Characteristics of the wind regime north of Jubail, Saudi Arabia ...

Journal of Arid Environments (2001) 47: 387–402
doi:10.1006/jare.2000.0668, available online at http://www.idealibrary.com on
Characteristics of the wind regime north of Jubail,
Saudi Arabia, based on high resolution wind data
Hans-JoK rg Barth
University of Regensburg, Department of Physical Geography,
UniversitaK tsstr. 31, D-93051 Regensburg, Germany
(Received 6 April 1999, accepted 13 June 2000, published electronically 26 January 2001)
An analysis of regional wind data was based on the measurements of two
weather stations for a period of 2 years. Ten-minute mean values where based
on readings in 10-s intervals. In the study, wind direction and sand drift
potential were considered. During the course of 1 year six different wind
regimes occured: (1) a high energy Mediterranean north-west regime from
November to February; (2) a bimodal cyclonic end-phase in March; (3) a
moderate eastern spring phase in April; (4) a complex transition phase in May;
(5) a high energy summer Shamal regime from June to August; and (6) a low
energy autumn phase in September and October. Concerning sand movement
potential, two of the phases are not relevant, two show bimodal or complex
patterns, and two significantly dominate sand movement from north to south.
The summer high energy regime coincides with the unfavourable season for
plant growth and thus the lowest vegetation cover. Regarding the actual sand
drift the Eastern Province of Saudi Arabia is influenced by a unimodal wind
regime causing a sand flow from the north areas to the south. There is an overall
decrease in wind energy and sand transport rates, so that accumulation
dominates in the southern Jafurah and northern Rub’al Khali. Vegetation
characteristics and geomorphological features indicate the amount of actual
sand dynamics in the study area. According to such observations and conventional
meteorological data, the Eastern Province can be divided into three
regions: (1) a sand source region in the north which increases due to a continuing
reduction of the vegetation cover; (2) a transport zone where sand input
from the north equals sand output to the south, and (3) the accumulation zone
in the south which shows a positive sand budget.
� 2001 Academic Press
Keywords: Eastern Province; wind regimes; wind action; wind erosion
Introduction
Wind is the most effective transportation agent in sand deserts, because usually dry
surfaces and only sparse vegetation exist in this environment. Where moisture and plant
cover diminish, timing and location of aeolian activity is determined by sediment supply,
surface characteristics and wind velocity. The Eastern Province of Saudi Arabia used to
be covered by enough vegetation to prevent active sand movement. During the last few
decades the situation has changed dramatically. Industrialization and urbanization
around the centres of Dhahran and Jubail have led to an increase of recreational activities
in the surrounding deserts. However, the major cause of the destruction of vegetation is
0140-1963/01/030387#16 $35.00/0 � 2001 Academic Press

388 H.-J. BARTH
grazing because it effects even remote areas due to water trucking. Sand movement
now occurs throughout the whole area. Controls on sand transport as well as estimates
on potential sand movement rely on wind data. The purpose of this paper is to analyse
detailed wind measurements, to characterize the wind action system of the Eastern
Province throughout the course of a year, and to show that daily mean values of wind
speed measurements may not at all be useful to estimate the potential of sand movement
in certain regions.
Quantification of sand movement using methods other than field measurements often
presents problems. Interactions of different variables such as grain size distribution,
wind velocity, vegetation density, vegetative characteristics, wind exposure and moisture
of the top soil layer determine the amount of sand which is transported. Numerous
authors worked on these problems (Marshall, 1971; Thomas, 1975; Lettau & Lettau,
1978; Wasson & Nanninga, 1986; Buckley, 1987; Sarre, 1988; Hesp et al., 1989;
Stockton & Gillette, 1990; Cooke et al., 1993; Lancaster, 1998). One conclusion to arise
was that wind measurements as the only source of data are certainly not sufficient to
estimate sand transport rates. Regarding the potential aeolian sand carrying capacity on
plant-free dry surfaces we know from Bagnold’s classic paper, The physics of blown sand
and desert dunes (1941), that with increasing wind speed there is an exponential increase
in potential sand movement (Fig. 1).
Figure 1. With increasing wind speed there is an exponential increase in potential sand movement
(Bagnold, 1941).

