The ups and downs of a mega-lake

Phys dot org ^ | July 9, 2020 | University of Tubingen

[SunkenCiv]

Together with an international team, researchers of the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen reconstructed the 20,000-year-old history of the mega-lake Chew Bahir in a remote valley in Southern Ethiopia. Led by Annett Junginger, the scientists were able to show that the lake underwent rapid water level changes in the course of its history, which had a direct impact on the local population. The study was recently published in the journal Frontiers in Earth Science.

Water is mankind's most important basic resource. From the beginning until today, humans of all cultures sought out settlements not far from the presence of clean drinking water -- as has been the case for 20,000 years at what is now Lake Chew Bahir in Southern Ethiopia.

Currently, this lake is almost completely dry. "However, in the past, the lake often held an enormous volume of water and covered an area five times the size of Lake Constance," explains Markus Fischer, the study's lead author and a doctoral student at the University of Tübingen, and he continues, "Based on hydrological models and the lake's sediments, we were able to document enormous, rapidly changing shifts in the sea level over the course of the lake's history."

The international research team's modeling results and the lake sediments offer impressive evidence that the East African landscape repeatedly fluctuated between desert-like conditions and a gigantic lake; in many cases, the lake would dry out and refill with water within just a few decades. Rainfall during the frequently recurring wet phases was between 20 and 30 percent higher than today. "Those who grew up at a lake and possibly learned to fish there may have been confronted with a dried-out lakebed as adults," adds Fisher.

[SunkenCiv]

Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL | edited by David K. Wright | Frontiers in Earth Science

Overview of the study area, lake levels and lake-balance modeling results from previous an current studies: (A) Elevation map of Africa and the positions of major air boundaries and convergence zones during the NH summer. Indian Summer Monsoon (ISM), West African Monsoon (WAM), the Inter Tropical Convergence Zone (ITCZ), and Congo Air Boundary (CAB). (B) Elevation map of eastern Africa with the study area, major lakes, study area (white box) and the CAB position in July. (C,D) Known paleo-lake depths within the EARS during the African Humid Period (AHP) and published paleo-precipitation rates estimates using different lake-balance approaches and associated references. (E) Transect of the EARS from north-east to south, with modern and paleo level lake extents (light and dark blue, respectively), the study area (red box), and major drainage direction (dotted line). North-South transect of the eastern branch of the EARS, with modern and paleo-lake extents (light and dark blue, respectively), the study area (red box), and major drainage direction (dotted line). The figure was modified after Junginger and Trauth (2013).

Figure 1

[SunkenCiv]

Figure 2. Geographical features of the studied lake basins: (A) Modern catchment boundaries, monthly temperature means in °C and precipitation in mm/month (IRI, last accessed 11/2019), overflow sill locations (white-blue circles), and paleo-lake dimensions with modern/paleo-depths in numbers. (B-E) Modeling outputs of paleo-lake Chew Bahir's dimension during different lake filling steps from modern to +5, +20, and +45 m when reaching the overflow level. (F-J) Pictures from study sites by A. Junginger.

Figure 2

[SunkenCiv]

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[SunkenCiv]

[lee martell]

Oh, you said Mega-Lakes,
Not MAGA-Lakes....Got it.

Now that you bring it up, rumor is the Sahara Desert was lush and green with plant life, rivers and even forests about 11K years ago. Some think farmers and their grazing animals turned every place they lived into scrub and desert land over time.

[Chainmail]

On a related note, Ethiopia with the splendid support of the Chinese, are damming the Blue Nile to form a much larger lake - and starve Sudan and Egypt of their water source.

Anybody looking at deposits made to the Clinton Foundation while this was in the planning process?

[Red Badger]

.... the scientists were able to show that the lake underwent rapid water level changes in the course of its history,...

Raining continuously for 40 days and 40 nights will do that.................

[MeganC]

“Based on hydrological models and the lake’s sediments, we were able to document enormous, rapidly changing shifts in the sea level over the course of the lake’s history.”

What the hell does sea level have to do with the level of water in the lake?

[SunkenCiv]

The dam has been under construction for years and the filling of the reservoir will take between 5 and 15 years based on average output of the river and amount of water permitted through the dam by agreement. IOW, no, there won't be a war. And the construction took longer because the foundations had to be made deeper due to the underlying strata.

[JeanLM]

The population of the world 11K years ago couldn’t have made the Sahara a desert. Climate changes without man’s influence is the jist of the article.

Right now there is a huge aquifer under the sahara that the Lybians tapped in a huge water project. Water comes and goes all around the world depending on weather and other factors beyond our models and influence.

[marktwain]

“sea level” ha,ha! Probably a typo which should have been “lake level”!

