scholarly journals Mapping Paleohydrology of the Ephemeral Kuiseb River, Namibia, from Radar Remote Sensing

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1441
Author(s):  
Philippe Paillou ◽  
Sylvia Lopez ◽  
Eugene Marais ◽  
Klaus Scipal
Keyword(s):  
High Resolution ◽  
Drainage System ◽  
Climatic Conditions ◽  
Radar Images ◽  
The North ◽  
Digital Elevation ◽  
Ephemeral Rivers ◽  
High Resolution Radar ◽  
Northern Edge ◽  
Ground Penetrating

The Kuiseb River is one of the major ephemeral rivers of Western Namibia, setting the northern limit of the Namib Sand Sea and outflowing in the Atlantic Ocean at Walvis Bay. Such ephemeral rivers are of the highest importance for the country since they are related both to recent past climatic conditions and to potential water resources. Using high-resolution radar images from the Japanese ALOS-2 satellite, we mapped for the first time the numerous channels hidden under the surface aeolian sediments: while the non-permanent tributaries of the Kuiseb River appear north of its present-day bed, a wide paleochannel system running westward, assumed by previous studies, could be clearly observed in the interdune valleys in the south. Radar-detected channels were studied during fieldwork in May 2019, which produced both subsurface ground-penetrating radar profiles and high-resolution drone-generated digital elevation models. It allowed us to confirm the existence of the “Paleo–Kuiseb” drainage system, a remnant of the Holocene history of the Kuiseb River, moving northward under the progression of the Namib Sand Sea. Our observations also contribute to the explanation of the young age of the linear dunes at the northern edge of the Namib Sand Sea, which are currently active and are pushing the Kuiseb River course toward the north.

scholarly journals Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar

2011 ◽  
Vol 5 (1) ◽  
pp. 139-149 ◽  
Author(s):  
K. Bælum ◽  
D. I. Benn
Keyword(s):  
Ground Penetrating Radar ◽  
Thermal Structure ◽  
Drainage System ◽  
High Arctic ◽  
Differential Gps ◽  
Glacier Surface ◽  
Digital Elevation ◽  
Drainage Channels ◽  
Ground Penetrating ◽  
Subglacial Drainage

Abstract. Proglacial icings accumulate in front of many High Arctic glaciers during the winter months, as water escapes from englacial or subglacial storage. Such icings have been interpreted as evidence for warm-based subglacial conditions, but several are now known to occur in front of cold-based glaciers. In this study, we investigate the drainage system of Tellbreen, a 3.5 km long glacier in central Spitsbergen, where a large proglacial icing develops each winter, to determine the location and geometry of storage elements. Digital elevation models (DEMs) of the glacier surface and bed were constructed using maps, differential GPS and ground penetrating radar (GPR). Rates of surface lowering indicate that the glacier has a long-term mass balance of −0.6 ± 0.2 m/year. Englacial and subglacial drainage channels were mapped using GPR, showing that Tellbreen has a diverse drainage system that is capable of storing, transporting and releasing water year round. In the upper part of the glacier, drainage is mainly via supraglacial channels. These transition downglacier into shallow englacial "cut and closure" channels, formed by the incision and roof closure of supraglacial channels. Below thin ice near the terminus, these channels reach the bed and contain stored water throughout the winter months. Even though no signs of temperate ice were detected and the bed is below pressure-melting point, Tellbreen has a surface-fed, channelized subglacial drainage system, which allows significant storage and delayed discharge.

