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Presentation to Nueces BBASC Sam Vaugh, PE
Cory Shockley, PE – HDR Engineering May 23, 2012
1
April 23rd Discussion Instream Flow
Planned Water Supply Project Evaluations Sabinal Recharge Dam
Standard and Strategy Evaluation Nueces River @ Laguna Nueces River @ Cotulla
Yield vs. e-flow regime Recommendation
Develop Modified BBEST W Ecological and sediment analysis
Modified BBEST A Modified BBEST W
2
April 23rd Discussion Nueces Bay & Delta
Planned Water Supply Project Evaluations Lake Corpus Christi Off Channel Reservoir
B&E Scenario Evaluation Yield Average Bay Inflow
Path Forward Evaluate scenarios to recommend attainment frequencies of
meeting the BBEST targets that allow for the balance for human needs.
3
Discussion Instream Flow
HDR Summary of April 23rd Analysis Presentation of Modified BBEST W
BBEST Presentation of Aquatic Habitat Analysis
TWDB Presentation of Sediment Analysis
BBASC vote to adopt an e-flow regime
4
Discussion Nueces Bay & Delta
B&E Scenario Evaluation BBEST Recommendation Agreed Order Safe Yield No Pass-Thru’s OCR Order Safe Yield
Yield Attainment Frequencies Salinity
BBASC vote to adopt an e-flow regime
5
Focal Sites for BBASC Instream Flow Standard Recommendations
6
Defined – Modified BBEST Overbank Exemption Pulse Exemption Rule
diversion rate < 20% of the flow pulse trigger 20% rule not applicable to on-channel reservoirs
Single Tier of Base Flows with 50% Rule Diversions may not exceed 50% of the difference
between the base flow and the subsistence flow. Evaluated Wet and Average Base Flow Tiers
7
Sabinal River near Sabinal
8
9
36% 36%
81%
36%
81% 81%0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
No E-FlowRestrictions
Lyons CCEFN Modified BBEST W
Modified BBEST A
Full BBEST
Aver
age
Annu
al En
hanc
ed R
echa
rge (
acft
/yr)
Sabinal River at Sabinal Recharge Reservoir - Enhanced Recharge
Long Term Avg (1934-1996)
Drought Avg (1947-1956)
10
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Sabinal River at Sabinal Recharge Reservoir - Flow Frequency Curve
Historical
Full BBEST
Modified BBEST A
Modified BBEST W
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
Sabinal Recharge Dam Preliminary Conclusions
The impoundment of high flow pulses by the Sabinal Dam provides the greatest opportunity for recharge enhancement.
Variations in base flow criteria have negligible effects on enhanced recharge.
Downstream Impacts System yield = -1,900 to -2,300 acft/yr Average Annual Bay Inflow = -850 acft/yr
11
Standard & Strategy Evaluation Laguna ROTR with OCR Cotulla Reservoir Cotulla ROTR with OCR Evaluate:
No Recommendation BBEST Recommendation Modifications to BBEST Recommendation
Results: Yield Streamflows
12
Nueces River @ Laguna - BBEST
13
Overbank Events
Subsistence Flows (cfs)
Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
Pulse volumes are in units of acre-feet and durations are in days.Period of Record used : 1/1/1924 to 12/31/2009.
