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Greg Koltun

Greg is a hydrologist and surface-water specialist for the Ohio-Kentucky-Indiana Water Science Center.

He received a B.S. in microbiology and an M.S. in civil engineering from the Ohio State University and has worked on a wide array of research, including topics in hydrology, hydraulics, water quality, water use, modeling, and applied statistics. Greg teaches a USGS national training course on sediment and chemical loading computation methods and was an adjunct professor at the Ohio State University where he taught applied hydrology.

 

Science and Products

Filter Total Items: 48

Assessment of runoff volume reduction associated with soil amendments added to portions of highway median-strip catchments in Ohio, 2018–20

The U.S. Geological Survey installed 10 rain gages and 12 calibrated H-flumes to measure rainfall and runoff volumes at 10 locations in Ohio Department of Transportation highway median-strip catchments. Data were collected to facilitate comparisons of rainfall and runoff volumes at study sites before and after stormwater best management practices (BMPs) were installed and between sites with differ
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Ohio-Kentucky-Indiana Water Science Center

Estimated total phosphorus loads for selected sites on Great Lakes tributaries, water years 2014–2018

Monthly and annual total phosphorus loads were estimated for water years 2014 through 2018 for 23 streamgaged (gaged) sites on tributaries to the Great Lakes. Processing and regression methods described by Robertson and others (2018) were used with discrete and continuous data collected during water years 2011 and 2018 to update regression models for estimating instantaneous flux with the same for
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Ohio-Kentucky-Indiana Water Science Center

Trends in streamflow, nutrients, and total suspended solids in the Upper White River Basin, Indiana

The U.S. Geological Survey, in partnership with The Nature Conservancy, analyzed existing water-quality and streamflow data from three locations in the Upper White River Basin, Indiana, to estimate annual mean concentrations and fluxes and to identify and quantify changes in water quality and streamflow over time. Water-quality data used in the analyses were collected between water years 1992 and
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Ohio-Kentucky-Indiana Water Science Center

Trends in streamflow and concentrations and flux of nutrients and total suspended solids in the Upper White River at Muncie, near Nora, and near Centerton, Indiana

The U.S. Geological Survey (USGS), in cooperation with The Nature Conservancy, completed a study to estimate and assess trends in streamflow and annual mean concentrations and flux of nutrients (nitrate plus nitrite, total Kjeldahl nitrogen, and total phosphorus) and total suspended solids at three USGS streamgages (hereafter referred to as “study gages”) on the Upper White River at Muncie (USGS s
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Ohio-Kentucky-Indiana Water Science Center

Flood-frequency estimates for Ohio streamgages based on data through water year 2015 and techniques for estimating flood-frequency characteristics of rural, unregulated Ohio streams

Estimates of the magnitudes of annual peak streamflows with annual exceedance probabilities of 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002 (equivalent to recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years, respectively) were computed for 391 streamgages in Ohio and adjacent states based on data collected through the 2015 water year. The flood-frequency estimates were computed follow
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Ohio-Kentucky-Indiana Water Science Center

Geospatial tools effectively estimate nonexceedance probabilities of daily streamflow at ungauged and intermittently gauged locations in Ohio

Study regionThe state of Ohio in the United States, a humid, continental climate.Study focusThe estimation of nonexceedance probabilities of daily streamflows as an alternative means of establishing the relative magnitudes of streamflows associated with hydrologic and water-quality observations.New hydrological insights for the regionSeveral methods for estimating nonexceedance probabilities of da

Estimation of upstream water use with Ohio’s StreamStats application

This report describes the analytical methods and results of a pilot study to enhance the Ohio StreamStats application by adding the ability to obtain water-use information for selected areas in the northeast quadrant of Ohio. Water-use estimates are determined in StreamStats through a simple multistep process.  Water-use data used to develop the Ohio StreamStats water-use application were obtained
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Water Resources, Ohio-Kentucky-Indiana Water Science Center

Hydrologic and hydraulic analyses for the Black Fork Mohican River Basin in and near Shelby, Ohio

Hydrologic and hydraulic analyses were done for selected reaches of five streams in and near Shelby, Richland County, Ohio. The U.S. Geological Survey (USGS), in cooperation with the Muskingum Watershed Conservancy District, conducted these analyses on the Black Fork Mohican River and four tributaries: Seltzer Park Creek, Seltzer Park Tributary, Tuby Run, and West Branch. Drainage areas of the fou
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Water Resources, Ohio-Kentucky-Indiana Water Science Center

Hydrologic effects of potential changes in climate, water use, and land cover in the Upper Scioto River Basin, Ohio

