The objective of this task is to estimate storm surge and wave run-up characteristics for each of the prototype counties for each alternate water level scenario being studied. This information is required as input for the erosion processes modeling to estimate potential damages under differing water level regimes.

For historic conditions, measured surge levels have been derived by Baird through analysis of water level gage records. These have been interpolated to all 1 km reaches within the Flood and Erosion Prediction System. These analyses typically look at the maximum difference between an instantaneous reading at a particular gage and the monthly mean water level (stillwater) for the lake. For the alternative water level scenarios being developed, wave climate and storm surge predictions generated under other tasks will need to be applied to estimate frequencies and magnitudes of storm surges in the nearshore zone. Alternative surge scenarios can be automatically interpolated lakewide on a 1 km resolution with the newly developed system.

Wave runup characteristics are exceedingly site specific, since they are affected primarily by profile characteristics, substrates, and deepwater wave climate which vary considerably along he shoreline. Several studies have been conducted under the auspices of FEMA in the past on wave runup methodologies and coastal flood inundation probabilities. These studies are also being evaluated as to their detail, coverage, and utility for application for the wave runup prediction system that is proposed to being developed.

To date, the historic surge level data has been interpolated on a lakewide basis and has been estimated for selected study sites along the Lake Michigan shoreline. Baird has also developed time series of monthly vs hourly differential to convert future monthly data (the five scenarios) to hourly data for input to the erosion estimates and has developed a methodology for assessing coastal flooding in the five prototype counties. This methodology includes the following steps:

• Use estimates of wave height from COSMOS as input (or deepwater wave data calculated previously)
• Wave height input to runup model
• Predict runup and flooding elevation for future lake level scenarios in each county
• The extent of flooding and inundation are then mapped on DEMs for each county

Wave heights and storm surge/drawdown will be applied to random values of monthly means for each of the five water level scenarios. These datasets will be incorporated into the FEPS model. This analysis is complete for the five prototype counties, but must be performed for the remaining counties at a future date.

Click to return to the Lake Michigan Potential Damages Home Page.