Variations Of Suspended Sediment Transport Research Articles

Variations of suspended sediment transport caused by changes in shoreline and bathymetry in the Zhujiang (Pearl) River Estuary in the wet season

Variations of suspended sediment transport caused by changes in shoreline and bathymetry in the Zhujiang (Pearl) River Estuary in the wet season

Spatiotemporal variations of suspended sediment transport in the upstream and midstream of the Yarlung Tsangpo River (the upper Brahmaputra), China

AbstractThe Yarlung Tsangpo River, which flows from west to east across the southern part of the Tibetan Plateau, is the longest river on the plateau and an important center for human habitation in Tibet. Suspended sediment in the river can be used as an important proxy for evaluating regional soil erosion and ecological and environmental conditions. However, sediment transport in the river is rarely reported due to data scarcity. Results from this study based on a daily dataset of 3 years from four main stream gauging stations confirmed the existence of great spatiotemporal variability in suspended sediment transport in the Yarlung Tsangpo River, under interactions of monsoon climate and topographical variability. Temporally, sediment transport or deposition mainly occurred during the summer months from July to September, accounting for 79% to 93% of annual gross sediment load. This coincided with the rainy season from June to August that accounted for 51% to 80% of annual gross precipitation and the flood period from July to September that accounted for approximately 60% of annual gross discharge. The highest specific sediment yield of 177.6 t/km2/yr occurred in the upper midstream with the highest erosion intensity. The lower midstream was dominated by deposition, trapping approximately 40% of total sediment input from its upstream area. Sediment load transported to the midstream terminus was 10.43 Mt/yr with a basin average specific sediment yield of 54 t/km2/yr. Comparison with other plateau‐originated rivers like the upper Yellow River, the upper Yangtze River, the upper Indus River, and the Mekong River indicated that sediment contribution from the studied area was very low. The results provided fundamental information for future studies on soil and water conservation and for the river basin management. Copyright © 2017 John Wiley & Sons, Ltd.

The temporal variation of suspended sediment transport according to the dominance of suspended sediment sources. Case study: the Trotuş river between 2000 and 2014

Based on the data series of average daily streamflow and suspended sediment load recorded between 2000 and 2014 at four gauging stations (Lunca de Sus, Goioasa, Târgu Ocna and Vrânceni), the temporal variation of the suspended sediment transport was investigated according to the prevalence of source areas. Thus, a significant temporal variability (monthly, seasonal, annual) was determined, in close relation with the amount of precipitation and the streamflow. The following equation was determined between the mean monthly suspended sediment load (Ṝ) and the mean discharge (Ǭ) at Vrânceni section: R= 0,0035Q 2,2895 , r=0,899. We believe this relation has a high degree of confidence for the indirect determination of solid load and it is comparable with other equations of this type. Along the entire length of the river, July was the month during which the highest suspended sediment load was recorded, with an average percentage of 37% of the total amount. At the opposite end, December is the month with the lowest documented suspended sediment load, with just 0.5% of the total amount transported annually by the Trotus. As regards the seasonal variability of the suspended sediment load, the following values were determined along the entire length of river Trotus: during the winter season the volume of sediment carried by the river amounts to approx. 2.1% of the total annual transported suspended sediment, the spring season accounts for 33.7% of the annual volume, the summer season accounts for ca. 55.5%, and the fall for 8.7%. In order to plot the R-Q correlation, the wettest, as well as driest years were selected for every gauging station. On the resulting plots, there were identified the thresholds based on which the two sources were separated depending on the area of origin: dominant from the catchment or dominant from the river bed. Overall, during the investigated period on the Trotus river, the river beds contributed with about 21% of the total volume of transported suspended sediment. Depending on the type of the year (wet, dry or normal), the average input of the beds to the annual volume of suspended alluvium was as follows: 4% in wet years; 43% in dry years; 15% in normal years. The total volume of suspended sediment transported through the four sections on the Trotus river between 2000 and 2014 amounted to approx. 39x106 t, thus the average annual volume was 2,598,000 t. A large share of this suspended sediment yield was produced during major floods. For example, at Vrânceni ca. 61% of the total sediment yield for the 15 year-period under investigation resulted from just 3 flood events (2005, 2010 and 2012).

