Texas Bay and Estuary Texas Bay and Estuary Study ProgramStudy Program

Cindy Loeffler, ChiefCindy Loeffler, Chief

Water Resources Branch Water Resources Branch

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WMHS 602WMHS 602February 8, 2006February 8, 2006

FreshwaterInflows…

Salinity Nutrients

Sediments

…By DefinitionCreate and SustainEstuaries

TWC Section 11.147

Defines Beneficial Inflows As the “Salinity, Nutrient, and Sediment Loading Regime Adequate to Maintain an Ecologically Sound Environment in the Receiving Bay and Estuary System That Is Necessary for the Maintenance and Productivity of Economically Important and Ecologically Characteristic Sport or Commercial Fish and Shellfish Species and Estuarine Life Upon Which Such Fish and Shellfish Are Dependent.”

The Fundamental Scientific Basis of the Studies

The Fundamental Goal of the Recommendations

The Process of Developing FWI Recommendations

FWIRecommendations

Optimization Model

TxEMP

Hydrodynamic & ConservationTransport Model

TxBLEND

Hydrographic Survey

Nutrient Analysis

Sediment Analysis

Fisheries RegressionAnalysis

Objectives & Constraints

Fisheries Needs Analysis

Habitat Analysis

Hydrology

Verification

FWI Recommendations Are Based on the Biological Needs of aGroup of Target Species Expressed As A Statistical Relationship Between Harvest or Catch per Unit Effort And Inflow

H = 110.64 – 145.3*ln(QH = 110.64 – 145.3*ln(Qjfjf) + 332.5*ln(Q) + 332.5*ln(Qjaja) – 141.4*ln(Q) – 141.4*ln(Qsoso))

H = 3000.7 + 180.4*ln(QH = 3000.7 + 180.4*ln(Qmama) – 963.3*ln(Q) – 963.3*ln(Qmjmj) + 710*ln(Q) + 710*ln(Qjaja) )

- 231.5*ln(Q- 231.5*ln(Qsoso))

H = 32.786 + 0.0797*QH = 32.786 + 0.0797*Qmjmj + 0.2750*Q + 0.2750*Qjaja – 0.2010*Q – 0.2010*Qndnd

H = -18.087 + 0.2411*QH = -18.087 + 0.2411*Qjfjf – 0.1734*Q – 0.1734*Qmama + 0.0850*Q + 0.0850*Qndnd

ln(H) = 2.6915 – 0.7185*ln(Qln(H) = 2.6915 – 0.7185*ln(Qmama) + 1.86*ln(Q) + 1.86*ln(Qmjmj) – ) –

1.086*ln(Q1.086*ln(Qndnd))

ln(H) = 6.5679 + 0.6707*ln(Qln(H) = 6.5679 + 0.6707*ln(Qjaja) – 0.7486*ln(Q) – 0.7486*ln(Qsoso))

H = 545.59 + 160.9*ln(QH = 545.59 + 160.9*ln(Qjfjf) + 279.1*ln(Q) + 279.1*ln(Qmjmj) – 155.1*ln(Q) – 155.1*ln(Qjaja) )

- 277.9*ln(Q- 277.9*ln(Qndnd))

Blue Crab

Eastern Oyster

Red Drum

Black Drum

Spotted Sea-Trout

Brown ShrimpWhite Shrimp

Target Species:

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3

1.0

3

1.1

1.1

5

1.1

7

1.2

1.2

5

1.3

INFLOW (MILLIONS ACRE-FEET)

FIS

HER

IES H

AR

VEST

(MIL

LIO

NS L

BS)

TxEMPMODELSOLUTIONS

TPWD and TWDB Have Jointly Developed FWI Recommendations To Maintain the Health and Productivity of Texas Estuaries

TxEMP Is The Optimization Model That Produces a Range Of Inflows Within Which Estuarine Health and Productivity Needs May be Met

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3

1.0

3

1.1

1.1

5

1.1

7

1.2

1.2

5

1.3

INFLOW (MILLIONS ACRE-FEET)

FIS

HER

IES H

AR

VEST

(MIL

LIO

NS L

BS)

TxEMPMODELSOLUTIONS

MinQ Is the MinimumInflow That Maintains80% Of Mean HistoricHarvest and All OtherPhysical Constraints:Salinity, Nutrient, andSediment Needs

MaxH is FWI NecessaryTo Sustain Historic FisheriesHarvest as Evaluated AgainstExisting Fisheries Data ToMeet The Legislative Definition Of Beneficial Inflows

A Range Of Possible SolutionsLies Between Two Points AlongAn Optimization Curve:MaxQ and MinQ

0

50

100

150

200

250Thousa

nds

of Acr

e-F

eet

JAN

MAR

MAY

JUL

SEP

NO

V

MonthlyInflow Needs

FWI SeasonalDistribution

San Antonio Bay

The RecommendedFWI Is OftenExpressed As a Single AnnualizedNumber, ButAlways InfersThe Sum of Bi-Monthly Inflows

