Wind Sand Research Articles

Control of Lunar and Martian Dust—Experimental Insights from Artificial and Natural Cyanobacterial and Algal Crusts in the Desert of Inner Mongolia, China

Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space.

The dependency of sand transport rate by wind on the atmospheric stability: A numerical simulation

A theoretical model of the process for wind–sand flow is developed through consideration of the coupling between wind flow and the motion of sand particles under different atmospheric stability conditions. Using this model, we studied the effects of atmospheric stability on the sand transport rate, the number of sand particles per unit area and time, and the duration before a steady state is achieved in detail. The results show that atmospheric stability has a strong effect on the movement of the wind–sand flow, and produces results with different characteristics from those previously reported in the literature which apply only to conditions of neutral stability. Under unstable conditions, the wind–sand flow reached equilibrium more quickly, with a higher total sand flux and sand flux at all heights than under neutral or stable conditions.

Probability of rebound and eject of sand particles in wind-blown sand movement

When incident particles impact into a sand bed in wind-blown sand movement, rebound of the incident particles and eject of the sand particles by the incident particles affect directly the development of wind sand flux. In order to obtain rebound and eject lift-off probability of the sand particles, we apply the particle-bed stochastic collision model presented in our pervious works to derive analytic solutions of velocities of the incident and impacted particles in the post-collision bed. In order to describe randomness inherent in the real particle-bed collision, we take the incident angle, the impact position and the direction of resultant action of sand particles in sand bed on the impacted sand particle as random variables, and calculate the rebound and eject velocities, angles and coefficients (ratio of rebound and eject velocity to incident velocity). Numerical results are found in accordance with current experimental results. The rebound and eject lift-off probabilities versus the incident and creeping velocities are predicted.

RETRACTION: Numerical simulation of a wind-sand flow under different conditions of atmospheric stability

A theoretical model for wind-sand flow is developed by considering the coupling between wind flow and sand particle motion, the latter subject to the Magnus effect, under different atmospheric stability conditions. Using this model, the characteristics of the wind-sand flow are discussed in detail. The results show that the atmospheric stability and the Magnus effect both have a strong influence on wind profiles and on the trajectories of sand particles. This approach produces results with characteristics that differ from those previously reported; the latter only applying to atmospheric conditions of neutral stability. The saltating sand reaches a greater height under non-neutral stability than under neutral stability, while the maximum horizontal distance is greater under unstable conditions and is smaller under stable conditions than under conditions of neutral stability.

A computer program (WDTSRP) designed for computation of sand drift potential (DP) and plotting sand roses

AbstractWind Data Tabulator and Sand Rose Plotter (WDTSRP) is an interactive developed computer program accessible for estimating sand transport potential by winds in barren sandy deserts. The Fryberger (1979) formula for determining sand drift potential (DP) was adopted to create and develop the computer program. WDTSRP is capable of working out weighting factors (WFs), frequency of wind speed occurrence (t), drift potential (DP), resultant drift potential (RDP) and directional variability of winds (DV) and of plotting sand roses. The developed computer program is built up of a simplified system driven by a group of options and dialogue boxes that allow users to input and handle data easily and systematically. Copyright © 2006 John Wiley & Sons, Ltd.

Regularities of wind-erosion of different land-use types in Yongding River sandy land, Beijing

The threshold wind velocity of a number of variables was studied in four different land-use types: farm land, forestland, wild grassland and a flood plain in the Yongding River sandy land in Beijing. The variables studied were transport of sand, underlying surface roughness, windblown sediment, wind-sand flow structure, soil mechanical composition and amount of wind erosion. The following conclusions were drawn: 1) The order of decreasing threshold of wind speed for sand displacement and surface roughness were forestland, wild grassland, farm land, sparse wild grassland and flood plain. 2) There were significant differences in sand flux among different ground covers. At a height of 0–20 cm, the height increased while the sediment discharge percent of sand flux decreased; there were significant differences in the sand flow formation under different land-use types. 3) The mechanical composition of sand particles consisted mainly of silver sand in the flood plain and sparse wild grassland, and of silver sand, particle silver sand and floury sand in other land-use types. 4) The amounts of wind erosion and sand sediment were different among different land-use types. Increased vegetation cover and change in farming techniques were suggested to prevent and control wind erosion of sand and soil.

