A statewide study was performed to develop regional regression equations for estimating selected annual exceedance-probability statistics for ungaged stream sites in Iowa. The study area comprises streamgages located within Iowa and 50 miles beyond the State’s borders. Annual exceedance-probability estimates were computed for 518 streamgages by using the expected moments algorithm to fit a Pearson Type III distribution to the logarithms of annual peak discharges for each streamgage using annual peak-discharge data through 2010. The estimation of the selected statistics included a Bayesian weighted least-squares/generalized least-squares regression analysis to update regional skew coefficients for the 518 streamgages. Low-outlier and historic information were incorporated into the annual exceedance-probability analyses, and a generalized Grubbs-Beck test was used to detect multiple potentially influential low flows. Also, geographic information system software was used to measure 59 selected basin characteristics for each streamgage.
Regional regression analysis, using generalized least-squares regression, was used to develop a set of equations for each flood region in Iowa for estimating discharges for ungaged stream sites with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities, which are equivalent to annual flood-frequency recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively. A total of 394 streamgages were included in the development of regional regression equations for three flood regions (regions 1, 2, and 3) that were defined for Iowa based on landform regions and soil regions.
The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources, used the Soil and Water Assessment Tool to simulate streamflow and nitrate loads within the Cedar River Basin, Iowa. The goal was to assess the ability of the Soil and Water Assessment Tool to estimate streamflow and nitrate loads in gaged and ungaged basins in Iowa. The Cedar River Basin model uses measured streamflow data from 12 U.S. Geological Survey streamflow-gaging stations for hydrology calibration. The U.S. Geological Survey software program, Load Estimator, was used to estimate annual and monthly nitrate loads based on measured nitrate concentrations and streamflow data from three Iowa Department of Natural Resources Storage and Retrieval/Water Quality Exchange stations, located throughout the basin, for nitrate load calibration. The hydrology of the model was calibrated for the period of January 1, 2000, to December 31, 2004, and validated for the period of January 1, 2005, to December 31, 2010.
In this study, Lagrangian sampling, in which the same approximate parcel of water is tracked as it moves downstream, was conducted at Boulder Creek, Colorado and Fourmile Creek, Iowa to determine in-stream transport and attenuation of more than 200 organic contaminants (including metal complexing agents, nonionic surfactant degradates, personal care products, pharmaceuticals, steroidal hormones, and pesticides) discharged from two secondary WWTPs. Similar stream reaches were evaluated, and samples were collected at multiple sites during summer and spring hydrologic conditions. After accounting for in-stream dilution, a complex mixture of contaminants showed little attenuation and was persistent in the receiving streams at concentrations with potential ecosystem implications.
The concentrations of electron donors and sediment propoerties of aquifer sediments near the South Fork Iowa River were conducted on 50 samples collected from below the water table in 11 boreholes. Samples were analyzed for gravel, sand (coarse, medium, and fine), silt, clay, Munsell soil color, inorganic carbon content, and for the following electron donors: organic carbon, ferrous iron, and inorganic sulfide. Sediment mineralogy was analyzed by using x-ray diffraction (XRD)
Water quality was characterized near the mouths of 10 major Iowa tributaries to the Mississippi and Missouri Rivers from March 2004 through September 2008. Stream loads were calculated for select ions, nutrients, and sediment. Concentrations and loads in Iowa streams vary seasonally with streamflow, and are spatially related to the landform. Studied streams had a combined basin area of 50,562 square miles, covering 75 percent of Iowa. Relative to statewide fertilizer application, transport from the 10 streams studied ranged from 8 to 56 percent for nitrogen and 1.0 to 11.1 percent for phosphorus.
The U.S. Geological Survey (USGS) maintains approximately 148 real-time streamgages in Iowa for which daily mean streamflow information is available, but daily mean streamflow data commonly are needed at locations where no streamgages are present. Therefore, the USGS conducted a study as part of a larger project in cooperation with the Iowa Department of Natural Resources to develop methods to estimate daily mean streamflow at locations in ungaged watersheds in Iowa by using two regression-based statistical methods.
This report provides a description of the watershed, the thunderstorms, the flooding, and a profile of high-water marks measured at 20 locations along the South Skunk River.
The U.S. Geological Survey's Environmental Health Newsletter
The GeoHealth Newsletter provides information on new USGS environmental health science activities related to safeguarding the health of the environment, fish and wildlife, domesticated animals, and people. The Newsletter is issued twice a year.
Current Issue: Vol. 9, No. 3, 2012
A permanent link to the GeoHealth Newsletter has been created on the left side of this webpage under IA WSC Links.
