scholarly journals Run duration effects on the hydrodynamic properties of a loam soil estimated by steady-state infiltration methods

2020 ◽  
Author(s):  
Vincenzo Bagarello ◽  
Sonia Maria David
Keyword(s):  
Steady State ◽  
Total Duration ◽  
Infiltration Rate ◽  
Water Volume ◽  
Hydrological Process ◽  
Infiltration Process ◽  
Long Run ◽  
Loam Soil ◽  
Water Volumes ◽  
Ks Values

Steady-state methods of analysis of single-ring infiltration data are commonly applied but the duration of an infiltrometer experiment is often established quite subjectively under the premise that, generally, infiltration stabilizes rather quickly in the field. For a loam soil, the effect of the duration of a beerkan run on sorptivity, S, and saturated hydraulic conductivity, Ks, was tested by using the BEST (Beerkan Estimation of Soil Transfer parameters)-steady and SSBI (Steady version of the Simplified method based on a Beerkan Infiltration run) methods of data analysis. The standard experiment, based on a total of 15 water volumes each establishing an initial ponding depth of ~0.01 m (on average, 0.32 hours of infiltration), yielded approximately two and >100 times higher S and Ks values, respectively, than a long run (117 water volumes or 8.1 hours). Stabilization was faster for S (approximately in 3 hours) than Ks (6 hours). Similar Ks values were obtained with BEST-steady (192-261 mm/h) and the SSBI method (177-184 mm/h) for the standard run but not for the long-duration run (1.5-2.1 and 20-21 mm/h, respectively). This discrepancy was due to the fact that more information on the infiltration process is used by BEST-steady (total duration, total infiltrated water, steady-state infiltration rate) than the SSBI method (only the latter variable). In conclusion, Ks estimates are very sensitive to the used water volume for the run. The run duration should not only depend on attainment of near steadiness but also on the possibility to capture the soil’s hydraulic behavior in a representative situation for the hydrological process of interest. The possibility to use the hydrodynamic soil properties determined with the tested methodology to simulate rainfall effects on soil structure should be tested in the near future.

scholarly journals Source shape and data analysis procedure effects on hydraulic conductivity of a sandy-loam soil determined by ponding infiltration runs

2017 ◽  
Vol 48 (2) ◽  
pp. 71 ◽  
Author(s):  
Vincenzo Bagarello ◽  
Andrea De Santis ◽  
Giuseppe Giordano ◽  
Massimo Iovino
Keyword(s):  
Steady State ◽  
Hydraulic Conductivity ◽  
Sandy Loam ◽  
Analysis Procedure ◽  
Sandy Loam Soil ◽  
Second Phase ◽  
General Validity ◽  
Equivalent Radius ◽  
Loam Soil ◽  
Ks Values

Performing ponding infiltration runs with non-circular sources could represent a good means to sample completely an area of interest. Regardless of the shape of the source, predicting the expected reliability of the collected data by infiltrometers should facilitate soil hydraulic characterisation and also allow a more conscious use of the field data. The influence of the shape of the infiltration source (i.e., circular or square) and the analysis procedure of the steady-state infiltration data on the saturated hydraulic conductivity, Ks, of a sandy-loam soil was tested in this investigation. Circular and square surfaces sampled with the pressure infiltrometer (PI) yielded similar estimates of Ks (i.e., differing by a factor of 1.05-1.16, depending on the calculation method) when an equivalent radius was considered to geometrically describe the square source. With the simplified falling head (SFH) technique, the shape of the source was irrelevant (i.e., circular and square sources yielding Ks values that differed by a factor of 1.19), as theoretically expected. For the steady-state PI experiment, the twoponding depth approach yielded two times smaller Ks values than the one-ponding depth (OPD) approach, probably due to lower steady-state flow rates than those expected for the second phase of the two-level run. The conclusions were that: i) simple infiltrometer experiments (PI, SFH) can be carried out with square sources; and ii) the simplest PI run (OPD approach) is expected to yield the most reliable predictions of Ks. Sampling other soils is advisable in an attempt to make these conclusions of general validity.

