Geomorphology 42 (2002) 183 – 195
www.elsevier.com/locate/geomorph
Geomorphology of sand dunes in the Northeast
Taklimakan Desert
Xunming Wang a,*, Zhibao Dong a, Jiawu Zhang b, Guangting Chen a
a
Laboratory of the Blown Sand Physics and Desert Environments, Cold and Arid Regions Environmental and Engineering Research
Institute, Chinese Academy of Sciences, Lanzhou 730000, China
b
Department of Geography, Lanzhou University, Lanzhou 730000, China
Received 5 September 2000; received in revised form 28 March 2001; accepted 29 March 2001
Abstract
Three types of sand dunes exist in the Taklimakan Desert, namely compound/complex crescent dunes and crescent chains,
compound dome dunes and compound/complex linear dunes. Besides these three compound/complex types, single simple
dunes are also distributed throughout the sand sea. The compound/complex linear dunes are developed under acute bimodal
wind regimes. Though the ratios of the resultant drift potential (RDP) and the drift potential (DP) are the same as that near the
border and adjacent area of the sand sea, the compound/complex crescent and dome dunes are developed, respectively, because
of divergence of the sand available, the stress of the sand-moving winds and the time scales of dune formation. The sand supply
for the dunes is not from Lopo Nor in the east as previous studies suggested but mainly from local alluvial or lacustrine
deposits. The grain size component does not correlate evidently to the morphology parameters of the sand dunes. Analyses of
the DP and drift direction suggest that the northeast Taklimakan is an area of low wind energy and the resultant drift direction
(RDD) coincides well with the distribution, morphology and scales of the dunes. D 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Sand dunes; Taklimakan Desert
1. Introduction
The Taklimakan Desert lies in the Tarim Basin in
the northwest part of China, with an area of
33.8 104 km2 accounting for 50% of the total area
of sandy deserts in China (Zhu and Chen, 1994). As
the largest active desert in China and the second
largest in the world (Zhu, 1980), it is the centre of
dust storms in China and one of the main source areas
*
Corresponding author.
E-mail address: [email protected] (X. Wang).
for Chinese loess deposits (Zhang, 1984). The Taklimakan Desert has been famous since ancient times for
the magnificent sand dunes of all types, abundant
cultural relics in the desert and the ‘‘Silk Road’’
passing through both the north and the south margins
between the desert and the mountains, attracting many
explorers (e.g. Hedin, 1896; Heidin, 1905) to make
investigations and explorations in the desert. Scientific research on this desert, however, has been limited
compared with other large sand seas in the world.
There have been some studies on the Taklimakan
Desert since the 1960s but only in the outer areas
(Zhu et al., 1981; Zhu, 1984; Wu, 1981; Zhou, 1995)
0169-555X/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 9 - 5 5 5 X ( 0 1 ) 0 0 0 8 5 - X
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X. Wang et al. / Geomorphology 42 (2002) 183–195
due to the inaccessibility of the interior of the sand
sea, or by means of remote-sensing (e.g. Breed et al.,
1979; Zhu, 1984; Mainguet and Chemin, 1986; Ishiyama et al., 1996), resulting in little preliminary
knowledge of the central part of the desert.
With the exploration and exploitation of the oil and
natural gas in the Tarim Basin in recent years, the
environment and the morphology of all types of sand
dunes in the interior of the desert have been described
(Wang et al., 1997; Chen, 1993; Chen et al., 1996);
however, the desert is still far from being understood.
Specifically, there is almost no research done in the
northeast of the sand sea, one of the areas in which the
morphology of the dunes is most complicated (Zhu,
1980; Zhu et al., 1981). In addition, the Taklimakan
Desert is expanding into the adjacent areas especially
in the east almost reaching the other desert—Kumtag.
The geomorphological study of the sand dunes in the
northeast area is of great importance in understanding
the wind activities and the dynamics of dune formation.
Here, we present the results of detailed investigations in the field and the morphologic analyses on the
dunes with the 1:25,000 aerial photographs and the
1:100,000 topographic maps covering the northeast
Taklimakan Desert. According to the distribution of
different typical types of dune, we selected some
typical sampling areas for detailed analysis, mapped
the dune crest lines and a series of morphological
properties with the aerial photographs. Eight morphological properties were recorded for each dune type:
the average length, width, height of the dune, the
spacing and the junctions between dunes, the lengths
of the windward and the leeward slopes of the dune,
and the trends or the advance directions of the dunes.