CHARACTERISTICS OF A WIND REGIME 389
Table 1. Monthly mean values of wind speed (m s !1 )
Month Abu Kharuf Abu Ali
Sep 3)9 4
Oct 3)8 4
Nov 5)2 6)9
Dec 4)7 7)3
Jan 4)8 6)4
Feb 4)9 6)5
Mar 4)8 5)1
Apr 4)9 4)6
May 4)9 5
Jun 5)4 5)4
Jul 6)4 5)4
Aug 4)9 4)6
Mean 4)9 5)4
The curve shows the rate of sand movement of an average dune sand
(mean"0)25 mm) in tons m !1 h !1 for wind speeds measured 1 m above ground level.
The problem of using conventional meterological data for estimating potential sand
carrying capacity in a practical way is the low resolution of wind measurements. Usually
mean values are registered (daily or hourly), but monthly mean values of wind speed are
totally useless for any estimates of sand movement. Example, at the Abu Kharuf station
there is an average wind speed of 3)8ms !1 (10 m above ground level) in October
(Table 1). This suggests there was no sand movement at all, because this value is below
the threshold velocity (at which sand movement is initiated) of about 6 m s !1 . But in
fact there were 19 days where wind speeds significantly exceeded the threshold velocity
(see Fig. 2).
Figure 2. Autumn situation with regular diurnal pattern and low energy.

390 H.-J. BARTH
Analysis of high resolution wind data provided by two weather stations
north of Jubail
The two automatic climatological recording stations (Thies CLIMA, GoK ttingen,
Germany) are located at the eastern tip of Abu Ali Island representing a marine climate
(27318�03�N and 49341�57�E) and at Jebel Abu Kharuf (27322�26�N and 49310�21�E),
an inland area 5 km from the coast line. Because the main wind direction is north to
north-west the air masses already pass over 50 to 60 km of terrestrial area before they
reach the station on Abu Kharuf, and therefore represent a coastal terrestrial climate
(Fig. 3). In the following explanations only the data recorded at Abu Kharuf is
considered.
Data was recorded from September 1993 until November 1995. Wind speed and
direction was recorded every 10 s. The data logger (Thies DL15) was powered by
a 12 V battery. For data transmission a memory card (256 K) was used. The fact that
data could only be collected every 3 weeks (due to remote locations and lack of
personnel) and limitations of the memory card’s storage capacity meant it was not
possible to record the 10-s values. Every 10 min a mean value was calculated automatically
based on the measurements that were made every 10 s. Even the 10-min mean
values did not represent data for exact estimations concerning the potential sand
carrying capacity because highly effective high-speed gusts are smoothed into lower
speed mean values. But this was still sufficient to show the large-scale characteristics
of the Eastern Arabian coastal wind regime.
Figures 3}5 show that the wind velocities mostly display a diurnal pattern with calm
winds at night and maximum values during midday or afternoon. This is a typical
characteristic of desert winds. At night cooling creates a stable surface layer. The
temperature inversion prevents vertical air exchange. As the sun rises convection
disturbs the inversion, probably supported by gravity waves at the surface of the
inversion (Warren & Knott, 1983). The unstable atmosphere promotes turbulent
vertical air exchange bringing high velocity upper winds down to the surface. Wind
speeds usually continue to increase until the afternoon, driven largely by convection.
Figure 3 represents a typical autumn situation with a very regular diurnal pattern
beginning with almost complete calm in the early morning and culminating in the
afternoon to wind speeds between 5 and 9 m s !1 . Figure 4 represents a winter regime.
Mediterranean depression generally provide a higher wind speed, higher variability and
days when wind velocity never drops below 6 m s !1 . Figure 5 represents the Shamal
Figure 3. Location of weather stations.

CHARACTERISTICS OF A WIND REGIME 391
Figure 4. Winter regime with higher variability and energy.
time in early summer with strong and hot northerly winds exceeding 15 m s !1 during
midday, abating at dawn and sometimes coming to a complete rest.
On the basis of the 10-min mean values, four wind classes in the efficient velocity
range were created. Low winds not able to transport sand (potentially) were not
considered. Class 1 covers the range between 6}9 ms !1 (mean"7)5ms !1 ), class
2 covers 9}12 m s !1 (mean"10)5 ms !1 ), class 3 covers 12}15 m s !1 (mean"
13)5ms !1 ) and class 4 covers 15}18 m s !1 (mean"16)5ms !1 ). For each month the
Figure 5. Summer regime with regular diurnal pattern and high energy.

