the state methodology for determination of freshwater inflow needs of the texas bays
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The State Methodology for determination of freshwater inflow needs of the Texas bays. The State Methodology for determination of freshwater inflow needs of the Texas bays. Overview & Critique. Presentation to:. Science Advisory Committee. George H. Ward - PowerPoint PPT PresentationTRANSCRIPT
The State Methodologyfor determination of freshwater inflow
needs of the Texas bays
The State Methodologyfor determination of freshwater inflow
needs of the Texas bays
George H. Ward
Center for Research in Water ResourcesUniversity of Texas at Austin
Overview & Critique
Presentation to:
Science Advisory Committee
Study Commission on Water for Environmental Flows
18 June 2004
Sabine Lake
Galveston Bay
Matagorda Bay
San Antonio Bay
Aransas-Copano Bays
Corpus Christi Bay
Upper Laguna Madre-Baffin Bay
Lower Laguna Madre
ESTUARY
coastal waterbody
semi-enclosed
free connection to open sea
influx of sea water
freshwater influx
small to intermediate scale
ESTUARIES
transitional systems, between freshwater and marine
hydrography and chemical qualities governed by both terrestrial and marine controls, as well as factors unique to estuary
predominance of these factors depends upon position in estuary: pronounced environmental gradients
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
transitional systems, between freshwater and marine
hydrography and chemical qualities governed by both terrestrial and marine controls, as well as factors unique to estuary
predominance of these factors depends upon position in estuary: pronounced environmental gradients
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
extreme time variability in estuaryextreme time variability in estuary
cross section view(longitudinal-vertical)
plan view(surface horizontal)
ESTUARIES
wide range in habitats spanning the estuarine zone
majority of the larger animals in estuary only temporarily for specific biological purposes
ESTUARIES
wide range in habitats spanning the estuarine zone
majority of the larger animals in estuary only temporarily for specific biological purposes
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
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
Potential freshwater inflow effects on estuary
source of renewal water
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
STATE METHODOLOGY FOR DETERMINING INFLOW
REQUIREMENTS OF THE TEXAS BAYS
An overview & summary
San Antonio Bay
OPTIMAL INFLOWS FOR SAN ANTONIO BAY
OPTIMAL INFLOWS FOR GALVESTON BAY
Max H SpecificationObjective goal: Maximal harvest
Species weights: equal
Min Q Specification
Objective goal: Minimal total annual inflows
Species weights: equal
Max H SpecificationObjective 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
Species weights: equal
Constraints:
Harvest: >80% of historical mean for each speciesMonthly inflow: >lower decile (10th percentile)
<historical monthly medianBimonthly inflows:>specified values (>sum of lower decile values)Salinity: bounded by “consensus” viability limits
FUNDAMENTAL ASSUMPTIONSOF THE STATE METHODOLOGY
ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout
For San Antonio Bay, the 7 key species are:
blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout flounder
For Galveston Bay, the 8 key species are:
blue crab brown shrimp
menhaden white shrimp
red drum croaker
spot speckled trout
For Sabine Lake, the 8 key species are:
FUNDAMENTAL ASSUMPTIONSOF 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
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
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
FUNDAMENTAL ASSUMPTIONSOF 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
