Hydraulic properties of a duplex soil determined from in situ measurements

Soil Research ◽  
1987 ◽  
Vol 25 (1) ◽  
pp. 1 ◽  
Author(s):  
MA Rab ◽  
ST Willatt ◽  
KA Olsson
Keyword(s):  
Water Management ◽  
Hydraulic Conductivity ◽  
Soil Water ◽  
Crop Production ◽  
Hydraulic Properties ◽  
Surface Soil ◽  
In Situ Measurements ◽  
Soil Hydraulic Conductivity ◽  
Good Agreement

The hydraulic conductivity characteristics of a duplex soil profile were determined in the field from in situ measurements. For a given soil water suction, hydraulic conductivity of the subsoil was generally lower than the surface soil. Hydraulic conductivity characteristics calculated using the equations of Marshall and Millington and Quirk were in good agreement with field-measured hydraulic conductivity after matching at low soil water suctions. Implications of hydraulic properties for crop production and water management are noted.

Hydraulic properties of a red-brown earth determined from in situ measurements

Soil Research ◽  
1978 ◽  
Vol 16 (2) ◽  
pp. 169 ◽  
Author(s):  
KA Olsson ◽  
CW Rose
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
In Situ Measurements ◽  
Swelling Properties ◽  
Swelling Soils ◽  
Field Check ◽  
Measured Change ◽  
Water Contents ◽  
Good Agreement

Hydraulic conductivity characteristics are described for the soil profile of a red-brown earth exhibiting swelling properties. These were determined from in situ measurements of water content and suction during the redistribution of water following the irrigation of a non-vegetated field plot. Greater water contents were required for the same hydraulic conductivity in the subsoil than for the surface soil below cultivation depth. At a given suction, hydraulic conductivity was generally lower in the subsoil. In a field check on the theory of hydrostatics in swelling soils, values of the overburden potential (�) were derived from theory in terms of readily measurable parameters; these were shown to be in good agreement with values determined independently from the measured change in soil-water suction following the removal of overburden.

The influence of microplastic on soil hydraulic properties

2020 ◽  
Author(s):  
Patrizia Hangele ◽  
Katharina Luise Müller ◽  
Hannes Laermanns ◽  
Christina Bogner
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Pore Space ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
Soil Water Retention ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

<p>The need to study the occurrence and effects of microplastic (MP) in different ecosystems has become apparent by a variety of studies in the past years. Until recently, research regarding MP in the environment has mainly focused on marine systems. Within terrestrial systems, studies suggest soils to be the biggest sink for MP. Some studies now started to explore the presence of MP in soils. However, there is a substantial lack of the basic mechanistic understanding of the behaviour of MP particles within soils.</p><p>This study investigates how the presence of MP in soils affects their hydraulic properties. In order to understand these processes, experiments are set up under controlled laboratory conditions as to set unknown influencing variables to a minimum. Different substrates, from simple sands to undisturbed soils, are investigated in soil cylinders. MP particles of different sizes and forms of the most common plastic types are applied to the surface of the soil cylinders and undergo an irrigation for the MP particles to infiltrate. Soil-water retention curves and soil hydraulic conductivity are measured before and after the application of MP particles. It is hypothesised that the infiltrated MP particles clog a part of the pore space and should thus reduce soil hydraulic conductivity and change the soil-water retention curve of the sample. Knowledge about the influence of MP on soil hydraulic properties are crucial to understand transport and retention of MP in soils.</p>

scholarly journals Error Propagation from Remotely Sensed Surface Soil Moisture Into Soil Water Index Using an Exponential Filter

10.29007/kvhb ◽  
2018 ◽  
Author(s):  
Domenico De Santis ◽  
Daniela Biondi
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Error Propagation ◽  
Surface Soil ◽  
Root Zone ◽  
In Situ Measurements ◽  
Surface Soil Moisture ◽  
Water Index ◽  
Study Sites

In this study an error propagation (EP) scheme was introduced in parallel to exponential filter computation for soil water index (SWI) estimation. A preliminarily assessment of the computed uncertainties was carried out comparing satellite-derived SWI and reference root-zone in situ measurements. The EP scheme has shown skills in detecting potentially less reliable SWI values in the study sites, as well as a better understanding of the exponential filter shortcomings. The proposed approach shows a potential for SWI evaluation, providing simultaneous estimates of time-variant uncertainty.

scholarly journals From near-surface to root-zone soil moisture using an exponential filter: an assessment of the method based on in-situ observations and model simulations

2008 ◽  
Vol 12 (6) ◽  
pp. 1323-1337 ◽  
Author(s):  
C. Albergel ◽  
C. Rüdiger ◽  
T. Pellarin ◽  
J.-C. Calvet ◽  
N. Fritz ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Surface Soil ◽  
Root Zone ◽  
Synthetic Data ◽  
Surface Soil Moisture ◽  
Data Set ◽  
Water Index ◽  
In Situ Observations

Abstract. A long term data acquisition effort of profile soil moisture is under way in southwestern France at 13 automated weather stations. This ground network was developed in order to validate remote sensing and model soil moisture estimates. In this paper, both those in situ observations and a synthetic data set covering continental France are used to test a simple method to retrieve root zone soil moisture from a time series of surface soil moisture information. A recursive exponential filter equation using a time constant, T, is used to compute a soil water index. The Nash and Sutcliff coefficient is used as a criterion to optimise the T parameter for each ground station and for each model pixel of the synthetic data set. In general, the soil water indices derived from the surface soil moisture observations and simulations agree well with the reference root-zone soil moisture. Overall, the results show the potential of the exponential filter equation and of its recursive formulation to derive a soil water index from surface soil moisture estimates. This paper further investigates the correlation of the time scale parameter T with soil properties and climate conditions. While no significant relationship could be determined between T and the main soil properties (clay and sand fractions, bulk density and organic matter content), the modelled spatial variability and the observed inter-annual variability of T suggest that a weak climate effect may exist.

