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As part of a risk assessment study of the Leading Creek Watershed in Ohio, a prior Virginia Tech researcher collected pavement and subpavement sediment samples at 17 sites using the hybrid areal sampling technique with a clay adhesive. The watershed, which is heavily impacted by mining and agricultural activities, suffers from low pH, high concentrations of metals and sediment in the water column, and excessively silted streambeds. The current work presents the results of the particle size analyses performed on the hybrid samples in the context of evaluating the effectiveness of the technique itself and as a tool in future watershed/ecological studies, as well as examining possible relationships between siltation and indicators of ecological health in Leading Creek. By combining clay grid and adhesive sampling methods, the hybrid technique consistently achieved an effective particle size sampling range of 0.05 mm (1.97 x 10-3 in) to over 300 mm (11.8 in), thereby reducing the common problem of trunction. However, the overlap of the clay adhesive and natural sediment distributions and atypical sediment loading from surrounding abandoned and reclaimed mine lands obscured expected trends such as downstream fining and hindered the analysis of materials finer than 0.125 mm (4.93 x 10-3 in). Volumetric conversion of areal samples using the Modified Cube Model with a traditional exponent of -1 for clay was complicated by the large amount of fines in the Leading Creek samples. Further investigation into a more appropriate conversion technique for the evaluation of fine sediment samples is warranted. / Master of Science

Physical habitat for instream biota derives from a combination of stream system structural and hydraulic phenomena. Consequently, the quantity and quality of physical habitat is dynamic both over time and in space along the river, laterally, longitudinally and vertically. Its characterization through stream assessment and classification leads to a better understanding of factors that determine and limit habitat extent and quality. This thesis investigates the effects of space and time on nearshore aquatic habitat in the gravel reach of Fraser River, British Columbia by employing a large river, stage-adaptive habitat classification system. The distribution and abundance of habitat are spatially quantified at the reach scale (32 km), and temporally quantified through a period of about 60 years at several adjacent gravel bars (7 km), and at approximately 500 m3 s-1 increments in discharge during the declining limb of the flood hydrograph at two well-developed gravel bars. Of the ten habitat types evaluated, the bar edge habitat type is most abundant by length and number of units. However, its relative importance is reduced when weighted by fish-habitat association characteristics. Preferred habitat types (channel nook, eddy pool and open nook) are frequent and available to aquatic organisms, and most common at well-developed bars and in zones of equilibrium long-term sedimentation. Preferred habitat was at a maximum 30 years ago when major new bars developed and the thalweg shifted, effectively increasing the amount of bar shoreline and nearshore habitat. This increase is due to substantial change in river planform morphology following a 30-year period of large annual floods. However, amounts of habitat did not increase exclusively during periods of higher than average flows, or decrease exclusively during periods of lower than average flows. Instead, habitat abundance response to flow may occur with a two- or three-year lag. Short term changes in stage are critical to amount of preferred habitat. Optimal discharge for maximum preferred habitat vailability is in the range of approximately 2500 m3 s-1 to 4000 m3 s-1, which approximates long term mean flow. As flow increases, the proportion of preferred habitat compared with total bar shoreline decreases. Comparison with the 2006 flow duration curve shows that 15 – 30 % of discharges are optimal for maximum fish density and biomass. These discharges occurred during April 27 to May 17 and July 14 to August 7, 2006.

