Riverbed Research Articles

The effect of seasonal variation, flow conditions and erosion forces on suspended matter fluxes from boreal gypsum-treated agricultural fields

Like many other bodies of water, the Baltic Sea is facing a severe eutrophication problem, the excessive nutrient load currently originating primarily from agriculture. Gypsum treatment has shown promising results in reducing phosphorus and suspended sediment loads, especially in fine-textured soils, but its efficacy has not been investigated on catchment scale to any wide extent. This study examines the functionality of the gypsum treatment in an agriculture-dominated boreal catchment in the Archipelago Sea basin. The relation between turbidity and hydro-climatological factors was analysed during different years and seasons and the effect of stream erosion during different flow stages was investigated by applying 2D hydraulic modeling. A special focus was given to deviating winter conditions and freeze-thaw cycles.The results highlight the dependency of stream water turbidity on the discharge and the potential negative impact of the climate change-altered winter conditions of the hemiboreal climate zone on gypsum treatment effectiveness. The turbidity increased even more during high winter discharges, compared to other seasons suggesting that the more frequent freeze-thaw cycles and precipitation coming as rain during the unvegetated period increase erosion challenging the gypsum efficacy. Modelling results revealed that the increased erosional power during very high discharges caused settled material resuspension or stream bed or bank erosion leading to a cumulative increase in turbidity at downstream, an issue needing further research. Demonstrating the real and long-term effects of nutrient reduction measures requires catchment scale investigations over years, considering climatological factors. Based on this study, local and short-term investigations can potentially lead to over-simplified interpretations.

Changes in physicochemical parameters of the alpine/mountain stream influenced by summer flash flood in Tatra Mountains (Western Carpathians)

taChanges to the physicochemical parameters of water in alpine/mountain streams can provide evidence of ongoing natural and anthropogenic processes in their catchment. In this study, we analysed a mountain stream (Javorinka) on the north-eastern side of the Tatra Mountains (Western Carpathians), which is minimally influenced by human activity. The stream was monitored weekly for 5 years (2017–2021) and evaluated for its seasonal variations in physicochemical parameters. These seasonal variations were influenced by the large summer flash flood in July 2018. We hypothesise that floods are essential for the oligotrophic profile of alpine/mountain streams. To support this idea, our main objective was to compare the seasonal trends of the main physicochemical parameters in the stream before and after floods or periods of high flow. We found evidence to support our hypothesis. For example, there was a significant decrease in the chemical consumption of oxygen and ammonia, and, conversely, an increase in the ratio of saturated oxygen and nitrate concentrations. Stream bed erosion also resulted in increased phosphates (over the next 2 years) and high enrichment of the water by dissolved solids in the spring. Interestingly outside of the main objectives, we observed a significant decrease in sulphates, especially in the summer and autumn of 2020 and 2021, which may be related to suppressed emissions due to the restriction of the COVID-19 lockdown. The observed trends and their changes therefore support the idea that alpine/mountain streams are excellent indicators of ongoing environmental processes, and that occasional summer flash floods support the oligotrophic profile of the stream system.

Vertical riverbed deformations due to in-stream mining

Comparison of the longitudinal profile of a number of lowland rivers in Russia, revealed their deformation due to a half-century of sediment flux and channel morphology adjustment. This problem remains relevant both in theoretical and practical aspects, especially for rivers where long-term mining of sediments from the stream beds extends from kilometers to tens of kilometers. The removal of a large amount of alluvial material from the sediments transport and changes of the riverbed morphometric characteristics triggered the process of leveling the sediment transport capacity along the river by the scour and resulted in a lowering of the bottom and water surface. The intensity of the incision reached 3–8 centimeters, and its progradation along the river 400–700 meters per year. Retrogressive erosion is pronounced, while progressive one is less pronounced, because partially replaced by mechanical removal of alluvial material. Over the past decades the shape of the longitudinal profiles changed from convex or straight to concave with no signs of recovery, despite the mining has been quite moderate for last 30 years or completed on the explored rivers.

