Geology topics

David J. Holtschlag

Publications and source records attributed to David J. Holtschlag.

28 records · Page 2Linked to original sources

USGS2002

Visualization of drifting buoy deployments on upper Detroit River within the Great Lakes Waterway from August 28-30, 2001

Detroit River is a connecting channel on the Great Lakes waterway that joins Lake St. Clair with Lake Erie. The river forms part of the international boundary between the United States and Canada in southeastern Michigan and southern Ontario. Drifting buoys were deployed on Detroit River to help investigate flow characteristics of four selected reaches as part of a source water assessment study of public water intakes. The drifting buoys contained global positioning system (GPS) receivers to help track their movements following their deployment. In some deployments, buoys were released across a transect at approximately uniform intervals to better understand flow patterns. In other deployments, buoys were released in clusters to investigate turbulent dispersion characteristics. Computer animations of buoy movements, which can be viewed through the Internet, are developed to help visualize the results of the buoy deployments.

Detroit River↗

USGS2002

Visualization of a drifting buoy deployment on Lake St. Clair within the Great Lakes Waterway from August 12-15, 2002

Lake St. Clair is a 430 square mile lake between the state of Michigan and the province of Ontario, which forms part of the international boundary between the United States and Canada in the Great Lakes Basin. Lake St. Clair receives most of its inflow from Lake Huron through St. Clair River, which has an average flow of 182,000 cubic feet per second. The lake discharges to Detroit River, where it flows 32 miles to Lake Erie. Twelve drifting buoys were deployed on Lake St. Clair for 74 hours between August 12-15, 2002 to help investigate flow circulation patterns as part of a source water assessment study of the susceptibility of public water intakes. The buoys contained global positioning system (GPS) receivers to track their movements. Buoys were released in a transect between tethered buoys marking an 800-foot wide navigational channel in the north-central part of the lake just downstream of St. Clair River, and about 15.5 miles northeast of Detroit River. In addition, an acoustic Doppler current profiler (ADCP) was used to measure velocity profiles in a grid of 41 points that spanned the area through which the buoys drifted. Computer animations, which can be viewed through the Internet, were developed to help visualize the results of the buoy deployments and ADCP measurements.

Michigan↗

USGS2002

A two-dimensional hydrodynamic model of the St. Clair-Detroit River waterway in the Great Lakes basin

The St. Clair-Detroit River waterway connects Lake Huron with Lake Erie in the Great Lakes basin to form part of the international boundary between the United States and Canada. A two-dimensional hydrodynamic model is developed to compute flow velocities and water levels as part of a source water assessment of public water intakes. The model, which uses the generalized finite-element code RMA2, discretizes the waterway into a mesh formed by 13,783 quadratic elements defined by 42,936 nodes. Seven steady-state scenarios are used to calibrate the model by adjusting parameters associated with channel roughness in 25 material zones. An inverse modeling code is used to systematically adjust model parameters and to determine their associated uncertainty by use of nonlinear regression. Calibration results show close agreement between simulated and expected flows in major channels and water levels at gaging stations. Sensitivity analyses describe the amount of information available to estimate individual model parameters, and quantify the utility of flow measurements at selected cross sections and water-level measurements at gaging stations. Further data collection, model calibration analysis, and grid refinements are planned to assess and enhance two-dimensional flow simulation capabilities describing the horizontal flow distributions in St. Clair and Detroit Rivers and circulation patterns in Lake St. Clair.

St. Clair-Detroit River waterway↗

USGS2001

Visualization of drifting buoy deployments on St. Clair River near public water intakes - October 3-5, 2000

St. Clair River is a connecting channel of the Great Lakes between Lake Huron and Lake St. Clair. The river forms part of the international boundary between the United States and Canada in the eastern Lower Peninsula of Michigan and southern Ontario. Drifting buoys were deployed to help investigate flow characteristics near public water intakes in ten reaches of St. Clair River from October 3-5, 2000. In eight deployments, buoys were released at uniform intervals in a transect across the river to better understand flow patterns. In the remaining six deployments, buoys were released in a cluster near the middle of the channel to study turbulent dispersion characteristics. The eight spherical and seven cylindrical buoys used in the study were equipped with drogues and had similar drift characteristics. Each buoy contained a geographical positioning system (GPS) to monitor its movement. Computer animations were developed that integrated these GPS data with data shown on navigational charts. These computer animations, which can be viewed through the Internet, provide a scientific visualization tool to study the deployments.

Michigan↗

USGS1999

A temporal and spatial analysis of ground-water levels for effective monitoring in Huron County, Michigan

Quarterly water-level measurements were analyzed to assess the effectiveness of a monitoring network of 26 wells in Huron County, Michigan. Trends were identified as constant levels and autoregressive components were computed at all wells on the basis of data collected from 1993 to 1997, using structural time series analysis. Fixed seasonal components were identified at 22 wells and outliers were identified at 23 wells. The 95- percent confidence intervals were forecast for water-levels during the first and second quarters of 1998. Intervals in the first quarter were consistent with 92.3 percent of the measured values. In the second quarter, measured values were within the forecast intervals only 65.4 percent of the time. Unusually low precipitation during the second quarter is thought to have contributed to the reduced reliability of the second-quarter forecasts. Spatial interrelations among wells were investigated on the basis of the autoregressive components, which were filtered to create a set of innovation sequences that were temporally uncorrelated. The empirical covariance among the innovation sequences indicated both positive and negative spatial interrelations. The negative covariance components are considered to be physically implausible and to have resulted from random sampling error. Graphical modeling, a form of multivariate analysis, was used to model the covariance structure. Results indicate that only 29 of the 325 possible partial correlations among the water-level innovations were statistically significant. The model covariance matrix, corresponding to the model partial correlation structure, contained only positive elements. This model covariance was sequentially partitioned to compute a set of partial covariance matrices that were used to rank the effectiveness of the 26 monitoring wells from greatest to least. Results, for example, indicate that about 50 percent of the uncertainty of the water-level innovations currently monitored by the 26- well network could be described by the 6 most effective wells.