For compound/complex crescent dunes, we chose four
typical sampling sites. For compound/complex domeshaped and linear dunes, two and three sampling sites
were selected, respectively. The morphologies of
simple linear dunes were obtained through detailed
investigations in the field. The meteorological data
have been gathered in the area with different morphologies of the dunes (Xiaotang, Mancan and Tazhong). Sand samples from 34 dunes of different types
in the field were sieved at quarter-phi intervals for
grain-size analysis. The data on the thickness of the
Quaternary sediments in northeast Taklimakan Desert
are from the Department of Geological Prospecting in
Tarim Basin.
2. Regional environment
The Northeast Taklimakan is defined as in Fig. 1 in
this paper. It lies between 83°E (about 100 km to the
east of River Keliya) and the east boundary of Tarim
Basin and 39°N (50 km to the south of central Tarim)
to 41°N (mid-lower reaches of River Tarim). As the
Tarim Basin slopes from the southwest to the northeast, the northeast part of the desert has an average
elevation of 1100 m and is surrounded by mountains
in the south, west and north with a ‘passage’ of about
70 km in the east.
It is an extremely arid area. Meteorological data
(1992 – 1998, averaged) show that the mean annual
precipitation at the northeast edge is 100 mm and
decreases to 50 mm in the central desert, mainly
concentrated in April to June in several intense rainfall events (Fig. 2a). The climate is affected by the
Tibet Plateau and the Tarim Basin landforms (Ling,
1988). It is controlled mainly by a high-pressure
system above the northeast Taklimakan in the summer. The near ground convergent line is near the
River Keliya at a height of 300 m. A subtropical high
controls the area over 400 m. Above 5000 m, however, it is completely controlled by the west wind
belts. In winter, the whole area is under a highpressure system centered at 40°N, 83°E with a nearground air flow line converging in River Keliya
region (Li et al., 1990). Fig. 2a and b shows that
both the average monthly temperatures and wind
velocities increase or decrease in phase. The sandmoving winds mainly occur in spring and summer
(April –August), and the main directions are N near
the border of the desert and E in the centre of the
desert.
3. Morphology of sand dunes
The dune types in the northeast are complicated
and all types can be found from the south to the north.
Fundamentally, they are classified to three main types
according to McKee (1979): (1) simple, compound or
complex crescent dunes and chains near the border of
the desert; (2) compound and complex dome-shaped
dunes and (3) compound and complex linear dunes in
the interior of the desert. The distribution of these
types of dune is illustrated in Fig. 1. Besides these
X. Wang et al. / Geomorphology 42 (2002) 183–195
Fig. 1. Geomorphological map of the northeast Taklimakan Desert. The symbols A to I indicate the locations of Fig. 3 – 6 in this figure.
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X. Wang et al. / Geomorphology 42 (2002) 183–195
Fig. 2. Annual distributions of: (a) Mean precipitation, (b) Mean wind velocities, and (c) Mean temperatures (1992 – 1998, averaged). The
meteorological stations of Xiaotang, Mancan and Tazhong are presented and correspond to the positions identified in Fig. 1.
three types, few scattered parabolic dunes and shrub
dunes are also distributed in the area.
3.1. Compound and complex crescent dunes and
chains near the border of the desert
These are distributed mainly between the northern border and about 50 km to the south on the
alluvial plain or former riverbeds of the River
Tarim. The remains of the paleo-riverbeds are clear
and some simple crescent dunes have formed in
them. The compound and complex crescent chains
develop in association with the paleo-riverbeds.
They are divided into three types in distribution:
single ones, chain-shaped ones and coalescing
chains (Fig. 3a – d). The average trend is NW –SE.
The chains are 8 –15 m high, 200 –600 m wide and
2 –5 km long on average with a maximum length of
7 –8 km. There are no obvious slip faces. Some
small subcrescent dunes develop on the windward
side which are usually 10– 20 m wide with a lee
slope of 2 –3 m. The spacing of the chains of the
crescent dunes is about 100 – 400 m, and between
the interdunes of the compound and complex cres-
cent chains, there are also some other types of dune
such as small crescent dunes, sand ridges and shrub
dunes.