Physical habitat for instream biota derives from a combination of stream system structural and hydraulic phenomena. Consequently, the quantity and quality of physical habitat is dynamic both over time and in space along the river, laterally, longitudinally and vertically. Its characterization through stream assessment and classification leads to a better understanding of factors that determine and limit habitat extent and quality. This thesis investigates the effects of space and time on nearshore aquatic habitat in the gravel reach of Fraser River, British Columbia by employing a large river, stage-adaptive habitat classification system. The distribution and abundance of habitat are spatially quantified at the reach scale (32 km), and temporally quantified through a period of about 60 years at several adjacent gravel bars (7 km), and at approximately 500 m3 s-1 increments in discharge during the declining limb of the flood hydrograph at two well-developed gravel bars. Of the ten habitat types evaluated, the bar edge habitat type is most abundant by length and number of units. However, its relative importance is reduced when weighted by fish-habitat association characteristics. Preferred habitat types (channel nook, eddy pool and open nook) are frequent and available to aquatic organisms, and most common at well-developed bars and in zones of equilibrium long-term sedimentation. Preferred habitat was at a maximum 30 years ago when major new bars developed and the thalweg shifted, effectively increasing the amount of bar shoreline and nearshore habitat. This increase is due to substantial change in river planform morphology following a 30-year period of large annual floods. However, amounts of habitat did not increase exclusively during periods of higher than average flows, or decrease exclusively during periods of lower than average flows. Instead, habitat abundance response to flow may occur with a two- or three-year lag. Short term changes in stage are critical to amount of preferred habitat. Optimal discharge for maximum preferred habitat vailability is in the range of approximately 2500 m3 s-1 to 4000 m3 s-1, which approximates long term mean flow. As flow increases, the proportion of preferred habitat compared with total bar shoreline decreases. Comparison with the 2006 flow duration curve shows that 15 – 30 % of discharges are optimal for maximum fish density and biomass. These discharges occurred during April 27 to May 17 and July 14 to August 7, 2006.

The study which was carried out around gravel pits at Stanton Harcourt (Oxfordshire) and Rinwood (Hampshire) falls into three sections. The first involves an analysis of the groundwater character- istics of the gravels. This includes an estimation of the permeability of the gravels (using single-well dilution methods) and an analysis of the recharge mechanisms operating in them. The latter is based upon observed relationships between groundwater fluctuations and hydrometeorological factors. Secondly, the hydrological effects of gravel extraction and dewatering are analysed. By monitoring groundwater levels, the nature and extent of the zone of drav/dcvm around the gravel pits is determined. Induced recharge from rivers and recirculation of water from surface ditches into the pits, as a result of dewatering, is identified. Estimates of the proportion of induced recharge in groundwater are then made using chemical evidence. A mathematical model of gravel pit dewatering is developed. The influence of hydraulic conductivity and the initial pumping rate in determining the effects of dewatering is established by a series of sensitivity analyses using this model. As a practical example, the model is used to predict the effects of dewatering a new site near Stanton Harcourt. The extent of the drawdown around each stage in its development is determined, and this is used to evaluate the effects on private sources and agriculture in the surrounding area. Thirdly, the effects of one type of rehabilitation project (i.e. lake formation) are investigated. A method for predicting the final lake level is explained. Deviation of the observed lake levels from those predicted is explained in terms of the sealing effect of fine sediment plus chemical and biological processes. The effects of lake formation on groundwater levels and flow are described, and the changes in water quality produced by the flow of groundwater through a lake are examined.

Physical habitat for instream biota derives from a combination of stream system structural and hydraulic phenomena. Consequently, the quantity and quality of physical habitat is dynamic both over time and in space along the river, laterally, longitudinally and vertically. Its characterization through stream assessment and classification leads to a better understanding of factors that determine and limit habitat extent and quality. This thesis investigates the effects of space and time on nearshore aquatic habitat in the gravel reach of Fraser River, British Columbia by employing a large river, stage-adaptive habitat classification system. The distribution and abundance of habitat are spatially quantified at the reach scale (32 km), and temporally quantified through a period of about 60 years at several adjacent gravel bars (7 km), and at approximately 500 m3 s-1 increments in discharge during the declining limb of the flood hydrograph at two well-developed gravel bars. Of the ten habitat types evaluated, the bar edge habitat type is most abundant by length and number of units. However, its relative importance is reduced when weighted by fish-habitat association characteristics. Preferred habitat types (channel nook, eddy pool and open nook) are frequent and available to aquatic organisms, and most common at well-developed bars and in zones of equilibrium long-term sedimentation. Preferred habitat was at a maximum 30 years ago when major new bars developed and the thalweg shifted, effectively increasing the amount of bar shoreline and nearshore habitat. This increase is due to substantial change in river planform morphology following a 30-year period of large annual floods. However, amounts of habitat did not increase exclusively during periods of higher than average flows, or decrease exclusively during periods of lower than average flows. Instead, habitat abundance response to flow may occur with a two- or three-year lag. Short term changes in stage are critical to amount of preferred habitat. Optimal discharge for maximum preferred habitat vailability is in the range of approximately 2500 m3 s-1 to 4000 m3 s-1, which approximates long term mean flow. As flow increases, the proportion of preferred habitat compared with total bar shoreline decreases. Comparison with the 2006 flow duration curve shows that 15 – 30 % of discharges are optimal for maximum fish density and biomass. These discharges occurred during April 27 to May 17 and July 14 to August 7, 2006. / Arts, Faculty of / Geography, Department of / Graduate

En beräkningsmodell utvecklas för att skatta miljöpåverkan och ekonomiska effekter vid vägunderhållet grusning. Beräkningsmodellen används för att kunna jämföra alternativa metoder för grusning. Beräkningsmodellen testas genom ett testscenario med tre alternativa metoder för grusning. I alternativ ett används nytt grus och i alternativ två och tre används återvunnet grus. Studiens resultat visar att beräkningsmodellen kan användas för att skatta kostnad och miljöbelastning. Testscenariot visar att det är ekonomiskt och miljömässigt fördelaktigt att använda återvunnet grus vid grusning. Ur ett samhällsperspektiv är det viktigt att belysa fördelarna med att använda återvunnet grus, då detta kan motivera att fler faktiskt väljer detta alternativ och då brytning av naturgrus är en energikrävande process som påverkar miljön negativt. Studiens syfte är att skapa förståelse för miljömässiga och ekonomiska effekter vid återvinning av grus vid grusvägsunderhåll. För att uppnå syftet genomförs en fallstudie som besvarar frågeställningen hur miljömässiga och ekonomiska effekter kan skattas på grusvägsunderhåll. / A calculation model is developed to estimate the environmental impact and economic effects of gravel road maintenance. The purpose of the calculation model is to be able to compare alternative methods for graveling. The calculation model is tested through a test scenario with three alternative methods for graveling. In alternative one, new gravel is used and in alternatives two and three recycled gravel is used. The study's results show that the model calculation can be used to estimate cost and environmental impact. The test scenario shows that it is economically and environmentally advantageous to use recycled gravel in graveling. From a societal perspective, it is important to highlight the benefits of using recycled gravel, as this may motivate more people to actually choose this alternative. Because mining of natural gravel is an energy-intensive process that has a negative impact on the environment. The purpose of the study is to create an understanding of the environmental and economic effects of recycling of gravel during gravel road maintenance. To achieve this, a case study is conducted that answers the question how environmental and economic impacts can be estimated on gravel road maintenance.

<p> A large gravel pit at East Paris exposed 14m of Pleistocene braided outwash. Large scale longitudinal bars (30 - 400m long) were developed utilising irregular topographic highs (4 - 6m) of the basal gravels as Bar Cores. These bars prograded downstream by means of larce-scale cross-strata, periodically interupted by reactivation surfaces. Contemparaneous upstream addition of material took place by the migr ation of mixed sand and gravel bed-forms on the stoss-side of the bars. The gravel supply to the avalanche face of the major bars took the form of imbricated gravels which passed from the stoss-side, through the Bar Top, onto the Bar Front. Adjacent, sandy side-channels (4 -6m deep) exhibit a fining upward fill of trough cross beds, planar lamination and ripples; and interdigitated with the gravel bars alongside. </p> <p> Aggradation of the flood plain led to the extension of the Bar Top facies over the length of the bars, and then to the development of a Shallow-braided stream facies over the whole system. The latter is recognised by its smaller (less than 1m) bar forms composed of crossbedded gravel supplied by an imbricate gravel, and numerous small, sandy channel forms. </p> <p> At West Paris another large gravel pit exposed 6m of sandier, but stratigraphically equivalent deposits. Large scale side-bar accumulations (200-300m across) of gravel developed from river bank lateral accretion deposits. The downstream progradation was by lobes of cross-stratified and imbricated gravels, alternating with sand drapes of low flow stages. Sandy Side-channels (4m deep) developed between the gravel lobes and the accreting river bank. </p> <p> The concept of braid bar growth from a pre-existing form (bar core or river bank) is in contrast to the classic theory of development from a gravel lag. The differences may be due to depth relationships of the systems, which in this case may be the effect of position on the sandur surface. </p> / Thesis / Master of Science (MSc)

