A dissertation submitted to the Faculty of Science, University of the
Witwatersrand, in fulfilment of the requirements for the Degree of Master
of Science. Johannesburg, 20 January 2017. / Sand dune movements can be effectively monitored through the comparison of multitemporal
satellite images. However, not all remote sensing platforms are suitable to
study sand dunes. This study compares coarse (Landsat 7 and 8) and fine (Worldview
2) resolution platforms, specifically focussing on sand dunes within the Ubārī Sand Sea
(Libya), and identified the average migration rate and direction for the linear dunes
within a section of the Ubārī sand sea for the time period from 2002-2015 with the use
of Landsat imagery.
Two band combinations were compared with the use of two supervised classifications.
The best combination was found to be red, green, blue and near-infrared band
combination and the maximum likelihood classifier.
The dune features, namely the crest, slope and interdunal areas were successfully
classified based on both the coarse and fine resolution imagery, but the accuracy with
which it can be classified are different between the two resolutions. The classifications
based on the Worldview 2 imagery had overall accuracies ranging from 55.43 - 60.83%
with kappa values of 0.3486 – 0.4225 compared to the overall accuracies and kappa
values of the classifications based on the Landsat 8 imagery ranging from 52.11 –
64.67% and 0.3878 – 0.4927 respectively. An average migration rate of 8.64 (± 4.65)
m/yr in a generally north western direction was calculated based on the analysis of
remote sensing data with some variations in this rate and the size and shape of the
dunes.
It was found that although Worldview 2 imagery provides more accurate and precise
mensuration data, and smaller dunes identified from Worldview data were not
delineated clearly on the Landsat imagery. Landsat imagery is sufficient for the studying
of dunes at a regional scale. This means that for studies concerned with the dune
patterns and movements within sand seas, Landsat is sufficient. In studies where the
specific dynamics of specific dunes are to be selected, a finer resolution is required;
platforms such as Worldview are needed in order to gain more detailed insight and to
link the past and present day climate and environmental change. / MT2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22732 |
| Date | January 2017 |
| Creators | Els, Anja |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (xi, 132 leaves), application/pdf |
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