69th SWCS International Annual Conference “Making Waves in Conservation: Our Life on Land and Its Impact on Water” July 27-30, 2014 Lombard, IL

1. 8/12/2014
1
A Novel Test of Artificial Recharge in
the Mississippi River Alluvial
Aquifer in Arkansas
Michele L. Reba, PhD, PE
USDA-ARS
Delta Water Management Research Unit
USDA
Preserving water quality & availability for agriculture
in the Mississippi River Basin
Delta Water Management Research
Unit
• Jonesboro, AR
• Arkansas State University
• 2011-Watershed Physical
Processes Unit
• 2014-stand alone unit
Arkansas
4.5 million
Nebraska
8.4 million
California
7.3 million
Texas
5.4 million
Water Quantity
Arkansas
6.1 M acres farmed
4.5 M acres irrigated
Alluvial Aquifer
• 2008 (Mgal/d)
– Pumped: 7,022
– Sustainable Yield: 2,987
– Unmet Demand: 4,035
• Agriculture 96%
Source: Arkansas Natural Resources Commission 2011
Approaches Toward
Sustainability
• Conservation
• Surface-water diversions
• Technology
• On-farm storage
• Artificial recharge
Potential Storage in Alluvial Aquifer
• Water removed from storage since pumping
began: 1.5 trillion cubic ft (or 35 million acre ft)
• Equivalent water depth if applied over area of
aquifer: 4 ft
• Years to refill this volume at a rate of 1,000
gallons per minute: 21,000 years
• Depletion is continuing

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2
• Recharge rate
• Cost (installation, equipment, energy,
maintenance)
• Long-term performance
• Water-quality of recharge water
• Water-quality changes in aquifer
• Flow of recharged water within aquifer
Artificial Recharge Viability Issues Artificial Recharge in Arkansas
• 1960’s: USGS conducts artificial recharge
study at Rice Experimental Station
• USGS concludes that recharge could be
done at a finite percentage of pumping rate
• Major factors affecting recharge:
– air entrainment
– sediment clogging
– chemistry
• Major deterrent: cost of water treatment
Background
• Bryan Huber
– Where idea originated
– Benefits to be derived
– Potential sources of recharge water
– Earlier attempt at recharging aquifer
• Cotton Inc. Core Funding
– Groundwater/surface water interaction
– Viability of surface water storage
Objectives
• Field test of viability of alluvial aquifer
recharge with groundwater
• Quantify water quality of potential
recharge sources
• Quantify efficacy of low-cost filtration
techniques
Study Site
• Poinsett County
• Largest rice producing
• Groundwater decline
Description of Recharge Test
• Monitor water levels from 4 observation
wells prior to, during, and after recharge
• Pump water from one well and recharge it
in another well ½ mile away
• Monitor pumping rate

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3
Recharge Test (Phase 1)
• Pump from well 1
• Inject in well 2 (about ½ mile from pumped
well)
• Monitor water levels before, during, and
after water injection
• Monitor flow rate, turbidity, and water
temperature
Pumping well
Recharge well
Flow meter
Turbidity sensor
Riser pipe
Test results
• Average
recharge rate:
565 gallons per
minute
• Water level rise
after 3.8 days:
38 ft (well 2); 0.7
ft (well 2A)
• Head space
remaining in
recharge well:
~80 ft 47
57
67
77
87
97
1/13 1/14 1/15 1/16 1/17 1/18 1/19 1/20 1/21
Date
Waterlevelabovetransducerinwell2,feet
44
44.5
45
45.5
46
46.5
47
Waterlevelabovetransducerinwell2A,feet
Water level in well 2
Water level in well 2A

4. 8/12/2014
4
44
45
46
47
48
49
50
51
52
53
54
1/17 1/18 1/18 1/19 1/19 1/20 1/20 1/21 1/21
Date
Waterlevelabovetransducerinwell2,feet
Water level in well 2
Water level in well 2A
Slope of recovery curve in
Well 2
Well 2
Well 2A
Well 2A Residual Water-Level Buildup
Well 2 Residual Water-Level Buildup
0
1
2
3
4
5
6
7
8
1 10 100 1000 10000
Time since recharge stopped, minutes
Residualwater-levelrise,feet
S= (2.5- 1.2) ft = 1.3
ft
T = 264 Q/S = 264 x 565 gpm/1.3 ft
= 114,700 gpd/ft
= 15,340 ft2/day
Test Summary
• Recharge well accepted water readily at
average rate of 565 gallons per minute
• Maximum water level rise was 38 feet
• Water level rise at 330 feet was 0.7 ft after 3.8
days of injection
• Transmissivity estimate was comparable to
values from tests in other wells
• Air entrainment not a large impediment to
recharge
• Recharge rate could be increased substantially
Water Quality
• Expense of water treatment
• Wetlands
• Filtration
• Reservoir construction
– 2000-2009: 111
– 2012: 30
– 2013: 54
Study Site
• 5 Ditch/Reservoirs
• Henry/Hilleman Silt
loam
• Nutrients
• Sediment
70 ac
1980s
140 ac
1980s
40 ac
2000s
40 ac
2000s
70 ac
2010s

5. 8/12/2014
5
Preliminary Results
• Statistically significant difference in means
p-value < 0.01
– Phosphates,Turbidity, TS
• Median % Reductions: 15%-70%
• Generalizations
– Size of ditch
– Seasonality
0.000
0.100
0.200
0.300
0.400
0.500
0.600
EDCBA
TotalSolids(g/L)
Site
Reservoir
Ditch
Filtration Test
Continued Effort
• Filtration testing
• Continued water
quality sampling
– Sediment
– Nutrients
– Metals
• Inventory of reservoirs
Acknowledgments
• Bryan Huber
• Cotton Inc.
• John Czarnecki
(University of Arkansas-
Little Rock)
• J.R. Rigby (USDA-ARS)
• Jerry Farris (Arkansas
State University)
• Cart Well, Inc.
• Depth to water: ~120 ft.
• Average unsaturated thickness: ~70 ft.
• Assumed specific yield: 0.20
• Storage per acre: 14 acre-ft
• Area of Huber farm: 1400 acres
• Aquifer storage: 19,600 acre-ft
• Time needed to fill at 500 gpm: 24 years!
Aquifer Storage Potential