As there seems to be so much curiosity about the PSLP, we are taking this opportunity to try to explain what it consists of and what we hope to learn over the next few years. The Portuguese Sea- Level Project was conceived after the London Conference, 2016. At that time Professor Araújo presented a paper on tide gauges and sea-level change around the Iberian Peninsula.
We believe that there are many factors affecting sea level around the Iberian Peninsula, including neo-tectonic activity, because Iberia is in the exact crossroads of the Atlantic and Mediterranean tectonic areas. We see both uplift and subsidence at different places along the coast, both of which affect our perception of local sea level.
Coastal erosion is an expensive problem around the world and also in Portugal, dependent on many more things than just the minimal sea level changes that we find in places like Cascais (1,3mm/yr.). One of the biggest causes of coastal erosion is changes in the sediment budget caused by hydroelectric dams on the major rivers. This is further exacerbated by massive coastal constructions designed to protect the coast and the harbors but which that increases the erosion problem down drift, producing a "comb" shaped coastline.
Unfortunately, recent data from PSMSL are not available for Portugal.
Because of that, at the SONEL site the absolute sea level trends don’t contain Portuguese stations. Nevertheless, we can see that sea level changes on the Iberia peninsula are mostly connected to land movements recorded by GPS and are quite moderate. The only exception is Cádiz where a GPS 11km away from the tide gauge was used. With this GPS data, SONEL proposes an absolute sea level change of 4.12±0.54 mm/year, that seems quite unlikely!
For Tarifa the combined velocity is 1.96±0.82 mm/year. For Ceuta the combined velocity of 0.62±0.62 mm/year. Considering that these three stations are located quite close in geographical terms, absolute sea level cannot be so different between these three sites.
In Europe, according to SONEL, only Klaipeda, in Lithuania has a reading similar to Cadiz: “combined sea level change”: 4.12±0.54 mm/year.
So, the proclamation of a 4mm/yr. at Cascais (Carlos Antunes website) seems quite exaggerated, being based on a ca 10yr. series and an erroneous interpretation of the land movements that can be find at SONEL site
We have been examining the entire Portuguese coast, looking for a reliable and simple solution to getting accurate measurements of Sea-Level change. So far, this work is somewhat stymied by the nature of the coast. But we plan to continue working until a solution is found.
Another inquiry we are pursuing is how the coming Grand Solar Minimum will affect the weather and Sea-Level rise or fall in Portugal north of Lisbon. This will require a lot of digging back in history to find out how seriously agriculture was affected during previous Grand Solar Minima. Northern Portugal is heavily agricultural, growing wine grapes, cattle and sheep, livestock feed, fruits and vegetables. The Douro Valley is home to the vineyards that produce Port wine. There are reliable records from the LIA that will give us clues as to what to expect.
websites
http://www.sonel.org/-Sea-level-trends-.html?lang=en http://webpages.fc.ul.pt/~cmantunes/hidrografia/hidro_mares.html
Coastal erosion: the case of the beaches of Vila Nova de Gaia. Consequences of the waste-water outlet (Gaia littoral)
Viriato Silva and M. Assunção Araújo, CEGOT-FLUP [email protected] – [email protected]
1. Several natural phenomena may contribute to coastal erosion. For Bird (1993), about 90% of the world's coastlines are in a process of erosion. However, it is estimated that sea level variation only represents about 10% of the coastal reduction (J.M. A. Dias et al., 1997).
The rise in sea level also forces rivers to encroach on their estuaries in order to reach a new equilibrium profile according to the new sea level. This layer of sediments, in broad estuaries, may represent a non-negligible part of the problem. (M. Araújo, (2002).
It has also been hypothesized that the stock of sediments that the sea dragged on the coast during the Flandrian transgression (Paskoff, 1985, Granja and Carvalho, 1995) has been exhausted.
Of course, the vulnerability of coastal regions to erosion still depends on other factors. One of the most decisive has to do with the geological substrate. In cliffs consisting of poorly consolidated material the erosion is faster than that of granite cliffs or of massive limestones. The tectonic movements, even when they occur in very long-time intervals, interfere and their influence cannot be ignored (Araújo, 2004).
2. Coastal defences and protection efforts are many and varied, in particular through construction of defences like seawalls, breakwaters, jetties and spurs. However, by disrupting the normal development of coastal drift, all transverse works eventually retain sediment at the updrift side of the structure. This retention of sediment will cause a deficit to down drift areas, which usually results in a retreat from the coastline (Araújo, 2004).
Over the past few decades, coastal plans (POOCs) have undertaken the construction of footbridges that allow access to the beaches, while still preserving the vegetation that protects the dunes, and also constructing palisades that can create new dunes. This new environmental awareness took some time to implement. For decades, people have been building clandestine holiday homes in the dunes and other places in the maritime public domain (Araújo, 2004).
3. In the case of the Douro River, it is estimated that about 86% of its capacity to feed the coastal areas of northern Portugal was lost as a result of the construction of hydroelectric dams (Mota Oliveira, 1990). In the case of the Crestuma dam, located very close to the mouth of the river, it resulted in a great reduction in sediment transport capacity.
4. Among the cases of damage caused by human intervention, the Waste-water Treatment Plant, Gaia Litoral, was inaugurated in 2003, which has an underwater extension of 2.5 km, with its final effluent discharged into the sea at a depth of 30 meters. (Fig. 1a, before the waste-water outlet construction) and (Fig. 1c, after its construction).
The block protection to the effluent outlet initiated a strong beach erosion to the south of Madalena beach, and even before the inauguration of waste water plan, in 31/December 1998, a restaurant called Titanic, 3700 meters to the south of the waste-water outlet was partially destroyed at Francelos beach (Fig. 1b).
So, as a conclusion: the combined effect of dam sediment retention and anthropogenic works interfering in littoral drift seems much more important than the sea level rise that is quite small - if existent – in this area of Portuguese coastline.
Colocado por: JoelMA não ser que o OMS também esteja comprada...
Colocado por: JoelM
Quando tem de ir buscar uma noticia a um "site" chamado de Quali.pt, está tudo dito...
Que alimente teorias da conspiração, tudo bem, agora gostaria de saber é que fonte é que é isenta para ti e de que lado está a clara verdade! (em relação à poluição matar milhoes de pessoas por ano, directa ou indirectamente)
Según un estudio del British Medical Journal (BMJ), una de las revistas médicas de referencia, un informe clave de la OMS ocultó los vínculos financieros entre sus expertos y las farmacéuticas Roche y Glaxo, fabricantes de Tamiflu y Relenza, los fármacos antivirales contra el virus H1N1. Ese fue el informe que instó a los Gobiernos a apilar reservas de esos medicamentos, por valor de unos 6.000 millones de dólares (4.900 millones de euros). Las críticas del British Medical Journal se suman a las del Consejo de Europa, que recientemente también acusó a la OMS de opacidad, aunque por otra razón: que los 16 miembros del comité de emergencia que asesoró durante la crisis a la directora del organismo, Margaret Chang, son secretos.
Colocado por: JoelMQue alimente teorias da conspiração, tudo bem
Colocado por: AlarmesdoMecoIsso sim era uma vacina..
Colocado por: JoelMSó tenho pena que
Colocado por: JoelM
como passo o tempo ou deixo de passar não é da sua conta!
Colocado por: JoelM
não é por andar aqui a postar imagens com frases feitas que vai parecer mais inteligente, já diz o ditado, contra factos não há argumentos!
Colocado por: euNo caso da gripe A, os media também tiveram muita culpa ao exagerar o perigo.