Organization | • | Illinois State Water Survey | [X] |
| | | | Title: | | | | | Volume/Number: | 1992 | | | | Issuing Agency: | | | | | Description: | The purpose of this study was to use models to simulate the effect of the Stratton Dam operation, and possible structural modifications such as the addition of Foster gates, on flood stages and discharges in the Fox River and the Fox Chain of Lakes. The hydraulics and hydrology of Stratton Dam, the Fox River, and the Chain of Lakes were simulated for a wide range of historical flooding conditions and potential operation schemes. Responses for many different major flood conditions were analyzed, but two particular aspects of flood control were given special attention: 1) increasing outflow from the lakes in anticipation of a major flood, and 2) facilitating the flow release of the lakes by adding Foster gates at Stratton Dam and downstream at Algonquin Dam. This information will provide the IDOT-DWR with information for implementing possible modifications to the Stratton Dam operation during flood conditions. | | | | Date Created: | 9 24 2004 | | | | Agency ID: | CR-533 | | | | ISL ID: | 000000000794 Original UID: 999999993570 FIRST WORD: Effect | |
| | | Title: | | | | | Volume/Number: | 2002 | | | | Issuing Agency: | | | | | Description: | 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: | 9 24 2004 | | | | Agency ID: | CR-2002-10 | | | | ISL ID: | 000000000871 Original UID: 999999994348 FIRST WORD: Effective | |
| | | Title: | | | | | Volume/Number: | 2002 | | | | Issuing Agency: | | | | | Description: | Riparian forests have been proposed by the Technical Advisory Subcommittee of the Upper Embarras River Basin Commission in its alternatives for mitigating flood damages in the Village of Villa Grove and nearby farmlands. In order to evaluate potential reduction in flood stages in Villa Grove, methods for accounting for flow resistances induced by the riparian forests are needed in the hydraulic model for the Upper Embarras River. This project has been designed to better apply the available knowledge in practical field applications, particularly, how to evaluate the vegetal roughness in terms of Manning's andlt;EMandgt;nandlt;/EMandgt; coefficient for specified planting scenarios. Approaches presented in this report are literature review on Manning's roughness with emphasis on vegetative roughness, and evaluation and selection of methods for computing vegetative roughness due to riparian forests. The Petryk and Bosmajian (1975) method was selected for evaluating Manning's andlt;EMandgt;nandlt;/EMandgt; for mature trees because parameters could be reasonably obtained with available general field information. Using this approach, effects of riparian forest on floods were evaluated with the scenarios that the two-year floodplain has two densities of trees. The study reach was the channel between Villa Grove and Camargo. Also investigated were the options of having uniform tree density for the whole reach or half of the reach. An interface has been developed for implementing the computed andlt;EMandgt;nandlt;/EMandgt; values to a HEC-RAS hydraulic model, and capacity curves were developed to illustrate the effects on flood conveyance among these scenarios. The capacity curves thoroughly included possible boundary conditions and were presented in simple nomographs that relate discharge and downstream elevations to a specified flood elevation in Villa Grove. Therefore it was easier to evaluate the resulting effects of different alternatives. | | | | Date Created: | 9 24 2004 | | | | Agency ID: | CR-2002-02 | | | | ISL ID: | 000000000861 Original UID: 999999994341 FIRST WORD: Effects | |
| | | Title: | | | | | Volume/Number: | 2000 | | | | Issuing Agency: | | | | | Description: | An anomalously warm El Nio event developed in the eastern tropical Pacific Ocean during May-August 1997. El Nio events have become recognized as capable of having major effects on atmospheric circulation patterns over North America and elsewhere, leading to predictable outcomes for future seasonal weather conditions. The source of the nation's official long-range predictions, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC), began issuing forecasts in May 1997 about the event's development and growth to near record proportions. The emerging El Nio was expected to match or exceed the El Nio of 1982-1983, the strongest of this century. Predictions of the future weather conditions expected over the nation, as a result of El Nio's influence on the atmosphere, also were issued by CPC beginning in June 1997. Basically, these and subsequent predictions called for a fall, winter, and early spring in the Midwest that would have above normal temperatures and below normal precipitation. The predictions also called for storms and precipitation to increase in other parts of the nation, particularly in the South and West Coast areas. Media and wide public interest in the evolving record event brought inquiries to the Midwestern Climate Center (MCC) during