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Electronic Documents of Illinois

The Electronic Documents of Illinois provides permanent public access to official publications of the State of Illinois which have been deposited in electronic form.

Creator Organization: Illinois State Library

Showing 3721 - 3730 of +10000 Records

Effective discharges of Illinois streams

Part of: Electronic Documents of Illinois

The hydrologic regime of a natural stream is usually highly complex and encompasses a wide range of discharges. The magnitudes and frequencies at which the various discharges occur play a key role in creating the channel's morphology. The concept of 'dominant discharge' proposes that there exists a single steady discharge that, theoretically, if constantly maintained in a stream over a long period of time would form and maintain the same basic stable channel dimensions as those produced by the long-term natural hydrograph. This theoretical discharge is referred to as a stream's dominant discharge. If such a dominant discharge exists and can be accurately calculated, this discharge can be one of the tools that stream restoration personnel use to help design channels that are morphologically stable, i.e., not experiencing either excessive erosion or sediment deposition. There is no direct method to calculate a stream's dominant discharge, and stream researchers have commonly assumed that the dominant discharge can be equated with either the stream's bankfull discharge, a specific flood recurrence interval, or the stream's effective discharge. The purpose of this study is to analyze the available data and existing computational methods for the third approach, that being the estimation of effective discharges specific to Illinois streams. The effective discharge of a stream is defined as the single discharge rate that carries the most sediment over time. Note that the effective discharge is not typically a discharge associated with the most extreme flood events, which may carry large amounts of sediment load but occur infrequently. Instead it is commonly considered to be a moderately high discharge having a more modest load, but occurring frequently enough that in the long-run it carries more sediment than the extreme flood events. To facilitate computations, the effective discharge is estimated as occurring within a discharge class or increment, rather than as a single discharge. Effective discharge can be estimated using data on suspended sediment load, bed load, bed material, or total sediment load, with the method of estimation depending on the sediment transport characteristics of the stream, available data, and, to some degree, the researcher's school of thought. For this study, estimates of effective discharges are based on the suspended sediment load, which is the dominant load in most Illinois streams. Suspended sediment data collected at 88 gaging stations within Illinois were analyzed to determine which gaging stations in Illinois currently have sufficient suspended sediment data available to estimate effective discharges. A procedure was adapted from previous research and implemented to compute effective discharge values for each stream location having sufficient suspended sediment data. For each of those gaging stations, an estimate was made of the flow frequency at which the effective discharge was equaled or exceeded. For stations having adequate sediment data, flood recurrence intervals associated with effective discharge values were computed using annual maximum flow data. Correlation coefficients (r2) for 12 linear regressions are presented to describe the relationship between six effective discharge parameters and channel slope and watershed area. The data from 20 of the 88 gaging stations were deemed sufficient for computing effective discharge values. These 20 gaging stations were located on streams with watershed areas ranging from 244 to 6363 square miles (mi2). The relatively large watershed areas allow use of mean daily discharge values in computing effective discharge values. The annual maximum series analysis indicated that recurrence intervals associated with effective discharges found at these stations ranged from less than 1.01 years to 1.23 years. Such recurrence intervals are on the low end of the 1- to 3-year recurrence intervals commonly reported in other studies. However, these recurrence intervals are representative of Illinois' larger watersheds, and recurrence intervals of effective discharges in smaller Illinois watersheds could be quite different. Of the 20 qualified stations, 20 percent had effective discharge estimates that were less than the station's average mean daily discharge. Such low magnitude flow events are not usually associated with a stream's dominant discharge. Thus, geomorphic assessments and bankfull computations are required to further assess whether these and other effective discharge values are representative of the 20 individual streams' dominant discharges. Due to the small sample size, regression analyses relating specific effective discharge parameters to channel slope and watershed area were inconclusive. Effective discharge computations are particularly sensitive to how the sediment rating curve used in the computation is developed and the number of discharge classes used in the computation. The sampling frequency and duration over which the sediment samples used to create sediment rating curves also may influence effective discharge computations significantly. Thus, while stream restoration personnel will likely continue to use these and other effective discharge values as part of several tools in hydraulic and channel design applications, uncertainties in their use should be acknowledged and undue weight should not be assigned these values, as they cannot yet be expected to yield fully reliable results in applications. Like previous researchers, we recommend more comprehensive investigations that compare effective discharge estimates to bankfull discharges in combination with a geomorphic assessment of each stream's characteristics to yield a better understanding of whether currently computed effective discharge values adequately represent dominant discharges in Illinois. Suspended sediment represents the dominant sediment load in most Illinois streams. In some cases, effective discharge computations based on total loads or bed material loads may be more appropriate than using suspended sediment loads analyzed here. However, the bed load, bed material, bank material, local channel slope, and channel cross-section information required to perform these computations and analyses are almost nonexistent. While many of these data can be collected at selected stream locations, inherent difficulties in estimating bed loads in Illinois streams make this approach unfeasible. New technologies for sampling or estimating bed load most likely would need to be developed and tested. This analysis presents a comprehensive assessment of effective discharges based on the available suspended sediment and flow data in Illinois. Long-term sediment data sets are needed at more stream locations to more fully estimate and understand effective and dominant discharges in Illinois streams. The greatest need for additional data is for smaller watersheds less than approximately 200 mi2 because most potential applications of the effective discharge concept in stable channel design are for smaller watersheds. Smaller watersheds also may have significantly different geomorphic characteristics and effective discharges may behave differently than those in larger watersheds. The Illinois State Water Survey currently is measuring suspended sediment at gaging stations on 13 small watersheds, which could prove very useful in effective discharge analysis as longer data records become available at these sites.

