Sand Transport and Abrasion within Simulated Standing Vegetation

2017 ◽  
Vol 60 (3) ◽  
pp. 791-802 ◽  
Author(s):  
Howell B. Gonzales ◽  
Mark E. Casada ◽  
Lawrence J. Hagen ◽  
John Tatarko ◽  
Ronaldo G. Maghirang
Keyword(s):  
Wind Speed ◽  
Wind Erosion ◽  
Crop Residues ◽  
Sand Transport ◽  
Vegetation Density ◽  
Threshold Velocity ◽  
Sand Surface ◽  
Bare Sand ◽  
Standing Vegetation ◽  
The Impact

Abstract.Crop residues help protect topsoil from depletion and abrasion due to wind erosion. Limited studies have focused on the type and orientation of canopies that help minimize the effects of erosion by wind. In this study, a series of wind tunnel experiments was conducted to measure sand transport and abrasion energies within simulated standing vegetation. Wind speed profiles, relative abrasion energies, and rates of sand discharge were evaluated during 3 min test runs at two different vegetation heights (150 and 220 mm) for each of three densities of simulated vegetation (i.e., 100 × 200 mm, 200 × 200 mm, and 300 × 200 mm spacing). Tests were also conducted for a bare sand surface. As expected, vegetation density was directly related to threshold velocity and inversely related to sand discharge. The densest configuration (i.e., 100 × 200 mm spacing) increased the threshold velocity of bare sand from 5.9 to 10 m s-1. The presence of vegetation was found to be effective in minimizing the abrasion experienced by the standing vegetation models by lowering the saltation of sand particles that could impact the simulated plants. The coefficient of abrasion (Can), a measure of kinetic energy via the impact of saltating particles, was affected by saltation discharge, although this did not depend on wind speed. The values of Can for all configurations were significantly different (p < 0.05) from the bare sand surface . Keywords: Abrasion energy, Sand discharge, Standing vegetation, Threshold wind velocity, Wind erosion.

scholarly journals Populus simonii Carr. Reduces Wind Erosion and Improves Soil Properties in Northern China

Forests ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 315 ◽  
Author(s):  
Jieming Zhang ◽  
Guodong Jia ◽  
Ziqiang Liu ◽  
Dandan Wang ◽  
Xinxiao Yu
Keyword(s):  
Sediment Transport ◽  
Wind Speed ◽  
Wind Erosion ◽  
Surface Wind ◽  
Chemical Properties ◽  
Stand Density ◽  
Northern China ◽  
Stand Age ◽  
Sand Transport ◽  
Total N

To assess the ecological effects of poplar stands with different densities and ages, fixed observation sites were established in selected standard forest plots. Daily dynamics of wind speed and sand transport rate were monitored over an erosive period (March to June) in 2017. Soil characteristics were also measured at these plots. Average daily wind speed and average daily wind erosion modulus decreased significantly after the establishment of poplar trees on sandy land, while soil density decreased significantly, soil hardness increased greatly, and soil organic carbon, total N, and available P levels increased significantly. With increasing stand density, average daily wind speed and daily sediment transport firstly decreased and then increased, while the investigated soil nutrients showed the opposite trend. A tree density of 1320–1368 trees·hm−2 significantly reduced surface wind erosion. With the increase in forest age, the average daily wind speed and daily sediment transport declined, while soil physical and chemical properties were gradually improved. At a stand age of 40 years, wind-caused soil erosion significantly reduced. Taking these effects into consideration, the design and management of protective forest systems in arid and semi-arid areas can be greatly improved.

scholarly journals Effect of Rainfall Quantity on the Frequency of Severe Dust Storm in Iraq

2019 ◽  
Vol 32 ◽  
pp. 156-170
Author(s):  
Ibrahim I. Mohammed ◽  
Ahmed F. Hassoon
Keyword(s):  
Wind Speed ◽  
Natural Environment ◽  
Dust Storm ◽  
Wind Erosion ◽  
Inverse Relationship ◽  
Research Data ◽  
Dust Storms ◽  
The Impact ◽  
Normal Rainfall ◽  
Climatic Elements

