scholarly journals Model predicts the impact of root system architecture on soil water infiltration.

2021 ◽  
Author(s):  
Andrew Mair ◽  
Lionel Xavier Dupuy ◽  
Mariya Ptashnyk
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Root System ◽  
Moisture Transport ◽  
Water Pressure ◽  
Root Systems ◽  
Saturated Hydraulic Conductivity ◽  
Water Infiltration ◽  
Richards Equation ◽  
The Impact

There is strong experimental evidence that root systems substantially change the saturated hydraulic conductivity of soil. However, the mechanisms by which roots affect soil hydraulic properties remain largely unknown. In this work, we made the hypothesis that preferential soil moisture transport occurs along the axes of roots, and that this is what changes a soil's saturated hydraulic conductivity. We modified Richards' equation to incorporate the preferential flow of soil moisture along the axes of roots. Using the finite element method and Bayesian optimisation, we developed a pipeline to calibrate our model with respect to a given root system. When applied to simulated root systems, the pipeline successfully predicted the pore-water pressure profiles corresponding to saturated hydraulic conductivity values, observed by Leung et al. (2018), for soils vegetated by willow and grass. Prediction accuracy improved for root systems with more realistic architectures, therefore suggesting that changes in saturated hydraulic conductivity are a result of roots enabling preferential soil moisture transport along their axes. The model proposed in this work improves our ability to predict moisture transport through vegetated soil and could help optimise irrigation, forecast flood events and plan landslide prevention strategies.

Characterizing and linking macropore structure characteristics to water infiltration in stony soils

2021 ◽  
Author(s):  
Cuiting Dai ◽  
Yiwen Zhou ◽  
Zhaoxia Li ◽  
Tianwei Wang ◽  
Jun Deng
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
Water Pressure ◽  
Saturated Hydraulic Conductivity ◽  
Central China ◽  
Water Infiltration ◽  
Three Gorges Reservoir Area ◽  
X Ray ◽  
Forest Sites ◽  
Macropore Structure

<p>Macropores have been widely recognized as preferential pathways for the rapid movement of water into soils. The objectives of this study were to characterize soil macropore structures using X-ray computed tomography (CT) and to explore the relationships between macropore characteristics and hydraulic properties of stony soils. To achieve these, a total of 18 soil columns were sampled from six sites (three sites covered with grass and three sites with forest) with stony soils located in a mountain watershed in the Three Gorges Reservoir Area of Central China. Field infiltration experiments were carried out at the sampling sites under near-saturated conditions using a tension disc infiltrometer. The three-dimensional macropore structures were visualized from X-ray CT images, and total macroporosity, connected macroporosity, macropore density, specific surface area, degree of anisotropy, fractal dimension, and hydraulic radius were characterized. The results showed that the largest total macroporosity and connected macroporosity were observed at forest sites. The macropore structure with high connectivity could facilitate greater water infiltration into the soils. The near-saturated hydraulic conductivity Kh was significantly higher at the forest sites than at the grassland sites at four water pressure heads. The stony soils studied had heterogenous macropore systems with large and well-connected macropores. The macroporosity of macropores with equivalent diameters between 0.5 and 2 mm was found best to predict the near-saturated hydraulic conductivity. Our study provides a helpful technique for a better understanding of stony soil macropores and hydraulic properties by a combination of 3D visualization methods and traditional hydraulic analysis.</p>

Characterization of Soil Moisture Distribution and Movement Under the Influence of Watering-dewatering Using AHFO and BOTDA Technologies

2019 ◽  
Vol 25 (3) ◽  
pp. 189-202 ◽  
Author(s):  
Ding-Feng Cao ◽  
Bin Shi ◽  
Hong-Hu Zhu ◽  
Chao-Sheng Tang ◽  
Zhan-Pu Song ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Fine Particles ◽  
Water Movement ◽  
Particle Migration ◽  
Moisture Distribution ◽  
Water Infiltration ◽  
Richards Equation ◽  
Laboratory Model ◽  
Soil Moisture Distribution