June 1997. At that time, MCC leadership launched special studies and efforts related to the El Nio event, which included: a climatological reanalysis of past El Nio events and the associated weather conditions in the Midwest, the issuance of outlooks based on these studies, and the collection and analysis of data on the impacts caused by the El Nio-generated weather conditions in the Midwest. This decision was in keeping with past MCC research policy that has focused on assessing extreme Midwestern weather conditions like the 1988 drought (Changnon, 1991a and b), the 1993 flood (Kunkel, 1996; Changnon, 1996), and the 1995 heat wave (Kunkel et al., 1996; Changnon et al., 1996). These studies also focused on identifying and quantifying the impacts of these extreme events. The findings of such activities help the MCC respond rapidly and accurately to numerous regional inquiries for data and information about such extreme events. They also help the MCC prepare for effectively addressing similar events in the future. During the El Nio event, beginning in June 1997 and ending in May 1998, the MCC scientists issued several climate outlooks about future Midwestern conditions. These were basically probabilistic-based statements and focused on the winter of 1997-1998, spring 1998, and summer 1998 outcomes. During the El Nio event, the MCC staff collected and recorded all the relevant weather data for the Midwest. Data defining the impacts of El Nio-generated weather events were collected from August 1997 through August 1998. This report presents information about MCC activities related to El Nio in 1997-1998. It includes three sections: the predictive outlooks issued, a climatic assessment of monthly and seasonal weather conditions during the event, and a description of societal and economic impacts caused in the Midwest. Recommendations are offered in the section "Conclusions and Recommendations" for addressing future El Nio events and the handling of long-range predictions. | | | | Date Created: | 9 24 2004 | | | | Agency ID: | DCS-2000-01 | | | | ISL ID: | 000000000893 Original UID: 999999994304 FIRST WORD: El | |
| | | Title: | | | | | Volume/Number: | 2002 | | | | Issuing Agency: | | | | | Description: | 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: | 9 7 2005 | | | | Agency ID: | CR-2002-05 | | | | ISL ID: | 000000000863 Original UID: 999999994343 FIRST WORD: Embarras | |
| | | Title: | | | | | Volume/Number: | 2006 | | | | Issuing Agency: | | | | | Description: | This study evaluated the use of radar-derived daily precipitation values for estimating watershed precipitation in the Fox River watershed in northeastern Illinois and southeastern Wisconsin, and for the potential use in preparing real-time streamflow forecasts for the Fox River. Two types of radar-derived precipitation estimates based on data from the National Weather Service (NWS) WSR-88D radar network were evaluated. These estimates were developed using a 4-km grid resolution and computed using: 1) radar data alone and 2) composite or multi-sensor precipitation estimate based on radar data and real-time hourly precipitation gage observations. These gridded precipitation estimates were obtained from the National Center for Environmental Prediction (NCEP) and were compared to point measurements of daily precipitation from precipitation gages in the vicinity of the Fox River watershed for the period February 2002-September 2004. Multi-sensor precipitation estimates were found to be a considerable improvement over the gridded radar estimates during all seasons. In comparison to the daily gage data, however, the multi-sensor precipitation estimates were on average 25 percent lower throughout the year. Multi-sensor daily precipitation estimates from four storm periods were input to the Fox River Forecast Model to evaluate their potential application in hydrologic forecasting. Only one storm event produced flooding conditions on the Fox River in the period for which radar data was available. The remaining three storm events analyzed in this report produced only moderately high flows. Simulated flow forecasts using the multi-sensor precipitation values were less accurate than companion forecasts using observed data from precipitation gages. Based on the limited number and size of storm events available for simulation, this study was unable to conclude whether or not the multi-sensor precipitation values would be useful for forecasting floods. Until more comparisons can be conducted using data from future major flood events, flow forecasts for the Fox River should continue to be developed using near real-time data from precipitation gages. The present tendency of the multi-sensor precipitation data to underestimate rainfall amounts also makes their use generally inappropriate for longer term hydrologic simulations. | | | | Date Created: | 5 30 2006 | | | | Agency ID: | CR-2006-05 | | | | ISL ID: | 000000000906 Original UID: 999999994481 FIRST WORD: Evaluation | |