The dust storms and their recurrence are common phenomena in Iraq because it suffers from the exploitation of mankind to the natural environment and to the deterioration of vegetation and soil which responsible to the exposure of the soil to wind erosion leading to dust phenomena. Rain is one of the most influential climatic elements in reducing and minimizing the impact of dust storms. The amount of rainfall in Iraq is relatively small, where most of the year is not rainy. This in turn increases the dryness of the soil and increases the formation of dust storms. In this research data of (visibility, wind speed and direction and total rain amount) from the Iraqi Meteorological Organization and Seismology were analyzed for nine stations spread across the country (Mosul, Kirkuk, Haditha, Baghdad, Rutba, Nukhayb, Najaf, Amara and Nasiriya) for the period from 2001 - 2017 to compare annually severe dust storms with rainy seasons. Drought seasons were also determined using the percent of normal rainfall (PN) method. It was found that there was an inverse relationship between rainfall and severe dust storms, (according to Pearson’s correlation coefficient) where it was noticed that the highest amount of rainfall was in Mosul station with a total of 5231.6mm during the study period with only 6 severe dust storms during the same period. In other hand the lowest amount of rainfall was in Nukhayb station 1304.6mm during the study period with 62 severe dust storms.

Study on Soil Erosion by Wind Tunnel Experiment of Semi-Arid Steppe in Inner Mongolia

2012 ◽  
Vol 518-523 ◽  
pp. 4766-4770
Author(s):  
Lan Gao ◽  
Yu Jun Qiu ◽  
Xue Yong Zou ◽  
Ren De Wang ◽  
Na Zhou
Keyword(s):  
Particle Size ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Soil Erosion ◽  
Moisture Content ◽  
Inner Mongolia ◽  
Erosion Rate ◽  
Wind Erosion ◽  
Sand Transport ◽  
Average Particle

The characteristics of soil erosion of steppe in Inner Mongolia were studied in wind-tunnel tests. The results indicated that the soil in this region consists primarily of sand and coarse silt, with particle sizes mainly between 0.02 and 1mm, and it is defined as erodible sandy soil. The eroded sediments are mainly concentrated at heights of 0~24cm, and the extreme value of particle size is clearly in the range 100~300μm. Average particle size increased with increasing wind speed, and it decreased exponentially in the vertical direction, reflecting the characteristics of sand transport by wind. The relationship between wind erosion rate and wind speed assumes a power function with correlation coefficients greater than 0.9. A wind speed of 15m/s is a significance point above which wind erosion in this region becomes very large. Soil erosion rate decreases logarithmically as soil moisture content and vegetation coverage increase, and the 5% level of moisture content is a turning point.

scholarly journals Postharvest Burning of Crop Residues in Home Stoves in a Rural Site of Daejeon, Korea: Its Impact to Atmospheric Carbonaceous Aerosol

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 257
Author(s):  
Jin Sang Jung ◽  
Ji Hwan Kang
Keyword(s):  
Urban Area ◽  
Rural Area ◽  
Crop Residues ◽  
Sampling Period ◽  
Carbonaceous Aerosol ◽  
Rural Site ◽  
Carbonaceous Aerosols ◽  
High Concentration ◽  
Crop Residue Burning ◽  
The Impact

To investigate the impact of burning postharvest crop residues in home stoves, PM2.5 samples (particulate matter with a diameter of <2.5 μm) were collected every 3 h at a rural site in Daejeon, Korea during the postharvest season in 2014. A high concentration of levoglucosan was observed with a peak value of 3.8 µg/m3 during the sampling period. The average mannosan/levoglucosan ratio (0.18) at the rural site during a severe BB episode (levoglucosan > 1 μg/m3) was similar to burnings of pepper stems (0.19) and bean stems (0.18) whereas the average OC/levoglucosan ratio (9.9) was similar to burning of pepper stems (10.0), implying that the severe BB episode was mainly attributed to burning of pepper stems. A very strong correlation was observed between levoglucosan and organic carbon (OC) (R2 = 0.81) during the entire sampling period, suggesting that the emission of organic aerosols at the rural site was strongly associated with the burning of crop residues in home stoves. The average mannosan/levoglucosan ratio (0.17 ± 0.06) in the rural area was similar to that in a nearby urban area in Daejeon (0.16 ± 0.04). It was concluded that crop residue burning in a home stove for space heating is one of the important sources of carbonaceous aerosols not only in a rural area but also in the urban area of Daejeon, Korea during the postharvest season.

