Mean Flow and Turbulence in a Laboratory Channel with Simulated Vegatation (HES 51)

U.S. Army Corps of Engineers, Waterways Experiment Station (Contract DACW39-94-K-0010)unpublishednot peer reviewe

River Bed Response to Channel Width Variation: Theory and Experiments (HES 49)

Illinois Water Resources Center (USGS Project 04 Contract 14-08-0004-G2017unpublishednot peer reviewe

Input-variable sensitivity assessment for sediment transport relations

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

A physically-based bank erosion model for composite river banks: Application to Mackinaw River, Illinois

Meandering river migration over large spatial and temporal scales has traditionally been numerically simulated using a bank erosion submodel that calculates the eroding bank migration rate as the product of the near-bank excess flow velocity and a dimensionless migration coefficient. The latter value is an empirical parameter calibrated to historical observations. In efforts to improve upon the traditional model, recent research has followed two approaches: (a) provide a means of estimating the dimensionless migration coefficient based on field measurements; and (b) discard the traditional migration coefficient approach to develop a bank erosion submodel based on the actual formulations that dictate fluvial erosion rates and mass failure which determine bank migration. The latter physics-based approach was recently implemented into the numerical model RVR Meander developed by the Ven Te Chow Hydrosystems Laboratory at the University of Illinois in Urbana-Champaign (Motta et al, 2012a); however, the governing equations used for fluvial erosion strictly apply only to banks comprised of cohesive soils. In that formulation the fluvial erosion rate is linearly dependent on the excess boundary shear stress. This study explores whether a similarly simple formulation can describe in a gross sense the migration of river banks comprised entirely of non-cohesive soil or composite banks consisting of non-cohesive soil at the base overlain by cohesive soil. Numerical modeling of both fluvial erosion and shallow avalanche mass failures that occur simultaneously during non-cohesive bank deformation reveal that the bank migration rate is strongly non-linear with respect to the boundary shear stress (exponent greater than 1) when considering non-cohesive bank materials. A methodology is described for developing a site specific non-cohesive bank erosion submodel that is valid and computationally practicable over the desired large spatial and temporal scales relevant to models such as RVR Meander. The new methodology allows issues such as flow regime modifications to be incorporated to change the model parameters, which was not possible using the traditional empirical approach. The numerical modeling performed in this study also provides fundamental insights into deformation of non-cohesive river banks: it demonstrates that high flow events tend to cause bank slope reduction, with lower flow events tending to rejuvenate the steepness of the bank; it quantifies the importance of prior erosional history in influencing bank migration rates; and it quantifies the feedback of basal armoring on deformation of the unarmored region.U.S. Department of the InteriorU.S. Geological SurveyOpe

Characterization of critical shear stresses and bank material erosion rates on gravelly stream banks

Meandering river migration over large spatial and temporal scales has traditionally been numerically simulated using a bank erosion submodel that calculates the eroding bank migration rate as the product of the near-bank excess flow velocity and a dimensionless migration coefficient. The latter value is an empirical parameter calibrated to historical observations. In efforts to improve upon the traditional model, recent research has followed two approaches: (a) provide a means of estimating the dimensionless migration coefficient based on field measurements; and (b) discard the traditional migration coefficient approach to develop a bank erosion submodel based on the actual formulations that dictate fluvial erosion rates and mass failure which determine bank migration. The latter physics-based approach was recently implemented into the numerical model RVR Meander developed by the Ven Te Chow Hydrosystems Laboratory at the University of Illinois in Urbana-Champaign (Motta et al, 2012a); however, the governing equations used for fluvial erosion strictly apply only to banks comprised of cohesive soils. In that formulation the fluvial erosion rate is linearly dependent on the excess boundary shear stress. This study explores whether a similarly simple formulation can describe in a gross sense the migration of river banks comprised entirely of non-cohesive soil or composite banks consisting of non-cohesive soil at the base overlain by cohesive soil. Numerical modeling of both fluvial erosion and shallow avalanche mass failures that occur simultaneously during non-cohesive bank deformation reveal that the bank migration rate is strongly non-linear with respect to the boundary shear stress (exponent greater than 1) when considering non-cohesive bank materials. A methodology is described for developing a site specific non-cohesive bank erosion submodel that is valid and computationally practicable over the desired large spatial and temporal scales relevant to models such as RVR Meander. The new methodology allows issues such as flow regime modifications to be incorporated to change the model parameters, which was not possible using the traditional empirical approach. The numerical modeling performed in this study also provides fundamental insights into deformation of non-cohesive river banks: it demonstrates that high flow events tend to cause bank slope reduction, with lower flow events tending to rejuvenate the steepness of the bank; it quantifies the importance of prior erosional history in influencing bank migration rates; and it quantifies the feedback of basal armoring on deformation of the unarmored region.U.S. Department of the InteriorU.S. Geological SurveyOpe