Suspended sediment dynamics at different time scales in the Loushui River, south-central China

Suspended sediment dynamics were investigated in the Loushui River basin, a secondary tributary of the Yangtze River in southern China. The variations of suspended sediment transport were analyzed at different time scales (among different years, monthly and seasonal, and within-flood event) based on 25-year hydrological data from the outlet hydrometric station, and explained by the contribution of flood events, precipitation and human activities. Four stages were classified by the non-parametric statistical method of Pettitt change-point test and Cumulative anomaly test. At the annual scale, the relationship between suspended sediment concentration (SSC) and water discharge (Q) varied at four stages. The suspended sediment load (SSL) showed parabolic relationship with annual precipitation and significantly influenced by floods (contribution averaged at 78% before 1985; at 55% after 2007). SSL drastically decreased after 2007, mainly induced by the construction of the Jiangya reservoir. Sediment ‘store-release’ phenomenon was used to explain the seasonal variations of suspended sediment load. Monthly SSC–Q hysteresis loops indicated that the sediment storage seasons swung between winter/spring and late autumn at different stages. At the within-flood scale, three types of SSC–Q hysteresis loops were observed for the maximum flood events, including clockwise pattern (44%), counter-clockwise pattern (24%) and figure-eight pattern (32%). The variations of SSC–Q hysteresis patterns at four stages implicated the changing suspended sediment source materials with time. During the years 1966–1978, the suspended sediment mainly came from channels for the maximum flood events, while, materials from the upper reaches or slopes dominated the later period 1979–1985 and 2007–2011.

Temporal variation of suspended sediment transport in the Koga catchment, North Western Ethiopia and environmental implications

AbstractEvent sediment transport and yield were studied for 45 events in the upstream part of the 260 km2 agricultural Koga catchment that drains to an irrigation reservoir. Discharge and turbidity data were collected over a period of more than a year, accompanied by grab sampling. Turbidity was very well correlated with the sediment concentrations from the samples (r = 0.99), which allowed us to estimate the temporal patterns of sediment concentrations within events. The hysteresis patterns between discharge and sediment concentrations were analysed to provide insight into the different sediment sources. Anticlockwise patterns are the dominant hysteresis patterns in the area, suggesting smaller contributions of suspended sediment from the river channels than from the hillslopes and agricultural areas. Complicated types of hysteresis patterns were mostly observed for long events with multiple peaks. For a given discharge, sediment yields in August and September, when the catchment was almost completely covered with vegetation, were much smaller than during the rest of the rainy season. The hysteresis patterns and timing suggest that the sediment availability from the agricultural areas and hillslopes affects sediment yields more strongly than does peak discharge. Two distinct types of sediment rating curves were observed for the season when the agricultural land was covered with vegetation and when it was not, indicating the dominating contribution of land use/cover to sediment yields in the catchment. The rate of suspended sediment transport in the area was estimated as 25.6 t year−1 ha−1. Copyright © 2013 John Wiley & Sons, Ltd.

High-Resolution Operational Coastal Modeling System for the Prediction of Hydrodynamics in Korea Using a Wave-Current Coupled Model