392 H.-J. BARTH
Month
Table 2. Potential sand movement at Abu Kharuf in 1993/94
Wind speed
class (m sec !1 )
Hours
blowing
Potential sand
movement
(t m !1 )
Total
potential sand
movement (t m !1 )
November 7)5 149 0)23
10)5 52)8 1)23
13)5 9)2 0)92
16)5 0)8 0)21 2'59
December 7)5 106)8 0)16
10)5 8)5 0)21 0'37
January 7)5 179)7 0)28
10)5 27)2 0)66
13)5 4)8 0)48 1'42
February 7)5 148)7 0)23
10)5 27)4 0)67
13)5 3)8 0)38
16)5 0)5 0)13 1'41
March 7)5 73)6 0)11
10)5 41)8 1)02
13)5 9)6 0)96
16)5 0)5 0)13 2)22
April 7)5 135)9 0)21
10)5 38)4 0)94
13)5 3)4 0)34
16)5 0)2 0)05 1'54
May 7)5 125)5 0)19
10)5 39)2 0)96
13)5 12 1)21
16)5 2)2 0)53 2'89
June 7)5 104)1 0)16
10)5 55)7 1)36
13)5 12)3 1)26 2'78
July 7)5 151)7 0)23
10)5 46)8 1)14
13)5 4)3 0)43
16)5 0)2 0)05 1'85
August 7)5 130)6 0)2
10)5 53)1 1)3
13)5 4)8 0)48 1'98
September 7)5 24)3 0)04 0'04
October 7)5 96 0)15
10)5 1)4 0)03 0'18
time period that a certain velocity range persisted was summed (Table 2). On the basis
of the sand transport equation after Bagnold (1941) the potential sand movement
capacity of each wind class was calculated in tons m��.

CHARACTERISTICS OF A WIND REGIME 393
The data show that a high proportion of sand can be moved by strong winds with low
frequency (Fig. 6), i.e. 49)5% of sand can be moved by winds blowing only during 4)5%
of the year. Winds blowing during only 0)73% of the year can move 33)6% of the sand,
and winds blowing only 0)05% of the year or 4)4 h can move 5)7% of the total sand.
So far wind direction has not been considered. According to the classification of
sand-moving wind systems by Fryberger & Dean (1979), there is a wide unimodal wind
regime with intermediate energy in the Jubail area. By analysis of wind speed and
direction over a 2-year period, 1 year can be divided into six different wind phases.
In the following section each phase is shortly described and illustrated by wind roses and
magnitude-frequency relationships after Lancaster (1985).
High energy Mediterranean north-west regime
In November, December, January, and February Mediterranean depressions usually
reach the northern Arabian Peninsula and cause north-westerly winds accompanied by
some precipitation, depending on how fast the winds passed over the Mediterranean
Sea. South-easterly winds probably result in currents on the south-eastern flank of the
continental Asian high pressure cell (Fig. 7).
Bimodal cyclonic end phase
In March the appearance of Mediterranean depressions significantly decreases due to
their poleward retreat. Easterly winds usually result in regional thermal action caused by
land}sea pressure differences and mark the end of the cyclonic activity (Fig. 8).
Moderate eastern spring phase
In April the inter regional pressure differences are low. The continental Asian low is
poorly developed and differs little from the tropical low. The North African high is
also not yet established. Easterly winds result in thermal action caused by land}sea
pressure differences (Fig. 9).
Figure 6. Magnitude frequency relationship between sand movement and windspeed
(1993/94).

394 H.-J. BARTH
Figure 7. Magnitude frequency relationship and wind rose diagrams for November, December,
January and February.
Complex transition phase
May marks a transition between the low and mostly thermal wind action in spring and
the Shamal typical for the summer months. Wind directions are complex during this
phase but velocities are generally high (Fig. 10).

CHARACTERISTICS OF A WIND REGIME 395
Figure 8. Magnitude frequency relationship and wind rose diagrams for March.
Figure 9. Magnitude frequency relationship and wind rose diagrams for April.
Figure 10. Magnitude frequency relationship and wind rose diagrams for May.

396 H.-J. BARTH
High energy summer Shamal regime
During June, July and August there are unimodal strong north to north-easterly winds
supported by two pressure zones. First, the continental Asian low pressure cell is fully
established and reaches from the Indian subcontinent into the Arabian Gulf. It provides
a northerly current on its western flank. Second, the eastern North African high pressure
cell supports northerly winds in the area of the Arabian Peninsula because of its
clockwise direction. Compared to the rest of the year stronger winds between
9}12 m s !1 are especially significant (Fig. 11).
Figure 11. Magnitude frequency relationship and wind rose diagrams for June, July and August.

