Sediment Entrainment Functions for Navigation-induced Resuspension
M. H. García,* J. Rodriguez, D. Admiraal
U.S. Army Waterways Experiment Station, DACW39-95-K-0101

The nature of the flow field associated with sediment resuspension caused by the passage of barge tows makes it quite difficult to formulate an appropriate flux boundary condition near the bed and thus to determine how much sediment will be incorporated into the water column. Barges generate turbulence by waves and by changes in the velocity profile due to water displacement. It is clear that the flow field resulting from the passage of vessels is unsteady, nonuniform, and highly turbulent. The main goal is to develop an entrainment function that can be used to estimate sediment resuspension due to barge tow passage, which includes the effect of mean bed shear stress as well as turbulence effects.

Interactions Between a Turbulent Boundary Layer and a Granular Movable Bed
M. García,* Y. Niño,* L. Ayala
University of Illinois; University of Chile (FONDECYT Project No. 1950592-95)

This research project aims at studying the formation and evolution of bedforms in open channel flows. In an experimental study conducted in a movable-bed flume, PIV measurements and flow/particle visualizations are used to relate bedform initiation and evolution with interactions between coherent flow structures and sediment transport phenomena taking place in the near-bed region of the flow. Linear and nonlinear theoretical analyses are used to study the threshold conditions for bedform emergence and equilibrium characteristics of fully developed bedforms. A cellular automata model is also used to simulate highly nonlinear processes taking place during the formation and evolution of bedforms.

Sediment Resuspension by Unsteady Turbulent Flows
M. H. García,* D. Admiraal
U.S. Army Research Office (AASERT), DAAH04-96-1-0132

All the available sediment entrainment functions have been developed for steady, uniform flow conditions. The ability of such functions to estimate sediment entrainment rates for bed shear stresses induced by unsteady flows has not been demonstrated nor has there been any attempt to develop entrainment functions that work for nonequilibrium conditions commonly found in environmental and industrial flows. A special-purpose facility is being used to study sediment resuspension by unsteady turbulent flows.

Navigation-induced Flow and Bed Shear Stresses
M. H. García,* D. Admiraal, J. Rodriguez
U.S. Army Waterways Experiment Station, DACW39-96-K-0005

Navigation-induced physical forces in the Upper Mississippi River System have to be quantified with the goal of mitigating associated environmental effects. A physical model of a navigation river located at the Waterways Experiment Station in Vicksburg, Mississippi, is being used to measure the flow field generated by the passage of a model vessel. A total of eight acoustic Doppler velocimeters and four flush-mounted hot-film sensors for measuring bed shear stresses are being used to capture the footprint of barges and their propellers.

Alluvial Resistance Analysis for Rivers with Dunes
M. García,* J. Fedele
University of Illinois

Dunes are sandwaves that appear as the most common feature in sandy-bed rivers. They are responsible for an important percentage of sediment transport as they move downstream, and they are responsible for the total resistance exerted on the flow. It is the intention of this study to relate the main processes occurring in the flow over a dune, in terms of characteristic flow structures (i.e., internal boundary layer development or wake propagation) and the spatially averaged variables that can be easily measured in field with current measurement techniques (i.e., mean geometric dimensions of bedforms, mean depth, mean flow velocity).

Batavia Dam Hydraulic Model Study, Fox River, Ill.
M. García,* J. Armbruster, A. Peabody, F. Bombardelli, M. Caisley, J. Schuster
Illinois Department of Natural Resources

The Batavia Dam is located at river mile 52.26 of the Fox River, just as it flows through downtown Batavia, Ill. The dam was constructed in the early 1800s so that water ponded behind the 5.8-ft structure could be used to power a saw and grist mill. In the early 1970s, however, the dam's structural integrity began to deteriorate. Today, these problems greatly impair the spillway's performance, especially during intense storm events. The main objective of the model study was to design, construct, and test alternative dam configurations that would repair or replace the existing Batavia Dam.

Numerical Simulation of Wind-induced Resuspension of Bed Sediment in Shallow Lakes
M. García,* F. Bombardelli
University of Illinois

Sediment resuspension in shallow lakes can lead to substantial water quality problems. High turbidity levels can result in reduced light penetration, which in turn can affect the growth of aquatic plants as well as the habitat for fisheries. There is a clear need for tools to assess the risk of wind-induced bed sediment resuspension. We are trying to find methodologies, based on numerical techniques, to address the problem.

