Scott J Ikard
I am a licensed Professional Engineer with thirteen years of professional research and project engineering experience in geophysics, hydrogeology, and hydrology, with auxiliary experiences in fluvial geomorphology, civil, and geotechnical engineering.
Currently, I am a Hydrologist in the Geophysics unit of the United States Geological Survey's Texas Water Science Center, in Austin, Texas. I plan and perform applied research studies and projects that broadly encompass proposals development, geophysical and hydrologic survey planning, instrumentation, data acquisition, data processing, and publication of surface, waterborne, airborne, and borehole hydrogeophysical data. The goals of my applied work frequently include delineation and correlation of aquifer systems, geophysical assessments of local and regional surface and ground water exchange-flow patterns, quantification and uncertainty analysis of hydraulic and geophysical properties of the vadose zone, confined and unconfined aquifers throughout the world.
United States Geological Survey. GS1315-11 Hydrologist/Geophysicist. Austin, Texas 06/2014 – Present
- Oversight, site selection, planning and preparation, and coordination of groundwater conservation districts, river authorities, municipal and government agencies, and public stakeholders in research-drilling and near-surface hydrogeophysical projects.
- Planning, implementation, and oversight of waterborne and land-based geophysical field surveys using time and frequency domain electromagnetics, self-potential mapping, electric resistance tomography, seismic refraction, dilution gaging, water-level monitoring, differential global positioning systems, Calibrated surface and borehole geophysical and hydrologic instruments, and performed troubleshooting of logging instruments and data acquisition systems in the field.
- Performed field acquisition, pre-processing, inversion, and post-processing of vertical electrical soundings and transient electromagnetic soundings, as well as surface self-potential and electrical resistivity tomography data, to map alluvial and deep confined aquifers and produce conceptual hydro-stratigraphic models for groundwater flow modeling.
- Developed data-processing codes and algorithms for (a) automated hydro-stratigraphic interpretation and geo-electric correlations from geophysical well logs and drillers logs, (b) automated baseflow separation and recession analysis, (c) digital signal processing, (d) groundwater flow modeling, particle tracking, parameter estimation and uncertainty analysis, (e) 2D and 3D forward and inverse modeling of self-potential and DC resistivity data using finite elements, finite differences, and linear filter theory.
- Published innovative, novel research in peer-reviewed journals and USGS reports.
Science and Products
Filter Total Items: 18
Time-Domain Electromagnetic Data Used in the Assessment of the Freshwater/Saline-Water Transition Zone within the Hueco Bolson, Fort Bliss Area, El Paso, Texas 2017-2019
Declining groundwater levels in the Hueco Bolson have raised concerns about the amount of available groundwater and the potential for water-quality changes. Fresh groundwater stored in the aquifer is bordered by regions of brackish-to-saline groundwater, and as the water levels in the Hueco Bolson have declined the local and regional hydraulic gradients have been altered such that the...
Investigation of Scale-dependent Groundwater/Surface-water Exchange in Rivers by Gradient Self-Potential Logging: Numerical Model and Field Experiment Data, Quashnet River, Massachusetts, October 2017 (ver. 2.0, November 2020)
This data release contains waterborne self-potential (SP) logging data measured during 48 laboratory experiments and three field experiments that were performed to develop an efficient, accurate method for detecting (in the laboratory) and geolocating (in the field) focused vertical groundwater discharge (surface-water gains) and recharge (surface-water losses) in a river. The...
Geoelectric and Seismic Data acquired in the Precambrian Granite Gravel Aquifer, Llano Uplift, Central Texas, May 2017 - August 2018
This data release contains geophysical data and well and borehole driller's logs acquired at a small field site in the Llano Uplift of central Texas. The field site is underlain by the unconfined Precambrian Granite Gravel aquifer and the Precambrian Town Mountain Granite bedrock from which the Granite Gravel Aquifer was derived through chemical and mechanical weathering. The data set...
650-m Profiles of Self-Potential, Contact Resistance, and Electric Resistance Tomography Measurements Adjacent to Hamilton Creek, Burnet County, Texas, July 2017 - January 2018
This data release consists of three different types of geoelectric data measured along three curvilinear profiles during two separate geophysical surveys completed on July 9, 2017 and January 9, 2018. The datasets include three self-potential (SP) profiles, two spatially-coincident electric contact-resistance (CR) profiles, and two spatially-coincident electric resistance tomography (ERT...
Data Used to Assess the Hydrogeologic Framework with Emphasis on the Ogallala and Edwards-Trinity Aquifers, in and Near Gaines, Terry, and Yoakum Counties, Texas, 2018
More than 11,500 well records, such as geophysical logs, drilling descriptions, and published hydrogeologic framework information, were evaluated to help characterize the framework of hydrogeologic units in and near Gaines, Terry, and Yoakum Counties, Texas. Additional geophysical data were collected to improve the spatial coverage across the study area and to reduce uncertainty with...
