growth, drought, and groundwater in texas... what are we learning?

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?