Network-scale dynamics of grain-size sorting: implications for downstream fining, stream-profile concavity, and drainage basin morphology

2004 ◽  
Vol 29 (4) ◽  
pp. 401-421 ◽  
Author(s):  
Nicole M. Gasparini ◽  
Gregory E. Tucker ◽  
Rafael L. Bras
Keyword(s):  
Grain Size ◽  
Drainage Basin ◽  
Network Scale ◽  
Size Sorting ◽  
Downstream Fining ◽  
Basin Morphology

scholarly journals Climate, tectonics or morphology: what signals can we see in drainage basin sediment yields?

2013 ◽  
Vol 1 (1) ◽  
pp. 13-27 ◽  
Author(s):  
T. J. Coulthard ◽  
M. J. Van de Wiel
Keyword(s):  
Sediment Yield ◽  
Drainage Basin ◽  
Sediment Yields ◽  
Internal Storage ◽  
Storage Effects ◽  
Climatic Drivers ◽  
Basin Morphology ◽  
The Impact ◽  
Small Basin

Abstract. Sediment yields from river basins are typically considered to be controlled by tectonic and climatic drivers. However, climate and tectonics can operate simultaneously and the impact of autogenic processes scrambling or shredding these inputs can make it hard to unpick the role of these drivers from the sedimentary record. Thus an understanding of the relative dominance of climate, tectonics or other processes in the output of sediment from a basin is vital. Here, we use a numerical landscape evolution model (CAESAR) to specifically examine the relative impact of climate change, tectonic uplift (instantaneous and gradual) and basin morphology on sediment yield. Unexpectedly, this shows how the sediment signal from significant rates of uplift (10 m instant or 25 mm a−1) may be lost due to internal storage effects within even a small basin. However, the signal from modest increases in rainfall magnitude (10–20%) can be seen in increases in sediment yield. In addition, in larger basins, tectonic inputs can be significantly diluted by regular delivery from non-uplifted parts of the basin.

scholarly journals Multiple controls on sediment grain properties of Peruvian coastal river basins

2017 ◽  
Author(s):  
Camille Litty ◽  
Fritz Schlunegger ◽  
Willem Viveen
Keyword(s):  
Grain Size ◽  
Drainage Basin ◽  
River Basins ◽  
Humid Climate ◽  
Sediment Properties ◽  
Peruvian Andes ◽  
Southern Group ◽  
Gravel Beds ◽  
The North ◽  
Grain Properties

Abstract. Twenty-one coastal rivers located on the western Peruvian margin were analyzed to determine the relationships between fluvial and environmental processes and sediment grain properties such as grain size, roundness and sphericity. Modern gravel beds were sampled along a north-south transect on the western side of the Peruvian Andes, and at each site the long a-axis and the intermediate b-axis of about 500 pebbles were measured. Morphometric properties such as river gradient, catchment size and discharge of each drainage basin were determined and compared against measured grain properties. Grain size data show a constant value of the D50 percentile all along the coast, but an increase in the D84 and D96 values and an increase in the ratio of the intermediate and the long axis from south to north. Our results then yield better-sorted and less spherical material in the south when compared to the north. No correlations were found between the grain size and the morphometric properties of the river basins when considering the data together. Grouping the results in a northern and southern group shows better-sorted sediments and lower D84 and D96 values for the southern group of basins. Within the two groups, correlations were found between the grain size distributions and morphometric basins properties. Our data indicates that fluvial transport is the dominant process controlling the erosion, transport and deposition of sediment in the southern basins while we propose a geomorphic control on the grain size properties in the northern basins. Sediment properties in the northern and southern basins could not be linked to differences in tectonic controls. On the other hand, the north-south trend in the grain size and in the b/a ratio seems controlled by a shift towards a more humid climate and towards a stronger El Nino impact in northern Peru. But, generally speaking, the resulting trends and differences in sediment properties seem controlled by differences in the complex geomorphic setting along the arc and forearc regions.

