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In the past decade, continuously rising water levels in Lake Michigan have been threatening lakefront areas, especially in metropolitan regions like the Greater Chicago area. This provides the motivation to analyze the impact that high lake levels have on the Chicago Area Waterway System (CAWS). As the only primary free connection between the CAWS and Lake Michigan, the Calumet Area waterway subsystem plays a key and unique role. In this work, a numerical model covering the Calumet subsystem and having Lake Michigan as a boundary condition, is set up, calibrated, and validated using limited field observations. It is found that the Calumet subsystem has become bidirectional, where both discharge and flow directions are controlled by lake levels. When lake levels are below −0.15 m (-0.5 ft, Chicago City Datum, CCD), the discharge in the Grand Calumet River is around zero, with water flowing along its east branch towards Indiana. When lake levels are above +0.46 m (+1.5 ft, CCD), the flow reverses direction and drains west into Illinois. In 2020, the mean lake-level was at +1.07 m (+3.5 ft, CCD), and the base discharge in the Grand Calumet River was approximately 8.5 m3/s (300 ft3/s). The higher Lake Michigan’s level is, the larger the discharge would be into Illinois. Potential impact of this extra discharge on Lake Michigan Diversion Accounting (LMDA) of the State of Illinois and flood management in the Chicago Sanitary and Ship Canal (CSSC), is analyzed; while the nature of the bidirectional flows is characterized with the intent of shedding light on this complex phenomenon.

Wind power generation faces intermittency challenges, typically requiring reserve power sources to maintain reliability of the electricity grid. This study proposes that hydropower turbines installed at low-head dams can provide reserve power generation to support wind power, avoiding the externalities associated with fossil-fuel plants and conventional hydropower. Low-head dams in the United States are used for flood control, securing municipal water supplies, and providing reservoir pools for recreation. As a case study, we estimated hydropower potential at 12 low-head dams along a 150-km reach of the Fox River (Northeastern Illinois, USA) using a calibrated river flow model. We analyzed the model's output to assess power generation capacity and reliability as a source of baseload power and as a component in a coupled wind-hydropower system. The modeled system performed reliably over a five-year time period despite significant long-term fluctuations in streamflow, offsetting the short-term variability of wind power. However, combining the low-head hydropower system with wind power limited the output of the system to the minimum generated by the low-head hydropower. The low-head hydropower system's small capacity and high break-even price suggest that it is better suited for local applications rather than grid-scale operations, especially if permitting regulations are considered.

A well-balanced and positivity-preserving meshless method based on smoothed particle hydrodynamics (SPH) is developed to simulate one-dimensional (1D) and two-dimensional (2D) shallow water (SW) fl...

Travertine deposits preserved within ancient aqueduct channels record information about the hydrology, temperature, and chemistry of the flowing water from which they precipitated. However, travertine is also chemically reactive and susceptible to freshwater diagenesis, which can alter its original composition and impact reconstructions of aqueduct operation, maintenance, and climate. Hydraulic reconstructions, in combination with a suite of high-resolution optical, laser, electron, and X-ray microscopy analyses, have been used to determine the original crystalline structure and diagenetic alteration of travertine deposited in the Anio Novus aqueduct built in A.D. 38–52 at Roma Vecchia. Age-equivalent travertine deposits, precipitated directly on the mortar-covered floor at upstream and downstream sites along a 140-m-long continuous section of the Anio Novus channel, exhibit consistent crystalline textures and stratigraphic layering. This includes aggrading, prograding, and retrograding sets of travertine linguoid, sinuous, and hummocky crystal growth ripples, as well as sand lags with coated siliciclastic grains deposited on the lee slope of ripple crests. The original aqueduct travertine, which is similar to travertine formed in analogous natural environments, is composed of shrub-like, dendritically branching aggregates of 1–3-μm-diameter euhedral calcite crystals. Dark brown organic matter-rich laminae, formed by microbial biofilms and plant debris, create stratigraphic sequences of high-frequency, dark–light layering. This hydraulic and petrographic evidence suggests that large, radiaxial calcites diagenetically replaced the original aqueduct travertine shrubs, forming upward-branching replacement crystals that crosscut the biofilm laminae. While this diagenetic process destroyed the original crystalline fabric of the calcite shrubs, the entombed biofilm laminae were mimetically preserved. These integrated approaches create the type of depositional and diagenetic framework required for future chemostratigraphic analyses of travertine deposited in the Anio Novus and other ancient water conveyance and storage systems around the world, from which ancient human activity and climatic change can be more accurately reconstructed.

We present an experimental analysis of hydraulic roughness variations due to changes in alluvial cover in a mixed bedrock-alluvial meandering channel with larger bedrock roughness than alluvial rou...

