scholarly journals Biological soil crusts cause subcritical water repellency in a sand dune ecosystem located along a rainfall gradient in the NW Negev desert, Israel

2016 ◽  
Vol 64 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Hannes Keck ◽  
Vincent John Martin Noah Linus Felde ◽  
Sylvie Laureen Drahorad ◽  
Peter Felix-Henningsen
Keyword(s):  
Subcritical Water ◽  
Water Drop ◽  
Water Repellency ◽  
Biological Soil Crusts ◽  
Water Repellent ◽  
Rainfall Gradient ◽  
Soil Crusts ◽  
Water Redistribution ◽  
Local Water ◽  
Wilhelmy Plate Method

AbstractThe biological soil crusts (BSCs) in the NW Negev cause local water redistribution by increasing surface runoff. The effects of pore clogging and swelling of organic and inorganic crust components were intensively investigated in earlier studies. However, the effect of water repellency (WR) was not addressed systematically yet. This study investigates subcritical WR of BSCs in three different study sites in the NW Negev. For this purpose, three common methods to determine soil WR were used: (i) the repellency index (RI) method (ii) the water drop penetration time (WDPT) test and (iii) the Wilhelmy plate method (WPM). Furthermore, the potential influence of WR on local water redistribution is discussed and the applied methods are compared. We found the BSC to be subcritically water repellent. The degree of WR may only affect water redistribution on a microscale and has little influence on the ecosystem as a whole. The RI method was clearly the most appropriate to use, whereas the WDPT and the WPM failed to detect subcritical WR.

scholarly journals Quantifying the effect of subcritical water repellency on sorptivity : a physically based model

2021 ◽  
Author(s):  
Rose Shillito ◽  
Markus Berli ◽  
Teamrat Ghezzehei
Keyword(s):  
Contact Angle ◽  
Hydraulic Conductivity ◽  
Subcritical Water ◽  
Water Drop ◽  
Water Repellency ◽  
Quantitative Model ◽  
Saturated Hydraulic Conductivity ◽  
Silica Sand ◽  
Water Repellent ◽  
Burned Areas

Soil water wettability or water repellency is a phenomenon that can affect infiltration and, ultimately, runoff. Thus, there is a need to develop a model that can quantitatively capture the influence of water repellency on infiltration in a physically meaningful way and within the framework of existing infiltration theory. The analytical model developed in this study relates soil sorptivity (an infiltration parameter) with contact angle (a direct measure of water repellency) for variably saturated media. The model was validated with laboratory experiments using a silica sand of known properties treated to produce controlled degrees of water repellency. The measured contact angle and sorptivity values closely matched the model‐predicted values. Further, the relationship between the frequently used water drop penetration time test (used to assess water repellency) and sorptivity was illustrated. Finally, the direct impact of water repellency on saturated hydraulic conductivity was investigated due to its role in infiltration equations and to shed light on inconsistent field observations. It was found that water repellency had minimal effect on the saturated hydraulic conductivity of structureless sand. A quantitative model for infiltration incorporating the effect of water repellency is particularly important for post‐fire hydrologic modeling of burned areas exhibiting water repellent soils.

Ongoing succession of biological soil crusts increases water repellency — a case study on Arenosols in Sekule, Slovakia

Biologia ◽  
2013 ◽  
Vol 68 (6) ◽  
Author(s):  
Sylvie Drahorad ◽  
Daniel Steckenmesser ◽  
Peter Felix-Henningsen ◽  
Ľubomír Lichner ◽  
Marek Rodný
Keyword(s):  
Soil Surface ◽  
Water Repellency ◽  
Biological Soil Crusts ◽  
Water Infiltration ◽  
Water Conductivity ◽  
Surface Stability ◽  
Surface Protection ◽  
Soil Crusts ◽  
Surface Sealing ◽  
Successional Stages

AbstractAfter soil surface disturbances biological soil crusts (BSC) cover rapidly the topmost soil millimeters. Depending on BSC age, development of soil water repellency, water infiltration and soil surface stability are influenced by this thin surface sealing. Within this study disturbed, early- mid- and late successional stages of BSC development were examined along a recovery transect. The results show an increase in water repellency and a decrease in water sorptivity and conductivity with ongoing BSC succession. Penetration resistance data shows very stable thin surface protection by cyanobacteria in early successional BSC that is non-repellent. Later successional stages show increased water repellency and lower water conductivity. We conclude that BSC development induces changes in surface structure and wettability. The soil surface wettability is strongly linked to the BSC community composition.

scholarly journals Soil water repellency changes with depth and relationship to physical properties within wettable and repellent soil profiles