Physical Model Study of the Boneyard Creek
M. García,* A. Waratuke, A. Peabody
University of Illinois

A 40-ft by 20-ft basin was constructed to contain a 1:16 scale model of an approximately 600-ft section of the Boneyard Creek where it enters the University of Illinois from Campustown. The purpose of the model is threefold: to aid in the validation of a computer model, to examine some very specific aspects of the modeled system (coefficients of discharge and the division of flow between the channel and the floodplain in high flow events), and to serve as a predictive tool to aid in the hydraulic design of channel modifications for flood control purposes.

Characterizing Multiscale Interaction of Hydrologic Processes Using Multisensor Satellite Data
P. Kumar*
National Aeronautics and Space Administration, NAG W-5247

To understand large-scale hydrologic processes, we need to characterize the feedback interaction between various systems such as land and atmosphere. Significant advances have been made in this direction through field campaigns to measure parameters from point to satellite pixel scale. However, the problem of assimilating measurements at various scales to understand the behavior of processes at small scales and their integrated effect on the larger scale is still elusive. The objectives of this research are to address this problem through the development of stochastic-dynamic multiscale models of key hydrologic processes. We will use the asynchronous multisensor observations from different satellite instruments for the study.

The Land Surface Component of the Climate System - Improved Representation of Subgrid Processes and Analyses of Land Surface Effects on Climate Variability
P. Kumar,* R. Koster* (NASA-GSFC), M. J. Suarez* (NASA-GSFC)
National Aeronautics and Space Administration, NAG 5-3661

The land surface affects precipitation variability partly through evaporation feedback as the water added to the surface during an anomalously large precipitation event leads to anomalously large evaporation rates, and these in turn can lead to further rainfall. The amplitude of the original precipitation anomaly is thereby increased. General circulation models are used to perform such studies. Two objectives of this research are: (1) to develop watershed-scale hydrologic parameterizations in GCM for modeling the effects of sub-basin-scale soil moisture variability on surface runoff, baseflow, and evaporation and (2) to study temporal and spatial structure of continental-scale hydrological fields using these improved parameterizations.

Characterizing Climatic Signatures in Hydro-Geomorphologic Response
P. Saco,* P. Kumar*
National Aeronautics and Space Administration Fellowship, NGT 5-30041

Traditionally, significant effort has been placed on studying streamflow variability that originates within the drainage basin due to land use, soil properties, geomorphology, etc. This emphasis has dominated despite the fact that initial variability imparted to a catchment by climate always precedes any subsequent variation that may arise in the basin itself. This research aims to identify parameters that describe the similarities and differences between the hydrologic response of large basins from different hydroclimatic regimes and find simple relationships between the parameters characterizing the climatology and the basin response. This research will enable us to better establish the link between climate and terrestrial hydrology.

Finding Principles of Large-Scale Hydrologic Response-Linking Hydroclimatology and River Basin Dynamics
P. Kumar*
National Science Foundation, EAR 97-06121

The objective of the research is to develop principles of large-scale hydrologic response in different hydroclimatological regimes by coupling hydroclimatology and river basin dynamics. This will be accomplished by (1) performing a joint analysis of the atmospheric-hydrologic cycle and streamflow to develop parameterizations to link hydroclimatology and basin response characteristics; (2) developing a nondimensional formulation of large-scale basin response which explicitly incorporates the hydroclimatological influence; and (3) performing validation studies.

The Spatial and Temporal Variability of Summertime Precipitation in the Midwestern United States
P. Kumar,* M. Ting* (Atmos. Sci.)
National Oceanic and Atmospheric Administration, COM NA 86GP0094

The objective is to identify the spatial and temporal scales of variability of precipitation with emphasis on flood and drought years and to establish their physical basis by drawing connections with the atmospheric circulation features, as well as external climatic forcings. We will use both the hourly precipitation data of the U.S. and the general circulation model output. By comparing observations with the GCM data, we will address the similarities and differences in scales of variability of precipitation between model and observations, thereby providing a diagnostic study. This will lead to better model simulation and prediction of the observed precipitation variability in the summer.

