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Gibraltar Strait Dam: History of a Sea-change Macroproject Proposal
Note: An expanded and updated version of this report is now available here
Richard Brook Cathcart
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Abstract
Herman Sorgel (1885-1952) organized a pan-European effort existing from 1929 to R&D Atlantropa Project, a macroproject intended to reduce the Mediterranean Sea's area by 30% by artificial closure of the Strait of Gibraltar allowing natural evaporation to diminish the Sea's bulk, exposing new land (former continental shelf). Sorgel sought to control North Atlantic Ocean seawater inflow to generate electricity. By 1997, R. G. Johnson postulated erection of a partial dam at Gibraltar Strait to control the outflow of seawater from the Mediterranean Sea without generating electricity. Some of the facts, assumptions and prognostications related to both of these visionary macro-engineering ideas are examined historically.
Introduction
Completed hydroelectric dam macroproject proposals focused on the Persian Gulf at the Strait of Hormuz (Schuiling, 2005) and on the Red Sea at Bab-el-Mandeb (Schuiling, in press) increase the possibility that an old macroproject for the emplacement of some type of Strait of Gibraltar hydraulic barrier that throttles seawater flows (inflow and outflow) in the Strait of Gibraltar will be revived during the 21st century. Macro-engineering’s fixation on the Strait of Gibraltar is centered on proposals to span it with a bridge – perhaps as blueprinted by T. Y. Lin (1912-2003) – or a tunnel to function as a Europe-Africa permanent transportation linkage across the Strait of Gibraltar (Starossek, 1996). The first physical link between Europe and Africa was formed late in the 20th century by the 400-kV electrical cable serving Morocco and Spain (Anon., 1999).
About 33% of the world's humans live within 100 vertical meters of present-day sea level (Small and Nicholls, 2003). An expected future rise in the global sea level, which will inevitably influence the Mediterranean Sea Basin's natural 13,000 km shoreline, has instilled reasonable trepidation in Italy's public that is reflected in the continuing debate about the macro-engineering appropriateness of Venice's protection against seasonal high-tide/storm surge seawater flooding by a costly lift-gated permanent dam (Nosengo, 2003). Worldwide, approximately 10 million persons today live below contemporary sea level; as the world's sea level rises during the 21st century, more people may be fated to do so also as, for example, in the Mediterranean Sea Basin (Perissoratis and Georgas, 1994).
Historians of technology recently reviewed the old macroproject proposal known finally as the "Atlantropa Project", but with no aim to revive it, merely to note its proper place in the centuries long unfulfilled experience of Europe's economic and social integration (Trischler and Weinberger, 2005). The ongoing shift in the Mediterranean Sea Basin's human population demography seems to point to a new, favoring regional public attitude on the increasing practicality and imperative necessity of a revamped "Atlantropa Project"!
During April-September 2003 the Deutsches Museum in Munich, FRG, exhibited "Klima: das Experiment mit dem Planeten Erde". By displaying the inspiring drawings of the envisioned facilities planned for the Gibraltar Strait Dam and the empoldered Mediterranean Sea (Voigt, 1998; Gall, 1998) the public was informed of Macro-engineering's recounted history. In 1929, the impresario Herman Sorgel (1885-1952) first detailed a concrete gravity dam to adjustably control the seawater inflow through the seaway connecting the North Atlantic Ocean and the Mediterranean Sea (Spiering, 2002). The hydroelectric dam in the Strait of Gibraltar was the main infrastructure facility that would unleash chiefly European farm and city reclamation of the exposed continental shelf that would soon appear because closure of the Mediterranean Sea Basin can cause a natural evaporative reduction of the sea. (Dams proposed for the Red Sea and the Persian Gulf are justified similarly.) Seawater coming from the Black Sea (with a Dardanelle sill depth of 70 m) and the Suez Canal will still find entrance to the Mediterranean Sea, although such seawater flows must be entirely controlled by dams and sea locks if massive hydraulic erosion is not to take place.
