Geology topics

Timothy R. Lathrop

Publications and source records attributed to Timothy R. Lathrop.

6 recordsLinked to original sources

USGS2021

Regression models for estimating sediment, nutrient concentrations and loads at School Branch at Brownsburg, Indiana, June 2015 through February 2019

Sediment and nutrient transport in the School Branch watershed (in central Indiana west of Indianapolis) is considered to be heavily affected by agricultural land use throughout the watershed. In 2015, the U.S. Geological Survey, in cooperation with the Indiana Department of Environmental Management, deployed continuous water-quality monitors and began collecting discrete water-quality samples at the streamflow-gaging station School Branch at CR750N at Brownsburg, Indiana (U.S. Geological Survey station 03353420). Regression models that estimate concentrations of suspended sediment, total nitrogen, and total phosphorus were developed by relating streamflow and continuously monitored water-quality data to concentrations measured in discrete water-quality samples collected from June 2015 through February 2019. Regression model diagnostics indicated that streamflow and sensor-measured turbidity concentrations explained about 95 percent of the variation in suspended-sediment concentration and 73 percent of the variation in total phosphorus concentration. Similarly, streamflow and sensor-measured nitrate plus nitrite concentrations explained about 97 percent of the variation in total nitrogen concentrations. Daily loads of suspended sediment, total nitrogen, and total phosphorus were computed from regression model concentrations and instantaneous streamflow. The estimated mean daily suspended-sediment discharge (June 2015 through February 2019) was 1.184 tons per day; the estimated median suspended-sediment discharge was 0.053 tons per day. The estimated mean daily total nitrogen discharge (June 2015 through February 2019) was 127.50 pounds per day; the estimated median total nitrogen discharge was 28.49 pounds per day. The estimated mean daily total phosphorus discharge (June 2015 through February 2019) was 12.08 pounds per day; the estimated median total-phosphorus discharge was 1.208 pounds per day.

Indiana↗

USGS2019

Regression models for estimating sediment and nutrient concentrations and loads at the Iroquois River near Foresman, Indiana, March 2015 through July 2018

In 2015, the U.S. Geological Survey, in cooperation with the Iroquois River Conservancy District, deployed continuous water-quality monitors and began collecting representative discrete water-quality samples at the Iroquois River near Foresman, Indiana, streamflow-gaging station (U.S. Geological Survey station 05524500). By relating continuously monitored water-quality data and discrete water-quality samples collected from April 2015 through July 2018, regression models that estimate concentrations of suspended sediment, total nitrogen, and total phosphorus were developed. Developed regression models indicated a strong correlation between turbidity and streamflow with suspended-sediment concentration (adjusted coefficient of determination equals 0.84, predicted residual error sum of squares equals 0.493), nitrate plus nitrite and streamflow with total nitrogen (adjusted coefficient of determination equals 0.99, predicted residual error sum of squares equals 0.0202), and specific conductance and turbidity with total phosphorus (adjusted coefficient of determination equals 0.84, predicted residual error sum of squares equals 0.0935). Daily loads of suspended sediment, total nitrogen, and total phosphorus were computed as the product of daily mean regression model concentrations and daily mean streamflow. During periods when regression model concentrations could not be computed, rloadest models, the R programming language version of the LOADEST FORTRAN program, were used to compute daily loads of each constituent. For 2016 and 2017, the estimated annual suspended-sediment loads were 25,000 and 32,100 tons; estimated total nitrogen loads were 4,260 and 5,780 tons; and estimated total phosphorus loads were 104 and 128 tons, respectively.

Indiana↗

USGS2019

Regression models for estimating sediment and nutrient concentrations and loads at the Kankakee River, Shelby, Indiana, December 2015 through May 2018

The Kankakee River in northern Indiana flows through the area once known as the Grand Marsh. Beginning in the 1860s, anthropogenic changes to the river within Indiana resulted in downstream flooding and additional transport of sediment and nutrients. In 2015, the U.S. Geological Survey, in cooperation with the Indiana Department of Environmental Management, upgraded the gaging station Kankakee River at Shelby, Indiana, to include the collection of water-quality data. By relating continuously monitored water-quality data to discrete data collected from December 2015 through May 2018, linear regression was used to develop models for estimating concentrations of suspended sediment, total nitrogen, and total phosphorus. Developed regression models indicated a strong correlation between turbidity and specific conductance with suspended-sediment concentration (adjusted coefficient of determination equals 0.92, predicted residual error sum of squares equals 0.151), nitrate plus nitrite and specific conductance with total nitrogen (adjusted coefficient of determination equals 0.95, predicted residual error sum of squares equals 0.0248), and turbidity with total phosphorus (adjusted coefficient of determination equals 0.89, predicted residual error sum of squares equals 0.0103). Daily loads of suspended sediment, total nitrogen, and total phosphorus were computed as the product of daily mean regression model concentrations and daily mean streamflow. Rloadest models were used to compute daily loads of each constituent during gaps in regression model loads. For 2016 and 2017, the estimated annual suspended-sediment loads were 105,000 and 91,000 tons; estimated total nitrogen loads were 8,690 and 8,890 tons; and estimated total phosphorus loads were 265 and 236 tons, respectively.

