Field studies of water and salt movement in an irrigated swelling clay soil. III. Salt movement during ponding

Soil Research ◽  
1982 ◽  
Vol 20 (2) ◽  
pp. 101 ◽  
Author(s):  
DS McIntyre ◽  
J Loveday ◽  
CL Watson
Keyword(s):  
Clay Soil ◽  
Field Studies ◽  
In Situ Measurements ◽  
Swelling Clay ◽  
Before And After ◽  
Plough Layer ◽  
Water And Salt Movement

The effect of gypsum, incorporated into the plough layer of a saline, sodic, clay profile, on the leaching of salt, was determined from both in situ measurements, and from chloride determinations using samples taken before and after ponding. Observed differences in leaching patterns are attributed to water in the treated profile moving through interpedal macropores as well as through micropores within the peds (or matrix), but only through micropores in the untreated profile. The efficiency of the two mechanisms is discussed.

Field studies of water and salt movement in an irrigated swelling clay soil. I. Infiltration during ponding

Soil Research ◽  
1982 ◽  
Vol 20 (2) ◽  
pp. 81 ◽  
Author(s):  
DS McIntyre ◽  
J Loveday ◽  
CL Watson
Keyword(s):  
Clay Soil ◽  
New South ◽  
Infiltration Rate ◽  
Field Studies ◽  
Deep Percolation ◽  
Soil Infiltration ◽  
Swelling Clay ◽  
South Wales ◽  
Plough Layer ◽  
Water And Salt Movement

Infiltration and deep percolation were measured during ponding of a saline sodic cracking clay soil, commonly used for rice production in the Riverina of New South Wales. Because gypsum may be used to ameliorate this soil for row cropping, the effect of incorporating gypsum into the plough layer was determined. Without gypsum, 292mm water infiltrated in 379 days of ponding, wetting the profile to approximately 2.1 m. In contrast when gypsum was incorporated in the plough layer, 605 mm of water infiltrated in 145 days, and water had penetrated beyond 4.5 m in 57 days. In the latter case, sufficient water percolated below 2.0m to raise the groundwater level by as much as 10m. The infiltration rate for the unameliorated soil was similar to values determined by others; for the ameliorated soil, infiltration behaviour was more like that of non-sodic self-mulching grey or brown clays, and raises questions regarding the amount of deep percolation when rice is grown on such soils.

Field studies of water and salt movement in an irrigated swelling clay soil. II. Profile hydrology during ponding

Soil Research ◽  
1982 ◽  
Vol 20 (2) ◽  
pp. 91 ◽  
Author(s):  
DS McIntyre ◽  
J Loveday ◽  
CL Watson
Keyword(s):  
Hydraulic Conductivity ◽  
Clay Soil ◽  
Field Studies ◽  
Wetting Front ◽  
Steady State Flow ◽  
Untreated Soil ◽  
Swelling Clay ◽  
Treated Soil ◽  
Treated Plot ◽  
Water And Salt Movement

Two plots on a saline sodic cracking clay soil, to one of which gypsum was applied at 10 t/ha, were instrumented to 4.5 m from a pit, in order to observe wetting patterns during extended inundation. On the gypsum-treated plot the wetting front was diffuse. Water content increased simultaneously within quite large depth intervals, and two distinct wetting phases were detected to a depth of 2.7 m. The change in water potential with time showed the same pattern. Once steady-state flow had been reached, tensiometer-pressure potentials were positive except between 0.55 and 1.50 m. In contrast, the untreated soil exhibited a better defined wetting front which moved slowly down the profile. Only in the upper 0.55 m were two distinct wetting phases discernible; tensiometer-pressure potentials were generally lower than for the gypsum-treated soil, and remained negative throughout the ponding period except at 0.25 m. This behaviour, and the estimated values of hydraulic conductivity, suggest that, in the ameliorated soil, water penetrated and moved through the profile mainly in macropores associated with structure, and that, in the unameliorated soil, such flow was largely prevented by a region of low hydraulic conductivity between 0.25 and 0.55 m.

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

Shrinkage and swelling of clay soil. Comparison between laboratory and in situ measurements

2011 ◽  
Vol 15 (5) ◽  
pp. 819-838
Author(s):  
Céline Andrieux ◽  
Marie Chrétien ◽  
Alain Denis ◽  
Richard Fabre ◽  
Jean-François Lataste
Keyword(s):  
Clay Soil ◽  
In Situ Measurements ◽  
Shrinkage And Swelling

scholarly journals Direct impact of solar farm deployment on surface longwave radiation

2021 ◽  
Author(s):  
Chongxing Fan ◽  
Xianglei Huang
Keyword(s):  
Land Surface ◽  
Climate Models ◽  
Longwave Radiation ◽  
In Situ Measurements ◽  
Solar Panels ◽  
Land Type ◽  
Before And After ◽  
Moderate Resolution ◽  
Split Window Algorithm