Herman Sorgel, and many other persons then and later, imagined the creation of additional European colonies in Africa; Greater Europe was to extend from the North Pole to southern Africa (O'Loughlin and Wusten, 1990). Until the 1950s, Europeans continually pursued a geopolitical and geoeconomic union with northern Africa (Muller, 2000). In 1950, the population of the Mediterranean Sea Basin was 170 million Europeans (73%) and 63 million North Africans (27%); by 2025, there could be 305 million Europeans (44%) and 381 million North Africans (56%). World War II casualties in Europe, post-World War II Muslim immigrants to France from Algeria and Germany's 1950s Muslim guest-worker program, together with high birthrates amongst European Muslims and low birthrates amongst traditional Europeans are the chief causes of the remarkable demographic shift. The African Union was proclaimed on 1 March 2001 and on 29 October 2004 Europe’s leaders signed a European Union Constitution. During 2005, however, voters in the Netherlands and in France failed to approve the proposed Constitution, making the tentative Constitution inoperative politically.
Currently, a demographic shift in Europe seems to presage an epoch – occurring, perhaps, sometime around 2010-2050 – that will forever alter Europe's still distinctive culture: post-World War II Europe has been colonized by Muslims from Africa. By 2010-2050, Muslim's in southern Europe (Spain, France, and Italy) may form ~25% of the total population and working Muslim adults may total ~40% of the available labor force. This means that an almost forgotten macroproject such as the Gibraltar Strait Dam and its associated infrastructure developments may find future acceptance amongst voting citizens of southern Europe and northern Africa. Forecast future climate regimes in the Mediterranean Sea Basin are likely to be the initial stimulation for a rethinking of the old macroproject proposal.
The Netherlands owns infrastructure worth approximately $2.5 trillion that has been emplaced to protect the people of that country from unwanted seawater incursions. There appears to be a 1% chance that a 1 m rise in global sea level will come to pass during the 21st century. To safeguard the 13,000 km-long coastline of the Mediterranean Sea Basin from incursive future sea level rise – figuring $1 million per linear kilometer – almost $13 trillion would have to be expended for total protection! Of course, that is an excessive cost, quite unlikely to ever be considered anything other than ultimate limitation. Since "miscalculation or sheer ignorance of cost and difficulties was the key to launching a number of great and successful enterprises, from canals and railroads to mining and manufacturing" (Sawyer, 1952), it might seem best, even wise, to glibly gloss over the Gibraltar Strait Dam’s dangers and difficulties in public media so that modern-day macroengineers can be inspiring and calm, reassured by displayable positive cost/benefit analyses, attractive detailed construction blueprints and privately adjustable building timetables! Nevertheless, some of the details of this macroproject are revealed below. The optimal style of a dam building is specific to the particular macroproject, the nature of the geophysical work site as well as social uncertainty, the undertaking management organization’s experience, the operational complexities of many kinds of construction machinery and worker nationalities, the macroproject's situational geography and the logistics of required materials.
The Mediterranean Sea
Kenneth Jinghwa Hsu's The Mediterranean Was a Desert (1983) popularized the geological theory of the total desiccation of a closed off Mediterranean Sea – when the Strait of Gibraltar did not exist – that may have occurred more than 5.3 million years ago when virtually all seawater evaporated to form an arid saltpan valley several kilometers deep. The validity of Hsu's geological theory remains in question (Hardie and Lowenstein, 2004). Today's Strait of Gibraltar is a shallow (320 m deep) and narrow channel (13 km wide) and it is the Mediterranean Sea's only natural connection with the North Atlantic Ocean. The Mediterranean Sea's area (about 2.5 × 1012 m2) amounts to about 0.7% of the surface of the world-ocean's surface and about 0.3% its volume. The below-sea level region, ranging in depth from 0 to 200 m, comprising the continental shelf is 30% of the (sea floor) area. Supposing the Strait of Gibraltar to be closed, the present-day rate of sea level depression caused by normal evaporation from the Mediterranean Sea could be about 0.5 m/yr; uncovering the continental shelf to add new land to humanity's resources base would require a wait of nearly four centuries. Were climatic conditions in the Mediterranean Sea Basin to change drastically, the rate of depression would also change impressively (Sanchez, 2004). The temperature of the surface layer of seawater is an important physical property that influences the transfer of heat energy, momentum, water vapor and gases between the sea and the air. River discharge changes caused by climate change also will affect the Mediterranean Sea's rate of depression owing to evaporation (Struglia, 2004). Most of the airborne moisture leaving the Mediterranean Sea Basin later descends as precipitation onto western Russia and northern Europe. A rise of sea level within the Basin will directly impact all transshipment gateway seaports – commercial shipping harbors with supporting hinterlands that are rich in industrial and agricultural production and consumption – such as Port Said, Damietta, Marsaxllok, Gioia Tauro, Algeciras: a sea level rise will deepen all harbors while a fall would make all harbors shallower. Trade within the Mediterranean Sea, served by ports such as Barcelona, Marseilles, Genoa, Piraeus and Izmir will also be affected by any future changes of harbor navigation depths.