The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources, conducted a study to examine techniques for estimation of daily streamflows using hydrological models and statistical methods. This report focuses on the use of a hydrologic model, the U.S. Geological Survey.s Precipitation-Runoff Modeling System, to estimate daily streamflows at gaged and ungaged locations. The Precipitation-Runoff Modeling System is a modular, physically based, distributed-parameter modeling system developed to evaluate the impacts of various combinations of precipitation, climate, and land use on surface-water runoff and general basin hydrology. The Cedar River Basin was selected to construct a Precipitation-Runoff Modeling System model that simulates the period from January 1, 2000, to December 31, 2010. The calibration period was from January 1, 2000, to December 31, 2004, and the validation periods were from January 1, 2005, to December 31, 2010 and January 1, 2000 to December 31, 2010.
Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, are described. Concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed transported a greater percentage of the applied herbicides; especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage.
A statewide study was conducted to develop regression equations for estimating six selected low-flow frequency statistics and harmonic mean flows for ungaged stream sites in Iowa. The estimation equations developed for the six low-flow frequency statistics include: the annual 1-, 7-, and 30-day mean low flows for a recurrence interval of 10 years, the annual 30-day mean low flow for a recurrence interval of 5 years, and the seasonal (October 1 through December 31) 1- and 7-day mean low flows for a recurrence interval of 10 years. Estimation equations also were developed for the harmonic-mean-flow statistic. Estimates of these seven selected statistics are provided for 208 U.S. Geological Survey continuous-record streamgages using data through September 30, 2006. The study area comprises streamgages located within Iowa and 50 miles beyond the State’s borders.
These regression equations will be implemented within the U.S. Geological Survey StreamStats web-based geographic-information-system tool. StreamStats allows users to click on any ungaged site on a river and compute estimates of the seven selected statistics; in addition, 90-percent prediction intervals and the measured basin characteristics for the ungaged sites also are provided. StreamStats also allows users to click on any streamgage in Iowa and estimates computed for these seven selected statistics are provided for the streamgage.
Hydrologist Dana Kolpin welcomed the new research, saying caffeine concentrations in water have been documented before but more often in freshwater than marine environments.
"Caffeine is pretty darn ubiquitous, and there is growing evidence that this and other understudied contaminants are out there," said Kolpin, of the USGS's Toxic Substances Hydrology Program in Iowa City, Iowa.
In our waste "there is a whole universe of potential contaminants including pharmaceuticals, hormones, personal-care products like detergents or fragrances, even artificial sweeteners."
Caffeine is something of a canary in a coal mine for elevated levels of human contaminants in water, said Kolpin, who wasn't part of the new study.
Effects upon microbial communities from environmental exposure to concentrations of antibiotics in the μg L–1 range remain poorly understood. Microbial communities from an oligotrophic aquifer (estimated doubling rates of only once per week) that were previously acclimated (AC) or unacclimated (UAC) to historical sulfamethoxazole (SMX) contamination, and a laboratory-grown Pseudomonas stutzeri strain, were exposed to 240–520 μg L–1 SMX for 30 days in situ using filter chambers allowing exposure to ambient groundwater, but not to ambient microorganisms. SMX-exposed UAC bacterial communities displayed the greatest mortality and impairment (viable stain assays), the greatest change in sensitivity to SMX (dose–response assays), and the greatest change in community composition (Terminal Restriction Fragment Length Polymorphism; T-RFLP). The sul1 gene, encoding resistance to SMX at clinically relevant levels, and an element of Class I integrons, was not detected in any community. Changes in microbial community structure and SMX resistance over a short experimental period in previously nonexposed, slow-growing aquifer communities suggest concentrations of antibiotics 2–3 orders of magnitude less than those used in clinical applications may influence ecological function through changes in community composition, and could promote antibiotic resistance through selection of naturally resistant bacteria.
Land application of biosolids (treated sewage sludge) can be an important route for introducing xenobiotic compounds into terrestrial environments. There is a paucity of available information on the effects of biosolids amendment on terrestrial organisms. In this study, the influence of biosolids and biosolids aging on earthworm (Eisenia fetida) reproduction and survival and lettuce (Lactuca sativa) seedling emergence was investigated. Earthworms were exposed to soils amended with varying quantities of biosolids (0, 1, 2, 3, or 4% dry mass). To investigate the influence of biosolids aging, the biosolids used in the study were aged for differing lengths of time (2 or 8 weeks) prior to exposure. All of the adult earthworms survived in the biosolids–amended soils at all concentrations that were aged for 2 weeks; however, only 20% of the adults survived in the soil amended with the highest concentration of biosolids and aged for 8 weeks. Reproduction as measured by mean number of juveniles and unhatched cocoons produced per treatment correlated inversely with biosolids concentration, although the effects were generally more pronounced in the 8-week aged biosolids–soil samples. Latent seedling emergence and reduced seedling fitness correlated inversely with biosolids concentration, but these effects were tempered in the 8-week aged versus the 2-week aged soil–biosolids mixtures. Anthropogenic waste indicator compounds (AWIs) were measured in the biosolids, biosolids–soil mixtures, and earthworm samples. Where possible, bioaccumulation factors (BAFs) were calculated or estimated. A wide variety of AWIs were detected in the biosolids (51 AWIs) and earthworm samples (≤ 19 AWI). The earthworms exposed to the 8-week aged biosolids–soil mixtures tended to accumulate greater quantities of AWIs compared to the 2-week aged mixture, suggesting that the bioavailability of some AWIs was enhanced with aging. The BAFs for a given AWI varied with treatment. Notably large BAFs were determined for some AWIs. For example, the maximum BAF determined for para-cresol, methyl salicylate, bisphenol-A, and cholesterol was greater than 100 in some treatments.