Blown‐sand transport rate

AbstractSeveral sand transport rate data sets and eight representative transport rate formulae are transformed using the dimensionless parameters ϕ = gQ/ρU3* and r = U*t/U* and the results compared on the (ϕ, r) plane. The formulae generate three different geometric patterns – constant, monotonic decreasing and concave downward – and the corresponding data displayed one more pattern, a monotonic increasing one. Stimulated by this discrepancy, a new general formula for the sand transport rate with ϕ and r as its basis is introduced; each of the representative formulae is either a particular case of it or an approximation to it. The four parameters in the new formula are determined for description of the four possible patterns exhibited by the data; their variation is established and their physical interpretation is discussed in relation to measured data of the characteristic parameters of wind flow and sand. Copyright © 2004 John Wiley & Sons, Ltd.

Aeolian sand transport: a wind tunnel model

Wind sand transport is an important geological process on earth and some other planets. Formulating the wind sand transport model has been of continuing significance. Majority of the existing models relate sand transport rate to the wind shear velocity based on dynamic analysis. However, the wind shear velocity readapted to blown sand is difficult to determine from the measured wind profiles when sand movement occurs, especially at high wind velocity. Moreover, the effect of grain size on sand transport is open to argument. Detailed wind tunnel tests were carried out with respect to the threshold velocity, threshold shear velocity, and transport rate of differently sized, loose dry sand at different wind velocities to reformulate the transport model. The results suggest that the relationship between threshold shear velocity and grain size basically follow the Bagnold-type equation for the grain size d>0.1 mm. However, the threshold coefficient A in the equation is not constant as suggested by Bagnold, but decreases with the particle Reynolds number. The threshold velocity at the centerline height of the wind tunnel proved to be directly proportional to the square root of grain diameter. Attempts have been made to relate sand transport rate to both the wind velocity and shear velocity readapted to the blown sand movement. The reformulated transport model for loose dry sand follows the modified O'Brien–Rindlaub-type equation: Q= f 1( d)(1− R u) 2( ρ/ g) V 3, or the modified Bagnold-type equation: Q= f 2( d)(1− R t) 0.25( ρ/ g) U * 3. Where Q is the sand transport rate, the sand flux per unit time and per unit width, in kg m −1 s −1; ρ is the air density, 1.25 kg m −3; g is the acceleration due to gravity, 9.81 m s −2; R u= V t/ V; R t= U *t/ U *; V is the wind velocity at the centerline of the wind tunnel, in m s −1; V t is the threshold velocity measured at the same height as V, in m s −1; U * is the shear velocity with saltating flux, in m s −1; U *t is threshold shear velocity, in m s −1; f 1( d)=1/(475.24+93.62 d/ D); f 2( d)=1.41+4.98exp(−0.5(ln( d/1.55 D)/0.57) 2); d is the grain diameter, in mm; and D is the reference grain diameter, equals 0.25 mm. The Bagnold's equation that asserts for a given wind drag the rate of movement of a fine sand is less than that of a coarse sand is not supported by the reformulated models.

Facilitation of seedling establishment by an endemic shrub in tropical coastal sand dunes

Facilitation is predicted to occur on coastal sand dunes as these ecosystems have the harsh physical conditions common during primary succession. In a tropical dune system on the Gulf of Mexico the spatial patterns of plant distribution were analyzed and the hypothesis that facilitation is the responsible mechanism was tested by monitoring changes in the micro-environment and performing a seedling planting experiment under natural conditions. Densities of seedlings and adults of late colonizer grasses were two to six times greater beneath the early colonizer shrub, Chamaecrista chamaecristoides, than in the exposed areas. Temperatures on the sand surface, wind speed and sand accretion were significantly reduced by the shade of Chamaecrista. Only phosphate contents during the dry season were significantly higher in sand in the shade than in exposed sand. In the field experiment, successful establishment of seedlings of two late colonizer grasses (Trachypogon plumosus and Schizachyrium scoparium) was low but was concentrated exclusively beneath the shrubs. The introduced plants were reproductive one year after onset of the experiment and remained vigorous after three years. The observed spatial aggregation among the target species may be a result of improved conditions in the shade of the shrub, which facilitated the survival and establishment of late colonizers. On top of the environmental amelioration, protection from recurrent disturbances such as substrate mobility is an additional beneficial effect of the shrub.

