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
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 George H. Ward
Center for Research in Water Resources University of Texas at Austin Overview & Critique Presentation to: Science Advisory Committee Study Commission on Water for Environmental Flows 18 June 2004
Slide3 : Sabine Lake Galveston Bay Matagorda Bay San Antonio Bay Aransas-Copano Bays Corpus Christi Bay Upper Laguna Madre- Baffin Bay Lower Laguna Madre
Slide4 : ESTUARY coastal waterbody semi-enclosed free connection to open sea influx of sea water freshwater influx small to intermediate scale
ESTUARIES : 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 estuary extreme time variability in estuary
Slide9 : cross section view (longitudinal-vertical) plan view (surface horizontal)
ESTUARIES : ESTUARIES wide range in habitats spanning the estuarine zone majority of the larger animals in estuary only temporarily for specific biological purposes
ESTUARIES : 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
Slide19 : 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
Slide27 : STATE METHODOLOGY FOR DETERMINING INFLOW REQUIREMENTS OF THE TEXAS BAYS An overview & summary
Slide28 : San Antonio Bay
Slide30 : OPTIMAL INFLOWS FOR SAN ANTONIO BAY
Slide31 : OPTIMAL INFLOWS FOR GALVESTON BAY
Slide34 : Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Min Q Specification
Objective goal: Minimal total annual inflows
Species weights: equal
Slide36 : Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Constraints:
Monthly inflow: >lower decile (10th percentile)
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 species
Monthly inflow: >lower decile (10th percentile)
specified values (>sum of lower decile values)
Salinity: bounded by “consensus” viability limits
Slide37 : FUNDAMENTAL ASSUMPTIONS
OF THE STATE METHODOLOGY ECOLOGICAL HEALTH IS MEASURED BY THE ABUNDANCE OF 6-10 KEY SPECIES
Slide38 : blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout For San Antonio Bay, the 7 key species are:
Slide39 : blue crab brown shrimp
oyster white shrimp
red drum black drum
spotted seatrout flounder For Galveston Bay, the 8 key species are:
Slide40 : blue crab brown shrimp
menhaden white shrimp
red drum croaker
spot speckled trout For Sabine Lake, the 8 key species are:
Slide41 : 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
Slide42 : 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
Slide43 : 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
Slide44 : 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
Slide45 : 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):
Slide46 : 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)
Slide47 : 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
Slide48 : 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 = 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)
Slide49 : H = annual commercial landings, thousands of pounds
Qab = 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
Brown
shrimp: H = 1019.8 - 0.5779 QJF + 0.4192 QJA + 0.4060 QSO + 0.3533 QND
White
shrimp: 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
Black
drum: 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
Slide50 : 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 OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed)
Slide51 : TxEMP MinQ and MaxH Solutions
Slide52 : OPTIMAL INFLOWS FOR GALVESTON BAY
Slide54 : Mid-Galveston Bay salinity versus Trinity River flow
Slide55 : LOWER NUECES BAY
Slide56 : 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 = 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)
Slide57 : SALINITY VIABILITY LIMITS (ppt) FOR GALVESTON BAY
Slide58 : Sabine Lake
Slide59 : HERE BEGINS CRITICISM
Slide60 : 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) 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
Slide61 : Galveston Bay
Slide62 : Galveston Bay
Slide63 : San Antonio Bay oyster harvest
Slide64 : 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 Brown shrimp regression equations Black drum regression equations variables: const JF MA MJ JA SO ND
Slide65 : 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
Slide66 : HOW WELL DOES A BAY-TOTAL INFLOW DEPICT THE BIOLOGICAL RESPONSE?
Slide68 : HOW ACCURATELY DO TWO-MONTH BINS DEPICT THE TIME-VARIATION OF INFLOW TO A TEXAS BAY?
Slide69 : Spring freshet on the Guadalupe at Victoria
Slide70 : Fall freshet on the Trinity at Romayor
Slide71 : HOW SENSITIVE IS THE OPTIMIZATION SOLUTION, ANYWAY?
Slide72 : Max H Specification
Objective goal: Maximal harvest
Species weights: equal
Constraints:
Monthly inflow: >lower decile (10th percentile)
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 species
Monthly inflow: >lower decile (10th percentile)
specified values (>sum of lower decile values)
Salinity: bounded by “consensus” viability limits
Slide76 : DOES NATURE EXHIBIT AN OPTIMUM CONSISTENT WITH THE MODEL PREDICTION?
Slide77 : 0.45 0.45 0.47 0.53 1.79
Slide78 : .27 .07 .05 .02 .03 .05 .05
Slide79 : Galveston Bay
Slide80 : San Antonio Bay
Slide81 : DOES AN OPTIMAL INFLOW OCCUR IN NATURE?
Slide82 : San Antonio Bay monthly flows within 10% of maxH
Slide83 : San Antonio Bay monthly flows within 10% of maxH (continued)
Slide84 : San Antonio Bay monthly flows within 20% of maxH
Slide85 : San Antonio Bay monthly flows within 20% of maxH
Slide86 : 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 OPTIMUM FLOWS ARE NECESSARY FOR MAINTENANCE OF ECOLOGICAL HEALTH ABUNDANCE VARIES IN PROPORTION TO THE BIMONTHLY BAY-TOTAL FLOWS (perhaps log transformed) sufficient
Slide87 : CONCLUDING CONCERNS
Slide88 : 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?
Slide89 : 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”?