Groundwater Availability Model (GAM) for the Yegua-Jackson … · 2011-10-26 · Groundwater...

Groundwater Availability Model (GAM) for the

Yegua-Jackson Aquifer

Stakeholder Advisory Forum (SAF#1)College Station, Texas

June 24h, 2008

Cindy RidgewayVan Kelley and Neil Deeds

Outline• General Introduction to the GAM program• Introduction to the Yegua-Jackson GAM team• Yegua-Jackson regional overview• Basics of groundwater flow• Overview of Yegua-Jackson Aquifer• Numerical groundwater modeling and the GAMs• Data collection• GAM schedule

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Region F Brazos G

Panhandle

Far West Texas

Region C

East Texas

Region H

Llano Estacado

Plateau

Rio Grande

South Central Texas

Region B

Coastal Bend

Lower Colorado

North East Texas

Lavaca

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GF

Groundwater Availability Modeling

Texas Water Development Board

Cindy Ridgeway

Contract Manager

Yegua-Jackson Aquifer “GAM”

• Purpose: to develop tools that can be used to help GCDs, RWPGs, and others understand and manage their groundwater resources.

• Public process: you get to see how the model is put together.

• Freely available: models are standardized, thoroughly documented. Reports available over the internet.

• Living tools: periodically updated.

What is the gamprogram?

• GCDs, RWPGs, TWDB, and others collect new information on aquifer.

• TWDB plans to update GAMs every five years with new information.

• Please share information and ideas with TWDB on aquifers and GAMs.

Livingtools

• The model– predict water levels and flows in response to

pumping and drought– effects of well fields

• Data in the model– water in storage– recharge estimates– hydraulic properties

• GMAs, GCDs and RWPGs can request runs

How do weuse GAM?

• Water Code & TWDB rules require that GCDs use GAM information, if available, for their management plans.

• TWDB rules require that RWPGs use managed available groundwater estimates, if developed in time for the planning cycle

Do we haveto use GAM?

• Managed available groundwater (MAG)…the amount of groundwater available for use.

• The State does not directly decide how much groundwater is available for use: GCDs will through GMA process.

• A GAM is a tool that can be used to assess groundwater availability once GCDs and GMAs decide on the desired future condition of the aquifer.

What isGroundwater

Availability or MAG?

• Stakeholder Advisory Forums (SAF)– hear about progress on the model– comment on model assumptions– offer information (timing is important!)

• Report review– at end of project

• Contact TWDB– contract manager

Participating inthe GAM process

Comments:Cindy Ridgeway

[email protected](512)936-2386

Texas Water Development Board1700 North Congress Avenue

P.O. Box 13231Austin, Texas 78711-3231

Web information:www.twdb.state.tx.us/gam

Outline

• General Introduction to the GAM program• Introduction to the Yegua-Jackson GAM team• Yegua-Jackson regional overview• Basics of groundwater flow• Overview of Yegua-Jackson Aquifer• Numerical groundwater modeling and the GAMs• Data collection

Yegua-Jackson GAM Team Primary Roles

• INTERA– Project management– SAF meetings– Heads and calibration targets– Recharge implementation– Surface water / groundwater

interaction– Pumping data and

implementation– Water quality– Model

construction/calibration/SA– Project reporting/deliverables

• Baer Engineering (Paul Knox)– Geology/structure

• URS (Steve Young)– Aquifer Properties

• Graham Fogg– Senior Technical Review

Webb Duval

Harris

Frio

Kenedy

Polk

Starr

Bee

Leon

Hidalgo

Tyler

Brazoria

La Salle

Liberty

Milam

Lee

Nueces

Zapata

Matagorda

Houston

Jasper

Kleberg

Cameron

Hardin

Brooks

Lavaca

Atascosa

Goliad

Wharton

Fayette

De Witt

Calhoun

Newton

Live Oak

Jefferson

Wilson

Jim Hogg

Victoria

McMullen

Tr inity

Walker

Bastrop

Gonzales

Grimes

Willacy

Colorado

Karnes

Refugio

Austin

Jackson

Angelina

Jim Wells

Fort BendGalveston

Montgomery

Brazos

Chambers

Robertson

Waller

Sabine

Burleson

Guadalupe

Caldwell

AransasSan Patricio

Madison

San Jacinto

Washington Orange

Nacogdoches

Dimmit

San Augustine

Cherokee

Aquifer Outline

State Line

County Boundaries

Tentative Study Area Source: Online: Texas Water Development Board, March 2007

−0 20 40

Miles


14

16

15

13

12

11

8

State Line

County Boundaries

GMAs8

10

11

12

13

14

15

16 Source: Online: Texas Water Development Board, March 2007

0 20 40

Miles

10GMAs

Source: Online: Texas Water Development Board, March 2007

0 20 40

Miles

Barton Springs/Edwards Aquifer CDBee GCDBluebonnet GCDBrazoria County GCDBrazos Valley GCDClearwater UWCDCoastal Bend GCDCoastal Plains GCDColorado County GCDCorpus Christi ASRCDEdwards Aquifer AuthorityEvergreen UWCDFayette County GCDFort Bend Subsidence DistrictGuadalupe County GCDGonzales County UWCDHarris-Galveston Coastal Subsidence DistrictNeches & Trinity Valleys GCDPost Oak Savannah GCDSan Patricio County GCD

Goliad County GCDKenedy County GCDLive Oak UWCDLone Star GCDLost Pines GCDLower Trinity GCDMcMullen GCDMedina County GCDMid-East Texas GCDPecan Valley GCDPineywoods GCDPlum Creek CDRed Sands GCDRefugio GCDRusk County GCDSoutheast Texas GCDStarr County GCDTexana GCDVictoria County GCDWintergarden GCD

GCDs

Nueces

Brazos

NechesTrinity

San Jacinto

Lavaca

Nueces-Rio Grande

Guadalupe

Rio Grande

Sabine

Colorado

San Antonio

San Antonio-Nueces

Neches-Trinity

Brazos-Colorado

San Jacinto-Brazos

Colorado-Lavaca

Lavaca-Guadalupe

State Line

County Boundaries Source: Online: Texas Water Development Board, March 2007

0 20 40

Miles

River Basins

Study Area

State Line

County Boundaries

RWPGsRegionName

Brazos G

Coastal Bend

East Texas

Lavaca

Lower Colorado

Region C

Region H

Rio Grande

South Central Texas Source: Online: Texas Water Development Board, March 2007

−0 20 40

Miles

RWPGs

State Line


−0 20 40

Miles

Elevation (ft amsl)

-9 - 0

1 - 75

76 - 150

151 - 225

226 - 300

301 - 375

376 - 450

451 - 525

526 - 600

601 - 675

676 - 750

Topography

State Line

County Boundaries

Study Area Source: Online: Texas Water Development Board, March 2007

0 20 40

Miles

Average AnnualPrecipitation

(in/yr)20 - 2526 - 3031 - 3536 - 4041 - 4546 - 5051 - 5556 - 6061 - 65

AveragePrecipitation

Study Area

State Line


0 20 40

Miles

Average AnnualTemperature

(oF)68

70

72

74

76

AverageTemperature

Groundwater Flow - Definitions• Aquifer – Water saturated permeable geologic

unit that can transmit significant quantities of water (e.g., sands & gravels).– Unconfined – water table forms the upper boundary– Confined – has overlying/underlying lower

permeabilty layers• Water table – The top of the saturated zone.• Hydraulic head – The water level in a well

expressed as an elevation.

Groundwater Flow – Definitions (cont’d)

• Hydraulic conductivity (permeability) – A physical property of the geologic media representing its ability to transmit water.

• Specific yield – The volume of water that an unconfined aquifer releases from storage per unit surface area of aquifer per unit decline in water table elevation.

• Storativity – The volume of water that a confined aquifer releases from storage per unit surface area of aquifer per unit decline in head.

Groundwater Flow – Definitions (cont’d)

• Recharge – The entry of water to the saturated zone at the water table:

Recharge = (precipitation + stream loss) minus (runoff + evapotranspiration).

• Cross-formational flow – Groundwater flow between separate geologic formations.

• Stream losses or gains – The water that is either lost or gained through the base of the stream or river.

Basic Principles of GW Flow• The primary observable quantity describing

groundwater flow is the water level as measured in a well.

• The water level expressed as elevation is termed the hydraulic head.

• The difference in hydraulic head between adjacent wells determines the direction of GW flow (from higher heads towards lower heads).

• The water table is typically a subdued replica of the topography.

Basic Principles of GW Flow (cont’d)

• The thickness and hydraulic conductivity of the aquifer material define volumetric flow rates (e.g., for pumping)– The larger the hydraulic conductivity and

thickness, the greater the flow.

