Laboratory Measurement of High Sediment Concentration with Light Extinction Method

When oil spills occur in turbid waters, the oil droplets and mineral grains can combine to form oil-particle aggregates (OPAs). The formation of OPAs impacts the vertical transport of both the oil and the mineral grains; especially increasing deposition of oil to the seabed. Though the coastal oceans can be very turbid, to date, few numerical ocean models have accounted for aggregation processes that form OPAs. However, interactions between oil and mineral aggregates may be represented using techniques developed to account for sediment aggregation. As part of Consortium for Simulation of Oil Microbial Interactions in the Ocean (CSOMIO), we modified an existing, population dynamics-based sediment flocculation model to develop OPAMOD, a module that accounts for the formation of OPAs. A zero-dimensional model using OPAMOD is shown to be capable of reproducing the size distribution of aggregates from existing laboratory experimental results. Also using the zero-dimensional model, sensitivity tests were performed on two model parameters, the fractal dimension and collision efficiency. Results showed that fractal dimension played a role in the OPA size distribution by influencing the effective particle density, which modified the number concentration of flocs for a given mass concentration. However, the modeled particle characteristics and oil sequestration were relatively insensitive to collision efficiency. To explore OPA formation for an outer continental shelf site, two simulations were conducted using a one-dimensional (vertical) implementation of the model. One scenario had high sediment concentration near the seabed to mimic storm-induced resuspension. The other scenario represented river plume sediment delivery by having high sediment concentration in surface waters. Results showed that OPA formation was sensitive to the vertical distribution of suspended sediment, with the river plume scenario creating more OPA, and sequestering more oil within OPA than the storm resuspension scenario. OPAMOD was developed within the Coupled Ocean-Atmosphere-Wave-and-Sediment Transport (COAWST) modeling system, therefore the methods and parameterizations from this study are transferrable to a three-dimensional coupled oil-sediment-microbial model developed by CSOMIO within the COAWST framework.

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Hydrogeology of Volcanic Highlands Affects Prioritization of Land Management Practices

Water ◽

10.3390/w12102702 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2702 ◽

Cited By ~ 1

Author(s):

Anwar A. Adem ◽

Gashaw G. Addis ◽

Dessalew W. Aynalem ◽

Seifu A. Tilahun ◽

Wolde Mekuria ◽

...

Keyword(s):

Water Management ◽

Soil Degradation ◽

Management Practices ◽

Potable Water ◽

Water Source ◽

Sediment Concentration ◽

Agricultural Watershed ◽

Land And Water Management ◽

High Sediment ◽

Tertiary Basalt

Volcanic highlands supply water to 40% of the world’s population. Soil degradation threatens this water supply. Studies on geohydrology that affect the effectiveness of land and water management (LWM) practices in reducing soil degradations are limited. To aid in the effectiveness of LWM practices, we conducted a field experiment in the Gomit watershed in the semihumid Ethiopian Highlands on the interaction of hydrogeology and LWM practices. We found that in a watershed with strongly faulted tertiary basalt, 30% of the rainfall was drained through faults to another basin. Consequently, the discharge at the outlet was less than half of that of other watersheds with quaternary basalts. Despite the high sediment concentration, i.e., around 15 g L−1, in the Gomit watershed, the sediment yield of less than 4 Mg ha−1 a−1 was below average for the agricultural watershed in Ethiopia because of the low runoff response. While some faults facilitated drainage, others acted as a barrier. Groundwater stored behind the barriers was used as a municipal potable water source. Since the effectiveness of LWM practices depends on the amount of erosion that can be prevented, considerations of country-wide prioritizing of investments in land and water management practices should include the geology of the watersheds.

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Sedimentation in proglacial Sunwapta Lake, Alberta

Canadian Journal of Earth Sciences ◽

10.1139/e81-007 ◽

1981 ◽

Vol 18 (1) ◽

pp. 81-93 ◽

Cited By ~ 54

Author(s):

Robert Gilbert ◽

John Shaw

Keyword(s):

Water Movement ◽

Fine Sand ◽

Sediment Concentration ◽

Turbidity Currents ◽

Canadian Rocky Mountains ◽

Sedimentary Characteristics ◽

Suspended Sediment Concentrations ◽

Continuous Sedimentation ◽

Lake Floor ◽

High Sediment

The hydrologic and limnologic conditions of Sunwapta Lake, a small proglacial lake in the Canadian Rocky Mountains, were investigated with special reference to the sedimentology of this lake. Discharge and suspended sediment concentrations of the inflowing streams were measured to give estimates of sediment input. Distribution of large loads of fine glacial sediment is largely by an inflow- and wind-controlled circulation, which commonly fluctuates diurnally. The spatial distribution of sedimentation was determined by use of sediment-collecting pans placed on the lake bed. Turbidity currents are rare with only one event monitored in 2 years. This event was caused by a burst of highly sediment-charged inflow water. The rarity of turbidity currents is attributed to the high sediment concentration in the lake water, which results from the small size of the lake in relation to the inflow. Wind-generated water movement at the lake floor ranges from 0.0–0.03 m/s while the maximum recorded velocity of the turbidity currents was 0.32 m/s.Sedimentation rates are calculated and six cores from the lake bed, each containing sediment deposited over several years, are described. Although bedding and lamination are found in all cores, correlation between cores was not possible. Sedimentary characteristics are related to inflow and lake conditions: laminated and massive beds of medium to fine sand and silt are related to turbidity events, graded laminae in coarse and fine silt to diurnal variations in lake currents, and massive beds in silt to periods of continuous sedimentation without diurnal variation. Deformed beds result from subaqueous slumps.

