growth, drought, and groundwater in texas... what are we learning?
DESCRIPTION
Presentation at the TWCA mid year conference 2012 www.twca.org James Beach LBG-Guyton AssociatesTRANSCRIPT
GROWTH, DROUGHT,
AND GROUNDWATERIN TEXAS…..
WHAT ARE WE LEARNING?
James Beach
LBG-Guyton Associates
Population Growth
The Census and Population Projections
License plates
Little league baseball
Texas Population
Confirmed sightings…..
Incomplete Sampling…..
2011 Texas Drought
New Data Pointworst 12-month drought on recordhottest reservoirs lowest since 1978huge agriculture lossesWater right calls - in East Texas!
Emergency calls“out of water” in 8-12 monthsPower and chemical plants, refineries
West Texas
New “Drought of Record”
Data Courtesy of
Year
Reality…. Shifted… (and Still Shifting)
West Texas Response It will rain and flood again – but until then -
expand the safety net
CRMWD – new wellfield and pipeline (no GCD)
Midland - new wellfield and pipeline (no GCD)San Angelo – new pipeline to existing wells
(long-term groundwater banking in GCD)
Odessa – assessing potential groundwater projects
Outcomes of the Situation Diversified water supply Drought-ready supply to augment surface
water Conjunctive use – good use of groundwater Potential to expand supplies through ASR
and brackish treatment Not inexpensive Similar approach as much of the desert
southwest
Important revelations
Current drought is “outside” of recorded water history
Not over yet
We have not recorded everything there is to see
There are serious implications of the new data
Texas Projected Need in Drought
Per Capita Surface Water Supply
Drought Sensitivity of Texas Aquifers
Drought Sensitivity - Major
Drought Sensitivity - Minor
Drought Impact on Groundwater Water levels declines in drought are
often related to increased pumping to meet peak demands – not long-term
Shallow outcrop wells can be sensitive to drought due to lack of local recharge
Deep wells are usually not impacted by drought
Aquifer Anatomy
Edwards Aquifer NOT a typical Texas Aquifer
Historic Spring Flows at Comal
the water table
unconfined and confined
Confined/Dipping Aquifer
Conceptual x-section
Page 25
Carrizo Aquifer Schematic
Gulf Coast
Carrizo-Wilcox Example
Page 28
Outcrop Well
Pumping Well
Middle Wilcox orSimsboro Aquifer
Outcrop
30 miles
Page 29
State Well Number, Screened Interval
Outcrop Well
Pumping Well
Outcrop and Downdip Hydrographsin Brazos and Robertson Counties
Dep
th t
o W
ater
(fe
et)
Page 30
Atascosa County Monitoring Wells
Monitoring Well
Carrizo-Wilcox
Volume in Storage ~ 50,000,000 AF in some counties –
How do we manage?
Stream-Aquifer Interaction and Drought1. Pumping from the shallow outcrop:
• May reduce water levels in the outcrop
• has the potential to impact streams (especially pumping close to streams)
2. Pumping from deep confined aquifer:• may not significantly reduce water levels in outcrop
• may not significantly impact streamflow
3. Historical data confirm this conclusion for Carrizo and Wilcox
4. Carrizo and Wilcox respond differently than the Edwards Aquifer
5. Most groundwater models don’t simulate this dynamic appropriately
Page 32
Aquifers and Drought Groundwater can offer a constant long-term
supply and/or a drought-ready safety net
Volumes stored in some aquifer are huge - and most are not sensitive to drought
Aquifers are not created the same – and they don’t respond the same to drought
The “same” aquifer can respond differently in different locations
Questions for you…..
Is there a new “Drought of Record” in your future?
Do you have a safety net?
Are we doing what we can to allow conjunctive use during droughts?
Questions for you…..
Is there a new “Drought of Record” in your future?
Do you have a safety net?
Are we doing what we can to allow conjunctive use during droughts?