Biweekly and total irrigation amounts and irrigation scheduling practices were monitored at representative sites in central Illinois during the 1988 and 1989 growing seasons. The purpose was to gather baseline information on average quantities of irrigation water used in normal and drought years and on the general efficiency of irrigation operations in the subhumid climate of Illinois. Soil water-holding capacity is the most important factor in determining irrigation amounts, explaining about 65 percent of the variability in irrigation totals. Other important factors in explaining irrigation variations include weather changes, individual farmer idiosyncrasies, and crop differences. In general, irrigation farmers in Illinois appear to be applying appropriate amounts of irrigation water at appropriate times in the growing season, based on their soil type, crop type, and total evaporative losses.
This report documents the structure and the use of a windows-based interface developed by the Illinois State Water Survey for the Office of Water Resources, Illinois Department of Natural Resources. The current version of the interface program is able to download historic, real-time, and forecasted stage and flow data from the U.S. Geological Survey, U.S. Army Corps of Engineers, and the National Weather Service websites interactively. These data are used to update existing Data Storage System (DSS) database or to create new ones; to run the UNET model for historic, design, real-time, and forecasted flood events in the Lower Illinois River; and to post-process model outputs from DSS files in tabular and graphical formats.. This interface program uses the original UNET generic geometry and boundary condition files to maintain the same level of accuracy as the UNET model, but it also allows the user to change some of the parameters, such as, the simulation time interval, time windows, and numerical Corant number, and etc., in the BC file. The real-time simulation of a flood event simulates the flood stage profiles using forecasted stage and real-time flow data downloaded from related websites. With the primary focus on simulations of levee failures, the interface program lets the users modify parameters to simulate simple levee failures through the simple spillway approach for two types of complicated embankment failures, overtopping and piping. A new simulation can be performed using the modified levee information. The change of water surface elevation induced by modifying the levees can be compared with another simulation graphically and also in table format. Stage profiles from all the simulations can be plotted together with the levee heights on both sides of the channel along the Lower Illinois River to provide a visual view of the locations of overtopping. Overtopping locations and magnitudes will be tabulated should they occur.
The practical application of selected analytical methods to well and aquifer evaluation problems in Illinois is described in this report. The subject matter includes formulas and methods used to quantitatively appraise the geohydrologic parameters affecting the water-yielding capacity of wells and aquifers and formulas and methods used to quantitatively appraise the response of wells and aquifers to heavy pumping. Numerous illustrative examples of analyses based on actual field data are presented. The aquifer test is one of the most useful tools available to hydrologists. Analysis of aquifer test data to determine the hydraulic properties of aquifers and confining beds under nonleaky artesian, leaky artesian, water table, partial penetration, and geohydrologic boundary conditions is discussed and limitations of various methods of analysis are reviewed. Hydraulic properties also are estimated with specific-capacity data and maps of the water table or piezometric surface. The role of individual units of multiunit aquifers is appraised by statistical analysis of specific capacity data. The influence of geohydrologic boundaries on the yields of wells and aquifers is determined by means of the image-well theory. The image-well theory is applied to multiple boundary conditions by taking into consideration successive reflections on the boundaries. Several methods for evaluating recharge rates involving flow-net analysis and hydrologic and groundwater budgets are described in detail. Well loss in production wells is appraised with step-drawdown test data, and well screens and artificial packs are designed based on the mechanical analysis of the aquifer. Optimum well spacings are estimated taking into consideration aquifer characteristics and economics. Emphasis is placed on the quantitative evaluation of the practical sustained yields of wells and aquifers by available analytical methods. The actual groundwater condition is simulated by a model aquifer having straight-line boundaries, an effective width, length, and thickness, and sometimes a confining bed with an effective thickness. The hydraulic properties of the model aquifer and its confining bed, if present, the image-well theory, and appropriate groundwater formulas are used to construct a mathematical model that provides a means of evaluating the performance of wells and aquifers. Records of past pumpage and water levels establish the validity of this mechanism as a model of the response of an aquifer to heavy pumping.
