Development of Streams Classification System for Nutrient Criteria in Illinois

USEPApublished or submitted for publicationis peer reviewe

Impacts of Urbanization and Climate Variability on Floods in Northeastern Illinois

Illinois-Indiana Sea GrantOpe

Detection and Predictability of Spatial and Temporal Patterns and Trends of Riverine Nutrient Loads in the Midwest

The deleterious effects of multiple stressors on global water resources have become more significant over the past few decades. Anthropogenic activities such as industrialization, urbanization, deforestation, and increased application of agricultural nutrients have led to a decline in overall quality of our aquatic environment. Additionally, these activities have increased greenhouse gas concentrations globally, warming the earth’s atmosphere and eventually having a detrimental effect on global water and energy balances. The global water cycle has been altered, leading to its overall intensification and an increase in frequency of extreme floods and droughts. Addressing increasing water demands coupled with declining water quality and a depletion of water resources requires new approaches in water management. In determining optimum management actions, it is critical to understand the spatial and temporal variability and trends in water quantity and quality. This research aims to improve our knowledge of anthropogenic and natural impacts on water resources by evaluating and refining the science of predicting pollutant (nutrient and sediment) loadings from medium- to large-scale watersheds. To enable these goals, this research is centered on large watersheds in the Midwestern United States, which have been some of the primary sources of nutrient and sediment loadings to downstream water bodies such as the Gulf of Mexico and Lake Erie. In total, 14 watersheds in Illinois, Indiana, Ohio, and Michigan, with extensive water quality datasets, are analyzed in different stages of this research. Most of these watersheds are predominantly agricultural with intensive row-cropped farmlands and have a network of sub-surface tile drainage systems. Pollutant loadings and associated hydrological processes have been simulated using four major modeling approaches: statistical modeling, empirical modeling, physically based modeling, and data mining methods. This report includes eight chapters. The first three chapters describe the problem and research objectives, study area, and data preparation and processing. Next, the impacts of available water quality data on concentration and load predictions and trend calculations are assessed based on traditional statistical methods and several new, improved, and modified approaches (Chapter 4). This segment emphasizes the difficulties in predicting nutrient load and concentration trends under changing climatic conditions, highlighting the importance of continuous nutrient monitoring. Next, two data mining techniques (the nearest-neighbor method and decision trees), scarcely used in hydrology, were applied to predict the missing Nitrate Nitrogen (NO3-N) concentrations for two extensively monitored watersheds in the Lake Erie basin. These predictions (Chapter 5) are important in load estimations and demonstrate the potential of data mining to produce results comparable with statistical and empirical methods presented in the previous chapter. In Chapter 6, statistical regression techniques are used to assess the role of large load events in predicting Total Suspended Solids (SS), Total Phosphorus (TP), and NO3-N annual loads. A novel constituent-specific baseflow separation technique based on mechanistic differences in nutrient and sediment loadings is proposed and applied. As a result, regression relationships between the largest annual loads and total annual loads were developed for all three constituents. An Analysis of Covariance (ANCOVA) indicated that these relationships are often statistically indistinguishable from each other when applied to watersheds with a similar land use. Then, in Chapter 7, the temporal patterns of pollutant loadings from large Midwestern watersheds are analyzed using circular statistics. Critical periods of high loadings, precipitation, and river flow were identified. While river flows and pollutant loadings are highest in late winter and early spring (e.g., March and April), rainfall totals are highest during late spring and early summer (e.g., May through August). Finally, Chapter 8 shows the results based on the physically based SWAT model. The model is calibrated for river discharge and water quality in the largest watershed in the Lake Erie basin, the Maumee River watershed. The calibrated model is used to gauge the impacts of future projected climate change from the mid-century and late-century time periods on the hydrology and water quality in the watershed. The results indicate that climate change could have a significant impact on sediment and nutrient loads, and that more detailed studies are needed to more accurately assess this impact and its confidence limits.published or submitted for publicationis peer reviewedOpe

Hydrologic and Nutrient Monitoring of the Lake Decatur Watershed: Final Report 1993-2008

