PDF File of Talk
Effects of Bulkheads on Estuarine Beach Swash Zone Processes and Characteristics Nicole A. A Raineault Raineault, Rutgers University [email protected]
Karl F. Nordstrom,, Rutgers g Universityy Nancy L. Jackson, New Jersey Institute of Technology
Delaware Estuary Science & Environmental Summit 2009
Background: Bulkheads
Bulkheads protect infrastructure from erosion
Bulkhead Effects on Estuarine Beaches •Higher frequency of erosion/accretion •Smaller Smaller overall net surface change •Increased depth of sediment activation •Bulkhead design matters •Enclaves altered
Process Alterations Interrupts longshore transport Prevents migration of swash/waves Creates reflected wave and swash energy Increases turbulence
Field Design
Average Conditions: 8-22 June 2007
Wind Speed: 2.0 ms-1 Wind Direction: SSE Significant Wave Height: 0.18 m
Topographic Variability
50 40
Average Low‐Energy Net Change ‐8
‐6 ‐4 ‐2
0
2
4
6
30
Net change (m mm)
20 10 0 ‐10 ‐20 ‐30 ‐40
Control
Bulkhead North Bulkhead South Bulkhead South
Location of Bulkhead North
‐50
Cross‐shore distance (m)
8
10
Average Low Energy Depth of Sediment Activation
De epth of sediment acctivation ((mm)
0
0
2
4
6
8
10
‐50 Control
‐100 Bulkhead South ‐150 150
Bulkhead North Bulkhead North ‐200
Increased depth of sediment activation at bulkheads
High Energy Event: 22 June
Wi d Speed: Wind S d 7.7 ms-11 Wind Direction: NW Significant Wave Height: 0.28 m
High Energy Net Change
Net Chaange (mm)
100 50
Bulkhead North
Bulkhead South
0 ‐50 C Control l
‐100
High Energy Depth of Sediment Activation 0
1
2
3
4
5
6
7
Depth o of sediment activation (mm)
‐5 ‐25 ‐45 ‐65 85 ‐85 ‐105 ‐125
Cross‐shore distance (m)
8
9
10
11
Process Alterations Incident Wave
Reflected Wave
Planar vs Buttressed Bulkheads
Enclave Locally L ll increased i d sediment activation
Increased surface change and sediment d mobility bl
Conclusion
Bulkheads create zones of swash reflection and wave interaction I Increasing: i Frequency of erosion/accretion reversals Depth p of sediment activation Design makes a difference Enclaves experience alterations
Thanks to: Sher Saini and Diana Reyes, New Jersey Institute of Technology New Jersey Sea Grant, NOAA
Karl F. Nordstrom,, Rutgers g Universityy Nancy L. Jackson, New Jersey Institute of Technology
Delaware Estuary Science & Environmental Summit 2009
Background: Bulkheads
Bulkheads protect infrastructure from erosion
Bulkhead Effects on Estuarine Beaches •Higher frequency of erosion/accretion •Smaller Smaller overall net surface change •Increased depth of sediment activation •Bulkhead design matters •Enclaves altered
Process Alterations Interrupts longshore transport Prevents migration of swash/waves Creates reflected wave and swash energy Increases turbulence
Field Design
Average Conditions: 8-22 June 2007
Wind Speed: 2.0 ms-1 Wind Direction: SSE Significant Wave Height: 0.18 m
Topographic Variability
50 40
Average Low‐Energy Net Change ‐8
‐6 ‐4 ‐2
0
2
4
6
30
Net change (m mm)
20 10 0 ‐10 ‐20 ‐30 ‐40
Control
Bulkhead North Bulkhead South Bulkhead South
Location of Bulkhead North
‐50
Cross‐shore distance (m)
8
10
Average Low Energy Depth of Sediment Activation
De epth of sediment acctivation ((mm)
0
0
2
4
6
8
10
‐50 Control
‐100 Bulkhead South ‐150 150
Bulkhead North Bulkhead North ‐200
Increased depth of sediment activation at bulkheads
High Energy Event: 22 June
Wi d Speed: Wind S d 7.7 ms-11 Wind Direction: NW Significant Wave Height: 0.28 m
High Energy Net Change
Net Chaange (mm)
100 50
Bulkhead North
Bulkhead South
0 ‐50 C Control l
‐100
High Energy Depth of Sediment Activation 0
1
2
3
4
5
6
7
Depth o of sediment activation (mm)
‐5 ‐25 ‐45 ‐65 85 ‐85 ‐105 ‐125
Cross‐shore distance (m)
8
9
10
11
Process Alterations Incident Wave
Reflected Wave
Planar vs Buttressed Bulkheads
Enclave Locally L ll increased i d sediment activation
Increased surface change and sediment d mobility bl
Conclusion
Bulkheads create zones of swash reflection and wave interaction I Increasing: i Frequency of erosion/accretion reversals Depth p of sediment activation Design makes a difference Enclaves experience alterations
Thanks to: Sher Saini and Diana Reyes, New Jersey Institute of Technology New Jersey Sea Grant, NOAA