14.86 km Profiles of the Electric and Self-potential Fields Measured in the Lower Guadalupe River Channel, Texas Interior Gulf Coastal Plain, September 2016
This data release consists of three geophysical data sets measured in the lower Guadalupe River channel, south-central Texas, and one supplementary geophysical data set measured in a laboratory. The lower Guadalupe River is incised into the outcrop of the Carrizo-Wilcox aquifer in south-central Texas. The river and the aquifer are hydraulically connected across the outcrop, although the...
Filter Total Items: 19
New insights into surface-water/groundwater exchanges in the Guadalupe River, Texas, from floating geophysical methods
In south-central Texas, the amount of streamflow in the Guadalupe River is a primary concern for local and downstream communities because of municipal, agricultural, wildlife, and recreational uses. Understanding the flow paths and rates of exchange between the surface water in the river and the groundwater in the underlying Carrizo-Wilcox aquifer is vital for understanding the water...
Authors
Scott Ikard, John R. Banta, Gregory P. Stanton
New insights on scale-dependent surface-groundwater exchange from a floating self-potential Dipole
In south-central Texas the lower Guadalupe River has incised into the outcrop of the Carrizo-Wilcox aquifer. The river and the aquifer are hydraulically connected across the outcrop, although the connectivity is obscured at the surface by alluvium and surface-water and groundwater exchange dynamics are currently poorly understood. To investigate surface-water and groundwater exchange...
Authors
Scott Ikard, Andrew Teeple, Jason D. Payne, Gregory P. Stanton, John R. Banta
Hydrogeophysical investigations of earthen dams – Two California case studies
Excessive groundwater seepage can be a common engineering concern with earthen dams. The application of geophysical methods, whether for characterization or for long-term monitoring, to help inform mitigation strategies is becoming a more common addition to these investigations. The U.S. Geological Survey (USGS) has completed geophysical investigations at several earthen dams in...
Authors
Bethany L. Burton, Paul A. Bedrosian, Burke J. Minsley, Scott Ikard, Michael H. Powers
Improving our understanding of hydraulic-electrical relations: A case study of the surficial aquifer in Emirate Abu Dhabi
Transmissivity is a bulk hydraulic property that can be correlated with bulk electrical properties of an aquifer. In aquifers that are electrically-resistive relative to adjacent layers in a horizontally stratified sequence, transmissivity has been shown to correlate with bulk transverse resistance. Conversely, in aquifers that are electrically-conductive relative to adjacent layers...
Authors
Scott Ikard, Wade H. Kress
Hydrogeophysical investigations at Hidden Dam, Raymond, California
Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam...
Authors
Burke J. Minsley, Bethany L. Burton, Scott Ikard, Michael H. Powers
Geophysical investigations at Hidden Dam, Raymond, California: Summary of fieldwork and data analysis
Geophysical field investigations have been carried out at the Hidden Dam in Raymond, California for the purpose of better understanding the hydrogeology and seepage-related conditions at the site. Known seepage areas on the northwest right abutment area of the downstream side of the dam are documented by Cedergren. Subsequent to the 1980 seepage study, a drainage blanket with a subdrain...
Authors
Burke J. Minsley, Bethany L. Burton, Scott Ikard, Michael H. Powers
Non-USGS Publications**
Ikard, S. J., A. Revil, A. Jardani, W. F. Woodruff, M. Parekh, and M. Mooney (2012), Saline pulse test monitoring with the self-potential method to nonintrusively determine the velocity of the pore water in leaking areas of earth dams and embankments, Water Resour. Res., 48, W04201, doi:10.1029/2010WR010247.
Ikard, S. J., Gooseff, M. N., Barrett, J. E. and Takacs‐Vesbach, C. (2009), Thermal characterisation of active layer across a soil moisture gradient in the McMurdo Dry Valleys, Antarctica. Permafrost Periglac. Process., 20: 27-39. doi:10.1002/ppp.634
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 18
Time-Domain Electromagnetic Data Used in the Assessment of the Freshwater/Saline-Water Transition Zone within the Hueco Bolson, Fort Bliss Area, El Paso, Texas 2017-2019
Declining groundwater levels in the Hueco Bolson have raised concerns about the amount of available groundwater and the potential for water-quality changes. Fresh groundwater stored in the aquifer is bordered by regions of brackish-to-saline groundwater, and as the water levels in the Hueco Bolson have declined the local and regional hydraulic gradients have been altered such that the...
Investigation of Scale-dependent Groundwater/Surface-water Exchange in Rivers by Gradient Self-Potential Logging: Numerical Model and Field Experiment Data, Quashnet River, Massachusetts, October 2017 (ver. 2.0, November 2020)
This data release contains waterborne self-potential (SP) logging data measured during 48 laboratory experiments and three field experiments that were performed to develop an efficient, accurate method for detecting (in the laboratory) and geolocating (in the field) focused vertical groundwater discharge (surface-water gains) and recharge (surface-water losses) in a river. The...
Geoelectric and Seismic Data acquired in the Precambrian Granite Gravel Aquifer, Llano Uplift, Central Texas, May 2017 - August 2018
This data release contains geophysical data and well and borehole driller's logs acquired at a small field site in the Llano Uplift of central Texas. The field site is underlain by the unconfined Precambrian Granite Gravel aquifer and the Precambrian Town Mountain Granite bedrock from which the Granite Gravel Aquifer was derived through chemical and mechanical weathering. The data set...