Schematic Cross Section of Groundwater Flow

Confined Aquifer

AquiferConfining Unit

Water Table

Webb Duval

Harris

Fr io

Kenedy

Polk

Starr

Bee

Leon

Hidalgo

Tyler

Brazoria

La Salle

Liberty

Milam

Lee

Nueces

Zapata

Matagorda

Houston

Jasper

Kleberg

Cameron

Hardin

Brooks

Lavaca

Atascosa

Goliad

Wharton

Fayette

De Witt

Calhoun

Newton

Live Oak

Jefferson

Wilson

Jim Hogg

Victoria

McMullen

Trinity

Walker

Bastrop

Gonzales

Grimes

Willacy

Colorado

Karnes

Refugio

Austin

Jackson

Angelina

Jim Wells

Fort BendGalveston

Montgomery

Brazos

Chambers

Robertson

Waller

Sabine

Burleson

Guadalupe

Caldwell

AransasSan Patricio

Madison

San Jacinto

Washington Orange

Nacogdoches

Dimmit

San Augustine

Cherokee

Aquifer Outline

State Line

County Boundaries

Tentative Study Area Source: Online: Texas Water Development Board, March 2007

−0 20 40

Miles


• Considered a minor aquifer in Texas as of the 2002 State Water Plan

• Exists primarily in the outcrop and near-outcrop regions of the Yegua Formation and Jackson Group

Stratigraphic Column

Series Group Formation Oligocene Catahoula Eocene-

Oligocine Whitsett

Manning Wellborn Upper

Jackson

Caddell

Yegua

Terti

ary

Eocene

Middle Upper Claiborne Cook

Mountain

Yegua-Jackson Structure• Structure completed for the TWDB by

INTERA and Baer Engineering in 2007• Divided into four units

– Upper Jackson– Lower Jackson– Upper Yegua– Lower Yegua

• Also mapped– Net sand– Depositional Environments– Faults

LegendYegua-Jackson outcropState LineCounty BoundariesWell LocationsCross-Sections (DIP)Cross-Sections (STRIKES A and B)Cross Section (STRIKE C)

0 40 8020Miles

124

3

5

6

7

89

10

1112

13

14

1516

17

18

19

20

21

22

23

24

25

2627

28

29

30A B C

B'

A', C'Cross-Section

Base Map

Example Dip SectionLeon, Madison, Walker, Montgomery, Harris Counties

LegendYegua-JacksonSalt and Shale FeaturesCretaceous Shelf MarginsShelf EdgeControl Points (wells)

Elevation (ft amsl)-5,650 - -5,000-4,999 - -4,000-3,999 - -3,000-2,999 - -2,000-1,999 - -1,000

-999 - 01 - 1,000

0 20 40 60 8010Miles

Upper JacksonStructure

750

250

1000

500

250

500

500

250

750

750

250

250

1000

750

750

1000

500

500

250

500

250

1000

750

250

500

LegendState LineShelf EdgeYegua-Jackson outcropCounty BoundariesWell Locations

Upper Yegua Isopach (ft)10 - 250251 - 500501 - 750751 - 1,0001,001 - 1,2501,251 - 1,500

0 40 8020Miles

Sediment Input Axis(Size Relative to Sed. Vol.)

Upper Yegua

Isopach

200

300

100 0

100

00

100

0

0

200

00

200

0

100

010

0

0

0

0

0

200

0

0

100

100

100

0

300

100

100

0

0

100

0 40 8020Miles

LegendYegua-Jackson outcropShelf EdgeWell Locations

Upper Jackson - Sand Thickness0

1 - 100101 - 200201 - 300301 - 400401 - 500


Upper Yegua

Net Sand

LegendState LineShelf EdgeYegua-Jackson outcropCounty BoundariesWell Locations

FaciesFluvialFloodplain < 50'Deltaic/Delta Front/StrandplainDistal DeltaDelta Margin < 50'ShelfShelf ChannelSlopeShelf/Slope Sand > 50'

0 20 40 6010Miles


Upper YeguaFacies

Outline• General Introduction to the GAM program• Introduction to the Yegua-Jackson GAM team• Yegua-Jackson regional overview• Basics of groundwater flow• Overview of Yegua-Jackson Aquifer• Numerical groundwater modeling and the

GAMs• Data collection• Identification of data needs• GAM schedule

Definition of a Model

Domenico (1972) defined a model as a representation of reality that attempts to explain the behavior of some aspect of reality and is always less complex than the real system it represents

Wang & Anderson (1982) defined a model as a tool designed to represent a simplifiedversion of reality

Why Groundwater Flow Models?

