Land-use changes and ever-increasing demands for higher agricultural yields put heavy strains on the Nile basin. Being one of the longest rivers in the world, the Nile is a vital source of fresh water for the entire basin.
“Papyrus wetlands of the upper Nile basin provide water and fertile soils that are essential to sustain agricultural production,” PhD candidate Ellen Jessica Kayendeke says.
However, these areas face intense pressure for conversion to agricultural land.
“The impacts of these changes on wetland functioning and basin wide hydrology are not fully understood.”
Papyrus wetland characteristics
Ellen has spent the past four years studying the papyrus wetlands of the Lake Kyoga basin in Uganda.
“The goal has been to quantify the water storage capacity of a floating papyrus wetland, and understand the seasonal papyrus mat dynamics,” she says.
Furthermore, she has quantified the extent of wetland degradation, and its impacts on vegetation productivity and moisture.
Adapted to wetlands
“Papyrus plants are physically adapted to changing water levels in the wetlands,” Ellen explains.
Their root mat compresses at high water level, which increases the depth of the free water column and storage capacity in the wet season. However, there is declining vegetation moisture and productivity in the catchment area due to land cover changes that occurred more than 15 years ago.
“The wetlands need to be managed in a more sustainable manner to reduce impacts on the groundwater table over a larger area.”
Ellen’s research showed that papyrus wetlands store water.
“This can be quite useful for irrigation of small-scale agriculture,” she says.
She expects an increased interest in the long-term hydrological regime of papyrus wetlands within the Nile basin.
“My work shows that this water storage function can be sustainably utilized to improve agricultural production for the Nile basin countries.”
Ellen has taken hydrometric measurements over a two-year period. Papyrus mat dynamics were assessed by measuring the spatial and temporal changes in the papyrus mat and the water column beneath the mat. The measurements were done for both dry and wet seasons. At the larger scale, she used hyper-temporal image analysis to reconstruct land use history of the study catchment.
Her work is an example of how hyper-temporal image analysis can be utilized for rapid and cost-effective monitoring of impacts of wetland degradation in ungauged catchments of Sub-Saharan Africa.