Hydrodynamics of The Fluids In Gisenyi-Hot Springs Area (rwanda) In Relation To Geothermal Potential

The Gisenyi hot springs area is located on the North -Western coastline of Lake Kivu, in the Kilwa peninsula area, NW Rwanda in the western arm of the Great Easter African Rift System. It is one of the few surface thermal manifestations in Rwanda. The hot springs display a maximum surface temperature of around 73 0C that varies with seasons. The fluid chemistry reveals the water from hot springs to be classified as Na-HCO3- water type with near neutral pH value. The Lake Kivu, where hot springs occur, is an ancient lift lake situated between Rwanda and the Democratic Republic of the Congo with a maximum depth of 485 m. The lake contains dissolved carbon dioxide and methane gases forming permanent stratified layers in deep water. Some researchers have attributed the origin of CO2 to be from magmatic or mantellic sources and therefore to be related to active volcanism beneath lake bottom. The inflows from hydrothermal springs are considered to maintain the stratification of the lake that display higher temperature and higher dissolved content in the lower layer. Water and gas samples from hot springs, Lake Kivu and nearby boreholes have been collected for further chemical and isotopic analysis to understand the fluid movement and heat source of the geothermal system in the Gisenyi area. The fractured pegmatite linked to the deep seated granite was identified as a possible geothermal reservoir. This paper discusses any connection between Lake Kivu water composition, thermo-fluid activity and the surface hot springs. Together with geological data, this should contribute to a better evaluation of the geothermal resource potential of the Kilwa peninsula area