Fox River Watershed Investigation: Stratton Dam to the Illinois River: Phase II Blackberry Creek and Poplar Creek Hydrologic and Water Quality Simulation Models: Executive Summary

Fox River Study Group, Inc.published or submitted for publicationis peer reviewe

Impacts of Urbanization and Climate Variability on Floods in Northeastern Illinois

Illinois-Indiana Sea GrantOpe

City of Charleston public water supply: analysis of drought yields from the Charleston side-channel reservoir

"Prepared for the City of Charleston.""April 1996.

Embarras River watershed digital floodplain mapping, Champaign County, Illinois

The project objective was to assimilate the best available data to prepare digital maps of critical riparian corridors and areas at risk of flooding for the upper Embarras River, East Branch Embarras River, and Black Slough in Champaign County. Hydrologic, hydraulic, and digital data defining streams and floodplains were reconciled with digital orthophotos of the Embarras watershed. Using orthophotos as base maps, digital data sets were prepared of streams and rivers and floodplain boundaries expected for a flood having a one percent chance of occurrence in any given year. These maps were developed to provide easy-to-interpret information that identifies areas at risk during flood events. The maps were developed using ESRI ArcGIS 8.1 software and are on the attached CD-ROM in ready-to-print PDF format. The CD-ROM format is compatible with Microsoft Windows Operating System Version 95 or later. The CD-ROM contains the HEC-RAS hydraulic model used to simulate flood elevations, digital coverages used to compose the maps, digital photos of bridge crossings and landscapes of the watershed, and this report. Graphs of channel thalweg and water surface profiles showing the depth of flooding for the biennial flood event (2-year flood) and the one-percent annual chance of occurrence flood (100-year flood) provide additional information

Fox River watershed investigation: Stratton Dam to the Illinois River: water quality issues and data report to the Fox River Study Group, Inc.

"Prepared for the: Fox River Study Group, Inc.""March 2004.""Prepared by: Illinois State Water Survey, Watershed Science Section."CD-ROM includes corresponding database and GIS datasets.Includes bibliographical references

Flood Hazards and Flood Risk, the Impact of a Changing Climate

Ope

Illinois River Levees: Sizing Up Their Impact on Flooding and Risk

The Illinois River is separated from its floodplain by a series of levees constructed and modified over time. These levees are subject to overtopping, but the frequency of the critical flood event varies from levee system to system and is not generally known. Investigations to consider reconnecting the river and its floodplain, building resilient river communities, and potentially diverting floods to agricultural land all require information about the land area, land use, structures, and population of each levee protected area. The objective of this research is to provide a comprehensive description of the leveed area along the Illinois River. Using the United States Army Corps of Engineers (USACE) National Levee Database (NLD), levee systems along the Illinois River were identified based on the availability of highly detailed topographic data. Each levee system was then analyzed in conjunction with the Upper Mississippi River System Flow Frequency Study (UMRSFFS) to determine the critical flood event expected to overtop each levee system. Based on this overtopping analysis, the areas of inundation landward of each levee system were studied using flooding depth and demographic and economic analysis to produce a representative summary of the risk for each levee system. Flooding depth grids were produced for each levee system representing the extent and depth of inundation expected when a levee system first overtops. Economic analysis included both investigation of average agricultural production per levee system using United States Department of Agriculture soil and crop data, and structural risk exposure using the Federal Emergency Management Agency Hazus-MH risk analysis software. The 35 levee systems studied have an annual chance of overtopping ranging from 6.9% to less than 0.2% (or 14 to >500 years on average). The average depth of flooding for a levee system due to overtopping ranges from 5.3 feet to 24.1 feet. Across all levee systems analyzed (206,000 acres), the average depth of flooding due to overtopping was 15.4 feet. This suggests that more than 3.1 million acre-feet of floodplain storage is currently disconnected from the Illinois River by the studied levees. The average gross economic value of crops grown within the levee systems included in this analysis was approximately 130 million dollars per year (based on crop years 2010–2012). Nearly 80% of the land area within the levee systems is devoted to the production of corn and soybeans. The remainder of the land area is evenly divided (about 5% each) among developed lands, open water, and pasture/hay. The population living within the Illinois River levee systems decreased approximately 1% between 2000 and 2010 to just over 9,500. More than 90% of the studied population lives within just 3 of the 35 studied levee systems. Although diversity increased slightly between 2000 and 2010, the population remains predominately white. Nearly 60% of the population is aged 18-64 with 26% less than 18 and 14% greater than 64. Hazards analysis using the Federal Emergency Management Agency Hazus-MH utility and overtopping projections produces an estimate of total exposure to the General Building Stock (GBS). These exposure estimates range, in terms of full building replacement value, from insignificant for small agricultural levees to more than 660 million dollars in developed urban areas. Expected damages due to overtopping range from insignificant to more than 155 million dollars. The total exposure to the GBS across all studied levee systems was more than $1.1 billion. Damages to the GBS due to overtopping of all levee systems is expected to be more than 265 million dollars.National Great Rivers Research and Education Centerpublished or submitted for publicationis peer reviewedOpe

Yield assessment for Lake Vermilion, Vermilion County

"February 2001.""Contract report 2001-04.""Prepared for the Consumers Illinois Water Company, Vermilion Division.