| | | Title: | | | | | Volume/Number: | 2003 | | | | Issuing Agency: | | | | | Description: | The Illinois Streamflow Gaging Network has been operated by the U.S. Geological Survey (USGS) since the early 1900s. From its inception, the operation of the network has been maintained through a cooperative partnership between the USGS and state and federal agencies. Hydrologic information provided by the network is vital for the general management of Illinois' water resources. Streamflow data are continually used for forecasting floods and droughts; assessing the biological and chemical health of our streams; operating reservoirs, water supply facilities, wastewater treatment facilities, and hydroelectric plants; assessing and predicting the long-term impacts of climate and land-use trends on our streams; and numerous other important uses. The purpose of this study was to conduct a comprehensive evaluation of the use of Illinois streamflow data, with the goal that this information and analysis will be used by the network's cooperating agencies and others for current and future decisions related to funding and content of the network. Evaluations such as this have been conducted in the past, and should continue to be conducted periodically to assess whether the network meets the data needs of users in an effective manner, to assess emerging needs, and to anticipate needed programmatic changes to the network. This report identifies several emerging applications for which more and additional types of stream data likely will be needed, including applications related to stream and watershed restoration and water quality load assessment. However, in general, it is not possible to anticipate many of the future needs of the streamflow gaging program. More often than not, emerging issues will need to use streamflow data far before there is sufficient time to collect data for that specific use. The only way to have adequate data when these needs arise is to maintain a base network at locations that are representative of the streams of Illinois, such that these long-term data are available to meet a broad range of potential needs. This base network of gaging stations also is needed to provide general streamflow information for ungaged streams throughout Illinois. There are thousands of streams in Illinois, whereas the network currently includes roughly 160 continuous-streamflow gages on fewer than 110 of these streams. For other streams, flow characteristics must be estimated from the available gaging records using regional hydrologic principles. Various methods are available to evaluate the effectiveness of specific gaging records for use in this regional transfer of information. This report includes several descriptive measures of the regional value of gage information and also summarizes a numerical evaluation based on information transfer theory. No single approach can effectively describe the broad range of considerations needed to evaluate the regional value of gages. However, it is clear that applications in regional hydrology will need additional data beyond those which are currently supported by the network. Specifically, the base network is noticeably lacking data from small watersheds in rural Illinois. In addition, several hydrologic regions in Illinois have a limited number of gages for use in regional analysis. Two questionnaires were developed to ascertain the importance and uses of the data from the streamflow gaging network. The first questionnaire was distributed to all agencies that provide cooperative funding to the network. The second questionnaire was developed on an Internet Web site to be accessed and filled out by all interested users of Illinois streamflow data. In both questionnaires, the respondents were asked to identify: 1) the types of data that they most frequently use and/or are most critical for their needs; 2) categories of data applications and their relative importance; and 3) the importance of specific gages for their applications. The report provides a ranking of the relative importance of individual gages based on the responses from the questionnaires. The users indicate that river forecasting/flood warning is the overall most important category of application of streamflow data, followed by long-term flow statistics for analyzing hydrologic trends and determining human impacts to streams. However, the majority of users are more likely to use streamflow data for individual project needs such as those related to hydrologic-hydraulic modeling and design, and biological and conservation assessment. Analysis of gaging records indicates that streamflow conditions are not stationary, and vary not only from year to year but also from decade to decade as influenced by climate variability and other factors. More than half of the long-term flow records in rural areas show statistically significant increases in average and low-flow conditions that appear to occur as a result of climate variability. Statewide, over the past 25 years, there has also been an average increase of 18 percent in the estimates of the 