The oceanic seabed contains a variety of mineral resources related exclusively to submarine environments. Limited information has been documented for the seabed offshore of Chile, which is particularly interesting due to its geodynamic context and large area. Mineralogical and geochemical analyses of 16 sites within the Chiloé–Taitao area, from 83 to 3388 m in depth, were carried out. The most abundant minerals are quartz, feldspars, pyroxenes, amphiboles, epidote, and biotite, with lower quantities of zircon, white mica, olivine, pyrite, magnetite, ilmenite, and hematite. Framboidal pyrites are mainly present at &gt, 900 m depth, and could be associated with methane hydrates, which have been reported in the area and its surroundings. Tenorite, sphalerite, tennantite, cordierite, birnessite, and tellurobismuthite were revealed by XRD analysis at low concentrations but at many sites. Birnessite, a Fe–Mn nodule-forming mineral, was widely detected, and Pearson correlations showed elemental associations related to the presence of Mn oxides. Samples did not evidence Fe–Mn nodules, probably due to the redox and depth conditions. Nonetheless, it is probable that to the west, polymetallic nodules are present in deeper zones. In the southern part of the area, reflective grains were identified, with up to 58.3 wt.% Cu, these grains might be derived from the continent or formed by in situ diagenetic precipitation.

Bubbly Creek is the historical name given to the West Fork of the South Branch of the Chicago River (SBCR). Even though its base flow is small, during extreme storm events Bubbly Creek beco...

A substantial body of research has addressed the equilibrium cross-sectional geometry of straight noncohesive channels, along with bends having fixed outer banks. However, development of a characte...

Direct numerical simulations of oscillatory boundary-layer flows in the transitional regime were performed to explain discrepancies in the literature regarding the phase difference is the angular velocity based on the period of the oscillation T). Variations of the mean velocity slope and intersect values for oscillatory flows are also explained in terms of the proximity to near-equilibrium conditions. Relaminarization and transition effects can significantly delay the development of OBL flows, resulting in an incomplete transition. The shape and defect factors are examined as diagnostic parameters for conditions that allow the formation of a logarithmic profile with the universal von Karman constant and intersect. These findings are of relevance for environmental fluid mechanics and coastal morphodynamics/engineering applications.

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Depth-averaged two-dimensional (2D) models are useful tools for understanding river morphodynamics through the computation of hydrodynamics, sediment transport, and an evolving river bed morphology. This paper presents a new parallelized 2D hydrodynamic, sediment transport, and bed morphology model, HydroSedFoam. The model uses the Message Passing Interface for code parallelization and adopts a depth-averaged k − e turbulence model. Three different case studies, including a laboratory experiment, an analytical solution, and a field-scale river reach, show good agreement with HydroSedFoam simulations. Further development and modification of the model are relatively straightforward to accomplish within the OpenFOAM framework.

The complexity of open channel confluences stems from flow mixing, secondary circulation, post-confluence flow separation, contraction and backwater effects. These effects in turn result in a large number of parameters required to adequately quantify the junction induced hydraulic resistance and describe mean flow pattern and turbulent flow structures due to flow merging. The recent development in computing power advances the application of 3D Computational Fluid Dynamics (CFD) codes to visualize and understand the Confluence Hydrodynamic Zone (CHZ). Nevertheless, 1D approaches remain the mainstay in large drainage network or waterway system modeling considering computational efficiency and data availability. This paper presents (i) a modified 1D nonlinear dynamic model; (ii) a fully 3D non-hydrostatic, Reynolds-averaged Navier–Stokes Equations (RANS)-based, Computational Fluid Dynamics (CFD) model; (iii) an analysis of changing confluence hydrodynamics and 3D turbulent flow structure under various controls; (iv) a comparison of flow features (i.e. upstream water depths, energy losses and post-confluence contraction) predicted by 1D and 3D models; and (v) parameterization of 3D flow characteristics in 1D modeling through the computation of correction coefficients associated with contraction, energy and momentum. The present comprehensive 3D numerical investigation highlights the driving mechanisms for junction induced energy losses. Moreover, the comparative 1D and 3D study quantifies the deviation of 1D approximations and associated underlying assumptions from the ‘true’ resultant flow field. The study may also shed light on improving the accuracy of the 1D large network modeling through the parameterization of the complex 3D feature of the flow field and correction of interior boundary conditions at junctions of larger angles and/or with substantial lateral inflows. Moreover, the enclosed numerical investigations may enhance the understanding of the primary mechanisms contributing to hydraulic structure induced turbulent flow behavior and increased hydraulic resistance.

En la actualidad los sistemas de automatización industrial deben optimizar las técnicas de control y comunicación de sus procesos, para introducir conceptos dados por la Industria 4.0. Para lograr esto se necesita de la introducción de nuevas normas de automatización para obtener sistemas de fabricación ágiles e inteligentes, es por esto que la norma IEC 61499 es considerada como la opción principal. Industria 4.0 en unión con IEC 61499 permitirá la integración de sistemas de adquisición de datos tradicionales y novedosos sistemas de procesamiento inteligente de datos, con el objetivo de extraer información y mejorar el rendimiento general del sistema productivo. El presente trabajo establece un enfoque de arquitectura flexible para el diseño de los Diagramas de Control de Ejecución de los Bloques de Función basado en la norma ISA 88 aplicado a un proceso industrial, lo que permitirá implementar el control industrial bajo IEC 61499 de manera eficiente y rápida permitiendo un diseño se software basado en componentes con independencia de la plataforma hardware usada.