3.2. Compound and complex dome-shaped dunes near
Mancan
This type of dune is distributed mainly within a 25km-wide area from 15 km to the north and 10 km to
south of Mancan where the underlying landforms are
the oldest alluvial or flood plains of the River Tarim.
Most of the dunes have round to oval plan forms with
no slip faces. They are aligned of SW –NE. The dune
height varies from 20 to 60 m and length from 200 to
900 m. Dense clusters of crescent dunes have developed on the domes, spreading from random to regular
chains in a NE – SW direction with the increase in size
of these dunes. The spacing of the dunes is about
200– 600 m (Fig. 4). In the interdune areas between
these domes, there are also some sand ridges, small
crescent dunes and shrub dunes. The sand ridges
range from 50 to 500 m in length but are lower than
1 m in height. The crescent dunes are usually lower
than 2 m.
X. Wang et al. / Geomorphology 42 (2002) 183–195
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Fig. 3. Distributions of the compound and complex crescent dunes and chains. (a) Single, (b) Chain-shaped, (c) Coalescing chains, and (d)
Aerial photographs. Four locations (a, b, c and d) are presented and correspond to the positions identified in Fig. 1 for the symbols A, B, C and
D respectively.
3.3. Compound and complex linear dunes in the
interior of the desert
Dunes of this type are distributed in the area
between 10 km to the south of Mancan and Minfeng.
There is some controversy on the classification of this
type of dune. Earlier studies by Chinese scientists
attributed them to compound crescent chains (Zhu et
al., 1981), but further investigations reveal that these
dunes have the morphological characteristics of linear
dunes.
3.3.1. Simple linear dunes
Simple linear dunes are found in almost every part
of the Taklimakan desert but are relatively concentrated in the interdune areas in the zones of the
compound and complex linear dunes. In the central
part of the desert, simple linear dunes vary from 200
to 2000 m in length, 3 to 5 m wide in the front end and
5 to 10 m wide in the middle and the posterior. The
average trend is NE45 –60° with an acute angle of
10 –15° to the compound dunes. The spacing between
the simple linear dunes is about 10 –30 m and they are
nearly parallel to the resultant drift direction (RDD).
The crest lines are slightly curved and the transectional shape is asymmetric. The west sides are 3 – 6 m
lengths and the east sides are about 2 m in length at
the front. At the posterior, however, both slopes are
similar (about 2 m) with a symmetric shape but this
varies frequently according to changes in the wind
direction during the windy season, as the crest lines
move to and fro and the lee sides appear on both
slopes of the dunes (Fig. 5). There are no subdunes on
the slopes. Simple linear dunes in other parts of the
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X. Wang et al. / Geomorphology 42 (2002) 183–195
Fig. 4. Distributions of compound/complex dome-shaped dunes. The location of the aerial photograph is presented and corresponds to the
positions identified in Fig. 1 for the symbol E.
Fig. 5. The landscape of a simple linear dune. The dune is about 1800 m in length. The photo was taken in the middle of the dune, and the left
side is west. The location of the photograph is presented and corresponds to the position identified in Fig. 1 for the symbol F.
X. Wang et al. / Geomorphology 42 (2002) 183–195
basin have similar morphology but with different
trends where the RDD changes.
3.3.2. Compound/complex linear dunes
Compound/complex linear dunes are concentrated
mainly in this area which accounts for 70% of the total
area of linear dunes in the Taklimakan sand sea, and
they have the most complicated morphology. Basically, there are two types of distribution patterns for
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the complex linear dunes: longitudinal forms or longitudinal but with coalescence among them (Fig. 6).
The height of the dunes increases from 30 to 70– 100
m from the north to the centre of the desert and the
length also increases when the morphology becomes
more complicated. The average trend of the dunes in
this area is N50°E –N60°E. Though both sides act as
the windward slope alternately, the duration when the
east side is the windward slope is usually longer than
Fig. 6. Distribution of the compound/complex linear dunes. (a) Longitudinal forms, (b) Longitudinal forms but with coalescence among them,
and (c) Aerial photograph. Three locations (a, b, and c) are presented and correspond to the positions identified in Fig. 1 for the symbols of G, H
and I, respectively.