Method for Quick Prediction of Hydraulic Conductivity and Soil-Water Retention of Unsaturated Soils

2018 ◽  
Vol 2672 (52) ◽  
pp. 108-117 ◽  
Author(s):  
Shaoyang Dong ◽  
Yuan Guo ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Characteristic Curve ◽  
Soil Water Retention

Hydraulic conductivity and soil-water retention are two critical soil properties describing the fluid flow in unsaturated soils. Existing experimental procedures tend to be time consuming and labor intensive. This paper describes a heuristic approach that combines a limited number of experimental measurements with a computational model with random finite element to significantly accelerate the process. A microstructure-based model is established to describe unsaturated soils with distribution of phases based on their respective volumetric contents. The model is converted into a finite element model, in which the intrinsic hydraulic properties of each phase (soil particle, water, and air) are applied based on the microscopic structures. The bulk hydraulic properties are then determined based on discharge rate using Darcy’s law. The intrinsic permeability of each phase of soil is first calibrated from soil measured under dry and saturated conditions, which is then used to predict the hydraulic conductivities at different extents of saturation. The results match the experimental data closely. Mualem’s equation is applied to fit the pore size parameter based on the hydraulic conductivity. From these, the soil-water characteristic curve is predicted from van Genuchten’s equation. The simulation results are compared with the experimental results from documented studies, and excellent agreements were observed. Overall, this study provides a new modeling-based approach to predict the hydraulic conductivity function and soil-water characteristic curve of unsaturated soils based on measurement at complete dry or completely saturated conditions. An efficient way to measure these critical unsaturated soil properties will be of benefit in introducing unsaturated soil mechanics into engineering practice.

scholarly journals Validation of aerosol backscatter profiles from Raman lidar and ceilometer using balloon-borne measurements

2021 ◽  
Vol 21 (3) ◽  
pp. 2267-2285
Author(s):  
Simone Brunamonti ◽  
Giovanni Martucci ◽  
Gonzague Romanens ◽  
Yann Poltera ◽  
Frank G. Wienhold ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Aerosol Size Distribution ◽  
Spatial And Temporal Variability ◽  
Raman Lidar ◽  
Backscatter Coefficient ◽  
Custom Made ◽  
Aerosol Backscatter ◽  
Good Agreement

Abstract. Remote-sensing measurements by light detection and ranging (lidar) instruments are fundamental for the monitoring of altitude-resolved aerosol optical properties. Here we validate vertical profiles of aerosol backscatter coefficient (βaer) measured by two independent lidar systems using co-located balloon-borne measurements performed by Compact Optical Backscatter Aerosol Detector (COBALD) sondes. COBALD provides high-precision in situ measurements of βaer at two wavelengths (455 and 940 nm). The two analyzed lidar systems are the research Raman Lidar for Meteorological Observations (RALMO) and the commercial CHM15K ceilometer (Lufft, Germany). We consider in total 17 RALMO and 31 CHM15K profiles, co-located with simultaneous COBALD soundings performed throughout the years 2014–2019 at the MeteoSwiss observatory of Payerne (Switzerland). The RALMO (355 nm) and CHM15K (1064 nm) measurements are converted to 455 and 940 nm, respectively, using the Ångström exponent profiles retrieved from COBALD data. To account for the different receiver field-of-view (FOV) angles between the two lidars (0.01–0.02∘) and COBALD (6∘), we derive a custom-made correction using Mie-theory scattering simulations. Our analysis shows that both lidar instruments achieve on average a good agreement with COBALD measurements in the boundary layer and free troposphere, up to 6 km altitude. For medium-high-aerosol-content measurements at altitudes below 3 km, the mean ± standard deviation difference in βaer calculated from all considered soundings is −2 % ± 37 % (−0.018 ± 0.237 Mm−1 sr−1 at 455 nm) for RALMO−COBALD and +5 % ± 43 % (+0.009 ± 0.185 Mm−1 sr−1 at 940 mm) for CHM15K−COBALD. Above 3 km altitude, absolute deviations generally decrease, while relative deviations increase due to the prevalence of air masses with low aerosol content. Uncertainties related to the FOV correction and spatial- and temporal-variability effects (associated with the balloon's drift with altitude and different integration times) contribute to the large standard deviations observed at low altitudes. The lack of information on the aerosol size distribution and the high atmospheric variability prevent an accurate quantification of these effects. Nevertheless, the excellent agreement observed in individual profiles, including fine and complex structures in the βaer vertical distribution, shows that under optimal conditions, the discrepancies with the in situ measurements are typically comparable to the estimated statistical uncertainties in the remote-sensing measurements. Therefore, we conclude that βaer profiles measured by the RALMO and CHM15K lidar systems are in good agreement with in situ measurements by COBALD sondes up to 6 km altitude.

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