Transport of oil through pipelines is at an all-time high and so is the risk of oil spill accidents. The July 2010 spill of diluted bitumen into the Kalamazoo River was the largest release of heavy crude into an inland waterway in the history of United States. After extensive cleanup and recovery efforts, substantial residual deposits from the oil spill remained in the river system, mainly due to the formation of oil–particle aggregates (OPAs). Understanding the conditions under which OPAs can be suspended, transported and deposited is important for river management. Concerns about OPAs reaching Lake Michigan motivated this work. A three-dimensional Eulerian/Lagrangian model for OPA transport was developed for Morrow Lake in the Kalamazoo River, using specified OPA properties based on laboratory experiments. The three-dimensional model included the Morrow Lake dam operational rules as well as wind effects, which might increase the risk of resuspension and transport of OPA downstream. The usage of the model as a management tool is illustrated; the suitability of the model framework to incorporate the more complex processes of OPA formation transformation is discussed.

Many earlier developed and densely populated metropolises served by combined sewer systems have been implementing additional stormwater control measures to reduce the impacts of combined sewer overflows (CSO) driven by severe rainstorms. These mitigation measures call for robust modeling strategies to assess the overall performance before development and to predict vulnerabilities, and examine the underlying mechanisms causing them during or after development in a systematic manner. This paper first introduces a hydrologic and hydraulic coupled modeling program-MetroFlow that interacts and integrates multiple models built via diverse methods and tools. A typical integrated urban drainage system (IUDS) in the greater land area of Chicago in the US was investigated as a testbed. In addition, a large-scale Tunnel and Reservoir Plan in construction was evaluated as a mitigation measure to alleviate CSO risks. In this effort, three models were coupled into MetroFlow to account for the best available data of the multiple structural layers involved in this evolving system. Hydrological responses were analyzed under existing and projected system conveyance and storage capacities considering the full spectrum of rainfall conditions employing synthetic storms and real-time simulations of four historical extreme events to account for the anomalies exemplified by individual natural events. The overall effectiveness and resilience of the system were further assessed by the evaluation of normalized performance indicators (PIs) quantifying the reduction of total volume, duration and spread of CSOs. The cluster of simulation results collectively suggests that: (a) the proposed structural layer-based modeling approach is applicable in reproducing distributed rainstorm-driven CSOs for an evolving IUDS based on emerging digital-physical data; (b) CSO characteristics are rather multivariate functions of the rainfall tempo-spatial characteristics as well as the hydraulic performance of the collection system and (c) consistent improvement of CSO abatement was predicted with increasing conveyance and storage provided by the deep tunnel system. The projected system is predicted to capture 24-h storms of return period up to 10 years. MetroFlow’s framework may also promote collaborative modeling, in which community-scale models can be utilized and merged to support extended-scale water and wastewater infrastructure planning, design and management.

A methodology to assess input-variable sensitivity for sediment transport relations is presented. The Mean Value First Order Second Moment Method (MVFOSM) is applied to two bed load transport equations showing that it may be used to rank all input variables in terms of how their specific variance affects the overall variance of the sediment transport estimation. In sites where data are scarce or nonexistent, the results obtained may be used to (i) determine what variables would have the largest impact when estimating sediment loads in the absence of field observations and (ii) design field campaigns to specifically measure those variables for which a given transport equation is most sensitive; in sites where data are readily available, the results would allow quantifying the effect that the variance associated with each input variable has on the variance of the sediment transport estimates. An application of the method to two transport relations using data from a tropical mountain river in Costa Rica is implemented to exemplify the potential of the method in places where input data are limited. Results are compared against Monte Carlo simulations to assess the reliability of the method and validate its results. For both of the sediment transport relations used in the sensitivity analysis, accurate knowledge of sediment size was found to have more impact on sediment transport predictions than precise knowledge of other input variables such as channel slope and flow discharge.

Bulle-Effect is a phenomenon in which a disproportionately higher amount of near-bed sediment load at a fluvial diversion moves into the diverted channel, even for cases in which the proportion of water (with respect to the main flow) entering the diversion channel is relatively small. This phenomenon has wide ranging implications for both engineered and natural systems; from efficient design of channels to redirect water and sediment for reclaiming sinking deltas, designing navigational channels that do not need frequent dredging, to morphological evolution of river bifurcations. The first ever, and one of the most extensive set of experiments conducted to explore this phenomenon, were conducted by Bulle in 1926. In the current study the experiments conducted by Bulle have been simulated using an open-source, free-surface finite-element based hydrodynamic solver. Main objectives were to explore to what extent the complex phenomenon of Bulle-Effect at the scale of a laboratory experiment can be simulated accurately using Reynolds-Averaged Navier-Stokes (RANS) based hydrodynamic solver, and to understand the details of the hydrodynamics that Bulle could not analyze through his experiments. The hydrodynamics captured by the simulations were found to match the observations made by Bulle through his experiments, and the distributions of sediment at the diversion predicted by the numerical simulations were found to match the general trend observed in the laboratory experiments. The results from the numerical simulations were also compared with existing one-dimensional models for sediment distribution at bifurcations, and the three-dimensional numerical model was found to perform appreciably better. This is expected due to the complex flow features at the diversion, which can only be captured satisfactorily using a three-dimensional hydrodynamic model.