Michigan↗

USGS1998

Indirect ground-water discharge to the Great Lakes

Estimates of the average ground-water component of streamflow for 195 streams in the United States part of the Great Lakes Basin range from 25 to 97 percent. Among the selected streams, the average ground-water component of streamflow was 67.3 percent. Estimates of the ground-water component of streamflow are based on hydrograph separation of 5,735 years of daily streamflow data. Incorporation of these estimates into the basin water supply for the Great Lakes shows that indirect discharge of ground water to the Great Lakes ranges from 22 percent of the basin water supply of Lake Erie to 42 percent of the basin water supply for Lake Ontario.

Great Lakes↗

USGS1997

A generalized estimate of ground-water-recharge rates in the Lower Peninsula of Michigan

Ground-water recharge rates were estimated by analysis of streamflow, precipitation, and basin-characteristics data. Streamflow data were partitioned into ground-water-discharge and surface-water-runoff components. Regression equations relate ground-water discharge to precipitation at each basin. Basin-characteristics and long-term precipitation data were used to aid in the interpolation of recharge characteristics within gaged and ungaged areas. A multiple regression equation was developed to estimate spatial variation of recharge. The generalized estimate provides a consistent method for approximating recharge rates in the Lower Peninsula of Michigan.

Water Supply Paper↗

USGS1996

A dynamical-systems approach for computing ice-affected streamflow

A dynamical-systems approach was developed and evaluated for computing ice-affected streamflow. The approach provides for dynamic simulation and parameter estimation of site-specific equations relating ice effects to routinely measured environmental variables. Comparison indicates that results from the dynamical-systems approach ranked higher than results from 11 analytical methods previously investigated on the basis of accuracy and feasibility criteria. Additional research will likely lead to further improvements in the approach.

Iowa↗

USGS1996

Simulation of ground-water flow in the Saginaw Aquifer, Clinton, Eaton, and Ingham counties, Michigan

A numerical model was developed to simulate ground-water flow in the Tri-County region, which consists of Clinton, Eaton, and Ingham Counties, Michigan. This region includes a nine-township area surrounding Lansing, Michigan. The model simulates the regional response of the Saginaw aquifer to major groundwater withdrawals associated with public-supply wells. The Saginaw aquifer, which is in the Grand River and Saginaw Formations of Pennsylvanian age, is the primary source of ground water for Tri-County residents. The Saginaw aquifer is overlain by glacial deposits, which also are important ground-water sources in some locations. Flow in the Saginaw aquifer and the glacial deposits is simulated by discretizing the flow system into model cells arranged in two layers. Each cell, which corresponds to a land area of 0.0625 square mile, represents the locally averaged properties of the system. The spatial variation of hydraulic properties controlling ground-water flow was estimated by geostatistical analysis of 4,947 well logs. Parameter estimation, a form of nonlinear regression, was used to calibrate the flow model. Results of steady-state ground-water-flow simulations show close agreement between water flowing into and out of the model area for 1992 pumping conditions; standard error of the difference between simulated and measured heads is 14.7 feet. Simulation results for three alternative pumping scenarios for the year 2020 show that the glacial aquifer could be dewatered in places if hypothetical increases in pumping are not distributed throughout the Tri-County region. Contributing areas to public-supply wells in the nine-township area were delineated by a particle-tracking analysis. These areas cover about 121 square miles. Contributing areas for particles having travel times of 40 years or less cover about 42 square miles. Results of tritium sampling support results of model simulations to delineate contributing areas.

Michigan↗

USGS1981

Flow model of Saginaw River near Saginaw, Michigan

An unsteady-flow simulation model was applied to a 19.5-mile reach of Saginaw River. The model provides a method of determining instantaneous discharge for flows from -8,000 to 12,000 cubic feet per second. The currently used slope-rating method can be utilized to compute discharge only under steady and high-flow conditions. Unsteady flow frequently occurs in the Saginaw River as a result of lake seiching. Model computations are based on solution of the continuity and momentum flow equations, on hydraulic characteristics of Saginaw River, and on time-dependent boundary conditions. An implicit, finite-difference technique is used to solve the one-dimensional flow equations. Channel storage and conveyance characteristics were obtained from data collected during a 1979 field survey and through model calibration. Boundary conditions are specified by stage or discharge data at the model extremities. Optionally, wind velocity data are incorporated in the flow simulations. The model can simulate instantaneous stage and discharge data and summarize or plot the data. Simulations of low-flows are sensitive to small errors in stage data and to gentle breezes. Simulation of high flows for present channel conditions requires additional data and further study.

Michigan↗