scholarly journals Impacts of a capillary barrier on infiltration and subsurface stormflow in layered slope deposits monitored with 3-D ERT and hydrometric measurements

2017 ◽  
Vol 21 (10) ◽  
pp. 5181-5199 ◽  
Author(s):  
Rico Hübner ◽  
Thomas Günther ◽  
Katja Heller ◽  
Ursula Noell ◽  
Arno Kleber

Abstract. Identifying principles of water movement in the shallow subsurface is crucial for adequate process-based hydrological models. Hillslopes are the essential interface for water movement in catchments. The shallow subsurface on slopes typically consists of different layers with varying characteristics. The aim of this study was to draw conclusions about the infiltration behaviour, to identify water flow pathways and derive some general interpretations for the validity of the water movement on a hillslope with periglacial slope deposits (cover beds), where the layers differ in their sedimentological and hydrological properties. Especially the described varying influence of the basal layer (LB) as an impeding layer on the one hand and as a remarkable pathway for rapid subsurface stormflow on the other. We used a time lapse 3-D electrical resistivity tomography (ERT) approach combined with punctual hydrometric data to trace the spreading and the progression of an irrigation plume in layered slope deposits during two irrigation experiments. This multi-technical approach enables us to connect the high spatial resolution of the 3-D ERT with the high temporal resolution of the hydrometric devices. Infiltration through the uppermost layer was dominated by preferential flow, whereas the water flow in the deeper layers was mainly matrix flow. Subsurface stormflow due to impeding characteristic of the underlying layer occurs in form of organic layer interflow and at the interface to the first basal layer (LB1). However, the main driving factor for subsurface stormflow is the formation of a capillary barrier at the interface to the second basal layer (LB2). The capillary barrier prevents water from entering the deeper layer under unsaturated conditions and diverts the seepage water according to the slope inclination. With higher saturation, the capillary barrier breaks down and water reaches the highly conductive deeper layer. This highlights the importance of the capillary barrier effect for the prevention or activation of different flow pathways under variable hydrological conditions.

2017 ◽  
Author(s):  
Rico Hübner ◽  
Thomas Günther ◽  
Katja Heller ◽  
Ursula Noell ◽  
Arno Kleber

Abstract. Identifying principles of water movement in the shallow subsurface is crucial for adequate process-based hydrological models. Hillslopes are the essential interface for water movement in catchments. The shallow subsurface on slopes typically consist of different layers with varying characteristics. The aim of this study was to draw conclusion about the infiltration behaviour, to identify water flow pathways and derive general validity about the water movement on a hillslope with periglacial slope deposits (cover beds), where the layers differ in their sedimentological and hydrological properties. Especially the described varying influence of the basal layer (LB) as impeding layer on the one hand and as a remarkable pathway for rapid subsurface stormflow on the other. We used a time lapse 3D ERT approach combined with punctual hydrometric data to trace the spreading and the progression of an irrigation plume in layered slope deposits during two irrigation experiments. This multi-technical approach enables us to connect the high spatial resolution of the 3D ERT with the high temporal resolution of the hydrometric devices. Infiltration through the uppermost layer was dominated by preferential flow, whereas the water flow in the deeper layers was mainly matrix flow. Subsurface stormflow due to impeding characteristic of the underlying layer occurs in form of "organic layer interflow" and at the interface to the first basal layer (LB1). However, the main driving factor for subsurface stormflow is the formation of a capillary barrier at the interface to the second basal layer (LB2). The capillary barrier prevents water from entering the deeper layer under unsaturated conditions and diverts the seepage water according to the slope inclination. With higher saturation the capillary barrier breaks down and water reaches the highly conductive deeper layer. This highlights the importance of the capillary barrier effect for the prevention or activation of different flow pathways under variable hydrological conditions.


