Hurricane Harvey and the impact of sea level changes

Guest essay by Philip Lloyd

Hurricane Harvey broke the 12-year pause in Major tropical cyclones making landfall on the continental US. Inevitably, believers in Catastrophic Anthropogenic Global Warming [CAGW] had a celebration. They had correctly predicted climatic disaster. It mattered not that there had been earlier, stronger storms. Harvey was clearly the result of humans sinfully burning fossil fuels.

One of the problems with CAGW is the mistaken belief in an unchanged and unchangeable globe. Yet we know that on a macro scale, continents wander over the face of the earth and occasionally collide, throwing up huge mountain ranges. Around the Pacific, plates slide over the ocean floor, creating devastating earthquakes and chains of volcanoes. Glaciers grind away the slopes of high peaks, forming characteristic valleys. Rivers meander across the plains, shedding ox-bow lakes as they carve new passages. Nowhere does stasis rule.

Fixation is a poor guide to causation. Something struck me as I viewed aerial pictures of the floods as they poured off the land. Drainage was far slower than I had expected. Was something happening along the Gulf coast to alter the drainage? Much of it is low-lying. Was the sea-level rise of 2-3mm per year showing some effect?

I went to the tide gauge data (Permanent Service for Mean Sea Level, http://www.psmsl.org/data/obtaining/) There are 35 stations along the Gulf coast, of which 18 had more than 25 years of data and were reasonably complete. One station (Sabine Pass) had data until 1983, when it was moved about 3km and restarted in 1993. The datum evidently moved during the re-siting, but when 310mm was added to the post-1993 data, there was a consistent pattern with a low standard deviation, so an additional “station” using the combined data was used to fill in a wide gap between two other stations.

The location of the tide gauges is shown in Figure 1.

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Figure 1. Location of tide gauges (Google Earth). Freeport, to the west of Galveston, is not labeled

The data were downloaded as a .txt file and imported into Excel. Dates for which the data read -99999, indicating a missed reading, were deleted. The remaining data were analyzed using the Regression function in Excel, which yielded the standard deviation of the trend and an F statistic that was much less than 0.001 in every case. Figure 2 shows the data for PSMSL Station 161, Galveston Pier 21, for which there were nearly 1300 monthly readings, 99% complete from 1908 to 2017.

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Figure 2. Data for Galveston Pier 21.

The rate of rise was 6.41±0.10(std.dev.)mm per year. Note that the standard deviation is that of the trend, related to the more usual Pearson R by 1/√(n-1), where n is the number of monthly readings. There is a second station 2.8km south, at Galveston Pleasure Pier, PSMSL Station 828. Data is from 1958, but is only 89% complete. The rate of rise was 6.55±0.30mm per year. A T test showed that it was statistically identical to the Pier 21 data, giving high confidence in the reliability of the analysis.

The rate of rise is shown for all stations in Figure 3. In the east, the mean sea level averages the global average 2-3mm/year, which implies that the land is neither rising nor sinking. However, from Grand Isle at the mouth of the Mississippi west to Rockport, the rate of rise of sea level is 6-10mm/year. If the sea level is rising naturally at 2-3mm/year, then the land must be sinking at between 3 and 8mm/year.

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Figure 3. Sea level rise at stations along the Gulf coast

Over the course of a century, the mean sea level could approach 1m rise. The impact of this would not be insignificant, and should certainly be taken into account in planning any development in coastal regions. Focus on CAGW is global, and local issues such as abnormal sea-level rise are all too easily blamed on the global problem. All the hot air expended on rising carbon dioxide in the atmosphere will do nothing for a sinking Gulf coastline.

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39 thoughts on “Hurricane Harvey and the impact of sea level changes

  1. I’m not sure that anything will stop this stupidity. Elsewhere, I pointed out that models might predict stronger storms but 1-2 mph stronger winds with the warming so far. There was a link to an NOAA scientist and another to a quote of an IPCC lead author who said storms might 2-11% stronger by 2100. Then in a comment linking to a list of 30 publications that say there is no evidence that global warming has made hurricanes stronger I get asked for a link to the evidence. Its just getting too bizarre.

