scholarly journals Variations of Fluvial Sediment Transport after Large Earthquakes: Field Study in Taiwan Catchments

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1836 ◽  
Author(s):  
Guan-Wei Lin

By estimating long-term suspended sediment discharges around river catchments, recovery periods of fluvial sediment transport after a large earthquake can be assessed. This study proved that the recovery period in a given catchment is positively correlated with the peak ground motions triggered by an earthquake. The correlation indicates that a recovery period of more than four years is required if a catchment is affected by an earthquake with a ground acceleration greater than 400 gal (~0.4 g). A total of four factors (sediment transport, seismic frequency, rock strength, and joint density) in the multivariate analysis were carefully considered to assess their influence on the sediment yield. As expected, runoff and geomaterial properties were the most important factors affecting the amount of suspended sediment discharges. The analysis of the influence factors further revealed that earthquake frequency is another important factor for sediment yield, especially within a few years after a large earthquake.

1995 ◽  
Vol 19 (4) ◽  
pp. 500-519 ◽  
Author(s):  
A.P. Nicholas ◽  
P.J. Ashworth ◽  
M.J. Kirkby ◽  
M.G. Macklin ◽  
T. Murray

Variations in fluvial sediment transport rates and storage volumes have been described previously as sediment waves or pulses. These features have been identified over a wide range of temporal and spatial scales and have been categorized using existing bedform classifications. Here we describe the factors controlling the generation and propagation of what we term sediment slugs. These can be defined as bodies of clastic material associated with disequilibrium conditions in fluvial systems over time periods above the event scale. Slugs range in magnitude from unit bars (Smith, 1974) up to sedimentary features generated by basin-scale sediment supply disturbances (Trimble, 1981). At lower slug magnitudes, perturbations in sediment transport are generated by local riverbank and/or bed erosion. Larger-scale features result from the occurrence of rare high- magnitude geomorphic events, and the impacts on water and sediment production of tectonics, glaciation, climate change and anthropogenic influences. Simple sediment routing functions are presented which may be used to describe the propagation of sediment slugs in fluvial systems. Attention is drawn to components of the fluvial system where future research is urgently required to improve our quantitative understanding of drainage-basin sediment dynamics.


Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3173
Author(s):  
Valentin Golosov ◽  
Anatoly Tsyplenkov

This paper discusses the joint impact of catchment complexity in topography, tectonics, climate, landuse patterns, and lithology on the suspended sediment yield (SSY, t km−2 year−1) in the Caucasus region using measurements from 244 gauging stations (GS). A Partial Least Square Regression (PLSR) was used to reveal the relationships between SSY and explanatory variables. Despite possible significant uncertainties on the SSY values, analysis of this database indicates clear spatial patterns of SSY in the Caucasus. Most catchments in the Lesser Caucasia and Ciscaucasia are characterized by relatively low SSY values (<100–150 t km−2 year−1), the Greater Caucasus region generally have higher SSY values (more than 150–300 t km−2 year−1). Partial correlation analyses demonstrated that such proxies of topography as height above nearest drainage (HAND) and normalized steepness index (Ksn) tend to be among the most important ones. However, a PLSR analysis suggested that these variables’ influence is likely associated with peak ground acceleration (PGA). We also found a strong relationship between land cover types (e.g., barren areas and cropland) and SSY in different elevation zones. Nonetheless, adding more gauging stations into analyses and more refined characterizations of the catchments may reveal additional trends.


1999 ◽  
Vol 36 (8) ◽  
pp. 1267-1280 ◽  
Author(s):  
Michael Church ◽  
Darren Ham ◽  
Marwan Hassan ◽  
Olav Slaymaker

This report presents a set of maps of regional fluvial sediment yield in Canada, based mainly on the Water Survey of Canada archive of riverine suspended sediment observations. Regional scaling relations for the variation of suspended sediment load with drainage basin area are established to permit data to be adjusted to common areal bases for portrayal of regional variations. For most regions, the specific sediment yield increases downstream, indicating regional degradation of river valleys. In the southern prairies, however, regional aggradation is occurring, and in southern Ontario similar quantities of fluvial sediment are apparently being yielded, on average, over all scales in the landscape. A smoothed regional portrayal of the results is obtained by kriging, which also yields error estimates for locally predicted values of sediment yield. Maps are presented for the standard areas of 1 km2, 102 km2 (10 km × 10 km), and 104 km2 (102 km × 102 km).


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