Ground‐penetrating radar surveys used in archaeological investigations

Geophysics ◽  
1986 ◽  
Vol 51 (3) ◽  
pp. 595-604 ◽  
Author(s):  
C. J. Vaughan
Keyword(s):  
Sixteenth Century ◽  
High Resolution ◽  
Impact Assessment ◽  
Ground Penetrating Radar ◽  
National Museum ◽  
Assessment Program ◽  
Reconnaissance Survey ◽  
Ongoing Work ◽  
High Resolution Radar ◽  
Ground Penetrating

During 1982 and 1983, two ground‐penetrating radar surveys were carried out in conjunction with archaeological investigations in Canada. The first survey was a detailed, high‐resolution radar survey at the site of a sixteenth century Basque whaling station on the Labrador coast designed to locate the graves of the Basques. The second was a rapid, low‐resolution reconnaissance survey as part of a prehistory impact assessment program at the site of the new National Museum of Man in Hull, Quebec. Both surveys were experimental and were designed to see whether ground‐penetrating radar would be useful for identifying and locating anomalies of archeological significance. Radar was successful in detecting archeological anomalies several meters in size at both locations, and the high‐resolution survey was moderately successful in identifying Basque graves. Ongoing work involves comparing radar results with the archaeological investigations to increase the understanding of how radar can be applied to archaeology and to improve interpretation of radar responses to artifacts.

scholarly journals Reliable Orientation Estimation of Vehicles in High-Resolution Radar Images

2016 ◽  
Vol 64 (9) ◽  
pp. 2986-2993 ◽  
Author(s):  
Fabian Roos ◽  
Dominik Kellner ◽  
Jurgen Dickmann ◽  
Christian Waldschmidt
Keyword(s):  
High Resolution ◽  
Orientation Estimation ◽  
Radar Images ◽  
High Resolution Radar

scholarly journals Ice shelf basal melt rates from a high-resolution digital elevation model (DEM) record for Pine Island Glacier, Antarctica

2019 ◽  
Vol 13 (10) ◽  
pp. 2633-2656 ◽  
Author(s):  
David E. Shean ◽  
Ian R. Joughin ◽  
Pierre Dutrieux ◽  
Benjamin E. Smith ◽  
Etienne Berthier
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
Heat Content ◽  
Elevation Change ◽  
Ice Shelf ◽  
Amundsen Sea ◽  
The North ◽  
Digital Elevation ◽  
Grounding Line ◽  
Basal Melting

Abstract. Ocean-induced basal melting is responsible for much of the Amundsen Sea Embayment ice loss in recent decades, but the total magnitude and spatiotemporal evolution of this melt is poorly constrained. To address this problem, we generated a record of high-resolution digital elevation models (DEMs) for Pine Island Glacier (PIG) using commercial sub-meter satellite stereo imagery and integrated additional 2002–2015 DEM and altimetry data. We implemented a Lagrangian elevation change (Dh∕Dt) framework to estimate ice shelf basal melt rates at 32–256 m resolution. We describe this methodology and consider basal melt rates and elevation change over the PIG ice shelf and lower catchment from 2008 to 2015. We document the evolution of Eulerian elevation change (dh∕dt) and upstream propagation of thinning signals following the end of rapid grounding line retreat around 2010. Mean full-shelf basal melt rates for the 2008–2015 period were ∼82–93 Gt yr−1, with ∼200–250 m yr−1 basal melt rates within large channels near the grounding line, ∼10–30 m yr−1 over the main shelf, and ∼0–10 m yr−1 over the North shelf and South shelf, with the notable exception of a small area with rates of ∼50–100 m yr−1 near the grounding line of a fast-flowing tributary on the South shelf. The observed basal melt rates show excellent agreement with, and provide context for, in situ basal melt-rate observations. We also document the relative melt rates for kilometer-scale basal channels and keels at different locations on the ice shelf and consider implications for ocean circulation and heat content. These methods and results offer new indirect observations of ice–ocean interaction and constraints on the processes driving sub-shelf melting beneath vulnerable ice shelves in West Antarctica.

