Water Quality Modeling used to Inform Operational Decisions for the NYC Water Supply:

Water Quality Modeling used to Inform Operational Decisions for the

NYC Water Supply: A Ten Year Retrospective

Mark S. Zion, Donald C. Pierson,Elliot M. Schneiderman and Adao H. Matonse

New York City Department of Environmental Protection

NYC Watershed/Tifft Science and Technical SymposiumWest Point, New York

September 18-19, 2013

2

Introduction

• Over the last decade, DEP has developed and applied an extensive suite of water quality and water system models which are used to analyze turbidity transport in the Catskill System.

• Elevated turbidity can be an issue for the Catskill System of the NYC water supply during and after periods of high streamflow.

• Informed operations during event periods can help to mitigate the impacts of turbidity on the water supply

• This presentation describes the models and illustrates how the models have been applied to help inform operational decisions to maintain high quality water at supply intakes.

3

System Description

Kensico

Ashokan Reservoir OptionsD

IVID

ING

WEI

R

EAST BASIN

WESTBASIN

RELEASECHANNELCATSKILL

AQUEDUCT

GATEHOUSE

DIVIDINGWEIRGATE

4

Model Description

Kensico

CEQUAL-W2 Two Dimensional Reservoir ModelsAshokan

Esopus Creek

DividingWeir

CatskillAqueduct

ReleaseChannel

Spillway

Catskill Influent

Catskill Effluent

Delaware Effluent

Delaware Influent

• CEQUAL-W2 Models adapted to simulate turbidity transport by Upstate Freshwater Institute (UFI).

5

Catskill Influent

Catskill Effluent

Delaware Effluent

Delaware Influent

Model Description

Kensico

Turbidity Profile

CEQUAL-W2 Two Dimensional Reservoir ModelsExample Longitudinal Profiles

Temperature

6

E. Br. Delaware R.

Delaware R.

Lackawaxen R.

Mongaup R.

Neversink R.

Lehigh R.

Tohickon Cr.

Musconetong R.

Assunpink Cr.

Crosswicks Cr.

N. Br. Rancocas Cr..Schuylkil l R.

White Clay Cr.

Red Clay Cr.

Tulpehocken Cr.

Jordan Cr.

Dyberry Cr.

W. Br. Lackawaxen R.

Perkiomen Cr.

Maiden Cr.

100

105

110

115

120

125

130

135

140

145

150

155

160

165

17 0

175

185

190

200

205

210

215

220

225

230

235

240

245

250

255

260

265

270

275

280

285

290

295

300

305

310

315

32 0

325

330

335

340

345

350 355

360

365

366

37 0

375 380

385390

395

400

405

410

415

420

425

430

435

440

445 450

455460

465

470

475

480

485

490

495500

505

510

515

520

52 5

530

535

540

545

550

599

600

610

612

615

625

630635

650

655

660

670

675

680

685

690

695

700

705

710715

72 0

722

725

730 735

740

745

750

755

760

765

770

775

780

900

910

991

992

994

995

996

997

999

180

195

620

D&R Canal

657

OASIS Model of

Water Supply System andDelaware River Basin

New York City

JeromePk

Stilesv l

Callic oo

Oak landV

Nev rsR iv

Woodbrne

Mon tague

Por tJe rv

MongpRiv

Hawley __

Wils onv l

Bar ryv il

Tocks Is l

Philadel

Sc huy lk l

Dem_5BPA

Read ing_

BlueMrs h

Po tts twn

Berne___

Landingv

L imerick

Grater fd

ChaddsFd

W ilming t

Demd_8DE

MemBridg

New ark __

Wooddale

Demd_8PA

Chester_

Dem_7BNJ

Dem_5APA

Dem_7ANJ

TrentInc

Demd_4NJ

PPle asn tPipe rsv l

Demd_6PA

Glendon_

Wa lnutp t

Be ltzR iv

W hitehv n

Mer rlTrn

MerrlRes

Belv ider

Lehigh R.