650-m Profiles of Self-Potential, Contact Resistance, and Electric Resistance Tomography Measurements Adjacent to Hamilton Creek, Burnet County, Texas, July 2017 - January 2018
This data release consists of three different types of geoelectric data measured along three curvilinear profiles during two separate geophysical surveys completed on July 9, 2017 and January 9, 2018. The datasets include three self-potential (SP) profiles, two spatially-coincident electric contact-resistance (CR) profiles, and two spatially-coincident electric resistance tomography (ERT...
Data Used to Assess the Hydrogeologic Framework with Emphasis on the Ogallala and Edwards-Trinity Aquifers, in and Near Gaines, Terry, and Yoakum Counties, Texas, 2018
More than 11,500 well records, such as geophysical logs, drilling descriptions, and published hydrogeologic framework information, were evaluated to help characterize the framework of hydrogeologic units in and near Gaines, Terry, and Yoakum Counties, Texas. Additional geophysical data were collected to improve the spatial coverage across the study area and to reduce uncertainty with...
14.86 km Profiles of the Electric and Self-potential Fields Measured in the Lower Guadalupe River Channel, Texas Interior Gulf Coastal Plain, September 2016
This data release consists of three geophysical data sets measured in the lower Guadalupe River channel, south-central Texas, and one supplementary geophysical data set measured in a laboratory. The lower Guadalupe River is incised into the outcrop of the Carrizo-Wilcox aquifer in south-central Texas. The river and the aquifer are hydraulically connected across the outcrop, although the...
Filter Total Items: 19
New insights into surface-water/groundwater exchanges in the Guadalupe River, Texas, from floating geophysical methods
In south-central Texas, the amount of streamflow in the Guadalupe River is a primary concern for local and downstream communities because of municipal, agricultural, wildlife, and recreational uses. Understanding the flow paths and rates of exchange between the surface water in the river and the groundwater in the underlying Carrizo-Wilcox aquifer is vital for understanding the water...
Authors
Scott Ikard, John R. Banta, Gregory P. Stanton
New insights on scale-dependent surface-groundwater exchange from a floating self-potential Dipole
In south-central Texas the lower Guadalupe River has incised into the outcrop of the Carrizo-Wilcox aquifer. The river and the aquifer are hydraulically connected across the outcrop, although the connectivity is obscured at the surface by alluvium and surface-water and groundwater exchange dynamics are currently poorly understood. To investigate surface-water and groundwater exchange...
Authors
Scott Ikard, Andrew Teeple, Jason D. Payne, Gregory P. Stanton, John R. Banta
Hydrogeophysical investigations of earthen dams – Two California case studies
Excessive groundwater seepage can be a common engineering concern with earthen dams. The application of geophysical methods, whether for characterization or for long-term monitoring, to help inform mitigation strategies is becoming a more common addition to these investigations. The U.S. Geological Survey (USGS) has completed geophysical investigations at several earthen dams in...
Authors
Bethany L. Burton, Paul A. Bedrosian, Burke J. Minsley, Scott Ikard, Michael H. Powers
Improving our understanding of hydraulic-electrical relations: A case study of the surficial aquifer in Emirate Abu Dhabi
Transmissivity is a bulk hydraulic property that can be correlated with bulk electrical properties of an aquifer. In aquifers that are electrically-resistive relative to adjacent layers in a horizontally stratified sequence, transmissivity has been shown to correlate with bulk transverse resistance. Conversely, in aquifers that are electrically-conductive relative to adjacent layers...
Authors
Scott Ikard, Wade H. Kress
Hydrogeophysical investigations at Hidden Dam, Raymond, California
Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam...
Authors
Burke J. Minsley, Bethany L. Burton, Scott Ikard, Michael H. Powers
Geophysical investigations at Hidden Dam, Raymond, California: Summary of fieldwork and data analysis
Geophysical field investigations have been carried out at the Hidden Dam in Raymond, California for the purpose of better understanding the hydrogeology and seepage-related conditions at the site. Known seepage areas on the northwest right abutment area of the downstream side of the dam are documented by Cedergren. Subsequent to the 1980 seepage study, a drainage blanket with a subdrain...
Authors
Burke J. Minsley, Bethany L. Burton, Scott Ikard, Michael H. Powers
Non-USGS Publications**
Ikard, S. J., A. Revil, A. Jardani, W. F. Woodruff, M. Parekh, and M. Mooney (2012), Saline pulse test monitoring with the self-potential method to nonintrusively determine the velocity of the pore water in leaking areas of earth dams and embankments, Water Resour. Res., 48, W04201, doi:10.1029/2010WR010247.
Ikard, S. J., Gooseff, M. N., Barrett, J. E. and Takacs‐Vesbach, C. (2009), Thermal characterisation of active layer across a soil moisture gradient in the McMurdo Dry Valleys, Antarctica. Permafrost Periglac. Process., 20: 27-39. doi:10.1002/ppp.634
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.