Delivery of Freshwater Inflows MustIncorporate Seasonality to Have AnyEcological Significance

FWIRecommendations

Summary: Methodology to Determine the Freshwater Inflows Necessary toMeet the Legislative Directive of TWC Section 11.147

Create Models That IntegrateDatasets and Predict Response To Varying Freshwater Inflows

Identify and Assemble DatasetsRepresentative of EstuarineEcosystem

Identify and AssembleDatasets That ReflectChanges in Inflows

Input Real DataInto Models AndAssess Projected Estuarine Conditions

Sabine9.5*

Galveston5.2

Matagorda2.0

San Antonio1.15

Aransas0.82

Nueces0.14

Laguna Madre0.25 * Millions of Acre Feet Per Year

Legislatively MandatedStudies to Determine“Beneficial Inflows”Necessary to ConserveHealth and ProductivityOf Texas Major EstuariesHave Been Completed. Some are Being Updated.

Galveston Bay

CaseStudy

Frame 001 22 Jul 2002 Finite Element GridFrame 001 22 Jul 2002 Finite Element Grid

Trinity River, Delta & BaySan Jacinto River & Buffalo Bayou

West Bay

East Bay

Gulf of Mexico

TxBLEND Hydrodynamic Model Grid for Galveston Bay and the Trinity-San Jacinto Estuary.

TxEMP MinQ and MaxH SolutionsTxEMP MinQ and MaxH Solutions

TxEMP Monthly Flow DistributionTxEMP Monthly Flow Distribution

TXBLENDTXBLEND Output Output

Monthly Salinity Monthly Salinity Maps Under Each Maps Under Each TxEMP SolutionTxEMP Solution

Salinity Difference Salinity Difference MapsMaps

Spatial Relationships Spatial Relationships of Modeled Salinity of Modeled Salinity Zones to Critical Zones to Critical Habitat AreasHabitat Areas

White Shrimp Abundance in White Shrimp Abundance in Galveston BayGalveston Bay

Higher Higher abundance abundance correlates with correlates with lower salinity lower salinity levelslevels

Galveston Bay Galveston Bay TXBLEND Time TXBLEND Time

SeriesSeries•Daily salinity at Daily salinity at a point in Upper a point in Upper Galveston BayGalveston Bay

•Predicted Predicted salinity within salinity within upper and lower upper and lower limits for MaxH limits for MaxH and MinQand MinQ

TxEMP MinQ and MaxH SolutionsTxEMP MinQ and MaxH Solutions

TPWD Recommendation

IMPLEMENTATION OF ENVIRONMENTAL FLOW NEEDS IN REGIONAL WATER PLANNING AND

FUTURE STATE WATER PERMITTING

Target Amount Historical Frequency Target Frequency** (Exceedence) (Exceedence) Above Normal Conditions [MaxH = 5.2 M Ac-Ft/Yr]* ~66% >50% Below Normal Conditions [MinQ = 4.2 M Ac-Ft/Yr]* ~70% >60% Dry Conditions [MinQ-Sal = 2.5 M Ac-Ft/Yr]* ~82% >75% Drought-of-Record [Min Historic = 1.8 M Ac-Ft/Yr]* ~98% >90% *Flows from Texas Water Development Board and Texas Parks & Wildlife; **Target Frequencies from Galveston Bay Freshwater Inflow Group (Region H)

Comparison of Model Solutions to Comparison of Model Solutions to Historical InflowsHistorical Inflows

“Nowhere in the World Has the Issue of Freshwater Inflow Been Studied So Systematically, or The Results Used to Guide Water Management Policies and Practices So Effectively, Than in the State of Texas.” – A Review and Application of Literature Concerning Freshwater Flow Management in Riverine Estuaries (2000), by Dr. E. Estevez, Director, Center for Coastal and Tropical Ecology, Mote Marine Laboratory, Sarasota, Florida.

Methods for Determining MinimumFreshwater Inflow Needs of TexasBays and Estuaries - Powell, Matsmuto, Brock. In Estuaries December 2002.

ReviewsReviews

“While the State of Texas has pioneered tools to address freshwater inflow needs for bays and estuaries, there are limitations to these tools in light of both scientific and public policy evolution.” – Science Advisory Committee to the Study Commission on Water for Environmental Flows, Interim Report to the 79th Legislature, December 2004

ReviewsReviews

Summary of Summary of SAC B&E SAC B&E comments comments

• Incorporate stakeholder input/peer review

• Commercial vs. independent fisheries data

• Improve statistical methods

• TPWD “Verification” analysis

• Optimum inflow vs. drought conditions

• Adaptive management and precautionary principle methods