WATERSHED SCALE CHARACTERIZATION OF GLACIAL AND BEDROCKAQUIFERS IN EASTERN NEBRASKA

Jared D. Abraham, MSc., Senior Research Geophysicist, XRI

James C. Cannia, P.G., Senior Geologist, XRI

Kathleen Cameron, P.G. Eastern Nebraska Water Resources Assessment (ENWRA) Project Coordinator 

Theodore H. Asch, PhD, P.Gp., Research Geophysicist, XRI

Lawrence, KSMay 21, 2015

COAUTHORS• Clint Carney, MSc., P.G. – Geologist

• Andrew Genco, MSc. – Geophysicist

• Rachel Woolf, MSc. – Geophysicist

• Todd Meglich, BSc. – Geophysicist

• Kristen Pierce, BSc. –Geophysicist

• Trevor Irons, PhD. - Research Geophysicist

• Greg Steele, MSc., P.G., Senior Hydrologist

6 Eastern Nebraska Natural Resources Districts (NRD)

Formed in 2006 to assess the glaciated area

Agency partners: US Geological Survey (USGS), University of Nebraska Lincoln Conservation Survey Division (CSD), Nebraska Department of Natural Resources (NDNR), and Nebraska Department of Environmental Quality (NDEQ)

3 pilot study sites to test toolsets First use of helicopter mapping in 2007 Application of the flight technology

evolved over time

Groundwater resources are more limited in eastern Nebraska Much of the groundwater supply in eastern Nebraska is from aquifers that are within & below glacial deposits They can be laterally discontinuous, have highly variable geometry, and are heterogeneous making them very complex to map Delineation of these aquifers is critical for management purposes

The quantity of water may be limited due to the spatially confined nature of the aquifers Natural water quality varies in different aquifers and human induced (example nitrates) may infiltrate to these aquifers and degrade their quality

CROSS SECTION ACROSS NEBRASKA

The Groundwater Atlas of Nebraska Resource Atlas No. 4b/2013 Third (revised) Edition Conservation and Survey Division School of Natural Resources Institute of Agriculture and Natural Resources University of Nebraska - Lincoln

AEM survey

AEM data processing incorporates existing data along flight lines Test holes logged by state geologists since 1940 Deep oil and gas well cores Study sites – local studies and geologic reports Registered well logs

RECON FLIGHTS

LegendENWRA Oct 2014 Flight Lines

LENRD Grid Fall 2014

Planned Spring 2015 Flights

Rivers

Existing ENWRA Pilot and Partner Studies

ENWRA NRDs

Lewis & Clark

Lower Elkhorn

Lower Platte North

Lower Platte South

Nemaha

Papio-Missouri River

E. AUKEN, U. OF AARHUS, DENMARK

FLIGHT LINE PLANNING• Lines Planned along CSD Cross Sections

• Pipeline data were acquired from Platts(www.platts.com) CSD/ENWRA assisted in acquiring data on public power

systems Auburn Board of Public Works, Burt County Power District, Butler County Power District,

Cedar-Knox Power District, City of Fremont, Cornhusker Public Power District, Cuming County Power District, Elkhorn Rural Public Power District, Lincoln Electric Systems, Loup Power District, Nebraska Public Power District, Nemaha-Marshall Electric Cooperative, Norris Public Power District, North Central Public Power District, Northeast Nebraska Public Power District, Omaha Public Power District, Polk County Rural Public Power District, Seward County Public Power District, Stanton County Public Power District

• Flight lines were adjusted to optimize data collection

October 11-19th, 2014 7 days of data collection 1 weather day (wind Oct 17)

April 16-21th, 2015 4 days of data collection 2 weather day (rain April 18-19)

2,368 + 1,430 line-km

50 km1,100 line-km

50 km

AEM EASTERN NEBRASKA 2014

2,532 line-km

IN FIELD QA/QC AND INVERSION• Within 24 hours we invert

• SkyTEM 508 system-first time gate 12 μsec 3.0 μsecwide and last time gate of 10.0 msec

• Aarhus Workbench SCI was used with 30 layer smooth inversion. First layer 5 m.

BACKGROUND BOREHOLE DATA

CSD HISTORICAL CROSS SECTIONS

CSD CROSS SECTIONS

RESISTIVITY VERSUS LITHOLOGY AND AQUIFER MATERIALS

• 39 CSD boreholes with lithology and resistivity geophysical logs

• ~209,000 individual measurementsN

on A

quife

r

Mar

gina

l Aqu

ifer

Prin

cipa

l Aqu

ifer

Coa

rse

Aqu

ifer

LITHOLOGY VERSUS AQUIFER MATERIALNon Aquifer Marginal Aquifer

LITHOLOGY VERSUS AQUIFER MATERIALCoarse Aquifer 21 to 50 Ohm-mPrincipal Aquifer

CSD 5‐GT‐80 300 METERS OFF LINE

EXAMPLE CROSS SECTION

20 km300 m

STRUCTURE IN THE PALEOZOIC

400 m

15 km

WATER QUALITY CHANGES

3D VIEW OF THE RESITIVITY OF ENWRA

20 km300 m

AEM VERSUS CSD CROSS SECTION

111 km (69 mile) cross section with 27 test holes totaling 2,057 m(Average depth of 76 m(250 ft)) $160,000AEM cost (Average depth 304 m (1,000 ft)) $44,46428% of the cost of drilling

3D OF THE 2014 AEM IN LENRDNorth

3D OF THE 2014 AEM IN LENRDNorth

3D OF THE 2014 AEM IN LENRD

North

3D OF THE 2014 AEM IN LENRD

North

3D OF THE 2014 AEM IN LENRD

North

GOOGLE EARTH FILES

SURVEY CONCLUSIONS• Aquifer resources vary considerably within the Quaternary and Tertiary system.

• The aquifer material is thicker in the western part of the ENWRA.

• The Quaternary and Tertiary material act as the principal aquifer in the west.

• Non-aquifer (aquitard) materials are abundant in the central and eastern portions of the survey area, with till and loess sequences exceeding 60 m.

• The full sequence of Cretaceous strata present in eastern Nebraska was detected by the AEM system.

• The full thickness of the Dakota (Kd) is revealed in the AEM survey. The AEM indicated potential areas of development.

• The structure in the Paleozoic was mappable in southeastern NE

• The line spacing at 3 miles grids can be used to delineate groundwater management areas.

• The reconnaissance line spacing for the ENWRA flights shows areas of interest for future work.

ACKNOWLEDGMENTS

• Susan Olafsen Lackey- Nebraska Conservation Survey Division (CSD), University of Nebraska Lincoln, School of Natural Sciences

• Rick Wozniak and Curt Becker – Lower Elkhorn Natural Resources District (LENRD)

• Alan Stack, Pilot –Native American Helicopters

• Jason Marcil, SkyTEM, Project Manager– Devbrio Géophysique Inc.

• B.J. Crocker, Owner - Native American Helicopters

• Flemming Effersø, CEO – SkyTEM

• Bill Brown, North American Sales – SkyTEM

• Andrea Viezzoli, Aarhus Geophysics

CONTACTS

Jared D. Abraham, MSc.Senior Research GeophysicistGolden, CO (303)-263-8318Jared.Abraham@xrigeo.com

Kathleen Cameron, P.G.ENWRA Project CoordinatorLincoln, NEkcameron_enwra@lpsnrd.org(402)-476-2729

www.xrigeo.com

www.enwra.org