scholarly journals The ground-level ozone concentration is inversely correlated with the number of COVID-19 cases in Warsaw, Poland

2021 ◽  
Author(s):  
Oskar Wiśniewski ◽  
Wiesław Kozak ◽  
Maciej Wiśniewski
Keyword(s):  
Wind Speed ◽  
Ozone Concentration ◽  
Inverse Correlation ◽  
Ground Level ◽  
Viral Agent ◽  
The Novel ◽  
Weather Factors ◽  
Ground Level Ozone ◽  
The Many ◽  
The Impact

AbstractCOVID-19, which is a consequence of infection with the novel viral agent SARS-CoV-2, first identified in China (Hubei Province), has been declared a pandemic by the WHO. As of September 10, 2020, over 70,000 cases and over 2000 deaths have been recorded in Poland. Of the many factors contributing to the level of transmission of the virus, the weather appears to be significant. In this work, we analyze the impact of weather factors such as temperature, relative humidity, wind speed, and ground-level ozone concentration on the number of COVID-19 cases in Warsaw, Poland. The obtained results show an inverse correlation between ground-level ozone concentration and the daily number of COVID-19 cases.

scholarly journals Measurement of the Sea Surface Height with Airborne GNSS Reflectometry and Delay Bias Calibration

2021 ◽  
Vol 13 (15) ◽  
pp. 3014
Author(s):  
Feng Wang ◽  
Dongkai Yang ◽  
Guodong Zhang ◽  
Jin Xing ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Arrival Time ◽  
Elevation Angle ◽  
Satellite System ◽  
Sea Surface Height ◽  
Antenna Pattern ◽  
Sea Surface ◽  
Observation Method ◽  
Global Navigation Satellite ◽  
The Impact

Sea surface height can be measured with the delay between reflected and direct global navigation satellite system (GNSS) signals. The arrival time of a feature point, such as the waveform peak, the peak of the derivative waveform, and the fraction of the peak waveform is not the true arrival time of the specular signal; there is a bias between them. This paper aims to analyze and calibrate the bias to improve the accuracy of sea surface height measured by using the reflected signals of GPS CA, Galileo E1b and BeiDou B1I. First, the influencing factors of the delay bias, including the elevation angle, receiver height, wind speed, pseudorandom noise (PRN) code of GPS CA, Galileo E1b and BeiDou B1I, and the down-looking antenna pattern are explored based on the Z-V model. The results show that (1) with increasing elevation angle, receiver height, and wind speed, the delay bias tends to decrease; (2) the impact of the PRN code is uncoupled from the elevation angle, receiver height, and wind speed, so the delay biases of Galileo E1b and BeiDou B1I can be derived from that of GPS CA by multiplication by the constants 0.32 and 0.54, respectively; and (3) the influence of the down-looking antenna pattern on the delay bias is lower than 1 m, which is less than that of other factors; hence, the effect of the down-looking antenna pattern is ignored in this paper. Second, an analytical model and a neural network are proposed based on the assumption that the influence of all factors on the delay bias are uncoupled and coupled, respectively, to calibrate the delay bias. The results of the simulation and experiment show that compared to the meter-level bias before the calibration, the calibrated bias decreases the decimeter level. Based on the fact that the specular points of several satellites are visible to the down-looking antenna, the multi-observation method is proposed to calibrate the bias for the case of unknown wind speed, and the same calibration results can be obtained when the proper combination of satellites is selected.

scholarly journals Wind speed in spring dominated the decrease in wind erosion across the Horqin Sandy Land in northern China

2021 ◽  
Vol 127 ◽  
pp. 107599
Author(s):  
Hanbing Zhang ◽  
Jian Peng ◽  
Chaonan Zhao ◽  
Zihan Xu ◽  
Jianquan Dong ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Erosion ◽  
Northern China ◽  
Horqin Sandy Land ◽  
Sandy Land

scholarly journals Simulation of Pan-Evaporation Using Penman and Hamon Equations and Artificial Intelligence Techniques