Two August 2002 rainstorms, one centered in Illinois and Indiana on August 18-19, and one in Iowa, Illinois, and Wisconsin on August 21-22, created record-setting point rainfalls of >10 inches and >12 inches, respectively. Return intervals of both storms' heavy rain amounts for 3-, 6-, and 12- hour durations exceeded once in 100-year values. Storm characteristics were similar to those of 36 past rainstorms during 1951-2001 that also were investigated in comparable detail. The similarities included the fact that most of the rain fell over 8 hours at night, storm areas were oriented west-east, and the region with >2 inches covered more than 9,000 square miles. Synoptically, conditions were similar to those of most past rainstorms: the storms developed south of an west-east-oriented front, precipitable water values were exceptionally high, >1.7 inches, and the frontal position and low-level jet stream proximity led to training of thunderstorms along the same path. However, the August 2002 rainstorms were different than past rainstorms in that the two storm events occurred just 2.5 days apart and in relatively adjacent areas. No other major past storms had occurred in such close time proximity. Both storms occurred where the prior 2.5-month rainfall was much below normal, creating much below normal soil moisture and droughtlike conditions for crops. All 36 previous major assessed rainstorms occurred after prolonged periods of average to much above average rainfall. This pre-storm difference in moisture conditions greatly affected the storms' impacts, and both August storms produced small economic losses compared to those of comparable prior storms. A much greater percentage of total storm rainfall infiltrated the soil, resulting in less runoff. High early peak flows in rivers where the heaviest rain fell quickly returned to normal levels within 10-22 days. Flooding, mostly near river courses, quickly dissipated, and flood losses were minimal. The major economic impact of the two August storms related to the added soil moisture and, in turn, the positive effects on soybean crops. Soybeans were in the pod-filling stage and shy of soil moisture when the storms occurred, and the rain-filled soils led to increased yields valued at $51 million in Illinois and Iowa.
This report documents the progress that has been made to date on the Conservation Reserve Enhancement Program (CREP) monitoring project. The Illinois Department of Natural Resources (IDNR) through the CREP provides support for this project. This monitoring program collects hydrologic, sediment, and nutrient data for selected watersheds within the Illinois River watershed to assist in the evaluation of the effectiveness of the program. The Illinois River CREP is a new initiative by the State of Illinois and the United States Department of Agriculture to implement conservation practices in the Illinois River watershed over a 15-year period that improve water quality and habitat for wildlife. Monitoring programs were established for sediment and nutrients for two pairs of watersheds within the Illinois River basin to collect hydrologic, sediment, and nutrient data during the implementation phase of the project. The two pairs of watersheds are the Court and Haw Creek watersheds (Spoon River basin) and the Panther-Cox Creek watershed (Sangamon River basin). This report details the location, equipment, and installation techniques used at the five monitoring stations and associated raingages that were installed as part of the data collection effort for this project. Samples of the data collection format and frequency are presented and described. Stage, nutrient concentration, and suspended sediment concentrations for data collected through June 2000 are also presented as appendices.
As a result of increased pollutant loading and low in-stream velocities, dissolved oxygen (DO) levels in the Chicago waterways historically have been low. In 1984, the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) issued a feasibility report on a new concept of artificial aeration referred to as sidestream elevated pool aeration (SEPA). The SEPA station concept involves pumping a portion of water from a stream into an elevated pool. The water is then aerated by flowing over a series of cascades or waterfalls, returning to the stream. The MWRDGC proceeded with design criteria for SEPA stations as a result of experimental work performed by the Illinois State Water Survey (ISWS). Five SEPA stations were constructed and placed in operation along the Calumet River, Little Calumet River, and the Cal-Sag Channel waterway. In 1995 the ISWS returned to conduct research to evaluate the reaeration efficiencies and their effects on in-stream DO. Continuous monitoring of DO, temperature, pH, and conductivity was performed at 14 locations along the Calumet and Little Calumet Rivers, Cal-Sag Channel, and Chicago Sanitary and Ship Canal to evaluate the effectiveness of the SEPA stations on maintaining in-stream DO concentrations. Also, supplemental cross-sectional measurements were made at the 14 locations and at an additional seven locations. Comparisons of mass balance, completely mixed, in-stream mean DO concentrations at the SEPA station outfalls and those measured at cross-sectional stations immediately downstream of each SEPA station were made. Results showed that each SEPA station has an immediate positive impact on in-stream DO concentrations. At SEPA stations 1 and 2, where the impacts are small, the positive effects can best be demonstrated using completely mixed values. Two important conclusions can be made. One is that the SEPA stations, particularly stations 3, 4, and 5, are fulfilling the intended function of maintaining stream DO standards in the Calumet and Little Calumet Rivers and the Cal-Sag Channel. The second is that DO concentrations less than the DO standard are still observed in the Chicago Sanitary and Ship Canal in the reach beginning above its juncture with the Cal-Sag Channel to the Lockport Lock and Dam. Over the entire study period, DO concentrations were maintained above the standard 98.6 percent of the time from the SEPA station 3 outfall to the intake of SEPA station 4 and 97.5 percent of the time from the outfall of SEPA station 4 to the intake of EPA station 5. Significant improvements in DO concentrations were also achieved for at least 4 miles downstream of SEPA station 5 in the Chicago Sanitary and Ship Canal.