Mitigative Measures for At-risk Public Surface Water Supply Systems in Illinois

published or submitted for publicationis peer reviewedOpe

Communicating the Impacts of Potential Future Climate Change on the Expected Frequency of Extreme Rainfall Events in Cook County, Illinois

A novel methodology for determining future rainfall frequency is described in this report. Isohyetal maps illustrate how heavy precipitation may change in the future, but the results have a high level of uncertainty expressed as very wide confidence limits. Uncertainty in possible future conditions is much greater than the uncertainty identified for current commonly used precipitation analyses. The resulting isohyetal maps do not replace existing sources, such as Illinois State Water Survey (ISWS) Bulletin 70 (Huff and Angel, 1989) or National Oceanic and Atmospheric Administration (NOAA) Atlas 14 (Bonnin et al., 2006). Presently, the ISWS is updating Bulletin 70 (Huff and Angel, 1989) for subregions of Illinois. Some of these updates will include projected rainfall frequency. The key objectives of this study are to i) design a framework to translate future climate scenarios into a product that engineers and planners can use to quantify the impact of climate change, and ii) demonstrate how climate model output can be used to inform and plan adaptive strategies for stormwater and floodplain management. The framework in this study is illustrated using the observed and projected rainfall data in Cook County, Illinois, providing a road map to evaluate climate change impacts on urban flooding and a plan for adaptation. Numerous studies attempt to identify the implications of climate change with respect to hydrologic extremes (e.g., IPCC, 2007; CCSP, 2008; Milly et al., 2008). These studies project future climate conditions with more frequent extreme precipitation events in many regions around the world, including parts of the United States. In particular, it has been projected that northeastern Illinois, including the Chicago metropolitan area, will experience more frequent and more intense rainfall events in the future (Markus et al., 2012), which will lead to more intense and more frequent urban flooding events and to increased human, environmental, and economic risks. Thus, various planning and management measures need to be considered by urban communities which are responsible for administering ordinances governing the construction and maintenance of stormwater management systems, and for floodplain management to address public safety concerns, property damage, and economic interruption from intense precipitation. In these efforts, effective communication of climate change impacts on urban watersheds/sewer sheds is needed. Data should be delivered at the watershed level in a form that can be incorporated in watershed planning at the community level. Delivery of useful climate change information is critical for community planning and adaptation to changing climate conditions. It is common practice that future climate projections, which are based on global circulation models (GCM), are downscaled to finer temporal and spatial scales using statistical or dynamical downscaling models. However, watershed-scale climate data generated by climate models still do not provide precipitation data in a format useful for community engineers and planners to prepare, mitigate, and adapt to future conditions. Furthermore, city managers and decision makers need quantifiable future risk to demonstrate the need for adaptive actions, such as retrofitting storm sewers and other water conveyance structures or adopting higher regulatory design standards within the community. This is not offered by the present climate modeling outputs. In this research, a method is designed to analyze and express climate data in a format that can be readily used to assess future extreme precipitation events in models commonly used for sizing stormwater infrastructure and identifying flooding potential. In this method, future conditions climate data are analyzed to prepare precipitation maps for selected design storm frequencies which can be used to model future climate conditions of stormwater runoff and flood risk. This report presents a newly designed research framework to determine future conditions rainfall frequency maps, illustrating it in Cook County, Illinois, for the 24-hour duration rainfall event and for a range of recurrence intervals (also called return periods). Engineers commonly use these maps to determine the appropriate return period rainfall amount by interpolating between the isohyetals to evaluate options for storm and flood water management. Impacts of future climate conditions can then be convincingly demonstrated using conventional engineering to show changes in flooding frequency and extent, as well as damage comparisons associated with changing intense precipitation. Using standard and familiar models with future conditions precipitation scenarios facilitates communication of quantifiable future risk and supports community decision makers so they can plan, mitigate, and adapt to future conditions. This directly supports climate adaptation and mitigation by providing an understandable method for community engineers and planners to demonstrate the impact of climate change at the local level and develop specific adaptation strategies that will reduce future risk.published or submitted for publicationis peer reviewedOpe