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Lake Kivu: Learning from the past for managing its future

Titel Englisch Lake Kivu: Learning from the past for managing its future
Gesuchsteller/in Wüest Alfred
Nummer 123923
Förderungsinstrument Forschungspartnerschaften mit Entwicklungsländern
Forschungseinrichtung Eawag
Hochschule Eidg. Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz - EAWAG
Hauptdisziplin Hydrologie, Limnologie, Glaziologie
Beginn/Ende 01.06.2009 - 31.07.2013
Bewilligter Betrag 453'562.00
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Keywords (4)

Gas-rich lakes; meromixis; methane,; permanent stratification

Lay Summary (Englisch)

Lead
Lay summary
Lake Kivu - Learning from the past for managing its future More information at:http://www.eawag.ch/organisation/abteilungen/surf/kivu/index_ENor martin.schmid@eawag.ch; or flavio.anselmetti@eawag.ch; or alfred.wueest@eawag.ch; Wüest Alfred, Eawag, Kastanienbaum, Switzerland(1) Lead: The 485 m deep Lake Kivu (Rwanda, DR Congo) is a unique aquatic ecosystem: It contains ~60 km3 methane and ~300 km3 carbon dioxide and is permanently density-stratified by salty, carbon dioxide-rich water released by sub-aquatic springs. We aim at locating, sampling and quantifying these deep sources. The drastic changes in sedimentation, which occurred ca 1960, will be investigated for geochemical and biological evidence. The goal is to relate those changes to surface and sub-aquatic inputs, such as nutrients from the catchment.(2) Background: Lake Kivu is among the most fascinating lakes on earth. Almost 1/3 of the inflow occurs not by river tributaries, as in most lakes, but via sub-lacustrine springs. Those springs and their chemical composition affect the lake stratification. Especially, lake-internal nutrient upwelling, algae growths and the subsequent methane production in the deep waters depend on the quantity and quality of the spring flows. Over the centuries, methane has accumulated to an amount, which can be economically exploited, but which also poses a risk to the riparian ~ 2 mio people.(3) Goal: The aim of this project is to locate and sample these sub-lacustrine sources in order to quantify the inflow and the geochemical composition. The external nutrient inputs (with large errors) will be measured with better temporal resolution to calibrate a nutrient catchment model. We also want to complement the observed large changes in sedimentation of inorganic carbon and nutrients with biological variables: The recent history of daphnia and diatoms will be analyzed in ~1 m long sediment cores in order to evaluate whether plankton communities changed parallel to geochemical processes. Furthermore, analyzing a longer sediment core will show whether similar changes occurred before the past 1000 to 2000 years.The project also seeks to improve the research capacities in both countries. The partnership, established with ISP Bukavu during the previous project, will be continued. Currently, we support the Government of Rwanda towards a monitoring group, which should independently monitor methane extraction-related changes in physical, chemical and biological parameters. The present project supports such a capacity.(4) Importance: The results are of scientific interest, as Lake Kivu is among the few large lakes, where sub-aquatic springs define the functioning of the lake. It is of great importance to understand the observed sedimentation changes as a function of the anthropogenic activities (such as fish introduction, catchment, etc) and the relation to the methane production in the lake. Results are also of economic interest: To avoid building-up of the risk of a gas eruption, the two governments have decided to use the methane, worth more than $20 billion. Therefore, it is of great interest to quantify the methane production and the related water constituents (especially nutrients). With this research we envisage to integrate field observations to a previously funded SNF/SDC project on the carbon/methane cycling in Lake Kivu.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Name Institut

Projektpartner

Publikationen

Publikation
Comment on An additional challenge of Lake Kivu in Central Africa – upward movement of the chemoclines by Finn Hirslund
(2012), Comment on An additional challenge of Lake Kivu in Central Africa – upward movement of the chemoclines by Finn Hirslund, in Journal of Limnology, 71(2), 9-13.
Lake Kivu Aquatic Ecology Series Book
(2012), Lake Kivu Aquatic Ecology Series Book.
Local conditions structure unique archaeal communities in the anoxic sediments of meromictic Lake Kivu
(2012), Local conditions structure unique archaeal communities in the anoxic sediments of meromictic Lake Kivu, in Microbial Ecology, 64(2), 291-310.
Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene form the current state of Lake Kivu; East African Rift
, Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene form the current state of Lake Kivu; East African Rift, in Geomorphology.