• In contrast to surface water, groundwater flow is difficult to observe

• Aquifers are typically complex in terms of spatial extent and hydrogeologicalcharacteristics

• A groundwater model provides the only means for integrating available data for the prediction of groundwater flow at the scale of interest

Numerical Flow Model

• A numerical groundwater flow model is the mathematical representation of an aquifer

• It uses basic laws of physics that govern groundwater flow

• In the model domain, the numerical model calculates the hydraulic head at discrete locations (determined by the grid)

• The calculated model heads can be compared to hydraulic heads measured in wells

Define model objectives

Data compilation and analysis

Conceptual model

Calibration

Reporting

Verification

Future WaterStrategies

Prediction

Comparisonwith

field data

Model design

Field data

Field data

*Includes sensitivity

analysis

Modeling Protocol

Transient*

Steady State*

Start with a conceptual model

West East

Irrigationreturn flow

Enhancedrecharge beneathagricultural area

Spring

Dryspring

Escarpmentspring

Divide it up into cells

West East

Irrigationreturn flow

Enhancedrecharge beneathagricultural area

Spring

Dryspring

Escarpmentspring

Model Grid Scale

BRAZOS

GRIMES

BURLESON

ROBERTSON

MADISON

WASHINGTON

LEON

MILAM

Source: N/A

0 2.5 5 7.5 10

Miles

−

Model Layering

Series Group Formation Model LayerOligocene Catahoula 1* Eocene-

Oligocine Whitsett

Manning 2

Wellborn Upper Jackson

Caddell 3

4 Yegua 5

Terti

ary

Eocene

Middle Upper Claiborne Cook

Mountain

*in the outcrop, Layer 1 simulates the surficial aquifer

GAM Model Specifications• Three dimensional (MODFLOW-2000)• Regional scale (1000’s of square miles)• Grid spacing

– Uniform grid of 1 square mile or less– Yegua Jackson will be 1 square mile

• Implement– recharge– groundwater/surface water interaction– pumping

• Calibration to observed water levels/fluxes

MODFLOW

• Code developed by the U.S. Geological Survey• Selected by TWDB for all GAMs• Handles the relevant processes• Comprehensive documentation• Public domain – non-proprietary• Most widely used groundwater model

– USGS had 12,261 downloads of MODFLOW computer code in 2000

• Supporting interface programs available– Groundwater Vistas to be used in all GAMs

Data CollectionKey Data Sources

• Heads– County Reports (predevelopment)

• Evidence of artesian wells• Evidence of flowing springs

– TWDB groundwater database– GCDs?

• Water quality– TWDB groundwater database


• Fluxes– Baseflow

• Slade et al. (2002) gain-loss studies• Hydrograph separation analysis• San Antonio River Authority, Evergreen Underground

WCD, and Goliad GCD sponsoring groundwater-surface water interaction study on the Lower San Antonio River with the USGS.

– Springs• Brune (1981)• TWDB database


• Hydraulic Properties– County reports– Meyer– PWS Database– TCEQ Surface Casing Database

• Typically specific capacity tests– GCDs– Stakeholders

Outline

• General Introduction to the GAM program• Introduction to the Yegua-Jackson GAM team• Yegua-Jackson regional overview• Basics of groundwater flow• Overview of Yegua-Jackson Aquifer• Numerical groundwater modeling and the GAMs• Data collection• GAM schedule

Schedule2008 2009 2010 Project Task

J F M A M J J A S O N D J F M A M J J A S O N D J F

1.0 Project Management

1.1 Monthly Status Report 1.2 TWDB Review Meetings 1.3 Senior Technical Review 2.0 Stakeholder Communication 2.1 Stakeholder Interaction 2.2 SAF Meeting 2.3 Stakeholder and TWDB Seminar 3.0 Model Development 3.1 Data Collection and Conceptual Model 3.2 Model Design 4.0 Model Calibration 4.1 Steady-State Calibration 4.2 Transient Calibration 4.3 Sensitivity Analysis 5.0 Documentation & Tech. Transfer 5.1 Data Model Documentation 5.2 Reporting

CM DM FM

Monthly Report CM Conceptual Model Report (3/5/09) DM Draft Model Report (10/1/09)

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Meeting Minutes for the First Yegua-Jackson Groundwater Availability Model (GAM)

Stakeholder Advisory Forum (SAF) Meeting June 24, 2008

Vegetable and Fruit Improvement Center, Suite 120, Bldg A College Station, Texas

The first Stakeholder Advisory Forum (SAF) Meeting for the Yegua-Jackson Groundwater Availability Model (GAM) was held on Tuesday, June 24th, 2008 at 1:00 PM at the Texas A&M Vegetable and Fruit Improvement Center located at 1500 Research Parkway in College Station. A list of meeting participants is provided at the end of these meeting notes. The primary purpose of the first SAF meeting was to provide an introduction to the Yegua-Jackson GAM Team and their proposed approach to developing the model and to solicit input from stakeholders including any available data that could be made public. The meeting also provided a forum for discussing the project schedule and provided an opportunity for feedback from stakeholders.