D&R -King

WBrLac kw

Prompton

Honesda l

661

706

621

702 703707

701

699

766

761

FEW alte r

Be ltz ResAquas hic

Palme rtn

Sc hneck s

Allen tw n

Hacke tts

Bloomsby

Noc kamix

AssunCrk

Extonv ilLanghorn

Pe mber tn

To r resd l

Pier II_N

Potts v ilCres sona

Tamaqua_

Drehersv

Virg insv

Blu eMRes

Ches trC k

Jadwin__

Dyberry _

767

768

769 771

671716

676

721711

726

736746

751756

998

Boy dsSplEBrBgSpl

Spil l Nodes

CrD ivSp lM_BraSpl

W_BraSp lCroFlSp l

Titcs SplAmwlkSpl

CrR vrSplMusctSpl

651

EBC rotJn

WJWW_dem

Kn48_dem

Kens _Sp l

WBra_dem

Shaft_11

Shaft_10

CrotJnc 1

CrAq_dem

KH_DelAq KH_CatAq

KnCt_demKnDl_dem

CrotJ nc 2

NC ro_R e l

NC ro_Sp l

RoWB_dem

NwCr_dem

Amaw_dem

Mus c_dem

MBra_dem

Sh aft_9_

Mus cootJW. Br. Delaware R.

Esopus Ck

Wallenpaupack Cr.

MongpR es

Demd_1NY

Demd_1NJ

Demd_1PA

HaleEddy

Down sv il

Harvard_

Fis hEddy

DelBnDiv

Beth lehm

Demd_3PA

Riege ls v

Demd_2PA

Demd_2NJ

Trenton_

Demd_4PA

TT_UpD el

TT_LoDe l

Below Div

Shaft_13

term_599

Shaft_ 17

Scho_Sp l

CrossR vr

Tit icus_

M_B ranch

CrotFall

Amaw alk_

EAs h_Spl

W Ash_Sp l

Allaben_

986

Ron d_Spl

983

Rond_Re l

EBrBogB r

Crot_Div

Ron dout_

993

Sc ho_LLO

WAshokan

EAshokan

Schohari

616

NYork Cty

BQ _Aquif

Hillv iew

898

CannoSp l

897 Pepac Sp l

899

NevrsSpl

Ca nnonsv

NevrsR es

W_Branch

Kens ico_

BoydsC or

Pepac ton

Wallenpa

611As hWas te

Catsk _ In

Shaft_6_Shaft_5A

Che lsea_

CatJunc1

Shaft_4_

RondLoss

Delaware Aqueduct

CatJ_dem

Muscoot_

New_Crot

98 7

MtMar ion

Model DescriptionOASIS system model combined with CEQUAL-W2 Reservoir Models

• OASIS Model used to simulate aqueduct flows and reservoir releases and spills

• Combined OASIS-W2 is backbone of Operations Support Tool (under development)

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Model Development History

• Mid 2000s: W2 models integrated with OASIS system model for analyses of Catskill Turbidity Control Alternatives. (Hazen & Sawyer/Hydrologics/UFI)

• Late 1990s: Two Dimensional water quality models (CEQUAL-W2) developed as part of FAD modeling (UFI).

• Early 2000s: W2 models connected using linked reservoir software (UFI).

• Other Modeling Applications:• Long Term Planning• Recommendations for operating rules• Catskill Turbidity Control Program• Delaware Basin Flexible Flow Management Program (FFMP)• Climate Change Studies

• Mid 2000s: W2 model improvements including use of multiple settling rates for turbidity causing particles, improved resuspension processes and expanded historical time series. (UFI)

• Mid-Late 2000s: OASIS/W2 model used to evaluate alternatives for Catskill Turbidity Control Program. (Hazen & Sawyer/Hydrologics/UFI)

• Late 2000s-Early 2010s: Development of Operations Support Tool (OST) including the integrated OASIS/W2 model along with improved inflow forecasts and data integration. (Hazen & Sawyer/Hydrologics/UFI)