Zusammenarbeit

Gruppe / Person Land
Formen der Zusammenarbeit
National Museum of Natural History Luxemburg (Europa)
- vertiefter/weiterführender Austausch von Ansätzen, Methoden oder Resultaten
KIST (Kigali Institue of Science and Technology Ruanda (Afrika)
- vertiefter/weiterführender Austausch von Ansätzen, Methoden oder Resultaten
- Forschungsinfrastrukturen
- Austausch von Mitarbeitern

Wissenschaftliche Veranstaltungen

Aktiver Beitrag

Titel Art des Beitrags Titel des Artikels oder Beitrages Datum Ort Beteiligte Personen
EGU General Assembly Vortrag im Rahmen einer Tagung High-resolution bathymetry and sedimentology data from Lake Kivu’s Main Basin reveals morphology and geochemistry controlled by active subaquatic volcanism since the Holocene 07.04.2013 Wien, Oesterreich Ross KellyAnn;
21st Meeting of Swiss Sedimentologists Vortrag im Rahmen einer Tagung Limnic eruption at Lake Kivu: hazard assessment from the analysis of bathymetric and sediment data in ist Main Basin 23.02.2013 Fribourg, Schweiz Ross KellyAnn;
ASLO Aquatic Sciences Meeting Vortrag im Rahmen einer Tagung Subaquatic groundwater discharge sustains the stratification in Lake Kivu preventing the eruption of gas from the deepwater 08.07.2012 Otsu, Japan Ross KellyAnn;
20th Meeting of Swiss Sedimentologists Poster A high resolution bathymetric map of Lake Kivu's northern basin: locating significant groundwater inflows through a geomorphologic interpretation 25.02.2012 Fribourg, Schweiz Ross KellyAnn;
96th Journées Luxembourgeoises de Géodynamique (JLG) Vortrag im Rahmen einer Tagung Mapping Lake Kivu's Northern Basin: A manifestation of seismic stratigraphy and high resolution bathymetry for a 3D perspective 26.10.2011 Luxemburg, Luxemburg Ross KellyAnn;
Research platform on Lake Kivu Vortrag im Rahmen einer Tagung Lake Kivu research activities within the Congo-Rwanda and Swiss institutional framework 11.10.2011 Gisenyi, Ruanda Isumbisho Pascal;
5th International Limnogeology Congress (ILIC) Vortrag im Rahmen einer Tagung The unusual physics of Lake Kivu and its importance for biogeochemical processes and methane exploitation 31.08.2011 Konstanz, Deutschland Wüest Alfred; Ross KellyAnn;
5th International Limnogeology Congress (ILIC) Vortrag im Rahmen einer Tagung The unique geomorphology, geochemistry and archaeal composition of the subaquatic springs that sustain Lake Kivu’s stratification 30.08.2011 Constance, Germany, Deutschland Ross KellyAnn;
19th Meeting of Swiss Sedimentologists Vortrag im Rahmen einer Tagung Seismic stratigraphy and sedimentology of Lake Kivu: a chemically stratified, methane-rich lake 26.02.2011 Fribourg, Schweiz Ross KellyAnn;
7th Workshop on Volcanic Lakes (IAVCEI) Vortrag im Rahmen einer Tagung Lake Nyos and Lake Kivu - two contrasting examples of dangerous gas-rich lakes 10.03.2010 San José, Costa Rica Wüest Alfred;
Tropical Rift Lake Systems: Integrated Volcanologic, Tectonic, and Biogeochemical, and Geohazard Assessment of Lake Kivu Vortrag im Rahmen einer Tagung Methane extraction in Lake Kivu - Structured decision making 14.01.2010 Gisenyi, Ruanda Wüest Alfred;
Tropical Rift Lake Systems: Integrated Volcanologic, Tectonic, and Biogeochemical, and Geohazard Assessment of Lake Kivu Vortrag im Rahmen einer Tagung Mixing and transport processes and their consequences for methane and nutrient cycling in Lake Kivu 14.01.2010 Gisenyi, Ruanda Wüest Alfred;


