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Managing Lake Kivu: moving from a steady-state to a dynamic modelling approach

Applicant Schmid Martin
Number 160114
Funding scheme Project funding (Div. I-III)
Research institution Abteilung Oberflächengewässer EAWAG
Institution of higher education Swiss Federal Institute of Aquatic Science and Technology - EAWAG
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.12.2015 - 31.08.2020
Approved amount 320'000.00
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All Disciplines (2)

Discipline
Hydrology, Limnology, Glaciology
Geochemistry

Keywords (6)

mass spectrometry; Lake Kivu; lake modelling; mixing processes; methane; noble gases

Lay Summary (German)

Lead
Der Kivu-See an der Grenze zwischen Ruanda und der Demokratischen Republik Kongo enthält grosse Mengen gelöster Gase. Diese stellen eine Gefahr dar, weil sie einen katastrophalen Gasausbruch aus dem See verursachen könnten. Andererseits ist das gelöste Methan auch eine wertvolle Ressource. Im diesem Forschungsprojekt soll ein numerisches Modell entwickelt werden, mit welchem sich die Folgen der Methangewinnung aus dem Kivu-See besser als bisher abschätzen lassen.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Die heutigen Regeln für die Bewirtschaftung des Kivu-Sees beruhen auf Vorhersagen für die künftige Entwicklung des Sees, die mit einem einfachen, vor einem Jahrzehnt an der Eawag entwickelten Modell gemacht wurden. Inzwischen wurden zahlreiche Messungen im See, seinem Einzugsgebiet und seinen Sedimentablagerungen durchgeführt. Diese erlauben weitreichende Rückschlüsse auf die historische Entwicklung, die Nährstoffkreisläufe und die Quellen und Senken der gelösten Gase im See. welche bei der Entwicklung des neuen dynamischen Modells mit einfliessen werden. Als zusätzliche Grundlage für die Modellierung werden mit einem neu an der Eawag entwickelten Messgerät die Konzentrationen verschiedener Gase im See gemessen. Dabei handelt es sich einerseits um Spurengase, welche Rückschlüsse auf die langfristigen Transportprozesse innerhalb des Sees erlauben, andererseits um die für die Bewirtschaftung des Sees zentralen Gase Methan und Kohlendioxid.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Das in diesem Projekt entwickelte Modell wird eine zuverlässigere Abschätzung der Konsequenzen verschiedener Szenarien für die Nutzung des Methans im Kivu-See erlauben. Es wird auch ermöglichen, eine bessere Vorstellung über die Entwicklung des Sees im letzten Jahrtausend zu gewinnen. Die im Projekt entwickelte Methode zur Messung der Gaskonzentrationen im See ist zudem ein vielversprechender Ansatz für eine zuverlässiges Langzeit-Monitoring der Gaskonzentrationen im Kivu-See.

Direct link to Lay Summary Last update: 24.04.2015

Responsible applicant and co-applicants

Employees

Name Institute

Project partner

Publications

Publication
No increasing risk of a limnic eruption at Lake Kivu: Intercomparison study reveals gas concentrations close to steady state
Bärenbold Fabian, Boehrer Bertram, Grilli Roberto, Mugisha Ange, von Tümpling Wolf, Umutoni Augusta, Schmid Martin (2020), No increasing risk of a limnic eruption at Lake Kivu: Intercomparison study reveals gas concentrations close to steady state, in PLOS ONE, 15(8), e0237836.
Missing atmospheric noble gases in a large, tropical lake: The case of Lake Kivu, East-Africa
Bärenbold Fabian, Schmid Martin, Brennwald Matthias S., Kipfer Rolf (2020), Missing atmospheric noble gases in a large, tropical lake: The case of Lake Kivu, East-Africa, in Chemical Geology, 532, 119374-119374.

