scholarly journals Fine Sediment Modeling During Storm-Based Events in the River Bandon, Ireland

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1523 ◽  
Author(s):  
Juan T. García ◽  
Joseph R. Harrington
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Fine Sediment ◽  
Storm Event ◽  
Storm Events ◽  
Event Scale ◽  
Model Based ◽  
Sediment Volume ◽  
Bed Erosion

The River Bandon located in County Cork (Ireland) has been time-continuously monitored by turbidity probes, as well as automatic and manual suspended sediment sampling. The current work evaluates three different models used to estimate the fine sediment concentration during storm-based events over a period of one year. The modeled suspended sediment concentration is compared with that measured at an event scale. Uncertainty indices are calculated and compared with those presented in the bibliography. An empirically-based model was used as a reference, as this model has been previously applied to evaluate sediment behavior over the same time period in the River Bandon. Three other models have been applied to the gathered data. First is an empirically-based storm events model, based on an exponential function for calculation of the sediment output from the bed. A statistically-based approach first developed for sewers was also evaluated. The third model evaluated was a shear stress erosion-based model based on one parameter. The importance of considering the fine sediment volume stored in the bed and its consolidation to predict the suspended sediment concentration during storm events is clearly evident. Taking into account dry weather periods and the bed erosion in previous events, knowledge on the eroded volume for each storm event is necessary to adjust the parameters for each model.

scholarly journals Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density and boundary conditions

2018 ◽  
Author(s):  
Jérémy Lepesqueur ◽  
Renaud Hostache ◽  
Núria Martínez-Carreras ◽  
Emmanuelle Montargès-Pelletier ◽  
Christophe Hissler
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Small Scale ◽  
Sediment Grain Size ◽  
Model Based

Abstract. Hydromorphodynamic models are powerful tools to predict the potential mobilization and transport of sediment in river ecosystems. Recent studies even showed that they are able to satisfyingly predict suspended sediment matter concentration in small river systems. However, modelling exercises often neglect suspended sediment properties (e.g. particle site distribution and density), even though such properties are known to directly control the sediment particle dynamics in the water column during rising and flood events. This study has two objectives. On the one hand, it aims at further developing an existing hydromorphodynamic model based on the dynamic coupling of TELEMAC-3D (v7p1) and SISYPHE (v7p1) in order to enable an enhanced parameterisation of the sediment grain size distribution with distributed sediment density. On the other hand, it aims at evaluating and discussing the added-value of the new development for improving sediment transport and riverbed evolution predictions. To this end, we evaluate the sensitivity of the model to sediment grain size distribution, sediment density and suspended sediment concentration at the upstream boundary condition. As a test case, the model is used to simulate a flood event in a small scale river, the Orne River in North-eastern France. The results show substantial discrepancies in bathymetry evolution depending on the model setup. Moreover, the sediment model based on an enhanced sediment grain size distribution (10 classes) and with distributed sediment density outperforms the model with only two sediment grain size classes in terms of simulated suspended sediment concentration.

scholarly journals Seasonal variability in hydrologic-system response to intense rain events, Matanuska Glacier, Alaska, U.S.A.

1999 ◽  
Vol 28 ◽  
pp. 267-271 ◽  
Author(s):  
Jon C. Denner ◽  
Daniel E. Lawson ◽  
Grahame J. Larson ◽  
Edward B. Evenson ◽  
Richard B. Alley ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Drainage System ◽  
Fold Increase ◽  
Sediment Concentration ◽  
System Response ◽  
Storm Event ◽  
Suspended Sediment Concentrations ◽  
Rain Events ◽  
Matanuska Glacier

AbstractTwo rain events at Matanuska Glacier illustrate how subglacial drainage system development and snowpack conditions affect hydrologic response at the terminus. On 21 and 22 September 1995, over 56 mm of rain fell in the basin during a period usually characterized by much drier conditions. This event caused an 8-fold increase in discharge and a 47-fold increase in suspended-sediment concentration. Peak suspended-sediment concentration exceeded 20 kg m —3, suggesting rapid evacuation of stored sediment. While water discharge returned to its pre-storm level nine days after the rain ceased, suspended- sediment concentrations took about 20 days to return to pre-storm levels. These observations suggest that the storm influx late in the melt season probably forced subglacial water into a more distributed system. In addition, subglacially transported sediments were supplemented to an unknown degree by the influx of storm-eroded sediments off hillslopes and from tributary drainage basins.A storm on 6 and 7 June 1997, dropped 28 mm of rain on the basin demonstrating the effects of meltwater retention in the snowpack and englacial and subglacial storage early in the melt season. Streamflow before the storm event was increasing gradually owing to warming temperatures; however, discharge during the storm and the following week increased only slightly. Suspended-sediment concentrations increased only a small amount, suggesting the drainage system was not yet well developed, and much of the run off occurred across the relatively clean surface of the glacier or through englacial channels.