This paper explores the length scales and statistical characteristics of form roughness along the outer banks of two elongate bends on a large meandering river through investigation of topographic variability of the bank face. The analysis also examines how roughness varies over the vertical height of the banks and when the banks are exposed subaerially and inundated during flood stage. Detailed data on the topography of the outer banks were obtained subaerially using terrestrial LiDAR during low flow conditions and subaqueously using multibeam echo sounding (MBES) during near-bankfull conditions. The contributions of various length scales of topographic irregularity to roughness for subaerial conditions were evaluated for different elevation contours on the bank faces using Hilbert-Huang Transform (HHT) spectral analysis. Statistical characteristics for discrete areas on the bank faces were determined by calculating the root-mean-square of normal distances from a TIN surface. Results of the HHT analysis show that the characteristics of roughness along bank faces composed primarily of non-cohesive sediment, and eroding into cropland, vary with bank elevation and exhibit a dominant range of roughness length scales (~15-50 m). On the other hand, bank faces composed predominantly of cohesive material and carved into a forested floodplain have relatively uniform topographic roughness characteristics over the vertical extent of the bank face and do not exhibit a dominant roughness length scale or range of length scales. Additionally, comparison between local surface roughness for subaerial versus subaqueous conditions shows that roughness decreases considerably when the banks are submerged, most likely because of the removal of vegetation and eradication of small-scale erosional features in non-cohesive bank materials by flow along the bank face. Thus, roughness appears to be linked to the hydraulic conditions affecting the bank, at least relative to conditions that develop when banks are exposed subaerially.

Mineral exploration of prospective areas concealed by extensive post-mineralization cover is growing, being very complex and expensive. The projection of rich and giant Paleocene to early Oligocene porphyry-Cu-Mo belts in northernmost Chilean Andes (17.5–19.5°S) has major exploration potential, but only a few minor deposits have been reported to date, due to the fact that the area is largely covered by post-mineral strata. We integrate the Cenozoic stratigraphic, structural and metallogenic evolution of this sector, in order to identify the most promising regions related to lesser post-mineral cover and the projection of different metallogenic belts. The Paleocene to early Eocene metallogenic belt extends along the Precordillera, with ca. 30 km wide, and includes porphyry-Cu prospects and small Cu (±Mo-Au-Ag) vein and breccia-pipe deposits. Geochronological data indicate an age of 55.5 Ma for an intrusion related to one deposit and ages from 69.5 to 54.5 Ma for hydrothermal alteration in one porphyry-Cu prospect and largest known Cu deposits. The middle Eocene to early Oligocene porphyry belt, in the Western Cordillera farther east, is associated with 46–44 Ma intrusions. It is estimated to be 40-km wide, but is largely concealed by thick post-mineral cover. The youngest Miocene to early Pliocene metallogenic belt, also in the Western Cordillera, is well-exposed and includes Au-Ag epithermal and polymetallic veins and manto-type deposits. The Oligocene-Holocene cover consists of a succession of continental sedimentary and volcanic rocks that overall increase in thickness from 0 to 5000 m, from west to east. These strata are subhorizontal in the west and folded-faulted towards the east. Miocene gentle anticlines and monocline flexures extend along strike for 30–60 km in the Precordillera and were generated by propagation of high-angle east-dipping blind reverse faults with at least 300–900 m of Oligocene bedrock offset. The thickness of cover exceeds 2000 m in the eastern Central Depression, whereas it is generally less than 1000 m in the Precordillera along the Paleocene to early Eocene porphyry-Cu belt and it can reach locally up to 5000 m in the Western Cordillera, above the middle Eocene to early Oligocene belt. In the studied Andean segment, the Miocene to early Pliocene metallogenic belt is superimposed on the Paleocene to Oligocene belts in a 40–50 km wide zone. This overlap may be explained by an accentuated migration of the magmatic front, from east to west, since ca. 25 Ma, as a consequence of subduction slab steepening after a period of magmatic lull and flat subduction from ca. 30–35 to 25 Ma. The identified areas of lesser cover thickness are prone to exploration for concealed deposits, especially along the projection of major porphyry-Cu-Mo belts.