Lake Decatur is the water supply reservoir for the City of Decatur. The reservoir was created in 1922 by constructing a dam to impound the flow of the Sangamon River. The dam was modified in 1956 to increase the maximum capacity of the lake to 28,000 acre-feet. The lake receives water from the 925-square-mile watershed of the Upper Sangamon River which includes portions of seven counties in east-central Illinois. Lake Decatur has high nitrate-N concentrations which have been consistently exceeding the Illinois Environmental Protection Agency (IEPA) drinking water standard of 10 milligrams per liter (mg/L) since 1980. This has created a serious situation for the drinking water supply of the City of Decatur, since nitratenitrogen (N) cannot be removed from finished drinking water through regular water purification processes. Since 1993, the Illinois State Water Survey (ISWS) has been monitoring the Lake Decatur watershed for trends in discharge, nitrate-N concentration, and nitrate-N yield and to identify any significant changes in the watershed. The purpose of the monitoring was to collect reliable scientific data throughout the watershed for use by city planners and resource managers to develop watershed management alternatives based on scientific data. The ISWS originally established eight monitoring stations in the Upper Sangamon River watershed. Three of those stations have been in continuous operation from May 1993 to April 2008. A companion study funded by the Agricultural Watershed Institute allowed for continued monitoring at those three stations from May 2008 through September 2008. The purpose of this report is to document and present the discharge, nitrate-N concentration, and nitrate-N yield data for the 15 water years of monitoring (October 1993–September 2008), as well as to determine any annual trends in the Lake Decatur watershed. The intended purpose of the monitoring data and trends investigation results is to assist the City of Decatur planners and resource managers in developing watershed management alternatives to manage the current and future city water supply. In summary, eight of the 15 water years experienced above or extremely above normal precipitation. Based on the 100-year streamflow record at the Monticello station, 4 of the top 11 total annual discharges occurred during the monitoring period (Water Year (WY) 1993 - 2nd, WY2008 - 3rd, WY1994 - 10th, and WY1998 - 11th), whereas WY2000 had the fourth lowest annual discharge. The 15-year mean annual nitrate-N yield delivered to Lake Decatur from the Upper Sangamon River watershed was 23 lb/acre and varied from 6 lb/acre (WY2000) to 42 lb/acre (WY2008). During the 15-year monitoring period, there were no significant trends in discharge and nitrate-N yields for the Long Creek (101), Friends Creek (102), and Monticello (111) stations in the Lake Decatur watershed. Annual average nitrate-N concentration for the Monticello (111) station had a statistically significant increasing trend with an increase of 0.087 mg/L per year based on the statistical fit of the annual average data. This dataset was augmented by a longer data record (WY1975–2006) from the downstream gaging station near Oakford to investigate longer-term trends in the Sangamon River watershed. There were no trends detected for nitrate-N concentration or yield within the 32-year record from the Oakford gage.published or submitted for publicationis peer reviewe

Extreme Floods and Droughts under Future Climate Scenarios

Hydroclimatic extremes, such as floods and droughts, affect aspects of our lives and the environment including energy, hydropower, agriculture, transportation, urban life, and human health and safety. Climate studies indicate that the risk of increased flooding and/or more severe droughts will be higher in the future than today, causing increased fatalities, environmental degradation, and economic losses. Using a suite of innovative approaches this book quantifies the changes in projected hydroclimatic extremes and illustrates their impacts in several locations in North America, Asia, and Europe

Frequency Distributions of Heavy Precipitation in Illinois: Updated Bulletin 70

This study was designed to update the Illinois State Water Survey (ISWS) Bulletin 70,evaluating rainfall frequency relations in Illinois using current precipitation datasets. The studyprimarily used the National Oceanic and Atmospheric Administration (NOAA) daily precipitationdata from 1948 to 2017 to perform regional frequency analysis (RFA) using the L-momentsapproach. Additional information on precipitation relationships for less than 24 hours wereobtained from NOAA hourly precipitation data from 1948 to 2014 and Cook CountyPrecipitation Network (CCPN) data from 1989 to 2016. Precipitation frequency relations weredeveloped for storm durations from 1 to 240 hours and for recurrence intervals from 2 to 500years. The results are presented for the same 10 geographic sections as in Bulletin 70 (Figure 1) to maintain the continuity of hydrologic studies and compatibility with regulations.Illinois Department of Commerce and Economic Opportunitypublished or submitted for publicationis peer reviewedOpe

