Robert Holmes, Jr., Ph.D., P.E., F.ASCE, F.EWRI, D.WRE (Former Employee)

A new method is proposed to simulate groundwater age directly, by use of an advection-dispersion transport equation with a distributed zero-order source of unit (1) strength, corresponding to the rate of aging. The dependent variable in the governing equation is the mean age, a mass-weighted average age. The governing equation is derived from residence-time-distribution concepts for the...

Heron Pond, located in extreme southern Illinois, lies immediately adjacent to the upper Cache River. The upper Cache River is encroaching on Heron Pond, which has raised the issue of the possibility of a failure of the Heron Pond wall, the area between Heron Pond and the upper Cache River. Hydraulic, geotechnical, geomorphic, and biologic data were collected by the U.S. Geological...

A simplified method to estimate total-streambed scour was developed for application to bridges in the State of Illinois. Scour envelope curves, developed as empirical relations between calculated total scour and bridge-site chracteristics for 213 State highway bridges in Illinois, are used in the method to estimate the 500-year flood scour. These 213 bridges, geographically distributed...

A simplified method to estimate total streambed scour was developed for application to approximately 10,000 Local Agency bridges (bridges owned by local governments and not by the State of Illinois). This method consists of using total scour-envelope curves, developed as empirical relations between calculated total scour and bridge characteristics for 303 State Highway Bridges, to...

Important rainfall-runoff characteristics for basins in the Rolla, Missouri, area were determined to be overland flow, interception storage, interception losses, evaporation, and infiltration. Using these characteristics, the U.S. Environmental Protection Agency's Stormwater Management Model (SWMM) was configured for basins in the study area. The data network for the model calibration...

Analytical and numerical solutions are employed to examine the concentration history of a dissolved substance in water pumped from a leaky aquifer. Many aquifer systems are characterized by stratification, for example, a sandy layer overlain by a clay layer. To obtain information about separate hydrogeologic units, aquifer pumping tests are often conducted with a well penetrating only...

Determining the rheologic properties of coarse- grained mass flows is an important step to mathematically simulate potential inundation zones. Using the vertically rotating flume designed and built by the U.S. Geological Survey, laboratory procedures and subsequent data reduction have been developed to estimate shear stresses and strain rates of various flow materials. Although direct...

During unsteady or transient ground-water flow, the fluid mass per unit volume of aquifer changes as the potentiometric head changes, and solute transport is affected by this change in fluid storage. Three widely applied numerical models of two-dimensional transport partially account for the effects of transient flow by removing terms corresponding to the fluid continuity equation from...

A new three-dimensional model of solute transport in groundwater that is based on a widely used two-dimensional method of characteristics model and is coupled to a modular finite-difference flow model is under development. The model's accuracy for ideal aquifers having homogeneous properties, uniform boundary conditions, and steady flow along a grid direction is demonstrated by...

Desbarats [1990] used a particle-tracking scheme to investigate the physics of three-dimensional solute transport in aquifers composed of two porous media of different hydraulic conductivities. The spatially heterogeneous fluid velocity was assumed to be the only mechanism of solute movement; local or pore scale dispersion and molecular diffusion were assumed to be negligible. The...

Moreno et al. [1988] (hereinafter referred to as MT) used a particle-tracking scheme to investigate the physics of solute movement in a variable-aperture planar fracture. The spatially heterogeneous fluid velocity was assumed to be the only mechanism of solute movement; local or pore scale dispersion and molecular diffusion were assumed to be negligible. The particle-tracking scheme used...

This paper investigates the effects of transient groundwater flow on dispersion of a waste chloride plume in the basaltic aquifer beneath the Idaho (USA) National Engineering Laboratory. In an early application of numerical modeling techniques to the two-dimensional simulation of field-scale plumes, previous investigators identified longitudinal and transverse dispersivities using an...