Біорізноманіття гідрологічного заказника «Луга» у межах міста Володимир (Волинська область)

According to the results of the research, it was established that the flora of vascular plantsof the Luga River is 119 species, the faunal complex is represented by 80 species of animals ofthe mammal class – 3 species, birds – 23 species, amphibians – 2 species, fish rays – 6 species,earthworms –1 species, crustaceans – 2 species, arachnids – 2 species, insects – 28 species,molluscs – 12 species. The following families are the most numerous in terms of the number ofgenera and speciesAsteraceae, Poaceae, Lamiaceae, Apiaceae, Brassicaceae, Polygonaceae,Rosaceae. It is these families that have the greatest floristic diversity and occupy a leading placein the study area, and their spectrum is evidence of a strong anthropogenic influence on thevegetation cover.Various biotopes have formed in the floodplain of the Luga River and along its periphery,which differ in structure and varying degrees of transformation. The plant species composition ofthe floodplain of the Luga River is represented by typical aquatic, coastal-aquatic macrophytesand mesophytic forbs of floodplain meadows. The largest areas are occupied by monodominantgroups of Phragmites australis and Glyceria maxima, in smaller measures Typha latifolia. Theanimal world of the Luga River and its floodplain is represented by 16 species of hydrobiontsand 13 species of amphibiotic animals. Mammalia – 1 species, Aves – 6 species, Amphibia – 2species, Actinopterygii – 6 species, Crustacea – 1 species, Insecta – 6 species, Bivalvia – 2species, Gastropoda – 6 species.The marginal biotopes of the terraces are characterized by the dominance of ruderalcommunities with a significant participation of adventive plant species. The rarity component ofthe flora is represented by rare groups of yellow pitcher plants (Nuphareta luteae). Intensiveprocesses of natural overgrowth of the Luga River bed have been noted, which causes the flow toslow down, silt to accumulate, and the species composition of plants and animals to change. Thestudy area is characterized by high phytocenotic activity Аcer negиndo, Echinocуstis lobata,Solidago canadensis, Heracleum sosnowskyi, Heracleum mantegazzianumm etc. The animalworld of the edge terraces is represented by 64 species of animals. Mammalia – 3 species, Aves– 20 species, Amphibia – 2 species, Crustacea – 1 species, Arachnida – 2 species, Insecta – 28species, Gastropoda – 4 species.The main trends and threats caused by the anthropogenic factor have been identified:increased recreational load and accompanying degradation of vegetation due to direct impact onareas of mass gathering of vacationers, which leads to the disappearance of typical coastal-waterspecies of plants and animals associated with them, transformation as a result of anthropogeniceutrophication, which leads to a change in the structure of macrophyte and hydrobiontcommunities. The transformation of plant cover and animal complexes takes place in thedirection of replacing natural species with apophytes and adventitious plant species,synanthropic animal species and plant pests that are more resistant to anthropogenic influence.

Role of manganese oxides and oxyhydroxides in phosphate sequestration in natural aquatic environments