The blown sand disaster to the Tarim Desert Highway in Xinjiang, China

The Tarim Desert Highway in Xinjiang, China, the longest one in the world, has a length of 562 km, about 80% of which runs across, from north to south, the Taklimakan Desert. Obviously, the main problem of the road maintenance is the blown sand disaster. The research results showed: (1) the physical environment along the desert highway is characterized by strong winds, fine and loose ground materials, different dunes and so on, which provides the dynamical condition and material source for the formation of blown sand disaster to the road and its shelter system. Meanwhile, the trend and cross-section of the road and the structure of the shelter system, as damage objects, play important roles in the formation process of blown sand disaster; (2) the blown sand disaster to the shelter system is original from the intrusion of the drift sands and mobile dunes outside the shelter system, and the wind erosion and sand deposit caused by the air stream changes on the ground in the shelter system. The main damage object in the Tarim Desert Highway is the shelter system presently. The damage forms include wind erosion, sand burying and dune covering; and (3) the damaged length of the blocking sand fences is 83.7%, 88.4%, 72.4%, 72.8% and 40.3% and the damaged area of the straw checkerboard belts is 73.1%, 58.2%, 44.5%, 35.4% and 36.6%, in turn, in 5 different landform units from north to south, and, the disasters to fences and the straw checkerboard belts are 79.5% and 57.6% in the compound dunes while they are 64.6% and 37.7% in the interdunes

Polyethylene greenhouse cover aged under simulated sub-Saharan climatic conditions

The sand wind effect on the durability of low-density polyethylene (LDPE) used as greenhouse cover, kept under sub-Saharan climatic conditions, has been investigated. Sand winds were simulated with an apparatus developed in our laboratory. Infrared, UV visible spectroscopies, contact angle, interferential microscopy, differential scanning calorimetry and permeability measurements were performed on untreated samples and on samples submitted to a sand wind. The data analysis shows that the surface roughness is modified, leading to drastic decreasing of the UV–visible light transmission. This phenomenon is due to the presence of small sand particles inlaid in the sample surface and due to surface erosion. Sand wind does not affect O 2 permeation but decreases the rate of water absorption. Finally, in the range of experimental duration investigated in this work, no chemical action due to sand wind is observed.

The calculation of sand discharge entering qinghai lake and formation of submerged barries

青海湖流域沙漠以环湖分布为特点,又以ENE为集中。这一状态使多方向的风沙流入湖,而实际上入湖沙量是以W、N、E三个方向的流沙为主。根据入湖风沙公式计算,入湖风沙量为887.08×10⁴t/a。并推算出河流泥沙入湖为35.77×10⁴t/a,空中降尘为30.36×10⁴t/a。入湖后的沙质物在湖流、波浪的作用下,由西向东运移,堆积成水下沙堤,逐渐增高加宽露出水面,分隔成子湖。同时在干燥的气候作用下,导致湖面收缩,生态环境恶化。;The distribution of sand dune in Qinghai Lake Basin is characterized by a surrounding lake specially concentration at EEN shore. Therefore, the wind sand can enter the lake from difference directions, in fact, max. quantity of sand comes fom east t west and north directions. According to the calculation by the formula, the wind drift sand discharge of eatering the lake is about 88.708×10⁵ t/a, the silt discharge of empting the lake by rivers about 3.577×10⁵ t/a, and the falling dust discharge from air about 3.036×10⁵ t/a, The sandy materials entering the lake were transported by the lake wave and currents from west to east, forming the subaqueous barriers. The sandy barriers gradually became higher and wider, and emerged from the water by which lagooas were insolated from the lake. At the same time9owing to strong evaporation9the lake began to shrink and its ecological envivonments to get deteriorated.

