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Branden L. VonIns

Publications and source records attributed to Branden L. VonIns.

4 recordsLinked to original sources
USGS2026

Flood-frequency estimates for Kentucky streamgages based on data through water year 2021 and results of updating the fundamental layers in Kentucky StreamStats

The U.S. Geological Survey, in cooperation with the Kentucky Transportation Cabinet, analyzed flood-frequency statistics for streamgages in Kentucky. Using annual peak-flow data through water year 2021, flood-frequency estimates were computed for 261 streamgages, including unregulated and regulated sites as well as sites with mixed regulation records. Methods followed those outlined in “Guidelines for Determining Flood Flow Frequency—Bulletin 17C” (U.S. Geological Survey Techniques and Methods 4–B5). These estimates included flows corresponding to annual exceedance probabilities of 50, 20, 10, 4, 2, 1, and 0.2 percent. Temporal trend analyses using the Mann-Kendall test indicated that 18 percent of unregulated streamgages with (1) at least 30 years of peak-flow record and (2) peak-flow record at least as recent as water year 2000 showed statistically significant trends, most of which were weak to moderate increases in peak flows. Concurrently, the fundamental geospatial datasets that support the Kentucky StreamStats application were updated by using high-resolution digital elevation models and hydrography datasets to derive flow direction, flow accumulation, and stream definition rasters. Comparisons of regression-based flood-frequency models using the old and new layers demonstrated consistent results, with a statewide root-mean-square error of 0.019, in the base-10 logarithm of cubic feet per second. Furthermore, to assess model performance, flood-frequency estimates made by using the updated layers and previously published regression-based models were compared to flood-frequency estimates newly computed by following Bulletin 17C. This analysis showed the models performed adequately for most Kentucky stream locations. The updated statistics and geospatial layers provide stakeholders with more accurate, current data for flood-risk assessment, infrastructure design, and water-resource management.

Kentucky↗
USGS2024

Low-flow statistics computed for streamflow gages and methods for estimating selected low-flow statistics for ungaged stream locations in Ohio, water years 1975–2020

A study was conducted by the U.S. Geological Survey, in cooperation with the Ohio Water Development Authority and the Ohio Environmental Protection Agency, to compute low-flow frequency, flow-duration, and harmonic mean flow statistics for long-term streamflow gages and to develop regression equations to estimate those statistics at unregulated, ungaged stream locations in Ohio. The flow statistics were computed with data collected after the 1974 water year because upward trends and statistically significant step changes (occurring after the late 1960s but before 1975) in annual flow statistics were detected at many candidate gages in Ohio. A total of 180 continuous-record gages in Ohio and bordering States were identified as having at least 10 years of daily flow records during the analytical period (water years 1975–2020). Also identified were five low-flow partial-record gages in Ohio that had instantaneous low flows that correlated strongly with daily streamflows at one of the continuous-record gages (also referred to as index gages). For continuous-record gages, the following flow statistics were computed: annual and seasonal minimum 1-, 7-, 30-, and 90-day flows with 2-, 5-, 10-, 20-, and 50-year recurrence intervals; annual and seasonal 98-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 20-, and 10-percent duration flows; and the harmonic mean flow. For partial-record gages, estimates were made for annual and seasonal minimum 1-, 7-, 30-, and 90-day low flows with 2-, 10-, and 20-year recurrence intervals and annual and seasonal 98-, 95-, 90-, 85-, and 80-percent duration flows. The drainage basin of each gage was inspected for anthropogenic or karst features that could appreciably affect or regulate low flows. That inspection resulted in data from 53 of the 180 continuous-record gages and the 5 low-flow partial-record gages being categorized as “unregulated” and subsequently used in regression analyses to develop equations for estimating low-flow statistics. Two hundred and sixty potential explanatory variables were tested for this study. In most cases, a streamflow-variability index (SVI) was chosen as the sole explanatory variable for the regression analyses to predict the harmonic mean and annual and seasonal low-flow yields. The exceptions were for one of the September–November low-flow yield statistics and all the December–February yield statistics. Drainage area, decimal longitude, and usually SVI were chosen as the explanatory variables for those exceptions and to predict the 80-percent duration flows. The SVI values used in the model were estimated from a geospatial grid of SVI values developed for this study by using an empirical Bayesian kriging regression prediction. Observations for continuous-record gages used in the regression analyses were weighted as a function of their record length. Weights for partial-record gages were estimated based on the weights determined for their index gages. Equations for low-flow yields were developed by using censored regressions with a censoring level of 0.00001 cubic foot per second per square mile. Numerical constraints were placed on the yield equations if they could compute yields less than the yield censoring level or if the yields did not monotonically decrease with increasing SVI. Logistic-regression equations were developed, with SVI and drainage area as explanatory variables, to estimate the probability that the low-flow statistics were greater than the flow censoring level (0.01 cubic foot per second). The regression equations presented in this report were developed for implementation in the Ohio StreamStats application. The equations are applicable to unregulated streams in Ohio and are not applicable to streams with karst drainage features, diversions, regulation, or other anthropogenic activities that can appreciably affect low flow. The equations were developed by using observations with a range of SVI values from 0.41 to 1.23 log10 cubic foot per second and a range of drainage areas from 0.21 to 540 square miles. The applicability of the equations outside these ranges is not known.