Excessive inputs of phosphorus (P) to aquatic environments can lead to eutrophication. Adsorption of phosphate on Fe oxides is one of the main process that can limit P availability. Oxidized forms of Mn have also been suggested to play a role in P trapping. However, although a considerable number of studies have shown the relationships between the geochemistry of Fe and that of phosphates, few studies have attempted to show the direct links between Mn and P. In the present study, we studied the adsorption of phosphate on synthetized Mn(III) and Mn(IV) oxides placed under natural conditions. The aim was to compare the role of Fe and Mn oxides in phosphate adsorption. Two muddy sediments were collected in a river bed at the edge of a large agricultural area. A sandy sediment was collected downstream. A muddy and a sandy sample were taken in a coastal environment. The experiments on phosphate adsorption by sediment and Mn oxides were carried out in slurries containing in situ waters spiked with 10 μM phosphate. Control experiments without Mn-oxide addition showed that the natural sediments tested still had the capacity to adsorb phosphate, in particular due to the presence of reactive Fe(III) oxides, extractable by an ascorbate solution. The addition of Mn(III) and Mn(IV) oxides in much larger quantities than the initial quantity of Fe oxides had little impact on the rate of phosphate adsorption. For both Mn(III) and Mn(IV) oxides, the Mn/P ratio between added particulate Mn and adsorbed P was very high, with values between 260 and 1000. The Fe/P ratio of the iron oxides contained in the slurries was between 6 and 20. On average, the P adsorption capacity of the Fe oxides was 50 times greater than that of the Mn oxides. Manganese oxides are generally less abundant than iron oxides in natural environments. Mn oxides therefore play a minor role in P sequestration compared with Fe oxides. Even if there are environments where Mn oxides can concentrate, the reduction of Mn oxides and subsequent liberation of adsorbed P does not represent a major risk for eutrophication of aquatic ecosystems.

Eco-friendly Boost of the Subgrade: Coconut Shell Ash and River Bed Shell Ash

Eco-friendly Boost of the Subgrade: Coconut Shell Ash and River Bed Shell Ash

წყალდიდობის პროგნოზირების საკითხისათვის

. Global climate change has caused sharp increasing of natural calamities, including floods. In the course of recent period, over the entire world, every year there are occurring tens of cases of disastrous floods and waterflows characterized by damages worth of several millions and human losses. The issue of forecasting waterflows and floods, in general, is discussed in the article. There are given basic differentiating features-characteristics existing between spring floods and rain-caused waterflows. The methodology of forecasting related decision-making based on the Statistical Fuzzy Analysis is developed at Ivane Javakhishvili Tbilisi State University, which methodology can be used for flood forecasting. The methodology consists of two stages. At the first stage one and the same prognostic event is assessed using three methods, which allow to make independent forecast. At the second stage, according to the mentioned forecast, the final decision is made. The factors suggested for application of this methodology for flood forecasting are directly related to the climatic parameters of the territory and the state of a river bed and lower terrace. The basic goal of the methodology suggested for flood forecasting is timely reporting on an anticipated disaster.

Мохоподібні парку-пам’ятки садово-паркового мистецтва місцевого значення «Снопківський» (м. Львів)

The species diversity and substratum preferencies of Bryophytes in the territory of the local park-monument park “Snopkivsky” in the urban ecosystem of Lviv are given in the article. The bryoflora of the Snopkivsky Park includes 61 species of bryophytes from the divisions Marchantiophyta and Bryophyta. The high position of the families Brachytheciaceae, Orthotricaceae, Pottiaceae, Bryaceae in the floristic spectrum reflects the specificity of the park’s local conditions. The percentage of these families in the floristic spectrum is 45.9 % of the total species richness. This distribution is characteristic of aridic natural zones, which indicates the dry condition of the urban microclimate. At the same time, a good representation of the boreal and nemoral forest families such as Mniaceae, Amblystegiaceae, Hypnaceae (21.3 % of the total species richness) reflects the natural features of the territory (the zone of broad-leaved forests), which spontaneously reproduced on part of the Park territory or were created artificially in ornamental gardening. In this part of the Park with spontaneous silvatisation the largest number of bryophyte species is concentrated and the moss cover is the most abundant. Poor representation of Marchantiophytes indicates a significant degree of anthropization of the studied urban ecosystem. There is an increase in the number of anthropogenic ecotopes in the Park, which is reflected in a significant upgrowth in the fraction of epilithic bryophyte species. Ravines and abandoned quarries have the greatest conservation value for mosses on the Park territory. Some anthropophobic species as components of epigeic, epiphytic and epixylic substrates groups, which are not characteristic of intensively urbanized areas, are occur here. No rare bryophyte species were found within the park. However, floating liverwort Riccia fluitans, which is not typical for urban areas in general, was found in the Zelene Oko lake. Calcareous tufa deposited in the bed of hard-water streams at the headwaters of the Snopkivsky stream is a specific habitat for bryophytes. Indicators for hard-water springs with tufa formation of European lowland arias bryophytes species (Apopellia endiviifolia, Cratoneuron filicinum and Platyhypnidium riparoides) were found here. Amphibious (primarily calciphilic tufa-forming) and free-floating bryophyte species are equally not typical for urbanized ecosystems and occur here only sporadically: this fact underlines the conservation value of the researched park for the pre­servation of bryophytes microhabitats within the city boundaries. The conservation of silvatic areas, both spontaneous and artificial, is an important condition for the effective functioning of the park as a semi-natural ecosystem. The diversity of bryophytes, their species composition and cover abundance are indicative of the integrity of urban ecosystems on the territory of the park “Snopkivsky”.