This report presents the results of a study to provide information on the hydrologic effects of potential 21st-century changes in climate, water use, and land cover in the Upper Scioto River Basin, Ohio (from Circleville, Ohio, to the headwaters). A precipitation-runoff model, calibrated on the basis of historical climate and streamflow data, was used to simulate the effects of climate change on s
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Water Resources, Ohio-Kentucky-Indiana Water Science Center

An evaluation of the accuracy of modeled and computed streamflow time-series data for the Ohio River at Hannibal Lock and Dam and at a location upstream from Sardis, Ohio

Between July 2013 and June 2014, the U.S. Geological Survey (USGS) made 10 streamflow measurements on the Ohio River about 1.5 miles (mi) downstream from the Hannibal Lock and Dam (near Hannibal, Ohio) and 11 streamflow measurements near the USGS Sardis gage (station number 03114306) located approximately 2.4 mi upstream from Sardis, Ohio. The measurement results were used to assess the accuracy o
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Water Resources, Ohio-Kentucky-Indiana Water Science Center

An analysis of potential water availability from the Charles Mill, Clendening, Piedmont, Pleasant Hill, Senecaville, and Wills Creek Lakes in the Muskingum River Watershed, Ohio

This report presents the results of a study to assess potential water availability from the Charles Mill, Clendening, Piedmont, Pleasant Hill, Senecaville, and Wills Creek Lakes, located within the Muskingum River Watershed, Ohio. The assessment was based on the criterion that water withdrawals should not appreciably affect maintenance of recreation-season pool levels in current use. To facilitate
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Water Resources, Ohio-Kentucky-Indiana Water Science Center

GCLAS: a graphical constituent loading analysis system

The U. S. Geological Survey has developed a program called GCLAS (Graphical Constituent Loading Analysis System) to aid in the computation of daily constituent loads transported in stream flow. Due to the relative paucity with which most water-quality data are collected, computation of daily constituent loads is moderately to highly dependent on human interpretation of the relation between stream
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Water Resources
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Grand River near Painesville, OH - ice jam

Grand River near Painesville, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Ohio-Kentucky-Indiana Water Science Center
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Grand River near Painesville, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Huron River at Milan, OH

Huron River near Milan, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Ohio-Kentucky-Indiana Water Science Center
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Huron River near Milan, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Black River at Elyria, OH - bridge view

Black River at Elyria, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Ohio-Kentucky-Indiana Water Science Center
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Black River at Elyria, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Cuyahoga River at Independence OH - view from river bank

Cuyahoga River at Independence, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
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Ohio-Kentucky-Indiana Water Science Center
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Cuyahoga River at Independence, OH

Water-quality “super” gages (also known as “sentry” gages) provide real-time, continuous measurements of the physical and chemical characteristics of stream water at or near selected U.S. Geological Survey (USGS) streamgages in Ohio, Kentucky, and Indiana. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS...
Learn More

Dataset for Analyses in Assessment of Runoff Volume Reduction Associated with Soil Amendments Added to Portions of Highway Median-Strip Catchments in Ohio

Rainfall and runoff data were collected during non-winter months between 2018 and 2020 at 10 rain gages and 12 calibrated H-flumes located in Ohio Department of Transportation (ODOT) highway median-strip catchments. The data were used to compute event-based summary statistics of rainfall and runoff. A rainfall-runoff "event" was defined to begin at the time of the first measured rainfall
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Ohio-Kentucky-Indiana Water Science Center

Total suspended solids, total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen concentration data for the White River at Muncie, Indiana, 1991-2017

Data release contains total suspended solids, total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen concentration data for the White River at Muncie, near Nora, and near Centerton, Indiana, 1991-2017, and R source code used for model development.
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Ohio-Kentucky-Indiana Water Science Center

Geospatial Tools Effectively Estimate Nonexceedance Probabilities of Daily Streamflow at Ungaged and Intermittently Gaged Locations in Ohio: Data Release

This data set archives all inputs, outputs and scripts needed to reproduce the findings of W.H. Farmer and G.F. Koltun in the 2017 Journal of Hydrology Regional Studies article entitled Geospatial Tools Effectively Estimated Nonexceedance Probabilities of Daily Streamflow at Ungauged and Intermittently Gauged Locations in Ohio. Input data includes observed streamflow values, in cubic feet per seco
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Water Resources

Culvert Analysis Program (CAP) version 2021.0.0

The culvert analysis program (CAP) version 2021 updates and corrects know errors in standalone versions 98-07c or earlier and iRIC version 3.X or earlier.
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Ohio-Kentucky-Indiana Water Science Center

GCLAS (Graphical Constituent Loading Analysis System): A tool for computing loads of constituents transported in rivers

GCLAS is a program designed to compute daily and annual loadings of constituents transported in rivers. 

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Water Resources, Water Resources, Ohio-Kentucky-Indiana Water Science Center

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