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X. Wang et al. / Geomorphology 42 (2002) 183–195
that of the west side during the windy season. Dense
crescent chains and some separate star-shaped or
dome-shaped dunes develop on the NE slope. They
are 5 – 8 m high and 30– 50 m wide with windward
slope of 20 –80 m in length and obvious slip faces of
9 – 20 m in length. There are angles of 10 – 30°
between the trends of these subdunes and the main
compound dunes. Subdunes on the southwest side are
lower and are confined to a 250-m-wide zone below
the crest line. They are parallel or less than 10° to the
compound dunes. The length of the complex dunes
usually ranges from 4 to 10 km and the east side is
800 –1500 m wide with low slopes from 1 –2° near
the interdune corridor to 8– 10° near the crest. The
west side, however, is normally narrower than 250 m
with steep slopes of 10 – 20°. The compound/complex
dunes are roughly parallel to each other and are
slightly curving in trend (Fig. 6a,c). Some complex
linear dunes are longitudinal forms but there is coalescence among them making them look like ‘‘Y’’s or
‘‘H’’s (Fig. 6b). The spacing is 800– 3000 m wide and
in the interdunes some small ridges or crescent dunes
are developed which are moving downwind with
angles of less than 10° to the RDD. The angles
between the simple linear dunes in the interdune
corridors and the compound ones change from 10–
20° in the north to 30 – 45° in the south.
4. Factors that control the morphology
4.1. Grain size components
Considerable attention has been paid to the development and interpretation of statistical parameters of
the size and sorting of dune sands (Lancaster, 1995).
For a single dune, the surface grain size composi-
tions have apparent difference (e.g. Watson, 1986;
Livingstone, 1987). For the whole sand sea, however, the relationship between the grain size components and the morphology and scale of the dunes has
been controversial (Wilson, 1973; Thomas, 1988;
Lancaster, 1995). As far as the grain size components
in the northeast Taklimakan are concerned, some
difference does exist in the three different areas of
dune types (Table 1). The mean grain size of dune
sand near the border of the desert where the compound/complex crescent chains develop is 2.10 –
3.20/ (0.223 – 1.109 mm), In contrast, the mean
grain sizes in the areas of dome-shaped dunes and
compound linear dunes are 3.25 – 3.40/ (0.105 –
0.094 mm) and 3.10 – 3.60/ (0.117 – 0.082 mm),
respectively. Compared with the grain size in the
other sand seas (Lancaster, 1995), it appears that the
Taklimakan has some of the finest sands in the
world’s sand seas. Two potential factors may have
controlled the processes during which the mean grain
size tends to become finer from the north to the
south. One is the formation of the desert. Some
researchers insisted that Taklimakan Desert originally
developed from the local underlying sediments (Li et
al., 1990). Therefore, the different source of sediments for the dunes determined the mean grain size
distribution from the north to the south. The other
factors are the stress and the direction of the winds
that move the sand that have resulted in this trend.
Generally, sands downwind the source zones are
finer than those near the source zones (Goudie et al.,
1987). Though the difference of mean grain size does
exist for different dune types in the northeast Taklimakan Desert (Fig. 7), specific associations between
dune types and sorting parameters are difficult to
establish. Neither do the grain size parameters in
the northeast show any regularity nor do the grain
Table 1
Comparative grain size and parameters for different dune types in northeast Taklimakan Desert. The parameters were calculated after Folk and
Ward (1957) and n is the sample number
Dune types
Mean grain size (phi units)
Standard deviation
Skewness
Complex crescent, n = 15
2.10 – 3.20
Average: 3.03
3.25 – 3.40
Average: 3.33
3.10 – 3.60
Average: 3.35
0.20 – 0.49
Average: 0.42
0.24 – 0.35
Average: 0.29
0.26 – 0.57
Average: 0.40
0.06 to 0.38
Average: 0.18
0.03 to 0.004
Average: 0.01
0.04 to 0.57
Average: 0.17
Dome, n = 4
Complex linear, n = 15
X. Wang et al. / Geomorphology 42 (2002) 183–195
191
Fig. 7. Bivariate plots of grain size parameters for the dune sands in northeast Taklimakan Desert. (a) Bivariate for mean grain size and standard
deviation. (b) Bivariate for mean grain size and skewness.
size components have any significant correlation
with the width of the interdune areas or the dune
heights.
