Great Lakes Dredge & Dock Corp. Form 10-K (Annual Report) Filed 03 06 15 For The: Fill & Download for Free

a couple things come to mind pretty quickly.I’ve written several other answers related to the issue of minimum depth under the keel for submerged operations… Nearly every river in the world is too shallow to operate a warship submarine submerged…. even the ones that boast the deepest water in the world are only that deep for very small areas. For example, the Hudson River which claims 200 ft deep is only that deep in an area of the Hudson Highlands region called ‘World’s End’ and that deep ravine is about 2 acres in size.. most of the rest of the river is shallower than the ocean channel the Corps of Engineers dredges to 35 ft for shipping.Secondly, even a WWII U-boat was about 50 ft tall from periscope top to keel… same approximate height of all WWII navies and actually all modern submarines today whether they are nuclear or AIP…. Nuclear ships have much more volume but all ships are around the same height ( within 10–15 ft)Understand regarding the Great Lakes - the entirety of Lake Erie is less than 200 ft deep and nearly 50% is less than 60 ft deep… It is a very shallow lake and impossible to navigate during wartime at periscope depth without detection… See Chart 14820 below. all of the area outside the red line is shallower the 97 ft. all of the area outside the blue line is shallower than 65 ft. ( lines are approximate- added by author). The deepest area in the entire southern half of the lake in merely 78 ft deep. This is much too shallow to operate a WWII DE sub.You can play this game yourself - NOAA Nautical Charts - Great LakesFurther, there are locks, canals, and rivers that must be used to reach the upper Great Lakes because you know there’s the Niagara Waterfall….

Here is a bathymetric map showing the depths of each Great Lake:Lake Superior- Is the Largest and Deepest Great Lake. It has an Average Depth of 483 ft (147 m) deep. Lake Superior's Deepest Point is 1,333 ft (406 m) deep! Here is a video of a research team sending a probe down to one of the Deepest Points of Lake Superior:Lake Michigan- (The Great Lake I live the closest to) has an Average Depth of 279 ft (85 m) deep. Meanwhile it's Deepest Point is 925 ft (282 m) deep.Lake Huron- has a Average Depth of 195 ft (59 m) deep. Huron's Deepest Point is 748 ft (228 m) deep. However interestingly Lake Michigan and Huron are actually technically one lake!Lake Erie- Is the Shallowest Great Lake. It has an Average Depth of 62 ft (19 m) deep. It's Deepest Point is 210 ft (64 m) deep.Lake Ontario- has an Average Depth of 283 ft (86 m) deep. Meanwhile Lake Ontario's Deepest Point is 804 ft (245 m) deep.Although it's not one of the major Great Lakes, it's still technically part of the Great Lakes system, Lake St. Clair (which is right by Detroit) depth is pretty interesting. It is very shallow and has a Average Depth of 11 ft (3.4 m) deep! It's Deepest Natural Point is 21.3 feet (6.5 m) deep, however there is a man-made channel in the lake that is 27 feet (8.2 m) deep and was dredged in order to allow big lake freighters to navigate through easily.Lastly here is a pretty cool map that shows and compares the Depths and Distances of The Great Lakes:

The main issue will be the loss of coastal areas. They will just become too expensive to maintain and replace.Even before climate change was confirmed, most beach areas required “renourishment” which is a fancy word for “dredging sand from the seabed to add to the beach”. In some areas, like river deltas, this happens naturally. In addition, sometimes erosion from one area piles up in another. For example, there are several sandbars in the Great Lakes that are the result of erosion elsewhere.But as water levels rise, even slightly, the erosion becomes much quicker. Areas that do regular nourishment are noticing this already - you have to do it much more frequently. However, renourishment isn’t cheap. The problem is, if you don’t do it, everything you build on the coast falls into the sea.And lots and lots of cities worldwide are at or just above sea level. In the U.S. alone you have New York, Washington D.C., Miami and New Orleans.This renourishment in Miami Beach took 300,000 tons of sand and cost $11.5 million. However, it’s only temporary.But one bad storm can do a lot of damage quickly.This is Rockaway Beach, New York City, after Superstorm Sandy. Other low lying areas of New York City and nearby New Jersey were similarly affected, as was Atlantic City and the Jersey Shore, which is similarly just above sea level.Now, people are resilient and will often try to rebuild after a disaster. However, it always requires a lot of money. New Orleans was rebuilt after Hurricane Katrina, but still lost a lot of homes and people permanently.And it’s not just big cities. The Atlantic Coast of the United States is lined with are what are called “barrier islands” that are little more than sandbars with vegetation. Even the big ones, like Long Island, New York, are generally low lying. However, they range from places that are “just getting by” to high end resorts. It doesn’t take much of a rise in sea level to take a lot of land off the edges of these.