Indiana↗

USGS2015

Real-time, continuous water-quality monitoring in Indiana and Kentucky

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 Indiana and Kentucky. A super gage includes streamflow and water-quality instrumentation and representative stream sample collection for laboratory analysis. USGS scientists can use statistical surrogate models to relate instrument values to analyzed chemical concentrations at a super gage. Real-time, continuous and laboratory-analyzed concentration and load data are publicly accessible on USGS Web pages.

Indiana, Kentucky↗

USGS2006

Agricultural Chemicals in Leary Weber Ditch Basin, Hancock County, Indiana, 2003-04

Leary Weber Ditch Basin, Hancock County, Indiana, is part of an Agricultural Chemicals: Source, Transport, and Fate study conducted by the National Water-Quality Assessment Program of the U.S. Geological Survey. Water-quality samples were collected in Leary Weber Ditch and in the major hydrologic compartments of the Leary Weber Ditch Basin during 2003 and 2004. Hydrologic compartments that contribute water and agricultural chemicals to Leary Weber Ditch are rain water, overland-flow water, soil water, tile-drain water, and ground water. Samples were analyzed for selected pesticides, nutrients, and major ions.

Indiana↗

USGS2006

Environmental Setting of the Sugar Creek and Leary Weber Ditch Basins, Indiana, 2002-04

The Leary Weber Ditch Basin is nested within the Sugar Creek Basin in central Indiana. These basins make up one of the five study sites in the Nation selected for the Agricultural Chemicals: Sources, Transport, and Fate topical study, a part of the U.S. Geological Survey’s National Water-Quality Assessment Program. In this topical study, identifying the natural factors and human influences affecting water quality in the Leary Weber Ditch and Sugar Creek Basins are the focus of the assessment. A detailed comparison between the environmental settings of these basins is presented. Specifics of the topical study design as implemented in the Leary Weber Ditch and Sugar Creek Basins are described. The Leary Weber Ditch and Sugar Creek Basins have moderate temperatures with well-defined winter and summer seasons. The mean annual precipitation is 39.5 inches, with the majority of rainfall in spring and early summer and the lowest amount of precipitation in winter. Yearly, an average of 25 inches of moisture moves into the atmosphere as a result of evapotranspiration. Physiographically, both basins are contained completely within the New Castle Till Plains and Drainageways. The gradients of the valleys of Leary Weber Ditch and Sugar Creek differ substantially. Most of the Sugar Creek Basin and the entire Leary Weber Ditch Basin overlie a combination of Devonian limestone and dolomite bedrock. Unconsolidated materials (sand and gravel) overlie much of the bedrock in the basins. Soils are either loam or silt loam, generally deep, poorly drained, medium textured, and nearly level. The potential for surface erosion is negligible because runoff is slow. Available water capacity is high. Natural fertility and organic matter are moderate. Soils are naturally suited to row crops. Agriculture is the principal land use in the Leary Weber Ditch and Sugar Creek Basins. Respectively, 87 percent and 75 percent of the total land area in these basins are used for row crops. The cropped areas within the basins are divided nearly equally between corn and soybeans. Farming practices in the area employ a wide range of tools to promote growth and inhibit vegetative competition; these include the use of fertilizers, herbicides, and pesticides. Tile drains are used extensively to improve yields and make the soils farmable. Irrigation and manure application in the study area are minimal. Most of the study area is in Hancock County, Indiana. The county population is approximately 61,000. There are no large cities in either basin; most residents live in small communities or rural areas. Water use in Hancock County totalled 6.37 million gallons per day during 2002. Drinking water comes entirely from ground water. The U.S. Geological Survey operates streamflow-gaging stations at Sugar Creek at New Palestine and at Leary Weber Ditch at Mohawk within the study area. Mean daily streamflow for Sugar Creek is higher than streamflow at Leary Weber Ditch. Through most of its length, Sugar Creek is a gaining stream and base flow is supported by ground-water sources. At Leary Weber Ditch, there is little to no streamflow when tile drains are dry. Modifications to the natural hydrology of the study area include a large system of tile drains, the intersection of Sugar Creek by several major roads, and outflows from nearby wastewater-treatment plants. Leary Weber Ditch is affected only by tile drains.

Indiana↗