Ohio↗
USGS2017

Response of currents and water quality to changes in dam operations in Hoover Reservoir, Columbus, Ohio, August 24–28, 2015

Hoover Reservoir, an important drinking water supply for the City of Columbus, Ohio, has been the source of a series of taste and odor problems in treated drinking water during the past few years. These taste and odor problems were caused by the compounds geosmin and 2-methylisoborneol, which are thought to have been related to cyanobacteria blooms. In an effort to reduce the phosphorus available for cyanobacteria blooms at fall turnover, the City of Columbus began experimenting with the dam’s selective withdrawal system to remove excess phosphorus in the hypolimnion, which is released from bottom sediments during summer anoxic conditions. The U.S. Geological Survey completed two synoptic survey campaigns to assess distributions of water quality and water velocity in the lower part of Hoover Reservoir to provide information on the changes to reservoir dynamics caused by changing dam operations. One campaign (campaign 1) was done while water was being withdrawn from the reservoir through the dam’s middle gate and the other (campaign 2) while water was being withdrawn through the dam’s lower gate. Velocities were measured using an acoustic Doppler current profiler, and water-quality parameters were measured using an autonomous underwater vehicle equipped with water-quality sensors. Along with the water-quality and water-velocity data, meteorological, inflow and outflow discharges, and independent water-quality data were compiled to monitor changes in other parameters that affect reservoir behavior. Monthly nutrient data, collected by the City of Columbus, were also analyzed for trends in concentration during periods of expected stratification. Based on the results of the two campaigns, when compared to withdrawing water through the middle gate, withdrawing water through the lower gate seemed to increase shear-driven mixing across the thermocline, which resulted in an increase in the depth of the epilimnion throughout the lower part of Hoover Reservoir. The observations from this study, if repeatable and driven primarily by changes in gate operations, can inform nutrient management strategies for Hoover Reservoir. Increased mixing across the thermocline may potentially supply nutrients from the hypolimnion to algae in the epilimnion. Although operation of the lower gate has the potential to export nutrients from the hypolimnion (where the concentrations of nutrients have typically been higher during summer months) through two mechanisms (direct withdrawal and mixing into the epilimnion), supply of nutrients to the epilimnion through enhanced mixing could lead to a short-term increase in algal populations. Therefore, further study is recommended to (1) test the repeatability of the results of gate changes on water-quality distributions and circulation patterns in lower Hoover Reservoir, (2) identify the immediate effect of gate changes on nutrient concentrations in the water column, and (3) identify the best management practices to reduce the nutrient storage in the hypolimnion of Hoover Reservoir without increasing the potential for nutrient transport to the highly productive epilimnion.

Ohio↗