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Erosion
Published in Karlheinz Spitz, John Trudinger, Mining and the Environment, 2019
Karlheinz Spitz, John Trudinger
Three design criteria are used in sizing the settling zone of a sediment basin, namely “surface area” (defined as design volumetric flow rate divided by the settling velocity of the design particle), depth, and the ratio of length to width. It is common practice in tropical surface mines to install multiple sediment basins, one flowing into the next. Another feature is the use of baffles within the sediment basin to increase detention time, thereby increasing sediment deposition. The final basin design must allow for sediment storage for either the entire duration of soil loss or until the basin is cleaned out.
Controlling Agricultural Runoff by Use of Constructed Wetlands
Published in Gerald A. Moshiri, Constructed Wetlands for Water Quality Improvement, 2020
M. J. Higgins, C. A. Rock, R. Bouchard, B. Wengrezynek
The constructed wetland-pond system has, in series, a sedimentation basin, grass filter strip, constructed wetland, and retention pond (Figure 1) which discharges to a final vegetated polishing filter. Run-off collected and diverted from cropland first enters the sediment basin where the water is slowed and detained to allow larger particles to settle and to reduce the hydraulic impact on downstream components.
Using multispectral drones to predict water quality in a subtropical estuary
Published in Environmental Technology, 2022
Anna B. Giles, Rogger E. Correa, Isaac R. Santos, Brendan Kelaher
TSS only displayed significant correlations during March, with the NIR/Red band ratio. This contrasts with much stronger relationships for similar modelling of TSS in a sediment basin [49], and in a river system [50]. However, each study found the NIR and Red bands to be most effective for TSS estimation, despite no clear explanation for why this may be the case. We contend that this knowledge gap should be addressed in the future, for a better mechanistic understanding of how key water quality parameters reflect and absorb light. Since TSS and turbidity are often modelled remotely with satellite imagery [51], it was expected that these parameters would be consistently correlated with multispectral drone imagery in our study. The lack of correlation between TSS and more bands could be explained by greater spatial resolution of drone-based imagery compared to satellites, allowing drones to record more subtle changes in spectral readings. This sensitivity may create more noise in places where water quality has low spatial variability, and therefore weakens the relationships with homogenous parameters.
Hydrodynamics and secondary currents in an asymmetrical rectangular canal with streamwise beam
Published in Journal of Hydraulic Research, 2021
Pedro X. Sanchez, Xinqian Leng, Hubert Chanson
Although the literature on transverse rib/vane/beam is very extensive in mechanical, aeronautical, chemical, civil and environmental engineering (e.g. Adachi, 1964; Djenidi, Elavarasan, & Antonia, 1999; Knight & Macdonald, 1979; Morris, 1955), channels with longitudinal beams have been less studied, albeit the idea is not novel. Streamwise beams along channel walls have been successfully tested for the increased heat transfer rate (Chang, Lin, & Liou, 2008; Naik, Probert, & Bryden, 1999) and mass transfer in chemical engineering (Stamou, 2008). The longitudinal ribs increase the wetted perimeter and the surface contact area with the fluid. A related design was developed for biological filtration (Roo, 1965). Longitudinal beams are used in a number of stages of water treatment plants, e.g. maze flocculators, high-rate clarification tube settlers, sedimentation basins with plate settlers and sludge clarifiers (Degremont, 1979; Randtke & Horsley, 2012). In settling tank and sediment basin decant systems, longitudinal vanes are designed to minimize large-scale turbulence and to maximize the settling processes. Similar designs are also used on stormwater treatment systems and combined sewers (FNDAE, 1988). In turbulent boundary layers, longitudinal ribs and their configuration have a major impact on secondary flow motion, as well as tertiary and quaternary flows (Hwang & Lee, 2018). The existence of large secondary vortical structures is closely linked to the relative spanwise spacing of the beams (Vanderwel & Ganapathisubramani, 2015).
Laboratory investigation of performance of a screen type debris-flow countermeasure
Published in HKIE Transactions, 2018
A L Yifru, E Laache, H Norem, S Nordal, V Thakur
Rigid barriers are those countermeasures designed to fully or partially stop a debris-flow. A sabo dam with a sediment basin is a complete debris-flow stopping countermeasure that is designed according to peak debris-flow discharge and total volume [23]. The possibility of the sediment storage basin being filled during a single debris-flow event is high. Maintenance of this countermeasure requires excavation of several cubic metres of debris, which is impractical. A closed check dam is a similar kind of countermeasure but smaller in size and it only helps breaking the flow velocity while storing part of the debris-flow at its back. This type of countermeasure is usually designed and constructed sequentially along a stream to prevent bed erosion and to raise the channel bed and reduce the stream gradient [22], which can control the debris-flow energy.