Frequency Distributions of Heavy Precipitation in Illinois: Spatio-Temporal Analyses (Revised)

Originally released 2019-12-11, revision published 2020-3-31This report provides new, updated precipitation frequencies for 10 regions in Illinois for event durations ranging from 5 minutes to 10 days (240 hours) and for recurrence intervals ranging from 2 months to 500 years. New, updated time-distribution characteristics of rainfall events, known as “Huff curves,” are also provided. The precipitation frequency estimates and their time distributions presented in this bulletin supersede those published in Bulletin 70, Circular 172, and Circular 173.Ope

Monitoring and Modeling of Nutrient & Sediment Loads for Varying Climate & Landscapes

Presentation on ISWS watershed data collection with examples from the Illinois River & Kaskaskia River Basins, monitoring for long-term sediment trends, and application of data for better modeling. Covers the Watershed Management Tool (WMT) and statistical modeling for the development of short-and long-term nutrient predictions.Ope

Prediction of weekly nitrate-N fluctuations in a small agricultural watershed in Illinois

Agricultural nonpoint source pollution has been identified as one of the leading causes of surface water quality impairment in the United States. Such an impact is important, particularly in predominantly agricultural areas, where application of agricultural fertilizers often results in excessive nitrate levels in streams and rivers. When nitrate concentration in a public water supply reaches or exceeds drinking water standards, costly measures such as well closure or water treatment have to be considered. Thus, having accurate nitrate-N predictions is critical in making correct and timely management decisions. This study applied a set of data mining tools to predict weekly nitrate-N concentrations at a gauging station on the Sangamon River near Decatur, Illinois. The data mining tools used in this study included artificial neural networks, evolutionary polynomial regression and the naive Bayes model. The results were compared using seven forecast measures. In general, all models performed reasonably well, but not all achieved best scores in each of the measures, suggesting that a multi-tool approach is needed. In addition to improving forecast accuracy compared with previous studies, the tools described in this study demonstrated potential for application in error analysis, input selection and ranking of explanatory variables, thereby designing cost-effective monitoring networks

Precipitation Frequency Study for Illinois

Storm frequency estimates and their temporal distributions are important in determining estimates of runoff or peak flow rates in many engineering and hydrological problems. Illinois State Water Survey (ISWS) Bulletin 70 (Huff and Angel, 1989a) has been serving as the design rainfall standard in Illinois since its publication in 1989 (IDOT, 2011). In addition, Illinois state agencies adopted ISWS Circular 172 (Huff and Angel, 1989b) and ISWS Circular 173 (Huff, 1990). Circular 172 provided some updates to Bulletin 70, and Circular 173 provided standard temporal distributions of rainfall events, known as Huff curves. These standards are best described in Circular 173, “This document provides the best available information on the time-distribution characteristics of heavy rainstorms at a point and on small basins encompassing areas of up to 400 square miles in Illinois and the Midwest. It is recommended for use in conjunction with Illinois State Water Survey Bulletin 70 (Huff and Angel, 1989a) and Circular 172 (Huff and Angel, 1989b) for runoff computations related to the design and operation of runoff control structures.” Although Bulletin 70, Circular 172, and Circular 173 represented the best available data at the time of their publication, they needed to be reevaluated and updated after more than three decades of using these standards. An additional 34 years of monitoring data has become available, and the growing evidence of the nonstationary nature of heavy precipitation events indicated that more frequent evaluations of precipitation frequency estimates are needed to capture changes in heavy precipitation (Winters et al., 2015). This report provides new, updated precipitation frequencies for 10 regions in Illinois for event durations ranging from 5 minutes to 10 days (240 hours) and for recurrence intervals ranging from 2 months to 500 years. New, updated time-distribution characteristics of rainfall events, known as “Huff curves,” are also provided. The precipitation frequency estimates and their time distributions presented in this bulletin supersede those published in Bulletin 70, Circular 172, and Circular 173.Ope