Sandy Desert Areas Research Articles

An Innovative Concept for 3D Sand-Printed Sustainable Refugee Shelters in a Sandy Desert in a Hot and Dry Climate

This article deals with the urban and architectural concept of a shelter for refugees (refugees from civil war-stricken Syria), located in a desert area, in a hot and dry climate. The aim of the research was to develop a design concept for a temporary shelter that would provide refugees with decent living conditions and, at the same time, meet the demands of sustainable development. The conceptual design of the shelter includes a complex of 100 residential units intended for 500 refugees, service buildings, and public spaces. The proposed urban layout can be expanded multiple times. At an architectural scale, the concept includes several variants of residential units. To implement this project, it is proposed to use an innovative, environmentally friendly 3D printing technology employing quartz sand and using solar energy. The implementation of this technology in the construction of shelters for refugees in sandy desert areas will solve many problems related to logistics, availability of building materials, and energy costs. The design solutions proposed in the article are the result of taking into account technological, functional, cultural, humanitarian, economic, climatic, and ecological aspects.

Wind Tunnel Experiments and Field Observations of Aeolian Sand Encroachment around Vernacular Settlements in the Saharan and Arabian Deserts

One of the key repercussions of the desertification process in the Sahara and the Arabian desert is increased aeolian sand drift and sand deposition. Despite its isolated location and severe desert climate—particularly in terms of solar radiation, sand drift, and sand deposition—the region of El-Oued Souf in the Grand Erg Oriental in the Algerian Sahara has been a key cultural and trade center for many centuries. To resist the extreme weather conditions, the architecture of the vernacular settlements in the region of El-Oued Souf has unique design traits. Newly constructed buildings, on the other hand, frequently employ technologies based on models imported or imposed from climates that bear little resemblance to the desert. As a result, the inhabitants of these structures live more ‘in the desert’ than ‘with the desert’. This study investigates the impact and the effectiveness of vernacular desert architecture to resist aeolian sand encroachment problems in sandy desert areas. The sand accumulation patterns around vernacular buildings were identified and quantified using wind tunnel experiments. The size and shape of the buildings, as well as their geometric configuration within the settlement, were investigated in relation to the shape and dimension of sand accumulation formations. Field observations in north Algeria and the United Arab Emirates confirmed the accumulation patterns produced by the wind tunnel experiments. The study proposes possible design indicators for building forms to minimize the impact of sand deposition on such forms.

Effect of sand burial on the subcritical water repellency of a dominant moss crust in a revegetated area of the Tengger Desert, Northern China

Abstract Sand burial is a ubiquitous disturbance that influences the ecological and hydrological properties of moss crusts in many sandy desert areas. There is little available information regarding the effect of sand burial on the water repellency (WR) of moss crusts in desert areas. Therefore, this study evaluated the effects of sand burial (sand depths of 0 (control), 0.5, 1, 2, 4 and 10 mm) followed by three simulated precipitation regimes (through applying 4 and 6 mm, 2 and 3 mm, and 1 and 1.5 mm of distilled water at 8-day intervals in spring and autumn, respectively) on the WR of a widespread moss crust dominated by Bryum argenteum Hedw. in a revegetated area of the Tengger Desert, China. The results showed moss crust WR remained subcritical during the whole experiment, and that it considerably decreased immediately after sand burial, even though the values of WR were significantly higher in autumn than those in spring under the same treatment (p < 0.05). Furthermore, the depth threshold (TD) values for sand burials that reduced WR to zero were 1 and 2 mm in spring and autumn, respectively. After a recovery period of nearly one-season (72 days), the WR of the moss crust significantly increased (p < 0.05). In addition, sand burial had two separate effects on moss crust WR. Specifically, shallower sand burial (burial depth less than 0.5 mm) increased moss crust WR, whereas deeper sand burial (burial depth exceeds 0.5 mm) decreased it. The TD values also significantly increased to 2 and 4 mm in spring and autumn, respectively. These findings about the effects of sand burial on moss crust WR provide additional information that can be used to better understand the influence of sand burial on moss crust colonization and maintenance in arid sand-burial-stressed ecosystems, and to help explain why there are some contrasting viewpoints on biocrust WR.