Qp: 15,600 cfs with Average Frequency 1 per 5 yearsRegressed Volume is 124,000
Duration Bound is 107
High Flow Pulses
Qp: 4,750 cfs with Average Frequency 1 per 2 yearsRegressed Volume is 38,600
Duration Bound is 64
Winter Spring Summer Fall
44 32 41
14 18 16 14
Qp: 2,220 cfs with Average Frequency 1 per yearRegressed Volume is 18,400
Duration Bound is 46
Base Flows (cfs) 48 65
Flow Levels
High (75th %ile)
Medium (50th %ile)
Low (25th %ile)
Subsistence
5165
Qp: 590 cfs with Average Frequency 2 per yearVolume Bound is 11,300Duration Bound is 26
Qp: 48 cfs with Average Frequency 1 per season
Volume Bound is 1,000Duration Bound is 7
Qp: 390 cfs with Average Frequency 1 per seasonVolume Bound is 6,070Duration Bound is 17
Qp: 170 cfs with Average Frequency 1 per seasonVolume Bound is 3,100Duration Bound is 14
Qp: 50 cfs with Average Frequency 1
per seasonVolume Bound is 800Duration Bound is 5
Qp: 99 cfs with Average Frequency 2 per seasonVolume Bound is 1,560Duration Bound is 9
76 9292
14
54% 58% 61% 62%69%
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
No E-Flow Criteria Lyons CCEFN Modified BBEST A Modified BBEST W
Full BBEST
Firm
Yie
ld (a
cft/
yr)
Nueces River at Laguna OCR - Firm Yield
15
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Nueces River at Laguna OCR - Annual Flow Frequency Curve
Historical
Full BBEST
Modified BBEST W
Modified BBEST A
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
16
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Nueces River at Laguna OCR - Annual Flow Frequency Curve
Historical
Full BBEST
Modified BBEST W
Modified BBEST A
CCEFN
Lyons
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
Nueces River @ Cotulla - BBEST
17
Subsistence Flows (cfs)
Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Pulse volumes are in units of acre-feet and durations are in days.Period of Record used : 1/1/1927 to 12/31/2009.
Overbank Events
High Flow Pulses
Base Flows (cfs)
38
Qp: 4,460 cfs with Average Frequency 1 per yearRegressed Volume is 41,100
Duration Bound is 34
Qp: 1,560 cfs with Average Frequency 2 per yearVolume Bound is 24,200Duration Bound is 28
Qp: 96 cfs with Average Frequency 1 per seasonVolume Bound is 1,570Duration Bound is 20
Qp: 1,180 cfs with Average Frequency 1 per seasonVolume Bound is 17,200Duration Bound is 24
Qp: 100 cfs with Average Frequency 1
per seasonVolume Bound is
1,030Duration Bound is 16
Qp: 640 cfs with Average Frequency 1
per seasonVolume Bound is
8,610Duration Bound is 26
Qp: 15,100 cfs with Average Frequency 1 per 5 yearsRegressed Volume is 151,000
Duration Bound is 42
Qp: 8,410 cfs with Average Frequency 1 per 2 yearsRegressed Volume is 80,700
Duration Bound is 38
Qp: 8 cfs with Average Frequency 2 per seasonVolume Bound is 100Duration Bound is 13
Qp: 190 cfs with Average Frequency 2 per seasonVolume Bound is 2,370Duration Bound is 17
Qp: 35 cfs with Average Frequency 2
per seasonVolume Bound is 360Duration Bound is 14
Qp: 15 cfs with Average Frequency 3 per seasonVolume Bound is 150Duration Bound is 11
Winter Spring Summer Fall
10 7 1531
1
1
426
Flow Levels
High (75th %ile)
Medium (50th %ile)
Low (25th %ile)
Subsistence
18
7% 9%15%
58%
18%
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
No E-Flow Criteria Lyons CCEFN Modified BBEST A Modified BBEST W Full BBEST
Firm
Yie
ld (a
cft/
yr)
Cotulla Reservoir - Firm Yield
19
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Cotulla Reservoir - Annual Flow Frequency Curve
Historical
Full BBEST
Modified BBEST W
Modified BBEST A
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
20
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Cotulla Reservoir - Annual Flow Frequency Curve
Historical
Modified BBEST W
Full BBEST
Modified BBEST A
CCEFN
Lyons
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
Nueces River @ Cotulla - BBEST
21
Subsistence Flows (cfs)
Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Pulse volumes are in units of acre-feet and durations are in days.Period of Record used : 1/1/1927 to 12/31/2009.
