The objective of this task is to apply a nearshore wave transformation procedure to determine local wave condition input to the erosion processes model using the deepwater WIS data for various scenarios as input. In many open coast locations this transformation procedure will be straightforward and will incorporate application of the TMA spectral similarity concept in addition to linear wave refraction. However, at some locations (particularly for the lakewide application) more detailed estimates of wave conditions may be required (e.g. for sheltered bays or areas inshore of shoals or islands). Owing to the size of the lake, the simplest possible techniques will be applied to address these complexities. The work conducted under this task is essential to develop input for the erosion processes modeling associated with the detailed study sites investigations and the lakewide applications.

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

Estimates have now been made for each of the 5 prototype counties.

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