Geology topics

Research about Lake County, Illinois

Source-linked reports with geographic coverage including Lake County, Illinois.

2 recordsLinked to original sources

USGS2010

Hydrology, water quality, and causes of changes in vegetation in the vicinity of the Spring Bluff Nature Preserve, Lake County, Illinois, May 2007–August 2008

Agriculture and urbanization have altered the hydrology and water quality of the coastal wetland complex along the shore of Lake Michigan at the Spring Bluff Nature Preserve and Illinois Beach State Park in northeastern Lake County, Ill., and the adjacent Chiwaukee Prairie State Natural Area in southeastern Wisconsin. Culverts, roads, ditches, and berms installed within the wetland complex have altered the natural directions of surface-water flow and likely have increased the natural hydroperiod in the Spring Bluff Nature Preserve and decreased it in the northern part of the Illinois Beach State Park. Relative to presettlement conditions, surface-water runoff into the wetlands likely is greater in quantity and higher in concentrations of several constituents, including chloride, nitrate, phosphorous, and suspended sediment. These constituent concentrations are affected by a variety of factors, including the amount of agricultural and urban land use in the watersheds. Hydrologic, chemical, and biologic processes within the wetland communities reduce the concentrations of these constituents in surface water before the water discharges to Lake Michigan by as much as 75 percent for chloride, 85 percent for nitrate, 66 percent for phosphorous, and more than an order of magnitude for suspended sediment. However, concentrations of phosphorous and suspended sediment in surface water increased within parts of the wetland complex. Given these changes, the floristic quality of these wetlands has been altered from the historic condition. Specifically, Typha spp. and Phragmites australis occur in greater numbers and over a larger area than in the past. The spread of Typha spp. and Phragmites australis appears to be enhanced by anthropogenic alterations within the wetland complex, such as increased water levels and duration of inundation and, possibly, increases in the total concentration of dissolved constituents in water.

Illinois↗

USGS1995

Regional rainfall-runoff relations for simulation of streamflow for watersheds in Lake County, Illinois

Rainfall and streamflow data collected in Lake County, Ill., from March 1990 through September 1993 were used to (1) calibrate a rainfall-runoff model for an area encompassing three watersheds (individual areas of 17.2, 35.7, and 37.0 mi 2 (square miles) and (2) verify the regional model parameter set obtained from the calibration by applying the parameter set to rainfall-runoff models for an additional small (6.3 mi 2 ) watershed and a large (59.6 mi 2 ) watershed. In addition, rainfall and streamflow data collected from April 1991 through September 1993 were used to calibrate the rainfall-runoff model for three single land-use watersheds (38.2-305 acres), called hydrologic response units (HRU's). Significant differences were found between the best parameters used in the HRU models and in the larger watershed models. The main channels in the HRU's are intermittent streams; thus, the parameters in the HRU models were selected such that a fluctuating water table could be simulated; runoff from the larger watersheds is not as sensitive to the effects of a fluctuating water table. Classification of land cover into two pervious subareas (forest and grass) and one impervious subarea (including parking lots, streets, and rooftops, among others) was sufficient to simulate the rainfall-runoff relations for all watersheds accurately. The model parameters presented in this report, which were refined through regional calibration and verified for watersheds not considered in the calibration, allow simulation of runoff in watersheds in Lake County, Ill., with approximately 93-percent accuracy in the total water balance, an average absolute error in the annual- flow estimates of 10.9 percent (and an error rarely exceeding 25 percent for annual flow), and monthly water balances with correlation coefficients of 93 percent and coefficients of model-fit efficiency of 86 percent. The models closely reproduced the partial-duration series of runoff and storm-runoff frequencies for the modeled watersheds.

Illinois↗