Overbank Events
High Flow Pulses
Base Flows (cfs)
38
Qp: 4,460 cfs with Average Frequency 1 per yearRegressed Volume is 41,100
Duration Bound is 34
Qp: 1,560 cfs with Average Frequency 2 per yearVolume Bound is 24,200Duration Bound is 28
Qp: 96 cfs with Average Frequency 1 per seasonVolume Bound is 1,570Duration Bound is 20
Qp: 1,180 cfs with Average Frequency 1 per seasonVolume Bound is 17,200Duration Bound is 24
Qp: 100 cfs with Average Frequency 1
per seasonVolume Bound is
1,030Duration Bound is 16
Qp: 640 cfs with Average Frequency 1
per seasonVolume Bound is
8,610Duration Bound is 26
Qp: 15,100 cfs with Average Frequency 1 per 5 yearsRegressed Volume is 151,000
Duration Bound is 42
Qp: 8,410 cfs with Average Frequency 1 per 2 yearsRegressed Volume is 80,700
Duration Bound is 38
Qp: 8 cfs with Average Frequency 2 per seasonVolume Bound is 100Duration Bound is 13
Qp: 190 cfs with Average Frequency 2 per seasonVolume Bound is 2,370Duration Bound is 17
Qp: 35 cfs with Average Frequency 2
per seasonVolume Bound is 360Duration Bound is 14
Qp: 15 cfs with Average Frequency 3 per seasonVolume Bound is 150Duration Bound is 11
Winter Spring Summer Fall
10 7 1531
1
1
426
Flow Levels
High (75th %ile)
Medium (50th %ile)
Low (25th %ile)
Subsistence
22
19% 20% 25% 26%
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
No E-Flow Criteria CCEFN Lyons Modified BBEST A Full BBEST Modified BBEST W
Firm
Yie
ld (a
cft/
yr)
Cotulla Off-Channel Reservoir - Firm Yield
16%
23
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Cotulla Off-Channel Reservoir - Annual Flow Frequency Curve
Historical
Modified BBEST W
Full BBEST
Modified BBEST A
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
24
0
50
100
150
200
250
300
350
400
450
500
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Flow
(cfs
)
Percentage of Time Flows are Equaled or Exceeded
Cotulla Off-Channel Reservoir - Annual Flow Frequency Curve
Historical
Modified BBEST W
Full BBEST
Lyons
CCEFN
Modified BBEST
No E-Flow Criteria
Period of Record: 1/1/1934 to 12/31/1996Period of Record: 1/1/1934 to 12/31/1996
Path Forward Additional Presentations
BBEST - Aquatic Habitat TWDB - Sediment Transport
BBASC Adopt an Instream Environmental Flow Standard Recommendation Modified BBEST
Overbank Exemption Pulse Exemption Rule Base Flow with 50% Rule
Wet Average
25
Nueces Bay and Delta Inflow Regime BBASC Direction
Utilize BBEST Volume Targets Modify Attainment Frequencies for Balance
Four Focused Scenarios BBEST Recommendation Agreed Order – Safe Yield No Pass Thru’s OCR Agreed Order Safe Yield
Results Yield vs. Bay Inflow vs. Salinity
26
Order Compared to BBEST Sys Stor.
%
Jan (acft)
Feb (acft)
Mar (acft)
Apr (acft)
May (acft)
Jun (acft)
Jul (acft)
Aug (acft)
Sep (acft)
Oct (acft)
Nov (acft)
Dec (acft)
Ann. (acft)
>70 2,500 2,500 3,500 3,500 25,500 25,500 6,500 6,500 28,500 20,000 9,000 4,500 138,000
70-40 2,500 2,500 3,500 3,500 23,500 23,000 4,500 5,000 11,500 9,000 4,000 4,500 97,000
40-30 1,200 1,200 1,200 1,200 1,200 1,200 1,200 1,200 1,200 1,200 1,200 1,200 14,400
>30 0 0 0 0 0 0 0 0 0 0 0 0 0
2001 TCEQ Agreed Order
Condition (Target Salinity)
Nueces Bay Freshwater Inflow Regime (Attainment) Recommendations
One overbanking event per year of 39,000 acft; maximum discharge of 3,600 cfs Annual Total (acft)
Attainment
High (10) 125,000 acft (20%) 250,000 acft (25%) 375,000 (20%) 750,000 25%
Base (18) 22,000 acft (60%) 88,000 acft (60%) 56,000 (75%) 166,000 80%
Subsistence (34) 5,000 acft (95%) 10,000 acft (95%) 15,000 acft (95%) 30,000 95%