2014 ◽  
Vol 11 (6) ◽  
pp. 5859-5903 ◽  
Author(s):  
R. Hübner ◽  
K. Heller ◽  
T. Günther ◽  
A. Kleber

Abstract. Hillslopes are one of the basic units that mainly control water movement and flow pathways within catchments. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap of knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. To improve the knowledge of hydrological responses on hillslopes with periglacial cover beds, hydrometrical measurements have been carried out on a small spring catchment in the eastern Ore Mountains since November 2007. In addition, surface ERT measurements of several profiles were applied to enhance resolution of punctual hydrometric data. From May to December 2008 geoelectrical monitoring in nearly weekly intervals was implemented to trace seasonal moisture dynamics on the hillslope scale. To obtain the link between water content and resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data and resulting in remarkable coincidence. The measured resistivity shows a close correlation with precipitation. Depending on the amount and intensity of rain, different depths were affected by seepage water. Three different types of response to different amounts of precipitation (small, medium, high), could be differentiated. A period with a small amount causes a short interruption of the drying pattern at the surface in summer, whereas a medium amount induces a distinctive reaction at shallow depth (<0.9 m), and a high amount results in a strong response reaching down to 2 m.


Géotechnique ◽  
2021 ◽  
pp. 1-25
Author(s):  
Liang-Tong Zhan ◽  
Guang-Yao Li ◽  
Bate Bate ◽  
Yun-Min Chen

Capillary barrier effect (CBE) is employed in a large number of geotechnical applications to decrease deep percolation or increase slope stability. However, the micro-scale behaviour of CBE is rarely investigated, and thus hampers the scientific design of capillary barrier systems. This study uses microfluidics to explore the micro-scale behaviour of CBE. Capillarity-driven water flow processes from fine to coarse porous media with different pore topologies and sizes were performed and analysed. The experimental results demonstrate that the basic physics of CBE is the preferential water movement into the fine porous media due to the larger capillarity. The effects of CBE on water flow processes can be identified as delaying the occurrence of breakthrough into the coarse porous media and increasing the water storage of the fine porous media. The CBE can impede the increase of the normalized length and decrease the normalized width of the water front, suggesting that the two normalized parameters are potential indicators to assess the performance of CBE at micro scale. CBE can be formed in square and honeycomb networks with the ratio of coarse to fine pore throat width larger than 2.0 when gravity is neglected, and its performance can be affected by pore topology and size.


2013 ◽  
Vol 10 (6) ◽  
pp. 8233-8277 ◽  
Author(s):  
P. Schneider ◽  
L. Strouhal ◽  
S. Pool ◽  
J. Seibert

Abstract. This study investigated runoff formation processes of a pre-alpine hillslope prone to slide. The experimental pasture plot (40 m × 60 m) is located in the northern front range of the Swiss Alps on a 30° steep hillslope (1180 m a.s.l., 1500+ mm annual precipitation). A gleysol (H-Go-Gr) overlies weathered marlstone and conglomerate of subalpine molasse. We conducted sprinkling experiments on a subplot (10 m × 10 m) with variable rainfall intensities. During both experiments fluorescein line-tracer injections into the topsoil, and sodium chloride (NaCl) injections into the sprinkling water were used to monitor flow velocities in the soil. The observed flow velocities for fluorescein in the soil were 1.2 and 1.4 × 10−3 m s−1. The NaCl breakthrough occurred almost simultaneously in all monitored discharge levels (0.05, 0.25 and 1 m depth), indicating a high infiltration capacity and efficient drainage of the soil. These initial observations suggested "transmissivity feedback", a form of subsurface stormflow, as the dominant runoff process. However, the results of a brilliant blue dye tracer experiment completely changed our perceptions of the hillslope's hydrological processes. Excavation of the dye-stained soils highlighted the dominance of "organic layer interflow", a form of shallow subsurface stormflow. The dye stained the entire H horizon, vertical soil fractures, and macropores (mostly worm burrows) up to 50 cm depth. Lateral drainage in the subsoil or at the soil–bedrock interface was not observed, and thus was limited to the organic topsoil. In the context of shallow landslides, the subsoil (Go/Gr) acted as an infiltration and exfiltration barrier, which produced significant lateral saturated drainage in the topsoil (H) and possibly a confined aquifer in the bedrock.


2014 ◽  
Vol 955-959 ◽  
pp. 3640-3644
Author(s):  
He Xiang Zheng ◽  
Xue Song Cao ◽  
Jia Bin Wu ◽  
Jian Cheng Zhang

Land roughness is an important parameter of border irrigation in the surface water flow movement, it affects of the water movement process and affects irrigation efficiency, so it’s necessary combined with field surface other parameters to study irrigation field roughness to the irrigation efficiency. Agreement is good between simulated by SIRMOD model and measured values​​ through field trials the measured data of water flow advance and regression process, and indicating with SIRMOD model can simulate border irrigation process. Four kinds of typical field surface roughness of irrigation simulation by SIRMOD model and analysis of the results obtained: land roughness difference of water flow advance and regression process influence significantly, the water flow advance and regression process is better with the small land roughness, and the curve of water flow advance and regression becomes uneven, so irrigation efficiency significant reduction with the field surface roughness increases.