Collaboration

Group / person Country
Types of collaboration
Bertram Boehrer, Department Lake Research, Helmholtz Centre for Environmental Research - UFZ Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Roberto Grilli, Institut des Géosciences de l’environnement France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Augusta Umutoni, Rwanda Energy Development Corporation Ltd. (EDCL) Rwanda (Africa)
- in-depth/constructive exchanges on approaches, methods or results
Werner Aeschbach, Institute of Environmental Physics, University of Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EGU General Assembly 2019 Talk given at a conference Noble gas profiles from Lake Kivu: Where have the atmospheric gases gone? 07.04.2019 Vienna, Austria Bärenbold Fabian;
Physical Processes in Natural Waters Poster On-site analysis of gas concentrations in Lake Kivu, Central Africa 20.08.2018 Solothurn, Switzerland Bärenbold Fabian;
Goldschmidt Conference Poster On-Site Analysis of Gas Concentrations at Lake Kivu, Central Africa 13.08.2017 Paris, France Bärenbold Fabian;
International Congress on Environmental Modelling and Software (iEMSs) Talk given at a conference Methane extraction from Lake Kivu: a case study for model-based policy 11.07.2016 Toulouse, France Schmid Martin;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Kivu gas study validation workshop Workshop 10.12.2018 Nyamata, Rwanda Schmid Martin; Bärenbold Fabian;
Assessment of the Intercalibration Campaign for Gas Measurements in Lake Kivu Workshop 22.05.2018 Magdeburg, Germany Schmid Martin;
Third International workshop on Monitoring and Development of Lake Kivu Gas Resources Workshop 29.05.2017 Kigali, Rwanda Schmid Martin;
Workshop of the Lake Kivu Monitoring Program Workshop 27.01.2017 Kigali, Rwanda Bärenbold Fabian; Schmid Martin;


Associated projects

Number Title Start Funding scheme
109710 Nutrient cycling and methane production in Lake Kivu 01.01.2006 Resource not found: 'bd31932a-e257-46d9-9dba-079f6f2c77c6'
132155 Noble-gas and fluid transport processes in lake sediments 01.09.2011 Project funding (Div. I-III)
140538 Lake Kivu - turbulence and double diffusion in permanent stratification 01.04.2012 Project funding (Div. I-III)
123923 Lake Kivu: Learning from the past for managing its future 01.06.2009 Resource not found: 'bd31932a-e257-46d9-9dba-079f6f2c77c6'

Abstract

Methane (CH4) extraction from Lake Kivu is a high priority for the Governments of Rwanda and the Democratic Republic of the Congo (DRC) for two reasons: (i) the large amounts of gases stored in the lake could, if they would erupt, create a natural disaster with unimaginable consequences, and (ii) the CH4 is a valuable energy resource for both bordering countries. The management strategies for the CH4 exploitation of the lake currently rely to a large extent on simulations made with a 1-dimensional lake model developed by Eawag a decade ago. This model was used to predict the long-term development of the stratification as well as concentrations and fluxes of nutrients in the lake for different CH4 extraction scenarios. However, the model was based on a limited amount of data and relied on the assumption that the lake is currently near steady-state. With the proposed project, we aim at developing a new transient model for Lake Kivu that considers the dynamic properties of the lake. The model will be used to (i) derive a range of possible scenarios for the history of the lake in the last 1000 years that has led to the present conditions, (ii) estimate the most probable development of the lake in the future for selected CH4 extraction scenarios under a range of different climatic conditions, and (iii) assess the contributions of the CH4 extraction, the hydrological processes and climatic conditions on the uncer-tainty of these projections. The development of the new model relies on novel measurement and modelling techniques that have emerged in the last decade and will be further advanced during this project, as well as on the availability of observational data from preceding research projects on Lake Kivu. For the purpose of quantify-ing the transport and mixing processes in the lake based on geochemical data, our successful 1-dimensional phys-ical lake model Simstrat will be coupled via the recently developed Framework for Aquatic Biogeochemical Mod-els (FABM) to the Aquatic EcoDynamics Modelling Library (AED) of the University of Western Australia. The new coupled model will allow a flexible calibration of the transport processes with various geochemical tracers.The already available data includes detailed investigations of the physical and geochemical properties of the water column and the subaquatic groundwater sources feeding the lake, and new findings on the historical development of the lake from paleolimnological studies. These data will be complemented in the present project with vertical profiles of the concentrations of dissolved gases (noble gases, CH4, carbon dioxide) in the lake. For this purpose, the portable field mass-spectrometer which was recently developed at Eawag will be adapted to allow vertical profiling in deep lakes. The newly acquired gas measurements will enable us to better constrain the vertical transport processes between the deep water and the near-surface water and to quantitatively assess the influence of the subaquatic groundwater discharge on the lake-internal processes. Furthermore, this method is a promising candidate for consistent and accurate measurements of the concentrations of dissolved CH4 in the lake, which are indispensable for managing the CH4 resource.
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