CHARACTERISTICS OF A WIND REGIME 397
Low energy autumn phase
In September and October the Asian low pressure cell decreases considerably. At the
same time the North African high retreats back over the Libyan desert whereby the
pressure gradients decline and therefore variable low energy winds are characteristic for
the Eastern Province. Due to the high temperatures of the Gulf there are no significant
thermal winds during this time of the year (Fig. 12).
These observations lead to the following results concerning potential wind action in
the central coastal lowlands of the Eastern Province in Saudi Arabia:
(1) The total sand drift capacity applying Bagnold’s calculation and high resolution
wind data described above is about 19)3 tons m !1 y !1 . Calculations on the basis
of daily mean values lead to a much lower result of 2)1 tons m !1 y !1 . Thus,
concerning sand drift potential one formula may lead to considerably higher
results when higher resolution wind data is used.
(2) Concerning wind erosion, the most effective times of the year are the high
energy Mediterranean north-west regime from December until February and the
Figure 12. Magnitude frequency relationship and wind rose diagrams for September and October.

398 H.-J. BARTH
high energy summer Shamal regime from June until August. The latter period
coincides with the unfavourable season for plant growth and thus the lowest
vegetation cover. This makes the summer season the most important time in the
degradation process, which is intensified when animals are kept on the ranges
during this time.
(3) The effective sand drift direction is SSE. There is a potential loss of sand in
this direction which makes the region a potential sand source.
Current situation in the area
Major grazing activity during the last few decades and a continuously increasing animal
population accompanied by supplemental feeding and trucking of water have changed
the vegetation significantly (Barth, 1998b, 1999). Former extensive shrubland communities
such as Rhanterium epapposi (Mandaville, 1990) covering 15}20% of the ground
have become degraded Panicum grasslands which seldom exceed a ground cover of
more than 5% (Barth, 1998b). The ratio of biomass production between perennials and
annuals is 1: 4 in the heavily grazed areas compared to 2:1 in fenced areas with minor
grazing activity (detailed descriptions of signs and the state of degradation is given in
Barth, 1998a, 1999). This indicates that the rangeland ecosystems are disturbed to
a high degree. The reduction in vegetation cover reduced the most effective
protection against aeolian erosion, a process which has become common in this area.
Active sand dynamics are indicated by sand ripples, lag deposits and exposed root
systems, which are common in most vegetation types. The reactivation of previously
stabilized dunes can be observed on severely damaged spots. Hence, grazing pressure is
much higher than the ecological capacity of the rangelands. Another important fact is
that animals are continuously kept on the range. This practice intensifies degradation,
especially during the summer months when plant production is at a minimum and the
wind energy for aeolian erosion is at its maximum. This combination accelerates
the whole process of degradation and is the major cause of the region’s change into an
active sand source region with a negative sediment balance.
Model of wind action in the Eastern Province
In the Eastern Province of Saudi Arabia the northern areas are linked to the northern
Rub’al Khali in the south by the constant flow of a regional wind action system (WAS).
This provides continuous sand transport along the main wind direction (Fig. 13). The
three distinct regions of wind action were briefly described by Oguz et al. (1998). In the
northern coastal lowlands and the gravel plains of Wadi Al Batin high wind speeds occur
throughout the year (resultant drift direction is shown on Fig. 13), but no active aeolian
erosion can be observed. This is because in the gravel plains no erodible material is left
and in the coastal lowlands a dense vegetation cover prevents erosion of the sand sheets.
It is therefore a region with a potential negative sand budget (A1 in Fig. 14). In the South
of this region is the study area dominated by landforms typical for active wind erosion,
such as parabolic dunes, longitudinal dune stripes, sand sheets, nabkhas, giant ripples,
exposed roots on perennial vegetation, and sabkhas (Barth, 1998a, 1999). Here there is
definitely a negative sand budget (A2). In this area the vegetation cover was reduced to
a degree which allows wind erosion and sand movement in a southerly direction
according to the main direction in the unimodal wind regime. Further south (around the
area of Dhahran) barchanoid dunes and young sand sheets (Fryberger et al., 1984) are
typical of a transport zone and relatively balanced sand budget. Here (B in Fig. 14) sand
erosion and movement to the south equals sand input from the north. Decreasing wind
speeds to the south cause sand accumulation which is represented mainly by transverse

CHARACTERISTICS OF A WIND REGIME 399
Figure 13. Sand transport direction in the Eastern Province of Saudi Arabia.
chains (Mainguet & Dumay, 1998). In this area in the southern Jafurah and northern
Rub’al Khali the sediment balance is positive (C in Fig. 14). Studies by Anton (1983) in
the Eastern Province show that the dunes of the Jafurah desert (south of Dhahran) do
not seem to be more than 4000 years old and the result of a major change in the sand
dynamics of the northern regions. This could have been triggered by large scale
aridification which started around 5500 B.P. (Sirocko, 1996), followed by degradation
of the northern areas. Anton (1983) also believes that there is a change in grain size in
the dune sands from larger grains in the north to smaller grains in the south. This could
be typical for long distance sand movement (Mainguet & Chemin, 1991). In Fig. 14 the
generalized borders between the different sand budget zones were determined by
satellite image analysis and field observations. They should, therefore, be considered as
transition zones rather than precise sand budget divides.
Conclusion
During the course of one year six different wind regimes occur. These are:
(1) a high energy Mediterranean north-west regime from November to February;
(2) a bimodal cyclonic end phase in March;

400 H.-J. BARTH
Figure 14. Transport zones and sand budgets in the Eastern Province of Saudi Arabia. Dune
type location sources: field observation, satellite images, Breed et al. (1979).
(3) a moderate eastern spring phase in April;
(4) a complex transition phase in May;
(5) a high energy summer Shamal regime from June to August; and
(6) a low energy autumn phase in September and October.
Two phases (high energy summer regime and high energy Mediterranean north-west
regime) significantly dominate sand movement from north to south. The summer high
energy regime coincides with the unfavourable season for plant growth and thus the
lowest vegetation cover.
Predictions of sand transport rates are subject to numerous uncertainties and remain
qualitative estimates, but there is no question that low-frequency, high-magnitude wind
events are effective in transporting sand in the eastern Arabian Peninsula. To
estimate the potential sand movement when conventional meteorological data is used it
is necessary to register the unsteadiness (gustiness) of the wind. The more generalized
data is used for transport estimations, the less accurate are the achieved results.
In the Eastern Province of Saudi Arabia increasing human activity and overgrazing
have reduced the vegetation cover within the area of potential negative sand
balance (A1). Sand sheets and stabilized dunes, stripped of the protecting cover,
become active and are now exposed to wind erosion (A2). Areas of potential negative
sand balance are currently becoming areas of actual negative sand budget caused by land
degradation and wind erosion. By this process the transition zone between A2 and A1
moves northwards. This dynamic with a potential negative balance becoming an actual
negative balance is the most significant feature of ongoing land degradation in this
region.

