From The Conversation, stuff that people do and have done, to and with the natural and built environment (whoo, that a sentence), October 16:
Coastal cities have a hidden vulnerability to storm-surge and tidal flooding − entirely caused by humans
Centuries ago, estuaries around the world were teeming with birds and turbulent with schools of fish, their marshlands and endless tracts of channels melting into the gray-blue horizon.
Fast-forward to today, and in estuaries such as New York Harbor, San Francisco Bay and Miami’s Biscayne Bay – areas where rivers meet the sea – 80% to 90% of this habitat has been built over.
The result has been the environmental collapse of estuary habitats and the loss of buffer zones that helped protect cities from storm surge and sea-level rise. But the damage isn’t just what’s visible on land.
Below the surface of many of the remaining waterways, another form of urbanization has been slowly increasing the vulnerability of coastlines to extreme storms and sea-level rise: Vast dredging and engineering projects have more than doubled the depths of shipping channels since the 19th century.
Some of these oceanic highways enable huge container ships, with drafts of 50 feet below the waterline and lengths of nearly a quarter mile, to glide into formerly shallow areas. An example is New Jersey’s Newark Bay, which was as little as 10 feet (3 meters) deep in the 1840s but is 50 feet (15 meters) deep today.
A consequence of dredging deep channels is that water also enters and exits the estuaries more easily with each tide or storm. In these dredged channels, the natural resistance to flow created by a rough and shallow channel bottom is reduced. With less friction, that can lead to larger high tides and storm surge.
As coastal engineers and oceanographers, we study coastal ocean physics and storm surge. There are solutions to the problems “estuary urbanization” is causing, if people are willing to accept some trade-offs.
An unintended side effect of dredging
The effects of dredging are most visible in the daily tides, which have grown larger over the past century in many estuaries and aggravated nuisance flooding in many cities, as our research shows....
....MUCH MORE
The places here the water meets the land and where the water meets the atmosphere are home to some of the most complex phenomena on earth. From a 2019 post "World Class Fisheries: Our Friend The Cod (and an amazing bit of research)"
Starting about fifteen years ago there were signs that Atlantic cod were heading north and invading the territory of their polar cousins, which may, or may not, be a harbinger of changes brought about by anthropogenic global warming.
The attribution studies are still too simplistic, compared to the systems they are trying to correlate, to be of much use to policy makers.
If done correctly, the interactions in this kind of study, between the atmosphere, sea-surface, deep sea and biology become mind-boggling very shortly after you turn your supercomputer on.One, just one factor that goes into figuring out what is going on, turbulence, is called the "oldest unsolved problem in physics" and it is but one factor in the complex-chaotic systems - and their interactions - that you are trying to understand. We'll have more on that after the jump....****....And back to turbulence.From the Presentation Speech by Professor Stig Lundqvist of the Royal Academy of Sciences for the 1982 Nobel Prize in Physics
Your Majesties, Your Royal Highnesses, Ladies and Gentlemen,
The development in physics is on the whole characterized by a close interaction between experiment and theory. New experimental discoveries lead often rapidly to the development of theoretical ideas and methods that predict new phenomena and thereby stimulate further important experimental progress. This close interaction between theory and experiment keeps the frontiers of physics moving forward very rapidly.
However, there have been a few important exceptions, where the experimental facts have been well known for a long time but where the fundamental theoretical understanding has been lacking and where the early theoretical models have been incomplete or even seriously in error.
I mention here three classical examples from the physics of the twentieth century, namely superconductivity, critical phenomena and turbulence. Superconductivity was discovered in the beginning of this century, but in spite of great theoretical efforts by many famous physicists, it took about fifty years until a satisfactory theory was developed. The theory of superconductivity was awarded the Nobel Prize in physics exactly ten years ago. The critical phenomena occur at phase transitions, for example between liquid and gas. These phenomena were known even before the turn of the century, and some simple but incomplete theoretical models were developed at an early stage.
In spite of considerable theoretical efforts over many decades, one had to wait until the early seventies for the solution. The problem was solved in an elegant and profound way by Kenneth Wilson, who developed the theory which has been awarded this year’s Nobel Prize in physics.
The third classical problem I mentioned, namely turbulence, has not yet been solved, and remains a challenge for the theoretical physicists....
As I said, mind-boggling.note: If you are good at such things the Clay Mathematics Institute made the Navier-Stokes equations one of their Millennium Prize problems, solve it and pocket a million bucks:
More to come re: Fish on the move, previously, (proto) Fish on the Move: "The world’s fisheries are incredibly intertwined, thanks to baby fish".
Prove or give a counter-example of the following statement:
In three space dimensions and time, given an initial velocity field, there exists a vector velocity and a scalar pressure field, which are both smooth and globally defined, that solve the Navier–Stokes equations.
Details here.
Followed by "Think You're Smart Don'tcha: Figure This Out And Make A Million Bucks" in 2021:
In last week's post "Fluid Dynamics (and the filth on your phone)" I made the assertion "This is one of those fields of study that are so mind-bogglingly complex that....", without supplying any supporting statements or facts.(in these situations the reader can assume I am relying on the Charlie Munger all-purpose turnaround: "Think about it a little more and you will agree with me because you're smart and I'm right.")But for folks who require a bit of backup, here is Ars Technica, followed by the Clay Mathematics Institute, along with a cameo by Feynmann for added "Appeal to Authority":...