Density currents in the Chicago River : characterization, effects on water quality, and potential sources

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Science of The Total Environment 401 (2008): 130-143, doi:10.1016/j.scitotenv.2008.04.011.Bidirectional flows in a river system can occur under stratified flow conditions and in addition to creating significant errors in discharge estimates, the upstream propagating currents are capable of transporting contaminants and affecting water quality. Detailed field observations of bidirectional flows were made in the Chicago River in Chicago, Illinois in the winter of 2005-06. Using multiple acoustic Doppler current profilers simultaneously with a water-quality profiler, the formation of upstream propagating density currents within the Chicago River both as an underflow and an overflow was observed on three occasions. Density differences driving the flow primarily arise from salinity differences between intersecting branches of the Chicago River, whereas water temperature is secondary in the creation of these currents. Deicing salts appear to be the primary source of salinity in the North Branch of the Chicago River, entering the waterway through direct runoff and effluent from a wastewater-treatment plant in a large metropolitan area primarily served by combined sewers. Water-quality assessments of the Chicago River may underestimate (or overestimate) the impairment of the river because standard water-quality monitoring practices do not account for density-driven underflows (or overflows). Chloride concentrations near the riverbed can significantly exceed concentrations at the river surface during underflows indicating that full-depth parameter profiles are necessary for accurate water-quality assessments in urban environments where application of deicing salt is common.The authors greatly appreciate the support provided by USGS, Office of Surface Water (Hydroacoustics Program), the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC), the USGS Illinois Water Science Center

Hydrologic and Hydraulic Modeling of the Tunnel and Reservoir Plan System in Northeastern Illinois

The Tunnel and Reservoir Plan (TARP) was adopted by the Metropolitan Sanitary District of Greater Chicago in 1972 to address combined sewer overflow (CSO) pollution and flooding problems in 970 km2 of the Chicago metropolitan area served by combined sewers. TARP consists of about 175 km of tunnels, three reservoirs, 256 drop shafts, and over 600 connecting structures, pumping stations, and other appurtenances for the capture and storage of CSOs and for conveying the stored CSOs to water reclamation plants for treatment. The TARP system is comprised of three independent systems: the Calumet system serving the south suburbs and a portion of the south side of Chicago, the Upper Des Plaines system serving the northwest suburbs, and the Mainstream/ Des Plaines system serving the remainder of Chicago and the north, west and southwest suburbs. The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) desires to develop new, updated and enhanced computer models to allow for simulation of the TARP systems. The new models will be used to optimize operation of the system as actually constructed, to determine constraints in the system, identify physical changes that may be needed to improve performance, and allow what-if analyses to be performed for potential storm scenarios and facility revisions. The modeling includes development of a Physical Inventory system, Hydraulic Modeling of the TARP systems, and Hydrologic Modeling of the TARP service areas. The Physical Inventory provides a digital description of the physical geometry of the TARP system and the related hydraulic performance of system components. Hydrologic Modeling uses data for each dropshafts service area to determine hydrographs describing the inflows to the TARP systems. A ma jor component of the Hydrologic Modeling is to develop tools and methods that allow robust simulation of the extreme heterogeneity of highly urbanized systems and that provide guidance for data compilation needed to improve the accuracy of such simulations. Hydraulic Modeling uses the information from the Physical Inventory and the Hydrologic Modeling to simulate hydraulic response of the TARP system to different inputs. The Hydraulic Modeling tools developed are capable of simulating the range of possible flows in the system, from gravity flows over a dry bed to mixed gravity/surcharged flows to shocks and hydraulic transients