Lim, H.S., Chun, I.S., Kim, C.S., Park, K.S., Shim, J.S. and Yoon, J.J, 2013. High-Resolution Operational Coastal Modeling System for the Prediction of Hydrodynamics in Korea Using a Wave-Current Coupled ModelWe have developed a high-resolution operational coastal modeling system for the coastal waters of Korea using a wave-current coupled model ROMS. The operational oceanographic system consists of operational modeling and monitoring modules. The modeling system comprises atmospheric and hydrodynamic models coupled with three-dimensional hydrodynamics, wave, sediment transport, and water quality model. The hydrodynamic variables are forecasted on a 72-hour basis. The real-time monitoring system is comprised of buoy, HF-radar and geostationary Communication Ocean Meteorological Satellite (COMS). The web-GIS-based coastal information system provides predicted results with real-time monitoring data for dissemination to the public and validation of the predicted results. The operational coastal modeling system uses the ROMS hydrodynamic model coupled with SWAN, a wave model. WRF is used for meteorological modeling of atmospheric forcing, NAO.99jb is a regional tide model used for the tides, and CE-QUAL-ICM is an eutrophication model that is used for simulating the water quality. The atmospheric forcing is derived from the predicted results of the WRF atmospheric model, which has been operated for forecasting in the East China Sea and East Sea. The ocean boundary condition is derived from data-assimilative ROMS, which has been in operation for the Yellow Sea. The hydrodynamic variables were calibrated with tidal surface elevation and verified with current data observed by a bottom-mounted ADCP and AWAC. To validate the predicted results, we use real-time monitoring data from hydrodynamic measurements observed by the operational AWAC and buoy, 1-h averaged surface currents measured by HF-radar, and suspended sediment concentration (SSC) obtained hourly and derived from the Geostationary Ocean Color Imager (GOCI) of COMS. The wave-current coupled ROMS-SWAN modeling system shows enhanced wave-current interaction for the coastal waters of Korea, especially for the prediction of storm surge height and variation of suspended sediment transport. This operational coastal modeling system has been originally developed for the prediction system of coastal waters of Korea and used for the development of an Integrated-Maritime Prediction System (I-MAPS) supporting the operation of the major ports system of Korea such as Incheon and Gunsan on the western coast of Korea, and Yeosu, Masan and Busan on the southern coast of Korea. I-MAPS will also provide monitoring and predicted data to governmental agencies and to the public to support ship navigation and marine activity and to solve problems associated with coastal accidents, such as storm surge, inundation, search and rescue, and oil-spills, as a part of the Korea Operational Oceanographic System (KOOS) which will be in operation by the end of 2013.

Temporal variations of suspended sediment transport in three small catchments of the Basque Country

Temporal variations of suspended sediment transport in three small catchments of the Basque Country

Temporal variations of suspended sediment transport in Oneida Creek watershed, central New York

► The exponent of a sediment rating curve reflects the degree of sediment supply. ► Short-term sediment variations can be averaged out at longer time scales. ► A process-based approach for seasonal sediment loads and sediment yields. Using event-based suspended sediment data collected from 2008 to 2010 in a medium-size agricultural watershed in Central New York, we first examined the statistical properties of suspended sediment concentration, C and the associated water discharge, Q . Next, we identified two different transport processes in two discharge ranges separated by a different threshold Q t for each season. Different exponents of sediment rating curves (SRCs) in each season revealed that sediment was transported near capacity during lower discharges but well below capacity during higher discharges. The persistence of these two trends in all seasons suggested that suspended sediment transport was generally supply limited. Sediment loads predicted by a single seasonal SRC are similar to those predicted by the two separate SRCs for above and below Q t , which suggests that the two transport processes are not significantly different and seasonal sediment transport may be described by a single SRC. The better fit of SRC for the combined 3-year data compared to those for individual years indicates that seasonal changes of suspended sediment transport are limited and the transport dynamics that emerge at shorter time scales (i.e., event and season) are effectively averaged out. We then calculated sediment yields for 3 years using a process-based SRC method: annual hydrograph was divided into storm and base flows using values of Q t for all seasons and only storm flows were used to calculate sediment yields based on the developed SRCs. Comparing sediment yields of 3 years calculated using three seasonal SRCs to those using the combined 3-year SRC indicated that the discrepancies between the two were less than 5%, suggesting that sediment yield may be accurately estimated using the single combined-year SRC. Finally, we discussed the appropriate sampling strategy in the region and demonstrated geomorphological nature of sediment transport based on the calculated effective discharges and cumulative sediment loads.