ABSTRACT The infiltration and distribution of water through unsaturated soil determine its mechanical and hydrological properties. However, there are few methods that can accurately capture the spatial distribution of moisture inside soil. This study aims to demonstrate the use of actively heated fiber optic (AHFO) and Brillouin optical time domain analysis (BOTDA) technologies for monitoring soil moisture distribution as well as strain distribution. In addition to a laboratory model test, finite element analyses were conducted to interpret the measurements. During the experiment, the fine particle migration was also measured to understand its influence on soil hydraulic conductivity. The results of the experiment indicate that (i) for a soil that has never experienced a watering-dewatering cycle, water infiltration can be accurately calculated using the Richards’ equation; (ii) migration of fine soil particles caused by the watering-dewatering cycle significantly increases the hydraulic conductivity; and (iii) two critical zones (drainage and erosion) play significant roles in determining the overall hydraulic conductivity of the entire soil. This study provides a new method for monitoring the changes in soil moisture, soil strain, and hydraulic conductivity. The observations suggest that the effect of fine particles migration should be considered while evaluating soil moisture distribution and water movement.

scholarly journals The impact of different tillage treatments on hydraulic conductivity of loamy soil

2012 ◽  
Vol 60 (5) ◽  
pp. 109-114 ◽  
Author(s):  
Ivana Kameníčková ◽  
L. Larišová ◽  
A. Stoklásková
Keyword(s):  
Hydraulic Conductivity ◽  
Conventional Tillage ◽  
Saturated Hydraulic Conductivity ◽  
Water Infiltration ◽  
Reduced Tillage ◽  
Loamy Soil ◽  
Double Ring ◽  
Unsaturated Hydraulic Conductivity ◽  
The Impact

Water infiltration into the soil profile, surface runoff and soil erosion in arable lands depend on the conditions of the top layer. The tillage treatment of the top layer plays a key role in changes of the hydro-physical properties, mainly saturated hydraulic conductivity Ks of the surface layer. The aim of this study was to asses the impact of different tillage treatments on hydraulic conductivity in the locality Bohaté Málkovice. Field experimental works in this area were performed in 2009 and were repeted in 2011 on Haplic Chernozem, medium heavy loamy soil. The experimental area was divided into two parts; top layer of these plots was cultivated by applying conventional and reduced tillage treatment. Both these plots were sown with spring barley (Hordeum vulgare). For the field measurement of water infiltration into the soil was used double-ring infiltrometer (2009, 2011) and Minidisk infiltrometer (2011). Near the point were the infiltration was measured, the soil samples were always collected for laboratory determination of basic physical properties of soil (bulk density, porosity, initial and saturated water content, aeration of the soil) and saturated hydraulic conductivity Ks. For laboratory determination of Ks was used permeameter with constant gradient.For evaluation of saturated hydraulic conductivity Ks using the double-ring infiltration method was used Philip’s three-parameter equation and for evaluation of unsaturated hydraulic conductivity K(h) using Minidisk infiltrometer was used Zang’s method. After two years of using repeatedly applied different tillage treatments was significantly influenced saturated hydraulic conductivity Ks. The Ks value increased approximately six times for reduced tillage and more than three times for conventional tillage. Laboratory determined average values of Ks were compared with the average estimates of Ks from infiltration tests. The results were burdened by a number of errors (compaction, preferential flow). These mean values were higher for conventional and reduced tillage. Unsaturated hydraulic conductivity K(−2cm) for reduced tillage was higher, for conventional tillage decreased approximately three times.

scholarly journals Predicting the impact of biochar on the saturated hydraulic conductivity of natural and engineered media

2021 ◽  
Vol 295 ◽  
pp. 113143
Author(s):  
Yudi Yan ◽  
Seyyed Ali Akbar Nakhli ◽  
Jing Jin ◽  
Godfrey Mills ◽  
Clinton S. Willson ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
The Impact

The Study of Surfactant Effect on Soil Water Infiltration

2011 ◽  
Vol 361-363 ◽  
pp. 1946-1949
Author(s):  
Yi Fei Li ◽  
Tian Wei Qian ◽  
Li Juan Huo
Keyword(s):  
Hydraulic Conductivity ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Saturated Hydraulic Conductivity ◽  
Water Infiltration ◽  
Ammonium Bromide ◽  
Soil Infiltration ◽  
Soil Water Infiltration ◽  
Dodecyl Benzene Sulfonate ◽  
Cetyl Trimethyl Ammonium

In this paper,the effect of surfactant to the infiltration and the change of saturated hydraulic conductivity was studied by GUELPH PERMEAMETER. We investigated effects on soil infiltration by three representative surfactants.The results show that the existing of sodium dodecyl benzene sulfonate (SDBS), cetyl trimethyl ammonium bromide bromide (CTAB) and polyxyethylene fatty alcohol (AEO9) would decrease soil saturated hydraulic conductivity.