Combined sewer overflow (CSO) can be a critical inflow source for urban rivers during storm events. This paper presents a case study of the Chicago waterway. A three-dimensional (3D) river hydrodynamic model was developed and integrated with an urban rainfall-runoff model using the Open Modelling Interface (OpenMI). Both the effects of CSO discharge on river and river water levels on CSO outlets were considered by the integrated model. A historical storm, which was similar to a 100-year return period rain event, was simulated and compared with field measurements. This study highlights the necessity of quantifying CSO for hydraulic modelling of urban rivers under extreme storm event conditions, and shows that an integrated hydrologic and hydraulic approach can be used to address this challenge. The 3D river hydrodynamic model can deal with the complex hydrodynamics at river confluences and provide better hydrodynamic results for water quality modelling in the future.

Until now, only one Cenozoic fossil mammal from the Chilean Precordillera (Arica and Parinacota Region) has been reported, Caraguatypotherium munozi (Mesotheriidae: Notoungulata). In this study, we describe a fourth specimen of C. munozi and a new armadillo species, Epipeltephilus caraguensis (Peltephilidae: Cingulata), both collected from a new site closer to the fossiliferous outcrops of the Caragua area (Serravallian – Tortonian). E. caraguensis differs from other members of the family in having: two sulci in the articular surface of the mobile osteoderm; having a tubular, rough and raised anterior edge; a conspicuous transverse depression; and four widely spaced foramina. This taxon represents the youngest known peltephilid from intermediate latitudes and indicates a wide geographic distribution (Patagonia to Central Andes) of the family just prior to its extinction. The new mesothere specimen is 19% larger than previous records. The revision of the dental features of C. munozi allowed the identification of an ambiguous trait in its original diagnosis, i.e. an enamel fracture was misinterpreted with the presence of a posterior sulcus on the talonid of the m3, suggesting that further taxonomic and systematic revision for the Caragua mesothere is necessary. Although the fossil record from the Caragua area is still scarce, mesotheriines seem to be abundant at this latitude, just as has been observed at several early to late Miocene sites such as Chucal (Chile), Cerdas and Nazareno (Bolivia), as well as in southern regions such as Arroyo Chasico and Mendoza (Argentina). The presence of a new peltephilid species in Caragua sustains the hypothesis of provincialism during the Miocene in intermediate latitudes. Our findings also provide further support for probable faunal movements between intermediate and higher latitudes rather than to lower ones.

This paper evaluates conveyance and flow characteristics for the Anio Novus, the aqueduct bringing water from the greatest distance to ancient Rome. Travertine accumulations, deposited from water on floor and walls, were used to reconstruct the flow rate and associated spatial and temporal variations. Hydraulic quantities (e.g., flow depth and velocity) markedly varied over the course of the aqueduct, implying that constraints such as topography and construction techniques were combined with hydraulic considerations to determine the aqueduct layout. Design practices differed along the aqueduct and channel size design was not based exclusively on anticipated carrying capacity, tending towards larger-than-necessary design based on experience.

Pool-riffle sequences play a central role in providing habitat diversity conditions both in terms of flow and substrate in gravel bed streams. Understanding their capacity to self-maintain has been the focus of research for many years, starting with the velocity reversal hypothesis. This hypothesis relied only on cross sectional averaged flow information, but its limited success prompted extensions of the hypothesis and alternative explanations for self-maintenance. Significant advances beyond the velocity reversal hypothesis have been achieved by incorporating more information either on flow or sediment transport characteristics. However, this has been done in a compartmentalised way, with studies either focusing on one or the other aspect. This work bridges the gap between these two aspects by using an approximate methodology that combines observed characteristic stage-dependent 3-D flow patterns with time-varying cross sectional information on bed shear stresses, sediment distribution and sediment bed changes during a one-year record of continuous discharges from a real stream. This methodology allows us to track the behaviour of different sediment size fractions along flow streamlines over time and identify self-maintenance conditions due to the combined effect of both flow multi-dimensionality and sediment transport. We apply this approximate methodology to two contiguous pools and riffles and demonstrate that, unexpectedly, they may rely on different mechanisms for self-maintenance due to differences in geometry and sediment size distribution. We also demonstrate that our methodology is potentially overarching and integrative of previous partial approaches based on flow multidimensionality or sediment transport, which tend to underestimate the occurrence of self-maintenance. This article is protected by copyright. All rights reserved.

The seabed included in the Chilean Exclusive Economic Zone (EEZ) has proper conditions to originate and host different ore deposits, but its geological knowledge is scarce and scattered. The existent studies are very limited in terms of geochemical and mineralogical analyses. The most significant non-energetic mineral resources off Chile correspond to Fe-Mn nodules and crusts, phosphorite deposits, gold and titanium placer deposits and massive sulfide deposits. Fe-Mn nodule sites occur in abyssal plains and seamounts, and around volcanic islands, at depths from 2,890 to 4,332 m, and can contain important concentrations of Cu and Ni (up to 1.38% Cu+Ni) and Co (up to 0.53%). Co-rich Fe-Mn crust occurrences have been reported around the Rapanui and Salas y Gómez islands, with Cu+Ni contents up to 0.3%. Phosphorite sites occur in Holocene sedimentary beds of the continental shelf off Peru and northern Chile, with P2O5 average content of 22.6%. Gold placer deposits are found in beaches and channels of southern Chile and may extend offshore probably in submarine canyons. Titanium placer deposits have been evaluated in different beaches of Chile and could also be continued offshore. Platinum anomalies have been found in channels and bays of southernmost Chile. No samples of Volcanogenic Massive Sulfide (VMS) mineralization are known in the Chilean EEZ to date. However, samples of hydrothermal vents, with potential for polymetallic VMS type mineralization, have been recovered around the Rapanui Island, and several seamount and volcanic island chains indicate favorable conditions for formation and preservation of these ore-deposits. The available geological information on the seabed of the Chilean EEZ is insufficient to estimate the real potential of its non-energetic mineral resources.