Hydrological Cycle and Lake Water Source Indicated by Microrelief-Evaporite-Vegetation-Runoff Assemblage of Badain Jaran Desert

The hydrologic process of the sandy desert remains a focus in research in arid areas. Three major natural phenomena that can indicate the hydrological cycle in the extremely dry Badain Jaran Desert were found, namely the assemblage of megadune microrelief and evaporite, megadune vegetation and microrelief, as well as lakeside runoff and vegetation. The microrelief sand layer water, evaporite minerals, and lakeside hydrogeological features were analyzed by the drying and weighing method, environmental scanning electron microscopy with energy spectrum analysis functions, and a hydrogeological borehole survey. The water content of the microrelief 0–0.5 m sand layer is between 4.7% and 9.3%. The evaporite minerals are mainly composed of calcite (CaCO3) and gypsum (CaSO4). The shallow groundwater system in the off-shore area of lakes consists of an aeolian sand layer, a peat layer, and a lacustrine sedimentary layer, and the phreatic water with a thickness of 20 cm to 40 cm is reserved in the bottom of aeolian sand layer with a peat layer as a waterproof baseboard. Based on these results, the above three natural phenomena can be explained as follows: (1) The assemblage of megadune microrelief and evaporite was caused by the outcropping of water from megadune vadose zone in the form of preferential flow for a long time. Its leading edge differential wind erosion and calcium cemented fine sand layer indicate that water from the megadune vadose zone moves to and recharges the microrelief water along the micro-scale fine sand layer, during which, it features a multiple layer as it is controlled by a vertical dune bedding structure. (2) The small-scale assemblage of megadune vegetation and microrelief indicates that the water from the megadune vadose zone moved laterally and led to vegetation development, and the assemblage of microrelief and vegetation at a slope scale indicates that the vadose zone water presented multilayer enrichment and runoff producing due, to a great extent, to the bedding structures of different spacial locations. (3) The assemblage of lakeside runoff and vegetation is related to the phreatic water recharged by precipitation surrounding the lake, which indicates that the megadune water recharged by precipitation moved to the bottom of the megadune and constituted supply to the lake water. The three assemblages fully demonstrate that the megadune water recharged by precipitation in this desert could recharge the groundwater water and even lake water in the form of preferential flow due to the control of the bedding structure of different scales within the megadune. The results of lake water balance and the occurrence conditions of phreatic water surrounding the lake imply that the precipitation in this desert plays an important role in sustaining the lake. This study provides reliable evidence for revealing the essence of the hydrological cycle and the source of lake water in the Badain Jaran Desert, which indicates that although precipitation is small, it cannot be ignored in arid sandy desert areas.

Enhancing Interferometric SAR Performance Over Sandy Areas: Experience From the TanDEM-X Mission

The TanDEM-X mission is served by two X-band synthetic aperture radar (SAR) satellites, which fly in close orbit formation acting as a large and flexible single-pass radar interferometer. The primary goal of the mission is the creation of a consistent and global digital elevation model (DEM). A very good and reproducible performance has been verified for most of the land masses. In this paper, a detailed performance analysis of TanDEM-X data is presented for sandy desert areas, which show a strong impact on the quality of spaceborne SAR surveys. The influence of several acquisition parameters on SAR and interferometric (InSAR) performance is evaluated by means of statistical analyses as well as long-term repeated acquisitions on defined test sites. Alternative processing approaches aiming at improving the quality of the interferometric products are presented, too. From the obtained analyses, a description of the scattering mechanisms occurring at X-band over sandy surfaces is derived, which allows to plan a dedicated reacquisition of such areas with optimized imaging geometry to improve the quality of the final TanDEM-X DEM.