2000 ◽  
Vol 57 (S2) ◽  
pp. 60-72 ◽  
Author(s):  
J E Evans ◽  
E E Prepas ◽  
K J Devito ◽  
B G Kotak

Phosphorus dynamics in shallow subsurface waters (<2.5 m depth) were studied in harvested and unharvested subcatchments of a Boreal Plain lake. The organic soil layer was underlain by discontinuous layers of sand and clay glacial till. Total dissolved P (TDP) concentrations (6-798 µg·L-1) of discrete water samples from mineral layers (0.9-2.5 m deep) generally decreased with depth, were negatively related to Ca (rs < -0.7), and were lower in clay. When the groundwater table rose and saturated the organic layer, TDP concentrations increased in the composite (organic mineral layer) but not in the discrete (mineral layer) water samples, indicating that elevated TDP concentrations originate from the near-surface organic layer. TDP concentrations in composite samples were negatively correlated with water table depth (rs = -0.6) and were positively correlated with transmissivity (rs = 0.7) and dissolved organic C concentration (rs > 0.6). In the riparian buffer zone of the harvested subcatchment, TDP concentrations of composite samples decreased during high runoff, but these values remained higher than concentrations in the unharvested subcatchment. However, surface topography and variable depth to confining clay layers resulted in higher groundwater tables in the harvested subcatchment, especially in the cut area. Mean daily TDP export coefficients were similar between the unharvested (14 µg·m-2) and harvested (12 µg·m-2) subcatchments.


2014 ◽  
Vol 56 (3) ◽  
pp. 520-531 ◽  
Author(s):  
Joonghyuk Park ◽  
Hae Koo Kim ◽  
Jeongeun Ryu ◽  
Sungsook Ahn ◽  
Sang Joon Lee ◽  
...  
Keyword(s):  

1975 ◽  
Vol 55 (4) ◽  
pp. 941-948 ◽  
Author(s):  
P. A. DUBÉ ◽  
K. R. STEVENSON ◽  
G. W. THURTELL ◽  
H. H. NEUMANN

Determinations of plant resistance to water flow from measurements of leaf water potential at steady transpiration rates were made on different lines of corn (Zea mays L.). Two inbreds, Q188, a wilting mutant, and DR1, an inbred line shown to have at least some heat and drought tolerance under field conditions, were compared to a commercial single-cross hybrid, United 106. The purpose of the experiment was to isolate the cause of the wilting characteristic of Q188. A linear relationship was found between leaf water potential and transpiration rate for all lines. No water potential gradients were found at zero transpiration. Low total plant resistances were observed in United 106 and DR1, with the major resistance being in the root system in both genotypes. Although the resistance to water movement through the roots and lower stalk in Q188 did not appear to differ from those of the other lines, a much larger resistance was found in the upper stalk of Q188; resistance to water movement through the lower stalk (up to node 5) decreased as the plants matured from 55 to 70 days of age but no comparable changes occurred in the upper portions of the stem. In vivo detection of the xylem vessels with staining techniques confirmed the observed differences in resistances.


2018 ◽  
Vol 89 (8) ◽  
pp. 1455-1471 ◽  
Author(s):  
Shuaitong Liang ◽  
Ning Pan ◽  
Yuexin Cui ◽  
Xiongying Wu ◽  
Xuemei Ding

This study is about the heat and mass transport phenomena in a system with steam jet flow to eliminate/alleviate cloth wrinkles. We first adopted a theoretical approach to derive the mean capillary radii so that a fabric can be characterized as an assembly of capillary tubes with varying diameters. We then analyzed the processes as a heat transfer via the fibers and water via the pores in fabrics of different anisotropies. During water movement, the water weight actually intensifies the inherent anisotropy of the fabric in the water flow pattern. For heat transfer, the water weight becomes irrelevant and both convection and radiation are shown to be too trivial to include. Corresponding experiments are also conducted, using infrared and visible light cameras to record the heat and water flow processes, respectively. The results are compared with the theoretical predictions and the discrepancies are explored and explained.


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