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 793
Author(s):  
Abdul Razzaq Ghumman ◽  
Mohammed Jamaan ◽  
Afaq Ahmad ◽  
Md. Shafiquzzaman ◽  
Husnain Haider ◽  
...  
Keyword(s):  
Wind Speed ◽  
Water Resources ◽  
Arid Regions ◽  
Fuzzy Inference ◽  
Sunshine Duration ◽  
Pan Evaporation ◽  
Estimation Of Parameters ◽  
Inference System ◽  
Daunting Task ◽  
The Impact

The evaporation losses are very high in warm-arid regions and their accurate evaluation is vital for the sustainable management of water resources. The assessment of such losses involves extremely difficult and original tasks because of the scarcity of data in countries with an arid climate. The main objective of this paper is to develop models for the simulation of pan-evaporation with the help of Penman and Hamon’s equations, Artificial Neural Networks (ANNs), and the Artificial Neuro Fuzzy Inference System (ANFIS). The results from five types of ANN models with different training functions were compared to find the best possible training function. The impact of using various input variables was investigated as an original contribution of this research. The average temperature and mean wind speed were found to be the most influential parameters. The estimation of parameters for Penman and Hamon’s equations was quite a daunting task. These parameters were estimated using a state of the art optimization algorithm, namely General Reduced Gradient Technique. The results of the Penman and Hamon’s equations, ANN, and ANFIS were compared. Thirty-eight years (from 1980 to 2018) of manually recorded pan-evaporation data regarding mean daily values of a month, including the relative humidity, wind speed, sunshine duration, and temperature, were collected from three gauging stations situated in Al Qassim, Saudi Arabia. The Nash and Sutcliffe Efficiency (NSE) and Mean Square Error (MSE) evaluated the performance of pan-evaporation modeling techniques. The study shows that the ANFIS simulation results were better than those of ANN and Penman and Hamon’s equations. The findings of the present research will help managers, engineers, and decision makers to sustainability manage natural water resources in warm-arid regions.

scholarly journals Friend or Foe? Impacts of Dietary Xylans, Xylooligosaccharides, and Xylanases on Intestinal Health and Growth Performance of Monogastric Animals

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 609
Author(s):  
Jonathan T. Baker ◽  
Marcos E. Duarte ◽  
Debora M. Holanda ◽  
Sung Woo Kim
Keyword(s):  
Crop Residues ◽  
Structural Difference ◽  
Nutrient Release ◽  
Food Product ◽  
Degree Of Polymerization ◽  
Poultry Production ◽  
Intestinal Health ◽  
Sustainable Food ◽  
And Performance ◽  
The Impact

This paper discusses the structural difference and role of xylan, procedures involved in the production of xylooligosaccharides (XOS), and their implementation into animal feeds. Xylan is non-starch polysaccharides that share a β-(1-4)-linked xylopyranose backbone as a common feature. Due to the myriad of residues that can be substituted on the polymers within the xylan family, more anti-nutritional factors are associated with certain types of xylan than others. XOS are sugar oligomers extracted from xylan-containing lignocellulosic materials, such as crop residues, wood, and herbaceous biomass, that possess prebiotic effects. XOS can also be produced in the intestine of monogastric animals to some extent when exogenous enzymes, such as xylanase, are added to the feed. Xylanase supplementation is a common practice within both swine and poultry production to reduce intestinal viscosity and improve digestive utilization of nutrients. The efficacy of xylanase supplementation varies widely due a number of factors, one of which being the presence of xylanase inhibitors present in common feedstuffs. The use of prebiotics in animal feeding is gaining popularity as producers look to accelerate growth rate, enhance intestinal health, and improve other production parameters in an attempt to provide a safe and sustainable food product. Available research on the impact of xylan, XOS, as well as xylanase on the growth and health of swine and poultry, is also summarized. The response to xylanase supplementation in swine and poultry feeds is highly variable and whether the benefits are a result of nutrient release from NSP, reduction in digesta viscosity, production of short chain xylooligosaccharides or a combination of these is still in question. XOS supplementation seems to benefit both swine and poultry at various stages of production, as well as varying levels of XOS purity and degree of polymerization; however, further research is needed to elucidate the ideal dosage, purity, and degree of polymerization needed to confer benefits on intestinal health and performance in each respective species.

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