[JeanLM]

https://www.water-technology.net/projects/gmr/

Libyan project

[SunkenCiv]

Ethiopia had previously pushed to start filling the gigantic Nile River dam next month despite vehement opposition from downstream Egypt and Sudan, and the dispute was raised with the UN last week.

The office of Egyptian President Abdel Fattah al-Sisi said Friday that "a legally binding final agreement for all parties stressing the prevention of any unilateral moves, including the filling of the dam, will be sent in a letter to the UN Security Council to consider it in its session discussing the Renaissance Dam issue next Monday."

Sudan's Prime Minister Abdalla Hamdok was more forthcoming, saying in a statement that "it has been agreed upon that the dam filling will be delayed until an agreement is reached".

His office said technical committees for all three countries will try to hammer out a conclusive deal within two weeks as suggested by Ethiopia.

"Sudan is one of the biggest beneficiaries from the dam and also one of the biggest losers if risks are not mitigated, thus it urges Egypt and Ethiopia to the impending necessity... of finding a solution," Hamdok added.

The minor breakthrough came after an emergency African Union Executive Council virtual session chaired by South African president Cyril Ramaphosa. Other attendees included Kenyan President Uhuru Kenyatta.

Egypt, Ethiopia and Sudan agree to delay filling dam | AFP | June 26, 2020

[SunkenCiv]

from the Sahara keyword:

• Entomologist Confirms First Saharan Farming 10,000 Years Ago [2018]
• More Evidence of a Wet Sahara [2017]
• Fossil of massive crocodile found on edge of Sahara desert [2016]
• A Carpet of Stone Tools in the Sahara [2015]
• Ancient Africans used 'no fly zones' to bring herds south [2015]
• NASA video shows how dust from Sahara Desert fuels Amazon rain forest [2015]
• Violence and climate change in prehistoric Egypt and Sudan [2014]
• Ancient bone fragments help describe diet, health of Saharan ancestors [2014]
• Study Confirms Ancient River Systems in Sahara 100,000 Years Ago [2013]
• Mineral dust plays key role in cloud formation and chemistry [2013]
• Lost Civilization Discovered in Sahara Desert [2011]
• Ancient Egypt was destroyed by drought, discover Scottish experts [2011]
• Fish Swam the Sahara, Bolstering Out of Africa Theory [2010]
• Lost Cities of the Sahara [2010]
• Geology Picture of the Week Extra: GoogleEarth searcher finds pristine impact crater in Egypt [2010]
• Strange Ancient Crocodiles Swam the Sahara [2009]
• Stone Age humans crossed Sahara in the rain [2009]
• Giant stone-age axes found in African lake basin [2009]
• Graves Found From Sahara's Green Period [2008]
• Graves Found From Sahara's Green Period [2008]
• US scientists find stone age burial ground in Sahara [2008]
• In Search Of The Lost Sahara [2008]
• Once Lush Sahara Dried Up Over Millennia, Study Says [2008]
• Sahara dried out slowly, not abruptly: study [2008]
• The Tassili n'Ajjer [Algeria] : birthplace of ancient Egypt ? [2008]
• Egypt's Earliest Agricultural Settlement Unearthed [2008]
• UN vandals spray graffiti on Sahara's prehistoric art [2008]
• Ruins of 7,000-year-old city found in Egypt oasis [2008]
• Maltese claims extraordinary discovery in Sahara desert [2007]
• Space Data Unveils Evidence of Ancient Mega-lake in Northern Darfur [2007]
• The African Source Of The Amazon's Fertilizer [2006]
• Exodus From Drying Sahara Gave Rise to Pharaohs, Study Says [2006]
• Sahara Desert Was Once Lush and Populated [2006]
• Ancient lakes of the Sahara [2006]
• Ancient drought 'changed history' [2005]
• Stone Age Cemetery, Artifacts Un Earthed In Sahara [2005]
• Prehistoric Desert Town Found In Western Sahara (15,000 Years Old) [2004]
• Scientists Explore Lakefront Property, in the Sahara [2004]
• African Ice Core Analysis Reveals Catastrophic Droughts, Shrinking Ice Fields, Civilization Shifts [2002]

[ckilmer]

the new numbers are about 5500 years ago. The sahara then dried up in only a couple centuries or less

[fieldmarshaldj]

The lake was obviously racist. It didn’t want to provide water for thirsty Africans.

[Ozark Tom]

The Sahara has a regular periodic water cycle which reached peak rainfall about 20,000 years back. There are many fresh water aquifers within reach of deep-well pumping systems. Some produce a scalding hot sanitized outflow when tapped.

[SunkenCiv]

The White Nile is racist, and notice that most of the Nile waters comes from the Blue Nile, not the Red Nile? Figures. /jk

[colorado tanker]

It’s good to live at a big river’s headwaters . . .