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Analysis on the Runoff and Sediment Yielding of “7.26” Rainstorm in 2017 in the Dali River Basin

E3S Web of Conferences ◽

10.1051/e3sconf/20185303025 ◽

2018 ◽

Vol 53 ◽

pp. 03025

Author(s):

WenYong Gao ◽

ShuangYan Jin ◽

ShaoMeng Guo

Keyword(s):

Ecological Restoration ◽

River Basin ◽

High Intensity ◽

Soil Conservation ◽

Sediment Concentration ◽

Peak Discharge ◽

Underlying Surface ◽

The Relationship ◽

High Sediment ◽

Hydrological Regimes

Hydrological regimes of the “7.26” rainstorm and flood in 2017 in the Dali River basin are illustrated, the runoff and sediment of the flood is calculated. The relationship between peak discharge, runoff and sediment of history floods and the corresponding mean rainfall and combined rainfall factor are established respectively. It is found that the point of “7.26” flood locates at the upper left or in the middle of the history points group. The results show that after the implementation of water and soil conservation and ecological restoration policy for several decades, the underlying surface of the Dali River basin has changed to some degree, but encountered with the high intensity rainfall such as "7.26", it will still generate the flood of high sediment concentration.

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The 1987–88 surge of West Fork Glacier, Susitna Basin, Alaska, U.S.A.

Journal of Glaciology ◽

10.1017/s0022143000007334 ◽

1994 ◽

Vol 40 (135) ◽

pp. 241-254 ◽

Cited By ~ 39

Author(s):

W. D. Harrison ◽

K. A. Echelmeyer ◽

E. F. Chacho ◽

C. F. Raymond ◽

R.J. Benedict

Keyword(s):

Water Discharge ◽

Drainage System ◽

High Water ◽

Sediment Concentration ◽

Maximum Displacement ◽

Alaska Range ◽

West Fork ◽

Termination Phase ◽

Fast Motion ◽

High Sediment

AbstractA surge of West Fork Glacier, a temperate glacier in the Susitna Basin of the Alaska Range, began soon after the end of the 1987 melt season and terminated on 6 July 1988. Reconnaissance measurements of balance, elevation and speed had been made from 1981 to 1983. Daily measurements of surface speed at two points 9 km apart and of the characteristics of the stream draining the glacier were begun during the surge and continued through the following year. The maximum displacement of the ice during the surge was about 4 km; the maximum change in surface elevation was about 120 m. Between the time of the start of detailed observations on 12 February 1988 and the onset of a complex termination phase during the last month of the surge, the speed was almost constant, and the water discharge was totally free of turbidity, indicating that no basal water was escaping from the glacier. During the termination phase, sharp changes in speed occurred, almost simultaneously at the two observation sites; each deceleration event was accompanied by high sediment concentration and high water discharge. This behavior is similar to that observed on Variegated Glacier during its 1982-83 surge. The mechanism of triggering (related to surface water input and the disruption of the internal drainage system) and the cause of the fast motion were probably the same for both surges, even though there are substantial differences in size and mass-balance characteristics.

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SIMULATION OF SORTING SEDIMENTATION IN THE CHANNEL OF HUANGHUA HARBOR BY USING 3D MULTI-SIZED SEDIMENT TRANSPORT MODEL OF EFDC

Coastal Engineering Proceedings ◽

10.9753/icce.v32.sediment.22 ◽

2011 ◽

Vol 1 (32) ◽

pp. 22

Author(s):

Qinghe Zhang ◽

Feng Tan ◽

Tao Han ◽

Xiaoyuan Wang ◽

Zhiqiang Hou ◽

...

Keyword(s):

Sediment Transport ◽

Transport Model ◽

Sediment Concentration ◽

Bohai Bay ◽

Storm Events ◽

South West ◽

Sea Bed ◽

South West Coast ◽

Efdc Model ◽

High Sediment

Huanghua Harbor, located in the south-west coast of Bohai Bay, China, has frequently encountered severe channel siltation with sorting sedimentation along the channel during storm events since its construction. For prediction of channel siltation, a 3D numerical model of multi-fraction sediment transport based on the coupling of modified EFDC model and SWAN model is developed to investigate the sediment transport. It is shown from simulated results that the sorted sedimentation in the channel was well simulated in storm events, and the high sediment concentration near sea bed for silty coast during storm process can also be basically reflected by the model.

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