    • Your 30 publications must have all been by deniers. Papers written by deniers are not evidence. Only papers written by the faithful, peer-reviewed by the faithful, and published in a recognised Book of Climate Faith are true evidence.

      You’re right. It is getting too bizarre.

  2. The whole US coast from about Cape Cod south to the Rio Grande is sinking. That is obvious from even a quick look at a map. It has all the typical geomorphological characteristics:

    1. “Rias”, drowned river valleys, example: Delaware bay
    2. An extensive system of barrier islands
    3. Large “lagoons” inboard of barrier islands
    4. A striking absence of river deltas (the only exception being the huge Mississippi and even that has a very aberrant “crowfoot” structure).

    And an extremely flat carbonate platform such as Florida has virtually no natural drainage network. Typically drainage is underground in such areas, but with the current high interglacial sea level that is quite slow. It isn’t coincidental that most of Florida was a huge swamp until recent “development”.
    During glaciations Florida is more like Yucatan and a few million years ahead it will be like the Bahamas. A slightly higher and slightly lower carbonate platform respectively.

    • tty, right you are. And the entire west coast is rising, as shown by straight coast lines, higher benches of older kitchen middens (shown to me during geology field tours), lack of significant river deltas, and very limited reef development. This west coast rising is apparently due to plate collision/subduction and resulting thermal inflation. This thermal inflation gets so intense at times that molten rock erupts out of the ground, something unknown along the east coast. All-in-all a normal large Plate evolution.

      • I am not a plate tectonics scientist. I read with interest anything that pops up in the numerous news feeds I peruse, but that’s like assuming a medical degree because you’ve read a lot of Wikipedia articles. So, I have a question for you. Is the plate rigid enough that a rise in elevation on the west coast could be linked to a sinking on the east coast?

      • “Is the plate rigid enough that a rise in elevation on the west coast could be linked to a sinking on the east coast?”

        No. Only relatively small blocks (on the order of at most few hundred kilometers) ever behave as rigid bodies. Think of the crust more as rather thick layer of scum on top of very thick molasses. Where the molasses well up the scum rises, where the molasses go back down the scum sinks.

  3. Both the Mississippi and Nile deltas are not being replenished with the amount of silt as happened in the past as both rivers are heavily engineered. The Nile has the Aswan Dam which has stopped the annual flood and consequence silt deposition. The Mississippi has been heavily engineered to make it navigable to big ships and also prevent flooding. Therefore no or little deposition of silt is going to take place and land is being lost to the sea. This is not new knowledge. Also Florida has a subsidence issues because of water management that has favored land drainage while supplying water to large urban areas built on or close to wetlands. Again this is not new knowledge.

  4. Drainage was far slower than I had expected.

    A sea level rise of a few inches shouldn’t make that much difference to how fast the city drained … should it?

    Shouldn’t all the hard surfaces in a city speed up drainage?

    Is the answer that the land farther inland is draining through the city and thus increasing the amount of time the city is flooded?

    • commieBob September 15, 2017 at 3:40 am
      “Shouldn’t all the hard surfaces in a city speed up drainage?”
      Only to the point where the water leaves a roof or a road. The pipes that take water away can only take a finite volume of water whereas water on unmanaged land will spread out accordingly. In the UK just about all flood plain drainage is constrained by bridges, banked roads and buildings which makes water back up when there are floods. Some people don’t see that the clue is in the name; ‘flood plain’. We should be able to figure out how to live with water instead of ignoring old knowledge and resorting to litigation such as trying to sue Exxon for making it rain ‘more’.

    • In a large flat drainage area such as Houston, local developments will get the runoff very quickly from the roof or strip mall or other local development to the main drainage way. It will take on the order of an hour from the time it fall to the time it hits ground until it arrives at the main channel.The main channel however is very flat and will need time to drain. For a large city like Houston it would not surprise me if the main channel would take in excess of a week to drain for even the design storm, though that was greatly exceeded in this case. Regardless of what you do to the channel it will not flow very fast Where the sewers in the developments will flow at 3 ft/sec, the flow in the main channel will not get over 0.5 ft/sec in the best of times. So the channel will fill to the volume it needs to store however much stormwater there is: it will flood if not big enough. There will be culverts and bridges impeding the flow, but the main problem is that the slope of the channel is too flat. In this situation, a few inches at the coast will make no difference to the drainage from the city as a whole.

