Geology topics

Jerad Bales

Publications and source records attributed to Jerad Bales.

8 recordsLinked to original sources

USGS2018

What goes up must come down: Integrating air and water quality monitoring for nutrients

Excess nitrogen and phosphorus (“nutrients”) loadings continue to affect ecosystem function and human health across the U.S. Our ability to connect atmospheric inputs of nutrients to aquatic end points remains limited due to uncoupled air and water quality monitoring. Where connections exist, the information provides insights about source apportionment, trends, risk to sensitive ecosystems, and efficacy of pollution reduction efforts. We examine several issues driving the need for better integrated monitoring, including: coastal eutrophication, urban hotspots of deposition, a shift from oxidized to reduced nitrogen deposition, and the disappearance of pristine lakes. Successful coordination requires consistent data reporting; collocating deposition and water quality monitoring; improving phosphorus deposition measurements; and filling coverage gaps in urban corridors, agricultural areas, undeveloped watersheds, and coastal zones.

Environmental Science and Technology↗

USGS2014

Improving groundwater predictions utilizing seasonal precipitation forecasts from general circulation models forced with sea surface temperature forecasts

Recent studies have found a significant association between climatic variability and basin hydroclimatology, particularly groundwater levels, over the southeast United States. The research reported in this paper evaluates the potential in developing 6-month-ahead groundwater-level forecasts based on the precipitation forecasts from ECHAM 4.5 General Circulation Model Forced with Sea Surface Temperature forecasts. Ten groundwater wells and nine streamgauges from the USGS Groundwater Climate Response Network and Hydro-Climatic Data Network were selected to represent groundwater and surface water flows, respectively, having minimal anthropogenic influences within the Flint River Basin in Georgia, United States. The writers employ two low-dimensional models [principle component regression (PCR) and canonical correlation analysis (CCA)] for predicting groundwater and streamflow at both seasonal and monthly timescales. Three modeling schemes are considered at the beginning of January to predict winter (January, February, and March) and spring (April, May, and June) streamflow and groundwater for the selected sites within the Flint River Basin. The first scheme (model 1) is a null model and is developed using PCR for every streamflow and groundwater site using previous 3-month observations (October, November, and December) available at that particular site as predictors. Modeling schemes 2 and 3 are developed using PCR and CCA, respectively, to evaluate the role of precipitation forecasts in improving monthly and seasonal groundwater predictions. Modeling scheme 3, which employs a CCA approach, is developed for each site by considering observed groundwater levels from nearby sites as predictands. The performance of these three schemes is evaluated using two metrics (correlation coefficient and relative RMS error) by developing groundwater-level forecasts based on leave-five-out cross-validation. Results from the research reported in this paper show that using precipitation forecasts in climate models improves the ability to predict the interannual variability of winter and spring streamflow and groundwater levels over the basin. However, significant conditional bias exists in all the three modeling schemes, which indicates the need to consider improved modeling schemes as well as the availability of longer time-series of observed hydroclimatic information over the basin.

Georgia↗

USGS1997

Review of selected features of the natural system model, and suggestions for applications in south Florida

A study was conducted to review selected features of the Natural System Model, version 4.3. The Natural System Model is a regional-scale model that uses recent climatic data and estimates of historic vegetation and topography to simulate pre-canal-drainage hydrologic response in south Florida. Equations used to represent the hydrologic system and the numerical solution of these equations in the model were documented and reviewed. Convergence testing was performed using 1965 input data, and selected other aspects of the model were evaluated. Some conclusions from the evaluation of the Natural System Model include the following observations. Simulations were generally insensitive to the temporal resolution used in the model. However, reduction of the computational cell size from 2-mile by 2-mile to 2/3-mile by 2/3-mile resulted in a decrease in spatial mean ponding depths for October of 0.35 foot for a 3-hour time step. Review of the computer code indicated that there is no limit on the amount of water that can be transferred from the river system to the overland flow system, on the amount of seepage from the river to the ground-water system, on evaporation from the river system, or on evapotranspiration from the overland-flow system. Oscillations of 0.2 foot or less in simulated river stage were identified and attributed to a volume limiting function which is applied in solution of the overland-flow equations. The computation of the resistance coefficient is not consistent with the computation of overland-flow velocity. Ground-water boundary conditions do not always ensure a no-flow condition at the boundary. These inconsistencies had varying degrees of effects on model simulations, and it is likely that simulations longer than 1 year are needed to fully identify effects. However, inconsistencies in model formulations should not be ignored, even if the effects of such errors on model results appear to be small or have not been clearly defined. The Natural System Model can be a very useful tool for estimating pre-drainage hydrologic response in south Florida. The model includes all of the important physical processes needed to simulate a water balance. With a few exceptions, these hydrologic processes are represented in a reasonable manner using empirical, semiempirical, and mechanistic relations. The data sets that have been assembled to represent physical features, and hydrologic and meteorological conditions are quite extensive in their scope. Some suggestions for model application were made. Simulation results from the Natural System Model need to be interpreted on a regional basis, rather than cell by cell. The available evidence suggests that simulated water levels should be interpreted with about a plus or minus 1 foot uncertainty. It is probably not appropriate to use the Natural System Model to estimate pre-drainage discharges (as opposed to hydroperiods and water levels) at a particular location or across a set of adjacent computational cells. All simulated results for computational cells within about 10 miles of the model boundaries have a higher degree of uncertainty than results for the interior of the model domain. It is most appropriate to interpret the Natural System Model simulation results in connection with other available information. Stronger linkages between hydrologic inputs to the Everglades and the ecological response of the system would enhance restoration efforts.