The most common bedload transport calculation methods use an equation for the vector direction that is a linear function of the transverse slope. Existing theoretical formulations that acco...

Meandering is one of the unique processes in Earth surface dynamics. Since the 1960s, fluvial geomorphologists have generalized numerous widely-acknowledged empirical or semi-empirical formulae to describe meandering rivers' characteristics. The most frequently applied one is the Kinoshita high-sinuosity curve to describe meander channel planform geometry. Combining the Kinoshita curve with the Beck equations to describe the riverbed topography at equilibrium state, a prototype of a synthetic riverbed topography generating model is made for idealized meandering rivers. Such a method can be readily extended and applied to arbitrary meandering rivers in the real world, resulting in the synthetic riverbed topography model, pyRiverBed, presented herein. A meander migration and neck cutoff submodel is also embedded in pyRiverBed. Unlike existing linear and non-linear bend theory-based models, pyRiverbed aims towards generating the riverbed topography for each snapshot during the migration process. The present model can facilitate meandering river researchers to interpolate their field-measured bathymetric data using the synthetic bed, design their non-flat bed laboratory flumes for experiments, and initialize their hydrodynamic and morphodynamic numerical models. It can also provide guidance in stream restoration projects on designing a channel with a morphodynamic equilibrium bed. The quality of generated synthetic bed topography is evaluated through the comparison against both laboratory experiment data and field-measured data. The meander migration submodel is validated using a real-world channel migration and neck cutoff event. The validation results prove that the synthetic riverbed's accuracy is reasonably good, and the meander migration submodel can successfully predict meander migration and neck cutoff.

Point bars are prominent features in meandering rivers, yet our understanding of the complex interactions among the morphology of the point bars to channel planform and curvature remains incomplete. This study seeks to address the extent to which channel centerline curvature can explain point bar morphology. High-resolution elevation datasets obtained from multibeam sonar and structure-from-motion surveys are used to characterize point bar morphology on twelve point bars within two river systems; the Pearl and Wabash rivers. Spatial series of centerline curvature are compared to channel and point bar characteristics including width, migration rate, centerline longitudinal bed elevation, transverse bed slope, and a shape factor. Results show that the Wabash reach has overall lower channel curvature values and higher rates of migration compared to the Pearl reach. However, the spatial lag between curvature and width and migration rate are similar between reaches. The mode of bend migration differs between the two reaches, where the Pearl reach has bends mostly evolving through translation downstream, and along the Wabash reach, one bend is expanding, two bends are mostly stationary, and three bends are translating downstream. The translating bends in both reaches exhibit bilinear (a pronounced break in slope) and near-horizontal (a pronounced break in slope with a nearly flat bar top) transverse bar profiles and maximum rates of migration downstream of the apex. The Pearl reach has a systematic distribution of transverse bar profiles where linear profiles are found along the bar head and bar tail, and near-horizontal profiles are concentrated along the middle bar. The distribution along the bars of the Wabash reach is less systematic, with fewer near-horizontal profiles overall. Finally, to evaluate the influence of curvature on the channel bed and bar morphology, the field data are compared to synthetic bed elevation data generated using pyRiverBed, a centerline curvature-driven bed evolution model that maintains a constant width. Analyses reveal the synthetic morphologic data agree reasonably well with the characteristics and magnitude of the field observations, with a mean absolute error of 0.9 and 1.2 m for the Pearl and Wabash rivers, respectively. Values of transverse slope were also compared between the field and synthetic data and the synthetic data are consistently under-predicted along the Pearl. Differences observed between the field and synthetic data are the result of variability in the natural river system not captured by the model including channel width, the presence of local bedrock outcrops, and abrupt changes in curvature.

The erosion of rock-bedded channels generally is considered a slow process caused mainly by abrasion due to bedload or suspended sediments, but the mechanisms of rapid erosion remain unclear. Cavitation is a clear-fluid erosive process, well known for its effect on engineering structures, when water vapour bubbles collapse and the resultant pressure shocks erode the boundary. However, although the occurrence of cavitation erosion in natural watercourses has long been a matter of debate, as yet there are no incontrovertible examples of cavitation damage to natural river beds. Using flume experiments, we show for the first time that only weakly-cavitating clear-water flows can occur for the range of flow velocities observed in rivers, and these do not erode medium-hardness rocks after 68 hours. During this time period, only a very soft rock featured erosional marks due to dissolution. Thus, our results cast significant doubt on the likelihood of identifying cavitation damage in most rivers, and provide pointers to those river systems that might be investigated further to identify cavitation erosion. Copyright © 2016 John Wiley & Sons, Ltd.