Diurnal temperature cycle as observed by thermal infrared and microwave radiometers

Land surface temperature (LST) is a key input to physically-based retrieval algorithms of hydrological states and fluxes, and global measurements of LST are provided by many satellite platforms. Passive microwave (MW) observations offer an alternative to thermal infrared (TIR) LST retrieval approaches. Although MW has a lower spatial resolution, its temporal record is more complete as it is more tolerant to clouds. Moreover, merging TIR and MW LST with independent random errors should result in enhanced LST products. Despite these benefits, MW-based LST retrievals are not widely adopted for land applications except as an input to soil moisture retrieval algorithms. This research aims to facilitate expanded use of MW-based LST by formulating a model to explain the systematic differences in comparison to TIR-LST, and quantifying random errors in each datastream. To that end, we compile a 6-year MW-LST dataset over the African continent, combining observations from seven inter-calibrated low orbiting satellites equipped with suitable microwave radiometers. We compare the diurnal timing and amplitude of this dataset to TIR-LST time-series produced by LSA-SAF from the Meteosat Second Generation geostationary satellite. A third independent data source, the skin temperature as modeled by the Modern Era Reanalysis for Research and Applications (MERRA) as produced at NASA's Global Modeling and Assimilation Office, is included in a triple collocation analysis to calculate the random error in the amplitude anomaly. Results suggest that the anomaly in diurnal LST amplitude over much of the African domain can be estimated from TIR and MW with similar levels of random error for clear sky days, except over dry sandy desert areas where the MW sensing depth extends too far below the surface. The temporal sampling advantage of MW, due to higher cloud tolerance in comparison with TIR retrievals, appears to be substantial but will need to be verified by follow-on studies. Overall the results of this study present a significant step forward in reconciling the systematic differences in LST, preparing the way for a global merger of MW and TIR LST time-series.

Field investigation of variation of loading pattern of concrete sleeper due to ballast sandy contamination in sandy desert areas

Sleeper is one of the most important components in a railway track system. Thus, for accurate analysis and design of concrete sleepers, knowledge of imposed loading pattern is necessary. Sandy desert areas are critical regions where loading status of concrete sleeper is different from other areas. In these areas, the influence of flowing sand grains between the ballast aggregates increase the stiffness of ballast layer; consequently, rail support modulus increases, so the received share of total axle load subsequently increases on the sleeper which is placed under the wheel load. On the other hand, the pressure distribution underneath the sleeper changes considerably. In this paper, the results of a field investigation about the variation of rail support modulus and also variation of loading pattern of concrete sleeper followed by the variation of bending moment of sleepers in sandy desert regions were presented.

Field investigation on variation of rail support modulus in ballasted railway tracks

Rail support modulus is an important factor in safety of railway track. This parameter is defined as support force imposing on rail length unit per rail unit displacement in vertical direction. Rail support modulus is important because it affects track performance and maintenance requirements. Both low and large modulus is undesirable. Low modulus of the rail support has been shown to cause differential settlement that then increases maintenance needs. On the other hand, higher value of rail support causes axle load to be distributed on fewer sleepers and therefore received dynamic loads for any sleeper and rail-sleeper fastening will be increased. Sandy desert areas are critical regions about the contamination of ballast. In these areas, flowing sand grains influence between ballast aggregates and increase the stiffness of ballast layer and the rail support modulus. In this paper, the results of a field investigation about the effect of ballast contamination on the values of the rail support modulus in sandy desert areas are presented.