Vibratory rollers are commonly used for compaction of embankments and landfills. This task is time consuming and constitutes a significant part of most large construction and infrastructure projects. By improving the compaction efficiency, the construction industry would reduce costs and environmental impact. This research project studies the influence of the vibration frequency of the drum, which is normally a fixed roller property, and whether resonance can be utilized to improve the compaction efficiency. The influence of frequency on roller compaction has not before been studied but the concept of resonance compaction has previously been applied successfully in deep compaction of fills and natural deposits. In order to examine the influence of vibration frequency on the compaction of granular soil, small-scale compaction tests of sand were conducted under varying conditions with a vertically oscillating plate. Subsequently, full-scale tests were conducted using a vibratory soil compaction roller and a test bed of crushed gravel. The results showed that resonance can be utilized in soil compaction by vibratory rollers and plates and that the optimum compaction frequency from an energy perspective is at, or slightly above, the coupled compactor-soil resonant frequency. Since rollers operate far above resonance, the compaction frequency can be significantly reduced, resulting in a considerable reduction in fuel consumption, environmental impact and machine wear. The thesis also presents an iterative equivalent-linear method to calculate the frequency response of a vibrating foundation, such as a compacting plate or the drum of a roller. The method seems promising for predicting the resonant frequency of the roller-soil system and can be used to determine the optimum compaction frequency without site- and roller-specific measurements. / <p>QC 20160613</p>

This study focuses upon flow hydraulics, sediment transport and riffle-pool maintenance on the River Rede, Northumberland, UK. Analysis of bed structure indicate pools to be coarser than riffles, suggesting these to be zones of maximum tractive force at high flow. Tractive force reversal can be demonstrated using a combination of velocity, shear stress and gravel tracer data, and is therefore advocated as a mechanism for maintaining the riffle-pool form. Three dimensional flow structures are likely to increase the likelihood of reversal in pools situated on bends, which may not always be detected using one-dimensional measures of flow hydraulics. Magnetic tracing and basket trapping techniques were used to provide an insight into rates of movement, accumulation, initial motion criteria and routing, of sand. Sand is transported selectively and is mobilised at between 11-22 Nm⁻². Deposition of sub 2mm material is prevalent on morphological high points (bars/riffle margins), although greatest quantities were routed through morphological lows. Freeze core evidence shows limited intragravel storage. Gravel tracer movements showed evidence of size selective entrainment overall, however hiding effects were also found to be evident at two scales; 30-50mm and 110-140mm (for riffles) and 20- 90mm and 11O-140mm for pool. Slope exponents for log-log relations between scaled grain size (D/D₅₀) versus dimensionless shear stress (Өc) of ≈-0.9 suggest that hiding strongly influences sediment transport. Stream power estimates from pgQs demonstrate a higher threshold for motion for gravel in pools (132 Wm⁻²) compared with riffles (127 Wm⁻²). Differences in initial motion criteria (8e) between riffles and pools were found to be significant (p<0.05), indicating pool sediments to be less mobile than riffle, despite pool sediments being less compact. Reduced mobility of pool bedload sediment results from clasts being sheltered by immobile lag gravel found in the pool. It appears therefore that mobility differences between riffles and pools, related to bed structure, does not explain riffle-pool maintenance on the Rede. Scaled travel distance (L/L₅₀s) for tracers in the reach as a whole showed a convex-up relationship with scaled grain size (D/D₅₀s), demonstrating that for tracer grains progressively coarser than the surrounding D₅₀ surface grains, travel distance drops off rapidly, whereas grains progressively finer than the surrounding clasts, travel further but at a less rapid rate. Furthermore, virtual velocity (V*) of tracer grains showed a positive dependence upon D/D₅₀s. Gravel tracer movement provided important insights into riffle-pool maintenance. Transfer of material through the Rede riffle-pool sequence appeared to be influenced by flow magnitude and duration. For low magnitude high frequency flows below 25% bankfull, intra-unit movement was found to predominate. Medium magnitude and frequency flows (up to 50% bankfull) appeared capable of inter-unit transport; scour from pool troughs and deposition on pool exit slopes I riffle heads, movement of material from riffles to bar edges and from bar to bar. For higher magnitude low frequency flows up to bankfull, there was less scour from pools, and a dominance of bar-to-bar sediment transfer. Limited evidence of sediment routing and deposition in pools suggest these to be scour / sediment source zones only, with supply originating from the bed and outer bank. These data demonstrate the importance of different flow magnitude and frequency in creating / maintaining different areas of the riffle-pool structure.