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@PHDTHESIS{Drwald:1002599,
author = {Dörwald, Lukas},
othercontributors = {Lehmkuhl, Frank and Stauch, Georg and Yang, Xiaoping},
title = {{D}unes influenced by climate change : remote sensing
observations from the northeastern {T}ibetan {P}lateau},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2025-00563},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2025; Dissertation, Rheinisch-Westfälische
Technische Hochschule Aachen, 2024},
abstract = {Climate changes are an ongoing process around the globe.
One of the most vulnerable areas are drylands.
Desertification is widely reported in most of these areas
and is of particular research interest due to its influence
on human infrastructures and habitat, as drylands are home
to approximately $40\%$ of the human population. The extent
of global drylands fluctuates since the 1940s with a general
increase, peaking in the period of 1980-2008 with $3.1\%$
increase relative to 1948-1979 (Li et al., 2019). Under
different scenarios of global warming, arid and semi-arid
areas could potentially expand up to $7-12\%$ in size
effecting more people by the year 2100 (Feng and Fu, 2013;
Koutroulis, 2019; Yao et al., 2020). One of the most common
geomorphic features in arid and semi-arid environments are
dunes. They show fast reaction times to changes in local
climatic conditions and have been used to study and
reconstruct short- and long-term climatic changes by
multiple researchers. The northeastern Tibetan Plateau (TP)
is widely regarded as the third pole and holds a unique
regional configuration of high elevation and varying
topography. For humans and other lifeforms, the TP is of
high importance due to its role as a water source, feeding
multiple large river networks, including the Yangtze, the
Yellow River, the Indus, and the Ganges. The main wind
regimes are the mid-latitude Westerlies, dominant in the
winter months, and the East Asian Summer Monsoon (EASM).
This combination results in extreme seasonality with dry,
cold, and windy winters and rainy, mild summer months. Dunes
are landscape features which are widely distributed among
the northeastern TP. Sand sources are manifold with erosive
sediment from mountain processes to fluvial material being
blown out. However, dune specific studies with a recent time
focus are still scarce on the northeastern TP. Also, the
study of a high number of individual dunes in relation to
wind derived values for their exact position is not that
common. The main dune type found in the study areas are
barchan dunes, both in dune fields and solitary. The
presented thesis aims to analyze dune migration rates, dune
field density, and sand sheet area development on the
northeastern TP in relation to climate changes of the past
six decades. Dune migration rates as the main metric, as
well as dune field density are extracted from multitemporal
satellite imagery observation. A key data source to achieve
this task are the CORONA KH-4B satellite images from the
1960s. They have a sufficiently high spatial resolution of
up to 1.8 m making identification of singular barchan dunes
possible. Wind information is mainly extracted from the
ERA-5 reanalysis dataset (30 km spatial resolution) in order
to cover the given time period. Here, drift potential and
related indices are calculated, analyzed and compared to the
selected dunes spatially and temporarily. These datasets are
completed with ERA5-Land reanalysis data (9 km spatial
resolution) for temperature and precipitation, and
Normalized Difference Vegetation Index (NDVI) from Landsat
5, 7, and 8 images since 1987. Upon the broad northeastern
TP, three focus regions were chosen, as well as one at the
northern margin to get comparative data across the region,
and the neighboring areas. Though the three presented
studies the results show a good correlation between dunes as
actual landscape features and climate model data,
represented by ERA-5. However, regional contrasts become
apparent in terms of dune migration rates, where the
influence of the main wind regimes are dominant. It was
found, that the Westerlies, still the dominant driver for
aeolian transport, are weaker in the summer months, while
dominant in winter. This north-to-south gradient is well
represented in the migration rates of 563 mapped and
measured barchan dunes across the northeastern Tibetan
Plateau, a big repository of dune movement data. Also, where
the EASM is more influential, hardly any barchans are found.
Further, human impact was considered and is found to alter
natural development measurable as presented by dune field
density data in agricultural areas.},
cin = {551610 / 530000},
ddc = {550},
cid = {$I:(DE-82)551610_20140620$ / $I:(DE-82)530000_20140620$},
pnm = {BMBF 01LP2003A - Klimaforschung mit China - Dünen als
Indikator für den Klimawandel in Zentralasien (DUNE)
(01LP2003A)},
pid = {G:(BMBF)01LP2003A},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2025-00563},
url = {https://publications.rwth-aachen.de/record/1002599},
}
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