100-year flood peak discharge as represented by long-term records. With the decline in the number of crest-stage peak-flow gages and small watershed gages, many of the records available for certain types of hydrologic analysis are older, discontinued gaging records that may not accurately represent the expected present-day, long-term hydrologic conditions. Shorter gaging records, regardless of period of record, also may not fully represent the expected long-term conditions. There is a need for analytical techniques to assess inherent differences in streamflow records and characteristics such as flood frequency that are caused by climatic variability and other factors. The network appears to be meeting most traditional current-use needs. However, there is a need to reinforce the base network, specifically regarding data for relatively small rural watersheds that are needed to address various emerging issues, long-term regional assessment, and peak flood estimation. The size of the overall network would have to be increased an additional 15-20 percent to more effectively address data needs related to small to medium-sized rural watersheds. Also, there is a growing need for new types of stream data to address specific biological and conservation issues such as stream and watershed restoration. This report only addresses streamgaging issues related to flow quantity, and thus there are no conclusions or recommendations related to water quality, precipitation, or other types of hydrologic data. Funding for the Illinois Streamflow Gaging Network is subject to uncertainties, and this is especially the case regarding potential growth or changes to the network. The National Streamflow Information Program (NSIP), initiated by the USGS in 1999, proposed that the USGS eventually would assume the costs of gages that directly meet specific federal interests. However, it is uncertain whether this or other initiatives from traditional funding sources will produce a prominent change in the size and character of the network. More likely, gaging needs for emerging issues will need to be funded from new sources currently not participating in the network. By its nature, it is essential that the base network be funded mainly through state or federal agencies with a long-term commitment to the streamflow gaging program. | | | | Date Created: | 9 24 2004 | | | | Agency ID: | CR-2003-05 | | | | ISL ID: | 000000000872 Original UID: 999999994401 FIRST WORD: Evaluation | |
| | | Title: | | | | | Volume/Number: | 2006 | | | | Issuing Agency: | | | | | Description: | Solar power production was estimated from hourly solar insolation data collected at 19 sites across Illinois from 1991-2004 by the Illinois State Water Survey (ISWS). Values were compared with more limited, experimental data and a solar radiation model reported in the literature. All prior data sources are in good agreement with the ISWS values with discrepancies noted. Based on analyses of the current Illinois data, an estimate was made of potential power production from small to medium-sized photovoltaic modules and systems in Illinois. ISWS insolation data were converted from observed values using flat-plate pyramometers oriented horizontally, to expected values from south-facing sensors tilted from horizontal by the latitude of each station, a typical orientation of photovoltaic systems. Champaign, Illinois, centrally located in the state, was chosen as a hypothetical solar power array site. A large operational array in Arizona was used as a model of photovoltaic system performance. Expected differences in power production due to technologies chosen for the hypothetical array and climatological conditions in Illinois as compared to the model array were considered. The use of concentrated solar collectors was not explored. The expected power output based on two array designs was calculated to be 134-180 kilowatt hours per square meter of array per year. Considering the unsubsidized cost of a photovoltaic array necessary to provide power for an individual dwelling, the system cannot expect to match grid power on a cost basis at this time. However, the comparison becomes more favorable in relatively remote locations where transmission lines for grid connection must be established. That is, photovoltaics may be cost effective for small remote applications such as powering billboards, but generally not for homes or businesses. Cost effectiveness of photovoltaics increases significantly when major subsidies and economy-of-scale discounts in both module and balance-of-system costs are available to reduce the initial system price and with designs of large-scale array systems. Photovoltaics also may be worth considering to offset the most expensive power produced by utilities, peak power, and for distributed power generation providing grid support. | | | | Date Created: | 8 17 2006 | | | | Agency ID: | IEM-2006-05 | | | | ISL ID: | 000000000946 Original UID: 999999994488 FIRST WORD: Evaluation | |
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