Sand Wind and War

Sand Wind and War

Wind action and sand movement near Holkham Bay, North Norfolk Coast, England

In Holkham Bay, North Norfolk Coast, England, a wide beach and coastal dunes have formed as a result of wave action and wind activity. This article describes the experiments and field observations that were carried out to explore the nature of wind activity that is presently affecting the morphology of the beach and dunes.

Role of Storms in Development of Ancient Marine Ridge and Swale System: ABSTRACT

Upper Jurassic (Oxfordian) sediments of Montana and Wyoming were deposited on a broad, shallow-marine shelf. Facies relations demonstrate that much of this shelf was characterized by a series of sand ridges separated by muddy swales. Ridges attain a thickness of about 12 m, an axial length of at least several kilometers, and a width measured perpendicular to crest less than 1 km. The crests of individual ridges are not parallel with one another or with the paleoshoreline. Analyses of directional features reveal multidirectional current vectors within individual ridges. The vertical sequence of internal sedimentary structures reveals that the ridges were constructed in distinct episodes, during which current flow was at least in the upper low-flow regime. Each episode is r presented in the rocks by a unique style, scale, and vector of cross stratification. Storms are considered to be the main process responsible for the buildup of ridges, individual storms being responsible for each of the sedimentation units of which the ridges are composed. As sand supply, storm intensity, and wind direction varied from storm to storm, so the style, scale, and vectors of the resultant cross stratification varied. Fair-weather processes were minor factors in the development of the ridge and swale system. End_of_Article - Last_Page 775------------

Types and Functions of “Yasiki-mori” (forest in farmyard) on the Musasino Upland, Western Suburb of Tokyo (2)

The “Yasiki-mori” (forest in farmyard, or mantles of trees for houses) develops on the Musasino upland, a western suburb of Tôkyô, where there prevails the north-west wind in winter, causing the inhabitants to believe that the mantle is for the wind. As to the dis-tribution of the wind mantle, Dr. Yazawa has written a paper for this Review (Vol. 12, 1936, Nos. 1 and 2). The present author, who has studied the types and functions of the mantle, selected two villages, one of “Einzelfdorf” and the other of the “Strassendorf” type. The number investigated totaled 677 farm houses, of which 70%, have thatched, 25% zinc, and 5% tile roofs. (1) Farmyards having tree-belts all round them formed 64.4% (see Table 2, p. 630). The belts, which are dense, mostly, stand on the north and west sides of the yards (see Table 1, p. 629) which coincide with the direction of the prevailing wind in winter. (2) The trees are evergreens (nearly 75, %) and shed leaved (25%). In the former, quercus trees predominate, followed by cedar and bamboo; in the latter we find mostly zelkova trees. As to the distribu-tion of the trees according to direction: most of the quercus lie southward, followed by W, N, and E. The cedar lies mostly W, and least S, and the zelkova mostly N and S and least W and E. (3) Styles and types : The author classified them into 6 styles, M, Mz, Mq, Z, Q, Qq, Of these Mq, and Qq are developed the most, with tall hedges of Quercus on the south side (see Pls. 14 and 15). There are two types, the one the mixed forest (M), consisting of evergreens and shed leaved trees, and the other of quercus only (Q); their ratio is 7:3. M, which is large in size, is always found in old settlements and the rich farms, whereas Q is small found in new set-tlements and the poorer farms. This fact shows that the type indi-cates some of the history, and the social and economic conditions of a settlement. (4) Functions: (a) Wind mantle as protection from the prevailing wind in winter and tyfoon in summer. (b) Adjustment of climate in winter and summer. (c) Protection against sand winds and fires. (d) Econnomically, for wood as material for building and making tools. (e) Decoration of farmyards and houses. In Japan, these house mantles are also developed in Toyama, Tottori, Sizuoka, and I wate prefectures showing various styles and types of which the author will write on another occasion.