4.2. Distribution of drift potential (DP) and the
amount of sand transport
Wind regime is another important factor that determines the development and morphology of sand
dunes (Bagnold, 1941; Pye and Tsoar, 1990; Lancaster, 1995). According to Fryberger’s (1979) classification, the VU values of DP (1992 – 1998, averaged)
in northeast Taklimakan suggest that it is an area of
low wind energy (Fig. 8). The mean annual DP is 54–
112. VU values are high in March to August and
nearly zero in the winter. In spring, the resultant drift
direction (RDD) is toward E. In summer, however,
RDD is mainly toward N in Xiaotang and Mancan but
NNE and ENE in the central desert (Tazhong). The
RDD changes distinctly from the border area of the
desert to the central part even during the same period
of the year. The RDP/DP ratio in the crescent dune
area is 0.54. In the areas of dome-shaped dunes and
compound linear dunes, the RDP/DP values are 0.54
and 0.58, respectively, with slight variations in different seasons. This result does not coincide with those
Fig. 8. Distribution of drift potential in Xiaotang, Mancan and Tazhong where compound/complex crescent, compound dome-shaped, and
compound/complex linear dunes are distributed. The results were calculated from the wind data records from 1992 to 1998.
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X. Wang et al. / Geomorphology 42 (2002) 183–195
of the other sand seas (McKee, 1979). In most of the
sand seas in the world, the ratios of the RDP/DP is
generally between 0.7 and 0.8 for compound/complex
crescent dunes (e.g. Wasson and Hyde, 1983; Lancaster, 1995). The wind regime in the area of complex
crescent dunes in the northeast Taklimakan Desert is
similar to that in the Algodones desert where complex
crescent dunes are developed (RDP/DP is 0.43)
(Havholm and Kocurek, 1988). Though the RDD
changes in spring and summer, the resultant vector
sum of sand transport is approximately perpendicular
to the advance directions of the complex crescent
dunes. For the complex linear dunes in the northeast
Taklimakan Desert, they are mainly developed in
acute bidirectional wind regimes. Four main directional sectors are important for deciding the trends of
the complex linear dunes: ENE, NNE, ESE and NNW.
They account for about 40%, 15%, 10% and 10% of
the sand transport, respectively. The high values of DP
in ENE direction coincide well with the morphologies
of the subdunes in NE side of the complex linear
dunes: the scale of the subdunes on NE side is larger
than those developed in NW side. And in some areas,
coalescence is developed between the complex linear
dunes. However, it is difficult to explain the morphologies of the dome-shaped dunes solely on the basis of
the wind regimes that occur in their distribution area.
The RDP/DP value in the dome dune area is 0.54, a
wind regime under which some other dune types such
as compound or complex linear dunes have also
developed. This result suggests that the morphology
of sand dunes in the northeast Taklimakan is related
not only to the wind regime but also to the sand
supply and to the other factors controlling the morphology of the dunes. The proliferation of dune forms
is the result of complex interactions between a number
of factors (Livingstone and Warran, 1996).
The distribution of DP is of great importance in
analyzing the change and the stress of the regional
wind regime. For measuring the dune mobility index
specifically, the importance lies in measuring and
calculating the real amount of sand transport (Lancaster and Helm, 2000). But there are prominent differences between the actual amount of the sand transport
and the values calculated with theoretical sand transport equations (Sarre, 1987). In the northeast Taklimakan Desert, Chinese geomorphologists have
obtained some regional equations for sand transport
Table 2
Sand transport equations for compound linear dunes in northeast
Taklimakan based on field observations
Of compound
linear dunes
Equations
Coefficient
of correlations
Crest
Middle of
the windward
Toe of windward
Interdunes
Q = 1.2 10 1 V 2.2246
Q = 1.1 10 1 V 2.1985
0.98
0.98
Q = 4.9 10 5 V 5.3805
Q = 3.1 10 5 V 5.3580
0.96
0.96
Where Q: kg m 1 h 1, V: Mean wind velocity, m s 1, recorded at
the standard heights (11.2 m) and the values are limited between 6.0
and 15.0 m s 1. The threshold wind velocity is 6.0 m s 1 in
northeast Taklimakan Desert. h is the duration of sand moving
winds (hours) (after Wang et al., 1997).
by regression analyses of the field data (Wang et al.,
1997, Table 2). Table 2 gives some examples of
equations in different parts of compound linear dunes
based on field observations.
