the importance of groundwater surface water interaction - a case study on rio grande water supplies
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Presented by Ronald T. Green, Ph.D., P.G., F. Paul Bertetti, P.G., and Marques Miller at the Texas Water Conservation Association Conference in The Woodlands, Texas - March 2014TRANSCRIPT
Page 1
Texas Water Conservation Association70th Annual Convention
The Importance of
Groundwater/Surface Water Interaction:
A Case Study on Rio Grande Water Supplies
March 6, 2014
by
Ronald T. Green, Ph.D., P.G., F. Paul Bertetti, P.G., and Marques Miller
Geosciences and Engineering DivisionSouthwest Research Institute®
Page 2
Groundwater vs Surface Water in Texas
Surface water belongs to the state of Texas. It can be used by a landowner only with the state's permission.
Generally, groundwater belongs to the landowner. Groundwater is governed by the rule of capture.
There are exceptions…
"Underground water" means the water existing below the earth's surface, …does not include defined subterranean streams or the underflow of rivers (Texas Water Code)
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A Case Study on Rio Grande Water Supplies:
Devils River Basin, Texas
Page 4
Groundwater Recharge of the Lower Rio Grande
What is groundwater’s importance to the Lower Rio Grande?
Conveyance of groundwater/surface water in Devils River watershed
Importance of permeability architecture in Devils River to Rio Grande
Page 5
Amistad Reservoir Water Budget
Lake Amistad
DevilsRiver
PecosRiver
Rio Grande at Langtry
San FelipeCreek
Rio Grande below Amistad Dam
CienegasCreek
Gauging Station
GoodenoughSpring
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Amistad Reservoir Water Budget (acre-ft/yr)
Lake Amistad
DevilsRiver
263,000
PecosRiver
195,000
Rio Grande at Langtry1,071,000
San FelipeCreek65,000
Rio Grande below Amistad Dam1,659,000
Rio Grande at Del Rio1,659,000
CienegasCreek8,700
Gauging Station
GoodenoughSpring 103,000
Lower Rio Grande gets 1/3 of its water from Val Verde County
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How is Water Conveyed through the Devil’s River Watershed?
Sutton County - Standen A. and P. Kirby, 2009Crockett County - Inglehart, H.H. 1967Val Verde County - Reeves, R.D. and T.A. Small. 1973.
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Where are the High Capacity Wells in the Devils River Watershed?
TWDB well driller reports: 752 wells with measured capacity
High capacity water wells are
only located near river channels
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0 2 4 6 8 10 12 14 160
500
1,000
1,500
2,000
2,500
3,000
Distance from Closest River Channel (mi)
We
ll P
um
p R
ate
(g
pm
)
Distance from River Channel versus Well Capacity
Virtually all wells with capacity of 500 gpmare within 1.5 miles of a river
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Development of Karst Conduits in Edwards-Trinity Aquifer
Slightly acidic rain water funneled into existing river channels as the Edwards Plateau was raised.
This mechanism resulted in development of preferential flow paths (i.e., conduits) in river channels.
In contrast, conduit development in the Edwards Aquifer was pervasive because it was not exhumed (raised) similar to the Edwards Plateau.
Woodruff and Abbott, 1979, 1986What this means is that you cannot assume you have high capacity wells everywhere in the Edwards-Trinity
Aquifer just because you happen to have a high-capacity well that’s near a river channel
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Refined Characterization of Devils River Watershed Hydrogeology
Water is conveyed through Devils River watershed as both groundwater (particularly in the upper reaches) and as surface water (in the lower reaches).
Texas water law struggles with groundwater/surface water relationship, but reality insists it be recognized.
Dye tracer tests in Sonora confirm the presence of conduits in
Devils River channel
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How is Groundwater Flow Currently Characterized?
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Permeability Structure of the Edwards-Trinity Aquifer
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Refinement of Hydrogeology of Devils River Watershed
Mapped geology of Devils River watershed
TWDB GAM of Devils River watershed
hydrogeology
Refined characterization ofDevils River watershed
hydrogeology
The 2010 TWDB Groundwater Availability Model (GAM)does not characterize groundwater flow associated with the river channels as subterranean streams or river underflow
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Reclassification of Groundwater Conveyance in the Devils River Watershed
If groundwater conveyance in the Devils River watershed is classified as “subterranean streams or the underflow of rivers”,
then groundwater conveyance could be governed as surface water and not by the rule of capture.