2017 ◽  
Vol 65 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Nasrollah Sepehrnia ◽  
Mohammad Ali Hajabbasi ◽  
Majid Afyuni ◽  
Ľubomír Lichner
Keyword(s):  
Organic Matter ◽  
Soil Water ◽  
Subcritical Water ◽  
Water Repellency ◽  
Moisture Distribution ◽  
Water Repellent ◽  
Soil Profiles ◽  
Soil Water Repellency ◽  
Major Property ◽  
Dry Water

AbstractThis study explored the effect of soil water repellency (SWR) on soil hydrophysical properties with depth. Soils were sampled from two distinctly wettable and water repellent soil profiles at depth increments from 0-60 cm. The soils were selected because they appeared to either wet readily (wettable) or remain dry (water repellent) under field conditions. Basic soil properties (MWD, SOM, θv) were compared to hydrophysical properties (Ks, Sw, Se, Sww, Swh, WDPT, RIc, RImand WRCT) that characterise or are affected by water repellency. Our results showed both soil and depth affected basic and hydrophysical properties of the soils (p <0.001). Soil organic matter (SOM) was the major property responsible for water repellency at the selected depths (0-60). Water repellency changes affected moisture distribution and resulted in the upper layer (0-40 cm) of the repellent soil to be considerably drier compared to the wettable soil. The water repellent soil also had greater MWDdryand Ks over the entire 0-60 cm depth compared to the wettable soil. Various measures of sorptivity, Sw, Se, Sww, Swh, were greater through the wettable than water repellent soil profile, which was also reflected in field and dry WDPT measurements. However, the wettable soil had subcritical water repellency, so the range of data was used to compare indices of water repellency. WRCT and RImhad less variation compared to WDPT and RIc. Estimating water repellency using WRCT and RIm indicated that these indices can detect the degree of SWR and are able to better classify SWR degree of the subcritical-repellent soil from the wettable soil.

Water Repellency of Biological Soil Crusts and Influencing Factors on the Southeast Fringe of the Tengger Desert, North-Central China

Soil Science ◽  
2014 ◽  
Vol 179 (9) ◽  
pp. 424-432 ◽  
Author(s):  
Haotian Yang ◽  
Lichao Liu ◽  
Xinrong Li ◽  
Yongping Wei ◽  
Xiaojun Li ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Water Repellency ◽  
Biological Soil Crusts ◽  
Central China ◽  
Tengger Desert ◽  
North Central ◽  
Soil Crusts ◽  
The Tengger Desert

scholarly journals The hydrological role of biological topsoil crusts and water repellency in sandy dry-land areas

2018 ◽  
Vol 36 ◽  
pp. 33-44
Author(s):  
Aaron Yair ◽  
Ram Almog ◽  
Youval Arbel
Keyword(s):  
Water Regime ◽  
Water Repellency ◽  
Annual Rainfall ◽  
Striking Difference ◽  
Water Repellent ◽  
Runoff Generation ◽  
Rainfall Gradient ◽  
Large Trees ◽  
Average Annual Rainfall

Dryland areas are regarded as highly sensitive to climatic changes. A positive relationship between rainfall and environmental factors is often assumed for areas with an average annual rainfall of 100–300 mm. This assumption disregards the fact that a climate change in arid areas is not limited to climatic factors. It is often accompanied by a pronounced spatial variability in surface characteristics. The present work deals with the complex relationships among average annual rainfall, surface properties and the spatial redistribution of water resources in sandy areas located in the Northern Negev Desert. Two case studies are considered. The first deals with the hydrological effects of biological topsoil crusts on the water regime, along a rainfall gradient (86–170 mm). This study is based on five monitoring sites. Data obtained show a decrease in water availability with increasing annual rainfall. The findings are attributed to the decisive role played by the non-uniform properties of the topsoil crust along the rainfall gradient. The second case refers to the non-uniform development, and survival, of planted trees. Trees planted on steep dunes are well developed, with a high survival rate, whereas trees planted on low angle dunes are small. This study focused on the role of a water repellent layer on the water regime. Data obtained show a striking difference between steep and low dunes in all aspects studied, namely the degree of water repellency, frequency and magnitude of runoff events, infiltration depth and soil moisture. All variables monitored were found higher on steep than on low dunes. The large trees shed a substantial amount of leaves, whose decay developed a water repellent layer. Runoff generation over the repellent layer enhanced deep water penetration, through the process of subsurface flow. The lack of a water repellent layer over the low dunes prevented runoff generation, with its positive effects.

scholarly journals Effect of kaolinite and Ca-montmorillonite on the alleviation of soil water repellency

