ROMS wetting/drying inundation/storm-surge simulations

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lanerolle
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ROMS wetting/drying inundation/storm-surge simulations

#1 Post by lanerolle » Thu Apr 22, 2010 8:19 pm

Has anyone applied ROMS to do inundation/storm-surge type wetting-drying simulations? I need to do such an application and I am wondering whether ROMS can accept negative depths (land) in addition to positive ones (water)?

Suppose I have an island in a tidal zone where the water depths vary from 0m to a depth say 100 m around it and where the island topography ranges from 0m (coincident with water/land interface) to say -10m (maximum land height on island). Then if I generate my permanent wet-dry mask at MHHW the depths above it will never wet and only the depths below it will dry and the wetting/drying in ROMS should work well. However, my depths from 0m (water/land interface) to MHHW will be negative and the depths below 0m will be positive. Can ROMS handle such a situation and will the Dcrit parameter in toms.in (set by default to 10 cm) discriminate between a wet and dry cell correctly?

jcwarner
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Re: ROMS wetting/drying inundation/storm-surge simulations

#2 Post by jcwarner » Fri Apr 23, 2010 1:32 am


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drews
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Re: ROMS wetting/drying inundation/storm-surge simulations

#3 Post by drews » Fri Apr 23, 2010 2:40 pm

MHHW is Mean Higher High Water:
http://tidesandcurrents.noaa.gov/mhhw.html

I use ROMS to study storm surge (wetting) and wind setdown (drying) in Egypt's Nile delta. I #define WET_DRY like John says, and use the default critical depth of 0.10 meters. I set my land/sea masking to 30 meters above sea level, which is well above any conceivable storm surge. My terrain has negative and positive depths. So anything in the delta can theoretically get flooded, but ROMS doesn't have to compute the highlands around Cairo and farther south. I used a grid resolution of 86 meters (3 arc-seconds). I would set your land/sea mask above MHHW, just in case some really big typhoon blows through.

This research was for my Master's thesis, if you want to read more:
http://gradworks.umi.com/14/68/1468999.html

The wetting/drying scheme in ROMS works like a charm! The only strange behavior I find is some "splatter"; fast-moving wind-driven blobs of water that scoot across flat dry land. These blobs are less than 11 centimeters deep (just over the critical depth), and they show up in the ROMS wetdry_mask_rho like this:

Image

Red is water. Wind is from the right. To get rid of the blobs, I masked out any water depth less than 0.11 meters during post-processing. If your shoreline is steep you probably won't have to worry about the splatter. :D

Here is a recent paper on using ROMS for modeling storm surge:
Wang S, McGrath R, Hanafin J, Lynch P, Semmler T, Nolan P (2008) The impact of climate change on storm surges over Irish waters. Ocean Modelling 25(2008), 83-94.

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