Meeting Introduction: Cindy Ridgeway, TWDB

The meeting was initiated by Ms. Cindy Ridgeway of the Texas Water Development Board (TWDB). She gave a brief introduction to the GAM Program and discussed how GAMs are used in Texas water resources planning. She then discussed GAMs and how they relate to Managed Available Groundwater as well as the importance of the stakeholder process.

SAF Presentation: Neil Deeds and Van Kelley, INTERA Inc Neil Deeds and Van Kelley (INTERA) presented a prepared presentation structured according to the following outline:

1. Introduction To Yegua-Jackson Team 2. Yegua-Jackson Regional Overview 3. Basics of Groundwater Flow 4. Overview of Yegua-Jackson Aquifer 5. Numerical Groundwater Modeling and the GAMs 6. Data Collection/Data Needs 7. GAM Schedule

The presentation is available on the GAM website:

(http://www.twdb.state.tx.us/gam/ygjk/ygjk.htm)

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http://www.twdb.state.tx.us/gam/ygjk/ygjk.htm

Questions and Answers: Cindy Ridgeway (TWDB) Presentation:

Q: Does the TWDB send GCDs updates automatically when the revise or update a

GAM? A: Yes, modifications to GAMs are communicated to GCDs through email with

major updates also being mailed to the GCD with the model files and documentation.

Q: What is the status of the Gulf Coast GAM? A: Cindy gave a description of the new approach to determining the Gulf Coast

structure statewide, and indicated that this new structure would be used when the Gulf Coast GAMS were updated.

Q: Can GCDs perform their own GAM simulations to support planning or the GMA

process thereby bypassing a request of the TWDB to perform the simulations? A: Yes, a GCD can perform their own simulations. However, if the simulations are

going to be used to support a Desired Future Condition, they have to document the simulation very well for the TWDB and they have to provide the model input and output files to the TWDB for their review. The only drawback is that the GCD will have to bear the cost of performing the simulations if they do not use the TWDB.

Q: When can a GCD expect to receive the GAM water balance from the TWDB to

be used to support their Management Plan? A: A GCD should receive the water balance information for their GCD to support

the Management Plan at least 3 to 6 months prior to the due date for the plan to be submitted to the TWDB.

Questions and Answers: Van Kelley and Neil Deeds (INTERA) Presentation: Q During the presentation of the aquifer study area it was asked if the aquifer

actually extended below the Gulf Coast Aquifer? And if so, do we need to be worried about Gulf Coast Aquifer injection wells?

A: The formations which are equivalent to those that comprise the Yegua-Jackson Aquifer do extend below the Gulf Coast Aquifer but at depths much greater than the extent of freshwater or even brackish water in the aquifer. Because of faulting and the lower energy depositional nature (finer-grained) of gulf coast formations as they extend gulfward (i.e., deeper), they are very poorly connected to the freshwater portions of the aquifers. The bulk of the potable Yegua-Jackson Aquifer is constrained to the outcrop.

Q: There are potable confined wells producing in Grimes County and in Lafayette

Counties. A: The modeling team would like to know where these wells are so we can make sure

that the GAM appropriately captures the confined portions of the aquifer as being

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well connected to the outcrop. In developing the Yegua-Jackson structure, it was noted that there were portions of the aquifer where potable groundwater existed in confined portions of the aquifer. For each control well, we made estimates of fresh groundwater versus brackish and saline groundwater. We could map a depth to freshwater surface.

It was requested that INTERA develop a depth to poor groundwater quality for the upper and lower Yegua and Jackson aquifer units and post it on the TWDB website.

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Yegua-Jackson Aquifer GAM Stakeholder Advisory Forum 1

June 24, 2008

Attendance

Name Affiliation Kip Brunner Fayette Water Supply David A. Van Dresar Fayette County GCD

Lloyd A. Behm Bluebonnet GCD

Marius Jigmond TWDB

Wade Oliver TWDB

Van Kelley INTERA

Neil Deeds INTERA

Cindy Ridgeway TWDB

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