Gibraltar Strait Dam
Macro-engineering's elite has considered a linkage of Europe (Spain) and Africa (Morocco) by railroad tunnel or automotive vehicle-carrying bridge (Lin and Chow, 1991). On 24 October 1980 the "Treaty of Spanish-Moroccan Cooperation to Build a Fixed Link Between Spain and Morocco" was signed; a decision by Spain and Morocco whether to start digging a long and deep tunnel will be announced during 2008. A tunnel is a linear macroproject that has unique problems in subterranean ingress and egress as well as material logistics and the daunting potential for life-threatening macro-problems such as unstable rock, high ground water pressure in undersea tunnels, equipment fires, gas intrusions and gas explosions. The myth of Atlantis, as well as the history of the 1755 Lisbon, Portugal earthquake and tsunamis, indicate other hazards affecting any macroproject, whether bridge, tunnel or dam, put into the Strait of Gibraltar (Gutscher, 2005). Earthquake-rocked Japan's undersea Seikan Tunnel connecting Hokkaido and Honshu islands by railroad has operated safely since the late 1980s, but it took decades to excavate and went far over its planned construction budget.
First advanced as a plan to control the flow of the North Atlantic Ocean's surface layer waters into the Mediterranean Sea for the purpose of hydroelectric production and grand-scale continental shelf land reclamation for settlement, after World War II the Atlantropa Project was publicly touted by two technology historians, separated by a demographic generation, as a "macroproject of the future". Walter H. G. Armytage (1961) and Ervan Garrison (1991) voiced their professional convictions in popular books that a Strait of Gibraltar Dam generating electricity was very desirable, potentially a key piece of world civilization's infrastructure. Nevertheless, and in marked contrast, Stephen H. Schneider has alluded to this old Mediterranean Sea Basin reclamation macroproject plan. But, Schneider goofed – he jumbled all the germane geographical facts (Schneider, 1996). A Herman Sorgel-planned Gibraltar Strait Dam would never cause the Mediterranean Sea's level to rise, raising the ridiculous possibility of enlarging northern Africa's Lake Chad via a "Second Nile River" dug to carry salt water overflow from the Mediterranean Sea! Schneider also claimed that Sorgel's dam could degrade northern Europe's climate owing to the stoppage of the saline seawater outflow from the Mediterranean Sea into the North Atlantic Ocean.
Late in the 20th century, Robert Glenn Johnson, suspecting that the increasing salinity of the seawater exiting the Mediterranean Sea at the Strait of Gibraltar might be the near-term future cause of a new Earth ice age – predicted onset in 30 years – proffered a controversial proposal to study the macro-engineering concept of a porous barrier, a permeable rubble-mound dam, emplaced in the fluid connection between the North Atlantic Ocean and the Mediterranean Sea (Johnson, 1997). Johnson's rubble pile seawater flow throttle was only intended to slow the outflow of highly saline water, which eventually affects the essential physical characteristics of seawater in the North Atlantic Ocean, in order to prevent ice sheet formation in northeastern Canada. His anti-ice age macroproject rests entirely on the proposition that Egypt's Aswan High Dam (closed in 1965) has caused the measured increased salinification of exiting Mediterranean Sea water; Johnson's rubble dam – really an anthropogenic submarine ridge – proposal becomes an expensive and worthless techno-fix if the Aswan High Dam were simply demolished! A new ice age could cause global sea level to lower! Johnson's neo-ice age concept of past and future climate changes is fully and carefully described in Secrets of the Ice Ages: The Role of the Mediterranean Sea in Climate Change (2002). As of now, the scientific controversy over R. G. Johnson's theory remains scientifically unresolved (Bryden and Webb, 1998).