Date Created:
2004-09-24

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Embarras River watershed digital floodplain mapping, Champaign County, Illinois

Part of: Electronic Documents of 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.

Date Created:
2005-09-07

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Environmental Education Resources for Teachers

Part of: Electronic Documents of Illinois

Environmental education covers a broad range of topics from recycling and pollution to natural resources and wildlife. Environmental education programs target all ages from preschool children to graduate students. This guide focuses on resources for teaching K-12 students about the environmental effects of pollution and waste and strategies for improving the environment. It also includes some industrial chemistry resources. This reference guide includes links to classroom activities, background and policy information, standards, and reference sources that teachers can use to develop their own environmental education lesson plans. Because the scope of the topic is so broad, this is not meant to be an exhaustive list. Rather, it is designed to give you some places to start looking for resources. Information to help you continue your research at your local library is included at the end of the guide.

Date Created:
2001-06-01

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Eclipse v. United States Compliance Company

Part of: Electronic Documents of Illinois

Nos. 2--06--0825 and 2--06--0889 cons. Filed: 11-30-07 in the Appellate Court Of Illinois Second District, ECLIPSE MANUFACTURING COMPANY, an Illinois Corporation, Individually and on Behalf of Members of a Certified Class, as Assignee, Plaintiff and Third-Party Citation Petitioner-Appellee and Cross-Appellant, v. UNITED STATES COMPLIANCE COMPANY, d/b/a United States Compliance Corporation, a Minnesota Corporation, Defendant (Hartford Casualty Insurance Company, an Indiana Corporation, Third-Party Citation Respondent-Appellant and Cross-Appellee). Appeal from the Circuit Court of Lake County. No. 03--CH--922 Honorable Michael J. Fritz, Judge, Presiding.

Date Created:
2007-11-30

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Economic Opportunity

Part of: Electronic Documents of Illinois

Through our E-newsletter, we'll share new programs that are being developed, as well as changes to our programs and success stories. This issues articles are Cahokia Restoration Fund A Reality, New Law Provides Crucial Protections to Payday Loan Consumers, Hidden Lake Winery, Aviston, IL, Financial Resource Guide for Illinois Women and Illinois Commemorative Medallion Program.

Date Created:
2005-11-21

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Eastern Illinois University. Financial Audit for the year ended June 30, 2006

Part of: Electronic Documents of Illinois

State of Illinois Eastern Illinois University Financial Audit For The Year Ended June 30, 2006

Date Created:
2007-01-17

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Miniature of East St. Louis Financial Advisory Authority. Financial Audit for the year ended June 30, 2006, Compliance Examination for the two years ended June 30, 2006

East St. Louis Financial Advisory Authority. Financial Audit for the year ended June 30, 2006, Compliance Examination for the two years ended June 30, 2006

Part of: Electronic Documents of Illinois

State Of Illinois East St. Louis Financial Advisory Authority Financial Audit For The Year Ended June 30, 2006 Compliance Examination For the Two Years Ended June 30, 2006

Date Created:
2007-03-22

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EDI Depositor

Part of: Electronic Documents of Illinois

Information on the Illinois State Library's Electronic Documents Initiative, EDI. This issue includes items about training sessions, writing document descriptions, copy and paste from a PDF file, archiving responsibilities in the Illinois Administrative Code, agencies trained in March and library services for State employees.

Date Created:
2007-03-28

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EDI Depositor

Part of: Electronic Documents of Illinois

Information on the Illinois State Library's Electronic Documents Initiative, EDI, for those who are depositing state documents in electronic format. This issue announces training, discusses choosing subject headings and reports on the growth of EDI.

Date Created:
2007-10-11

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Economic Opportunity

Part of: Electronic Documents of Illinois

Through our E-newsletter, we'll share new programs that are being developed, as well as changes to our programs and success stories. Inside this issue: SBA Record Year, SIUC Office of Economic and Regional Development, Bright Start, Small Business Rebounds, Current Banking Trends and Smart Women Smart Money Conferences.

Date Created:
2006-10-18

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Electronic Documents of Illinois

Showing 3721 - 3730 of +10000 Records

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