An Examination of Winyah Bay,South CarolinaUnder Two Different Flow Conditions

Kathryn Benson

CE 394K GIS in Water Resources

University of Texas at Austin

Fall 2002

Where to start?

•Data Acquisition from the University of South Carolina

• EPA River Reach File-Region 03

•USGS Hydrologic Cataloging Unit

OBJECTIVE

To examine the mixing characteristics of Winyah

Bay, South Carolina under two different streamflow conditions

BLACK

LUMBER

ROCKY

LOWER PEE DEE

UPPER YADKIN

LYNCHES WACCAMAWLITTLE PEE DEE

LOWER YADKINSOUTH YADKIN

UPPER PEE DEE

CAROLINA COASTAL-SAMPIT

Watershed Characteristics

Second largest watershed on the Atlantic Coast

3 States

12 HUCS

Black

Lynches

Pee Dee

Waccamaw

Little PD

Streamflow Conditions

Five Main Rivers flow into Winyah Bay

Define streamflow for two days of sampling

High vs. average flow conditions due to snowmelt

Use of Time Series Function

Average Daily Streamflow

0

2000

4000

6000

8000

10000

12000

Black River Pee Dee River Little Pee Dee River Waccamaw River Lynches River

Str

eam

flo

w (

cfs

)

17-Apr-99

12-Feb-00

Average Streamflow, February 12, 2000 River Flow (cfs)

Black River 1807.08Pee Dee River 10529.17Little Pee Dee River 6944.58Wacacmaw River 3912.08Lynches River 1972.5

Total Flow (cfs) Average Flow (cfs)25165.41 5033.08

Average Streamflow, April 17, 1999 River Flow (cfs)

Black River 338.5Pee Dee River 2124.69Lower Pee Dee River 1775.42Wacacmaw River 1390.42Lynches River 481.54

Daily Total Flow (cfs) Daily Average Flow (cfs)6110.57 1222.11

WB499.9

WB499.7

WB499.4

WB499.14

WB499.13

WB499.10

WB200.7

WB200.6

WB200.5

WB200.14

WB200.13

WB200.11

WINYAH BAY, SC

68.3 km2 or 26.3 mi2

Six sampling sites per day for ebbing tide (freshwater towards ocean)

Interface between freshwater and saltwater is extended over approximately a 10 km area from the rivers to the mouth of Winyah Bay (Zabawa, 1979)

Mixing point for low flow is WB499.9 Partially Mixed Estuary

Mixing point for high flow is WB200.13 River Dominated Estuary

WB499.9

WB499.7

WB499.4

WB499.14

WB499.13

WB499.10

Salinity Profiles During an Ebbing Tide from the Rivers to the Mouth

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25 30 35 40

Salinity (psu)

Dept

h (m

)

WB499.14

WB499.13

WB499.9

WB499.10

WB499.7

WB499.4

Salinty Profiles durring an ebbing tide from the Rivers to the Mouth

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25 30 35 40

Salinity (psu)

WB 200.5

WB 200.6

WB 200. 7

WB 200.14

WB 200.13

WB 200.11

WB200.7

WB200.6

WB200.5

WB200.14

WB200.13

WB200.11

CTD

NISKIN

What else does streamflow effect?

Chemical Processes

Nutrient Concentrations

Suspended Material

Non-point Source Pollution

Point Source Pollution

Surface Channel Chemical Trends, April 17, 1999

0.000

5.000

10.000

15.000

20.000

25.000

30.000

35.000

0 1 2 3 4 5 6 7

Sample Sites

0.100

0.300

0.500

0.700

0.900

1.100

1.300

1.500

1.700

1.900

DOC (mg/l)

Chl A (mg/l)

NO3 (µg Atm./l)

OP (µg Atm./l)

Surface Channel Chemical Trends, February 12, 2000

0.000

5.000

10.000

15.000

20.000

25.000

30.000

35.000

0 1 2 3 4 5 6 7

Sample Sites

0.100

0.300

0.500

0.700

0.900

1.100

1.300

1.500

1.700

1.900

DOC (mg/l)

Chl A (mg/l)

NO3 (µg Atm./l)

OP (µg Atm./l)

Higher Nutrient concentration

Total Suspended Matter (TSM), April 17, 1999

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7

Sample Sites

TS

M (

mg

/L)

TSM (mg/l) Surface

TSM (mg/l) Bottom

Total Suspended Matter (TSM), Feb. 12, 2000

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7

Sample Sites

TSM (mg/L)SurfaceTSM (mg/L) Bottom

Higher concentration of TSM with higher streamflow

Correll, D.L., 1998. The Role of phosphorus in the eutrophication of receiving waters: A review. Journal of Environmental Quality 27:(2). Pp. 261-266. Falhowski, P.G. and J.A. Raven, 1997. Aquatic Photosynthesis. Blackwell Science, Lt. 2. pp. 310-311. Horton, H.R., L.A. Moron, R.S. Ocha, J.D. Rown, and K.G. Scriagaer, 1996. Principles of Biochemistry: 2nd edition. Prentice-Hall, Inc. pp. 498-499. Troup, B. N. and Bricker, O. P, 1975. Processes Affecting the Transport of Materials from the Continents to Oceans. Marine Geochemistry in the Coastal Environment: American Chemical Society. Zabawa, Christopher F., 1979. Estuarine Sediments and Sedimentary Processes in Winyah Bay, South Carolina. South Carolina Geological Society: Geologic Notes 23;(2). Pp. 79-117.

USGS website- HUCs, NHD, State geography and waterbodies, gaging station and NWIS data (http://www.usgs.gov)

EPA website-surf your watershed, river reach file (http://www.epa.gov)

South Carolina Department of Natural Resources-orthophotos (http://dnr.state.sc.us)

ESRI-data library and help function