2011 ◽  
Vol 50 (No. 8) ◽  
pp. 358-363 ◽  
Author(s):  
P. Dlapa ◽  
S.H. Doerr ◽  
Ľ. Lichner ◽  
M. Šír ◽  
M. Tesař
Keyword(s):  
Water Drop ◽  
Water Repellency ◽  
Silica Sand ◽  
Water Repellent ◽  
Mineral Surfaces ◽  
Adhesion Forces ◽  
Key Factors ◽  
High Adhesion ◽  
Phase Water ◽  
Amphiphilic Organic Compounds

The effects of adding 1&ndash;3% (weight) kaolinite or Ca-montmorillonite on the wettability of silica sand, made highly water repellent with stearic acid, was studied during wetting and prolonged drying phases at 50&deg;C. The persistence of water repellency was estimated with the water drop penetration time (WDPT) test. After wetting water repellency disappeared in all the samples. During the drying phase, water repellency re-appeared in all samples (untreated and clay-treated) as the water content decreased below 1%. Repellency did, however, not reach pre-wetting levels. The effect of clay additions on water repellency differed strongly between the two clay types. Kaolinite reduced WDPT, while Ca-montmorillonite caused an increase in WDPT in the already highly repellent sand. Potential mechanisms for the alleviation effectiveness of kaolinite are proposed, with key factors being the high adhesion forces between water and clay mineral surfaces, and the ability kaolinite to disperse. In the case of Ca-montmorillonite, its lower affinity for water may lead to a displacement of water molecules at mineral surfaces by amphiphilic organic compounds, which may result in increased repellency. This phenomenon clearly requires further investigation.

scholarly journals Testing soil water repellency in a Sicilian area two years after a fire

2019 ◽  
Author(s):  
Vincenzo Bagarello ◽  
Giuseppe Basile ◽  
Gaetano Caltabellotta ◽  
Giuseppe Giordano ◽  
Massimo Iovino
Keyword(s):  
Soil Water ◽  
Water Drop ◽  
Soil Layer ◽  
Soil Surface ◽  
Water Repellency ◽  
Soil Conditions ◽  
Small Scale ◽  
Water Repellent ◽  
Soil Water Repellency ◽  
Mountain Area

The water drop penetration time (WDPT) technique was applied in 2018 to check persistence of soil water repellency (SWR) in a Sicilian mountain area affected by a wildfire on June 2016. A total of four sites, that were severely water repellent immediately after burning, were sampled. Depending on the site, wettable soil conditions, less SWR and maintenance of a noticeable SWR were detected two years later. At the site showing a near-constant SWR, WDPTs were particularly high in the top soil layer (0-0.03 m) and they appreciably decreased more in depth. Signs of decreasing SWR in drier soil conditions and in association with coarser soil particles were also detected at this site. High gradients of the WDPT can occur at very small vertical distances and a depth increment of approximately 0.01 m should be appropriate to capture small-scale vertical changes in SWR, especially close to the soil surface. Occurrence of SWR phenomena is easily perceivable and explainable if an inverse relationship between WDPTs and antecedent soil water content is obtained. A direct relationship between these two variables is more difficult to interpret because infiltration times that increase in wetter soil are expected according to the classical infiltration theory. A hypothesis that should be tested in the future is to verify if WDPTs that decrease in drier soil conditions signal less SWR as a consequence of a reduced biological activity of the soil. Finally, long-term monitoring projects on longevity of fire effects on SWR should be developed, even because an in depth knowledge of the involved processes is relevant for the civil protection system.

The effect of slash burning on the water repellency of forest soils at Vancouver, British Columbia

1983 ◽  
Vol 13 (2) ◽  
pp. 353-355 ◽  
Author(s):  
G. S. Henderson ◽  
D. L. Golding
Keyword(s):  
Soil Water ◽  
Water Drop ◽  
Water Repellency ◽  
Water Repellent ◽  
Soil Water Repellency ◽  
Naturally Occurring ◽  
And Control ◽  
Water Repellence ◽  
Slash Burning ◽  
Control Samples

Soil from 10 slash burned and 3 unburned clear-cuts was tested for water repellency by the water drop penetration method and compared with naturally occurring soil water repellency in uncut mature forest. There was no difference in soil water repellency between unburned clear-cuts and the uncut forest control. Soil was more frequently water repellent in slash burned sites (35% of samples) than in the control sites (21% of samples), but differences were significant only for the first 2 years after burning. All humus samples were severely water repellent. At the 0- to 4-cm depth below the humus, burned samples were more frequently repellent than control samples, but there was no difference at the 8- to 10-cm and 15+ cm depths. Water repellence decreased with depth in both burned and control sites.

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