In some coastal cities, subsidence now exceeds absolute sea level rise up to a factor of ten

VOA A car tries to drive through Jakarta's flooded streets.jpg

January 2013 flood in Central Jakarta

There is a story in the Daily Mail cited by the GWPF which talks about subsidence due to groundwater extraction. For example, North Jakarta Indonesia has sunk four meters in the last 35 years, with other parts of the city also affected, and the impact of subsidence combined with heavy rain and high tides can be seen in the photo at right.

The gist of the study is that in some cities, subsidence is now exceeding sea level rise.

It is something to think about and cite the next time there is an alarming story about sea level “inundating” some city with a coastal flood.

Here are some excerpts and an abstract:

Forget global warming and melting polar caps – groundwater extraction is causing cities to SINK beneath sea level

  • Ground is dropping up to 10 times faster than the sea level is rising in coastal megacities, a new study says
  • Scientists at Deltares Research Institute in Utrecht studied subsidence in five coastal cities, including Jakarta, New Orleans and Bangkok
  • North Jakarta has sunk four metres in the last 35 years – a fall of 10 to 20cm per year and experts have called on governments to take action
  • Land subsidence is contributing to larger, longer and deeper floods
  • Total damage due to subsidence worldwide is estimated at billions of dollars a year and is set to increase

subsideence_coastal

I located the abstract for the research:

Sinking coastal cities

Dr. Gilles Erkens, Deltares | Utrecht University

G. Erkens, Deltares Research Institute, Utrecht, The Netherlands and Faculty of Geoscience, Utrecht University, Utrecht, The Netherlands, T. Bucx, Deltares Research Institute, Utrecht, The Netherlands

R. Dam, Deltares Research Institute, Utrecht, The Netherlands

G. de Lange, Deltares Research Institute, Utrecht, The Netherlands

J. Lambert Deltares Research Institute, Utrecht, The Netherlands

Abstract

In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. A major cause for severe land subsidence is excessive groundwater extraction related to rapid urbanization and population growth.  Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs. The total damage worldwide is estimated at billions of dollars annually. As subsidence is spatially different and can be caused by multiple processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes, how much is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

 

Geophysical Research Abstracts
Vol. 16, EGU2014-14606, 2014
EGU General Assembly 2014
© Author(s) 2014. CC Attribution 3.0 License.
Sinking coastal cities
Gilles Erkens (1,2), Tom Bucx (1), Rien Dam (1), Ger De Lange (1), and John Lambert (1)
(1) Deltares Research Institute, Utrecht, The Netherlands, (2) Faculty of Geosciences, Utrecht University, Physical Geography,
Utrecht, The Netherlands (g.erkens@geo.uu.nl)
In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without
action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level.
Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods
causing major economic damage and loss of lives. In addition, differential land movement causes significant eco-
nomic losses in the form of structural damage and high maintenance costs. This effects roads and transportation
networks, hydraulic infrastructure – such as river embankments, sluice gates, flood barriers and pumping stations
-, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annu-
ally.
Excessive groundwater extraction after rapid urbanization and population growth is the main cause of severe land
subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick
sequences of soft soil.
Because of ongoing urbanization and population growth in delta areas, in particular in coastal megacities, there is,
and will be, more economic development in subsidence-prone areas. The impacts of subsidence are further exacer-
bated by extreme weather events (short term) and rising sea levels (long term).Consequently, detrimental impacts
will increase in the near future, making it necessary to address subsidence related problems now.
Subsidence is an issue that involves many policy fields, complex technical aspects and governance embedment.
There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies
and measures that are effective and efficient on both the short and long term. Urban (ground)water management,
adaptive flood risk management and related spatial planning strategies are just examples of the options available.
A major rethink is needed to deal with the ‘hidden’ but urgent threat of subsidence.
As subsidence is spatially different and can be caused by multi processes, an assessment of subsidence in delta
cities needs to answer questions such as: what are the main causes, how much is the current subsidence rate and
what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas,
what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved
and responsible to act?
In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh
City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a
(generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.
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39 thoughts on “In some coastal cities, subsidence now exceeds absolute sea level rise up to a factor of ten