Conservation equations for open-channel flow: effects of bed roughness and secondary currents

AbstractTime-averaged velocity fields in uniform open-channel flows over rough beds may exhibit spatial heterogeneities due to the effects of bed roughness and secondary currents (SCs). The latter typically originate from the turbulence anisotropy and spatial heterogeneity introduced by the solid and mixed corners (i.e., between sidewalls and water surface), but may also appear due to roughness spanwise heterogeneities, e.g., associated with patchy vegetation distributions or streamwise sediment ridges on the channel bed. In this paper, we propose rigorous conservation equations for momentum, kinetic energy and fluid stresses accounting for the contributions of bed roughness and SCs, separately. Particular attention is given to the terms regulating the energy exchanges between roughness-induced and SC-related motions, which are expected to provide information on the physical mechanisms leading to the generation of roughness-induced SCs. The proposed approach is illustrated using a large-eddy simulation of a rough-bed open-channel flow.

Geomorphic Response to the Removal of the Ward's Mill Dam on the Watauga River, North Carolina

abstract: Though economic situations of individual dams vary, current dam removal studies largely indicate that ecological benefits of river re-connectivity may outweigh the costs of maintaining aging infrastructure. However, there is a lack of comprehensive studies in certain regions of the United States, including Southern Appalachia. We used the removal of the 6-meter-high Ward's Mill Dam on the Watauga River in North Carolina to conduct a before-after/control-impact study to monitor geomorphic impacts to such removals in this understudied region with the objective of identifying changes in channel form, analyzing bed sediment characteristics, and quantifying rates of volumetric evacuation and deposition. To capture geomorphic change repeated pre- and post-removal cross-sectional surveys, longitudinal profiles, and in-situ particle size sampling was conducted in upstream and downstream reaches. Field collections the day after removal show significant deposition of gravel sized particles immediately downstream of the dam (≤200 m). Channel bed texture remains significantly finer across the 2 km downstream study reach 506 days following removal. Erosion rates of the impoundment during the deconstruction period were on average ~860 m3/day and decreased to 75.5 m3/day by day 74. Below average mean daily flows during this period were able to exhume ~62.9 percent of impounded sediment.

Stage–discharge prediction in the multi-stage ice-covered compound channel

The multi-stage compound channel, which is a common pattern in natural alluvial rivers and the regulation projects of urban rivers, inevitably freezes in winter when it is situated in cold northern areas with high latitudes. Given that ascertaining the stage–discharge relationship for rivers is the foundation for the development of flood control schemes and water resources management, this study concentrates on proposing an analytical model for predicting the stage–discharge curves of multi-stage ice-covered compound channels. In deducing the analytical model, the cross section of the channel is first segmented into several homogeneous subregions that can be grouped into seven categories according to the geometric characteristics. Through analyzing the momentum transfer between adjacent subregions, the force balance equation for each subregion is then established to get the bulk mean velocity for the corresponding subregion, thereby obtaining the discharge by solving a tridiagonal matrix. Subsequently, measurements from two-stage and three-stage ice-covered compound channel experiments and three sets of experimental data from the literature are used to validate the performance of the proposed model. Good agreement between the predictions and the measured data suggests that the deduced model can accurately estimate the discharge for the multi-stage ice-covered compound channels when the flow depth is given. Finally, sensitivity analysis indicates that Manning's roughness coefficient of the channel bed has a more pronounced impact on the stage–discharge relationship than that of the ice cover. Moreover, when compared to the two-stage ice-covered compound channel, the multi-stage ice-covered compound channel offers greater potential for water resource utilization.

