STORM SURGE ATTENUATION IN CHESAPEAKE BAY WETLANDS

Transcription

1 STORM SURGE ATTENUATION IN CHESAPEAKE BAY WETLANDS Seth Lawler, Dr. Celso Ferreira Department of Civil, Environmental and Infrastructure Engineering 1

2 Background: Surge & Natural Defenses

3 Background: USACE Rule of Thumb : Storm Surge reduced 1 m per every 2.7 km of marsh Basis: Report correlated storm surge elevations for seven storms occurring across Southern Louisiana between 1909 and 1957 (Corps of Engineers, 1963). Scatter: Attenuation rates range from 1 m per 60 km to 1 m per 5 km (differing by a factor of 12). (Wamsley et al., 2010). 3

4 Objectives Specific Aim: Improved scientific understanding of storm surge flow in coastal wetlands Field Work Characterization of Vegetation Water level monitoring High Performance Computing Geospatial Analysis ADCIRC + SWAN 4

5 Field Work Vegetation Survey Water level Monitoring 5

6 Vegetation Characteristics: Summer & Winter 2015 Frontal Area Biomass Bio-mechanical Properties Seasonal Variation 6

7 Water Level Monitoring EVNWR: Tidal Records EVNWR Water Levels DMNAP Water Levels EVNWR Barometric Pressure 7

8 Monitoring Sites Dameron Marsh Natural Area Preserve Magothy Bay Natural Area Preserve Eastern Shore of Virginia National Wildlife Refuge 8

9 Eastern Shore of Virginia National Wildlife Refuge 9

10 Magothy Bay Natural AreaPreserve 10

11 Dameron Marsh Natural Area Preserve 11

12 Water Level Data Sensor 5 (ESVNWR) Sensor 4 Sensor 3 Sensor 2 Sensor 1 Preliminary Data: 12

13 Data Availability 13

14 Field Work: Next Steps Vegetation Characterization (Summer 2015) Increase water level monitoring capabilities 14

15 HPC: Modeling Storm Surge Stampede Cluster at U. Texas 15

16 High Performance Computing Storm Surge Model: Coupled ADCIRC + SWAN Base Mesh: FEMA Region III Photo courtesy of caseydietrich.com 16

17 Model Forcing: HURDAT Hurricane Isabel (2003) Hurricane Floyd (1999) 17

18 Model Validation: Hurricane Isabel (2003) 18

19 Model Sensitivity: Resolution FEMA Region III 100m Topo-bathy 50 50m Topo-bathy 10 10m 19

20 Sensitivity Results: 100m vs 10m Resolution 20

21 Model Sensitivity: Friction Uniform Manning s n at selected nodes Manning s n from NLCD 21

22 Spatial Scale: > 2km NLCD Friction High Friction 22

23 Model Sensitivity: Friction 23

24 Spatial Scale: <2km NLCD Friction High Friction 24

25 Sensitivity Results: High, Low, NLCD 25

26 Sensitivity Results: High, Low, NLCD 26

27 USACE Revisited Rule of Thumb : Storm Surge reduced 1 m per every 2.7 km of marsh That can t be right?... Modeling Results: Also show high degree of scatter even at the same spatial scale Potential Drivers: Storm Characteristics Geographic Context 27

28 Future Work Field Work: Vegetation Characterization (Summer 2015) Increase water level monitoring capabilities Modeling: Conclude Sensitivity Analysis Sub-domain Modelling Engineering: Evaluate Design Alternatives 28

29 Questions? The views expressed herein are those of the research group and do not necessarily reflect views of our sponsors or any sub agencies. The use of trade names does not constitute an endorsement in the use of these products by the U.S. Government 29

30 References Choi, J. and Harvey, J.W., Relative significance of microtopography and vegetation as controls on surface water flow on a low-gradient floodplain, Wetlands, doi: /s United States Army Corps of Engineering (1963), US Army District, New Orleans, Interim Survey Report, Morgan City, Louisiana and Vicinity, serial n. 63. Wamsley, T.;Cialone, M.; Smith, J.M.; Ebersole, B.A. and Grzegorzewski, A. S. (2010). "The potential of wetlands in reducing storm surge." Ocean Engineering, Wu, W., Ozeren, Y., Wren, D.G., Chen, Q., Zhang, G., Holland, M., Ding, Y., Kuiry, S.N., Zhang, M., Jadhave, R., Chatagnier, J., Chen, Y., Gordji, L Investigation of surge and wage reduction by vegetation: final report of phase I. Laboratory Publication. 1:315. Wu, W., Ozeren, Y., Wren, D.G., Chen, Q., Zhang, G., Holland, M., Ding, Y., Kuiry, S.N., Zhang, M., Jadhave, R., Chatagnier, J., Chen, Y., Gordji, L Investigation of surge and wage reduction by vegetation: final report of phase I. Laboratory Publication. 1: