Recent Storm Activity and its Effect on Turbidity Levels in Neversink Reservoir

Rich Van Dreason

Watershed Water Quality Science and Research

New York City Department of Environmental Protection

NYC Watershed/Tifft Science & Technical Symposium

September 19 , 2013 Thayer Hotel, West Point

2

Introduction

August 29, 2011

Neversink River just below dam

September 19, 2012

Neversink Reservoir

Neversink Reservoir not too long ago

September 19, 2012

Neversink River above reservoir

3

Objectives

Discuss factors associated with recent elevated turbidity in the Neversink Reservoir

• Occurrence of recent large storm events

• Increase in sources of turbidity resulting from Irene

Discuss factors that may be contributing to the slow recovery since Irene

o Occurrence of small storm events

o Particle size

Recent monitoring upgrades

4

Land use in the Neversink Basin

5

Hydrology and site locations in Neversink basin

West Branch

East Branch

Aden Brook

Kramer Brook

NR4

NR3

NR2

NR1

10

20

30

40

Neversink Reservoir (cross-section)

6

Turbidity Characteristics

Definition:

•Measure of the light-scattering effects of suspended particulate material.

o Nephelometer; results in NTU

Turbidity=-0.01435 + 0.7135 (TSS)

R-sq=85.7%

• Suspended particles that contribute to turbidity are generally in the 1-10 micron range

o Examples: clay, fine silt and algae

• SWTR Source Water turbidity limit = 5 NTU

• Turbidity is related to suspended sediment concentrations

o Also depends on the particle size distribution and refractive index which may change with turbidity source

7

Turbidity and Stream flow

• Complex relationshipo Available sediment supply

o Location of sediment supply

• High turbidity at onset => available material in channel

• High turbidity later on hydrograph

o Sediment sources faraway

o New sediment sources become available

8

Mean Daily Flow(cfs)F

LO

W_C

FS

010002000300040005000600070008000

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Main stem Neversink River

Neversink River @ NCG

the

mea

n, t

urb

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Mean_taps

MeanTurbidity

(NTU)

Long-term turbidity at Neversink Reservoir and Streams

Reservoir Elevation taps (1-4)

1.2.

3.

Turbidity (NTU)

PRE POST

MeanMax

1.830

8.5200

October 1, 2010

Pre conditions Post

Tu

rbid

ity(

NT

U)

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Main stem Neversink River

Tu

rbid

ity(

NT

U)

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Aden Brook_Neversink basin

Neversink River (NCG)

Aden Brook (NK4)

Turbidity(NTU)

Tu

rbid

ity(

NT

U)

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Kramer Brook_Neversink basin

Kramer Brook (NK6)

Year

MeanMax

0.860

1.926

MeanMax

1.122

1.918

MeanMax

3.7150

3.412

9

Mean Daily Flow(cfs)F

LO

W_C

FS

010002000300040005000600070008000

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Main stem Neversink River

Neversink River @ NCG

the

mea

n, tu

rb

0

50

100

150

200

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Mean_taps

MeanTurbidity

(NTU)

Reservoir Elevation taps (1-4)

Tu

rbid

ity(

NT

U)

0.0

50.0

100.0

150.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Main stem Neversink River

Tu

rbid

ity(

NT

U)

0.0

50.0

100.0

150.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Kramer Brook_Neversink basin

Neversink River (NCG)

Kramer Brook (NK6)

Aden Brook (NK4)

Long-term turbidity at Neversink Reservoir and Streams

1.2.

3.

Turbidity(NTU)

?

Tu

rbid

ity(

NT

U)

0.0

50.0

100.0

150.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Aden Brook_Neversink basin

Year

Monthly stream samples not adequate for flashy mountain streams

?

?

?

10

Details of recent flow eventsF

LO

W_C

FS

010002000300040005000600070008000

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Neversink River

Mean Daily Flow(cfs)

Neversink River @ NCG

• Event 2 Aug 28, 2011 (Irene)• Daily mean flow was 7,220 cfs

(largest on record)• Peak flow was 20,900 cfs (60 yr

event, 2nd largest)• 4.8 inches Aug 27-28, 3.6 inches

on Aug 15• Event 3 Sept 18, 2012 • Daily mean flow was 3410 cfs• Peak flow was 17,800 cfs • ( 45 yr. flood, 4th largest) • 5.3 inches Sept 17-18 • (localized).

