Lagoa das Sete Cidades
| Lagoa das Sete Cidades | ||
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| Geographical location | Ponta Delgada District , Sao Miguel , Azores , Portugal | |
| Drain | an artificial tunnel towards Mosteiros | |
| Places on the shore | Sete Cidades | |
| Data | ||
| Coordinates | 37 ° 51 '47 " N , 25 ° 47' 13" W | |
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| Altitude above sea level | 259 m | |
| surface | 4.37 km² | |
| length | 4.225 km | |
| width | 2.03 km | |
| volume | 40,500,000 m³ | |
| Maximum depth | 33 m | |
| Middle deep | 9.3 | |
Lagoa das Sete Cidades ( Portuguese for 'lake of the seven cities') is a lake in the crater of Sete Cidades in the Ponta Delgada district on the Portuguese Azores island of São Miguel . The lake consists of two sub-lakes, namely the larger northern part Lagoa Azul (Portuguese for 'blue lake') and the smaller southern part Lagoa Verde (Portuguese for 'green lake'), which are connected by a narrow passage over which a road bridge leads . The view from the crater rim of the lake is one of the greatest attractions of the archipelago .
description
With an area of 4.37 km², Lagoa das Sete Cidades is the largest lake in the Azores. It also contains almost half of the islands' freshwater resources. The lake measures a little more than four kilometers in length, two kilometers at its widest point and 33 meters at its deepest point. This makes it the deepest lake in São Miguel. The water surface is at an altitude of 259 meters above sea level. The crater walls rise steeply and their rim rises about 300 meters above the lake. The main viewing point, Vista do Rei, is located south of Lagoa Verde, also at this altitude. In the east lies the Pico da Cruz , which, with a height of 845 m, towers over the crater floor by almost 600 meters. Often, however, you cannot see the lake from above because of the fog or the clouds that stick to the mountain, while the view below on the crater floor can be absolutely clear. The lake is under protection as part of the Sete Cidades nature reserve . The village of Sete Cidades is located on the west bank of Lagoa Azul .
Emergence
In the past, where the Sete Cidades crater is today, there was an approximately 1200 m high volcano, the slopes of which were still cultivated by the first settlers on São Miguel. However, around the middle of the 15th century, the volcano erupted with a huge eruption. The volcanic cone was destroyed and today's crater was created; many more outbreaks followed. The ash that fell to the bottom of the crater during these eruptions sealed the bottom of the lake basin, so that the present-day lake could form over time.
Lagoa Azul and Lagoa Verde
Lagoa Verde owes its name to a phenomenon that occurs when sunlight hits the caldera . If you stand at the edge of the crater, the water of Lagoa Verdes appears greenish due to light reflections on the water surface that emanate from the dense coniferous forest that grows on the crater wall, which protrudes steeply upwards, while the water of the larger part of the lake has a blue color is expressed by the designation Lagoa Azul. After heavy rain, however, both lakes are cloudy and greenish.
According to an etiological legend , the lakes consist of the tears of two lovers. A princess had to part with her lover, a poor shepherd who had unsuccessfully asked for her hand, in order to marry a man her father had chosen for her. They met and kissed one last time where the two lakes meet today. The two lakes arose out of her farewell tears: the blue one from the tears of the princess's blue eyes and the green one from the green eyes of the shepherd. The legend contains a typical story from mainland Europe about the love of a young shepherd for a virgin to whom the land is subject.
Water balance and quality
Like many crater lakes, the Lagoa das Sete Cidades has no natural runoff. For this reason, the lake often overflowed its banks in the winter rains and flooded the village. A few stilt houses can still be seen in Sete Cidades today. The floods stopped when in 1936 a long, approximately 2 m high tunnel was dug from the north-western edge of the lake down to Mosteiros , which diverts excess water into the sea. Until the eighties of the twentieth century, the tunnel was also used by the population in dry seasons to get from one place to another. In addition to its actual job, it now mainly serves tourists as a holiday attraction.
Due to the intensive cattle grazing in the surrounding areas, many nutrients get into the water. The water quality has fluctuated between mesotrophic to eutrophic since the beginning of regular scientific observation of the lake in the 1990s . Even if these values have improved since 2000, the lake water is not clean. In 2002 a harmful concentration of cyanobacteria was measured in the Lagoa Azul . Since then, signs have been attached to the lake advising against coming into contact with the lake water for health reasons. Nevertheless, the lake is still used for swimming and surfing.
See also
literature
- D. Medeiros, JV Cruz, A. Malcata, S. Mendes: Monitorização da Qualidade da Água das Lagoas de São Miguel Miguel - Comparação de resultados entre 2001 and 2004. Governo regional dos Açores, Secretaria Regional do Ambiente e do Mar, Direcção Regional do Ordenamento do Território e dos Recursos Hídricos (Ed.), 2005, pp. 95–110 (PDF 3.66 MB)
- Joao Porteiro, Helena Calado, Margarida Pereira, José Eduardo Ventura, Luz Paramio: PLANEAMENTO BIOFÍSICO E GESTÃO DE ECOSSISTEMAS LACUSTRES. Universidade dos Açores, Ponta Delgada - Lisbon,> 2005 (PDF 0.5 MB)
- MC Medeiros, V. Gonçalves, DM Pacheco, AG Brito, R. Coutinho, MCR Santos, FJP Santana: Monitorização in continuum da Lagoa das Sete Cidades. Ponta Delgada - Lisbon, no year (PDF 0.7 MB)
Web links
Individual evidence
- ↑ a b Joao Porteiro, Helena Calado, Margarida Pereira, José Eduardo Ventura, Luz Paramio: PLANEAMENTO BIOFÍSICO E GESTÃO DE ECOSSISTEMAS LACUSTRES. Universidade dos Açores, Ponta Delgada> 2005, p. 14 (PDF 0.5 MB)
- ^ Governo dos Açores: Protected Landscape Area of Sete Cidades. URL: http://parquesnaturais.azores.gov.pt/en/smiguel-eng/what-visit/protected-areas/protected-landscape-area/sete-cidades accessed on October 6, 2011
- ↑ Michael Bussmann: Azores. 4th edition. Michael Müller Verlag, Erlangen 2010, ISBN 978-3-89953-576-1 , p. 194
- ↑ a b Michael Bussmann: Azores. 4th edition. Michael Müller Verlag, Erlangen 2010, ISBN 978-3-89953-576-1 , p. 195
- ↑ Michael Bussmann: Azores. 4th edition. Michael Müller Verlag, Erlangen 2010, ISBN 978-3-89953-576-1 , p. 196
- ↑ Monitorização da Qualidade da Água das Lagoas de São Miguel Miguel 2001-2004, p. 109