  1. I thought sea level increase was 2-3.3mm/yr for the past century. Where do they get 10?

  2. It’s a trade off…..there’s just as many tide gauges showing no sea level rise at all…or showing sea levels falling
    Like temperatures…it’s hard to find without adjustments

  3. Another good post zeroing in on New Orleans… http://pesn.com/2005/09/23/9600175_Rebuild_Energy_Systems_Not_NewOrleans/

    > The river is moving away from the city. The city is sinking
    > because of its weight, because no upbuilding by new muck
    > for many decades, because of being cut off from the fresh
    > water, because it is sliding off a cliff (the Continental Shelf),
    > and because the Oil and Gas Industry is extracting oil out
    > from under it. It is a city that for all intents and purposes
    > is now Sea domain. Spend the money on developing
    > alternative energy solutions instead.

    It goes into a lot of detail, including the history.

  4. Steve Keohane:

    From various orifices of their persons. There has not been such a rate as 10 mm/yr during the last eight thousand years or more, and probably never even at half that rate. In fact, there is presently no rise in SL, according to gauges on the Gulf coast (NOAA data)- the SL trend has been flat for the last sixteen years or so, according to these.

  5. how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act?
    ======
    reparations…..who do we sue

  6. There is another part of that subsidence equation that contributes to sea level rise. In 2010 sea level dropped by almost 7 mm and the heavy precipitation in Australia was considered the main cause. Such an explanation is definitely feasible because when more water stays on the land then less goes into the oceans. The same loss of ground water that now causes subsidence and sinking cities, quickly goes into the ocean adding to sea level rise. Likewise the degradation of 505 of our wetlands, and most of our rivers and streams has also caused much less water to remain on the land, and that lost water has contributed to rising sea levels.

  7. Good article on New Orleans – I have relatives there, visit it frequently. Most of south Louisiana is part of a sinking basin; that’s why the Mississippi flows there, after all. (water is gravity’s dog; it follows it everywhere) Before the great flood control projects started in the 1930’s (after the disastrous 1927 floods) the land remained in a rough balance – the basin would sink about 1/8 inch per year (but that’s a foot every 100 years), but the floods which came every spring deposited at least that much new soil in the area.

    Now the Army Corps of Engineers has put a stop to all that with the flood control systems, and a place with a lot of land that is only 2 or 3 feet above sea level is sinking at the rate of a foot a century. Not to difficult to see how that is going to turn out. Of course, the answer is just to tear down the levees and let it flood again each year like it used to, but the politicians don’t seem to like that idea much, either.

    One of the things discovered about draining swampland, which happened in a lot of the wards in N.O. which have never been rebuilt; once those places are dried out the soft soil beneath them compacts, and what you thought was going to be about sea level ends up being 10 – 15 feet below sea level, with big levees all around it. Not too difficult to predict what’s going to happen to those spots whenever the hurricane blows through.

  8. Small-scale subsidence has occurred due to ground water withdrawal while large-scale subsidence has been the result of petroleum extraction, the most spectacular examples being the Baldwin Hills dam collapse of 1963 and the sinking of the Long Beach Harbor by several meters, since alleviated through water injection. (Mayuga, M.N., Geology and Development of California’s Giant-Wilmington Oil Field, in Geology of Giant Petroleum Fields, Tulsa: American Association of Petroleum Geologists, Memoir 14, pp. 176-180, 1970)

  9. If the ground dips by 6 mm and the sea dips by 3mm then the sea rises by 3 mm relative to the ground. So which guages can be trusted to measure real sealevel rise due to anyeal increased volume of seawater?.

  10. Well d’uh. New Orleans…and Shanghai…are on deltas. The Mississippi Delta is the biggest sediment sink on the the North American Continent, and its rates of subsidence will easily outstrip any puny sea level changes. IT’S WHAT DELTAS DO. This comes as no surprise whatsoever. But try telling that to the Gristers, the ClimateProgressers, the SKS’ers, etc. Katrina’s effects were, and will remain, the product of AGW, in their books and propaganda.

    Tide gauges in Shanghai show the same thing…a rapid sea level rise. WRONG…….

    Man, the stupid hurts.

  11. University of Colorado global sea level rise data, easily accessible at climate4you.com, shows about 65 mm in the past 21 years, or about 3.1 mm per year; clearly not 10 mm/year.

  12. The SF Bay Area initially had no land below sea level but now it does (landward of the levees) due to ground water extraction and compaction of former wetland soils. Amazing thing about this is some of the affected areas are in tectonic uplift (although others – e.g. valley floors – are generally in subsiding basins).

  13. This is another reason (besides population growth) we’re going to have to adopt large scale desalination to supply fresh water in the future instead of extracting groundwater. Israel seems to be the leader in this technology — see here and here .

  14. @Alan Watt, Climate Denialist Level 7 says:
    May 1, 2014 at 10:09 am

    Desal was called for here in UK somewhere in the 70’s I think. Because it would be cheaper to do then than later…obviously, and clean water was required. Nope..it was totally ignored. I lived near the biggest Desal project in the world – Jeddah, Saudi Arabia, built approx 1981 by Consultants Weir Group Glasgow UK and a German Constructor (who else).

    Somebody told me sometime ago on a blog comment that if I wanted Desal water, each glass of would cost the same as that of a fine wine. It would indeed if the Gov run the project and take forever at massive cost overrun. Thats for known/old technology of course.

    In the Oman they suck the water so fast the plants die…from salt water ingression.

  15. Jakarta’s population comes in at about 10,000,000. Suburbanstats.org lists the population of The Big Easy as about 344,000. This is a mega-city??

  16. It is about time this aspect is getting some attention. I understand why they have left out subsidence. It confuses too many and muddles the message that CO2 is the one and only culprit. If this gets wide play, people are going to start asking questions. Just like natural variability. It gets way too messy having to explain those oscillations.

  17. .J. Hawkins says:
    May 1, 2014 at 10:37 am
    Jakarta’s population comes in at about 10,000,000. Suburbanstats.org lists the population of The Big Easy as about 344,000. This is a mega-city??

    It was, or at least moreso, before Katrina. Estimates are that over 1/2 of the residents have permanently left. The value is the proximity to those of us in the US as a nearby example that we can relate to more easily than Jakarta.

  18. > Jakarta’s population comes in at about 10,000,000.
    > Suburbanstats.org lists the population of The Big
    > Easy as about 344,000. This is a mega-city??

    Speaking of *SUBURBAN* stats, Wikipedia http://en.wikipedia.org/wiki/New_Orleans lists the 2013 population of “City and Parish of New Orleans” at 378,715. The Metro area (including the suburbs), is listed as 1,240,977. I don’t know if people outside of North America are familiar with the concept of suburbs.

  19. What’s Archimedes principle, Landrise and Land-sinking? And above all: How come so many never learnt what every 7th grader around the world is supposed to have been taught and learnt to understand?

  20. “James at 48 says:
    May 1, 2014 at 10:06 am”
    In Newark (CA), near the salt ponds, one subject that kept coming up was saltwater intrusion into the freshwater aquifers…not sure if this study addresses that, but continuing to draw down the water table will cause more problems than just (relative) sea level rise…

    Another reason to not dump fresh water into the ocean (in California)…

  21. About time somebody worldwide caught up with the going-down of the problem. Texas has mis-managed it in the past, but started regulating it as early as 1975!

    The 10 feet (>2500 millimeters!) of subsidence in Baytown is summarized below

    In fact, in the critical areas along Galveston Bay, the land surface has sunk as much as 10 feet since 1906! Experts have been studying the subsidence phenomena for almost 100 years, and with each hurricane we have weathered, we’ve seen subsidence and flooding problems worsen.

    One dramatic example of this was in the Brownwood subdivision, a coastal community of Baytown where almost continual flooding due to subsidence caused the area to eventually be abandoned.