A Research Report Comprising on Behaviour of Sea Sand and Normal Sand

Abstract: Consumption of concrete has grown rapidly over a year, and it is also becoming one of the basic constructionmaterials. Since, it is a composite mixture of the constituents containing cement, fine aggregate, coarse aggregate and water. For manufacturing the concrete the fine aggregate are required more quantity. In general, river sand and RIVDER SAND is used as fine aggregate in construction industry. Due to this increase in use of river sand and RIVDER SAND the requirement has been increasing massively day by day in building sector. The government also have given some limitation on mining of river sand from the river beds. The treatment needed to remove the salt content in sea sand and sea water is difficult on time oftreatment and cost. So, the untreated sea sand is used in this test. The work on this study evaluates the different comparisons of mechanical properties of complete RIVDER SAND , complete sea sand (SS) and50% of RIVDER SAND with 50% of sea sand (MSSS). Main intention to consider the sea sand based concrete is to preserve the environmental resource in economical and sustainable development in construction and concrete sector. The experimental test results of sea sand based concrete shows adverse increase in strength compared to RIVDER SAND based concrete specimens

Evaluation of the microbial wet-vacuum system (M-Vac®) for DNA sampling from rough, porous substrates, and its compatibility with fully automated platforms

DNA retrieval methods traditionally used during forensic evidence recovery including swabbing and tape lifting, can have limited effectiveness when used on porous, rough substrates such as bricks and carpet. This is possibly due to the DNA material being dispersed and unreachable for surface sampling techniques. In this evaluation we investigated the effectiveness of the Microbial Wet-Vacuum System (M-Vac®; M-Vac® Systems, Inc., Sandy, UT), as it has been reported to retrieve greater amounts of DNA material from challenging exhibits. A four-stage evaluation was conducted, starting with seeding carpet and brick substrates with a known donor’s saliva in two dilutions and comparing the DNA recovery of tape lifting, swabbing, and the M-Vac®. A victim struggle scenario on carpet was then mimicked to compare trace DNA recovery by each method. Two mock scenarios were also conducted; a shirt was submerged in a creek bed for a period of five days to sample for the wearer’s DNA, and a car boot was sampled to assess the possibility of recovering a victim’s DNA amongst background DNA from the usual car occupants. Finally, the compatibility of the M-Vac® sampling process was optimised for the fully automated DNA lysis and extraction platforms used in the NSW (Australia) jurisdiction by comparing filter subsampling methods. The results from the study were mixed. For bricks, none of the collection methods were effective in retrieving DNA. On carpet, the M-Vac® retrieved the greatest quantities of DNA from the saliva-seeded samples, however, tape lifts outperformed all methods for ‘touch’ DNA recovery. The M-Vac® retrieved the greatest amount of DNA from the t-shirt recovered from a creek bed as it was able to retrieve the embedded DNA. The final mock case car boot scenario resulted in greater victim DNA recovery from tape lifts, with the M-Vac® more likely to recover mixtures too weak and/or complex to be interpreted. Finally, operational considerations regarding the compatibility of the M-Vac® system with fully automated DNA lysis and extraction are discussed. Considering the substantial time and cost to deploy the M-Vac®, it is recommended to be utilised in casework only after swabbing and tape lifting methods have failed to yield sufficient DNA material, where the substrate properties would likely benefit from the M-Vac’s® niche capabilities for retrieving embedded DNA, and low levels of background DNA may be anticipated.

Countermeasure of Protection Against Local Scouring Downstream of Concrete Check Dams

Check dams are planned to control sediment and gravel runoff during floods. In accordance with the planning for the Sabo works, check dams have been constructed in each watershed, which may reduce serious sediment transport during floods. On the other hand, as the ratio of the installation of check dams to the planning is proceeded, sediment transport is limited, and degradation of the riverbed has been observed downstream of check dams. In general, localized scouring was observed downstream of the sub-dam even after protection blocks were installed downstream of the check dam. This may be caused by the lack of functionality to raise the main flow in the protection blocks. In concrete check dams, there are different types of ordinary closed check dams and check dams silted at a center part of dam. In terms of countermeasures against local scouring downstream of the sub-dam, there is no difference of design method for different types of check dams. Recently, the ramp with consecutively assembled boulders was proposed by Yasuda, the installation of the ramp below low drop structure is effective for both protection of river bed during flood stages and migration of multi-aquatic animals for normal stages. This paper presents that the installation of the ramp with consecutively assembled boulders downstream of a sub-dam is effective for different types of check dams. Experimental results show that the thee-dimensional main flow through the sub-dam can be controlled by the formation of seepage flow in the ramp composed by the assembled boulders, and that the main flow always rises toward the water surface at the downstream end of the ramp. The cross section of the ramp has a parabolic shape, and the velocity near the sidewall can be reduced in comparison with the center part of the ramp during flood stages. In addition, the migration for the multi-aquatic animals on the ramp is possible during normal stages as in the case of low drop structure.

Turbulent kinetic energy budget of sediment-laden open-channel flows: bedload-induced wall-roughness similarity

New experiments in highly turbulent, steady, subcritical and uniform water open-channel flows have been carried out to measure the mean turbulent kinetic energy (TKE) budget of sediment-laden boundary layer flows with two sizes (dp = 3 mm and 1 mm) of Plexiglas particles $({\rm relative\ density}\ = 1.192)$ . The experiments covered energetic sediment transport conditions (Shields number of $0.35 < \theta < 1.2$ ) ranging from non-capacity to full-capacity flows in bedload-to-suspension-dominated transport modes (suspension number of $0.5 < {w_s}/{u_\ast } < 1.3$ where ${w_s}$ is the settling velocity and $u_*$ is the friction velocity) and for weakly to highly inertial, finite size turbulence-particle conditions (Stokes number of 0.1 < St < 3.5 and dp/η > 10 where $\eta$ is the Kolmogorov length scale). It was shown that the effects of sediments on the TKE budget are very pronounced in all large particle experiments for which a bedload layer of several grain diameter thickness is developed above the channel bed. When compared with the corresponding reference clear-water flows, the TKE shear-production rate for the 3 mm particle flows is strongly reduced in the wall region corresponding to the bedload layer. This turbulence damping is seen to increase with sediment load until full capacity for flows with constant Shields value, as well as with Shields number value. Inside this damped TKE shear-production zone, a distinct peak of maximal turbulence production appears to coincide with the upper edge of the bedload layer delimited by a sharp gradient in mean sediment concentration. This vertically upshifted peak of TKE production is accompanied by an enhanced net downward oriented TKE flux when compared with the reference clear-water flows. The downward diffused TKE is found to act in the bedload layer as a local energy source in reasonable balance with the sediment transport term. The mechanism behind this downward TKE transport was further analysed on the basis of coherent flow structure dynamics controlled by ejection- and sweep-type events. The agreement between the height of downward directed mean TKE flux and the height below which sweep-type events dominate the Reynolds shear-stress contribution over ejections, revealed the leading role played by sweeps in mean TKE transport. This agreement holds for all reference clear-water flows supporting the well-known wall-roughness-induced dominance of the sweep contribution in turbulent, rough clear-water boundary layer flows. Furthermore, for all 3 mm particle flows, the two referred to transition levels were significantly and similarly upshifted to the upper edge of the bedload layer. Only for these sediment-laden flows, the bedload layer thickness is seen to exceed the wall-roughness sublayer of the reference clear-water flows. This supports a strong analogy between wall-roughness effects in clear-water flows and bedload layer effects in sediment-laden flows, on the mean TKE budget induced by a similarly modified coherent flow structure dynamics. The bedload layer-controlled wall roughness is finally confirmed by the good prediction of the wall-roughness parameter ks of the logarithmic velocity distribution. An empirical formulation fitting the presented measurements is presented, valid over the range of Shields number values covered herein.