Assessment of variability of soil Infiltration Characteristics in Forage Cover

2020 ◽  
Vol 7 (03) ◽  
Author(s):  
AKRAM AHMED ◽  
A. K. PAL ◽  
V. K. PANDEY ◽  
MAHENDRA PRASAD ◽  
ASHUTOSH UPADHYAYA
Keyword(s):  
Steady State ◽  
Sandy Loam ◽  
Infiltration Rate ◽  
Panicum Maximum ◽  
Soil Infiltration ◽  
Infiltration Rates ◽  
Bare Land ◽  
Physically Based ◽  
Loam Soil ◽  
Horton Model

In India, very limited knowledge of soil infiltration characteristics in forages are available. In this study, infiltration characteristics of land covered by six forages have been studied with respect to bare land in sandy loam soil. Two empirical (Kostiakov and Horton) and two physically-based (Phillip and Green‒Ampt) models have been employed to estimate infiltration characteristics and compared with observed field infiltration data. The steady-state infiltration rates measured in forages and bare land were significantly (p less than 0.05) different. The highest average steady-state infiltration rate was measured in Panicum maximum (9.00 cm h-1) followed by TSH (7.40 cm h-1) and least was recorded in Cenchrus ciliaris (2.65 cm h-1) whereas the average steady-state infiltration rate recorded for bare land was 1.90 cm h-1. Results showed that the Kostiakov and Phillip model simulated the field infiltration characteristics with higher accuracy than the two other models except for Chrysopogonfulvus and bare land in which the Horton model outperformed other models. Higher steady-state infiltration rates in forages were attributed to more porosity measured in the soils under forages as compared to bare land.

scholarly journals An automated microinfiltrometer to measure small-scale soil water infiltration properties

2014 ◽  
Vol 62 (3) ◽  
pp. 248-252 ◽  
Author(s):  
Dennis C. Gordon ◽  
Paul D. Hallett
Keyword(s):  
Sandy Loam ◽  
Bubble Formation ◽  
Glass Tube ◽  
Infiltration Rate ◽  
Sandy Loam Soil ◽  
Water Infiltration ◽  
Water Volume ◽  
Small Scale ◽  
Clay Loam ◽  
Loam Soil

Abstract We developed an automated miniature constant-head tension infiltrometer that measures very small infiltration rates at millimetre resolution with minimal demands on the operator. The infiltrometer is made of 2.9 mm internal radius glass tube, with an integrated bubbling tower to maintain constant negative head and a porous mesh tip to avoid air-entry. In the bubbling tower, bubble formation and release changes the electrical resistance between two electrodes at the air-inlet. Tests were conducted on repacked sieved sands, sandy loam soil and clay loam soil, packed to a soil bulk density ρd of 1200 kg m-3 or 1400 kg m-3 and tested either air-dried or at a water potential ψ of -50 kPa. The change in water volume in the infiltrometer had a linear relationship with the number of bubbles, allowing bubble rate to be converted to infiltration rate. Sorptivity measured with the infiltrometer was similar between replicates and showed expected differences from soil texture and ρd, varying from 0.15 ± 0.01 (s.e.) mm s-1/2 for 1400 kg m-3 clay loam at ψ = -50 kPa to 0.65 ± 0.06 mm s-1/2 for 1200 kg m-3 air dry sandy loam soil. An array of infiltrometers is currently being developed so many measurements can be taken simultaneously.

scholarly journals Experimental study on infiltration pattern: opportunities for sustainable management in the Northern region of India

2021 ◽  
Author(s):  
Vikram Kumar ◽  
Barkha Chaplot ◽  
Padam Jee Omar ◽  
Shaktibala S. ◽  
H. Md. Azamathulla
Keyword(s):  
Land Use ◽  
Soil Water ◽  
Process Development ◽  
Average Rate ◽  
Wide Spectrum ◽  
Infiltration Rate ◽  
Northern Region ◽  
Water Infiltration ◽  
Hydrological Process ◽  
Infiltration Process

Abstract The infiltration process plays a key role in designing groundwater recharge, irrigation, and drainage systems, and contamination evaluation is controlled by numerous factors, among which soil physical properties and land use & land cover (LULC) are the prime factors. A comprehensive understanding of the spatial water infiltration characteristics over the soil which is site-specific and more complex due to non-uniformity could enhance the agriculture water use efficiency and mitigate water-related issues. The present study deals with the measurement of field infiltration characteristics using a mini disc infiltrometer in all 24 blocks of Gaya districts, Bihar, which covers a wide spectrum of soil types. Results showed that the average cumulative infiltration rate (IR) for the study area varies between 0.38 and 2.20 cm/min with an average rate of 1.16 cm/min. The initial IR among all blocks was found to be high but decreased gradually with each successive reading. Moreover, the land use under forest cumulative IR was more than the cumulative IR for urban and grassland. Eight blocks (33.3%) have an IR more than the average infiltration of the area which is good for storing the water in the aquifer and suggested constructing a recharge structure. Further investigation revealed a small IR in the inundated area, because of the maximum soil water table. The ready-to-use map showing the IR for the district is prepared which could be used by any decision-taking during the high or low rainfall, understanding the hydrological process, development of any reference guide for farmers for increasing the agriculture productivity and soil-water management.