Tide-induced fine sediment resuspension in the well-mixed Hangzhou Bay, East China Sea, China

2011 ◽  
Vol 102 (1) ◽  
pp. 25-34 ◽  
Author(s):  
John Z. Shi
Keyword(s):  
Suspended Sediment ◽  
East China Sea ◽  
Suspended Sediment Concentration ◽  
Sediment Resuspension ◽  
Sediment Concentration ◽  
Fine Sediment ◽  
East China ◽  
Hangzhou Bay ◽  
China Sea ◽  
Suspended Sediment Concentrations

ABSTRACTHangzhou Bay is a typical funnel-shaped high turbid estuary along a mesotidal coast of the East China Sea. In this paper, field studies are undertaken in an attempt to better understand tide-induced fine sediment transport processes in the Bay. Field observations were made mainly of current velocities (speeds and directions) and suspended sediment concentrations at six different relative depths and two stations in September 1992. Results show that (1) high near-bed suspended sediment concentrations varied from 1·81 to 4·00 kg m−3 during the spring tide and from 1·04 to 8·00 kg m−3 during the neap tide; (2) tide-induced near-bed fine sediment resuspension processes are indicated by several periodic suspended sediment concentration peaks; and (3) a hysteresis effect, or suspension-lag, occurs in suspended sediment concentration and resuspension events. Tide-induced fine sediment processes are mainly responsible for very high concentration suspensions of fine sediments in Hangzhou Bay. The occurrence of the suspension-lag phenomenon is likely to be common in other similar muddy tidal environments.

scholarly journals Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density, and suspended sediment concentrations at the upstream boundary

2019 ◽  
Vol 23 (9) ◽  
pp. 3901-3915 ◽  
Author(s):  
Jérémy Lepesqueur ◽  
Renaud Hostache ◽  
Núria Martínez-Carreras ◽  
Emmanuelle Montargès-Pelletier ◽  
Christophe Hissler
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sediment Grain Size ◽  
Model Based ◽  
Model Set

Abstract. Hydromorphodynamic models are powerful tools for predicting the potential mobilization and transport of sediment in river ecosystems. Recent studies have shown that they are able to predict suspended sediment matter concentration in small river systems satisfactorily. However, hydro-sedimentary modelling exercises often neglect suspended sediment properties (e.g. sediment densities and grain-size distribution), which are known to directly control sediment dynamics in the water column during flood events. The main objective of this study is to assess whether a better representation of such properties leads to an improved performance in the model. The modelling approach utilizes a fully coupled hydromorphodynamic model based on TELEMAC-3D (v7p1) and an enhanced version of the sediment transport module SISYPHE (based on v7p1), which allows for a refined sediment representation (i.e. 10-class sediment mixtures instead of 2-class mixtures and distributed sediment density instead of uniform). The proposed developments of the SISYPHE model enable us to evaluate and discuss the added value of sediment representation refinement for improving sediment transport and riverbed evolution predictions. To this end, we used several model set-ups to evaluate the influence of sediment grain-size distribution, sediment density, and suspended sediment concentration at the upstream boundary on model predictions. As a test case, we simulated a flood event in a small-scale river, the Orne river in north-eastern France. Depending on the model set-up, the results show substantial discrepancies in terms of simulated bathymetry evolutions. Moreover, the model based on an enhanced configuration of the sediment grain-size distribution (10 classes of particle sizes) and with distinct densities per class outperforms the standard SISYPHE configuration, with only two sediment grain-size classes, in terms of simulated suspended sediment concentration.

Neural networks approached for modelling river suspended sediment concentration due to tropical storms

2013 ◽  
Vol 11 (4) ◽  
pp. 457-466
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Time Series Data ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Series Data ◽  
Generalized Regression Neural Network ◽  
Event Based

Artificial neural networks are one of the advanced technologies employed in hydrology modelling. This paper investigates the potential of two algorithm networks, the feed forward backpropagation (BP) and generalized regression neural network (GRNN) in comparison with the classical regression for modelling the event-based suspended sediment concentration at Jiasian diversion weir in Southern Taiwan. For this study, the hourly time series data comprised of water discharge, turbidity and suspended sediment concentration during the storm events in the year of 2002 are taken into account in the models. The statistical performances comparison showed that both BP and GRNN are superior to the classical regression in the weir sediment modelling. Additionally, the turbidity was found to be a dominant input variable over the water discharge for suspended sediment concentration estimation. Statistically, both neural network models can be successfully applied for the event-based suspended sediment concentration modelling in the weir studied herein when few data are available.

Sign in / Sign up

Export Citation Format

Share Document