GIS based morphostratigraphic evaluation of glaciofluvial terraces in the foreland of the European Alps

2020 ◽  
Author(s):  
Thomas Pollhammer ◽  
Bernhard Salcher ◽  
Florian Kober ◽  
Gaudenz Deplazes
Keyword(s):  
High Resolution ◽  
Digital Elevation Models ◽  
Regional Scale ◽  
European Alps ◽  
Rhine River ◽  
Geological Evidence ◽  
The North ◽  
Digital Elevation ◽  
Stratigraphic Model ◽  
Alpine Foreland

<p>Glacial and glaciofluvial sediments of the North Alpine Foreland have been subject to extensive quaternary research for more than a century. Nevertheless, a regional scale stratigraphic model has not been proposed since Penk & Brückner (1909). Since then, geological evidence were fit into local stratigraphic classifications, leading to severe inconsistencies across different countries/regions. The following study aims to solve inconsistencies by a morphostratigraphical approach, applying innovative methods utilizing new high-resolution digital elevation models, existing geodata and information from literature.</p><p>First, the abundant information from literature was reviewed to create a synopsis of commonly used terrace stratigraphic classifications. Second, geologic maps and (high-resolution) digital elevation models were compiled in a GIS database. To process this data, a new toolset was developed (using software R), fitting the requirements of morphostratigraphic analyses. These mainly involve the processing and statistic evaluation of terrace-top surfaces. Based on these analyses, we discussed fluvial, glacial and geodynamic factors, controlling the observed hypsometric parameters (concavity, slope, relative heights). To stratigraphically compare results across catchments and regions, the modern Danube and Rhine River were used as “fixed” base-levels to which tributary terrace tops were extrapolated. Terrace elevations above these base-levels were used as proxy to evaluate the rare absolute and otherwise inferred terrace ages from literature. Derived morphostratigraphic evidence provides an objective basis to discuss and harmonise the highly complex and diverging stratigraphic classification schemes across North Alpine Foreland regions.</p><p>Penck, A., & Brückner, E. (1909). Die Alpen im Eiszeitalter. Leipzig: Tauchnitz.</p>

scholarly journals River Discharge Simulation in the High Andes of Southern Ecuador Using High-Resolution Radar Observations and Meteorological Station Data

2019 ◽  
Vol 11 (23) ◽  
pp. 2804 ◽  
Author(s):  
Diego Mejía-Veintimilla ◽  
Pablo Ochoa-Cueva ◽  
Natalia Samaniego-Rojas ◽  
Ricardo Félix ◽  
Juan Arteaga ◽  
...  
Keyword(s):  
High Resolution ◽  
River Discharge ◽  
Water Resource Management ◽  
Meteorological Station ◽  
Hydrological Simulation ◽  
Radar Observations ◽  
Radar Images ◽  
Extreme Precipitation Events ◽  
Station Data ◽  
High Resolution Radar

The prediction of river discharge using hydrological models (HMs) is of utmost importance, especially in basins that provide drinking water or serve as recreation areas, to mitigate damage to civil structures and to prevent the loss of human lives. Therefore, different HMs must be tested to determine their accuracy and usefulness as early warning tools, especially for extreme precipitation events. This study simulated the river discharge in an Andean watershed, for which the distributed HM Runoff Prediction Model (RPM) and the semi-distributed HM Hydrologic Modelling System (HEC-HMS) were applied. As precipitation input data for the RPM model, high-resolution radar observations were used, whereas the HEC-HMS model used the available meteorological station data. The obtained simulations were compared to measured discharges at the outlet of the watershed. The results highlighted the advantages of distributed HM (RPM) in combination with high-resolution radar images, which estimated accurately the discharges in magnitude and time. The statistical analysis showed good to very good accordance between observed and simulated discharge for the RPM model (R2: 0.85–0.92; NSE: 0.77–0.82), whereas for the HEC-HMS model accuracies were lower (R2: 0.68–0.86; NSE: 0.26–0.78). This was not only due to the application of means values for the watershed (HEC-HMS), but also to limited rain gauge information. Generally, station network density in tropical mountain regions is poor, for which reason the high spatiotemporal precipitation variability cannot be detected. For hydrological simulation and forecasting flash floods, as well as for environmental investigations and water resource management, meteorological radars are the better choice. The greater availability of cost-effective systems at the present time also reduces implementation and maintenance costs of dense meteorological station networks.

Sign in / Sign up

Export Citation Format

Share Document