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)
6 independent flow variables ( “seasonal” flows):
FUNDAMENTAL ASSUMPTIONSOF 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)
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
HARVEST REGRESSIONS FOR SAN ANTONIO BAYH = annual commercial landings, thousands of poundsQab = total bimonthly inflow, ac-ft, for sequential months a and b
Crab: H = 110.64 – 145.3 ln(QJF) + 332.5 ln (QJA) – 141.4 ln(QSO)
Oyster: H = 3000.7 + 180.4 ln(QMA) – 963.3 ln(QMJ) + 710.0 ln(QJA) – 231.5 ln(QSO)
R.drum: H = 32.786 + 0.0797 QMJ + 0.2750 QJA - 0.2010 QND
B.drum: H = -18.087 + 0.2411 QJF - 0.1734 QMA + 0.0850 QND
Trout: ln(H) = 2.6915 – 0.7185 ln(QMA) + 1.860 ln(QMJ) – 1.086 *ln(QND)
B. shr: ln(H)= 6.5679 + 0.6707 ln(QJA) – 0.7486 ln(QSO)
W. shr: H = 545.59 + 160.9 ln(QJF) + 279.1 ln(QMJ) – 155.1 ln(QJA) – 277.9 *ln(QND)
H = annual commercial landings, thousands of poundsQab = total bimonthly inflow, ac-ft, for sequential months a and b
Crab: H = 751.23 - 0.2756 QJF + 0.8464 QMA - 0.139 QMJ - 0.4747 QSO + 0.6001 QND
Oyster: H = 4169.8 - 0.9397 QJF +0.2838 QMJ - 0.9445 QJA
Brownshrimp: H = 1019.8 - 0.5779 QJF + 0.4192 QJA + 0.4060 QSO + 0.3533 QND
Whiteshrimp: H = 3212 - 0.6905 QJF + 0.2734 QMA - 0.3254 QJA + 0.5046 QND
Flounder: H = -12.122 - 0.0309 QJF + 0.0541 QJA + 0.0494 QND
Red drum: ln H = 3.1548 + 3.92E-4 QMJ - 2.04E-3 QJA + 6.98E-4 QSO
Blackdrum: H = 50.225 - 0.02985 QJF + 0.1040 QJA - 0.0639 QSO + 0.0329 QND
Seatrout: ln H = 8.2764 - 1.8241 ln QJF +1.425 ln QND
HARVEST REGRESSIONS FOR GALVESTON BAY
FUNDAMENTAL ASSUMPTIONSOF 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
OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH
ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)
TxEMP MinQ and MaxH Solutions
OPTIMAL INFLOWS FOR GALVESTON BAY
Mid-Galveston Bay salinity versus Trinity River flow
LOWER NUECES BAY
Regressions of salinity versus monthly inflows for Galveston Bay regions
SN = salinity in ppt for month NQM = monthly combined inflow in ac-ft for month M
Trinity Bay SN = 49.109 - 3.221 * log(QN-1) - 3.039 * log(QN-2)
Red Bluff SN = 42.438 - 3.567 * log(QN-1) - 1.179 * log(QN-2)
Dollar Point SN = 48.803 - 4.316 * log(QN-1) - 0.757 * log(QN-2)
SALINITY VIABILITY LIMITS (ppt) FOR GALVESTON BAY
Sabine Lake
HERE BEGINS CRITICISM
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
totalharvest
Flow (MaxH) 0.0586 0.2464 0.4052 0.0674 0.0348 0.1876
Blue crab 0.0643 -0.0072 0.0932 -0.0333 -0.0074 0.0503 0.160
Oyster 0.3571 -0.0246 0.0514 -0.0284 0.355
Red drum 0.0020 0.0018 -0.0016 0.0003 0.003
Black drum 0.0043 -0.0008 0.0031 -0.0010 0.0028 0.008
Spotted seatrout 0.029
Brown shrimp 0.0873 -0.0151 0.0126 0.0063 0.0296 0.121
White shrimp 0.2751 -0.0181 0.0301 -0.0098 0.0423 0.320
Flounder -0.0010 -0.0008 0.0016 0.0041 0.004
TOTAL 0.7891 -0.0666 0.1233 0.0199 -0.0224 -0.0018 0.1290 1.000
Galveston Bay
Galveston Bay
San Antonio Bay oyster harvest
Galveston Bay H = 1020 -0.58 QJF + 0.42 QJA + 0.41 QSO +0.35 QND
San Antonio Bay log H = 6.57 + 0.67 log QJA -0.75 log QSO
Corpus Christi Bay log H = 7.94 +0.30 log QMA -0.52 log QSO
Galveston Bay H = 50.22 -0.03 log QJF +0.10 log QJA -0.06 log QSO +0.03 log QND
San Antonio Bay H = -18.09 +0.24 QJF -0.17 QMA +0.09 QND
Corpus Christi Bay H = -47.74 +44.5 +25.6 log QJA +15.6 log QND QJF
Brown shrimp regression equations
Black drum regression equations
variables: const JF MA MJ JA SO ND
Black drum 31 2 0.79 57
Flounder 23 10 0.52 0.62
Blue crab 27 6 0.37 0.97
Red drum 20 0 0.85 0.58
Spotted seatrout 20 0 0.93 0.29
Brown shrimp 22 14 0.62 0.26
White shrimp 16 20 0.64 0.26
Species Data points R2 S.E
used deleted
Statistical data for Corpus Christi Bay regressions
HOW WELL DOES A BAY-TOTAL INFLOW DEPICT THE BIOLOGICAL RESPONSE?