  5. ‘Anchoring Bias’ fed by ‘Confirmation Bias’ surrounded by ‘Group Think’…throw in fallacies of reasoning and argument including ad hominem personal attacks: “Deniers!”, begging the question: “everyone believes that cataclysmic climate change is real!” and appeal to authority: “the science is settled!”. The result, disastrous stupidity.

    • I see the History ( Propaganda ) Channel Directv 269 has the ” Two Degrees: The Point of No Return” intellectual masturbation 2hr masterpiece on tonight at 10:03-12:04 PM. I can’t watch such misinformed merde.(sarc) Can some body do an article for us to read about this travesty in and effort to spare us the anxiety? Thank you in advance.

  6. “Something struck me as I viewed aerial pictures of the floods as they poured off the land. Drainage was far slower than I had expected. Was something happening along the Gulf coast to alter the drainage? Much of it is low-lying. Was the sea-level rise of 2-3mm per year showing some effect?”

    A perfect example of starting off with confirmation bias.

    Drainage was far slower“; slower than what!? What metric are you applying here? From your description then immense leap to the sea, it appears your metric is opinion.

    Drainage is water flowing downslope. Flat slopes flow very slowly. Slow moving marshes, bayous and even main river flows are the norm along the gulf coast.

    No matter the alleged “sea level” claims, water on land flows from above sea level. That water is unaffected by sea level or tides until the descending water is joined to the sea; meaning at sea level.

    The Mississippi, Pearl and other rivers streams flowing into the gulf are all coastal plain rivers. Naturally, they flow very slowly and their paths meander. Until mankind decides to straighten and channel them, that is.

    These rivers often fall at a rate of fractions of an inch per mile. There is no comparison to higher elevation rivers, often termed freestone, that fall feet per mile.

    Inland Texas rivers and arroyos descend altitude rapidly and form dangerous water flows; until the water reaches flat land along most of the Gulf coast.

  7. Former House Speaker Tip O’Neil used to say “All politics is local”. The same can be said of apparent sea level rise.

  8. Most, if not all, of the land bordering the Gulf of Mexico is geologically unstable, and sinking. If one wishes to discuss the connection with AGW and sea level rise, tide gauge readings from somewhere like Honolulu would be much more appropriate.

    • The Hawaiian islands is anything but stable either. First they rise as they build on top of the hotspot, then as they move away from the hotspot they sink (and erode) as the weight of the volcanic pile presses down the seafloor. Finally they end up as seamounts thousands of feet below sea-level.

      If one wishes to discuss the connection with AGW and sea level rise, use tide gauge readings from a Precambrian shield somewhere well away (= a couple of thousand kilometers) from any existing or ice-age icecap. Examples: most of Australia, Brazil.

      But remember, no land is ever completely stable.

  9. It wasn’t clear from Chaamjamal’s comment (9/15 12:28) that he was talking about changes in the RATE of sea level rise, hypothetically caused by global warming. My essay considered only constant rates, which were different at different locations. There no evidence for any changes in the rate at a given location. He found likewise.

  10. I was one of the thousands flooded out of their homes by Harvey. The majority of flooding was not from coastal water, but from rivers and bayous greatly overflowing their banks. To make matters worse, lakes and reservoirs were opened up to keep them from overflowing which led to much greater flood damage down river. In my case, Lake Conroe was was opened up which led to at least a 1ft increase in the levels of the San Jacinto River. There has never been flooding where I live in the 35 years my family has been there, yet we ended up with 26″ of San Jacinto River in out house

  11. Google Earth has views of Galveston Bay bordering on Houston that start as early as 1944. They leave little doubt that the shoreline has retreated, in places by as much as 40m. It seems unlikely that withdrawal of fresh water would take place that close to the sea, so perhaps tectonics rather than human activity is the cause.

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