Studies on the biology, chemotherapy and distribution of warble fly in Pakistan

This paper presents data on the prevalence, biology and control of warble fly infestation (WFI) in cattle and goats in Pakistan. A questionnaire for obtaining information on biology and prevalence was circulated amongst field veterinary staff and livestock farmers in all five provinces (Punjab, Sindh, Balochistan, Khyber Pakhtunkhwa [KPK] and Gilgit-Baltistan) and in the Federally Administered Tribal Areas of the country. A total of 1,019 questionnaires were received (Punjab = 296, Sindh = 246, KPK = 318, Balochistan = 151, Gilgit-Baltistan = 8). Warble fly infestation was reported from each province and from the federally administered tribal areas, particularly from hilly, semi-hilly and sandy desert areas (the Cholistan desert, which adjoins the Rehim Yar Khan, Bahawalpur and Bahawalnagar districts, and the Nara area of Sanghar district). Warbles (nodules) started appearing on the backs of the infested animals from September through December and disappeared from October through March. The prevalence of WFI varied from 5% to 75%. It was highest in hilly areas and gradually decreased towards the plains. A map was developed of warble fly-infested areas. Four field trials were conducted to study the efficacy of different drugs indicated for the control of warble fly infestation. A total of 2,094 cattle and 3,876 goats were given five different injectables (avermectins); namely, Ivomec, Endectin, Euvectin, Dectomax and Promectin (ivermectin) during the first three weeks of September. A control group was given normal saline. All the medicines were found to be effective in controlling infestation.

The status of the two Toad-headed Agamas, Phrynocephalus arabicus (Anderson, 1894) and P. maculatus (Anderson, 1872), in Kuwait

This paper clarifies the status of the two species of Phrynocephalus in Kuwait, P. arabicus (Anderson, 1894) and P. maculatus (Anderson, 1872), about which there appears to have been substantial confusion in the past. Both species are now known to occur in this country, with P. arabicus being widespread and locally common in sandy desert areas, but P. maculatus apparently restricted to sabkha and other coastal habitats (including islands). These findings correspond with the known habitat preferences of both species from other parts of the eastern Arabian Peninsula.

Effect of Dormancy Breaking Treatments and Salinity on Seed Germination of Two Desert Shrubs

Hammada (Hammada salicornica Bge) and calligonum (Calligonum intertextum Rech) are dominant shrubs of sandy desert areas of Khuzestan province, in the southwest of Iran, and they are used for sand dune establishment. Seeds of these two species were collected from the wild and subjected to different dormancy breaking treatments (scarification, sulfuric acid, potassium nitrate solution, rinsing and soaking, and controlled temperatures), and to various salinity regimes. Scarification increased the hammada seed germination percentage, decreased germination time, and the rate of germination was significantly lower under saline conditions. The best dormancy breaking treatment for calligonum seeds was stratification at 10°C for 50 days. The optimum temperature for seed germination was 20 and 15°C for hammada and calligonum, respectively. Cold stratified seeds of calligonum germinated to significantly higher percentages than scarified seeds. The highest germination percentage and plumule and radicle lengths of calligonum were obtained at 10 to 15°C. The germination percentage of scarified/stratified seeds of calligonum were lower than nonscarified/nonstratified seeds. Seed dormancy of both species is likely due to have a physiological effect. Seed germination was not affected by salinity up to 5 and 6 dS/m for either species; however, the germination percentage decreased and the time to germination increased with an increase in salinity. Radicle growth decreased more than plumule growth with an increase in salinity in both species.

Germination of Artemisia sphaerocephala (Asteraceae), occurring in the sandy desert areas of Northwest China

Artemisia sphaerocephala is a dominant perennial shrub in large areas of active and stabilized sands of the deserts of northwest China. A. sphaerocephala produces achenes in three colours that germinate at different rates but reach the same final germination percentages. The seeds are covered by a thick pericarp which becomes a mucilaginous layer when wetted and increases in weight 589 times by absorbing water. These achenes float on water for a long time and varying concentrations of salt solutions affect germination. The achenes germinate in light but not in dark. The optimal germination temperature is 25 °C. At 10 °C and 30 °C germination was slow and reached low percentages. Germination was inhibited at 5 °C. The deeper the achenes in sand, the lower and slower their germination. No seedlings emerged from achenes located 2 cm and deeper. However, when the upper layer of sand was removed leaving 0.5 cm, their germination reached the same percentages as the achenes located 0.5 cm deep from the beginning of wetting, but at a faster rate. The higher the sand moisture content, from 1.7% to 14.7%, the higher and earlier the germination From 19.4% moisture content germination was delayed and seedlings remained undeveloped.