Florida↗

USGS1995

Simulation of hydrodynamics and solute transport in the Pamlico River estuary, North Carolina

An investigation was conducted to characterize flow, circulation, and solute transport in the Pamlico River estuary, North Carolina. The study included a detailed field-measurement program and the calibration, validation, and application of a physically realistic numerical model of hydro- dynamics and transport. Water level, salinity, water temperature, wind speed and direction, and current data were collected during March 1988 through September 1992, and were used to characterize physical conditions in the estuary. Data from pre- existing streamflow gaging stations and meteoro- logical stations were also used. A two-dimensional vertically averaged hydrodynamic and solute transport model was applied to the 48-kilometer study reach. The model domain was discretized into 5,620 separate 200- by 200-meter computational cells. Model calibration was achieved through adjustment of parameters for June 14-30, 1991. Data from selected periods in 1989 and 1991 were used for model validation. Water levels used for model calibration and validation ranged from -0.052 to 0.698 meter; salinities ranged from 0.1 to 13.1 parts per thousand; and wind speeds ranged from calm to 22 meters per second. The model was tested for stratified and unstratified conditions. Simulated and observed data were used to evaluate model performance. The calibrated model was applied for selected periods in 1989 and 1991. Instantaneous flows were simulated at each boundary and at mid- estuary. Circulation patterns were characterized using vector plots, particle tracking, and solute transport. Particle tracks showed that materials released at mid-estuary may remain in the system for 25 days or longer.

North Carolina↗

USGS1995

Simulation of hydrodynamics and solute transport in the Neuse River estuary

An investigation was conducted to characterize flow, circulation, and transport in the Neuse River estuary, North Carolina. The study included a detailed field-measurement program and the calibration, validation, and application of a physically realistic numerical model of hydro- dynamics and transport through a 40-kilometer reach of the estuary. Water level, salinity, water temperature, wind speed and direction, current velocity, and bathymetric data were collected during March 1988 through September 1992. Additional data from pre-existing continuous-record streamflow gaging stations and meteorological stations also were used. A two-dimensional, vertically averaged hydrodynamic and solute transport model was applied to the study reach. The model domain was discretized into 200- by 200-meter computational cells. Model calibration was achieved through adjustment of model parameters for the period June 1-24, 1991. Additional simulations for periods in 1989 and 1991 were run to validate the model. The model was calibrated and validated for water levels ranging from -0.104 to 0.908 meters, salinities ranging from 2.8 to 22.0 parts per thousand, and wind speed from calm to 9 meters per second. The model was tested for stratified and unstratified conditions. Simulated and observed level, salinity, and velocity data were used to evaluate the model. The calibrated model was applied to simulate flows, circulation, and salinity distributions for four simulation periods in 1989 and 1991. Comparisons of simulated results for a period in June 1991 were made between the Neuse and Pamlico models to characterize differences between the two systems.

Open-File Report↗

USGS1994

Flow and salinity in West Neck Creek, Virginia, 1989-92, and salinity in North Landing River, North Carolina, 1991-92

Flow and salinity were monitored during 1989-92 in West Neck Creek, Virginia, which provides a direct hydraulic connection between the brackish waters of Chesapeake Bay and the relatively fresh waters of Currituck Sound. During the 308 days for which data were available, flow was to the south 64 percent of the time, but 80 percent of the southward flows were less than 40 cubic feet per second. Flows ranged from 356 cubic feet per second to the south to 50 cubic feet per second to the north, and the highest flows were associated with precipitation events. Salinity ranged from less than 0.1 to 24.5 parts per thousand, and the highest salinities were observed during periods of sustained, high northerly winds. Salt transport ranged from 34,510 tons per day to the south to 302 tons per day to the north.

North Carolina, Virginia↗

USGS1992

Two-dimensional circulation modeling of the Pamlico River estuary, North Carolina

A two dimensional, vertically averaged, unsteady flow model was applied to a 50- kilometer reach of the Pamlico River estuary, North Carolina. The model computational grid, which consists of about 16,000 square cells, each 200 meters on a side, was developed from more than one million depth soundings. Information from a comprehensive data-collection network, including six water-level stations, six temperature and salinity measurement stations, and one wind measurement station, was used to provide data for boundary conditions and for model calibration. Preliminary model results for this ongoing study were sensitive to the presence of a lateral water-level gradient at the downstream boundary. For the simulation period, water-level oscillations at the downstream boundary were much more important in controlling Pamlico River flows than were local winds blowing over the surface of the estuary. Average absolute differences between observed and simulated water levels at two measurement sites were less than 2 centimeters for the 8-day calibration period.

North Carolina↗

USGS1991

Water-quality data from continuously monitored sites in the Pamlico and Neuse River estuaries, North Carolina, 1989-90

Beginning in April 1989, water quality measurements were made at six sites in or near Pamlico River estuary and at five sites in or near the Neuse River estuary. Measurements taken at 15-minute intervals included near-surface and near-bottom specific conductance; near-surface water temperature; and near-surface, mid-depth, and near-bottom dissolved-oxygen concentrations. Water-quality data obtained from continuously-monitored sites in the Pamlico River estuary and the Neuse River estuary are presented for the period April 1989 through September 1990. Instantaneous values for selected periods are summarized in a series of box plots. Instantaneous maximum and minimum values are also tabulated. Daily mean values of salinity, water temperature, and dissolved-oxygen concentrations for the entire period are presented in tables and graphs.

North Carolina↗