Geology topics

G.P. Johnson

Publications and source records attributed to G.P. Johnson.

3 recordsLinked to original sources

USGS2004

Preliminary results of a dam-removal analysis on brewster creek near st. Charles, Illinois, 2002-2004

The benefits of gradually removing a dam (through multiple notches) are to reduce the total project cost and reduce possible environmental effects by allowing the impounded sediment to slowly move downstream, and a stable stream and revegetated floodplain to form upstream. Notching, in this study of a dam on Brewster Creek, near St. Charles, Illinois, involves cutting a given height (in five 12-18 inch notches over approximately a 9 month period) across the length (or some portion of the length) of the dam. Brewster Creek is a tributary of the Fox River in northeastern, Illinois. Sediment, dissolved oxygen, and geomorphic response are being monitored before, during, and after a gradual (notching) removal of the dam. The study area includes the creek reach immediately below the dam and above the lake. Preliminary data analysis indicate that during and after the removal, the relation between the sediment transported to the study area from upstream and the sediment transported out of the study area remained relatively stable. This preliminary result indicates that the notching system created a fairly slow and predictable sediment transport response to storms, when compared to known upstream sediment loads. This result corresponds to the slow geomorphic response at the site since inception of the notching sequence in 2003. The creek responded to the five notches removed over the course of 9 months by gradually cutting through the former lakebed sediment to establish a meandering channel. Notchings did not appreciably affect dissolved oxygen concentrations in Brewster Creek.

Conference Paper↗

USGS1997

Field-scale tests for determining mixing patterns associated with coarse-bubble air diffuser configurations, Egan Quarry, Illinois

The U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, Chicago District did field-scale tests in August-September 1996 to determine mixing patterns associated with different configurations of coarse-bubble air diffusers. The tests were done in an approximately 13-meter deep quarry near Chicago, Ill. Three-dimensional velocity, water-temperature, dissolved oxygen concentration, and specific-conductivity profiles were collected from locations between approximately 2 to 30 meters from the diffusers for two sets of five test configurations; one set for stratified and one set for destratified conditions in the quarry. The data-collection methods and instrumentation used to characterize mixing patterns and interactions of coarse-bubble diffusers were successful. An extensive data set was collected and is available to calibrate and verify aeration and stratification models, and to characterize basic features of bubble-plume interaction.

Conference Paper↗

USGS1995

Dendrogeomorphic estimate of changes in sedimentation rate along the Kankakee River near Momence, Illinois

Changes in sedimentation rates wee estimated using root-burial depth and tree-age data at six selected data-collection sites along the Kankakee River near Momence in Kankakee County, Illinois. Five sites were in backwater areas away from the river channel, and one site was on a natural levee near the channel. A summary of the dendrogeomorphic data at the six sites indicates that sedimentation rates were greater after 1950 than before 1950. Greater sedimentation rates after 1950 were observed at four of the five backwater sites, whereas no change in sedimentation rate after 1950 was observed at the fifth backwater site. The observed rates could have been affected by any combination of soil erosion, soil compaction, or increased streamflow. A greater sedimentation rate after 1950 was observed at the levee site, which appeared to have been affected by erosion from a flood in 1950. Effects of erosion were not observed at any of th other sites. No erosional effects and soil not susceptible to compaction at the five backwater sites indicate that neither erosion nor compaction affected observed sedimentation rates. The effect of increased stream- flow in the Kankakee River Basin since the early 1900's on the observed sedimentation rates is not known.

Water-Resources Investigations Report↗