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UNESCO-IHE Institute for Water Education, Delft (2019)

Greenhouse gas emissions from rivers in Taita Hills, Kenya

Gubamwoyo, Sharon

Titre : Greenhouse gas emissions from rivers in Taita Hills, Kenya

Auteur : Gubamwoyo, Sharon

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2019

Résumé partiel
Head water streams (HWS) are thought to play a disproportionate role in inland aquatic greenhouse gas (GHG) emissions due to their close relationship with the watershed and the role of the benthic zone in biogeochemical processes responsible for GHG emissions. The contribution of headwater streams at catchment scales, however, has rarely been quantified. Furthermore, land use, in addition to stream order may also play a role in GHG emissions. Little is known about GHG emissions from tropical systems, including sub-Saharan Africa, where land use change is occurring rapidly, in part due to agricultural intensification. Furthermore, the seasonality, particularly with respect to rainfall, may be important, but has not been fully explored. Land use and rain events may create hot spots and hot moments of GHG emissions. Therefore, this study explored the GHG (CO2, CH4, and N2O) concentrations, fluxes and gas transfer velocities in the Taita Hills region in south eastern Kenya. Two different catchments were studied (Bura and Wundanyi) with a total of 48 sampling points, across 6 stream orders and different land use types, from forest, mixed, and agriculture. I further intensively surveyed two headwater sub-catchments in the main catchments mentioned above at 5 m intervals during a wet and dry period to understand how stream width is related to GHG flux, resulting in 600 sites in the Bura catchment and 800 sites in the Wundanyi catchment. These measurements were then used in a simple up-scaling calculation to sub-catchment level to compare the two catchments and moisture conditions.

Sujets  : greenhouse gas emission catchments land use change biogeochemical processes Kenya


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