Understanding the conveyance of sewer networks is vital, especially in cases of great variability in flow rates, such as in combined sanitary and storm sewer systems. Conventional conveyance studies in sewer systems often have extended computation times due to complexity of the solution, or alternatively make assumptions that ignore the water-surface profile within a pipe. In previous research, the hydraulic performance graph (HPG) was successfully used for open-channel capacity determination. The HPG summarizes the results of many backwater calculations for a reach so that these calculations do not need to be repeated. This article describes algorithms utilized by the Illinois Conveyance Analysis Program that uses the HPGs to describe the conveyance of a system, identify bottlenecks for varying conditions, conserve mass by tracking outflow and overflows under stepwise steady flow conditions. The software is freely available at https://github.com/obergshavefun/icap/wiki.

We used a numerical model to analyze the impact of combined sewer overflows (CSOs) in the hydrodynamics and water quality of the Chicago Area Waterway System (CAWS). We coupled the Environmental Fluid Dynamics Code (EFDC) with the Water Quality Analysis Simulation Program (WASP) to perform three-dimensional simulations of the hydrodynamics and water quality in CAWS. The analysis was performed for two different storms: (i) May 6, 2009 representing a 6-hour duration 4-month return period, and (ii) September 12, 2008 representing a 48-hour duration 100-year return period. Results from the simulations show distinct differences between the two storms. During the May 2009 storm there was only one major CSO pumping event with negligible impact on the water quality of CAWS. During the September 2008 storm there were several CSOs that impacted the hydrodynamics and water quality of CAWS. In particular, CSOs during the September 2008 event induced a reversal flow in CAWS, with a plume of constituents that traveled in the opposite direction as water does under normal conditions. However, the simulation results show that CSOs events in CAWS take place during periods of high rainfall, thus the discharge of CSOs is significantly diluted along the CAWS. As a result, the concentrations of organic matter and inorganic nutrients observed at the downstream boundary in CAWS were significantly lower than those recorded at the CSOs outfalls and are within the limits established in the regulation for regular effluents. These results suggest that even during storms events with significant CSOs into the CAWS there is a significant dilution that reduce the impact in the water quality at the system boundaries.

Few studies have examined the three-dimensional flow structure and bed morphology within elongate loops of large meandering channels. The present study focuses on the spatial patterns of three-dimensional flow structure and bed morphology within two elongate meander loops and examines how differences in outer bank roughness influence near-bank flow characteristics. Three-dimensional velocities were measured during two different events – a near-bankfull flow and an overbank event. Detailed data on channel bathymetry and bedform geometry were obtained during a near-bankfull event. Flow structure within the loops is characterized by strong topographic steering by the point bar, by the development of helical motion associated with flow curvature, and by acceleration of flow where bedrock is exposed along the outer bank. Near-bank velocities during the overbank event are less than those for the near-bankfull flow, highlighting the strong influence of the point bar on redistribution of mass and momentum of the flow at sub-bankfull stages. Multiple outer bank pools are evident within the elongate meander loop with low outer bank roughness, but are not present in the loop with high outer bank roughness, which may reflect the influence of abundant large woody debris on near-bank velocity characteristics. The positions of pools within both loops can be linked to spatial variations in planform curvature. The findings indicate that flow structure and bed morphology in these large elongate loops is similar to that in small elongate loops, but differs somewhat from flow structure and bed morphology reported for experimental elongate loops. This article is protected by copyright. All rights reserved.

We have developed a probabilistic model to simulate the fate and transport of nonconservative constituents in urban watersheds. The approach implemented here extends previous studies that rely on the geomorphological instantaneous unit hydrograph concept to include nonconservative constituents. This is implemented with a factor χ that affects the transfer functions and therefore accounts for the loss (gain) of mass associated with the constituent as it travels through the watershed. Using this framework, we developed an analytical solution for the dynamics of dissolved oxygen (DO) and biochemical oxygen demand (BOD) in urban networks based on the Streeter and Phelps model. This model breaks down the catchment into a discreet number of possible flow paths through the system, requiring less data and implementation effort than well-established deterministic models. Application of the model to one sewer catchment in the Chicago area with available BOD information proved its ability to predict the BOD concentration observed in the measurements. In addition, comparison of the model with a calibrated Storm Water Management Model (SWMM) of another sewer catchment from the Chicago area showed that the model predicted the BOD concentration as well as the widely accepted SWMM. The developed model proved to be a suitable alternative to simulate the fate and transport of constituents in urban catchments with limited and uncertain input data.

