2014TEBBSEJPhD.pdf (9.86 MB)
Remote sensing for the study of ecohydrology in East African Rift lakes
thesis
posted on 2014-06-16, 13:16 authored by Emma Jayne TebbsThis thesis investigates remote sensing as a tool for monitoring the ecohydological
sustainability of alkaline-saline lakes in the East African Rift
Valley, of critical importance to Lesser Flamingos (Phoenicopterus minor).
In Lake Bogoria, an algorithm was developed for retrieving chlorophyll-a as
an indicator of cyanobacterial biomass - the Lesser Flamingos' primary food
source. Results showed a strong linear relationship between Chl-a and the
top-of-atmosphere Landsat ETM+ band ratio R[subscript 835]=R[subscript 660] (R[superscript 2] = 0.801; SE = 70 µg l[superscript -1]); valid for Chl-a up to 800 µg l[superscript -1]. At Lake Natron, the sole
breeding site for Lesser Flamingos in East Africa, breeding is hydrologically
dependent. Landsat-derived lake surface area estimates and ground-based
observations of
flamingo breeding showed that breeding takes place on a receding
lake level. Upper and lower limits for which breeding is feasible were
de fined (700-750 km[superscript 2] and 150-180 km[superscript 2] respectively) based on the presence
of islands in Landsat imagery.
Extending to a regional scale, a Landsat-based optical classi fication scheme
was developed for alkaline-saline lakes; the scheme was able to distinguish
six classes with a classifi cation accuracy of 73% when verifi ed against in
situ measurements. Classifi ed imagery showed the potential importance to
flamingos of the food resources off ered by Lake Logipi. Long-term timeseries
of Chl-a and other environment variables for Lake Bogoria, from satellite
datasets, showed that direct rainfall and lake levels were both weakly related
to Chl-a and between them accounted for 20% of the variance in Chl-a.
Examination of Landsat imagery showed common features associated with
cyanobacterial bloom collapse in Lake Bogoria, which suggested three plausible
explanations for these events. Hence, the results of this thesis have improved
understanding of the connections between ecological and hydrological
processes in alkaline-saline lakes and the role these lakes play in supporting
the Lesser Flamingo species.
History
Supervisor(s)
Harper, David; Remedios, JohnDate of award
2014-06-01Author affiliation
Department of Physics and AstronomyAwarding institution
University of LeicesterQualification level
- Doctoral
Qualification name
- PhD
Language
enAdministrator link
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