Modeling of Coupled Processes in Subsurface Transport of Reactive Contaminants
A. J. Valocchi,* B. E. Rittmann* (Northwestern Univ.), F. Espinoza, G. Hammond
U.S. Department of Energy, Subsurface Science Program

The overall objective is to develop and apply a multidimensional transport model for multiple components undergoing equilibrium or kinetically controlled chemical and biological reactions. The model will be used to analyze the results of experiments being conducted by other investigators on the transport of organically complexed radionuclides in two-dimensional flow cells. The model will also be used as a tool to investigate the impact of small-scale spatial variability in aquifer geochemical properties upon transport over large spatial and temporal scales.

Research and Development of a Reactive Transport Model for the FEHM Computer Code
A. J. Valocchi,* H. Viswanathan, G. Hammond
Los Alamos National Laboratory, C84740016-3Y

FEHM is one of several models being used to determine the viability of the Yucca Mountain site for long-term storage of high-level radioactive waste. The code is very powerful and flexible and can simulate coupled heat and mass transport in three-dimensional multiphase systems. We are making significant enhancements to give FEHM the capability to simulate general equilibrium or kinetic reactions among a subset of significant chemical components. We are using the enhanced FEHM to simulate the transport of neptunium, plutonium, and technetium; these radionuclides have been targeted for study because of their large inventory in the potential repository and their high solubility in typical Yucca Mountain groundwater.

Transport of Multiple Contaminants in Porous Media with Spatially Variable Reactive Properties
A. J. Valocchi,* F. Espinoza
U.S. Department of Energy, Subsurface Science Program

Most realistic groundwater pollution problems involve multiple components that undergo several different reactions with solid phases comprising the porous medium. Also, real porous media exhibit spatial variability in their physical and geochemical properties. We are conducting theoretical investigations of the transport of simple multicomponent systems in porous media comprised of a random assemblage of reactive and nonreactive zones. We are using Monte Carlo simulation and approximate perturbation methods to address questions related to upscaling and prediction uncertainty.

Traveling Wave Behavior during Subsurface Transport of Biologically Reactive Contaminants - Implications for In Situ Bioremediation
A. J. Valocchi,* F. Espinoza
NSF/EPA Partnership for Environmental Research, Water and Watersheds Programs

It is widely believed that aquifer heterogeneity and other transport-related factors play a key role in determining the ultimate success of any particular bioremediation project. This project focuses on an important transport-related limitation that arises due to the fact that the background contaminants are usually adsorbed onto the aquifer solids, while the input-limiting nutrients do not undergo adsorption reactions. For simplified 1-D systems, analytical and numerical studies show that the spatial profiles of the organic pollutant, electron acceptor, and biomass can be described mathematically as traveling waves. An important practical consequence is that there is a long-term maximum possible biodegradation rate which is a function of transport parameters rather than biological parameters.

Pollutant Transport in Groundwater - Interactive Simulation and Transport over the World Wide Web
A. J. Valocchi,* G. Hammond
University of Illinois

In courses covering transport processes in groundwater and soil systems, students use physical principles to construct mathematical models that simulate pollutant migration. These models are in the form of partial differential equations which usually require numerical solution techniques. Although commercially available software packages exist for solving these equations, these packages are cumbersome for most students. This project entails development of interactive web-based interfaces for transport simulation models. Students will be able to enter input data in web "forms" format, and then click on options to run remote simulation programs on the web server. The program output is displayed graphically and numerically back to the web browser.

Stream Channel Migration Effects on Bridge Approaches and Conveyance
B. C. Yen,* M. H. García,* J. Armbruster
Illinois Transportation Research Center, IDOT ITRC CP 96013

The main objective of this study is to identify and evaluate effective method(s) to control undesirable stream channel migration that would adversely affect bridge approaches and conveyances, and accordingly, to recommend potential alternatives and future work that could lead to low-cost erosion control and bridge maintenance. Of particular interest is the possibility of using environmentally friendly techniques, such as vegetation, for the stabilization of stream banks.

Unsteady Flow in Open Channels
B. C. Yen,* J. A. Gonzalez-Castro, W. S. Tsai
University of Illinois; University of Pisa, Italy

A fundamental study on the unsteady flow equations in open channels is carried out theoretically and numerically. Significance of the terms and coefficients (correction factors for velocity and pressure distributions) was studied numerically. The kinematic wave, noninertia, and Saint-Venant approximations of the exact moment equations were considered. Demarcation of applicability of these approximations is sought. The importance of the downstream backwater on the selection of the models is investigated. A new reliable quasi-steady flow routing method minimizing numerical problems is being developed.