• Event 1 Oct 1, 2010 • Daily mean flow was 6030 cfs• Peak flow was 16,400 cfs (about 20

yr flood, 6th largest) • 7.8 inches 5 days prior w/ 5.7 on

Sep. 30

the

mea

n, t

urb

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Mean_taps

162.5 NTU

59.5 ntu29.6 NTUMean

Turbidity(NTU)

Reservoir Elevation taps (1-4)

11

Turbidity Recovery Rates

Why the slow recovery after Event 3 ???

the

mea

n, t

urb

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Mean_taps

Reservoir Elevation taps (1-4)

the

mea

n, t

urb

0.1

1.0

10.0

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Mean_taps

MeanTurbidity

(NTU)

124 days

130 days

162.5 NTU

59.5 ntu

2.7 ntu 3.8 ntu

40% higher(3.2 vs. 1.9 NTU)

MeanTurbidity

(NTU)Low

Range

FL

OW

_CF

S

010002000300040005000600070008000

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Neversink River

29.6 NTU

1.6 ntu

28 days

1.2.

3.

1430 cfs

1180 cfs1270 cfs

Event 1 Event 2 Event 3

Mean Daily Flow(cfs)

Higher resolution stream data needed!

Tu

rbid

ity(

NT

U)

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Aden Brook_Neversink basin

0.3 0.3

1.30.5 0.3 0.3

1.30.3 0.2

0.4 0.5

5.6

0.20.9 1.5 0.8

0.4 0.5 0.9

5.81.6

0.5 0.4 0.63.0

0.5 0.8 0.5 0.7 0.4 0.4 0.4 0.3 0.3

6.31.4

18.0

0.5

5.6 3.51.0

2.1

0.3

Neversink River (NCG)

Turbidity(NTU)

Historic 95th percentile (1.9 ntu)

12

Additional factors - particle size

Post Irene, Upstate Freshwater Institute (UFI) contracted to evaluate turbidity causing particles in the Delaware Reservoirs

• Size distribution and composition

• Scanning electron microscopy interfaced with Automated image and X-ray analyses

From “Hurricane Irene Turbidity Studies” prepared by Upstate Freshwater Institute December 14, 2012

Neversink Results

80% of turbidity caused by particles < 4 µm

Composition: 69% clay, 18% quartz

Particle size

Settling rate

13

Neversink Basin Surficial Geology

Most deposits contain very little fine sediment

Glacial till most likely source of small particles

• Very abundant

Streams are often in close proximity to the glacial tills

Tills generally tightly packed; impermeable

14

Eroding glacial till hillslopes

Hypothesis

• High flows caused new hillslope failures (or exploited old ones) freeing fine sediment to become entrained

Currently 15 large failures in till (>1000 sq. ft. eroding bank)

• Some old but enlarged, some initiated by Irene

How much fine material? How transportable?

15

What about glacial lake clays?

Exposed glacial lake clays are rare in the main branches of Neversink River

Smaller tributaries still to be assessed

Figure 5. Channel incision into lacustrine deposits post Irene.

W. Branch Neversink upstream of Frost Valley (December 2011)

16

Real time turbidity data is here!

Digital Turbidity, Temperature Sensors and Data logger

• Forest Technology Systems and Campbell Scientific

Real-time data access via phone-line

Benefits

• Early warning

• Evaluate flow-turbidity relationship

• Basin changes

17

Vertical Profiling Systems

YSI vertical profiling system to be installed next year

• Turbidity, temperature, conductivity, dissolved oxygen etc.