The Illinois State Water Survey (ISWS) conducted sedimentation surveys of Lake Paradise and Lake Mattoon during 2001 in support of an Illinois Clean Lakes Program diagnostic/feasibility study to provide information on the storage and sedimentation conditions of the lakes. Both lakes are owned and operated by the City of Mattoon, which withdraws water from Lake Paradise as the raw water source for distribution of finished water and generally uses withdrawals from Lake Mattoon to maintain a more stable water level in Lake Paradise. The village of Neoga also withdraws water from Lake Mattoon for treatment and distribution. Since June 2001, Reliant Energy has operated a peaker power plant that has withdrawn water from Lake Mattoon for cooling systems. Lake Paradise and Lake Mattoon are located on the main stem of the Little Wabash River, a tributary to the Wabash River. The watershed is a portion of Hydrologic Unit 05120114. The dam for Lake Paradise is about 4 miles southwest of the City of Mattoon at 39 24' 47" north latitude and 88 26' 23" west longitude in Section 8, Township 11N., Range 7E., Coles County. The dam for Lake Mattoon is about 12 miles southwest of the City of Mattoon at 39 20' 00" north latitude and 88 28' 56" west longitude in Section 1, Township 10N., Range 6E., Shelby County.Lake Paradise was surveyed in 1979 and Lake Mattoon in 1980 as part of a previous cooperative study by the ISWS, the Illinois Department of Transportation - Division of Water Resources (DoWR), the Illinois Water Resources Center, and several departments at the University of Illinois at Urbana-Champaign. Lake Paradise lost 835 acre-feet (ac-ft) of its capacity as a result of sedimentation between 1908 and 2001. Approximately 481 ac-ft of this loss has occurred since 1931, which gives an annual sedimentation rate of 9.9 ac-ft since 1931. If this rate of sedimentation continues, the volume of Paradise Lake will be approximately half of the potential 1908 volume in the year 2013 and will be filled completely by sediment in the year 2118. Lake Mattoon lost 1,705 ac-ft of its 1958 capacity as a result of sedimentation between 1958 and 2001, a sedimentation rate of 39.7 ac-ft per year since 1958.If this rate of sedimentation continues, the volume of Lake Mattoon will be approximately half of the 1958 capacity by 2124 and will be completely filled in the year 2291. The sedimentation rates for Lake Paradise and its watershed for the periods 1931-1979, 1979-2001, and 1931-2001 were stable and ranged from 9.5 to 10 ac-ft.The long-term average annual sediment yield from 1931-2001 was 9.85 ac-ft. These sedimentation rates correspond to a rate of loss of lake capacity of 0.51 percent per year (1931-2001). The sedimentation rates for Lake Mattoon and its watershed for the periods 1958-1980, 1980-2001, and 1958-2001 indicate a reduction in net sediment yield from 66.9 ac-ft per year for 1958-1980 to 10.7 ac-ft per year (1980-2001).The long-term average annual sediment yield was 39.5 ac-ft (1958-2001). These sedimentation rates correspond to rates of loss of lake capacity of 0.51 percent per year (1958-1980) and 0.08 percent per year (1980-2001).The long-term average sedimentation rate for the lake is 0.30 percent per year (1958-2001).
Brochure describes the Illinois State Water Survey (ISWS), which has been a leader in the study of water resources for more than a century. Founded in 1895, its original mission was to survey the waters of Illinois to trace the spread of waterborne disease, ensure health and safety of public water supplies, improve wastewater treatment, and help develop sanitary standards for drinking water. The mission and scope have expanded to include varied scientific research and service programs relating to water and atmospheric resources of interest to Illinois.
One of the main concerns was the ability to specify proper stage hydrographs at the downstream boundary of the Lower Illinois River for hydraulic design and analysis. We found that a unique stage-discharge rating relationship does not exist at the lower boundary of the Lower Illinois River at Grafton because of backwater effects from the Upper Mississippi River. Management options and results for managed storage and emergency activities need to be analyzed under more comprehensive design of flooding conditions. To improve the capability of UNET for modeling backwater effects for the Lower Illinois River, an extended model including Pool 26 of the Upper Mississippi River was developed. The downstream stations of the model are at the tail of Lock and Dam 25 and the Mel Price Lock and Dam pool, where stage readings are available. The model was calibrated with a 1979 flood and verified with a 1983 flood. Discharge and stage frequency analysis have also been performed for stations at Troy on Cuivre River, Lock and Dam 25 tail, Lock and Dam 26 pool, and Mel Price Lock and Dam on the Mississippi River.
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.