Preprints
https://doi.org/10.5194/esd-2020-36
https://doi.org/10.5194/esd-2020-36
08 Jul 2020
 | 08 Jul 2020
Status: this preprint was under review for the journal ESD but the revision was not accepted.

Simulating Lake Tanganyika's hydrodynamics under a changing climate

Kevin Sterckx, Philippe Delandmeter, Jonathan Lambrechts, Eric Deleersnijder, and Wim Thiery

Abstract. Lake Tanganyika is the second oldest (oldest basin of the lake is 9–12 million years old), second deepest (1470 m) lake in the world. It holds 16 % of the world's liquid freshwater. Approximately 100 000 people are directly involved in the fisheries operating from almost 800 sites along its shores. Despite the vital importance of Lake Tanganyika and other African inland waters for local communities, very little is known about the impacts of future climate change on the functioning of these lacustrine systems. This is remarkable, as projected future changes in climate and associated weather conditions are likely to influence the hydrodynamics of African water bodies, with impacts cascading into ecosystem functioning, fish availability and water quality. Here we project the future changes in the hydrodynamics of Lake Tanganyika under a high-end emission scenario using the 3D version of the Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM 3D) forced by a highresolution regional climate model. We first show the added value of 3D simulations compared to previously obtained 1D model results. The simulated interseasonal variability of the lake with this 3D model explains how the current mixing system works. A short-term present-day simulation (10 years) shows that the 75 m deep thermocline moves upward in the south of the lake until the lower layer reaches the lake surface during August and September. Two 30-year simulations have been performed (one with present day and one with future conditions), such that a comparison can be made between the current situation and the situation at the end of the 21st century. The results show that the surface water temperature increases on average by 3 ± 0.5 K. The latter influences the hydrodynamics in the top 150 m of the lake, namely the bottom of the thermocline does not longer surface. This temperature-induced stratification fully shuts down the earlier explained mixing mechanism.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Kevin Sterckx, Philippe Delandmeter, Jonathan Lambrechts, Eric Deleersnijder, and Wim Thiery
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Kevin Sterckx, Philippe Delandmeter, Jonathan Lambrechts, Eric Deleersnijder, and Wim Thiery
Kevin Sterckx, Philippe Delandmeter, Jonathan Lambrechts, Eric Deleersnijder, and Wim Thiery

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Short summary
This work covers multiple 3D simulations of the hydrodynamics of Lake Tanganyika, covering the inter-seasonal variations and the evolution linked to climate change. The research was done with COSMO-CLM2 data, which was used to run the SLIM 3D Lake Tanganyika model. The main results explain how this stratified lake can still maintain a certain mixing between the different layers, but how this would come to an end due to climate change.
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