• Real-time data access via radio modem to land line connection

Benefits

• Early-warning

• Track turbidity interflows

• Monitor resuspension

• Select appropriate intake

18

Conclusions Recent elevated turbidities in Neversink Reservoir related to large storm

events starting on October 1, 2010

the

mea

n, t

urb

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Mean_taps

Turbidity(NTU)

Elevation taps (1-4)

Mean Daily Flow(cfs)F

LO

W_C

FS

010002000300040005000600070008000

Date Collected

87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

Main stem Neversink River

Neversink River @ NCG

And possibly to greater availability of fine sediment courtesy of Irene

19

Conclusions (continued)

Longer recovery periods post Events 2 and 3 associated with:

• Occurrence of multiple storm events following initial major event

Mean Daily Flow(cfs)

the

mea

n, t

urb

0.1

1.0

10.0

50.0

100.0

200.0

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Mean_taps

FL

OW

_CF

S

010002000300040005000600070008000

Date Collected

JAN10

FEB10

MAR10

APR10

MAY10

JUN10

JUL10

AUG10

SEP10

OCT10

NOV10

DEC10

JAN11

FEB11

MAR11

APR11

MAY11

JUN11

JUL11

AUG11

SEP11

OCT11

NOV11

DEC11

JAN12

FEB12

MAR12

APR12

MAY12

JUN12

JUL12

AUG12

SEP12

OCT12

NOV12

DEC12

JAN13

FEB13

MAR13

APR13

MAY13

JUN13

JUL13

AUG13

Neversink River

Reservoir Elevation taps (1-4)

MeanTurbidity

(NTU)

124 days

130 days

162.5 NTU

59.5 ntu

2.7 ntu 3.8 ntu

29.6 NTU

1.6 ntu

28 days

Multiple events Multiple events

20

Conclusions (continued)

• And possibly from an increase of clay-sized particles derived from eroding banks of glacial till

Glacial till bank

Exposed lake clay deposit

21

Questions ?

22

Conclusions

Recent elevated turbidities in Neversink Reservoir related to :

Large storm events starting on October 1, 2010

And possibly to greater availability of fine sediment

Longer recovery periods post Events 2 and 3 associated with:

Occurrence of multiple storm events following initial major event

And possibly from an increase of clay-sized particles derived from eroding banks of glacial till and recent exposures of lacustrine clays

23

Additional factors - particle size

Neversink Particle Size Distribution Post Irene, Upstate Freshwater Institute determined the size distribution of turbidity causing particles in all Delaware Reservoirs

Scanning electron microscopy interfaced with Automated image and X-ray analyses

Particle cross-sectional Area per unit Volume of water (PAV) strongly correlates to turbidity.

Modified from “Hurricane Irene Turbidity Studies” prepared by Upstate Freshwater Institute December 14, 2012

Key Findings

80% of turbidity caused by particles < 4 µm, substantially smaller than other Delaware Reservoirs

4 µm upper limit of clay-sized particles

4

Other Delaware reservoirs

24

Conclusions (continued)

• And possibly from an increase of clay-sized particles derived from eroding banks of glacial till

Neversink Particle Size Distribution

Glacial till bank

Exposed lake clay deposit

4

25

0

5

10

15

20

1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

0

10

20

30

40

1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Extreme flow event trends in Neversink basin

0

10

20

30

40

1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Mean Daily Flows>95th percentile (579 cfs)

All months

Cold season(November-May)

Warm season(June-October)

Inspired by Matonse A. H. and A. Frei (In press)

All major Catskill streams show similar trends

o Schoharie Creek, Esopus Creek, E. and W. Branch of Delaware River

26

Additional Factors? More resuspension after Events 2 and 3?

o Unknown; no data

Did particles settle more slowly after Events 2 and 3?

o DOC tends to prevent aggradation of particles

o Settling rates decrease with decreasing water temperature, particle size

Recovery period (days)

DOC (mgL-1) Temp (C)

Event 1 28 2.5 (2.2) 8.2 (7.6)

Event 2 124 2.9 (2.1) 10.2 (8.2)

Event 3 130 2.5 (2.2) 7.8 (6.7)

Slow recovery not related to DOC and temperature

Particle size?

27

1

2

3

4

Turbidity interflow post Irene