Muddy water irrigation, an effective water-saving irrigation method, has been widely used in the Yellow River Basin in China. To investigate the effect of sand content on water infiltration and dense ...layer formation under one-dimensional vertical infiltration of muddy water, muddy water infiltration experiments were performed in the laboratory, and five sand contents of muddy water (5=0%, 3%, 6%, 9%, and 12%) were used. Models were established to describe the relationship between the cumulative infiltration amount I(t) and the infiltration duration (t); the relationship among the migration distance of the wetting front (Z), S, and t; the thickness of the sedimentary layer H(t); and the relationship between S and t. The results revealed that I(t) and Z decreased significantly with the increase of sand contents, while H(t) increased significantly with the increase of sand contents. I(t) and Z were in the range of 7 cm and 20 cm for each treatment, respectively. The variation in I(t) with t fitted Kostiakov and Philip models, and the coefficients of determination were all greater than 0.99. With the increase in 5, the infiltration coefficient gradually decreased, the infiltration index gradually increased, and the sorptivity gradually decreased. The particle composition of the sedimentary layer was similar to that of the argillaceous sediment, and the content of particles with a size of less than 2 mm in the sedimentary layer was lower than that of the argillaceous sediment. Compared with the original soil, the content of particles with a size of less than 0.05 mm and physical clay particles (diameter less than 0.01 mm) in the soil with an infiltration depth of 0-2 cm increased. The retention layer was from the topsoil to the infiltration depth of approximately 2 cm. This study can provide a scientific basis for further research on soil infiltration mechanisms under muddy water.
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FFLJ, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UL, UM, UPUK
Rainwater infiltration is primarily governed by the soil-water characteristic curve (SWCC) and hydraulic conductivity function (HCF) of soil. Both the SWCC and the HCF are hysteretic during the ...drying and wetting processes. In a numerical simulation, different seepage results can be obtained by incorporating different hydraulic conductivity functions of soil. In practice, the wetting HCF is commonly estimated from the wetting SWCC using the statistical method, which is named HCFswcc,w in this note. However, there is no study that has verified the results from seepage analyses using HCFswcc,w. Therefore, the objective of this study is to investigate the influence of wetting SWCC and wetting HCF on 1-D water infiltration. The results from the numerical simulations were verified with the instrumentation reading from a soil column. It was observed that the results from the model using wetting HCFPSDF, which defines the wetting HCF estimated using the concept of pore-size distribution function, gave better agreement with the instrumented data. Therefore, both wetting SWCC and wetting HCFPSDF are advised to be used as input information for the numerical simulation of rainwater infiltration.
The penetration of substances from the surface to deep inside plant tissues is called infiltration. Although various plant tissues may be effectively saturated with externally applied fluid, most ...described infiltration strategies have been developed for leaves. The infiltration process can be spontaneous (under normal atmospheric pressure) or forced by a pressure difference generated between the lamina surface and the inside of the leaf. Spontaneous infiltration of leaf laminae is possible with the use of liquids with sufficiently low surface tension. Forced infiltration is most commonly performed using needle-less syringes or vacuum pumps.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Effects of root and soil water on infiltration rate were studied during different stages.•Root diameter became the main factor affecting soil infiltration along infiltration time.•The ...0–2-mm-diameter root was positively correlated with infiltration rate.•The >4.5-mm-diameter root was negatively correlated with infiltration rate.•Fine roots more determine soil infiltration potential than soil water content.
Soil water is the key limiting factor for achieving sustainable revegetation. Soil infiltration rate plays an important role in determining the inputs from precipitation, which is important for the plant growth and groundwater recharge in semi-arid regions. Soil infiltration rate is generally influenced by belowground biomass (BGB), soil water content (SWC) and other soil properties (total soil porosity, soil mean weight diameter and soil organic carbon). The aim of this study is to understand the effects of plant roots, SWC and other soil properties on soil infiltration rate, and to identify the main factor affecting soil infiltration rate. This study investigated the total soil porosity (TP), soil mean weight diameter (MWD), soil organic carbon (SOC), SWC and plant roots of five grasslands (Bromus inermis, Trifolium repens, Panicum virgatum, Medicago sativa and Miscanthus sinensis). An automatic measurement system of point source device was used to quantify the soil infiltration rate. Results showed that SWC significantly affected the initial infiltration rate (P < 0.05), but plant roots gradually became the main factor affecting soil infiltration rate as the increasing infiltration time. The percentage of root volume (PV) of 0–2 mm was positively correlated with infiltration rate, while the PV of >4.5 mm was negatively correlated with infiltration rate. Our results indicated that fine roots could increase soil organic matters and form soil pores, thus more determining the potential of soil infiltration than soil water content during the short-term vegetation restoration in semi-arid regions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Understanding the hydrological and physical responses of shallow slopes subject to rainfall events is vital for the efficiency of a warning system setup. In this research, a series of experiments ...were undertaken to evaluate the hydrological responses of shallow slopes of varying steepness and when subjected to varying intensities, periods, and inter-storm periods of rainfall. An analysis of infinite slopes was also undertaken to develop a fundamental understanding of rainfall-induced shallow slope failure characteristics. The hydrological and physical responses were characterized in the infiltration and saturation phases. During the infiltration phase, the maximum magnitude of water content was found behind the wetting front, termed as the water content behind the wetting front (θ
wb
). For a certain soil type, the magnitude of θ
wb
was found to be dependent on the magnitude of rainfall intensity, regardless of the slope gradient and initial water content. Based on the relative depth of the failure plane, the failure can be categorized by three prime modes: (i) along the impervious layer mode, (ii) shallow depth mode, and (iii) transitional mode. These modes can be characterized by the magnitude of a stability index termed as
tan
φ
′
/
tan
β
ratio. An infiltration index, termed as i/k
s
ratio, was found to play a role in the depth of the failure plane only for the transitional mode.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Calibration is an essential step for improving
the accuracy of simulations generated using hydrologic models. A key modeling
decision is selecting the performance metric to be optimized. It has been
...common to use squared error performance metrics, or normalized variants such
as Nash–Sutcliffe efficiency (NSE), based on the idea that their
squared-error nature will emphasize the estimates of high flows. However, we
conclude that NSE-based model calibrations actually result in poor
reproduction of high-flow events, such as the annual peak flows that are used
for flood frequency estimation. Using three different types of performance
metrics, we calibrate two hydrological models at a daily step, the Variable
Infiltration Capacity (VIC) model and the mesoscale Hydrologic Model (mHM),
and evaluate their ability to simulate high-flow events for 492 basins
throughout the contiguous United States. The metrics investigated are
(1) NSE, (2) Kling–Gupta efficiency (KGE) and its variants, and (3) annual
peak flow bias (APFB), where the latter is an application-specific metric
that focuses on annual peak flows. As expected, the APFB metric produces the
best annual peak flow estimates; however, performance on other
high-flow-related metrics is poor. In contrast, the use of NSE results in
annual peak flow estimates that are more than 20 % worse, primarily due
to the tendency of NSE to underestimate observed flow variability. On the
other hand, the use of KGE results in annual peak flow estimates that are
better than from NSE, owing to improved flow time series metrics (mean and
variance), with only a slight degradation in performance with respect to
other related metrics, particularly when a non-standard weighting of the
components of KGE is used. Stochastically generated ensemble simulations
based on model residuals show the ability to improve the high-flow metrics,
regardless of the deterministic performances. However, we emphasize that
improving the fidelity of streamflow dynamics from deterministically
calibrated models is still important, as it may improve high-flow metrics
(for the right reasons). Overall, this work highlights the need for a deeper
understanding of performance metric behavior and design in relation to the
desired goals of model calibration.
The accurate measurement of soil infiltration rates is a challenging task in hydrological studies, as they are governed by complex interactions between the plant and soil components. To explore the ...effects of plant roots and soil moisture (SM) on infiltration process, an automatic measurement system based on a point source device was used to determine infiltration rates at different cultivated grasslands (leguminous, gramineous and mixed) in an arid region of China. The results showed that SM and plant roots significantly affected the infiltration process at different stages in the three grasslands. The soil infiltration rates were negatively correlated to SM, but a positive correlation was observed with the below-ground biomass (BGB). SM was the main factor influencing the infiltration rates in the initial stage of infiltration, whereas both SM and BGB determined the steady-state infiltration rates. The influence of the combined effects of SM and plant roots decreased over infiltration time. The decreased rate of determining coefficient showed that SM was more influent than plant roots. These results may contribute to interpret the observed higher soil infiltration capacity in the leguminous grasslands than in the gramineous and the mixed grasslands, and were conducive to better understand the effects of plant and soil properties on infiltration processes in arid areas.
•Soil moisture and plant roots determined soil infiltration capacity by stages were studied.•Soil moisture is a main factor to influence negatively infiltration capacity in initial stage.•Soil moisture and plant roots codetermined the infiltration rate in steady stage.•Influences of soil moisture and roots are diminishing with the duration of infiltration time.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The application of flue gas desulfurization gypsum (FGDG) improves the soil structure, reduces soil pH, and accelerates soil salt leaching. Biochar amendment to soil can affect the soil infiltration ...rate, increase soil porosity, decrease soil bulk density, and enhance the water retention capacity. This study investigated the interactive effect of FGDG and biochar on water infiltration characteristics and physicochemical properties as well as determined the optimal amendment rate as a saline-alkaline soil conditioner. Seven experimental schemes were designed, and the newly reclaimed cultivated soil from Pingtan Comprehensive Experimental Zone in Fujian Province, China, was used in an indoor soil column experiment to simulate soil infiltration. Five models were employed to describe the infiltration process. The power function was used to represent the dynamic process of the wetting front. The conclusions of this study are as follows: (1) there was a reduction in the infiltration capacity of saline-alkaline soil (sandy soil) in each treatment, and the application of FGDG alone had the highest inhibition effect compared to the control (CK). The Kostiakov model provides the best fit for the experimental data of soil cumulative infiltration. (2) All treatments increased the total porosity and water content of saline-alkali soil, with the combined application of FGDG and biochar found to be more effective. (3) The application of FGDG alone or in combination with biochar decreased the pH and increased the electrical conductivity of the saline-alkali soil significantly, with the combined application having the most significant effect. In contrast, soil amended with biochar alone had minimal effect on the pH and EC of the soil. (4) The best improvement ratio was achieved with the F1B2 combination (75 g/kg FGDG + 30 g/kg biochar).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Two 12-year simulations were conducted with the RegCM4 model to study how different hydrology schemes can affect the terrestrial hydrology cycle, the surface energy balance, and the regional climate ...of Africa and in particular tropical Africa. One simulation used the default TOP hydrology scheme in the CLM4.5 land surface model; the other used the variable infiltration capacity (VIC) hydrology model coupled to CLM4.5. The results show that the VIC scheme has a lower soil infiltration rate and hence lower surface soil moisture (10 cm in this study) relative to the default TOP scheme. This leads to a different partitioning of terms in the surface energy balance, with low evapotranspiration and high sensible heat flux, resulting in a net warming effect. The VIC simulation also has low relative humidity due to the low evapotranspiration rate. The low infiltration rate of the VIC hydrology also results in accumulation of moisture on the soil surface. In addition, the VIC scheme generates more precipitation, especially in the summer (JJA) season. Thus, the hydrology parameterization can affect not just the terrestrial hydrology cycle but also energy balance partitioning and hence the surface climate. Moreover, the VIC simulation has smaller biases in the surface energy flux and other surface climate variables in comparison with the default CLM4.5 run. We conclude that the VIC land surface hydrology scheme succeeds in controlling the infiltration rate, the surface soil moisture, and hence total evapotranspiration, which improves the surface energy balance and hence produces a better surface climate. Thus, we recommend the VIC hydrology scheme for future climate studies over Africa.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In last years, many attempts were made to recognize chronic rhinosinusitis with nasal polyps (CRSwNP) phenotypes focusing on identifying relevant key pathogenic molecules. Polyps recurrence rate ...ranges from 4% to 60%, so it's clear that not all clinical and immunologic factors associated with recurrence are known.
We investigate the inflammatory profile in patients with long term recurrent and non-recurrent CRSwNPs and if a specific profile is associated with recurrence, comparing eosinophilic, neutrophilic and lymphocytic infiltration, as well as IL-5 and IL-8 expression to long term recurrence rate.
This prospective study included 44 adult patients with CRSwNP treated with endoscopic sinus surgery between 2008 and 2010. Long term follow-up data (8–10 years) indicated that among 44 patients, 18 (40.1%) experienced long term recurrence of nasal polyposis needing maximal medical treatment or revision surgery. We realized two groups: one with patients who didn't present long term recurrence (26 patients) and another with patients who presented long term recurrence (18 patients) and in both groups eosinophilic, neutrophilic and lymphocytic infiltration and IL-5 and IL-8 expression were measured.
The parameters that reached statistical significance (p < 0.05) comparing the two groups were eosinophilic infiltration and IL-5 expression, whereas neutrophilic and lymphocytic infiltration, as IL-8 expression didn't show any significant difference.
Asthma and aspirin intolerance seemed significantly more frequent in patients with recurrence, while allergy presented not statistically significant difference between two groups.
We can conclude that high eosinophilic infiltration and high IL-5 expression in CRSwNP correlate with higher rate of long term recurrence, while neutrophilic and lymphocytic infiltration, and IL-8 expression don't correlate with it. These findings provide the opportunity to improve our ability to predict the prognosis of surgical intervention, although it is still needed to explore the optimal predictor of outcome in CRSwNP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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