According to the wind data and the sand transport
rate measured in the field together with the calculation
by the equation of sand transport on the crest of
compound linear dunes, the annual amount of sand
transport (1992 – 1998, averaged) on top of the compound linear dunes increases from 5500 kg m 1 near
the border to 8700 kg m 1 in the centre of the desert.
The maximum sand transport in the centre is about
11000 kg m 1. Distribution of sand transport shows
consistency with the types and scales of the sand
dunes. The sand transport in the area of crescent dunes
near the border of the desert is 63% of that in the area
of compound linear dunes in the central desert.
Furthermore, the sand transport in different directions
coincides with the distribution of drift potential. The
resultant sand transport also increases from 2300 kg
m 1 in the border area to 4200 and 6300 kg m 1 in
dome dune area and compound linear dunes area,
respectively. Similar to resultant drift potential, the
direction of annual resultant sand transport varies
slightly.
4.3. Sand supply, vegetation and landforms
The sands in northeast Taklimakan originate from
the local Quaternary alluvial plain deposits of the old
rivers and from some lacustrine sediments (Zhu et al.,
1981). They are not from the Lopo Nor area as earlier
studies suggested (Hedin, 1896) because (1) the
X. Wang et al. / Geomorphology 42 (2002) 183–195
compound/complex crescent dunes developed in
mainly old river beds which can be easily identified
from the aerial or satellite images and some separate
crescent dunes are still developing, and (2) data from
cores in the area of dome-shaped dunes reveal that the
upper 50 m of sediments are composed of the Quaternary alolian sediments and below 50 m are Quaternary
alluvial and lacustrine deposits. The mineral components of the dune sand do not show much difference
from those of the alluvial – lacustrine sediments underneath (Wu, 1981).
The amount of sand available for dune building
might be a second important control on dune types
(Wasson and Hyde, 1983). Crescent dunes develop
when the area has a low sand supply and linear dunes
appear in the area where sand supply is moderate (e.g.
Lancaster, 1995). Many researchers believe that the
Taklimakan Desert was originally formed in the centre
of Tarim Basin as early as in Tertiary (Dong, 1997;
Wu, 1981; Zhu et al., 1981) and then the desert
expanded outwards (Li et al., 1990). The thickness
of the Quaternary alluvial –lacustrine deposits in the
area of compound/complex crescent dunes is between
500 and 800 m, and the sand supply was generated
from the alluvial sediments of Tarim River. For the
area of dome dunes, the thickness of sediments is
between 400 and 800 m, and with a mean of about
700 m. The sand supply for the compound linear
dunes in the central basin is generally considered to be
from the alluvial materials carried by the rivers Andier
and Niya from Kumlun Mountain to the interior of the
desert (Wu, 1981; Qian and Wu, 1995), and the
thickness of sediments is between 300 and 800 m.
The huge amount of Quaternary sediments served as
the source material for the formation of the dunes in
the northeast Taklimakan Desert. However, the thickness of the sediments can only be regarded as some
unspecified measure of the sand available for dune
formation (Livingstone and Warran, 1996; Kocurek
and Lancaster, 1999). The sand available, the time
scale for dune formation and the sand-moving winds
may, to a large extent, be responsible for the scales
and the morphology of the dunes in the northeast
Taklimakan Desert. From the border of the desert
toward the centre of the desert, with the variations
in sand availability, dune formation history and the
strengthening of the sand-moving winds, the crescent,
dome and linear dunes have developed successively.
193
The vegetation cover in northeast Taklimakan is
very low except for some small areas of Popular
diversifolia forest in the old riverbeds of Tarim. Only
some Tamarix grows in the interdune areas or on sand
dunes sparsely and sporadically in most of the area.
The mean vegetation cover in this area is far below
14%, above which is generally considered to be able
to prevent sand transport by wind (Wiggs et al., 1995).
Therefore, the vegetation in this area has no significant influence on the formation of modern sand dunes.
