investigations of playa basins as point source...
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Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
INVESTIGATIONS OF PLAYA BASINS AS POINT SOURCE RECHARGE TO THE HIGH
PLAINS AQUIFER
Randy L. STOTLER1, Kait SALLEY1, William C. JOHNSON2, Dakota J. BURT2, and Mark W. BOWEN3
1 Department of Geology, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66045
2 Department of Geography and Atmospheric Science, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66045
3 Geography and Urban Planning, University of Wisconsin Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Introduction
• High Plains (Ogallala) aquifer and Playas
• Types of recharge
– Diffuse
– Focused
• Timing of recharge
– Environmental tracers
– Agricultural contaminants
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Buried playa (Kearny County)
“buffalo wallow” (Haskell County)
>22,000 playas in Kansas
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
4
From USGS Circular 1333
Note: Sandhills lakes not included in this assessment
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Portals to the High Plains Aquifer?
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Goal of this phase of playa research is one of determining if playas indeed serve as point sources for recharge of the High Plains Aquifer (in Kansas)
Approaches Vadose zone geochemistry and other proxies of water flux Groundwater modeling Surface water balance analyses Related issues, e.g., accelerated sedimentation of playa basins
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Ehmke Playa
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Temporal and Spatial Changes
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playa instrumentation
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Tower array (recording every 10 minutes)
Wind velocity and direction Temperature and humidity Solar radiation (pyranometer) Rain Radiation (net) Surface water level (acoustic) Still and video imagery
Sub-surface sensors (upper 3 m)
Soil heat flux (thermocouples and heat flux plates) Temperature, EC, water content Water potential sensors
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Instrumented pit profile characterization
0
50
100
150
200
250
0 50 100
L*
0 1 2 3
a*
0 5 10 15
b*
AMS 14C ages (cal yrs BP)
3320 ± 30
3835 ± 30
4145 ± 30
5300 ± 30
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Dust collection
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Drone-based monitoring
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
What about accelerated sedimentation?
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Vegetation Buffers
Courtesy of Dave Haukos KSU
Sedimentation and playa function?
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
210Pb sediment dating half life = 22.2 years atmospheric deposition
Full-core analyses: Color imagery Geochemistry (XRF) Magnetic susceptibility Gray-scale imagery L*a*b* and Munsell colors Micromorphology Particle size distribution Stable isotopes
Crack filling?
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Chemical tracers: Chloride Bromide Nitrate Isotope analyses: δ2H and δ18O, 3H
(wet and dry atmospheric fallout)
(precipitation and plant-soil interactions)
Vadose Zone Geochemistry
(groundwater source and age)
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Vadose Zone
Core is sealed in the field, and returned to the lab for fluid extraction
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Sample Preparation
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
PROJECT STATUS
1. Instrument station active
2. Waiting for sufficient rainfall to inundate playa
3. Hydraulic conductivity studies and infiltration tests
4. Continuous coring of the vadose zone underway
• Chemostratigraphy (tracers - Cl, Nitrates; isotopes – 13C, 15N, 18O, 3H) • Lithostratigraphy (physical and chemical characterization) • Magnetostratigraphy (susceptibility, IRM) • Pedostratigraphy (modern and buried soils)
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Regional Results
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Vadose Zone Chemistry
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Nitrate concentration (μg-N/g)
Tritium concentration (TU)
McMahon et al., 2006
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017 23
GMD #3
GMD #4
GMD #5
GMD #1
GMD #2
Rangeland vadose zone; recharge = 5 mm/yr Irrigated farmland vadose zone; recharge = 40-50 mm/yr Irrigated farmland vadose zone; recharge = 100 mm/yr
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Regional Study
• Environmental tracers – Stable isotopes: climate
– Tritium (3H), CFCs: recharge since 1950
– Radiocarbon (14C): recharge 500 – 35,000 years ago
• Agricultural contaminants – Recharge since 1950s
• Nitrate
• Pesticides
• Fertilizers
• New data and literature review
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Tritium and CFCs in HPA groundwater
Red = detect
Blue = non-detect
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Playa Recharge Pathways
25
From PLJV
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017 26
From USGS Circular 1333
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017 27
From USGS Circular 1333
Chemical Transit
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Summary
• Playas provide: – Important recharge pathways to HPA
– Chemical transit rates increase
• Sedimentation issues
• Results vary playa to playa – (size, geology, climate, etc.)
• Work on-going to upscale results from individual playas to regional HPA
Playas and High Plains Recharge; [email protected] Rainwater Basin Joint Venture 2017
Thank You . . .
Funding and other support: EPA, KU, KGS, UW-Oshkosh, Conoco-Phillips, PLJV, US Fish & Wildlife, NRCS, KWO