Limited Data, Complex Coastline and Successful Wave Modeling Challenges, Solutions and Lessons Learned

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1 Limited Data, Complex Coastline and Successful Wave Challenges, Solutions and Lessons Learned Paula Kulis, PhD Nader Mahmoudpour, PhD Lauren Klonsky June 11, 2013

2 Purpose Objectives Wave Procedure Challenges Model configuration Model validation Solutions Lessons Learned 2

3 Study Objective Coastal Flood Hazard Analysis of Maine Coast York Cumberland Sagadahoc Lincoln Knox Waldo Hancock 1-Percent-Annual-Chance Wave Conditions Region 1: Event-based study Develop model of wave energy Nor easter 3

4 Features of Study STWAVE v. 6 Halfplane Large Area (200 miles alongshore) Irregular coastline Rocky Islands, Peninsula features Different areas have different dominating risks Offshore waves Surge Near-shore wave data limitations 4

5 Original Plan: Use WIS Identify key representative buoys Boundary conditions validation Local bathymetry Distribution in study area Identify storms with large H Use Extremal Plots Obtain full wave spectrum 5

6 Original Plan: Use WIS Bob Jensen at ERDC Identify key representative buoys Boundary conditions validation Local bathymetry Distribution in study area Identify storms with large H Use Extremal Plots Obtain full wave spectrum 6

7 Validation Troubles Storm Observed Wave Height Modeled Wave Height WIS Modeled Height December m 4.4 m m January m 5.3 m 5.5 m October m 4.9 m m Modeled H is off by ~ 2 m!! 7

8 WIS Validation Troubles 8

9 Limited Data Have off-shore NDBC buoy data: is most comprehensive NDBC data includes: Total energy (H) Limited spectral data No direction data Wind speed/direction 9

10 Complex Coastline Multiple scales in same model Large scale: Offshore buoys driving model Boundary conditions Small scale: bathy and coastline curvature on order of tens of meters Solution: Nested grids 10

11 Methods STWAVE v 6 half-plane Regular grid USACE, SMS GUI Wave action equation Steady State Nesting 3 levels 500 m m 11

12 Validation Data Used: Wave Energy Spectrum NDBC 44005: Focus on 2 storm events (based on validation data availability) 12/17/ /9/2009 Wave height from buoy Standard JONSWAP spectrum Wave direction from wind record Wind Speed (m/s) and Wave Height (m) /9/09 12:00 12/10/09 0:00 12/10/09 12: Obs Wind Speed Wind Direction 150 Degree 12

13 Data Used: Tide, Wind Wind: Buoy 44005, time of peak wave height Tide: Tide gages averaged Only applied in nested grids Elevation Data Point 13

14 Validation Results: 2009 Wave Height (m) Obs Model 0 12/9/09 12:00 12/10/09 0:00 12/10/09 12: validation Boundary Condition 14

15 Validation Results: 2007 Station H Observed H Modeled Assessment Close Close Close Close Close Low 15

16 Uncertainty: Wave Direction 2007 Storm: all within 0.4 meters 15 Degrees Plus 10 Degrees Plus 5 Degrees Plus No adjustment 5 Degrees Minus 10 Degrees Minus 15 Degrees Minus Observed Modeled

17 1-Percent-Annual-Chance Event Model validated successfully Define 1-percent-annualchance conditions Tide from 2012 New England Tide Report Wind from Buoy time history ( ) Wave height from Buoy time history ( ) 17

18 1-Percent-Annual-Chance Outer Boundary Waves Extremal analysis on data: 10.6 meters Direction in line with model grid Wind Extremal analysis on data: 25.1 m/s Direction in line with model grid Tide Applied per 2012 New England Tide Report (2.9 meters north, 3.1 meters south) 18

19 Next Steps Wave Heights at Transects Propagate onshore Wave setup/runup Mapping 19

20 Lessons Learned Flexibility in Approach Carefully Evaluate All BC/Validation Data sanity check Observations Model Results Consider spatial scales in approach 20

21 Questions? Project Team: Paula Kulis Nader Mahmoudpour Lauren Klonsky Brian Caufield Frannie Bui Ted Schultz Karen Kelley Paula Kulis