Debris‐flow entrainment modelling under climate change: Considering antecedent moisture conditions along the flow path

AbstractDebris‐flow volumes can increase along their flow path by entraining sediment stored in the channel bed and banks, thus also increasing hazard potential. Theoretical considerations, laboratory experiments and field investigations all indicate that the saturation conditions of the sediment along the flow path can greatly influence the amount of sediment entrained. However, this process is usually not considered for practical applications. This study aims to close this gap by combining runout and hydrological models into a predictive framework that is calibrated and tested using unique observations of sediment erosion and debris‐flow properties available at a Swiss debris‐flow observation station (Illgraben). To this end, hourly water input to the erodible channel is predicted using a simple, process‐based hydrological model, and the resulting water saturation level in the upper sediment layer of the channel is modelled based on a Hortonian infiltration concept. Debris‐flow entrainment is then predicted using the RAMMS debris‐flow runout model. We find a strong correlation between the modelled saturation level of the sediment on the flow path and the channel‐bed erodibility for single‐surge debris‐flow events with distinct fronts, indicating that the modelled water content is a good predictor for erosion simulated in RAMMS. Debris‐flow properties with more complex flow behaviour (e.g., multiple surges or roll waves) are not as well predicted using this procedure, indicating that more physically complete models are necessary. Finally, we demonstrate how this modelling framework can be used for climate change impact assessment and show that earlier snowmelt may shift the peak of the debris‐flow season to earlier in the year. Our novel modelling framework provides a plausible approach to reproduce saturation‐dependent entrainment and thus better constrain event volumes for current and future hazard assessment.

Sediment control and flow redistribution with submerged vanes: a review

ABSTRACT The most challenging issues in rivers include sediment management, outer bank erosion, intake choking, channel bed shoaling, and river meandering. This paper provides a concise review of the newly developed sediment and flow control technique known as the Iowa vane or submerged vane. Submerged vanes are small flow training structures designed to redistribute flow and sediment within the channel cross-section. The structural stability and economic feasibility of submerged vanes, which distinguish them from conventional methods such as dikes and groins, have inspired many researchers to study their use and efficiency in river management over many decades. Various hydrodynamic characteristics, such as flow structure, sediment motion, vortex generation, and scouring around submerged vanes and arrays of vanes, have been reviewed. Additionally, various vane parameters that influence these characteristics are also explained. This paper also underscores current limitations in understanding the flow and sediment behavior around submerged vanes, while also providing recommendations for future research in the field.

Effect of emergent vegetation on riverbank erosion with sediment mining

The present work investigates the combined effects of the upstream sediment mining pit and vegetation on the riverbank using emergent rigid vegetation beyond the toe on the flow structure and morphological changes due to fluvial erosion. A steep gradient of streamwise velocity and other turbulence parameters such as Reynolds shear stress (RSS), transverse RSS, and turbulent kinetic energy (TKE) at the interface of the vegetated and unvegetated part of the test segment was observed. The cross-sectional analysis showed that vegetation increased the velocity of the unvegetated main channel, and the sandpit increased even the near-bed velocity with a similar trend in its longitudinal variation at the center line of the main channel. The abrupt variation in RSS and transverse RSS at the location of the berm induces instability and erodes the berm present at the toe of the riverbank. The combination of the vegetation and sandpit led to increased TKE of the flow at the near-bed and berm locations. The morphological analysis showed complete riverbank erosion in both cases of the unvegetated riverbank, i.e., without or with an upstream pit. The installed stems of rigid vegetation on the riverbank helped decrease the fluvial erosion of the riverbank, and its profile observed minimal changes over the length of the test segment. However, the main channel erosion was amplified due to the vegetation (in no-pit case) at the beginning of the test segment, which eroded the bed of the main channel by about 67% of the bed thickness. Also, in the vegetated riverbank cases, the upstream pit caused an increase in erosion by 7.66% at the center of the main channel. The study helps establish the hypothesis of negating the effects of sediment mining on bank erosion by using the rigid vegetation on the riverbank beyond its toe location, which performed well by maintaining the riverbank profile.

Experimental Investigations on Mineral Admixtures and Steel Fibers in High Strength Concrete

In the process of manufacturing of concrete sand is the most commonly used fine aggregate. The main sources for the natural sand are river beds. These characteristic assets are getting depleted because of over abuse and defilement by chemicals and waste from nearby industries. The waste generated from the demolition of existing structures for various reasons causes great concern and ecological issues. In this project our main objective is to study the influence of partial replacement of F.A with recycled fine aggregate and to compare it with the compressive strength and workability of high strength M60 concrete. We are also trying to replace the various percentages of recycled fine aggregate to study the tendency of the Characteristic strength of concrete.

Evaluating opportunities for broad-scale remote sensing of total suspended solids on small rivers

Although broad-scale remote sensing applications are increasingly being integrated into water quality assessments, the feasibility of such applications on smaller rivers (<150 m. width) is not well understood, even though smaller rivers comprise most of the river network and can constitute significant sources of sediment and nutrients. We evaluated the application of a widely used Total Suspended Solid (TSS) algorithm within ten small (16–117 m wide) tributaries of the Lake Champlain Basin in the Northeastern US. Sentinel-2 images captured within 5 h of depth-integrated TSS samples were identified and corrected for atmospheric conditions to generate TSS estimates. Linkages between sample attributes and errors in the relationship between measured and predicted TSS values were explored to identify potential limits on the application of existing TSS algorithms to small rivers. From a dataset of 64 unique measured-predicted values on rivers whose channel width was greater than one pixel (i.e., 10 m), we found that there are settings along smaller rivers, and discrete flow and seasonal conditions, under which broad-scale remote sensing applications may be applicable. The remote sensing algorithm had the greatest success predicting TSS for rivers with high background levels of sediment (i.e., large concentrations during smaller discharges). Errors in estimated TSS were three times greater on rivers with low background levels (average error of 174%) of sediment than high levels (average error of 57%), likely due to differences in the proportion of fine-grained particle-sizes in transport. We also found that estimated TSS error was less outside the growing season, when biological activity was limited and plants were dormant, and when higher flows occurred such that backscatter from the channel bed is less likely to interfere with the reflective signal. This effect was most pronounced on rivers with low background sediment loads; errors in estimated TSS were more than six times greater during the growing season on rivers with low background loads (average error of 216%) than when plants were dormant (average error of 48%). We hypothesized that algorithm performance on smaller rivers, as measured by channel width, would be prone to larger errors due to the greater influence of contrasting reflectance signals from soils and vegetation along riverbanks. The degree of limitation from this adjacency effect was not evident in our dataset perhaps because of a correlation between river size and sediment characteristics unique to our study area. An alternative parameterization of a single-band empirical TSS model for small rivers in the region, based on inclusion of readily identifiable geologic and temporal characteristics, suggests improved predictive power for small rivers. Results highlight the feasibility of extending remote sensing applications throughout the river network in temperate regions of the Northeastern U.S. Certain geologic settings, specifically those that transport finer-grained loads, are more likely to have accurate predictions, especially during the colder months, when in situ monitoring is particularly challenging, yet highly important because a significant portion of runoff events in the Northeastern U.S. occur in this time.