estimating tidal sediment erosion in maryland

Estimating Tidal Sediment Erosion in Maryland

Jeffrey Halka

Lamere Hennessee

Katie Offerman

Department of Natural Resources

Resource Assessment Service

Maryland Geological Survey

5000 feet

White = 1845

Blue = 1942

Yellow = 1989

Example from

Tilghman Island

DSAS Example

-7 6 .6 -7 6 .4 -7 6 .2 -7 6 .0 -7 5 .8

L on g itu d e , D eg rees , N A D 8 3

38 .0

38 .2

38 .4

38 .6

38 .8

39 .0

39 .2

39 .4

39 .6

Latit

ude,

Deg

rees

, NA

D83

1

2

3

4

5

67

8

9

10

1112

13

1516

17

17 A

1819

19 A

20

21

22

23

2425

S a m p lin g L o ca tio n s an d R ea ch S eg m en ts

D O R 4 R e ach S eg m en t

1 0 S am p lin g L o ca tio n

C E C 1

H A R

H A R

C E C 2

K E N T 1

K E N T 1

K E N T 2

Q A

T A L

D O R 1

D O R 2

D O R 2

D O R 3

D O R 4 S O M 1

S O M 3

SO M 2S O M 4

StM

C A L

C A L

A A 5

A A 4

A A 3

A A 2

A A 1

B A L 2

B A L 1

S tM

K ilom e te rs

0 1 0 2 0 3 0 4 0

Bank Sample

Locations

MD Data available

• 6,944 miles of shoreline mapped• 242,883 transects• Average erosion rate of 20 cm/yr• Grain size/nutrients at 34 locations

Basic Data Issues• Measure of linear retreat

– Vertical data from USGS Topographic sheets• Bank composition

– Only from selected locations– Both bluff/bank and marsh

• Emplacement of shoreline structures– Impact on average erosion rate calculation

5000 feet

White = 1845

Blue = 1942

Yellow = 1989

Example from

Tilghman Island

VIMS - Center for Coastal Resources Management (CCRM)

Basic Data Issues - 2

• Incomplete error analysis of historical erosion rate measurements

• Both accuracy and resolution issues in areas of low erosion rate

• Fastland vs. nearshore erosion

Shoreline ErosionFastland and Nearshore

Dan cliff sampling