Reliability Analysis in Hydrosystems Engineering
B. C. Yen*
University of Illinois

This research is to investigate the possibility of developing, as a complement to the conventional hydraulic structure design and evaluation methods which consider only the basic hydrologic risk of return period and frequency analysis, alternative approaches for reliability analysis that would account for all the hydrologic as well as nonhydrologic risks and uncertainties. Among the different risk-analysis methods investigated, the first-order methods have been applied to the design of sewers, culverts, levees, dams, and similar structures.

Urban Drainage
B. C. Yen,* J. A. Gonzalez-Castro
University of Illinois

This is a comprehensive, long-term research program to investigate the hydraulics, hydrology, sediment transport, and optimization of urban stormwater drainage on the land surface as well as in sewers. Current emphasis is on development of a noninertia hydrodynamic sewer network flow routing model, determination of Boneyard Creek drainage capacity, identification of drainage bottlenecks, and on the hydraulic-hydrologic characteristics of infiltration trenches.

Resistance in Open Channels
B. C. Yen*
University of Illinois

A comprehensive investigation of the hydraulic resistance in open channels was conducted based on the dimensional analysis and boundary layer theory. Resistance of uniform channels, composite channels, compound channels, and alluvial channels was investigated in view of momentum and energy concepts and point, cross section, and reach coefficients. Currently, study is on resistance for channels with floodplains.

Sediment Fall Velocity in Oscillating Flow
B. C. Yen,* T.-Y. Chang
University of Illinois

The fall velocity of a single solid sphere in a vertically oscillating fluid field was investigated in order to provide basic information on sediment behavior in turbulent flows in natural water bodies. A survey of relevant existing information was conducted. The Basset-Boussinesq-Oseen equation was improved for simulations. The terminal fall velocity reduction factor is determined as a function of the particle Reynolds number and oscillation parameters. Particle levitation and hovering against gravity could occur with asymmetric fluid oscillations, whereas for symmetric fluid oscillation, the particle will eventually fall, no matter how slowly.

Geomorphologic Unit Hydrograph
B. C. Yen,* K. T. Lee*
University of Illinois; National Taiwan Ocean University

The objective of this study is to derive the unit hydrograph of a watershed using only a topography map without requiring past records of rainfall. This is accomplished through probabilistic and kinematic wave considerations of the travel time of the water drops of the unit depth into the watershed through which the geomorphological instantaneous unit hydrograph (GIUH) is established. The GIUH can be applied to any effective rainfall through convolution to produce the direct runoff hydrograph.

Hydraulic Performance Graph for Channel Capacity Determination
B. C. Yen,* J. A. Gonzalez-Castro
University of Illinois

This research is to develop a new method to determine open channel flow capacity under backwater effects. A hydraulic performance graph is first developed summarizing the subcritical flow backwater profile conditions for all the feasible upstream and downstream water levels and discharges. The channel capacity can be determined accordingly as the marginal condition of just-bankfull stage without spilling overbank at the most critical point in the channel.

Risk Analysis for Dam Safety Assessment
B. C. Yen,* H.-F. Lin, W. S. Tsai
Tjing Ling Industrial Research Institute, Taiwan

Application of risk and uncertainty analyses as an alternative for dam safety assessment in Taiwan is pursued. Various methodologies, such as fault-tree and event tree analyses and first-order and point-estimation techniques, are evaluated. The concept and techniques permit consideration of all quantifiable contributing factors. In this project, the hydrologic and hydraulic factors are analyzed in detail.

Conjunctive Surface-Subsurface Flow Modeling
B.C. Yen,* M. Morita*
University of Illinois; Shibaura Institute of Technology, Japan

In this study, overland surface and groundwater flows are simulated simultaneously. Previously, a one-dimensional surface flow and a two-dimensional subsurface conjunctive numerical model were developed. In the present phase, a conjunctive model of the 2-D overland surface flow and the 3-D subsurface flow in unsaturated and saturated porous media is formulated. Several numerical methods have been evaluated.