Learn About the Land: RAGBRAI 2012 Brochures
Once again, the USGS, Iowa Water Science Center, the IDNR Geological & Water Survey and the Iowa Limestone Producers have teamed up to provide the Learn About The Land daily trip logs describing interesting landscape, geologic, and other natural and historical features and resources along the RAGBRAI trail. Look for USGS volunteers as they distribute these brochures in the RAGBRAI campgrounds.
Click on each days brochure to learn more about the land of Iowa.
New this year - Learn About The Land-Casts are podcasts that provide information about what the bikers will be traversing - rivers, lakes, geology and landform regions. Be sure to check out Day 5 for more information about the U.S. Geological Survey.
This paper summarizes methodological advances in regional log-space skewness analyses that support flood-frequency analysis with the log Pearson Type III (LP3) distribution. A Bayesian Weighted Least Squares/Generalized Least Squares (B-WLS/B-GLS) methodology that relates observed skewness coefficient estimators to basin characteristics in conjunction with diagnostic statistics represents an extension of the previously developed B-GLS methodology. B-WLS/B-GLS has been shown to be effective in two California studies. B-WLS/B-GLS uses B-WLS to generate stable estimators of model parameters and B-GLS to estimate the precision of those B-WLS regression parameters, as well as the precision of the model. The study described here employs this methodology to develop a regional skewness model for the State of Iowa.
This report describes an assessment of groundwater quality of the Cambrian-Ordovician aquifer system across the upper Midwest, based primarily on raw water samples collected by the NAWQA Program from 1995 through 2007. An assessmentwas made for physical properties, major ions, trace elements, nutrients and dissolved organic carbon, radionuclides (tritium, radon, and radium), pesticides, and volatile organic compounds. The assessment objectives of this report are to (1) summarize constituent concentrations and compare them to human-health benchmarks and non-health guidelines; (2) determine the geographic distribution of constituent concentrations and relate them to various factors such as confining conditions, well type, land use, and groundwater age; and (3) evaluate near-decadal-scale changes in nitrate concentrations and pesticide detections.
Des Moines, Iowa is now better prepared to issue flood alerts because of enhancements to river monitoring equipment put in place by the City of Des Moines Department of Public Works and the U.S. Geological Survey.
Download this video as a: [.mp4 .m4v .webm]
General Circulation Model simulations of future climate through 2099 project a wide range of possible scenarios. To determine the sensitivity and potential effect of long-term climate change on the freshwater resources of the United States, the U.S. Geological Survey Global Change study, "An integrated watershed scale response to global change in selected basins across the United States" was started in 2008. The long-term goal of this national study is to provide the foundation for hydrologically based climate change studies across the nation.
Fourteen basins for which the Precipitation Runoff Modeling System has been calibrated and evaluated were selected as study sites. Precipitation Runoff Modeling System is a deterministic, distributed parameter watershed model developed to evaluate the effects of various combinations of precipitation, temperature, and land use on streamflow and general basin hydrology. Output from five General Circulation Model simulations and four emission scenarios were used to develop an ensemble of climate-change scenarios for each basin. These ensembles were simulated with the corresponding Precipitation Runoff Modeling System model. This fact sheet summarizes the hydrologic effect and sensitivity of the Precipitation Runoff Modeling System simulations to climate change for the Clear Creek Basin, near Coralville, Iowa.
A study by the U.S. Geological Survey (USGS) evaluated the hydrologic response to different projected carbon emission scenarios of the 21st century using a hydrologic simulation model. This study involved five major steps: (1) setup, calibrate and evaluated the Precipitation Runoff Modeling System (PRMS) model in 14 basins across the United States by local USGS personnel; (2) acquire selected simulated carbon emission scenarios from the World Climate Research Programme's Coupled Model Intercomparison Project; (3) statistical downscaling of these scenarios to create PRMS input files which reflect the future climatic conditions of these scenarios; (4) generate PRMS projections for the carbon emission scenarios for the 14 basins; and (5) analyze the modeled hydrologic response. This report presents an overview of this study, details of the methodology, results from the 14 basin simulations, and interpretation of these results.