Reflectivity of Earth's surface and clouds in ultraviolet from satellite observations

The Total Ozone Mapping Spectrometer (TOMS) on board Nimbus 7 is used to infer the ultraviolet (UV) surface and cloud reflectance at 370 nm. Cloudless surface reflectivity was analyzed on a global basis for all surface types for several months. The UV surface reflectivity varies from 2% for some forest and grassland regions to 14% for some sandy desert areas. A notable exception is the large salt flats of Bolivia, which have a reflectivity of ∼60%. Cloud reflectivity was also analyzed for clouds located at three levels in the atmosphere, as determined by the 11.5‐μm channel of the Temperature Humidity Infrared Radiometer. Average cloud reflectivity at 370 nm ranges from 52% for low clouds (tops <2 km) to 76% for high clouds (tops > 7 km at the equator, decreasing to >4 km at poles).

Distribution and Habitats of Turtles in New Mexico

Distributional and habitat data on nine species of New Mexico turtles are presented by locality maps and text. The state's turtle fauna consists of Chelydra serpentina, Kinosternon flavescens, K. sonoriense, Terrapene ornata, Chry- semys picta, Pseudemys concinna, P. scripta elegans, P. scripta gaigae, Trionyx muticus, T. spiniferus emoryi, and T. spiniferus hartwegi. Active study of New Mexico turtles began in 1961 and since that time approximately 700 specimens have been added to the University of New Mexico collections. Specimens from other collections and published accounts were included in the locality maps for each species. The aquatic turtles are primarily distributed along the state's princi- pal river systems but individual species show marked differences in their ability to survive away from permanent waters. The single terrestrial species, Terrapene ornata, is widely distributed in the state below about 6,600 feet. Dense populations of Terrapene occur in the grasslands of northeastern New Mexico as well as in relatively dry, sandy desert areas in the southeast but were not found on steep, rocky, mountain slopes, in dense woodlands, or in seemingly suitable habitats in northwestern New Mexico. Much of the herpetological collecting in the southwest prior to 1900 was done in conjunction with United States governmental surveying expeditions or military activities. These explorations had accompany- ing naturalists, who amassed sizeable collections, and their names were often used in the description of the animals they collected. Turtles, because of difficulty in collecting without specialized equip- ment, were absent or poorly represented in these early collections. Van Denburgh (1924), providing the first major contribution to the knowledge of the state herpetofauna, listed five species of turtles. The

The Formation of Fine Particles in Sandy Deserts and the Nature Of 'Desert' Loess

ABSTRACT Loess consists chiefly of quartz particles with diameters of about 20-50µ. It is commonly thought to have formed in periglacial areas and in deserts. Smalley (1966b) has suggested that direct glacial grinding could produce suitable particles. The existence of dust storms suggests that fine particles also form in hot, sandy deserts; these could be the result of interparticle contacts where a certain critical kinetic energy is involved. There are no loess deposits within sandy desert areas, but they may occur at the desert margins. The major loess provinces to which a desert origin has been ascribed either are not true loess or are explicable in terms of glacial origin. Of the minor deposits, only that of the Negev seems to have a well established desert origin. The quartz particles in the Negev deposit probably formed by simple impact. This mechanism does not seem adequate for the Chinese loess, and it is suggested that the widespread Pleistocene glaciation of China was responsible for the bulk of the fine particles. Thus although loess particles can form mechanically in deserts, they have not done so on a scale sufficient to produce major loess deposits. Desert loess deposits should be distinguishable from glacial oess deposits by their size and their mineralogical nature. Stresses produced by temperature changes can break rocks provided that the rock particles are not below a certain critical size. