Calculating Port Dangers

Fig. 1 Shallowness dangers

When a seaport is located within a coastal area that is experiencing sea level fall, the shallowness danger increases as time goes on because the likelihood of ships  running aground constantly increases (Fig. 1):

"Dredging often is focused on maintaining or increasing the depth of navigation channels, anchorages, or berthing areas to ensure the safe passage of boats and ships. Vessels require a certain amount of water in order to float and not touch bottom. This water depth continues to increase over time as larger and larger ships are deployed. Since massive ships carry the bulk of the goods imported into the country, dredging plays a vital role in the nation's economy."

(National Ocean Service). This sea level change shallowness is in addition to the normal dredging requirements that can happen to any port, thus, the problem with sea level fall is that the dredging must continually go deeper and deeper into the land beneath the normal depth of normal maintenance dredging.

Fig. 2 Too-deep dangers

The problem is reversed when a seaport is located within a coastal area that is experiencing sea level rise, because the proper orientation of the unloading machinery to the ship cargo decreases (Fig. 2):

"Global warming can force large mean sea level changes, by the combination of: (i) ocean thermal expansion due to the increase of the ocean heat content; (ii) ocean water mass increases from the melting of the continental ice sheets, caps and glaciers; (iii) isostatic adjustment, anthropogenic coastal subsidence and changes in land water storage. Recent observations suggest a globally averaged mean sea level rise (SLR) of about  4.0 cm per decade (WMO, 2021). SLR projections are being continuously revised upwards, with recent projections suggesting that, by 2100, with 2°C of global warming above pre-industrial levels (specific Warming Level-SWL of 2°C), global SLR will be 30 - 93 cm higher than the mean of the 1986 - 2005 period (IPCC, 2018). Importantly, higher mean sea levels, combined with future extreme storm surges, waves and tides, could generate devastating extreme sea level (ESL) events, which pose a particular threat to seaports across the globe."

(UN Trade & Development). One thing that won't help is to hide our heads in the sand of time and 'hope' it doesn't matter (it really does matter).

You can acquire more information about each coastal location  ("Coast Id") at this link (Obtaining Tide Gauge Data).

Closing Comments

I am doing some research and preparing to do posts that show the date in history that various ports were built, remodeled, and/or moved.

This is being done so that a sharper awareness can be developed as to what dangers are worse to a particular port so that port authorities can make timely responses.

But let's remember that we don't know exactly what degree of acceleration is in the works at the various Cryosphere locations (a bit of 'over reacting' is not as bad as underestimating).

Today's appendices are a few examples of the kind of sea level change (fall or rise) that different countries have, are, and or will experience (Appendices: A-F, G-L, M-R, and S-Z). 

They are all coastal areas that have one or more ports.

These appendices have graph lines colored blue, green, and brown like Fig. 1 and Fig. 2.

The blue line represents estimated historical levels prior to the time when tide gauge station measurements began, the green line represents in situ (actual) measurements by tide gauges, and the brown line represents future estimations out to the year 2050 beyond the actual measurements that have been recorded.

Note that on the right-hand side of the appendix graphs each line color area has an estimate of its sea level change (SLC) as a portion of the whole quantity which is also shown.

The Dredd Blog seaport series (Seaports With Sea Level Change, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35) has a lot of info but does not consider when ports were constructed and therefore how much time is or is not on their side.

The next post in this series is here.