1. The State Methodology for determination of freshwater inflow needs of the Texas bays

2. The State Methodology for determination of freshwater inflow needs of the Texas bays
Overview & Critique
Presentation to:
Science Advisory Committee
Study Commission on Water for Environmental Flows
18 June 2004
George H. Ward
Center for Research in Water Resources University of Texas at Austin

3. Sabine Lake
Galveston Bay
Matagorda Bay
San Antonio Bay
Aransas-Copano Bays
Corpus Christi Bay
Upper Laguna Madre- Baffin Bay
Lower Laguna Madre

4. ESTUARY coastal waterbody semi-enclosed free connection to open sea
influx of sea water
freshwater influx
small to intermediate scale

8. transitional systems, between freshwater and marine
ESTUARIES
transitional systems, between freshwater and marine
transitional systems, between freshwater and marine
hydrography and chemical qualities governed by both terrestrial and marine controls, as well as factors unique to estuary
hydrography and chemical qualities governed by both terrestrial and marine controls, as well as factors unique to estuary
terrestrial controls: freshwater influxes, flooding and inundation, runoff and inflow loads (sediment, nutrients, pollutants), and atmospheric deposition
terrestrial controls: freshwater influxes, flooding and inundation, runoff and inflow loads (sediment, nutrients, pollutants), and atmospheric deposition
marine controls: tides, waves, non-astronomical sea-level variations, marine storms, salinity, and littoral sediment influx
marine controls: tides, waves, non-astronomical sea-level variations, marine storms, salinity, and littoral sediment influx
predominance of these factors depends upon position in estuary: pronounced environmental gradients
predominance of these factors depends upon position in estuary: pronounced environmental gradients
extreme time variability in estuary
extreme time variability in estuary

9. cross section view (longitudinal-vertical)
plan view (surface horizontal)

10. ESTUARIES wide range in habitats spanning the estuarine zone
majority of the larger animals in estuary only temporarily for specific biological purposes

12. ESTUARIES wide range in habitats spanning the estuarine zone
majority of the larger animals in estuary only temporarily for specific biological purposes
complex and shifting food webs, with frequent overlap between planktonic, pelagic and benthal communities
substantial time variations in all of above factors, resulting in marked variability in community make-up and abundance
abundance of specific organism depends on:
population capable of entering system (i.e., abundance/health of source population, and capability to negotiate entrance into the system)
availability of suitable physico-chemical conditions and/or food sources

14. This sequence of slides is an attempt to capsulize the entire estuarine ecosystem.
This first slide displays the major biological communities, with flora as the base of the ecosystem, and the consumer communities somewhat eccentrically subdivided into those that are eaten by humans ("seafood organisms") and those that are not ("non-fishery consumer"). In the estuary, immigration from the sea, "recruitment", is a major determinant of the communities within the bay, but, of course, shrimp people are very familiar with this.

15. This couples the chemical environment with the biological
This couples the chemical environment with the biological. Light and nutrients are of course the primary controls on flora, light being modulated by suspended matter, of particular potential importance in our project area because of the large sediment loads. Among the "other constituents", most important is dissolved oxygen, which is given more attention later. It's noteworthy at this point that the diagram applies as well to a shrimp pond, if "recruitment" is generalized to include stocking, and "other constituents" includes feeding.

16. The major complexity of the estuarine ecosystem is the processes that control the concentrations and distribution of chemical parameters within the system, shown here. While no one really cares about estuary circulation (a.k.a. hydrodynamics) as a management endpoint, it must be addressed to understand the distribution of waterborne parameters, which usually are the management endpoint. Note that any one of these major boxes could be considerably expanded.

19. Potential freshwater inflow effects on estuary
dilutes seawater 
carries nutrients, trace constituents, and terrestrial sediments into estuary 
contributes to gradient of water properties across estuary 
produces inundation and flushing of important zones, due to short-term flooding 
variability over time creates fluctuation in estuarine properties, important to ecosystem function 
source of renewal water

27. STATE METHODOLOGY FOR DETERMINING INFLOW REQUIREMENTS OF THE TEXAS BAYS
An overview & summary

28. San Antonio Bay

30. OPTIMAL INFLOWS FOR SAN ANTONIO BAY

31. OPTIMAL INFLOWS FOR GALVESTON BAY

34. Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Min Q Specification
Objective goal: Minimal total annual inflows

36. Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Constraints:
Monthly inflow: >lower decile (10th percentile)
<historical monthly median
Bimonthly inflows:>specified values (>sum of lower decile values)
Salinity: bounded by “consensus” viability limits
Min Q Specification
Objective goal: Minimal total annual inflows
Harvest: >80% of historical mean for each species

37. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES

38. For San Antonio Bay, the 7 key species are:
blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout

39. For Galveston Bay, the 8 key species are:
blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout flounder

40. For Sabine Lake, the 8 key species are:
blue crab brown shrimp
menhaden white shrimp
red drum croaker
spot speckled trout

41. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
ABUNDANCE IS PROPORTIONAL TO, HENCE MEASURED BY, THE ANNUAL COMMERCIAL HARVEST

42. Advantages of harvest as a measure of abundance:
 the data are quantitative and consistently measured
 the data represent the catch integrated over large aquatic areas, so the effect of spatial variability should be averaged out
 a long period of record of annual harvests is available extending back in some cases five decades
 the harvest measures one of the direct economic benefits of the resource of an estuary

43. Disadvantage of harvest as a measure of abundance:
Harvest is affected by factors having no relation to abundance:
 regulation of the fishery
 location, catch and processing technology of the fleet
 skill of the fisherman
 market and economics
 external stresses on the species population

44. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
ABUNDANCE IS PROPORTIONAL TO, HENCE MEASURED BY, THE ANNUAL COMMERCIAL HARVEST
ABUNDANCE IS QUANTIFIED ENTIRELY BY 6 BIMONTHLY FLOWS, TOTALLED OVER THE ENTIRE BAY

45. 6 independent flow variables ( “seasonal” flows):
Jan + Feb Mar + Apr
May + Jun Jul + Aug
Sep + Oct Nov + Dec
each computed by:
Inflow = Gauged + Ungauged - Diversions + Returns
(summed over the entire bay)

46. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
ABUNDANCE IS PROPORTIONAL TO, HENCE MEASURED BY, THE ANNUAL COMMERCIAL HARVEST
ABUNDANCE IS QUANTIFIED ENTIRELY BY 6 BIMONTHLY FLOWS, TOTALLED OVER THE ENTIRE BAY
ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)

47.  the relationship can be extracted by linear regression
 harvest is completely determined by the levels of inflow for a given year (apart from perhaps lagging harvest behind inflow based upon the grow-out time of the species): there is no memory
 there is no substantial effect of recruitment or dynamics of the Gulf stock
 recreational harvest is irrelevant

48. HARVEST REGRESSIONS FOR SAN ANTONIO BAY
H = annual commercial landings, thousands of pounds
Qab = total bimonthly inflow, ac-ft, for sequential months a and b
Crab: H = – ln(QJF) ln (QJA) – ln(QSO)
Oyster: H = ln(QMA) – ln(QMJ) ln(QJA) – ln(QSO)   
R.drum: H = QMJ QJA QND
B.drum: H = QJF QMA QND
Trout: ln(H) = – ln(QMA) ln(QMJ) – *ln(QND)
B. shr: ln(H)= ln(QJA) – ln(QSO)
W. shr: H = ln(QJF) ln(QMJ) – ln(QJA) – *ln(QND)

49. HARVEST REGRESSIONS FOR GALVESTON BAY
H = annual commercial landings, thousands of pounds
Qab = total bimonthly inflow, ac-ft, for sequential months a and b
Crab: H = QJF QMA QMJ QSO QND
Oyster: H = QJF QMJ QJA
Brown
shrimp: H = QJF QJA QSO QND
White
shrimp: H = QJF QMA QJA QND
Flounder: H = QJF QJA QND
Red
drum: ln H = E-4 QMJ E-3 QJA E-4 QSO
Black
drum: H = QJF QJA QSO QND
Seatrout: ln H = ln QJF ln QND

50. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
ABUNDANCE IS PROPORTIONAL TO, HENCE MEASURED BY, THE ANNUAL COMMERCIAL HARVEST
ABUNDANCE IS QUANTIFIED ENTIRELY BY 6 BIMONTHLY FLOWS, TOTALLED OVER THE ENTIRE BAY
ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)
OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH

51. TxEMP MinQ and MaxH Solutions

52. OPTIMAL INFLOWS FOR GALVESTON BAY

54. Mid-Galveston Bay salinity versus Trinity River flow

55. LOWER NUECES BAY

56. SN = salinity in ppt for month N
Regressions of salinity versus monthly inflows for Galveston Bay regions
SN = salinity in ppt for month N
QM = monthly combined inflow in ac-ft for month M
Trinity Bay SN = * log(QN-1) * log(QN-2)
Red Bluff SN = * log(QN-1) * log(QN-2)
Dollar Point SN = * log(QN-1) * log(QN-2)

57. SALINITY VIABILITY LIMITS (ppt) FOR GALVESTON BAY

58. Sabine Lake

59. HERE BEGINS CRITICISM

60. Disaggregated relative contributions
of species and bimonthly flow to total computed harvest
Galveston Bay MaxH flows
const QJF QMA QMJ QJA QSO QND ratio to
total
harvest
Flow (MaxH)  
Blue crab
Oyster
Red drum
Black drum
Spotted seatrout
Brown shrimp
White shrimp
Flounder  
TOTAL

61. Galveston Bay

62. Galveston Bay

63. San Antonio Bay oyster harvest

64. Brown shrimp regression equations
variables:
const JF MA MJ JA SO ND
Brown shrimp regression equations
Galveston Bay H = QJF QJA QSO QND
San Antonio Bay log H = log QJA log QSO
Corpus Christi Bay log H = log QMA log QSO
Black drum regression equations
Galveston Bay H = log QJF log QJA log QSO log QND
San Antonio Bay H = QJF QMA QND
Corpus Christi Bay H = log QJA log QND

65. Statistical data for Corpus Christi Bay regressions
Species Data points R2 S.E
used deleted
Black drum
Flounder
Blue crab
Red drum
Spotted seatrout
Brown shrimp
White shrimp

66. HOW WELL DOES A BAY-TOTAL INFLOW DEPICT THE BIOLOGICAL RESPONSE?

68. HOW ACCURATELY DO TWO-MONTH BINS DEPICT THE TIME-VARIATION OF INFLOW TO A TEXAS BAY?

69. Spring freshet on the Guadalupe at Victoria

70. Fall freshet on the Trinity at Romayor

71. HOW SENSITIVE IS THE OPTIMIZATION SOLUTION, ANYWAY?

72. Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Constraints:
Monthly inflow: >lower decile (10th percentile)
<historical monthly median
Bimonthly inflows:>specified values (>sum of lower decile values)
Salinity: bounded by “consensus” viability limits
Min Q Specification
Objective goal: Minimal total annual inflows
Harvest: >80% of historical mean for each species

76. DOES NATURE EXHIBIT AN OPTIMUM CONSISTENT WITH THE MODEL PREDICTION?

77. 1.79
0.45
0.47
0.53
0.45

78. .27
.07
.05
.02
.03
.05
.05

79. Galveston Bay

80. San Antonio Bay

81. DOES AN OPTIMAL INFLOW OCCUR IN NATURE?

82. San Antonio Bay monthly flows within 10% of maxH

83. San Antonio Bay monthly flows within 10% of maxH (continued)

84. San Antonio Bay monthly flows within 20% of maxH

85. San Antonio Bay monthly flows within 20% of maxH

86. FUNDAMENTAL ASSUMPTIONS OF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
ABUNDANCE IS PROPORTIONAL TO, HENCE MEASURED BY, THE ANNUAL COMMERCIAL HARVEST
ABUNDANCE IS QUANTIFIED ENTIRELY BY 6 BIMONTHLY FLOWS, TOTALLED OVER THE ENTIRE BAY
ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)
sufficient
OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH

87. CONCLUDING CONCERNS

88. Should more species, or other ecological variables, be addressed?
Should other factors, in addition to inflows, be considered in the prediction problem?
Are the analytical methods sufficiently sophisticated for the complexity of the problem?

89. Is this an optimization problem
Is this an optimization problem? Are optimal average conditions even relevant?
Is it necessary to take account of year-to-year variation in estuary conditions? I.e., does a Texas bay have “memory”?