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