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What Are the Consequences if Devils River Watershed Groundwater is Governed by the Rule of Capture?
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Amistad Reservoir Water Budget
Lake Amistad
DevilsRiverPecos
River
Rio Grande at Langtry
San FelipeCreek
Rio Grande below Amistad Dam
Rio Grande at Del Rio
CienegasCreek
Gauging Station
GoodenoughSpring
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Amistad Reservoir Water Budget (acre-ft/yr)
Lake Amistad
DevilsRiver
263,000
PecosRiver
195,000
Rio Grande at Langtry1,071,000
San FelipeCreek65,000
Rio Grande below Amistad Dam1,659,000
Rio Grande at Del Rio1,659,000
CienegasCreek8,700
Gauging Station
GoodenoughSpring 103,000
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Experience of Historical Groundwater Exploitation
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Amistad Reservoir Water-Budget Analysis (acre-ft/yr)
Groundwater DischargeAmistad Reservoir
(1961-1967)
Pecos River 32,000Goodenough Spring 89,000Devils River 240,000San Felipe Springs 58,000Minor springs on the Rio Grande 2,000Unmeasured springs on the Rio Grande 81,000Total 502,000
Reeves, R.D. and T.A. Small. 1973. Groundwater Resources of Val Verde County, Texas. Report 172. Texas Water Development Board.
Groundwater DischargeAmistad Reservoir
(1961-2000)
Pecos River 194,000Goodenough Spring 103,000Devils River 264,000San Felipe Springs 65,000Cienegas Creek 8,700Unmeasured springs Rio Grande -Total 634,000
Data from IBWC website 1961-2000
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Amistad Reservoir Water Budget (acre-ft/yr)(1961-2000)
Lake Amistad
DevilsRiver
263,000
PecosRiver
195,000
Rio Grande at Langtry1,071,000
San FelipeCreek65,000
Rio Grande below Amistad Dam1,659,000
Rio Grande at Del Rio1,659,000
CienegasCreek8,700
Gauging Station
GoodenoughSpring 103,000
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Lake Amistad
DevilsRiver
263,000
PecosRiver
195,000-?
32,000
Rio Grande at Langtry1,071,000
San FelipeCreek65,000
Rio Grande below Amistad Dam1,659,000 1,496,000
Rio Grande at Del Rio1,659,000 1,496,000
CienegasCreek8,700
Historical Impact of Pumping on Amistad Reservoir Water Budget (acre-ft/yr)
Pecos River Discharge (1961-1967)
Gauging Station
GoodenoughSpring 103,000
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Potential Impact of Pumping on Amistad Reservoir Water Budget (acre-ft/yr)
from Three Proposed Projects
150,000 acre-ft/yr
49,000 acre-ft/yr
93,826 acre-ft/yr
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Potential Impact of Pumping on Amistad Reservoir Water Budget (acre-ft/yr)
from Three Proposed Projects
Lake Amistad
DevilsRiver
263,000-150,000 83,000
PecosRiver
195,000 -49,000146,000
Rio Grande at Langtry1,071,000
San FelipeCreek65,000
Rio Grande below Amistad Dam1,659,000 1,460,000
Rio Grande at Del Rio1,659,000 1,460,000
CienegasCreek8,700
Gauging Station
GoodenoughSpring 103,000
SycamoreCreek
-93,826?
1,460,000 1,366,000
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Recharge/groundwater/surface water are intrinsically linked in a watershed that recharges Amistad Reservoir
Conveyance of water through Devils River watershed is facilitated by development of conduits coincident with river channels
Other Edwards Plateau watersheds show similar characteristics
Can this conduit system be defined as subterranean streams or the underflow of rivers?
This presentation provides a clear example of how a technical study can be used to frame regulatory governance of a water resource
Summary
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Acknowledgement
Funding for water resource assessment of Devils River watershed provided by the
Coypu Foundation
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Contact Information
Ronald T. Green, Ph.D., P.G.
Institute Scientist
Geosciences and Engineering Division
Southwest Research Institute
6220 Culebra
San Antonio, Texas 78238
1.210.522.5305 (office)
1.210.522.5184 (fax)
1.210.316.9242 (cell)