Martin Rule Curve StudyMartin Rule Curve Study

Ashley McVicar, APCAshley McVicar, APC

Maurice James, Water Resources Maurice James, Water Resources Consulting LLC Consulting LLC

Martin Rule Curve StudyMartin Rule Curve Study

PurposePurpose Preliminary modeling study to determine the Preliminary modeling study to determine the

feasibility of a higher winter pool at Martin in feasibility of a higher winter pool at Martin in accordance with MIG 3 Project Operations accordance with MIG 3 Project Operations Study Plan.Study Plan.

Martin Rule Curve StudyMartin Rule Curve Study

Design Flood Study ApproachDesign Flood Study Approach Determine historical flood event to model for Determine historical flood event to model for

the 100 year design flood the 100 year design flood Replicate operations for the actual flood event Replicate operations for the actual flood event

in an operation spreadsheetin an operation spreadsheet Evaluate a higher winter pool vs. baseline of Evaluate a higher winter pool vs. baseline of

elevation 480’elevation 480’ Compare ResultsCompare Results

““100 Year Flood”100 Year Flood” Has a specific definitionHas a specific definition

US Dept of Interior Bulletin 17BUS Dept of Interior Bulletin 17B

Applied by Regulating Agencies (FEMA, Applied by Regulating Agencies (FEMA, COE, FERC, the States, etc.)COE, FERC, the States, etc.)

Frequency Analysis of Maximum Annual Frequency Analysis of Maximum Annual Flood Events.Flood Events.

1% chance of occurrence in each year.1% chance of occurrence in each year. Generally concerned with peak flowGenerally concerned with peak flow For Reservoirs – volume also criticalFor Reservoirs – volume also critical

How is this Analysis Done?How is this Analysis Done?

Select Maximum Flood Event for each Select Maximum Flood Event for each year.year. Prefer 30+ year record.Prefer 30+ year record.

Apply a specific frequency analysis to Apply a specific frequency analysis to data. data. COE Frequency Analysis programCOE Frequency Analysis program Project to 1% probability of exceedence.Project to 1% probability of exceedence.

Monthly AnalysisMonthly Analysis

Not an established procedure.Not an established procedure. Referred to as a “Partial Duration”Referred to as a “Partial Duration”

Only considering part of the record.Only considering part of the record. Maximum event in month for the period Maximum event in month for the period

of record.of record. Annual peak procedures may not apply.Annual peak procedures may not apply. Will still have a probability of exceedence Will still have a probability of exceedence

but not necessarily 1%.but not necessarily 1%.

Horseshoebend Annual Peaks

0%

5%

10%

15%

20%

25%

30%

35%

1 2 3 4 5 6 7 8 9 10 11 12

Month

Perc

en

t

19 Years of Record

Approximate Rule Curve

EL 480 ft.

EL 490 ft.

74%

Probability

0.9999 0.9990 0.9900 0.9000 0.5000 0.1000 0.0100 0.0010 0.0001

Flow

(cf

s)

100.0

1000.0

10000.0

100000.0

Exceedance Probability for Martin DEC Freq Analysis

DEC-MON Observed Events (Weibull plotting positions)

Computed Curve

Expected Probability Curve

5 Percent Confidence Limit

95 Percent Confidence Limit

What does all this say?What does all this say?

There is a chance that the 100 year flood There is a chance that the 100 year flood could occur in any month of the year.could occur in any month of the year.

The greatest chance would be during the The greatest chance would be during the months of Dec. through April.months of Dec. through April.

Not necessary for the record to have an Not necessary for the record to have an event near or greater than the 1% event.event near or greater than the 1% event.

Martin Rule Curve StudyMartin Rule Curve Study

APC Flood Frequency AnalysisAPC Flood Frequency Analysis Model developed by COE – Hydrologic Model developed by COE – Hydrologic

Engineering Center in Davis, CAEngineering Center in Davis, CA Utilizes the COE 1939-2001 unimpaired flow Utilizes the COE 1939-2001 unimpaired flow

database created as part of the ACT database created as part of the ACT Comprehensive StudyComprehensive Study

Submitted to the COE by APC in November Submitted to the COE by APC in November 20052005

Martin Rule Curve StudyMartin Rule Curve Study

Martin flowMartin flow 100 yr flow unregulated = 130,000 cfs-days100 yr flow unregulated = 130,000 cfs-days March 1990 flow unregulated = 125,019 cfs-March 1990 flow unregulated = 125,019 cfs-

days (96% of 100 year flood)days (96% of 100 year flood) March 1990 inflow regulated used in Martin March 1990 inflow regulated used in Martin