    See also more plots:

    http://mapper.subsidence.org/

    from this web site, where additional maps and data are available.

    http://www.hgsubsidence.org/

    The Harris-Galveston Subsidence District is a special purpose district created by the Texas Legislature in 1975. The District was created to provide for the regulation of groundwater withdrawal throughout Harris and Galveston counties for the purpose of preventing land subsidence, which leads to increased flooding. The District’s enabling legislation is found in Chapter 8801 of the Special Districts Code.

    We achieve our goals through a combination of efforts. Of great importance is controlling subsidence by managing how we use our groundwater resources. This is accomplished through the careful regulation of groundwater withdrawals, working in collaboration with surface water suppliers. And just as significant – short-term and long-term – is the teaching and implementation of water conservation throughout our communities, neighborhoods, businesses, and households…all the way down to the youngest family members.

    We are frequently asked, “What, exactly, is subsidence and how are groundwater resources managed? And how do we successfully teach our water users to conserve?”

    Let’s start with subsidence. Webster’s defines it as “to sink, to fall to the bottom; to settle.” Well, that’s exactly what some of the land in our area has been doing since the 1920’s. Prior to World War II, areas with significant industrial and petrochemical development, such as Baytown and Texas City, experienced significant, localized subsidence. This trend continued during and after World War II, when rapid industrial and municipal growth began to create broad, regional patterns of subsidence, raising serious concerns over flooding.

    In fact, in the critical areas along Galveston Bay, the land surface has sunk as much as 10 feet since 1906! Experts have been studying the subsidence phenomena for almost 100 years, and with each hurricane we have weathered, we’ve seen subsidence and flooding problems worsen.

    One dramatic example of this was in the Brownwood subdivision, a coastal community of Baytown where almost continual flooding due to subsidence caused the area to eventually be abandoned.

    In 1975, as a result of area residents and local governments becoming increasingly alarmed by the continued impact of subsidence on economic growth and quality of life in the region, the Harris-Galveston Coastal Subsidence District was created by the 64th Texas Legislature as an underground water conservation district. Our main role at that time was to provide for the regulation of the withdrawal of groundwater to control subsidence. The challenge had begun. In that first year, we diligently gathered information on the Chicot and Evangeline aquifers. We analyzed planning information to learn more about water usage and water supply within our boundaries, and we began implementing regulatory procedures that led to our first groundwater regulatory plan

  22. Large as it may be I don’t think I would consider New Orleans a ‘mega city’.

  23. Withdrawing groundwater in countries that receive bountiful rainfall is a non-starter for subsidence. The WEIGHT of the city is enough of an explanatory factor. Indeed, this alone would express the groundwater out into the sea all by itself. New Orleans is built on saturated clays. The Mississippi itself would supply more water for recharge than needed if this was an issue there (I don’t believe it is).

    Now a bit of soil mechanics: If it is simply compaction, the subsidence rate slows over time and eventually the compacting layers would hold up the city at a certain point. And now water balance: 20cm per year subsidence would be ~120million m^3 of water withdrawn using just the city area. Rainfall on the city area is 2000mm (2 metres – 10 times the amount alledgedly used) and recharge availability for aquifers would actually be many times this since recharge is drawn from the entire watershed. It seems to me that they would have adequate rainfall for most of their uses. Now lets see about this.

    http://en.wikipedia.org/wiki/Water_supply_and_sanitation_in_Indonesia

    “For example, the main water source for Jakarta is the Jatiluhur Dam on the Citarum River 70 km southeast of the city. For those who are self-supplied (GP: largely outside of Jakarta) or receive water from community-based organizations, SHALLOW groundwater and springs are by far the main sources of water on most islands. On Sumatra and Irian, however, rainwater harvesting is also an important water source.[8]”

    In my experience, people who get adequate rain know how to quench their thirst.

  24. Thinking a little outside the square here, the Dutch are the ultimate in dyke building and flood defences. It was they that originally set up Jakarta, they were called back to their original work by Indonesia only a couple of years ago. The original drainage channels were full of rubbish, dumped cars etc.