Abstract Motivated by a previous study of using the Moderate Resolution Imaging Spectroradiometers (MODIS) observations to quantify changes in surface shortwave spectral reflectances caused by six solar farms in the southwest United States, here we used a similar method to study the longwave effects of the same six solar farms, with emphases on surface emissivities and land surface temperature (LST). Two MODIS surface products were examined: one relying on generalized split-window algorithm while assuming emissivities from land cover classifications (MYD11A2), the other based on Temperature Emissivity Separation algorithm capable of dynamically retrieving emissivities (MYD21A2). Both products suggest that, compared to adjacent regions without changes before and after solar farm constructions, the solar farm sites have reduced outgoing radiances in three MODIS infrared window channels. Such reduction in upward longwave radiation is consistent with previous in-situ measurements. The MYD11A2 results show constant emissivities before and after solar farm constructions because its land type classification algorithm is not aware of the presence of solar farms. The estimated daytime and nighttime LST reduction due to solar farm deployment are ~1-4K and ~0.2-0.9K, respectively. The MYD21A2 results indicate a decrease in Band 31 (10.78-11.28 µm) emissivity up to −0.01 and little change in Band 32 (11.77-12.27 µm) emissivity. The LST decreases in the MYD21A2 is slightly smaller than its counterpart in the MYD11A2. Laboratory and in-situ measurements indicate the longwave emissivity of solar panels can be as low as 0.83, considerably smaller than MODIS retrieved surface emissivity over the solar farm sites. The contribution of exposed and shaded ground within the solar farm to the upward longwave radiation needs to be considered to fully explain the results. A synthesis of MODIS observations and published in-situ measurements is presented. Implication for parameterizing such solar farm longwave effect in the climate models is also discussed.

Measuring air-filled porosity changes in an irrigated swelling clay soil

Soil Research ◽  
1985 ◽  
Vol 23 (1) ◽  
pp. 15 ◽  
Author(s):  
NS Jayawardane ◽  
WS Meyer
Keyword(s):  
Moisture Content ◽  
Clay Soil ◽  
Soil Bulk Density ◽  
Swelling Clay ◽  
Volumetric Moisture Content ◽  
Neutron Count ◽  
Destructive Measurement ◽  
Non Destructive ◽  
Good Agreement

An in-situ method for measuring air filled porosity (�a) of soils using a neutron meter was developed and evaluated for a layered, swelling clay soil. Bulk density-volumetric moisture content relationships of soil layers were used to calculate the regressions of volumetric moisture content on �a. These regressions were combined with calibration equations of the neutron meter to obtain relationships between �a and neutron counts. The �a values predicted from measured neutron count ratios show good agreement with �a values calculated from the measured bulk densities and moisture contents in a transitional red-brown earth. The method provides a rapid and non-destructive measurement of �a. Soil aeration in a transitional red-brown earth under two irrigation treatments was assessed using neutron counts to monitor the changes in �a profiles. Large soil cores which were flooded had lower profile �a values than did cores which were not flooded. However, differences were small, owing apparently to the very low rates of infiltration and redistribution. The potential use of this method to continuously monitor changes in �a profiles allows frequent calculation of aeration stress indices, which may be used to predict crop responses and yield losses due to poor aeration.

The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

2019 ◽  
Author(s):  
Michael Stukel ◽  
Thomas Kelly
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Transport Model ◽  
California Current ◽  
In Situ Measurements ◽  
Power Law Distribution ◽  
Sinking Particles ◽  
Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

Post-Hurricane Michael damage assessment using ADCIRC storm surge hindcast, image classification, and LiDAR

Shore & Beach ◽  
2019 ◽  
pp. 3-14 ◽  
Author(s):  
Joshua Davis ◽  
Diana Mitsova ◽  
Tynon Briggs ◽  
Tiffany Briggs
Keyword(s):  
Wave Energy ◽  
Field Studies ◽  
Feedback Mechanism ◽  
Water Velocity ◽  
Airborne Lidar ◽  
Storm Events ◽  
Magnetic Current ◽  
Coastal Mapping ◽  
Electro Magnetic

Wave forcing from hurricanes, nor’easters, and energetic storms can cause erosion of the berm and beach face resulting in increased vulnerability of dunes and coastal infrastructure. LIDAR or other surveying techniques have quantified post-event morphology, but there is a lack of in situ hydrodynamic and morphodynamic measurements during extreme storm events. Two field studies were conducted in March 2018 and April 2019 at Bethany Beach, Delaware, where in situ hydrodynamic and morphodynamic measurements were made during a nor’easter (Nor’easter Riley) and an energetic storm (Easter Eve Storm). An array of sensors to measure water velocity, water depth, water elevation and bed elevation were mounted to scaffold pipes and deployed in a single cross-shore transect. Water velocity was measured using an electro-magnetic current meter while water and bed elevations were measured using an acoustic distance meter along with an algorithm to differentiate between the water and bed during swash processes. GPS profiles of the beach face were measured during every day-time low tide throughout the storm events. Both accretion and erosion were measured at different cross-shore positions and at different times during the storm events. Morphodynamic change along the back-beach was found to be related to berm erosion, suggesting an important morphologic feedback mechanism. Accumulated wave energy and wave energy flux per unit area between Nor’easter Riley and a recent mid-Atlantic hurricane (Hurricane Dorian) were calculated and compared. Coastal Observations: JALBTCX/NCMP emergency-response airborne Lidar coastal mapping & quick response data products for 2016/2017/2018 hurricane impact assessments

Sign in / Sign up

Export Citation Format

Share Document