Winter = Nov - Feb Spring = Mar - Jun Summer/Fall = Jul - Oct
2011 BBEST Recommendation
27
BBEST Recommendation for B&E Condition
(Target Salinity)
Nueces Bay Freshwater Inflow Regime (Attainment) Recommendations
One overbanking event per year of 39,000 acft; maximum discharge of 3,600 cfs
Annual Total (acft)
High (10) 125,000 acft (20%)
250,000 acft (25%)
375,000 (20%)
750,000 (25%)
Base (18) 22,000 acft (60%)
88,000 acft (60%)
56,000 (75%)
166,000 (80%)
Sub. (34) 5,000 acft (95%)
10,000 acft (95%)
15,000 acft (95%)
30,000 (95%)
Winter = Nov - Feb
Spring = Mar - Jun
Summer/Fall = Jul - Oct
28
29
0
50,000
100,000
150,000
200,000
250,000
300,000
Full_BBEST Base_SY No_PT OCR_SY
Acft
/Yr
CCR/LCC/LT System Safe Yield (acft/yr)
SY (75K Min)
30
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
Full_BBEST Base_SY No_PT OCR_SY
Acft
/Yr
CCR/LCC/LT System Safe Yield - Average Annual Bay Inflow - Average Annual B&E Release
SY (75K Min)Avg AQBAYAvg ABEREL
31
0%
5%
10%
15%
20%
25%
30%
W-H Sp-H S-H A-H
BBESTBBEST SimulationBase SY (Order)No Pass ThroughsOCR-SY-Order
32
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
W-B Sp-B S-B A-B
BBEST RecommendationBBEST SimulationBase SY (Order)No Pass ThroughsOCR_SY_Order
33
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
W-S Sp-S S-S A-S
BBEST Recommendation
BBEST Simulation
Base SY (Order)
No Pass Throughs
OCR-SY-Order
34
0
5
10
15
20
25
30
35
40
45
50
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Salin
ty at
SALT
03
Percent of Time
BBEST Scenario SALT03 (ppt)Base Agreed Order SALT03 (ppt)No Pass Thru's SALT03 (ppt)OCR SY SALT03 (ppt)
35
0
5
10
15
20
25
30
60% 65% 70% 75% 80% 85% 90% 95% 100%
Salin
ty at
SALT
03
Percent of Time
BBEST Scenario SALT03 (ppt)Base Agreed Order SALT03 (ppt)No Pass Thru's SALT03 (ppt)OCR SY SALT03 (ppt)
13%
8% 5%
6%
B&E – Attainment Freq – Opt 1 Condition
(Target Salinity)
Nueces Bay Freshwater Inflow Regime (Attainment) Recommendations
Annual Total (acft)
High (10) 125,000 acft (9%)
250,000 acft (10%)
375,000 (12%)
750,000 (11%)
Base (18) 22,000 acft (22%)
88,000 acft (19%)
56,000 (33%)
166,000 (38%)
Sub. (34) 5,000 acft (61%)
10,000 acft (82%)
15,000 acft (71%)
30,000 (90%)
Winter = Nov - Feb
Spring = Mar - Jun
Summer/Fall = Jul - Oct
36
B&E – Attainment Freq – Opt 2 Condition
(Target Salinity)
Nueces Bay Freshwater Inflow Regime (Attainment) Recommendations
Annual Total (acft)
High (10) 125,000 acft (11%)
250,000 acft (11%)
375,000 (12%)
750,000 (16%)
Base (18) 22,000 acft (23%)
88,000 acft (30%)
56,000 (40%)
166,000 (47%)
Sub. (34) 5,000 acft (69%)
10,000 acft (88%)
15,000 acft (74%)
30,000 (95%)
Winter = Nov - Feb
Spring = Mar - Jun
Summer/Fall = Jul - Oct
37
For BBASC Consideration BBASC Adopt an Estuary & Delta Environmental Flow
Standard Recommendation BBEST Seasonal Volume Targets Attainment Frequencies
Option 1 - Agreed Order plus OCR Option 2 - Agreed Order
38
Path Forward / Questions? Report Compilation
39
40
Scenario Results Yield vs. Avg. Annual Bay Inflow
41
Run # Run Description SY (75K Min) Avg AQBAY1 Base_SY 204,449 379,2842 No_PT 235,001 350,8003 Seasonal_order 169,691 410,4544 Spring_target 170,889 415,4915 Summer_Tar 180,960 405,9006 Winter_Tar 213,264 372,5477 3K_All_months 230,089 358,0198 Reduced may June 220,110 364,423
42
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Mon
thly
Bay
Inflo
w (A
cft)
Percent of Time (% - months)
Monthly Bay Inflow - Frequency
Run 1
Run 2
Run 3
Run 4
Run 5
Run 6
Run 7
Run 8
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