The world's first commercial hydroelectric dams began operation from 1880-82. Commencing about 1929, and ceasing by 1952, the German architect Herman Sorgel proposed the construction of the world's most powerful hydroelectric dam, which he estimated capable of generating 50,000 Mwe at the Strait of Gibraltar alone, when the Mediterranean Sea had been reduced by 200 m. Sorgel's "Atlantropa Project" means a macroproject that suggests a "turning towards the North Atlantic Ocean". All electricity manufactured at the Gibraltar Strait Dam's powerhouses will be efficiently transmitted to consumers by superconducting power-lines (Hawsey, 2005). R .B. Cathcart (1998) opted for an adapted Sorgelian edifice that might operate successfully with only a 50 m reduction of that physiographic relief unit's Mediterranean Sea Basin-wide controlled sea level – in fact, an artificial seawater still-stand – uncovering a new area of land amounting to about 8% of the Mediterranean Sea's present surface area. Neither Sorgel nor Cathcart thought a calculated optimal efficiency level for an impermeable gravity dam manipulating all natural seawater inflow through the Strait of Gibraltar was significant or useful. About 10,000 years BP, the Mediterranean Sea was 50 m lower than today. All other factors remaining the same, if the seawater surface was under air that was 50 m thicker by 2050, then it is likely that the air's temperature at the air-sea boundary would be about 0.30°C warmer. Adding the probable temperature increase due to global warming (say, 2°-30°C) by mid to late 21st century plus the "atmosphere thickening factor" of 0.30°C means that seawater evaporation may be greater than anticipated so far. In other words, a 50 m reduction might be finished in less than a century.
Many physical and biological changes will occur upon completion of a Gibraltar Strait Dam. For example, freshwater artesian springs that are (nowadays) undersea springs may become valuable in the future as sources of freshwater for new coastal settlements and farmlands (Ghannam, 1998) serving primarily Mediterranean Sea Basin peoples. France spent four million 2003 Euros to harness a submarine freshwater spring gushing 100 liters/sec from the seabed near the Franco-Italian border at a depth of 36 m. It seems such springs were beneficial to humans shortly after the Earth's most recent ice age (Faure, 2002), when global sea level was much lower than today. Fernando Gomez has examined some of the seawater chemistry consequences of a Gibraltar Strait closure (Gomez, 2003). The Mediterranean Sea's waters will become warmer and saltier and many extant species of its sparse life component will decline in mass or become extinct (Sardia, 2004).
Once a Gibraltar Strait Dam is emplaced, the Mediterranean Sea will have the character of an "aquarium" and, as such, can be monitored closely by a wireless ecological sensor network (Porter, 2005). Not only will macro-engineering be experimental (barrier building, harbor and city construction), but the macro-management of the megaproject will also be experimental! Collapse of the Gibraltar Strait Dam, from any cause, would foster catastrophic dam-break wave propagation with tsunami-like characteristics and effects upon the new and old shorelines of the Mediterranean Sea. A dam-break disaster of this magnitude has never before been physically or computationally modeled, but a start has been made in another context of oceanographic investigation (Speich, 1996). Sensitive DamFlow computer modeling applied to the particular problem at the Strait of Gibraltar ought to be helpful to investigators trying to assess the nature and scope of the hydraulic macro-problem (Pares, 2005). Such an infrastructure breakdown would be a gigantic emergency and restoration macro-management headache; in terms of public relations, it could be a long-term Earth system science and macro-engineering blemish! Since the induced reduction of the Mediterranean Sea will raise the world-ocean’s level by around 33 cm (Cathcart, 1995), the quick return of that longtime aerial water vapor export to the Mediterranean Sea as a single in-rushing liquid flood would adversely affect all of the world's seaports!
The world-ocean is the surface temperature boundary for the Earth-atmosphere over 71% of the planet's surface. A segment of the world-ocean, the Mediterranean Sea, is considered the "Mare Nostrum" of Earth system science (Krijgsman, 2002). Starting in late 2004, the most detailed ever heat map of the Mediterranean Sea – the world's largest inland sea – was being updated daily as part of the European Space Agency "Medispiration Project". A historiographer, Allan Megill, says the answer historians seek to the question of "what was actually the case?" in the recorded past is "recounting". Historical explanation, he wisely asserts, is dependent on a professional "recounting", which he likened to a process "like the winning of land from…[The Netherlands'] Zuider Zee" (Megill, 1989). A reduced Mediterranean Sea would be a maritime archaeological treasury. An in-depth recounting of the Atlantropa Project authored by Herman Sorgel in 1929 deserves reassessment in the event that global change challenges humans everywhere to macro-engineer their planetary homeland (Earth).
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