Two Trans-Saharan Motor Routes

DIRECT communication between the Mediterranean coast and Central Africa, via the Sahara, is possible by two routes. The more easterly, exploited by the Societe Algerienne des Transports Tropicaux, starts from Algiers and passes through the Ahaggar mountains, its termini being Kano and Fort-Lamy, with an extension westward to Niamey. The western route, operated by the Compagnie Generale Transsaharienne, starts from Colomb Bechar, which is reached by railway from Oran or Algiers, and, roughly speaking, follows the meridian across the Tanezrouft to the Niger at Gao, whence it continues to Niamey. On both routes hotels and depots have been built at convenient intervals and regular transport services are operated, accommodation being provided for passengers. The S.A.T.T. runs a weekly service as far as Tamanrasset in the heart of the Ahaggar mountains, and a fortnightly service beyond. The Transsaharienne services run once a week. The desert is virtually closed between the end of May and beginning of October and no public services run right across. Because there is a regular transport service on each route, it must not be assumed that there are roads across the desert. There is merely a track which has been cleared of major obstacles and is marked, where possible, in an unmistakable fashion. Driving sand winds however may completely obscure the track between markers and, if these are far apart, it may be necessary to steer a compass course until the track once more becomes recognizable. As the track is not metalled or provided with any artificial surfacing, it quickly deteriorates and it is generally found more convenient to mark out a fresh track when the old one is worn out. Old tracks are generally shown as closed by the simple expedient of laying a row of stones across the entrance to them. On both routes the tracks now in use may be expected to provide the hardest surface available in any particular region, but new and better ways are constantly being discovered and for this reason the mileage by either route may, between certain points, vary considerably in difFerent years. Where the ground is hard gravel the heavy lorries, used for the regular transport services, have rolled the track into a series of corrugations, which provide extremely uncomfortable running for a private car. When large expanses of sand have to be crossed, the track may be a quarter of a mile wide or more, for each driver seeks to avoid the ruts made by others and makes his own way across the virgin sand to the right or left of the route. Where sandy wadis, or dried-up river beds, have to be crossed, the approaches have been eased off by working parties and causeways of stones or reeds provided. On the Ahaggar route the track resembles a road wherever it passes over hard ground or through the mountains, for the larger stones have been moved to each side, clearly defining a highway of constant width. Where the track has been badly marked however there may be two or three parallel tracks made by drivers in search of better surfaces. At night it is unwise to follow any except the main track, however badly surfaced this may be. Across large