Impact of an Exponential Profile of Saturated Hydraulic Conductivity within the ISBA LSM: Simulations over the Rhône Basin

2006 ◽  
Vol 7 (1) ◽  
pp. 61-80 ◽  
Author(s):  
B. Decharme ◽  
H. Douville ◽  
A. Boone ◽  
F. Habets ◽  
J. Noilhan
Keyword(s):  
High Resolution ◽  
Hydraulic Conductivity ◽  
Land Surface ◽  
Large Scale ◽  
Saturated Hydraulic Conductivity ◽  
Rooting Depth ◽  
Surface Model ◽  
Low Resolution ◽  
The Impact ◽  
Hydrological Applications

Abstract This study focuses on the influence of an exponential profile of saturated hydraulic conductivity, ksat, with soil depth on the water budget simulated by the Interaction Soil Biosphere Atmosphere (ISBA) land surface model over the French Rhône River basin. With this exponential profile, the saturated hydraulic conductivity at the surface increases by approximately a factor of 10, and its mean value increases in the root zone and decreases in the deeper region of the soil in comparison with the values given by Clapp and Hornberger. This new version of ISBA is compared to the original version in offline simulations using the Rhône-Aggregation high-resolution database. Low-resolution simulations, where all atmospheric data and surface parameters have been aggregated, are also performed to test the impact of the modified ksat profile at the typical scale of a climate model. The simulated discharges are compared to observations from a dense network consisting of 88 gauging stations. Results of the high-resolution experiments show that the exponential profile of ksat globally improves the simulated discharges and that the assumption of an increase in saturated hydraulic conductivity from the soil surface to a depth close to the rooting depth in comparison with values given by Clapp and Hornberger is reasonable. Results of the scaling experiments indicate that this parameterization is also suitable for large-scale hydrological applications. Nevertheless, low-resolution simulations with both model versions overestimate evapotranspiration (especially from the plant transpiration and the wet fraction of the canopy) to the detriment of total runoff, which emphasizes the need for implementing subgrid distribution of precipitation and land surface properties in large-scale hydrological applications.

Surface-positioned double-ring to improve traditional infiltrometer for measuring soil infiltration

Soil Research ◽  
2020 ◽  
Vol 58 (3) ◽  
pp. 314
Author(s):  
Jing Zhang ◽  
Shaopeng Li
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Accuracy ◽  
Soil Column ◽  
Saturated Hydraulic Conductivity ◽  
Experimental Results ◽  
Water Infiltration ◽  
Maximum Relative Error ◽  
Wetting Front ◽  
Double Ring ◽  
Improve Measurement

The installation of a traditional double-ring infiltrometer (DRI) into soil is difficult and time consuming. It results in reduced accuracy because of soil disturbance and water leakage along the gaps between the ring wall and the soil. In this study, a surface-positioned DRI (SPDRI) was suggested to improve measurement accuracy and convenience of the DRI. Laboratory experiments were conducted to evaluate performance of the method in terms of the influence of the lateral flow of water on the accuracy of infiltration rate, average vertical wetting front depth and saturated hydraulic conductivity. A cylindrical soil column was used to simulate the ideal ring infiltrometer (IRI) of the one-dimensional vertical infiltration process for comparison purposes. Experimental results indicated that the infiltration rates measured by the SPDRI and IRI were nearly identical, with maximum relative error (RE) of 18.75%. The vertical wetting front depth of the SPDRI was nearly identical to that of the IRI, with proportional coefficients of 0.97 and R2 > 0.95. Comparison of the soil saturated hydraulic conductivity with those from IRI indicated that the REs were 7.05–10.63% for the SPDRI. Experimental results demonstrated that the SPDRI could improve the measurement accuracy and facilitate the soil water infiltration measurement process.