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Reservoir Water Quality Model(CEQUAL-W2)

Meteorologic Input(Temp., RH, Solar Rad) Flows

OASIS Water System Model

Turbidity

Reservoir Storage

Effluent Turbidity

Initial Conditions(Reservoir Water

Temperature/Turbidity Profiles; Reservoir

Storage Levels;Snowpack)

Time Series Input (Forecast)

Initial Conditions (Snapshot)

Model

Results

Model Description – Application Method

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Turbidity

Reservoir Storage

Effluent Turbidity






Model

Results


• Current reservoir water surface elevations

• Limnological surveys• Data from automated

profiles of water column temperature and turbidity

• Snow survey results

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Turbidity

Reservoir Storage

Effluent Turbidity






Model

Results

Model Description – Application Method• Forecast based on historical record or weather service analysis• Multiple traces representing many potential future input time

series

11




Turbidity

Reservoir Storage

Effluent Turbidity






Model

Results


Multiple time series results representing each of the forecast traces

12

Model run for 57 inflow traces based on historical flow and meteorologic record (1948-2004)

Statistics of traces can be translated to cumulative probability function

Model Description – Application MethodExample of Position Analysis

13

Modeling Applications History

0

5

10

15

20

2005 2006 2007 2008 2009 2010 2011 2012 2013

# of

Mod

elin

g An

alys

es

Year

0

5

10

15

20

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

# of

Mod

elin

g An

alys

es

Month

Number of Modeling Analyses by Year

Number of Modeling Analyses by Month

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Model Simulations Late February 2010• Large storm at the end of January 2010 filled

the Ashokan Reservoir and elevated turbidity in the West Basin of the reservoir.

• If another large storm event were to occur in late February, the West Basin would spill to the East Basin, creating elevated East Basin turbidity.

• A series of CEQUAL-W2 reservoir model simulations and OASIS system model simulations were performed to understand how the use of the Ashokan release channel reduces the risk of higher turbidity water in the West Basin spilling over the dividing weir and entering the East Basin.

0

4000

8000

12000

16000

1-Jan 31-Jan 2-Mar 1-Apr 1-MayDate - 2010

Flow

(cfs

)

1

10

100

1000

10000

1-Jan 31-Jan 2-Mar 1-Apr 1-MayDate - 2010

Turb

idity

(NTU

)

Esopus Creek Inflow

Esopus Creek Turbidity

Sample Analysis – Ashokan Reservoir

Esopus Creek

DividingWeir

CatskillAqueduct

ReleaseChannel

Spillway

15

1

10

100

1000

2-Feb 16-Feb 1-Mar 15-Mar 29-Mar 12-Apr 26-Apr

Date - 2010

East

Bas

in W

ithdr

awl T

urbi

dity

(N

TU)

1

10

100

1000


Date - 2010

East

Bas

in W

ithdr

awl T

urbi

dity

(N

TU)

Model Simulations Late February 2010

0

0.2

0.4

0.6

0.8

1


Date - 2010

Frac

tion

of tr

aces

with

Tu

rbid

ity >

10

NTU

on

or b

efor

e D

ate

Position Analysis Traces

Release Channel = 0 MGD

Release Channel = 350 MGD

Cumulative ProbabilityFraction of Traces with

Turbidity > 10 NTU on or before date

Eas

t Bas

in W

ithdr

aw T

urbi

dity

(NTU

)

Simulation Date - 2010

Simulation Date - 2010Release Channel = 0 MGDRelease Channel = 350 MGD

Probability of turbidity exceeding 10 NTU by end of three month simulation period reduced from near 95% to about 35%


16

0.00

0.20

0.40

0.60

0.80

1.00

2-Feb 16-Feb 2-Mar 16-Mar 30-Mar 13-Apr 27-AprDate - 2010

Frac

tion

of T

race

s w

ith F

irst S

pill

on o

r bef

ore

Dat

e

Model Simulations Late February 2010

Cumulative ProbabilityFirst Date of Spill from West Basin to East

Simulation Date - 2010Release Channel = 0 MGDRelease Channel = 350 MGD

• Using release channel significantly delays and reduces risk of spill from West Basin to East Basin.

