scholarly journals Scale breaks of suspended sediment rating in large rivers in Germany induced by organic matter

2020 ◽  
Vol 8 (3) ◽  
pp. 661-678
Author(s):  
Thomas O. Hoffmann ◽  
Yannik Baulig ◽  
Helmut Fischer ◽  
Jan Blöthe
Keyword(s):  
Organic Matter ◽  
Suspended Sediment ◽  
Suspended Matter ◽  
Monitoring Network ◽  
Suspended Sediments ◽  
Low Flow ◽  
Rating Curve ◽  
Organic Fraction ◽  
Sediment Rating Curve ◽  
Aquatic Biomass

Abstract. Understanding the transport of suspended sediment and associated nutrients is of major relevance for sustainable sediment management aiming to achieve healthy river systems. Sediment rating curves are frequently used to analyze the suspended sediments and their potential sources and sinks. Here we use more than 750 000 measurements of suspended sediment concentrations (SSCs) and discharge (Q) collected at 62 gauging stations along 19 waterways in Germany based on the suspended sediment monitoring network of the German water and shipping authority, which started in the 1960s. Furthermore, we analyze more than 2000 measurements of the loss on ignition (LOI) of suspended matter at two stations along the rivers Moselle and Rhine to provide a proxy for the relative contributions of mineral load and organic matter. SSC and LOI are analyzed in terms of the power-law rating curve to identify discharge-dependent controls of suspended matter. Our results indicate that for most studied gauging stations, rating coefficients are not constant over the full discharge range, but there is a distinct break in the sediment rating curve, with specific SSC–Q domains above and below this break. The transition of the rating exponent likely results from increased supply of mineral suspended sediments from hillslope erosion at high flow and a shift of the organic matter sources from aquatic biomass-derived organic matter (i.e., high % LOI) at low flow, to mineral-associated organic matter with low % LOI eroded from hillslopes at higher flow. Based on these findings we developed a conceptual rating model for large (>10 000 km2) and low-turbidity (SSC < 1000 mg L−1) rivers separating the mineral and organic fraction of the suspended matter in German waterways. This model allows evaluating the sources of the mineral and organic fraction of the suspended matter and facilitates new insights into the first-order control of discharge on the quality and quantity of suspended sediments.

scholarly journals Scale-breaks of suspended sediment rating in large rivers in Germany induced by organic matter

2020 ◽  
Author(s):  
Thomas O. Hoffmann ◽  
Yannik Baulig ◽  
Helmut Fischer ◽  
Jan Blöthe
Keyword(s):  
Organic Matter ◽  
Suspended Sediment ◽  
Suspended Matter ◽  
Monitoring Network ◽  
Suspended Sediments ◽  
Sediment Supply ◽  
Organic Fraction ◽  
Sediment Rating Curve ◽  
Suspended Sediment Concentrations ◽  
Rating Model

Abstract. Understanding the dynamics of suspended sediment and associated nutrients is of major relevance for sustainable sediment management aiming to achieve healthy river systems. Sediment rating curves are frequently used to analyze the dynamics of suspended sediments and their potential sources and sinks. Here we are using more than 750 000 measurements of the suspended sediment concentrations (SSC) and discharge at 62 gauging stations along 19 waterways in Germany based on the suspended sediment monitoring network of the German water and shipping authority, which started in the 1960ties. Furthermore, we analyse more than 2000 measurements of the loss on ignition (LOI) of suspended matter at two stations along the rivers Moselle and Rhine to asses the mineral and organic fraction of the suspended matter. SSC and LOI are analysed in terms of the power law rating to identify discharge depended process regimes of suspended matter. Our results indicate that for most studied gauging stations, rating coefficients are not constant over the full discharge range, but there is a distinct break in the sediment rating curve, with specific SSC-Q domains above and below this break. The transition of the rating exponent is likely to be a result of a change of controlling factors of the suspended sediment from intrinsic organic matter formation at low flows to extrinsic sediment supply (including mineral and organic fractions) due to hillslope erosion at high flows. Based on these findings we developed a conceptual rating model separating the mineral and organic fraction of the suspended matter in the Germany waterways. This model allows evaluating the sources of the mineral and organic fraction of the suspended matter and gain new insights into the first order control of discharge dynamics of suspended sediments.

scholarly journals Classifications of runoff and sediment data to improve the rating curve method

2017 ◽  
Vol 48 ◽  
Author(s):  
Hossein Khaledian ◽  
Homayoun Faghih ◽  
Ata Amini
Keyword(s):  
Suspended Sediment ◽  
River Flow ◽  
Data Classification ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Low Flow ◽  
Rating Curve ◽  
Sediment Rating Curve ◽  
Curve Method ◽  
Sediment Data

In this study, data classification method was evaluated to increase accuracy of estimating suspended sediment load. To achieve this objective, suspended sediment in Chehelgazi and Khalifeh-Tarkhan rivers in Kurdistan, Iran, were estimated using Sediment Rating Curve (SRC) method in three different approaches of data classification. At first, measured data were modeled without classification. Then, data based on flow statues were divided into two series as high and low flow. Eventually, based on sediment concentration, the data were divided into low and high sediment concentration. Long-term runoff and sediment data were used to calibrate rating curve model. The estimated values were compared with recorded data and the performances of these models were evaluated using statistical criteria. The results indicated an effective role of data classification to improve estimating sediment transportation by rating curve method. In one of the stations, it was observed that due to classification based on river flow and sediment concentration, model efficiency was increased about 45% and 28%, respectively. Furthermore, in case of improving efficiency of SRC method, classifying data based on flow statues was found to be more effective than sediment concentration. The results of this study can be used to improve the management of the basin by more accurately estimating the amount of suspended sediments transporting in the rivers draining to reservoirs.