Novel 3D imaging of root systems grown in slab-shaped rhizotrons

2020 ◽  
Author(s):  
Sarah Bereswill ◽  
Nicole Rudolph-Mohr ◽  
Christian Tötzke ◽  
Nikolay Kardjilov ◽  
André Hilger ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Root System ◽  
3D Imaging ◽  
Neutron Radiography ◽  
Root Systems ◽  
Root System Architecture ◽  
Moisture Distribution ◽  
Ph Gradients ◽  
Non Invasive ◽  
Soil Moisture Distribution

<p>Complex plant-soil interactions can be visualized and quantified by combined application of different non-invasive imaging techniques. Oxygen, carbon dioxide and pH gradients in the rhizosphere can be observed with fluorescent planar optodes, while neutron radiography detects small-scale heterogeneities in soil moisture and its dynamics. Respiration and exudation rates can vary between roots of different types, such as primary and lateral roots, as well as along single roots among the same plant. The 3D root system architecture is therefore a key information when studying rhizosphere processes. It can be captured in detail with neutron tomography, but so far only for plants grown in small, cylindrical containers.</p><p>Combined non-invasive imaging of biogeochemical dynamics, soil moisture distribution and 3D root system architecture is a technical challenge. Thin, slab-shaped rhizotrons with relatively large vertical and lateral extension are well suited for optical fluorescence imaging, allowing for spatially extended observation of biogeochemical patterns. This rhizotron geometry is, however, unfavorable for standard 3D tomography due to reconstruction artefacts triggered by insufficient neutron transmission when the long side of the sample is aligned parallel to the beam direction.</p><p>We therefore applied neutron laminography, a method where the rotational axis is tilted, to measure the root systems of maize and lupine plants grown in slab-shaped glass rhizotrons (length = 150 mm, width = 150 mm, depth = 15 mm) in 3D. In parallel, we investigated rhizosphere oxygen dynamics and pH value via fluorescence imaging and assessed soil moisture distribution with neutron radiography.</p><p>Neutron laminography enabled the 3D reconstruction of the root systems with a nominal spatial resolution of 100 µm/pixel. Reconstruction quality strongly depended on root-soil contrast and hence soil moisture level. After reconstruction of the root system and co-registration with the fluorescence images, first results indicate that observed oxygen concentrations and pH gradients depend on root type and individual distance of the roots from the planar optode.</p><p>In conclusion, neutron laminography is a novel 3D imaging method for root-soil systems grown in slab-shaped rhizotrons. The method allows for determining the precise 3D position of individual roots within the rhizotron and can be combined with 2D imaging approaches. Following experiments will address X-ray laminography as a possible attractive further application.</p>

COMPARISON OF METHODS FOR DETERMINING SATURATED HYDRAULIC CONDUCTIVITY AND DRAINABLE POROSITY OF TWO SOUTHERN ALBERTA SOILS

1986 ◽  
Vol 66 (2) ◽  
pp. 249-259 ◽  
Author(s):  
G. D. BUCKLAND ◽  
D. B. HARKER ◽  
T. G. SOMMERFELDT
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Characteristic Curve ◽  
Subsurface Drainage ◽  
Saturated Hydraulic Conductivity ◽  
Drainage Design ◽  
Moisture Characteristic ◽  
Constant Head ◽  
Subsurface Drains ◽  
Drainable Porosity

Saturated hydraulic conductivity (Ks) and drainable porosity (f) determined by different methods and for different depths were compared with those determined from the performance of drainage systems installed at two locations. These comparisons were made to determine which methods are suitable for use in subsurface drainage design. Auger hole and constant-head well permeameter Ks were 140 and 110%, respectively, of Ks determined from subsurface drains. Agreement of horizontal or vertical Ks, from in situ falling-head permeameters; to other methods was satisfactory providing sample numbers were large. Ks by Tempe cells was only 3–10% of drain Ks and in one instance was significantly lower than Ks determined by all other methods. At one site a profile-averaged value of f determined from the soil moisture characteristic curve (0–5 kPa) of semidisturbed cores agreed with that determined from drainage trials. At the other site, a satisfactory value of f was found only when the zone in which the water table fluctuated was considered. Results indicate that Ks determined by the auger hole and constant-head well permeameter methods, and f determined from the soil moisture characteristic curve of semidisturbed cores, are sufficiently reliable and practical for subsurface drainage design. Key words: Subsurface drainage, hydraulic conductivity, drainable porosity

Sign in / Sign up

Export Citation Format

Share Document