Spray Volume, Canopy Density, and Other Factors Involved in Thinner Efficacy

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 553d-553
Author(s):  
C.R. Unrath
Keyword(s):  
Tree Height ◽  
Tree Canopy ◽  
Tree Size ◽  
Water Volume ◽  
Canopy Density ◽  
The North ◽  
Run Off ◽  
Tree Canopies ◽  
Average Water ◽  
Water Volumes

Historically, most airblast chemical applications to apple orchards used a single “average” water volume, resulting in variability of coverage with tree size and also the greatest variable in chemical thinning. This coverage variability can be eliminated by properly quantifying the tree canopy, as tree row volume (TRV), and relating that volume to airblast water rate for adequate coverge. Maximum typical tree height, cross-row limb spread, and between-row spacing are used to quantify the TRV. Further refinement is achieved by adjusting the water volume for tree canopy density. The North Carolina TRV model allows a density adjustment from 0.7 gal/1000 ft3 of TRV for young, very open tree canopies to 1.0 gal/1000 ft3 of TRV for large, thick tree canopies to deliver a full dilute application for maximum water application (to the point of run-off). Most dilute pesticide applications use 70% of full dilute to approach the point of drip (pesticide dilute) to not waste chemicals and reduce non-target environmental exposure. From the “chemical load” (i.e., lb/acre) calculated for the pesticide dilute application, the proper chemical load for lower (concentrate) water volumes can be accurately determined. Another significant source of variability is thinner application response is spray distribution to various areas of the tree. This variability is related to tree configuration, light, levels, fruit set, and natural thinning vs. the need for chemical thinning. Required water delivery patterns are a function of tree size, form, spacing, and density, as well as sprayer design (no. of nozzles and fan size). The TRV model, density adjustments, and nozzle patterns to effectively hit the target for uniform crop load will be addressed.

The Olympic Games as a News Shock

2017 ◽  
Vol 19 (6) ◽  
pp. 884-906 ◽  
Author(s):  
Viktoria C. E. Langer ◽  
Wolfgang Maennig ◽  
Felix Richter
Keyword(s):  
Steady State ◽  
Olympic Games ◽  
Structural Models ◽  
Adjustment Process ◽  
Dynamic Adjustment ◽  
Economic Variables ◽  
Long Run ◽  
News Shock ◽  
Steady State Levels ◽  
The Olympic Games

The awarding of the Olympic Games to a certain city or the announcement of a city’s Olympic bid may be considered as a news shock that affects agents’ market expectations. A news shock implies potential impacts on the dynamic adjustment process that change not only the volatility but also the long-run steady-state levels of endogenous economic variables. In this study, we contribute to and extend previous researchers’ attempts to empirically test for the Olympic Games as a news shock by implementing full structural models and by matching Olympic hosts and bidders to structurally similar countries.

The top-heavy shape of authoritarian bureaucracy: evidence from Russia and China

2021 ◽  
pp. 002085232110588
Author(s):  
Tao Li ◽  
Zhenyu M. Wang
Keyword(s):  
Steady State ◽  
Soviet Union ◽  
Rent Seeking ◽  
Tournament Theory ◽  
The Soviet Union ◽  
Long Run ◽  
Public Sector Reforms ◽  
Micro Level ◽  
Heavy Structure ◽  
Theory Framework

The prevalence of top-heavy bureaucracies in non-democracies cannot be explained by the theories of Parkinson, Tullock, Niskanen, or Simon or by classical managerial theories. When bureaucracy positions carry rents, the competition for promotion becomes a rent-seeking process. Borrowing the career-tournament theory framework from managerial scholarship, we argue that top-heavy bureaucracy resembles a tournament with too many finalists. When rent is centralized at the top (i.e. power centralization), as is the case in many non-democracies, the optimal bureaucracy should be top-heavy, accommodating and encouraging relatively more finalists at the top to compete for the final big prize. We provide suggestive evidence by analyzing ministry organizations in China (1993–2014) and Russia (2002–2015). After some fluctuations, the shape of Russian ministries eventually converged with that of China. In the steady state, their ministry shapes are far more top-heavy than what is prescribed by managerial theories. At the micro-level, ministry power centralization, measured by the perceived influence of the ministers, is correlated with ministry top-heaviness in Russia. Points for practitioners Our theory suggests that a top-heavy authoritarian bureaucratic structure naturally follows from a back-loaded sequential career tournament and an effort-maximizing bureaucratic leader. Our findings also suggest that Chinese and Russian ministries both converge to a highly top-heavy structure in the long run. We demonstrate that the top-heavy structure first arose during the planned-economy experiment in the Soviet Union. Our research sheds new light on public-sector reforms that aim to reduce bureaucracy top-heaviness in autocracies.