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;The sudden increase of the rating exponent coincided with the period that the Ponto-Caspian &lt;em&gt;Chelicorophium curvispinum&lt;/em&gt; (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 &lt;em&gt;Chelicorophium curvispinum&lt;/em&gt; 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 &lt;em&gt;Chelicorophium curvispinum&lt;/em&gt; 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.&lt;/p&gt;

scholarly journals Suspended Sediment Concentration and Sediment Loading of Bernam River (Perak, Malaysia)

2020 ◽  
Vol 22 (2) ◽  
pp. 1-14
Author(s):  
Sumayyah Aimi Mohd Najib ◽  
Syazwani Aliah ◽  
Husna Nabilah Hamidon
Keyword(s):  
Suspended Sediment Concentration ◽  
Sampling Period ◽  
Sediment Concentration ◽  
High Flow ◽  
Low Flow ◽  
Sediment Loading ◽  
Land Uses ◽  
Rating Curve ◽  
Sediment Rating Curve ◽  
Rain Events

Abstract This paper presents some of our preliminary results on the sediment discharge and load based on weekly sampling starting from Oct 2017 to January 2018. Results show that sediment rating curve of Bernam River was R2 = 0.86 high flow and R2 = 0.5 low flow. Average sediment loading throughout this sampling period is 1,144 t. Land use activity is expected to be the main contribution for the highest sediment concentration during rain events. The amount of annual sediment yield was estimated at 23 t/km2/year and is comparable to other studies having similar land uses in the catchment area.

scholarly journals Organic matter dynamics and stable isotope signature as tracers of the sources of suspended sediment

2012 ◽  
Vol 9 (6) ◽  
pp. 1985-1996 ◽  
Author(s):  
Y. Schindler Wildhaber ◽  
R. Liechti ◽  
C. Alewell
Keyword(s):  
Organic Matter ◽  
Suspended Sediment ◽  
Brown Trout ◽  
Arable Land ◽  
Atomic Ratio ◽  
High Flow ◽  
Low Flow ◽  
Organic C ◽  
Sediment Loads ◽  
Temporal And Spatial

Abstract. Suspended sediment (SS) and organic matter in rivers can harm brown trout Salmo trutta by affecting the health and fitness of free swimming fish and by causing siltation of the riverbed. The temporal and spatial dynamics of sediment, carbon (C), and nitrogen (N) during the brown trout spawning season in a small river of the Swiss Plateau were assessed and C isotopes as well as the C/N atomic ratio were used to distinguish autochthonous and allochthonous sources of organic matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes was used to quantify the temporal and spatial sources of SS. Organic matter concentrations in the infiltrated and suspended sediment were highest during low flow periods with small sediment loads and lowest during high flow periods with high sediment loads. Peak values in nitrate and dissolved organic C were measured during high flow and high rainfall, probably due to leaching from pasture and arable land. The organic matter was of allochthonous sources as indicated by the C/N atomic ratio and δ13Corg. Organic matter in SS increased from up- to downstream due to an increase of pasture and arable land downstream of the river. The mean fraction of SS originating from upper watershed riverbed sediment decreased from up to downstream and increased during high flow at all measuring sites along the course of the river. During base flow conditions, the major sources of SS are pasture, forest and arable land. The latter increased during rainy and warmer winter periods, most likely because both triggered snow melt and thus erosion. The measured increase in DOC and nitrate concentrations during high flow support these modeling results. Enhanced soil erosion processes on pasture and arable land are expected with increasing heavy rain events and less snow during winter seasons due to climate change. Consequently, SS and organic matter in the river will increase, which will possibly affect brown trout negatively.

scholarly journals Copula-Based Infilling Methods for Daily Suspended Sediment Loads

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1701
Author(s):  
Jenq-Tzong Shiau ◽  
Yu-Cheng Lien
Keyword(s):  
Suspended Sediment ◽  
Conditional Distribution ◽  
Sediment Load ◽  
Distribution Model ◽  
Rating Curve ◽  
Similar Frequency ◽  
Sediment Rating Curve ◽  
Sediment Loads ◽  
Recorded Data ◽  
Sediment Data

Less-frequent and inadequate sampling of sediment data has negatively impacted the long and continuous records required for the design and operation of hydraulic facilities. This data-scarcity problem is often found in most river basins of Taiwan. This study aims to propose a parsimonious probabilistic model based on copulas to infill daily suspended sediment loads using streamflow discharge. A copula-based bivariate distribution model of sediment and discharge of the paired recorded data is constructed first. The conditional distribution of sediment load given observed discharge is used to provide probabilistic estimation of sediment loads. In addition, four different methods based on the derived conditional distribution of sediment load are used to give single-value estimations. The obtained outcomes of these methods associated with the results of the traditional sediment rating curve are compared with recorded data and evaluated in terms of root mean square error (RMSE), mean absolute percentage error (MAPE), Nash-Sutcliffe efficiency (NSE), and modified Nash-Sutcliffe efficiency (MNSE). The proposed approach is applied to the Janshou station located in eastern Taiwan with recorded daily data for the period of 1960–2019. The results indicate that the infilled sediments by the sediment rating curve exhibit better performance in RMSE and NSE, while the copula-based methods outperform in MAPE and MNSE. Additionally, the infilled sediments by the copula-based methods preserve scattered characteristics of observed sediment-discharge relationships and exhibit similar frequency distributions to that of recorded sediment data.

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