View
309
Download
0
Embed Size (px)
DESCRIPTION
69th SWCS International Annual Conference “Making Waves in Conservation: Our Life on Land and Its Impact on Water” July 27-30, 2014 Lombard, IL
Citation preview
8/12/2014
1
A Novel Test of Artificial Recharge in the Mississippi River Alluvial
Aquifer in Arkansas
Michele L. Reba, PhD, PEUSDA-ARS
Delta Water Management Research Unit
USDAPreserving 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
Arkansas4.5 million
Nebraska8.4 million
California7.3 million
Texas5.4 million
Water Quantity
Arkansas6.1 M acres farmed4.5 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
8/12/2014
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
8/12/2014
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
Wat
er lev
el a
bove
tran
sducer
in w
ell
2, f
eet
44
44.5
45
45.5
46
46.5
47
Wat
er
leve
l above
tra
nsd
uce
r in
wel
l 2A
, feet
Water level in well 2Water level in well 2A
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
Wat
er
lev
el a
bo
ve t
ran
sd
uce
r in
wel
l 2,
fee
t
Water level in well 2
Water level in well 2A
Slope of recovery curve inWell 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
Res
idu
al w
ater
-lev
el r
ise,
fee
t
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 ac1980s
140 ac1980s
40 ac2000s
40 ac2000s
70 ac2010s
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
Tota
l S
oli
ds
(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