scholarly journals ENDOGENOUS BORROWING CONSTRAINTS AND WEALTH INEQUALITY

2016 ◽  
Vol 20 (6) ◽  
pp. 1413-1431 ◽  
Author(s):  
Joydeep Bhattacharya ◽  
Xue Qiao ◽  
Min Wang
Keyword(s):  
Steady State ◽  
Credit Market ◽  
Wealth Inequality ◽  
Borrowing Constraints ◽  
Initial Distribution ◽  
The Other ◽  
Capital Investments ◽  
Loan Default ◽  
Long Run ◽  
Human Capital Investments

This paper studies the evolution of wealth inequality in an economy with endogenous borrowing constraints. In the model economy, young agents need to borrow to finance human capital investments but cannot commit to repaying their loans. Creditors can punish defaulters by banishing them permanently from the credit market. At equilibrium, loan default is prevented by imposing a borrowing limit tied to the borrower's inheritance. The heterogeneity in inheritances translates into heterogeneity in borrowing limits: endogenously, some borrowers face a zero borrowing limit, and some are partly constrained, whereas others are unconstrained. Depending on the initial distribution of inheritances, it is possible that all lineages are attracted either to the zero-borrowing-limit steady state or to the unconstrained-borrowing steady state—long-run equality. It is also possible that some lineages end up in one steady state and the rest in the other—complete polarization.

scholarly journals Ponding time in infiltration process for different land use

2021 ◽  
Vol 930 (1) ◽  
pp. 012054
Author(s):  
I K Hidayati ◽  
Suhardjono ◽  
D Harisuseno ◽  
A Suharyanto
Keyword(s):  
Land Use ◽  
Physical Properties ◽  
River Basin ◽  
Sugar Cane ◽  
Infiltration Rate ◽  
Soil Types ◽  
Land Uses ◽  
Infiltration Process ◽  
Double Ring ◽  
Density Values

Abstract Ponding time is the period from the beginning of rainfall/infiltration until the occurrence of ponding. This paper aims to determine the infiltration rate and ponding time on different land uses, such as open fields, residential, agriculture, and vegetation. This research was conducted in one of the watersheds in the Brantas River Basin, namely the Lesti River Basin, which is administratively included in the Malang Regency, East Java. The Lesti River is one of the tributaries of the Brantas River, which originates around Mount Semeru, a very intensive area for planting rice, sugar cane, and coffee. Infiltration data were collected at 35 points using a double-ring infiltrometer spread across the Lesti watershed with Andosol, Mediterranean, and Regosol soil types. At the same time, ponding time was obtained from infiltration measurements in the field using the flooding method. The physical properties of the soils were tested in the laboratory to obtain water content, porosity, and bulk density values. This study resulted in the infiltration rate and ponding time for each land use and shows how the physical properties of the soil affect the ponding time.

A model of unsteady-state transvascular fluid and protein transport in the lung

1984 ◽  
Vol 56 (5) ◽  
pp. 1389-1402 ◽  
Author(s):  
R. J. Roselli ◽  
R. E. Parker ◽  
T. R. Harris
Keyword(s):  
Steady State ◽  
Interstitial Fluid ◽  
Transport Theory ◽  
Fluid Pressure ◽  
Water Volume ◽  
Free Fluid ◽  
Base Line ◽  
Unsteady State ◽  
Total Change ◽  
Organ Systems

Models of steady-state fluid and solute transport in the microcirculation are used primarily to characterize filtration and permeability properties of the transport barrier. Important transient relationships, such as the rate of fluid accumulation in the tissue, cannot be predicted with steady-state models. In this paper we present three simple models of unsteady-state fluid and protein exchange between blood plasma and interstitial fluid. The first treats the interstitium as a homogeneous well-mixed compliant compartment, the second includes an interstitial gel, and the third allows for both gel and free fluid in the interstitium. Because we are primarily interested in lung transvascular exchange we used the multiple-pore model and pore sizes described by Harris and Roselli (J. Appl. Physiol.: Respirat . Environ. Exercise Physiol. 50: 1–14, 1981) to characterize the microvascular barrier. However, the unsteady-state transport theory presented here should apply to other organ systems and can be used with different conceptual models of the blood-lymph barrier. For a step increase in microvascular pressure we found good agreement between theoretical and experimental lymph flow and lymph concentrations in the sheep lung when the following parameter ranges were used: base-line interstitial volume, 150–190 ml; interstitial compliance, 7–10 ml/Torr; initial interstitial fluid pressure, -1 Torr; pressure in initial lymphatics, -5 to -6 Torr; and conductivity of the interstitium and lymphatic barrier, 4.25 X 10(-4) ml X s-1 X Torr-1. Based on these values the model predicts 50% of the total change in interstitial water volume occurs in the first 45 min after a step change in microvascular pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

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