Landform is a controversial factor. It is generally
thought that the morphology of dunes in the northeast
Taklimakan has no visible relationship between the
local original landforms. But some researchers hold
different views (e.g. Zao, 1991). For instance, the
relationship between the formation of the compound
or complex linear dunes in the middle of the desert
and the local landforms is still in debate. No conclusions have been drawn about the effects of the
uplifts in Minfeng area on the formation and distribution of the regional sand dunes (Zao, 1991). Since
there is no bedrock visible on the surface of the whole
area between the Tianshan and Kunlun Mountains,
more evidence is still needed.
5. Development and movement of the sand dunes
Controversies also exist over the patterns of formation or development of the several types of dune in
the Taklimakan Desert. Though the helical roll
hypothesis explaining the formation of linear dunes
proposed by Hanna (1969) and Wilson (1973) has
been rejected by most recent studies (e.g. Tseo, 1993),
some geomorphologists still believe that linear dunes
began to develop as the area was controlled by helicallike flows in the Taklimakan sand sea (e.g. Wu, 1981,
1987). But most Chinese geomorphologists stress that
the compound and complex linear dunes in the central
desert evolved from several types of simple dunes,
especially crescent dunes (e.g. Zhu et al., 1981; Wang
et al., 1997). The pattern of formation is similar to
those put forwarded by Bagnold (1941) and Lancaster (1989): separate crescent dunes ! crescent
chains ! compound crescent chains ! compound linear dunes. Repeated field observations of the simple
linear dunes in this area have also testified to this
pattern.
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X. Wang et al. / Geomorphology 42 (2002) 183–195
Fig. 9. The relationships between the dune height (m) and the
advance rates (m/year) for simple crescent dunes in the northeast
Taklimakan Desert.
Mobility is the most striking and alarming property
of dunes (Livingstone and Warran, 1996). Many
calculations have been made to determine the migration rates of dunes (Bagnold, 1941; Liu, 1960; Zhu et
al., 1981). Most observational data are from small
crescent dunes as it is not possible to make field
observations on large, compound linear dunes.
According to several years of field observations, the
advance rate of the crescent dunes near the border of
the desert is 1– 15 m/year (Fig. 9). Analysis of the
aerial photographs shows that the rates of advance of
the crescent dunes and compound linear dunes in the
central desert, however, are 3 – 20 m/year and less than
1 m/year, respectively (Wang et al., 1997).
bution, morphology and scales of the sand dunes.
There is an angle of 0 – 30° between the trend of the
dunes and the RDD. Calculations show that under a
low energy wind regime, the amount of sand transport
near the border is 5500 kg m 1 and in the central
desert 8700 kg m 1 with a maximum of 11,000 kg
m 1. The resultant sand transport in the central desert
is 2.74 times that near the border of the desert.
The sand supply for the dunes in the northeast
Taklimakan is not from Lopo Nor area in the east but
mainly from local alluvial or lacustrine deposits. The
morphology of the sand dunes is formed when these
alluvial – lacustrine materials are transported under the
particular wind regimes. The wind regimes, sand
available and the time scales for dune development
jointly account for the dune formation.
There have been no final conclusions for the period
when the dunes and their morphology developed as
the age of the desert have not been studied systematically. Furthermore, the morphodynamic processes
of the dunes have not been studied perfectly either.
For the future, emphasis should be placed on the
research on the morphodynamic processes, the development of the dunes in this area and the expansion
and contraction behaviour of the sand sea.
Acknowledgements
6. Conclusions
Three types of sand dune exist in the northeast
Taklimakan Desert, namely compound/complex crescent dunes and crescent chains, compound domeshaped dunes and compound/complex linear dunes.
Besides these three compound types, separate dunes
of several simple types are also distributed throughout
the sand sea.
Compared with the other sand seas of the world,
the Taklimakan has the finest sands and the grain size
tends to become finer from the north to the south.
Similar to the results of previous studies (Thomas,
1988; Lancaster, 1989), the grain size component does
not correlate to spacing or to the height of the dunes.
Analyses of the drift potential and drift direction
suggest evidently that northeast Taklimakan is an area
of low wind energy. Resultant drift potential and
resultant drift direction coincide well with the distri-
This work is supported by the Hundred Talents
Project of the Chinese Academy of Sciences and the
National Key Project for Basic Research on Western
Chinese Arid Areas (G1999043504). We are grateful
to one anonymous referee, and particularly to Prof.
Nicholas Lancaster for his review and invaluable
suggestions for improving the manuscript.
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