The unsteady flow characteristics around two partially buried objects, a short cylinder and a truncated cone, were examined with a three-dimensional, non-hydrostatic hydrodynamic model under similar steady unidirectional currents with flow Reynolds numbers, Re, of 86,061 and 76,209, respectively. Model simulations were conducted with the two objects partially buried in a simulated rippled river bed. A Reynolds-averaged Navier–Stokes (RANS) equation model coupled with a κ-ε turbulence closure was used to validate the experimental velocity measurements. A large eddy simulation (LES) turbulence model was subsequently used to characterize the unsteady flow structure around the objects. The LES closure allowed for the characterization of highly unsteady coherent turbulent structures such as the horse-shoe vortex, the arch-shaped vortex, as well as vortex shedding in the wake of the object.

In December 2009, during a piscicide treatment targeting the invasive Asian carp in the Chicago Sanitary and Ship Canal, Rhodamine WT dye was released to track and document the transport and dispersion of the piscicide. In this study, two modeling approaches are presented to reproduce the advection and dispersion of the dye tracer (and piscicide), a one-dimensional analytical solution and a three-dimensional numerical model. The two approaches were compared with field measurements of concentration and their applicability is discussed. Acoustic Doppler current profiler measurements were used to estimate the longitudinal dispersion coefficients at ten cross sections, which were taken as reference for calibrating the longitudinal dispersion coefficient in the one-dimensional analytical solution. While the analytical solution is fast, relatively simple, and can fairly accurately predict the core of the observed concentration time series at points downstream, it does not capture the tail of the breakthrough curves. These tails are well reproduced by the three-dimensional model, because it accounts for the effects of dead zones and a power plant which withdraws nearly 80 % of the water from the canal for cooling purposes before returning it back to the canal.

Laboratory experiments were performed to quantify the near-wall flow characteristics and the bed shear stress in the vicinity of an axial-flow rotor model. It was placed in a smooth-wall open channel flow under subcritical conditions and operated at two heights. A laser Doppler velocimeter was used to collect profiles of the streamwise and vertical velocity at few locations within the rotor symmetry plane as close as one wall unit from the bed. Local estimates of the mean bed shear stress were obtained from the mean velocity profiles in the viscous and logarithmic regions. Results show that the bed shear stress is sensitive to the distance from the rotor and to the relative height of the rotor. Maximum bed shear stress occurred downstream of the rotor with the rotor closer to the bed. Flow statistics shows a reduction of turbulence intensity and turbulent shear stress near the wall and close to the rotor due to flow acceleration and changes in the pressure distribution. Spectral analysis of the streamwise velocity evidences a reduction of the energy content across scales spanning two decades right below the turbine. The increase of bed shear is due to mainly flow accelerating but not to turbulence.

This is an Accepted Manuscript of an article published by Taylor & Francis Group in [Journal of hydraulic research] on [2016], available online at: http://www.tandfonline.com/10.1080/00221686.2016.1174960 We investigate coherent structures present in oscillatory boundary layers over smooth and rough beds for Reynolds numbers between 103 and 104, in the transition to turbulence regime. A two-camera 2D- particle image velocimetry (PIV) system was used to visualize coherent structures in an oscillatory-flow tunnel. The obtained results show that smooth-bed flow is populated by vortex-tube structures that are formed due to the Kelvin–Helmholtz instability. Three types of coherent structures are observed in the rough-wall experiments: vortices randomly distributed in space; turbulent bursts – spatial structures without a clear shape compared to vortices but with a longer life than the former; and shear layers of vortices originating due to flow separation from some of the grains on the bed. The reported study contributes to the description of coherent structures in oscillatory flows that are captured with the PIV technique, particularly a new structure in flows over rough beds in the transition to turbulence regime.

With rapidly growing urbanization, urban flooding and water quality control are becoming a vital component of sustainable urban infrastructure. Integrated urban hydrologic and hydraulic modelling represents a potential framework for capturing system interactivity and optimizing the design, operation, and engineering of urban systems. This work describes how a widely-used hydrodynamic model, the Environmental Fluid Dynamics Code (EFDC), was made compliant with the Open Modelling Interface (OpenMI) standard. The new version of the EFDC has potential to be coupled with any OpenMI-compliant model for various studies. As an example, this paper presents an application of the OpenMI version of EFDC coupled with InfoWorks-CS for a representative highly urbanized area in the city of Chicago, Illinois, United States. The integrated modelling simulates the two-way linkage between the sewer network and the Chicago Area Waterway System (CAWS). This interaction between the river and sewer pipe systems can not be described by decoupled models. By coupling the models, it is possible to observe the interaction between the sewer system overflow discharge and the hydraulic head in the pipe network. This is particularly important since higher water levels in the pipe system increase the potential for flooding. Display Omitted

Laboratory experiments suggest a larger Shields parameter value requirement to initiate motion on permeable beds than on impermeable ones, which is connected with the lower lift force on a permeable bed.

Coastal, estuarine, fluvial and submarine morphodynamics encompass some of the leading processes shaping our planet. They stem mainly, but not only, from the interaction of water in motion and movable sediment boundaries, resulting in morphological changes produced by erosion, transport and deposition of sediments that generate a variety of landsca