Rule Curve evaluation (with Harris and Martin Rule Curve evaluation (with Harris and Martin in place) = 92,307 cfs-days (71% of 100 year in place) = 92,307 cfs-days (71% of 100 year unregulated flood)unregulated flood)

Basin Wide RainfallBasin Wide Rainfall

Current Martin Flood Control Current Martin Flood Control Guidelines Pre-Turbine UpgradesGuidelines Pre-Turbine Upgrades

Martin Rule Curve Study Martin Rule Curve Study Post Turbine UpgradesPost Turbine Upgrades

General AssumptionsGeneral Assumptions Martin Turbine Capacity = 16500 (based on Martin Turbine Capacity = 16500 (based on

upgrades completed in 2004)upgrades completed in 2004) Yates Turbine Capacity = 12400Yates Turbine Capacity = 12400 Thurlow Turbine Capacity = 13200Thurlow Turbine Capacity = 13200 20 spillway gates 20 spillway gates Ability to open 2 spillway gates an hour Ability to open 2 spillway gates an hour

Martin Reservoir Model Calibration

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

3/15 3/16 3/17 3/18 3/19 3/20 3/21 3/22 3/23 3/24

Date

Dis

char

ge

cfs

483.0

484.0

485.0

486.0

487.0

488.0

489.0

490.0

Ele

vati

on

ft.

(M

arti

n D

atu

m)

Model Discharge

Actual Discharge

Inflow

Model Elevation

Actual Elevation

Martin Rule Curve StudyMartin Rule Curve Study

Design Flood EvaluationDesign Flood Evaluation Operational criteria set forth in model Operational criteria set forth in model

accurately replicated historical conditionsaccurately replicated historical conditions

Martin Rule Curve StudyMartin Rule Curve Study

Evaluation of Winter Pool of 480’ vs. 483’Evaluation of Winter Pool of 480’ vs. 483’ Used current operational criteria set forth by Used current operational criteria set forth by

March 1990 flood historical operations and March 1990 flood historical operations and began pool at both 480’ and 483’began pool at both 480’ and 483’

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Martin Reservoir 480 vs. 483 Model Simulation

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

15 16 17 18 19 20 21 22 23 24

Date

Dis

char

ge

cfs

478

480

482

484

486

488

490

492

Ele

vati

on

ft.

(M

arti

n D

atu

m)

480 Discharge

483 Discharge

Inflow

480 Elevation

483 Elevation

Martin Rule Curve StudyMartin Rule Curve Study

Elevation 480’ vs 483’ ResultsElevation 480’ vs 483’ Results Martin pool kept below top of easement Martin pool kept below top of easement

elevation 490 for both elevation 490 for both Beginning winter pool elevation of 483’ results Beginning winter pool elevation of 483’ results

in earlier releases as well as approximately in earlier releases as well as approximately 25-30k higher discharge during the peak25-30k higher discharge during the peak

Resulting outflows passed downstream Resulting outflows passed downstream with HEC-RAS model with HEC-RAS model

Tallapoosa Profile

150

155

160

165

170

175

180

185

190

195

200

205

210

215

220

0 5 10 15 20 25 30 35 40 45 50 55

Tallapoosa River Mile

Max

imu

m E

leva

tio

n f

t. m

sl Initial Pool-480

Initial Pool-483Montgomery Water

Works gage

Milestead gage

Tallassee gage

Alabama River Thurlow Dam

Martin Rule Curve StudyMartin Rule Curve Study

ResultsResults Elevations downstream result in a 1’ – 3’ Elevations downstream result in a 1’ – 3’

higher elevation downstream to Alabama higher elevation downstream to Alabama River.River.

COE uses FEMA’s requirement of “no COE uses FEMA’s requirement of “no increase of peak elevation downstream”increase of peak elevation downstream”

FERC defers to the COE for flood analysisFERC defers to the COE for flood analysis FERC would require a full analysis of flood, FERC would require a full analysis of flood,

environmental and recreational impacts of environmental and recreational impacts of proposed vs. current operation proposed vs. current operation

Martin Rule Curve StudyMartin Rule Curve Study

Further Study during Relicensing RequiredFurther Study during Relicensing Required MIG 3 proposals evaluatedMIG 3 proposals evaluated Look at different winter pool elevation and/or shape of Look at different winter pool elevation and/or shape of

Rule Curve Rule Curve Look at different operational plansLook at different operational plans Further evaluate downstream flood & environmental Further evaluate downstream flood & environmental

impacts and present these effects and associated impacts and present these effects and associated mitigation measures to FERCmitigation measures to FERC

FERC will then evaluate and balance all interestsFERC will then evaluate and balance all interests