Grain size sorting over offshore sandwaves

2007 ◽  
pp. 649-656 ◽  
Author(s):  
Pieter Roos ◽  
Suzanne Hulscher ◽  
Fenneke Meer ◽  
Thaiënne Dijk ◽  
Irene Wientjes ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Sorting

scholarly journals Grain-size sorting in grainflows at the lee side of deltas

Sedimentology ◽  
2005 ◽  
Vol 52 (2) ◽  
pp. 291-311 ◽  
Author(s):  
MAARTEN G. KLEINHANS
Keyword(s):  
Grain Size ◽  
Size Sorting

Progressive grain-size sorting along an intertidal energy gradient

2007 ◽  
Vol 202 (3) ◽  
pp. 464-472 ◽  
Author(s):  
A. Bartholomä ◽  
B.W. Flemming
Keyword(s):  
Grain Size ◽  
Energy Gradient ◽  
Size Sorting

Geomorphic signatures of large-scale glacier detachments

2020 ◽  
Author(s):  
Mylène Jacquemart ◽  
Matthias Leopold ◽  
Ethan Welty ◽  
Lia Lajoie ◽  
Michael Loso ◽  
...  
Keyword(s):  
Grain Size ◽  
Large Scale ◽  
Mountain Communities ◽  
Fluvial Deposits ◽  
Field Evidence ◽  
Grain Orientations ◽  
Grain Size Distributions ◽  
Size Sorting ◽  
Summer Temperatures ◽  
Ice Content

<p>The catastrophic detachment of Kolka Glacier in Russia was long thought to be a unique occurrence (e.g., Haeberli et al., 2004), but recent events in Tibet, Alaska, Argentina and China have increased the urgency to understand these processes and the risk they pose to mountain communities and infrastructure. Most notably, the tongues of two neighboring glaciers in Tibet detached only a few weeks apart in 2016, the first killing nine herders and hundreds of their livestock. In 2013 and 2015 Flat Creek Glacier in Alaska’s Saint Elias Mountains lost half of its total area in two large detachments. The resulting destructive mass flows left a clear scar in the landscape, piling debris up to 30 m thick and spreading it over 8 km<sup>2</sup>. Recent investigations by Kääb et al. (2018), Gilbert et al. (2018) and Jacquemart et al. (in review) suggest that the failures in Tibet and Alaska share three main drivers: temperate ice restricted by a frozen glacier tongue, a clay-rich bed, and increased meltwater input to the base of the glacier, driven by increasing summer temperatures.</p><p>Here we ask whether these glacier detachments are indeed a new, emerging hazard or whether we simply have not previously recognized the signs they leave in the landscape. Only a long-term record of observations stretching beyond the modern satellite era, can reliably answer the question about possibly increasing frequencies. In order to start building some understanding of the nature of such deposits, we investigated the internal structure and landscape setting of the 2013 and 2015 detachment deposits at Flat Creek. We performed electrical resistivity tomography surveys to estimate their ice content and ice distribution. In addition we analyzed grain size distributions and orientations in the deposits to see if they can be clearly distinguished from other glacio-fluvial deposits. To understand if glacier detachments have happened in this region before, we performed the same analysis on large debris deposits found downstream of a neighboring glacier. We combine this field evidence with remote sensing analysis of the temporal evolution of the glaciers and detachment deposits in Alaska, Tibet and Russia to understand the signatures of these catastrophic events in the landscape. Our preliminary results for Alaska show that the glacier itself is a bad indicator of past events, as the ice response quickly masks the detachment. Additionally, we found ice in the deposits to be highly broken up and ground, though never the less able to endure multiple years. Unlike a traditional debris-flow deposits, the glacier-detachment deposits exhibit a lack of grain-size sorting, and the grain orientations appear highly chaotic, with a tendency toward vertical orientations. As such, the deposits appear clearly distinct from the surrounding hillslope, and further analysis will show to what extent they can be distinguished from other glacio-fluvial deposits.</p>

Sign in / Sign up

Export Citation Format

Share Document