CHARACTERISTICS OF A WIND REGIME 401
I am grateful to NCWCD, Riyadh for making this study possible. Many thanks to our project
manager Dr F. Krupp. Assistance, continuous help and co-operation both in the field and the
laboratory was provided by numerous individuals.
References
Anton, D. (1983) Modern eolian deposits of the Eastern Province of Saudi Arabia. In: Brookfield,
M.E. & Ahlbrandt, T.S. (Eds), Eolian Sediments and Processes. Developments in Sedimentology,
38: 365}378.
Bagnold, R.A. (1941). The Physics of Blown Sand and Desert Dunes. London: Chapman and Hall.
Barth, H.-J. (1999). Desertification in the Eastern Province of Saudi Arabia. Journal of Arid
Environments, 43: 399}410.
Barth, H.-J. (1998a). Sebkhas als Ausdruck von Landschaftsdegradation in den zentralen KuK stentieflaK
ndern der Ostprovinz Saudi Arabiens. Dissertation an der Ruhr-UniversitaK t-Bochum,
Regensburger Geographische Schriften, Bd. 29, Regensburg.
Barth, H.-J. (1998b) Status of vegetation and an assessment of the impact of overgrazing in an area
north of Jubail, Saudi Arabia. In: Omar, S.A.S., Misak, R., Al-Ajmi, D. & Al-Awadhi, N. (Eds),
Sustainable Development in Arid Zones, Vol. 2, pp. 435}450, Rotterdam.
Breed, C.S., Fryberger, S.G., Andrews, S., McCauley, C., Lennartz, F., Gebel, D. & Horstman,
K. (1979). Regional studies of sand seas, using Landsat (ERST) imagery. In: McKee, E.D.
(Ed.), A study of global sand seas. USGS Professional Paper, 1052: 305}381.
Buckley, R.C. (1987). The effect of sparse vegetation on the transport of Dune sand by
Wind. Nature, 325: 426}428.
Cooke, R., Warren, A. & Goudie, A. (1993). Desert Geomorphology. London: UCL.
Fryberger, S.G. & Dean, G. (1979). Dune forms and wind regime. In: McKee, E.D. (Ed.),
A study of global sand seas. USGS Professional Paper, 1052: 137}170.
Fryberger, S.G., Al-Sari, A.M., Clisham, T.J., Rizvi, S.A.R. & Al-Hinai, K.G. (1984). Wind
sedimentation in the Jafurah sand sea, Saudi Arabia. Sedimentology, 31: 413}431.
Hesp, P.A., Hyde, R., Hesp, V. & Zhengyu, Q. (1989). Longitudinal dunes can move sideways.
Earth Surface Processes and Landforms, 14: 447}452.
Lancaster, N. (1985). Winds and sand movements in the Namib Sand Sea. Earth Surface Processes
and Landforms, 10: 607}619.
Lancaster, N. (1998). Understanding the dynamics of aeolian sand transport systems - an
overview of recent progress. In: Omar, S.A.S., Misak, R., Al-Ajmi, D. & Al-Awadhi, N. (Eds),
Sustainable Development in Arid Zones, Vol 1, pp. 111}126, Rotterdam.
Lettau, K. & Lettau, H.H. (1978). Experimental and micro-meteorological field studies on dune
migration. Lettau, H.H & Lettau, K. (Eds), Exploring the World’s Driest Climate. pp. 110}147.
University of Wisconsin, Madison, Institute for Environmental Studies.
Mainguet, M. & Chemin, M.C. (1991). Wind degradation on the sandy soils of the Sahel of Mali
and Niger and its parts in Desertification. Acta Mechanica, Suppl. 2: 113}130.
Mainguet, M. & Dumay, F. (1998). The concepts of global wind action system and sediment balance,
keys for aeolian action and aesertification monitoring. Omar, S.A.S., Misak, R., Al-Ajmi, D.
& Al-Awadhi, N. (Eds), Sustainable Development in Arid Zones, Vol.1,pp.127}141, Rotterdam.
Mandaville, J.P. (1990). Flora of Eastern Saudi Arabia. London. 482 pp.
Marshall, J.K. (1971). Drag measurements in roughness arrays of varying densities and distribution.
Agricultural Meteorology, 8: 269}292.
Oguz, I., Khattab, G. Al-Hinai, Wasim, A. & Ali, A.Z. (1998). Desert geomorphology. Eolian
sand drift rates, and their role in design of sand control measures in the Abqaiq area. Saudi
Arabia. Omar, S.A.S., Misak, R., Al-Ajmi, D. & Al-Awadhi, N. (Eds), Sustainable Development
in Arid Zones, Vol. 1, pp. 213}221, Rotterdam.
Sarre, R.D. (1988). The morphological significance of vegetation and relief on coastal foredune
processes. Zeitschrift fuK r Geomorphologie. Supplementband, 73: 17}31.
Sirocko, F. (1996). The evolution of the Monsoon Climate over the Arabian Sea during the last
24 000 Years. K. Heine (Ed.), Palaeoecology of Africa, 24: 53}70.
Stockton, P.H. & Gillette, D.A. (1990). Field measurements of the sheltering effect of
vegetation on erodible land surfaces. Land Degradation and Rehabilitation, 2: 77}86.
Thomas, Y.-F. (1975). Actions eHoliennes en milieu littoral } la Pointe de la Courbe, MeH moires de la
Laboratoire de GeH omorphologie de l’ED cole des Hautes ED tudes 29.

402 H.-J. BARTH
Warren, A. & Knott, P. (1983). Desert dunes: a short review of needs in desert dune research and
a recent study of micrometeorological dune-initiation mechanisms. Brookfield, M.E. &
Ahlbrandt, T. S. (Eds), Eolian sediments and processes. Amsterdam: Elsevier.
Wasson, R.J. & Nanninga, P.M. (1986). Estimating wind transport of sand on vegetated surfaces.
Earth Surface Processes and Landforms, 11: 505}514.