• Delay and reduction in spill reduces risks of elevated turbidity in East Basin

• Delay and reduction in West to East Spill also reduces risk and amount of spill from East Basin.


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Meteorologic Input(Temp., RH, Solar Rad)

Flows Turbidity

Effluent Turbidity


Temperature/Turbidity Profiles)



Model

Results

Model Description – Application MethodKensico Sensitivity Model Application

18



Flows Turbidity

Effluent Turbidity





Model

Results


• Current reservoir water surface elevations

• Limnological surveys• Data from automated

profiles of water column temperature and turbidity

19



Flows Turbidity

Effluent Turbidity





Model

Results


• Forecast based on historical record or weather service analysis• Multiple traces representing many potential future input time

series

20



Flows Turbidity

Effluent Turbidity





Model

Results


Prescribed constant time series based on expected turbidity and potential flow rates from upstream reservoirs (via aqueducts)

21



Flows Turbidity

Effluent Turbidity





Model

Results


For each combination of fixed turbidity and flow inputs the model produces multiple traces of turbidity results based on the meteorologic input traces

22

0

4000

8000

12000

16000

20000

1-Jan 2-Mar 1-May 30-Jun 29-Aug 28-Oct 27-Dec

Flow

(cfs

)

Date - 2010

0

500

1000

1500

2000

2500

1-Jan 2-Mar 1-May 30-Jun 29-Aug 28-Oct 27-Dec

Turb

idity

(NTU

)

Date - 2010

Esopus Creek Inflow

Esopus Creek Turbidity

Catskill Influent

Catskill Effluent

Delaware Effluent

Delaware Influent

• Large event in October produced large input of turbidity to Ashokan Reservoir. There was a large impact on Ashokan diversion turbidity and stop shutters were employed to reduce flow to Kensico Reservoir.

• Kensico 2D reservoir model used to determine effects of elevated turbidity and various Catskill Aqueduct flow rates on Kensico Reservoir effluent.

(20 or 40 NTU)(50, 150 or 250 MGD) (1150, 1050 or

1000 MGD)

(1.5 NTU)

(400 MGD)

(800 MGD)

Sample Kensico AnalysisOctober 2010

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October 2010Simulated Catskill Effluent Turbidity

20 NTU

40 NTU

These runs indicated that if Catskill influent turbidity was above 20 NTU flow rate should be reduced to 150 MGD. If Catskill influent turbidity rises to about 40 NTU for an extended period, then flow should be reduced to about 50 MGD.

Catskill Aqueduct Inflow

0.0

2.5

5.0

7.5

10.0

1-Oct 8-Oct 15-Oct 22-Oct 29-Oct0.0

2.5

5.0

7.5

10.0

1-Oct 8-Oct 15-Oct 22-Oct 29-Oct

0.0

2.5

5.0

7.5

10.0

1-Oct 8-Oct 15-Oct 22-Oct 29-Oct0.0

2.5

5.0

7.5

10.0


CatskillAqueduct Influent Turbidity

150 MGD 250 MGD

0.0

2.5

5.0

7.5

10.0


0.0

2.5

5.0

7.5

10.0


50 MGD

Sample Kensico Analysis

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Conclusions

• Over the last decade DEP has developed and applied an extensive suite of water quality and water system models to analyze turbidity transport within the Catskill System Reservoirs.

• DEP’s water quality models have been effectively used to help inform operational decisions to minimize use of alum and turbidity at water supply intakes.

• Development and application of these models continues under the Operations Support Tool project.

Water Quality Modeling used to Inform Operational Decisions for the NYC Water Supply:

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