Description of the site

As mentioned before, the mouth of the Arade River has changed substantially in time.  According to a 12th-Century report the mouth of the river was further out, near Ponta do Altar (see Fig. 1), and the river ran close to the cliffs situated on its left margin.[1]  This is confirmed in an 1800 report signed by Baltazer de Azevedo Coutinho, Captain of the Royal Corp of Engineers.[2]

Previously encompassing a few small islets and sandbanks in middle of its present bed, the Arade River ran to the sea through three narrower channels.  The earthquake of 1755 is said to have been at least partially responsible for the disappearance of these islets, and the change of the river's course about one kilometer to the west.

 

Fig. 6 - The Arade River mouth after a 1648 map.[3]

 

As a consequence of the changes in its course, and the silting provoked by the tidal waves of 1755, the Arade mouth presented a depth of only 4.80 m on high tide and 2.4 m at the lowest tide in the early 19th century.[4]

After the changes produced by the 1755 earthquake an accumulation of sand on both margins of the Arade mouth consolidated its new course, and winter floods broke through the SW channel.

In the beginning of the 20th century the beauty of the landscape and the amenity of the climate brought the first families to spend holidays at Praia da Rocha, which was the best known and more frequented in the whole south of Portugal already by 1910.

 

Fig. 7 - The Arade River mouth after a 1916 map.[5]

 

Data from the period 1916-1926 shows that the mouth of the Arade River was very unstable, with depths varying widely, as the main channel path varied.

In 1926 and 1927 the sandbanks were dredged for the first time, as a developing fishing industry, associated to a growth of a young preserve industry, called for better conditions for the vessels entering and leaving the river.

Although impressive - a total of 360.000 m3 of sand were dredged and deposited on the bottoms in front of Ponta do Altar promontory - these dredging works were not very successful, as the river quickly re-established its ancient form.  By 1936 the river mouth was again shallow and unstable.  But the dredging works had another effect: the large sandy stripe that formed Praia da Rocha started to diminish.

 

Fig. 8 - The Arade River mouth after a 1934 map.[6]

 

During the decade of the 1950s two jetties were built to protect and regularize the mouth of the river, and allow the construction of a commercial harbor at Portimão.  The construction of the first of two jetties that protect the harbor was started in 1948 and interrupted soon after.  Started again in 1951, these long structures were soon ready.

Although the expected regularization of the river bottom was achieved, the construction of these jetties may have impeded the natural shift of sediments along the coast, and furthered the disappearance of sand in Praia da Rocha, situated immediately to the west.

In 1968 an area inside the jetties - in the plan (Fig.11) marked "anteporto" - was dredged to a depth of eight meters, and the sand deposited in front of Praia da Rocha, in the hope that this could stop the disappearance of that beach.

This strategy did not work, and in 1970 a large portion of this "anteporto" area was dredged again to a depth of eight meters.  This time the sediments - about 830.000 m3 - were deposited on the beach (Praia da Rocha).

Fig. 9 - The Arade River mouth after a 1967 map showing the jetties.[7]

 

Fig. 10 - The Arade River mouth after a 1970 map showing the recharge of Praia da Rocha with the sediments dredged.[8]

Fig. 11 - The Arade River mouth after the dredging works, after a 1970 map.[9]

 

During the course of these dredging works, in the summer of 1970, five shipwreck hulls are said to have been hit by the dredges.  In spite of all the attention given to it by the press, which included the national television, nothing was done on behalf of these shipwrecks, and they were either destroyed or left to rot, as they were exposed on the slope of the dredged area, when the sediment shifted down, to establish a natural bank.

Maintenance of the depths obtained in 1970 forced other dredging campaigns during the decade of the 1980s, starting on that same year.

Other shipwrecks are said to have been hit and partially or totally destroyed, generating further public outcry, which does not seems to have daunted neither the harbor authorities, nor the central government.

A team from the Museu Nacional de Arqueologia, under the direction of Francisco Alves, conducted a survey at the local, but did not find any of the shipwrecks.  This action however triggered the interest of the Comissao Nacional Provisoria de Arqueologia Subaquatica, and the shipwrecks were given a certain level of protection as part of Portugal's cultural heritage by the government.

Subsequent dredging works were conducted with less public outrage, since the sediments were dumped once again off Ponta do Altar, and although there are scattered reports of destruction and alleged plundering - curiously attributed to the destroyers themselves, the crews of the Dutch dredging ships contracted for the works - nobody knows exactly what or how much was destroyed.

In 1987 Museu Nacional de Arqueologia promoted a survey in the Arade mouth waters, under the direction of Jean-Yves Blot, but none of the sites could be located.[10]

In the following decade, the 1990s, legislation was issued that protected the Portuguese underwater cultural heritage, and forced the promoters of these type of works to evaluate its impact on the underwater cultural heritage.  Moreover, the impunity with which the harbor authorities acted in the previous decades came to an end with the creation in 1997 of the Instituto Português de Arqueologia (IPA), a state agency charged with the coordination of national and local archaeological policies that included a department dedicated to the study and protection of the underwater cultural heritage (CNANS).

In this context the harbor authority was barred from promoting further dredging works before the whole Arade estuary was surveyed and its important heritage recorded.  An agreement was reached with the local municipality, CNANS, and a local group, GEO, especially active in the promotion of the regional underwater cultural heritage.

During the summers of 1999 and 2000 the GEO divers surveyed an area of almost one square kilometer in mouth of the Arade River and located a large number of interesting spots, some consisting of only a few amphora shards, and other encompassing extensive hull remains.

In the summer of 2001 I was invited to participate in a closer inspection of the most promising sites located by the GEO team.  With the help of one of the 1970 divers, Helder Mendes, one of these sites was immediately identified as one of the shipwrecks hit by the dredges in that year.  It was decided to start an excavation of this site, which was called Arade 1.

The hull remains were partially excavated, and a 1/1 accurate drawing was done on perfectly horizontal transparent slates with one square meter each.

During the following winter I was invited by the director of CNANS, Francisco Alves, to complete the excavation and promote the study and publication of this shipwreck.  The idea of an INA / Texas A&M University summer school was born from this invitation at that time.


[1] Gomes, Nelson Augusto, and Weinholtz, Manuel de Bivar, "Estudo da evolução do estuário do Arade e das praias adjacentes", Portos e Obras Marítimas, document from Direcção de Serviços Marítimos in the library of the Museu Municipal de Portimão:  III-4-5.

[2] Ibidem: III-4-5.

[3] Weinholtz, M. de Bivar,  Anteporto de Portimão e Praia da Rocha, Evolucao.  Lisboa:  Direccao Geral de Portos, 1970-1980: 6.

[4] Loureiro, Adolpho,  Op. cit.: 187.

[5] Gomes, Nelson Augusto, and Weinholtz, Manuel de Bivar, Op. cit.: III-4-17.

[6] Gomes, Nelson Augusto, and Weinholtz, Manuel de Bivar, Op. cit.: III-4-17.

[7] Gomes, Nelson Augusto, and Weinholtz, Manuel de Bivar, Op. cit.: III-4-20.

[8] Ibidem: III-4-20.

[9] Gomes, Nelson Augusto, and Weinholtz, Manuel de Bivar, Op. cit.: III-4-22.

[10] Alves et. al.," Sistemas de deteccao geofisica em arqueonautica utilizados em Portugal: os casos do Arade 1, Redoutable e Alfeizerao," in Geociencias, 5.1: 135 (abstract).