Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL
The Ethiopian rift is known for its diverse landscape, ranging from arid and semi-arid savannahs to high and humid mountainous regions. Lacustrine sediments and paleo-shorelines indicate water availability fluctuated dramatically from deep fresh water lakes, to shallow highly alkaline lakes, to comp...
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Frontiers Media S.A.
2020-06-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/article/10.3389/feart.2020.00197/full |
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| author | Markus L. Fischer Markus L. Fischer Monika Markowska Monika Markowska Felix Bachofer Verena E. Foerster Asfawossen Asrat Christoph Zielhofer Martin H. Trauth Annett Junginger Annett Junginger |
| author_facet | Markus L. Fischer Markus L. Fischer Monika Markowska Monika Markowska Felix Bachofer Verena E. Foerster Asfawossen Asrat Christoph Zielhofer Martin H. Trauth Annett Junginger Annett Junginger |
| author_sort | Markus L. Fischer |
| collection | DOAJ |
| description | The Ethiopian rift is known for its diverse landscape, ranging from arid and semi-arid savannahs to high and humid mountainous regions. Lacustrine sediments and paleo-shorelines indicate water availability fluctuated dramatically from deep fresh water lakes, to shallow highly alkaline lakes, to completely desiccated lakes. To investigate the role lakes have played through time as readily available water sources to humans, an enhanced knowledge of the pace, character and magnitude of these changes is essential. Hydro-balance models are used to calculate paleo-precipitation rates and the potential pace of lake level changes. However, previous models did not consider changes in hydrological connectivity during humid periods in the rift system, which may have led to an overestimation of paleo-precipitation rates. Here we present a comprehensive hydro-balance modeling approach that simulates multiple rift lakes from the southern Ethiopian Rift (lakes Abaya, Chamo, and paleo-lake Chew Bahir) simultaneously, considering their temporal hydrological connectivity during high stands of the African Humid Period (AHP, ~15–5 ka). We further used the Surface Energy Balance Algorithm for Land (SEBAL) to calculate the evaporation of paleo-lake Chew Bahir's catchment. We also considered the possibility of an additional rainy season during the AHP as previously suggested by numerous studies. The results suggest that an increase in precipitation of 20–30% throughout the southern Ethiopian Rift is necessary to fill paleo-lake Chew Bahir to its overflow level. Furthermore, it was demonstrated that paleo-lake Chew Bahir was highly dependent on the water supply from the upper lakes Abaya and Chamo and dries out within ~40 years if the hydrological connection is cut off and the precipitation amount decreases to present day conditions. Several of such rapid lake level fluctuations, from a freshwater to a saline lake, might have occurred during the termination of the AHP, when humid conditions were less stable. Fast changes in fresh water availability requires high adaptability for humans living in the area and might have exerted severe environmental stress on humans in a sub-generational timescale. |
| first_indexed | 2024-12-14T17:46:33Z |
| format | Article |
| id | doaj.art-977c55b892464e9885354c572e2a5c21 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-14T17:46:33Z |
| publishDate | 2020-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-977c55b892464e9885354c572e2a5c212022-12-21T22:52:44ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632020-06-01810.3389/feart.2020.00197542311Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBALMarkus L. Fischer0Markus L. Fischer1Monika Markowska2Monika Markowska3Felix Bachofer4Verena E. Foerster5Asfawossen Asrat6Christoph Zielhofer7Martin H. Trauth8Annett Junginger9Annett Junginger10Department of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanySenckenberg Centre for Human Evolution and Paleoenvironment (S-HEP), Tübingen, GermanyDepartment of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanyDepartment of Climate Geochemistry, Max Planck Institute for Chemistry, Mainz, GermanyEarth Observation Centre, German Aerospace Center (DLR), Wessling, GermanyInstitute of Geography Education, University of Cologne, Cologne, GermanySchool of Earth Sciences, Addis Ababa University, Addis Ababa, EthiopiaInstitute of Geography, University of Leipzig, Leipzig, GermanyInstitute of Geosciences, University of Potsdam, Potsdam, GermanyDepartment of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanySenckenberg Centre for Human Evolution and Paleoenvironment (S-HEP), Tübingen, GermanyThe Ethiopian rift is known for its diverse landscape, ranging from arid and semi-arid savannahs to high and humid mountainous regions. Lacustrine sediments and paleo-shorelines indicate water availability fluctuated dramatically from deep fresh water lakes, to shallow highly alkaline lakes, to completely desiccated lakes. To investigate the role lakes have played through time as readily available water sources to humans, an enhanced knowledge of the pace, character and magnitude of these changes is essential. Hydro-balance models are used to calculate paleo-precipitation rates and the potential pace of lake level changes. However, previous models did not consider changes in hydrological connectivity during humid periods in the rift system, which may have led to an overestimation of paleo-precipitation rates. Here we present a comprehensive hydro-balance modeling approach that simulates multiple rift lakes from the southern Ethiopian Rift (lakes Abaya, Chamo, and paleo-lake Chew Bahir) simultaneously, considering their temporal hydrological connectivity during high stands of the African Humid Period (AHP, ~15–5 ka). We further used the Surface Energy Balance Algorithm for Land (SEBAL) to calculate the evaporation of paleo-lake Chew Bahir's catchment. We also considered the possibility of an additional rainy season during the AHP as previously suggested by numerous studies. The results suggest that an increase in precipitation of 20–30% throughout the southern Ethiopian Rift is necessary to fill paleo-lake Chew Bahir to its overflow level. Furthermore, it was demonstrated that paleo-lake Chew Bahir was highly dependent on the water supply from the upper lakes Abaya and Chamo and dries out within ~40 years if the hydrological connection is cut off and the precipitation amount decreases to present day conditions. Several of such rapid lake level fluctuations, from a freshwater to a saline lake, might have occurred during the termination of the AHP, when humid conditions were less stable. Fast changes in fresh water availability requires high adaptability for humans living in the area and might have exerted severe environmental stress on humans in a sub-generational timescale.https://www.frontiersin.org/article/10.3389/feart.2020.00197/fullAfrican humid periodprecipitation changesabrupt and gradual changesChew BahirLake AbayaLake Chamo |
| spellingShingle | Markus L. Fischer Markus L. Fischer Monika Markowska Monika Markowska Felix Bachofer Verena E. Foerster Asfawossen Asrat Christoph Zielhofer Martin H. Trauth Annett Junginger Annett Junginger Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL Frontiers in Earth Science African humid period precipitation changes abrupt and gradual changes Chew Bahir Lake Abaya Lake Chamo |
| title | Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL |
| title_full | Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL |
| title_fullStr | Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL |
| title_full_unstemmed | Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL |
| title_short | Determining the Pace and Magnitude of Lake Level Changes in Southern Ethiopia Over the Last 20,000 Years Using Lake Balance Modeling and SEBAL |
| title_sort | determining the pace and magnitude of lake level changes in southern ethiopia over the last 20 000 years using lake balance modeling and sebal |
| topic | African humid period precipitation changes abrupt and gradual changes Chew Bahir Lake Abaya Lake Chamo |
| url | https://www.frontiersin.org/article/10.3389/feart.2020.00197/full |
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