Long-term continuous acoustical suspended-sediment measurements in rivers - Theory, application, bias, and error

2016 ◽  
Author(s):  
David J. Topping ◽  
Scott A. Wright
Keyword(s):  
Suspended Sediment ◽  
Theory Application

Impact of Chelicorophium curvispinum on the concentration-discharge response of suspended sediment in the Rhine River

2021 ◽  
Author(s):  
Marcel van der Perk
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sudden Increase ◽  
Rhine River ◽  
Rating Curve ◽  
Independent Evidence ◽  
Sediment Rating Curve ◽  
Suspended Sediment Concentrations

<p>In an ongoing study to the decline in suspended sediment concentrations and loads in the Rhine river since the mid-1950s, the temporal changes in the power-law sediment rating curve parameters were examined. This revealed that the rating exponent of the rating curve increased substantially between the early and late 1980s. Until the early 1980s, the ratings curves were relatively flat with values of the rating exponent b varying around 0.2. In the mid-1980s, the exponent suddenly increased to a value between 0.4 and 0.6 and since then has remained within this range. This change in the rating exponent was mainly caused by a decrease in suspended sediment concentrations during low discharges. During high discharges, the suspended sediment concentration initially increased during the late 1980s, but this increase was nullified soon afterwards due to the declining trend in suspended sediment concentration.</p><p>The sudden increase of the rating exponent coincided with the period that the Ponto-Caspian <em>Chelicorophium curvispinum</em> (Caspian mud shrimp) invaded the Rhine river basin. This suggests that this suspension-feeder species bears the prime responsibility for this increase, although this hypothesis requires further independent evidence. The sudden increase in the rating exponent does however not manifest itself in the long-term gradual trend of declining suspended sediment concentrations and vice versa. Apparently, the sequestration of sediment by <em>Chelicorophium curvispinum</em> is only temporary: the suspended sediment sequestered during periods of relatively low discharges is likely remobilised again during periods of high discharge. This implies that the invasion of <em>Chelicorophium curvispinum</em> has not played a significant role in the decline of suspended sediment concentrations. The precise reasons for the gradual long-term decline in suspended sediment concentration remain yet unknown.</p>

scholarly journals Hydrological and suspended sediment regime in the Kolubara River during the extreme year of 2014

2016 ◽  
Vol 18 (1) ◽  
pp. 32-46 ◽  
Author(s):  
Slavoljub DRAGIĆEVIĆ ◽  
Nenad ŽIVKOVIĆ ◽  
Ivan NOVKOVIĆ ◽  
Ana PETROVIĆ ◽  
Radislav TOŠIĆ ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Water Discharge ◽  
Suspended Sediment Transport ◽  
Water Runoff ◽  
Sediment Discharge ◽  
Daily Discharge ◽  
Large Water ◽  
Climate Events ◽  
Large Discharge

The previous methodology of sampling and determining the suspended sediment con­cen­tration (SSC) in the rivers of Serbia is characterized by a number of disadvantages, so that any re­search of this kind has a large water management impact. In the largest number of hydrological stations in Serbia, daily SSC were obtained based on only one sampling, which raises the question of the representativeness of such sample. Previous SSC – water discharge relationship and detailed analyses of errors in calculating the suspended sediment transport on the profile of Draževac were done for the year of 2004, when the annual difference was very high, which required a very detailed ana­lysis and methodological improvements. In order to define the sediment regime in the Kolubara River, precise monitoring of SSC has been implemented since 2013. The Kolubara River has an unfavourable water regime which is reflected in the excessiveness of water runoff, with floods that are sudden, expressive and short-term, and long-term low waters, so, that are why it is cha­rac­terized by a large discharge and SSC variability. Incidentally, monitoring also covered the year of 2014, when the area of western Serbia (in particular the Kolubara River Basin) was under the influence of extreme climate events that strongly reflected on the hydrological condition with the absolute highest daily discharge. A total of 220 water samples were collected on Draževac gauging station in 2014, in order to determine SSC and sediment discharge. The total number of days covered was 206, which means that there were even more samplings per day, when the discharge was changing fast. The minimal daily measured SSC was only 0.0016 g/l and the maxi­mal recorded value of SSC was 2.6122 g/l and was measured in May at the water discharge of 1 260 m3/s. Тhe total amount of sus­pended sediment discharge at the profile of Draževac in 2014 was 1 104 435 t (the spe­ci­fic suspended sediment yield – 308 t/sqkm/yr). The main objective of this study is to improve SSC – water discharge relationship in the Kolubara River based on the extreme hydrological conditions in 2014.

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