Planform and stratigraphic signature of proximal braided streams: remote-sensing and ground-penetrating-radar analysis of the Kicking Horse River, Canadian Rocky Mountains

2020 ◽  
Vol 90 (1) ◽  
pp. 131-149
Author(s):  
Natasha N. Cyples ◽  
Alessandro Ielpi ◽  
Randy W. Dirszowsky

ABSTRACT Braided rivers have accumulated a dominant fraction of the terrestrial sedimentary record, and yet their morphodynamics in proximal intermountain reaches are still not fully documented—a shortcoming that hampers a full understanding of sediment fluxes and stratigraphic preservation in proximal-basin tracts. Located in the eastern Canadian Cordillera near the continental divide, the Kicking Horse River is an iconic stream that has served as a model for proximal-braided rivers since the 1970s. Legacy work on the river was based solely on ground observations of small, in-channel bars; here we integrate field data at the scale of individual bars to the entire channel belt with time-lapse remote sensing and ground-penetrating-radar (GPR) imaging, in order to produce a more sophisticated morphodynamic model for the river. Cyclical discharge fluctuations related to both diurnal and seasonal variations in melt-water influx control the planform evolution and corresponding stratigraphic signature of trunk channels, intermittently active anabranch channels, and both bank-attached and mid-channel bars. Three-dimensional GPR fence diagrams of compound-bar complexes are built based on the identification of distinct radar facies related to: i) accretion and migration of unit bars, ii) both downstream and lateral outbuilding of bar-slip foresets; iii) buildup of bedload sheets, iv) channel avulsion, and v) accretion of mounded bars around logs or outsized clasts. Trends observed downstream-ward include decreases in gradient and grain size decreases, trunk-channel shrinkage, intensified avulsion (with increase in abundance for anabranch channels), and a shift from high-relief to low-relief bar topography. The integration of ground sedimentology, time-lapse remote sensing, and GPR imaging demonstrates that proximal-braided streams such as the Kicking Horse River can be critically compared to larger systems located farther away from their source uplands despite obvious scale differences.

Author(s):  
Simone Di Prima ◽  
Thierry Winiarski ◽  
Rafael Angulo-Jaramillo ◽  
Ryan D. Stewart ◽  
Mirko Castellini ◽  
...  

<p>Preferential flow is more the rule than the exception, in particular during water infiltration experiments. In this study, we demonstrate the potential of GPR monitoring to detect preferential flows during water infiltration. We monitored time-lapse ground penetrating radar (GPR) surveys in the vicinity of single-ring infiltration experiments and created a three-dimensional (3D) representation of infiltrated water below the devices. For that purpose, radargrams were constructed from GPR transects conducted over two grids (1 m × 1 m) before and after the infiltration tests. The obtained signal was represented in 3D and a threshold was chosen to part the domain into wetted and non-wetted zones, allowing the determination of the infiltration bulb. That methodology was used to detect the infiltration below the devices and clearly pointed at nonuniform flows in correspondence with the heterogeneous soil structures. The protocol presented in this study represents a practical and valuable tool for detecting preferential flows at the scale of a single ring infiltration experiment.</p>


2021 ◽  
Vol 13 (4) ◽  
pp. 560
Author(s):  
Xianguo Zhang ◽  
Chengyan Lin ◽  
Tao Zhang ◽  
Daowu Huang ◽  
Derong Huang ◽  
...  

Bar top hollows (BTHs) are morphological elements recognized in modern braided rivers; however, information regarding their depositional features and types of filling units in ancient strata is unclear. This is an important reason behind why it is difficult to identify BTH units in subsurface reservoirs. A Middle Jurassic dryland sandy braided river outcrop in northwestern China is characterized in this study through the application of an unmanned aerial vehicle (UAV) surveying and mapping, and ground penetrating radar (GPR). A workflow of UAV data processing has been established, and a 3D digital outcrop model has been built. By observation and measurement of the outcrop model and GPR profiles, two types of BTH filled units were found: (a) sandstone-filled, and (b) mudstone-filled hollows. Both of these units were located between two adjacent bar units in an area that is limited to a compound bar, and were developed in the upper part of a braided bar depositional sequence. The ellipse-shaped, sandstone-filled unit measures 10 m × 27 m in map view and reaches a maximum thickness of 5 m. The transversal cross-section across the BTHs displays a concave upward basal surface, while the angle of the inclined structures infilling the BTHs decreases up-section. The GPR data show that, in the longitudinal profile, the basal surface is relatively flat, and low-angle, inclined layers can be observed in the lower- and middle part of the sandstone-filled BTHs. In contrast, no obvious depositional structures were observed in the mudstone-filled BTH in outcrop. The new understanding of BTH has a wide application, including the optimization of CO2 storage sites, fresh water aquifers exploration, and oil and gas reservoir characterization.


2015 ◽  
Vol 19 (3) ◽  
pp. 1125-1139 ◽  
Author(s):  
P. Klenk ◽  
S. Jaumann ◽  
K. Roth

Abstract. High-resolution time-lapse ground-penetrating radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments that have been carried out at our artificial ASSESS test site and observed with surface-based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows the study of soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the feasibility of monitoring the dynamic shape of the capillary fringe reflection and (ii) the relative precision of monitoring soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.


2020 ◽  
Vol 726 ◽  
pp. 138511 ◽  
Author(s):  
Simone Di Prima ◽  
Thierry Winiarski ◽  
Rafael Angulo-Jaramillo ◽  
Ryan D. Stewart ◽  
Mirko Castellini ◽  
...  

Radio Science ◽  
2019 ◽  
Vol 54 (8) ◽  
pp. 728-737 ◽  
Author(s):  
Wenji Zhang ◽  
Ahmad Hoorfar ◽  
Qiang An

The Holocene ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 820-833 ◽  
Author(s):  
Erica Corradini ◽  
Dennis Wilken ◽  
Marco Zanon ◽  
Daniel Groß ◽  
Harald Lübke ◽  
...  

We investigate the landscape development of the early Mesolithic hunter-gatherer sites of Duvensee (10000–6500 cal. BCE). Based on ground-penetrating radar (GPR) and geoarchaeological drillings, we present for the first time a three-dimensional (3D) reconstruction of the palaeoenvironment of 63 ha covering subarea of the former lake during the Mesolithic. The archaeological aims were (1) to detect the location of former islands possibly hosting hunter-gatherer settlements and (2) to reconstruct the ancient landscape development for understanding prehistoric land use. The research in Duvensee lasts almost 100 years, providing vivid illustrations of early Mesolithic life. Clusters of Mesolithic camps have been found located on small sand hills that formed islands in the prehistoric lake. For this environment, we present depth maps of the three most important sedimentary facies interfaces of the ancient Lake Duvensee. Interface1 represents the transition between coarse organic sediments (peat and coarse detritus gyttja) and fine-grained organic sediments (fine detritus gyttja, calcareous gyttja), Interface2 represents the transition to the underlying clayish-loamy sediments, and Interface3 marks the top of the basal sand deposits at the lake bottom. From Interface3, we identified the location and extent of five former islands with Mesolithic camps. Stratigraphic information from the corings enabled us to create a 3D model of the spatio-temporal development of the Duvensee bog. The locations of the islands and their estimated dive-up times agree with the spatio-temporal pattern of the previous archaeological finds. The model shows where hunter-gatherers could settle and move from one island to another following the shorelines of the overgrowing lake. The 3D stratigraphic model provides growth and shrinking rates of the island and lake areas in the Mesolithic, and volumes of organic and non-organic deposited lake sediments. Besides, it provides a basis for a sustainable groundwater management needed for heritage preservation.


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