Time resolved emission spectroscopy of poly(2,5-dicyano-p-phenylene-vinylene) films

Films of poly (2,5-dicyano-p-phenylene vinylene), DCNPPV, were obtained by electrochemical synthesis over gold thin layer (20 nm) transparent electrode deposited on a glass plate. The DCNPPV films of 4 µm thickness were produced by electropolymerization process of α,α,α',α'-tetrabromo-2-5-dicyano-p-xilene at different applied potentials (-0.15, -0.25, -0.40, -0.60, -0.80, and -1.0 V) using 0.1 mol L-1 of tetraethylammonium bromide in acetonitrile as the supporting electrolyte. The emission decays have three exponential components: a fast component in the picosecond range (200-400 ps), and two other of about one and five nanoseconds at 293 K. The fluorescence quenching process seems to occur by exciton trapping in a low-energy site and quenching by residual bromine monomer attached at the end of the polymer chain. However, the electrochemical synthesis generates entrapped bromide or ion pairs during the growth step of the film which also contributes to the deactivation. The change of the electrolyte from bromide to perchlorate reduces significantly this additional quenching effect by allowing ion exchange of formed bromide with the nonquenching perchloride anion.Filmes finos de poli(2,5-diciano-p-fenileno vinileno), DCNPPV, foram produzidos por síntese eletroquímica com variação do potencial aplicado de-0,15 até-1,0 V, e depositados sobre camada fina de ouro sobre vidro. A cinética de estado excitado destes materiais foi investigada por medidas de decaimentos de fluorescência. Os filmes apresentam decaimentos com três componentes, uma rápida da ordem de 200-400 picossegundos, e outra duas componentes de aproximadamente um e cinco nanossegundos, na temperatura de 293 K. O decaimento de fluorescência ocorre pela desativação em sítios de baixa energia na cadeia polimérica conjugada e por supressão do estado excitado por monômeros bromados terminais da cadeia e íons brometo aprisionados durante o crescimento eletroquímico do filme. A mudança do ânion do eletrólito suporte de brometo para perclorato reduziu de modo significativo essa contribuição de supressão do estado excitado como resultado da troca iônica por uma espécie não supressora.FAPESPCNP

Review of Methodologies to Assess Bridge Safety During and After Floods

This report summarizes a review of technologies used to monitor bridge scour with an emphasis on techniques appropriate for testing during and immediately after design flood conditions. The goal of this study is to identify potential technologies and strategies for Illinois Department of Transportation that may be used to enhance the reliability of bridge safety monitoring during floods from local to state levels. The research team conducted a literature review of technologies that have been explored by state departments of transportation (DOTs) and national agencies as well as state-of-the-art technologies that have not been extensively employed by DOTs. This review included informational interviews with representatives from DOTs and relevant industry organizations. Recommendations include considering (1) acquisition of tethered kneeboard or surf ski-mounted single-beam sonars for rapid deployment by local agencies, (2) acquisition of remote-controlled vessels mounted with single-beam and side-scan sonars for statewide deployment, (3) development of large-scale particle image velocimetry systems using remote-controlled drones for stream velocity and direction measurement during floods, (4) physical modeling to develop Illinois-specific hydrodynamic loading coefficients for Illinois bridges during flood conditions, and (5) development of holistic risk-based bridge assessment tools that incorporate structural, geotechnical, hydraulic, and scour measurements to provide rapid feedback for bridge closure decisions.IDOT-R27-SP50Ope