    This article no doubt true to a large degree, could be a clever way for the Dutch to gain some serious infrastructure work in many places. Just saying.

  25. It is something to think about and cite the next time there is an alarming story about sea level “inundating” some city with a coastal flood.

    There are also other things to think about regarding sea level rise and inundation.
    Groundwater abstraction contributing to 1/4 of sea level rise and atoll island degradation.

  26. and not one word about sedimentation…
    How ridiculous to claim the rain in Australia…
    …and think this doesn’t add to sea levels

  27. Jakarta isn’t just sinking, the local bureaucracies are AWOL. Every year it floods, every year people clamour about doing something about it, and every year nobody does anything. Streams flow from the hills which are cleared of vegetation with no dams or sluices or proper water management, and the areas downstream clog up with rubbish, silt, and over-development. its stormwater runoff from over-development and clogged waterways without supervision. The water that comes down gets trapped and floods as much by water mismanagement as it does by sinking ground.

  28. This has been known for some years and, if memory serves, it’s mostly due to ground water removal and large scale building construction in areas where ground water has been removed. But you never get to hear that. It’s all due to CO2.

  29. Blaming ground water removal for land sink is spurious. First ground water is found in the interparticle spaces and cracks in the rocks. Removing the water will not cause the voids to close.
    Djakarta is on a very volcanically active plate boundary so my first choice for the cause would be volcanic, some underground magma movement.

  30. John Marshall:
    That is what I thought, but I have learned different. The susidence in the vicinity of Galveston Bay is due to groundwater removal from aquifers that have shale and sand interfingering and apparently water is expressed from shales into the sand as water is extracted by wells. This leads to compression of the shales, according to the volume of water expressed.

  31. Posted about this before on another thread.

    The subsiding Big Easy has been going on for 60 years or more. Grew up there and saw it.

    The delta does not flood much anymore due to levees and the diversion of the Big Muddy using the Old River project up the river, which diverts a significant amount of water to the west.

    The hydrostatic pressure under NOLA has been going down for all that period. My uncle’s home built in the early 50’s had the concrete slab exposed by 1980 or so. The ground was sinking. There are also pictures of street signs and such from south of NOLA that show the subsiding soil.

    As far back as the late 1950’s the river becme “tidal” (SP?). The level at Jackson Square would rise and lower. Didn’t quite back up, but it was clear that it was not like 100 years before we built all the levees the Corps built and the canals used by the oil companies.

  32. Pozzuoli, a few miles west of Naples (Italy), sits inside an old but active caldera, Campi Flegri. The town of Pozzuoli rose some 6m a few years ago. The authorities expected an active vent to open. Luckily the land subsided some months later. This was due to magma movement within the magma chamber below the town. Roman ruins in the town are evidence of past upheavels.

  33. Looking at this from a layman’s point of view, the draw down of water coupled with the weight added and the motion of traffic above is causing settling of the earth, As we draw down the water each year from the aquifers during summer and it rebuilds in winter it is the weight and motion on the surface which causes liquefaction of the underlying soils. This liquified soil then migrates into cracks and crevasses slowly but surely compacting.

    Add to this natural earth quake activity along with stress of the earths surface caused by Continental twisting, pressures created by earths rotation and the earths mantle of liquid rock you simply have the natural cycle of earths crust forming, deforming, and regeneration.

    Much like the glaciers which caused whole continents to subside mans pointed increase of weight in cities is a natural compactor. The answer then is to spread out that weight and water consumption over larger areas to slow this process down.

    This will not go over well with the enviro-wackos and Agenda 21 folks who want to compact people into cities and limit their movements while leaving huge swaths of land untouched and unused.

  34. The drawing down, as Bill H posts above, is called compaction, an interaction of water and gravity on the particles. With compaction comes dewatering, when the weight of compacted rock particles closes voids and extrudes water. These processes lead to sinking like the coastal region of Bangladesh, part of the worlds largest alluvial fan. Liquifaction is a different process due to agitation of water saturated loose particles like sand and is often caused by earthquakes. Even walking over such ground can cause liquifaction and the walker trapped.

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