2010 Eyjafjallajökull volcanic ash layer dispersion in the northern Alpine region

2011 ◽  
Vol 11 (6) ◽  
pp. 2689-2701 ◽  
Author(s):  
S. Emeis ◽  
R. Forkel ◽  
W. Junkermann ◽  
K. Schäfer ◽  
H. Flentje ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Numerical Simulations ◽  
Large Scale ◽  
Scale Model ◽  
Network Data ◽  
Aerosol Layer ◽  
Volcanic Origin ◽  
Southern Germany ◽  
Volcanic Material ◽  
Ash Layer

Abstract. The spatial structure and the progression speed of the first ash layer from the Icelandic Eyjafjallajökull volcano which reached Germany on 16/17 April is investigated from remote sensing data and numerical simulations. The ceilometer network of the German Meteorological Service was able to follow the progression of the ash layer over the whole of Germany. This first ash layer turned out to be a rather shallow layer of only several hundreds of metres thickness which was oriented slantwise in the middle troposphere and which was brought downward by large-scale sinking motion over Southern Germany and the Alps. Special Raman lidar measurements, trajectory analyses and in-situ observations from mountain observatories helped to confirm the volcanic origin of the detected aerosol layer. Ultralight aircraft measurements permitted the detection of the arrival of a second major flush of volcanic material in Southern Germany. Numerical simulations with the Eulerian meso-scale model MCCM were able to reproduce the temporal and spatial structure of the ash layer. Comparisons of the model results with the ceilometer network data on 17 April and with the ultralight aircraft data on 19 April were satisfying. This is the first example of a model validation study from this ceilometer network data.

scholarly journals Investigating bioretention cell performance: A large-scale lysimeter study 

2021 ◽  
Author(s):  
Daniel Green ◽  
Ross Stirling ◽  
Simon De Ville ◽  
Virginia Stovin ◽  
Richard Dawson
Keyword(s):  
Mass Balance ◽  
Soil Water ◽  
Green Infrastructure ◽  
Large Scale ◽  
Water Movement ◽  
Reference Evapotranspiration ◽  
Soil Water Potential ◽  
Cell Performance ◽  
Base Layer ◽  
Bioretention Cell

<div> <p>Sustainable Drainage Systems (SuDS) are a widely adopted approach for managing excess urban runoff by intercepting, retaining and attenuating the flow of water through the built environment, playing a key role in reducing urban flood risk. Vegetated bioretention cells (‘rain gardens’) are one of the most simple, practical and commonly implemented SuDS options and can be easily retrofitted into urban spaces to deal with surface water from paved areas. Although current UK and international guidance provides design guidance for SuDS, no quantitative indications on their hydrological performance are currently available. This study aims to provide evidence to assess the effectiveness of such systems to support optimal implementation of vegetated bioretention cells for stormwater management. </p> </div><div> <p>Four purpose built, large-scale lysimeter experiments (2.0 m x 2.0 m, each divided into two isolated 1.0 m x 2.0 m cell pairs) were designed to provide long-term monitoring data of key hydrological variables and demonstrate the capacity and effectiveness of monitored bioretention systems. The lysimeters were filled with an engineered soil profile consisting of a surface SuDS substrate (700 mm depth) to sustain vegetation growth and store/attenuate flows, and drainage layers (300 mm depth) consisting of a fine gravel transition layer to prevent the movement of fine sediments and a course gravel base layer to allow free drainage into gauged outflow units. </p> </div><div> <p>Each of the lysimeter cells feature a dense sensor network, allowing spatiotemporal soil-atmosphere interactions to be observed and changes in relation to rainfall events to be quantified. Tipping bucket rain gauges situated on each of the lysimeters allow the quantification of local precipitation inflows, which are also analysed in the context of site-wide weather monitoring stations to calculate Penman-Monteith reference evapotranspiration. Outflow from the drainage layer of each lysimeter cell is measured using an outflow gauge. Additionally, a network of in-situ soil sensors were deployed throughout the substrate profile at various depths to quantify soil water movement and changes in volumetric water content, soil temperature, electrical conductivity, soil-water potential and hydrostatic water level in accordance with localised weather conditions. Quantifying inflows, storages and losses allows an understanding of the lysimeter mass balance. Further, each of the lysimeter cell pairs were planted with different planting styles (unvegetated control, reference short grass and two uniform mono-cropped shrub species) to provide differing reference evapotranspiration scenarios and to understand the influence of vegetation on bioretention cell performance.  </p> </div><div> <p>This paper outlines the commissioning of a large-scale lysimeter study at the National Green Infrastructure Facility and presents results from mid-2020 onwards, highlighting the hydrological performance of the bioretention cells under a range of natural storm events and climatic conditions. Lysimeter mass balance and retention efficiencies are presented for each of the vegetation scenarios. Further, differences in soil-water retention ability between the lysimeters are examined in relation to the efficiency of various planting styles and their comparative evapotranspirative behaviour. Working together with a range of stakeholders involved in UK SuDS schemes, this work is helping to inform design criteria and anticipated bioretention cell performance using a quantified evidence base.</p> </div>

scholarly journals Big and small: menisci in soil pores affect water pressures, dynamics of groundwater levels, and catchment-scale average matric potentials

2010 ◽  
Vol 7 (5) ◽  
pp. 6491-6523
Author(s):  
G. H. de Rooij
Keyword(s):  
Soil Water ◽  
Large Scale ◽  
Soil Surface ◽  
Subsurface Water ◽  
Vertical Position ◽  
Pore Scale ◽  
Catchment Scale ◽  
Matric Potential ◽  
Groundwater Levels ◽  
Interface Curvature

Abstract. Soil water is confined behind the menisci of its water-air interface. Catchment-scale fluxes (groundwater recharge, evaporation, transpiration, precipitation, etc.) affect the matric potential, and thereby the interface curvature and the configuration of the phases. In turn, these affect the fluxes (except precipitation), creating feedbacks between pore-scale and catchment-scale processes. Tracking pore-scale processes beyond the Darcy scale is not feasible. Instead, for a simplified system based on the classical Darcy's Law and Laplace-Young Law we i) clarify how menisci transfer pressure from the atmosphere to the soil water, ii) examine large-scale phenomena arising from pore-scale processes, and iii) analyze the relationship between average meniscus curvature and average matric potential. In stagnant water, changing the gravitational potential or the curvature of the air-water interface changes the pressure throughout the water. Adding small amounts of water can thus profoundly affect water pressures in a much larger volume. The pressure-regulating effect of the interface curvature showcases the meniscus as a pressure port that transfers the atmospheric pressure to the water with an offset directly proportional to its curvature. This property causes an extremely rapid rise of phreatic levels in soils once the capillary fringe extends to the soil surface and the menisci flatten. For large bodies of subsurface water, the curvature and vertical position of any meniscus quantify the uniform hydraulic potential under hydrostatic equilibrium. During unit-gradient flow, the matric potential corresponding to the mean curvature of the menisci should provide a good approximation of the intrinsic phase average of the matric potential.

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