Simulating preferential flow in a two water worlds framework

2020 ◽  
Author(s):  
Jesse Radolinski ◽  
Luke Pangle ◽  
Julian Klaus ◽  
Durelle Scott ◽  
Ryan Stewart
Keyword(s):  
Soil Structure ◽  
Preferential Flow ◽  
Rainfall Intensity ◽  
Isotopic Analysis ◽  
Soil Matrix ◽  
Physical Separation ◽  
Soil Material ◽  
Immobile Water ◽  
Structure Treatment ◽  
Mountain Grasslands

<p>Ecohydrological separation has been observed across climates and biomes, and at a fundamental level suggests that water in mobile versus immobile domains may resist mixing over varying periods of time; however little mechanistic evidence exists to explain this separation at a process scale. Non-equilibrium flow in the vadose zone may partially account for widespread perception of distinct hydrological domains yet no studies have weighed its contribution. Using a simple isotope mixing technique, we sought to determine the amount of preferential flow necessary to maintain a two water worlds scenario (i.e., physical separation between mobile and immobile water pools). We constructed 60 cm soil columns (20 cm-ID PVC) containing low soil structure (sieved soil material), subsoil structure (intact B horizon), and soil structure without matrix exchange (tubing reinforced macropores) to simulate multiple preferential flow scenarios. Columns were subjected to 3 rain storms of varying rainfall intensity (~2.5 cm h <sup>-1</sup>, ~5 cm h <sup>-1</sup>, and ~11 cm h <sup>-1</sup>) whose stable isotope signatures oscillated around known baseline values. Isotopic analysis was performed on collected leachate and matrix water sampled via direct vapor equilibration. Preliminary estimates of matrix water indicate up to 100% mixing with infiltrating rain water under low rainfall intensity (2.5 cm h <sup>-1</sup>) in subsoil structure columns, whereas high intensity rain (11 cm h<sup>-1</sup>) produced clear separation between columns with intact or artificial soil structure and those controlled for structure (low structure treatment). This separation was confirmed by preferential flow estimates; however minimizing matrix exchange (via artificial macropores) reduced preferential flow by a factor of 4 compared to soil with intact structure. These data suggest that distinct domain separation may only be possible under extreme precipitation intensity; and that exchange with less mobile storage in the soil matrix produces more preferential flow. We intend to use these estimates of preferential flow as a benchmark to understand the prevalence, persistence, and plausibility of ecohydrological separation. As a next step, we will use this conceptual framework to define how recurrent drought, elevated CO<sub>2</sub>, and warming may alter the partitioning of mobile and immobile water in mountain grasslands.</p>

scholarly journals Effects of preferential flow on snowmelt partitioning and groundwater recharge in frozen soils

2019 ◽  
Vol 23 (12) ◽  
pp. 5017-5031 ◽  
Author(s):  
Aaron A. Mohammed ◽  
Igor Pavlovskii ◽  
Edwin E. Cey ◽  
Masaki Hayashi
Keyword(s):  
Soil Moisture ◽  
Groundwater Recharge ◽  
Preferential Flow ◽  
Frozen Soil ◽  
Time Lags ◽  
Runoff Generation ◽  
Frozen Ground ◽  
Soil Matrix ◽  
Frozen Soils ◽  
Flow Through

Abstract. Snowmelt is a major source of groundwater recharge in cold regions. Throughout many landscapes snowmelt occurs when the ground is still frozen; thus frozen soil processes play an important role in snowmelt routing, and, by extension, the timing and magnitude of recharge. This study investigated the vadose zone dynamics governing snowmelt infiltration and groundwater recharge at three grassland sites in the Canadian Prairies over the winter and spring of 2017. The region is characterized by numerous topographic depressions where the ponding of snowmelt runoff results in focused infiltration and recharge. Water balance estimates showed infiltration was the dominant sink (35 %–85 %) of snowmelt under uplands (i.e. areas outside of depressions), even when the ground was frozen, with soil moisture responses indicating flow through the frozen layer. The refreezing of infiltrated meltwater during winter melt events enhanced runoff generation in subsequent melt events. At one site, time lags of up to 3 d between snow cover depletion on uplands and ponding in depressions demonstrated the role of a shallow subsurface transmission pathway or interflow through frozen soil in routing snowmelt from uplands to depressions. At all sites, depression-focused infiltration and recharge began before complete ground thaw and a significant portion (45 %–100 %) occurred while the ground was partially frozen. Relatively rapid infiltration rates and non-sequential soil moisture and groundwater responses, observed prior to ground thaw, indicated preferential flow through frozen soils. The preferential flow dynamics are attributed to macropore networks within the grassland soils, which allow infiltrated meltwater to bypass portions of the frozen soil matrix and facilitate both the lateral transport of meltwater between topographic positions and groundwater recharge through frozen ground. Both of these flow paths may facilitate preferential mass transport to groundwater.