HOW ACCURATELY DO TWO-MONTH BINS DEPICT THE TIME-VARIATION OF INFLOW
TO A TEXAS BAY?
Spring freshet on the Guadalupe at Victoria
Fall freshet on the Trinity at Romayor
HOW SENSITIVE IS THE OPTIMIZATION SOLUTION, ANYWAY?
Max H SpecificationObjective 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
Species weights: equal
Constraints:
Harvest: >80% of historical mean for each speciesMonthly inflow: >lower decile (10th percentile)
<historical monthly medianBimonthly inflows:>specified values (>sum of lower decile values)Salinity: bounded by “consensus” viability limits
DOES NATURE EXHIBIT AN OPTIMUM CONSISTENT WITH THE MODEL
PREDICTION?
0.45 0.450.47 0.531.79
.27 .07 .05 .02 .03 .05 .05
Galveston Bay
San Antonio Bay
DOES AN OPTIMAL INFLOWOCCUR IN NATURE?
MaxH 111.2 124.2 52.42 52.42 222.6 162.7 88.61 88.33 52.42 52.42 73.83 66.2 within 10% Month year J F M A M J J A S O N D
1941 1942 1943 170.4 1944 121.1 92.0 1945 52.2 1946 1947 89.0 69.2 1948 52.5 1949 221.2 50.3 72.6 1950 1951 1952 53.2 1953 50.8 1954 1955 1956 1957 1958 1959 109.7 1960 114.3 1961 1962 159.0 1963 53.3 1964 52.1 90.0 1965 53.8 1966 74.6 65.0 1967 1968 1969 166.9 1970
San Antonio Bay monthly flows within 10% of maxH
MaxH 111.2 124.2 52.42 52.42 222.6 162.7 88.61 88.33 52.42 52.42 73.83 66.2 Month year J F M A M J J A S O N D
1971 1972 1973 1974 1975 1976 111.0 1977 1978 167.0 1979 1980 76.0 1981 1982 111.2 1983 1984 1985 1986 124.2 1987 1988 53.6 1989 1990 1991 214.4 164.4 1992 1993 1994 1995 1996 1997 1998 1999 121.8
San Antonio Bay monthly flows within 10% of maxH (continued)
MaxH 111.2 124.2 52.42 52.42 222.6 162.7 88.61 88.33 52.42 52.42 73.83 66.2 within 20% Month year J F M A M J J A S O N D
1941 1942 135.4 1943 170.4 56.7 79.0 1944 121.1 92.0 1945 150.1 52.2 1946 103.3 1947 89.0 55.9 80.3 69.2 1948 52.5 49.5 1949 221.2 50.3 72.6 1950 56.3 1951 1952 203.9 53.2 1953 119.2 50.8 70.5 1954 55.3 1955 1956 1957 1958 1959 109.7 1960 114.3 1961 1962 159.0 1963 53.3 56.6 1964 52.1 90.0 1965 83.5 53.8 1966 74.6 65.0 1967 1968 1969 166.9 1970
San Antonio Bay monthly flows within 20% of maxH
MaxH 111.2 124.2 52.42 52.42 222.6 162.7 88.61 88.33 52.42 52.42 73.83 66.2 within 20% Month year J F M A M J J A S O N D
1971 48.0 1972 1973 134.3 202.2 1974 153.0 1975 1976 111.0 1977 95.9 1978 114.2 167.0 1979 80.8 1980 76.0 1981 1982 111.2 70.7 1983 1984 1985 116.3 1986 124.2 1987 240.2 1988 53.6 1989 1990 47.2 1991 214.4 164.4 1992 1993 1994 1995 82.1 66.5 1996 1997 1998 122.3 1999 121.8
San Antonio Bay monthly flows within 20% of maxH
FUNDAMENTAL ASSUMPTIONSOF 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
OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH
ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)
sufficient
CONCLUDING CONCERNS
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?
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”?