Vadose Zone Characterisation for Hydrogeological and Geotechnical Applications

Dippenaar, Matthys Alois; Rooy, J.L. Van

doi:10.1007/978-3-319-93127-2_10

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…(ii) at medium flow rates, rivulets form and only snap at the fracture's end; and (iii) at high flow rates, rivulets that form are maintained throughout the fracture. These findings were confirmed by Brouwers and Dippenaar (2018) during their experiments investigating flow mechanisms at the soil-rock interface, as well as by Dippenaar and Van Rooy (2019) and Jones et al (2019) based on partially saturated fracture flow experiments.…”

Section: Introductionmentioning

confidence: 52%

Lugeon Tests at Partial Saturation: Experimental and Empirical Contributions

2018

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Implications of improved understanding of variably saturated flow are numerous, especially given the complexity, heterogeneity and anisotropy of the intermediate fractured vadose zone. One such an implication is the quantification of water movement for engineering purposes, as flow through unsaturated discontinuities cannot be quantified through commonly applied saturated approaches. This paper presents an experimental study using geotechnical centrifuge modelling to investigate flow behaviour during Lugeon tests, through the fundamental concept of a smooth, clean, open fracture, at partial saturation. The study comprised flow visualisation experiments conducted on transparent replicas of horizontal and inclined fractures, with water injected under a consecutive series of ascending and descending pressures. Findings from the research proved that preferential flow occupied the minority of cross-sectional area despite the hydraulic pressure. Furthermore, the observed behaviour of these preferential pathways indicated non-linear flow. Deviation from linearity occurred at small fluxes and is likely as a result of inertial effects due to fluid bending at the inlet source into the fracture. In order to assess these non-linear results, the Forchheimer relationship was used to predict the flow rate at the imposed hydraulic heads. As the width of the fracture could not be used as input into the equation, due to the lack of saturation across its width, the width of the flow path was used instead. This resulted in the predicted results comparing well with the measured flow rates, and indicates that the Forchheimer relationship can potentially be used to describe unsaturated flow in discrete, open fractures.

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Section: Introductionmentioning

confidence: 52%

Lugeon Tests at Partial Saturation: Experimental and Empirical Contributions

2018

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“…Data obtained from the Fullscale Model shows that this angle exists somewhere between 2.5° and 5° or greater, as the sharpest increases in the discharges, regardless of material selection, were measured from points Q2 to Q4 and especially in runoff (Q5) between these angles. A possible reason for this behaviour may be the occurrence of capillary barred perching between the SC and the remainder of the layer works at low inclines (Dippenaar and van Rooy, 2019), as the SC generally has a higher density and thus lower permeability than the lower layers of the pavement. In addition, the interface between the SC and lower layers may also simulate the bottom of a horizontal fracture, where lateral flow presents a longer pathways and higher energy requirements (Jones et al, 2018).…”

Section: The Effect Of Inclinementioning

confidence: 99%

“…When incline is increased, the boundary between the SC and the rest of the layer works is no longer horizontal. This results in the migration of water along the boundary by percolation, to areas of the SC with a lower saturation through cohesion and gravity, rather than water crossing the boundary which requires more energy (Dippenaar and van Rooy, 2019).…”

Section: The Effect Of Inclinementioning

confidence: 99%

Seepage Through Permeable Interlocking Concrete Pavements and Their Subgrades Using a Large Infiltration Table Apparatus

Vuuren

Dippenaar

Biljon³

et al. 2021

Int. J. Pavement Res. Technol.

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Permeable Interlocking Concrete Pavements (PICP) are being used increasingly in stormwater management. A two-year experimental study was conducted to quantify some uncertain parameters related to PICP. The study entailed the hydraulic testing of a representative volume of PICP within a specially constructed Infiltration TableApparatus with a surface area of 10 m 2 , and able to be tilted up to 6°. The study aimed to address some of the controls of infiltration into, and flow through PICP by investigating the effect of the selected construction materials and the incline of the pavements. Based on the permeability data gained on PICP, it was verified that both the choice of construction materials (in both the layer works and the sand used for fill between the bricks) and the incline of the pavements were found to affect their hydraulic properties. In general, the selection of lower permeability materials in a PICP surface layer, and/ or increasing the incline, decrease the overall permeability of the pavement.

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“…For example, the generation mechanisms, magnitude, and timing of streamflow could be altered by infrastructure [2][3][4]. On the other hand, these changes in hydrological processes can lead to infrastructural damages when they exceed construction thresholds [5,6]. Lately, the focus in urban development has been on water-sensitive design strategies, which not only aim to protect infrastructure from water damage, but also limit the occurrence of flood events, while striving to maintain pre-development hydrological dynamics [7].…”

Section: Introductionmentioning

confidence: 99%

Combining Historical Remote Sensing, Digital Soil Mapping and Hydrological Modelling to Produce Solutions for Infrastructure Damage in Cosmo City, South Africa

Zijl

Tol

Bouwer³

et al. 2020

Remote Sensing

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Urbanization and hydrology have an interactive relationship, as urbanization changing the hydrology of a system and the hydrology commonly causing structural damage to the infrastructure. Hydrological modelling has been used to quantify the water causing structural impacts, and to provide solutions to the issues. However, in already-urbanized areas, creating a soil map to use as input in the modelling process is difficult, as observation positions are limited and visuals of the natural vegetation which indicate soil distribution are unnatural. This project used historical satellite images in combination with terrain parameters and digital soil mapping methods to produce an accurate (Kappa statistic = 0.81) hydropedology soil map for the Cosmo City suburb in Johannesburg, South Africa. The map was used as input into the HYDRUS 2D and SWAT hydrological models to quantify the water creating road damage at Kampala Crescent, a road within Cosmo City (using HYDRUS 2D), as well as the impact of urbanization on the hydrology of the area (using SWAT). HYDRUS 2D modelling showed that a subsurface drain installed at Kampala Crescent would need a carrying capacity of 0.3 m3·h−1·m−1 to alleviate the road damage, while SWAT modelling shows that surface runoff in Cosmo City will commence with as little rainfall as 2 mm·month−1. This project showcases the value of multidisciplinary work. The remote sensing was invaluable to the mapping, which informed the hydrological modelling and subsequently provided answers to the engineers, who could then mitigate the hydrology-related issues within Cosmo City.

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Vadose Zone Characterisation for Hydrogeological and Geotechnical Applications

Cited by 4 publications

References 13 publications

Lugeon Tests at Partial Saturation: Experimental and Empirical Contributions

Lugeon Tests at Partial Saturation: Experimental and Empirical Contributions

Seepage Through Permeable Interlocking Concrete Pavements and Their Subgrades Using a Large Infiltration Table Apparatus

Combining Historical Remote Sensing, Digital Soil Mapping and Hydrological Modelling to Produce Solutions for Infrastructure Damage in Cosmo City, South Africa

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