Societies and Academies

PARIS Academy of Sciences, April 1 (C.R., 200, 1161-1256). PAUL LANGEVIN: A suggested experiment of M. Dufour. This experiment was suggested as one capable of differentiating between classical kinematics and that of limited relativity. A mathematical analysis shows that, in the form laid down by M. Dufour, the experiment would fail to detect any difference. A modification is suggested by the author, which is theoretically capable of detecting the difference, but in practice it cannot be carried out. ERNEST ESCLANGON: Experimental researches on the optical dissymmetry of space. JULES HAAG: The algebraic structure of the admittances of a filter as a function of the frequency. FLORIN VASILESCO: The continuity of the potential through masses and the demonstration of a lemma of Kellogg. GHER-MANESCO: Exceptional homogeneous combinations of integral functions. ANDRE FORTIER: The kinematics of flow round profiles with hyper-sustaining arrangements. ADRIEN FOCH and CHARLES CHARTIER: The flow of a fluid below a sphere. PIERRE LEJAY and TSANG HUNG-Cm: Observations of the intensity of gravity at the centre of China. Table of results from sixty-five stations, showing the reduced values of g and the corresponding anomalies. LUCIEN BULL: A liquid string galvanometer. A modification of the string galvanometer, using a thread of water of 0 -3 mm. diameter. CH. LAVANCHY: General method of calculation for electrical networks. PIERRE GIRARD and PAUL ABADIE: The detection of molecular interactions by the relaxation time of polar molecules. ANDRE CHARRIOU and MLLE. S. VALETTE: The influence of the cations on photographic emulsions. MLLE. CECILE STORA: The action of gases (hydrogen, nitrogen, oxygen) on photo-cells with colouring matters. MLLE. YVETTE CAUCHOIS: Study of the L spectrum of mercury. C. G. BEDREAG: The place of protons and neutrons in the natural systematics of the elements. B. KURTCHATOV, J. KuRTCHATOv and G. LATYCHEV: The disintegration of boron by slow neutrons. The vapour of methyl borate was acted upon by slow neutrons and the effects followed by the Wilson method. The photographs show that the disintegration was accompanied by the emission of two heavy particles and not three as found by Chadwick and Goldhaber. B. KOURTCHATOW, I. KOURTCHATOW, L. MYSSOWSKY and L. ROUSSINOW: An example of artificial radioactivity, produced by bombardment with neutrons, without capture of the neutron. GEORGES WOLF: Study of the binary system strontium nitrate - strontium hydroxide. E. RINCK: Solidification diagrams of the alloys formed by two alkali metals; the potassium-rubidium alloys. FRANgois PUCHE: The thermal decomposition of the chloride and chlorosalts of palladium. MAURICE CHAIX: The ultra-violet absorption spectra of derivatives of diphenylene sulphide and diphenylene-sulphone. HENRI GUERIN: The reduction of the arsenates of the alkaline earths by carbon. Tri-calcium and tristrontium arsenates. GUY GIRE: The formation of basic sulphate and the precipitation of nickel in solution by magnesium. PIERRE CAERE and DAVID LIBERMANN: The reaction of thionyl chloride and phenylglycollie acid. M. TIFFENEAU and P. WEILL: The hydrobenzoin dehydration of phenylethenylglycol. The formation of oc-phenyl-crotonic aldehyde. VICTOR HARLAY: Some silver compounds of thiosemicarbazide and of the thiosemi-carbazones. FRANCOIS SALMON-LAGAGNEUR: Some reactions of the chloride of the oc-mononitrile of camphoric acid. ISSAC KOGA and MITSUO SHOYAMA: The frequency-temperature characteristics of quartz plates oscillating with zero temperature coefficient. J. FRANC DE FERRIERE: The history of the loess soils of the Rhenish terraces in Haute-Alsace. Louis and HENRI LONGCHAMBON: The extension of the Toarcian hydrocarbon facies in the east of France. CH. COMBIER: The constitution of the sand winds in Syria. ROBERT GIBRAT and GEORGES VIEL: The relation between the electrical conductivities of the air and the danger arising from lightning. R. GUIZONNIER: The amplitude of the semidiurnal component of the gradient of terrestrial electric potential and solar activity. MME. C. SOSA-BOUR-DOUIL: Physiological researches on the parents and hybrids of the bean, Vicia Faba. MAURICE MARIE JANOT: The action of folliculine and equilenine on the development of the hyacinth. JOSEPH and CHARLES BOUGET: Cultures of tubers obtained by the germination of seeds of potato raised in the mountains in 1933. ROBERT ECHEVIN: The absorbing power of soils towards magnesium chloride. Louis MAUME and JACQUES DULAC: The C/N ratio in the wheat plant at heading and flowering: its marked variations with the medium. JAMES BASSET, EUGENE WOLLMAN, MICHEL A. MACHEBCEUF and MICHEL BARDACH: The biological effects of ultra-pressures: the action of high pressures upon tumours. MLLE. HENRIETTE GARRAULT: The formation of rods of elastoidine in embryos of Salmonidse. P. LECOMTE DU NOUY and MLLE. VIVIANE HAMON: A new method of estimating the diphtheria antitoxin by the viscosity. RENE LEGROUX and ANDRE LWOFF: The schizogonic evolution of the macro-gametocyte of Hcemoproteus paddce. FREDERIC DIENERT: Study of the clarification of water by micro-organisms. PAUL GIROUD and HARRY PLOTZ: Crossed immunity between cultures of historic exanthematic typhus (murin) and the virus of passage.