scholarly journals Dye staining and excavation of a lateral preferential flow network

2009 ◽  
Vol 13 (6) ◽  
pp. 935-944 ◽  
Author(s):  
A. E. Anderson ◽  
M. Weiler ◽  
Y. Alila ◽  
R. O. Hudson
Keyword(s):  
Slope Stability ◽  
Solute Transport ◽  
Preferential Flow ◽  
Runoff Generation ◽  
Flow Paths ◽  
Soil Matrix ◽  
Preferential Flow Paths ◽  
Dye Staining ◽  
Hillslope Scale ◽  
Surrounding Soil

Abstract. Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m). We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.

Obvious and less obvious processes of aggregate formation in soil

2021 ◽  
Author(s):  
Hans-Jörg Vogel ◽  
Mar­ia Balseiro-Romero ◽  
Philippe C. Baveye ◽  
Alexandra Kravchenko ◽  
Wilfred Otten ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Structure ◽  
Solid Phase ◽  
Pore Space ◽  
Imaging Techniques ◽  
Mineral Soil ◽  
Aggregate Formation ◽  
Conceptual Approach ◽  
Soil Matrix ◽  
Biophysical Processes

<p>Soil structure, lately referred to as the ''architecture'' is a key to explain and understand all soil functions. The development of sophisticated imaging techniques over the last decades has led to significant progress in the description of this architecture and in particular of the geometry of the hierarchically-branched pore space in which transport of water, gases, solutes and particles occurs and where myriads of organisms live. Moreover, there are sophisticated tools available today to also visualize the spatial structure of the solid phase including mineral grains and organic matter. Hence, we do have access to virtually all components of soil architecture.</p><p>Unfortunately, it has so far proven very challenging to study the dynamics of soil architecture over time, which is of critical importance for soil as habitat and the turnover of organic matter. Several largely conflicting theories have been proposed to account for this dynamics, especially the formation of aggregates. We review these theories, and we propose a conceptual approach to reconcile them based on a consistent interpretation of experimental observations and by integrating known physical and biogeochemical processes. A key conclusion is that rather than concentrating on aggregate formation in the sense of how particles and organic matter reorganize to form aggregates as distinct functional units we should focus on biophysical processes that produce a porous, heterogeneous organo-mineral soil matrix that breaks into fragments of different size and stability when exposed to mechanical stress.  The unified vision we propose for soil architecture and the mechanisms that determine its temporal evolution, should pave the way towards a better understanding of soil processes and functions.</p>

The Daisy agroecological system model: A physically based model for preferential water flow and solute transport in drained agricultural fields

2021 ◽  
Author(s):  
Efstathios Diamantopoulos ◽  
Maja Holbak ◽  
Per Abrahamsen
Keyword(s):  
Solute Transport ◽  
Water Flow ◽  
Preferential Flow ◽  
Column Experiment ◽  
Soil Matrix ◽  
Physically Based Model ◽  
Physically Based ◽  
Rapid Transport ◽  
Preferential Water

<p>Preferential water flow and solute transport in agricultural systems affects not only the quality of groundwater but also the quality of surface waters like streams and lakes. This is due to the rapid transport of agrochemicals, immediately after application, through subsurface drainpipes and surface water. Experimental evidence attributes this to the occurrence of continuously connected pathways, connecting the soil surface directly with the drainpipes. We developed a physically-based model describing preferential flow and transport in biopores and implemented it in the agroecological model Daisy. The model simulates the often observed rapid transport of chemicals from   the upper soil layers to the drainpipes or to deeper layers of the soil matrix. Based on field investigations, biopores with specific characteristics can be parameterized as classes with different vertical and horizontal distributions. The model was tested against experimental data from a column experiment with an artificial biopore and showed good results in simulating preferential flow dynamics. We illustrate the performance of the new approach, by conducting five simulations assuming a two-dimensional simulation domain with different biopore parametrizations, from none to several different classes. The simulation results agreed with experimental observations reported in the literature, indicating rapid transport from the soil to the drainpipes. Furthermore, the different biopore parametrizations resulted in distinctly different leaching patterns, raising the expectation that biopore properties could be estimated or constrained based on observed leaching data and direct measurements.</p>

scholarly journals Soil Infrastructure, Interfaces & Translocation Processes in Inner Space ("Soil-it-is"): towards a road map for the constraints and crossroads of soil architecture and biophysical processes

2009 ◽  
Vol 13 (8) ◽  
pp. 1485-1502 ◽  
Author(s):  
L. W. de Jonge ◽  
P. Moldrup ◽  
P. Schjønning
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Structure ◽  
Energy Input ◽  
Pore Network ◽  
Health Economy ◽  
Matric Potential ◽  
Soil Matrix ◽  
Micro Scale ◽  
Road Map

Abstract. Soil functions and their impact on health, economy, and the environment are evident at the macro scale but determined at the micro scale, based on interactions between soil micro-architecture and the transport and transformation processes occurring in the soil infrastructure comprising pore and particle networks and at their interfaces. Soil structure formation and its resilience to disturbance are highly dynamic features affected by management (energy input), moisture (matric potential), and solids composition and complexation (organic matter and clay interactions). In this paper we review and put into perspective preliminary results of the newly started research program "Soil-it-is" on functional soil architecture. To identify and quantify biophysical constraints on soil structure changes and resilience, we claim that new approaches are needed to better interpret processes and parameters measured at the bulk soil scale and their links to the seemingly chaotic soil inner space behavior at the micro scale. As a first step, we revisit the soil matrix (solids phase) and pore system (water and air phases), constituting the complementary and interactive networks of soil infrastructure. For a field-pair with contrasting soil management, we suggest new ways of data analysis on measured soil-gas transport parameters at different moisture conditions to evaluate controls of soil matrix and pore network formation. Results imply that some soils form sponge-like pore networks (mostly healthy soils in terms of agricultural and environmental functions), while other soils form pipe-like structures (agriculturally poorly functioning soils), with the difference related to both complexation of organic matter and degradation of soil structure. The recently presented Dexter et al. (2008) threshold (ratio of clay to organic carbon of 10 kg kg−1) is found to be a promising constraint for a soil's ability to maintain or regenerate functional structure. Next, we show the Dexter et al. (2008) threshold may also apply to hydrological and physical-chemical interface phenomena including soil-water repellency and sorption of volatile organic vapors (gas-water-solids interfaces) as well as polycyclic aromatic hydrocarbons (water-solids interfaces). However, data for differently-managed soils imply that energy input, soil-moisture status, and vegetation (quality of eluded organic matter) may be equally important constraints together with the complexation and degradation of organic carbon in deciding functional soil architecture and interface processes. Finally, we envision a road map to soil inner space where we search for the main controls of particle and pore network changes and structure build-up and resilience at each crossroad of biophysical parameters, where, for example, complexation between organic matter and clay, and moisture-induced changes from hydrophilic to hydrophobic surface conditions can play a role. We hypothesize that each crossroad (e.g. between organic carbon/clay ratio and matric potential) may control how soil self-organization will manifest itself at a given time as affected by gradients in energy and moisture from soil use and climate. The road map may serve as inspiration for renewed and multi-disciplinary focus on functional soil architecture.

Dual permeability soil water dynamics and water uptake by roots in irrigated potato fields

Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
František Doležal ◽  
David Zumr ◽  
Josef Vacek ◽  
Josef Zavadil ◽  
Adriano Battilani ◽  
...  
Keyword(s):  
Soil Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Water Movement ◽  
Root Zone ◽  
Water Pressure ◽  
Boundary Curve ◽  
Water Dynamics ◽  
Permeability Model ◽  
Soil Matrix

AbstractWater movement and uptake by roots in a drip-irrigated potato field was studied by combining field experiments, outputs of numerical simulations and summary results of an EU project (www.fertorganic.org). Detailed measurements of soil suction and weather conditions in the Bohemo-Moravian highland made it possible to derive improved estimates of some parameters for the dual permeability model S1D_DUAL. A reasonably good agreement between the measured and the estimated soil hydraulic properties was obtained. The measured root zone depths were near to those obtained by inverse simulation with S1D _DUAL and to a boundary curve approximation. The measured and S1D _DUAL-simulated soil water pressure heads were comparable with those achieved by simulations with the Daisy model. During dry spells, the measured pressure heads tended to be higher than the simulated ones. In general, the former oscillated between the simulated values for soil matrix and those for the preferential flow (PF) domain. Irrigation facilitated deep seepage after rain events. We conclude that several parallel soil moisture sensors are needed for adequate irrigation control. The sensors cannot detect the time when the irrigation should be stopped.

Estimation of vineyard soil structure and preferential flow using dye tracer, X-ray tomography, and numerical simulations

Geoderma ◽  
2020 ◽  
Vol 380 ◽  
pp. 114699
Author(s):  
Vilim Filipović ◽  
Jasmina Defterdarović ◽  
Jiří Šimůnek ◽  
Lana Filipović ◽  
Gabrijel Ondrašek ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Soil Structure ◽  
Preferential Flow ◽  
X Ray ◽  
Dye Tracer ◽  
Vineyard Soil

Macropore-matrix mass transfer: reactive solute transport as quantified with Fluorescence imaging

2020 ◽  
Author(s):  
Christoph Haas ◽  
Ruth Ellerbrock ◽  
Horst H. Gerke
Keyword(s):  
Mass Transfer ◽  
Soil Properties ◽  
Fluorescence Imaging ◽  
Mass Exchange ◽  
Soil Structure ◽  
Transport Processes ◽  
Hydraulic Transport ◽  
Soil Matrix ◽  
Adsorption Sites ◽  
Sorption Characteristics

<p>Preferential flow paths in soils play a major role for transport processes of heat, gas, water, and solutes and are important adsorption sites. For mass-exchange processes and water storage in soils, small-scaled soil properties, like the spatial distribution of adsorption sites and their accessibility, and the permeability are crucial. Interfaces between macropores (i.e., earthworm burrows, cracks, and root channels) and the soil matrix control the mass exchange. Water and solute transfer through the interface between bio-pores, aggregate or crack surfaces and the matrix was traced at the scale of small soil blocks (≤45 mm edge length) with Fluorescein (i.e., a reactive, fluorescent dye). The objectives were to visualize and quantify hydraulic transport, and sorption characteristics of earthworm-, root- and shrinkage-induced interfaces. Batch experiments were performed to calibrate the Na-Fluorescein tracer concentration versus fluorescence-intensity relationship and to derive parameters for two kinetic sorption models (i.e., Freundlich vs. Langmuir). Fluorescence imaging in the laboratory of small soil blocks was applied with a self-constructed spraying device, and with the help of the calibration, small-scaled dye-concentration maps were derived. Time- and interface-dependent positions of the wetting fronts in vertical direction were estimated with the help of the cumulative infiltration. Assuming equilibrated conditions between Na-Fluorescein in solution (calculated by multiplying the locale dye-concentration and the local water content) and Na-Fluorescein sorbed to soil, the total mass transfers as a function of macropore-type and spraying time were determined. The results of the mass transfer for water and reactive solutes were characteristic for the soil structure type and depending on the composition of the macropore-matrix interface. Differences were explained by alterations in soil structure and chemical composition of the coatings. Results suggest relations between mass exchange and observable soil properties. This can be helpful for improving the numerical simulation of macropore-matrix mass transfer and inverse simulations of small-scaled hydraulic, transport, and sorption characteristics of macropore walls.</p>

Interrill erodibilities based on the rainfall intensity flow discharge erosivity factor

Soil Research ◽  
1993 ◽  
Vol 31 (3) ◽  
pp. 319 ◽  
Author(s):  
PIA Kinnell
Keyword(s):  
Rainfall Intensity ◽  
Soil Surface ◽  
Dynamic Factor ◽  
Experimental Conditions ◽  
Soil Matrix ◽  
Flow Discharge ◽  
Erosion Prediction ◽  
Water Erosion Prediction Project ◽  
Interrill Erosion ◽  
Erosion Environment

Interrill erodibilities are often determined using a model which considers the interrill erosion rate to vary directly with rainfall intensity (I) squared. However, it has been shown that the sediment discharge from an interrill area varies directly with I rather than I2 when factors such as flow discharge are also considered. Analysis of data from the experiments used to determine interrill erodibilities in the Water Erosion Prediction Project (WEPP) in terms of a model that uses both rainfall rate and flow discharge indicates that the susceptibilities of some soils to interrill erosion may differ considerably from the erodibilities determined from the WEPP model. Apart from the need to use models which better account for the variations in erosive stress, consideration has to be given to the fact that erodibility is a dynamic factor that can vary rapidly between two extremes. One of these extremes is associated with detachment-limiting conditions that may often be controlled by cohesion. The other extreme is associated with the complete protection of the soil matrix by a layer of pre-detached particles. When this extreme results, interrill erodibilities are controlled by the particle size and density characteristics of the pre-detached particles. Difficulties arise in extrapolating information from one scale to another, and from one soil where erodibility experiments have been performed to others where they have not because of the dynamic nature of the rain-flow-soil surface interaction. Also, the effect of slope gradient in the interrill erosion environment varies between soils and experimental conditions because of this interaction and the differing susceptibility of soils to rilling.

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