[SunkenCiv]

Herodotus discusses Lake Tritonis.

The sea-coast beyond the Lotophagi is occupied by the Machlyans, who use the lotus to some extent, though not so much as the people of whom we last spoke. The Machlyans reach as far as the great river called the Triton, which empties itself into the great lake Tritonis. Here, in this lake, is an island called Phla, which it is said the Lacedaemonians were to have colonised, according to an oracle.

The following is the story as it is commonly told. When Jason had finished building the Argo at the foot of Mount Pelion, he took on board the usual hecatomb, and moreover a brazen tripod. Thus equipped, he set sail, intending to coast round the Peloponnese, and so to reach Delphi. The voyage was prosperous as far as Malea; but at that point a gale of wind from the north came on suddenly, and carried him out of his course to the coast of Libya; where, before he discovered the land, he got among the shallows of Lake Tritonis. As he was turning it in his mind how he should find his way out, Triton (they say) appeared to him, and offered to show him the channel, and secure him a safe retreat, if he would give him the tripod. Jason complying, was shown by Triton the passage through the shallows; after which the god took the tripod, and, carrying it to his own temple, seated himself upon it, and, filled with prophetic fury, delivered to Jason and his companions a long prediction. "When a descendant," he said, "of one of the Argo's crew should seize and carry off the brazen tripod, then by inevitable fate would a hundred Grecian cities be built around Lake Tritonis." The Libyans of that region, when they heard the words of this prophecy, took away the tripod and hid it.

The next tribe beyond the Machlyans is the tribe of the Auseans. Both these nations inhabit the borders of Lake Tritonis, being separated from one another by the river Triton. Both also wear their hair long, but the Machlyans let it grow at the back of the head, while the Auseans have it long in front. The Ausean maidens keep year by year a feast in honour of Minerva, whereat their custom is to draw up in two bodies, and fight with stones and clubs. They say that these are rites which have come down to them from their fathers, and that they honour with them their native goddess, who is the same as the Minerva (Athene) of the Grecians. If any of the maidens die of the wounds they receive, the Auseans declare that such are false maidens. Before the fight is suffered to begin, they have another ceremony. One of the virgins, the loveliest of the number, is selected from the rest; a Corinthian helmet and a complete suit of Greek armour are publicly put upon her; and, thus adorned, she is made to mount into a chariot, and led around the whole lake in a procession. What arms they used for the adornment of their damsels before the Greeks came to live in their country, I cannot say. I imagine they dressed them in Egyptian armour, for I maintain that both the shield and the helmet came into Greece from Egypt. The Auseans declare that Minerva is the daughter of Neptune and the Lake Tritonis -- they say she quarrelled with her father, and applied to Jupiter, who consented to let her be his child; and so she became his adopted daughter. These people do not marry or live in families, but dwell together like the gregarious beasts. When their children are full-grown, they are brought before the assembly of the men, which is held every third month, and assigned to those whom they most resemble...

Thus from Egypt as far as Lake Tritonis Libya is inhabited by wandering tribes, whose drink is milk and their food the flesh of animals. Cow's flesh, however, none of these tribes ever taste, but abstain from it for the same reason as the Egyptians, neither do they any of them breed swine. Even at Cyrene, the women think it wrong to eat the flesh of the cow, honouring in this Isis, the Egyptian goddess, whom they worship both with fasts and festivals. The Barcaean women abstain, not from cow's flesh only, but also from the flesh of swine.

West of Lake Tritonis the Libyans are no longer wanderers, nor do they practise the same customs as the wandering people, or treat their children in the same way. For the wandering Libyans, many of them at any rate, if not all -- concerning which I cannot speak with certainty -- when their children come to the age of four years, burn the veins at the top of their heads with a flock from the fleece of a sheep: others burn the veins about the temples. This they do to prevent them from being plagued in their after lives by a flow of rheum from the head; and such they declare is the reason why they are so much more healthy than other men. Certainly the Libyans are the healthiest men that I know; but whether this is what makes them so, or not, I cannot positively say -- the healthiest certainly they are. If when the children are being burnt convulsions come on, there is a remedy of which they have made discovery. It is to sprinkle goat's water upon the child, who thus treated, is sure to recover. In all this I only repeat what is said by the Libyans.

The rites which the wandering Libyans use in sacrificing are the following. They begin with the ear of the victim, which they cut off and throw over their house: this done, they kill the animal by twisting the neck. They sacrifice to the Sun and Moon, but not to any other god. This worship is common to all the Libyans. The inhabitants of the parts about Lake Tritonis worship in addition Triton, Neptune, and Minerva, the last especially.

The Histories: Book IV Melpomene
Herodotus
tr by George Rawlinson

[may be a dead link]