A key finding is that the hydrological response of the different geographical regions of the United States to potential climate change may be different, depending on the dominant physical processes of that particular region. Also considered is the tremendous amount of uncertainty present in the carbon emission scenarios and how this uncertainty propagates through the hydrologic simulations.
The Cedar River alluvial aquifer is the primary source of municipal water in the Cedar Rapids, Iowa area. The City of Cedar Rapids and the U.S. Geological Survey have been conducting a cooperative study of the groundwater-flow system and water quality of the aquifer since 1992. Cooperative reports between the City of Cedar Rapids and the U.S. Geological Survey have documented hydrologic and water-quality data, geochemistry, and groundwater models. This report presents the results of water-quality analyses of routine quarterly samples from monitoring wells, municipal wells, and the Cedar River from January 2006 through December 2010. Water-quality data include major ions, nutrients, dissolved organic carbon, and selected pesticides including two degradates of the herbicide atrazine. Methods of data collection, quality-assurance, water-quality analyses, and statistical procedures are presented.
Studies of the transport and fate of agricultural chemicals in different environmental settings were conducted by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's Agricultural Chemicals Team (ACT) in the South Fork Iowa River basin in central Iowa and the Bogue Phalia basin in northwestern Mississippi. The South Fork Iowa River basin is representative of midwestern agriculture, where corn and soybeans are the predominant crops and a large percentage of the cultivated land is underlain by artificial drainage. The Bogue Phalia basin is representative of corn, soybean, cotton, and rice cropping in the humid, subtropical southeastern United States. Details of the environmental settings of these basins and the data-collection activities conducted during the 2006-10 study period are described in this report.
Exploration of Streamflow Changes at Decadal to Century Time Scales
Speaker: Dr Robert Hirsch, USGS Research Hydrologist
Time: Thursday March 8th, 2012 at 1:00PM
Location: Main floor of the Wallace Building in Des Moines (502 E 9th St). [Map]
The upper Midwest and eastern Prairies (Eastern North and South Dakota and Nebraska plus large parts of Minnesota and Iowa) have experienced very large and very persistent changes in streamflow conditions over the past 120 years. This presentation will use graphical approaches to time-series analysis to explore streamflow records from around this region: in terms of flood flows, average flows, and low flows. Questions considered include the role of long-term persistent behavior in the climate system (quasi-periodic oscillations), the role of land-use and land-drainage changes, and the role of human-enhanced greenhouse forcing. Results from this region are compared with other parts of the U.S., particularly other areas where snow plays a significant role in the hydrologic cycle. The recently published Hirsch and Ryberg study of nationwide flooding trends will also be described.
Robert Hirschs biography.
2011 proved to be a record-setting year for flooding in the central United States, with floods that extended from headwater streams in the Rocky Mountains, to trans-boundary rivers in the upper Midwest and North?rn Plains, to the deep and wide sand-bedded lower Mississippi River. The U.S. Geological Survey (USGS), as part of its mission, collected extensive information during and in the aftermath of the 2011 floods to support scientific analysis of the origins and consequences of extreme floods. The information collected for the 2011 floods, combined with decades of past data, enables scientists and engineers from the USGS to provide syntheses and scientific analyses to inform emer?ency managers, planners, and policy makers about life-safety, economic, and environmental-health issues surroundOng flood hazards for the 2011 floods and future floods like it.
Understanding the effects of climate change on the vegetative growing season is key to quantifying future hydrologic water budget conditions. The U.S. Geological Survey modeled changes in future growing season length at 14 basins across 11 states. The Clear Creek basin, 1 of the 14 basins in this study, was evaluated to examine the growing season length determined by emission scenario,as compared to a growing season length fixed baseline condition. The Clear Creek basin showed substantial variation in hydrologic responses, including streamflow, as a result of growing season length determined by emission scenario.
This report was part of a collection of similar studies that can be found at the American Meteorological Society's page, Integrated Watershed-Scale Response to Climate Change in Selected Basins across the United States.
Minor flooding occurred July 23, 2010, in the Little Maquoketa River Basin and major flooding occurred July 23-26, 2010, in the Maquoketa River Basin in northeast Iowa following severe thunderstorm activity over the region during July 22-24. A breach of the Lake Delhi Dam on July 24 aggravated flooding on the Maquoketa River. Rain gages at Manchester and Strawberry Point, Iowa, recorded 72-hour-rainfall amounts of 7.33 and 12.23 inches, respectively, on July 24. The majority of the rainfall occurred during a 48-hour period. Within the Little Maquoketa River Basin, a peak-discharge estimate of 19,000 cubic feet per second (annual flood-probability estimate of 4 to 10 percent) at the discontinued 05414500 Little Maquoketa River near Durango, Iowa streamgage on July 23 is the sixth largest flood on record.
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