Flow and mass transport in vegetated surface waters

2012 ◽  
pp. 389-414
Keyword(s):  
Mass Transport ◽  
Surface Waters ◽  
Flow And Mass Transport

scholarly journals Landslide-Induced Mass Transport of Radionuclides along Transboundary Mailuu-Suu River Networks in Central Asia

2021 ◽  
Vol 13 (4) ◽  
pp. 698 ◽  
Author(s):  
Fengqing Li ◽  
Isakbek Torgoev ◽  
Damir Zaredinov ◽  
Marina Li ◽  
Bekhzod Talipov ◽  
...  
Keyword(s):  
Mass Transport ◽  
Surface Waters ◽  
Natural Radionuclides ◽  
River Basin Management ◽  
River Networks ◽  
Pollution Dispersion ◽  
Continuous Release ◽  
Political Conflicts ◽  
Exposure Pathway ◽  
Analysis System

Seismically triggered landslides are a major hazard and have caused severe secondary losses. This problem is especially important in the seismic prone Mailuu-Suu catchment in Kyrgyzstan, as it hosts disproportionately sensitive active or legacy uranium sites with deposited radioactive extractive wastes. These sites show a quasi-continuous release of radioactive contamination into surface waters, and especially after natural hazards, a sudden and massive input of pollutants into the surface waters is expected. However, landslides of contaminated sediments into surface waters represent a substantial exposure pathway that has not been properly addressed in the existing river basin management to date. To fill this gap, satellite imagery was massively employed to extract topography and geometric information, and the seismic Scoops3D and the one-dimensional numerical model, Hydrologic Engineering Centre, River Analysis System (HEC-RAS), were chosen to simulate the landslide-induced mass transport of total suspended solids (TSS) and natural radionuclides (Pb-210 as a proxy for modeling purposes) within the Mailuu-Suu river networks under two earthquake and two hydrological scenarios. The results show that the seismically vulnerable areas dominated in the upstream areas, and the mass of landslides increased dramatically with the increase of earthquake levels. After the landslides, the concentrations of radionuclides increased suddenly and dramatically. The peak values decreased along the longitudinal gradient of river networks, with the concentration curves becoming flat and wide in the downstream sections, and the transport speed of radionuclides decreased along the river networks. The conclusions of this study are that landslides commonly release a significant amount of pollutants with a relatively fast transport along river networks. Improved quantitative understanding of waterborne pollution dispersion across national borders will contribute to better co-ordination between governments and regulatory authorities of riparian states and, consequently, to future prevention of transnational political conflicts that have flared up in the last two decades over alleged pollution of transboundary water bodies.

scholarly journals Stochastic Risk and Uncertainty Analysis for Shale Gas Extraction in the Karoo Basin of South Africa

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Abdon Atangana ◽  
Gerrit van Tonder
Keyword(s):  
South Africa ◽  
Mass Transport ◽  
Sampling Method ◽  
Latin Hypercube Sampling ◽  
Transport Equations ◽  
Upward Migration ◽  
Karoo Basin ◽  
Fracking Fluid ◽  
Stochastic Risk ◽  
Flow And Mass Transport

We made use of groundwater flow and mass transport equations to investigate the crucial potential risk of water pollution from hydraulic fracturing especially in the case of the Karoo system in South Africa. This paper shows that the upward migration of fluids will depend on the apertures of the cement cracks and fractures in the rock formation. The greater the apertures, the quicker the movement of the fluid. We presented a novel sampling method, which is the combination of the Monte Carlo and the Latin hypercube sampling. The method was used for uncertainties analysis of the apertures in the groundwater and mass transport equations. The study reveals that, in the case of the Karoo, fracking will only be successful if and only if the upward methane and fracking fluid migration can be controlled, for example, by plugging the entire fracked reservoir with cement.

Simulation of Flow and Mass Transport in a Meander Microchannel Subject to Electroosmotic Pumping

2003 ◽  
Author(s):  
Dominik P. J. Barz ◽  
Peter Ehrhard
Keyword(s):  
Mass Transport ◽  
Double Layers ◽  
Complex Flow ◽  
Electrical Field ◽  
Electrical Fields ◽  
Electrical Double Layers ◽  
Electroosmotic Pumping ◽  
Pressure Driven Flow ◽  
Flow And Mass Transport ◽  
Pressure Driven

We have investigated the flow and mass transport within an electroosmotically-pumped incompressible liquid through a meander microchannel system. We employ two-dimensional, time-dependent Finite Element simulations in conjunction with a matched asymptotic treatment of the electrical double layers. The electroosmotic pumping is realized for two idealized and two realistic electrical fields, while a pressure-driven flow is used for comparison. We focus on the aspects of the electroosmotic transport. We find for most of the electroosmotically-driven cases rather complex flow fields, involving recirculation regions. These recirculation regions in all cases increase dispersion. (i) The least dispersion is associated with a plug-type velocity profile, which is obtained for an idealized purely wall-tangential orientation of the electrical field. (ii, iii) We find that both, the idealized horizontal electrical field and the real electrical field between two vertical plates give considerably higher dispersion than the pressure-driven flow. Vertical plate electrodes, therefore, do not allow for a electrical field, which minimizes dispersion. (iv) The arrangement of two point electrodes at the in and out sections likewise proves to be no optimal means to reduce dispersion beyond the pressure-driven flow. Thus, meander geometries of channels, in general, cause severe problems if electroosmotic pumping needs to be achieved in combination with minimized dispersion.

scholarly journals Model simulation and experiments of flow and mass transport through a nano-material gas filter

2013 ◽  
Vol 37 (20-21) ◽  
pp. 9052-9062 ◽  
Author(s):  
Xiaofan Yang ◽  
Zhongquan Charlie Zheng ◽  
Slawomir Winecki ◽  
Steve Eckels
Keyword(s):  
Mass Transport ◽  
Model Simulation ◽  
Nano Material ◽  
Flow And Mass Transport
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