Lake Afrera#Salt extraction
{{short description|Lake in Ethiopia}}
{{Infobox body of water
| name = Lake Afrera
| image = ET Afar asv2018-01 img113 Afdera.jpg
| alt = Photograph of the lake with a beach in the foreground
| caption =
| image_bathymetry =
| caption_bathymetry =
| location = Afar Depression
| coords = {{coord|13|17|N|40|55|E|region:ET_type:waterbody|display=inline,title}}
| pushpin_map = Ethiopia
| type =
| inflow =
| outflow =
| catchment =
| basin_countries = Eritrea, Ethiopia
| length =
| width =
| area = {{convert|114.8|km2|mi2|0|abbr=on}}
| depth =
{{convert|20.9|m|ft|abbr=on}}
| max-depth =
{{convert|80|m|ft|abbr=on}}
| volume =
{{convert|2.4|km3|cumi|abbr=on}}
| residence_time =
| shore =
| elevation = {{Convert|-112|m|ft|0|abbr=on}}
| islands = Franchetti Island
| cities =
| embedded = {{Infobox mapframe|wikidata=yes|zoom=10|marker=natural|coord={{WikidataCoord|display=i}}}}
}}
Lake Afrera (in Italian Lake Giuletti) is a hypersaline lake in northern Ethiopia. Located in Kilbet Rasu, Afar Region, it is one of the lakes of the Danakil Depression. It has a surface of {{Convert|117|km2|mi2|0|abbr=on}} and holds 2.4 km3 of brine.{{Cite journal |last1=Schaegis |first1=Jean-Charles |last2=Rime |first2=Valentin |last3=Kidane |first3=Tesfaye |last4=Mosar |first4=Jon |last5=Gebru |first5=Ermias Filfilu |last6=Atnafu |first6=Balemwal |last7=Foubert |first7=Anneleen |date=2021-07-01 |title=Novel Bathymetry of Lake Afdera Reveals Fault Structures and Volcano-Tectonic Features of an Incipient Transform Zone (Afar, Ethiopia) |journal=Frontiers in Earth Science |language=English |volume=9 |doi=10.3389/feart.2021.706643 |doi-access=free |bibcode=2021FrEaS...9..530S |issn=2296-6463}} The maximal depth of Lake Afdera is 80 m in the northern basin and 76 m in the southern basin. No major river drain the lake. It is fed by hot springs along the shores of the lakes.{{Cite journal |last1=Bonatti |first1=Enrico |last2=Gasperini |first2=Elia |last3=Vigliotti |first3=Luigi |last4=Lupi |first4=Luca |last5=Vaselli |first5=Orlando |last6=Polonia |first6=Alina |last7=Gasperini |first7=Luca |date=2017-05-01 |title=Lake Afrera, a structural depression in the Northern Afar Rift (Red Sea) |journal=Heliyon |language=English |volume=3 |issue=5 |pages=e00301 |doi=10.1016/j.heliyon.2017.e00301 |doi-access=free |issn=2405-8440 |pmc=5443967 |pmid=28560355|bibcode=2017Heliy...300301B }}
It is also known as Lake Giulietti, the name Raimondo Franchetti gave it after the Italian explorer Giuseppe Maria Giulietti was slain by Afars southwest of the lake.Jon Kalb, Adventures in the Bone Trade (New York: Copernicus Books, 2001), p. 72 Another name for this body of water is Lake Egogi (or Egogi Bad), which is the name L. M. Nesbitt's Afar guide gave it when the Italian explorer became the first European to see it in 1928.Nesbitt, Hell-Hole of Creation: The Exploration of Abyssinian Danakil (New York: Alfred A. Knopf, 1935), p. 337
The single island in Lake Afrera, Franchetti Island (also known as "Deset"), located in the southern part of the lake, is considered the lowest-lying island in the world.Philip Briggs, Ethiopia: The Bradt Travel Guide, 5th edition (Chalfont St Peters: Bradt, 2009), p. 314
Unlike other saline lakes in Ethiopia (e.g., Lakes Abijatta, Shala, and Chitu), the pH of Lake Afrera is low and in the acidic range. Although little studied, a few species of fish are hosted by Lake Afrera, including two endemics: Danakilia franchettii (a cichlid) and Aphaniops stiassnyae (syn. Lebias stiassnyae; a pupfish).[http://www.feow.org/ecoregion_details.php?eco=527 "527: Western Red Sea Drainages"] {{webarchive|url=https://web.archive.org/web/20111005203746/http://www.feow.org/ecoregion_details.php?eco=527 |date=2011-10-05 }}, Freshwater ecosystems of the world website (accessed 11 November 2009)
Salt extraction
File:Ethiopie-Lac salé Afdera (8).jpg
Rock salt has been mined at Lake Afrera, and the surrounding part of the Afar Depression, for centuries. Lt. Lefebvre recorded some of the hazards of mining salt from the Depression, which he heard from one of the miners himself:
He said that this lake often changes its shape and place, which he expressed in these terms: the lake moves. Often, he added, on going to a place which the evening before was quite solid, you suddenly break through, and disappear in the abyss. But what is more frightful is the overflow of the waters: sometimes the lake rises like a mountain, and falls again into the plain like a deluge; entire caravans, men and beasts are engulphed. There are, however, precursory signs, of which mounted men only can take advantage, by flying at the utmost speed of the animals; occasionally some of them have thus escaped, and it is from them these terrible details are procured.Henry James, Routes in Abyssinia; Presented to the house of Commons, in pursuance of their Address dated November 26, 1867 (London, 1867), p. 200
File:ET Afar asv2018-01 img114 Afdera.jpg
More recently, the Ethiopian Mineral Resources Development Enterprise has established the existence of 290 million tons of salt at Lake Afrera alone. Some local companies used to produce salt from the lake by pumping the brine into artificial ponds for evaporation and subsequent precipitation.[http://www.geology.gov.et/current%20exploration%20and%20mining.html Current Exploration and Mining] {{webarchive|url=https://archive.today/20070422062521/http://www.geology.gov.et/current%20exploration%20and%20mining.html |date=2007-04-22 }}, Geological Survey of Ethiopia Web Page (accessed 26 January 2009)
Following the 2011 eruption of Nabro, the lake is contaminated with sulfuric acid, making the salt inedible.{{Cite news|title=Eritrean Volcano Erupts Economic Mayhem for Ethiopia|first=Mahlet|last=Mesfin|work=Addis Fortune |url=http://www.addisfortune.com/Eritrean%20Volcano%20Erupts%20Economic%20Mayhem%20for%20Ethiopia.htm|date= June 12, 2011|url-status=usurped|archiveurl=https://web.archive.org/web/20110623142440/http://addisfortune.com/Eritrean%20Volcano%20Erupts%20Economic%20Mayhem%20for%20Ethiopia.htm|archivedate=June 23, 2011}}
Geology
The depression filled by Lake Afdera was formed by faults oriented in several directions linking the Erta Ale Volcanic Range, the Tat'Ali volcanic range, and Alayta volcanic range. Furthermore, a circular depression in the southern basin is interpreted to possibly represent a volcanic caldera.
Water source
Lake Afdera is fed by numerous hot springs around the lake and, possibly, by underwater springs. The waters of lake Afdera are saline but do not come from the sea. The continental waters gained their salinity by hydrothermal reactions with evaporites and basalts in the underground. The lake level varied significantly in the last tens of thousands of years. During the African Humid Period, the lake level was 50m higher than today and covered much larger area.{{Cite journal |last=Gasse |first=Françoise |date=January 1974 |title=Les Diatomées des Sédiments Holocènes du Bassin du Lac Afrera (Giulietti) (Afar Septentrional, Ethiopie). Essai de Reconstitution de l'Évolution du Milieu |url=https://onlinelibrary.wiley.com/doi/10.1002/iroh.19740590112 |journal=Internationale Revue der gesamten Hydrobiologie und Hydrographie |language=en |volume=59 |issue=1 |pages=95–122 |doi=10.1002/iroh.19740590112 |bibcode=1974IRH....59...95G |issn=0020-9309}} Since the 1960s' the lake level constantly fluctuated,{{Cite journal |last1=Nanis |first1=Hafid |last2=Aly |first2=Mohamed H. |date=2020-07-03 |title=Desegregation of remote sensing and GIS to characterize fluctuations in the surface water area of Afar Lakes, Ethiopia |url=https://www.tandfonline.com/doi/full/10.1080/10106049.2018.1559884 |journal=Geocarto International |language=en |volume=35 |issue=9 |pages=976–990 |doi=10.1080/10106049.2018.1559884 |bibcode=2020GeoIn..35..976N |issn=1010-6049}} but these variations were probably less than one meter in amplitude. This suggest that the lake level is controlled by climate and precipitations on the Ethiopian plateau or in the Danakil Alps.