Veranstaltungen zum Wissenstransfer



Selber organisiert

Titel Datum Ort
Le Lac Kivu: Tirer les leçons de son passé pour gérer son avanir 22.01.2013 Bukavu, Kongo, Demokratische Republik (ex-Zaire)
Lake Kivu: Learning from the past for managing its future 17.01.2013 Kigali, Ruanda

Kommunikation mit der Öffentlichkeit

Kommunikation Titel Medien Ort Jahr
Medienarbeit: Radio, Fernsehen Interviews mit Radiomitarbeitern anlässlich von Workshops in Bukavu und Kigali Radio Okapi, Radio Maendeleo, Radio Isango Star International 2013
Medienarbeit: Printmedien, Online-Medien Medienmitteilung und Interviews mit Zeitungen anlässlich der Workshops in Bukavu und Kigali diverse lokale Zeitungen International 2013
Medienarbeit: Printmedien, Online-Medien Porträt: Eawag-Forschung am Kivu-See Gas, Wasser, Abwasser Deutschschweiz 2012
Medienarbeit: Printmedien, Online-Medien Le lac Kivu «bombe» sous surveillance suisse Le Temps Westschweiz 2011

Verbundene Projekte

Nummer Titel Start Förderungsinstrument
133790 A multibeam-bathymetric device to acquire high-resolution lake floor morphologic data 01.08.2011 R'EQUIP
140538 Lake Kivu - turbulence and double diffusion in permanent stratification 01.04.2012 Projektförderung (Abt. I-III)
122183 Lake Kivu - turbulence and double diffusion in permanent stratification 01.03.2009 Projektförderung (Abt. I-III)
160114 Managing Lake Kivu: moving from a steady-state to a dynamic modelling approach 01.12.2015 Projektförderung (Abt. I-III)
109710 Nutrient cycling and methane production in Lake Kivu 01.01.2006 Resource not found: '20438a61-de74-41e3-9fb1-8132973c4a1f'

Abstract

SummaryLake Kivu is among the most fascinating lakes on earth. Besides the exceptional stratification of dissolved solids and gases, the lake is famous for its methane resources and it is an important nutrition source for the two riparian countries, Rwanda and DR of Congo. To reduce the risk of an eruption and to utilize the methane, the two governments are committed to exploit the methane. First pilot extraction plants are currently under construction and large-scale exploitation is expected in the next years. The fish production in Lake Kivu has increased in the past decades due to the introduction of a Lake Tanganyika sardine. One of the hypotheses links this observation to the recent increase of the in-situ methane production: The introduced fish may have significantly changed the food web and the nutrient cycling. For an optimal methane harvesting strategy and fisheries in the lake, as well as for a reasonable hazard assessment a good understanding of the system is indispensable.Our previous SNF/SDC project allowed to build up a coherent picture of the lake-internal nutrient fluxes and to understand the basic physical processes in the lake. However, the results also shaped the unknown discharge volumes of the sub-aquatic springs as the most relevant uncertainties for predicting the development of the lake under different extraction scenarios. So far the sub-aquatic inflows have been estimated based on model calculations in order to reproduce observed vertical profiles of nutrients and methane concentrations.The present project aims at locating and sampling these sources for an independent estimate of the inflows. The external nutrient inputs, which still carry large errors, need to be measured with a higher temporal resolution to build and calibrate a model for the nutrient inputs from the whole catchment. In addition, we want to complement the observed recent large changes in the sedimentation rates of dissolved inorganic carbon and nutrients with biological variables: The recent history of Daphnia and diatoms will be analyzed in short (~2 m) sediment cores in order to evaluate whether the plankton communities changed at the same time as the geochemical processes. Furthermore, analyzing a longer sediment core will show whether changes similar to the recent ones have occurred before the past 1000 to 2000 years, which cover the build-up-time of the methane.Besides the scientific aims, the proposed project seeks to improve the local research capacities in both countries. Currently, we support the Government of Rwanda towards a monitoring group, which should, in the future, independently monitor methane extraction-related changes in physical, chemical and biological parameters in Lake Kivu. Such a long-term monitoring program can only be effective if it is accompanied by local research activities. The present project contributes to such monitoring capacity, as the identification of the deep sub-aquatic sources requires similar abilities as the monitoring of the discharge of the methane-depleted re-injected water from the deep lake. Nutrient concentrations as well as the plankton communities will have to be monitored in the future to evaluate effects on the bio-geochemical and the biological properties of Lake Kivu.
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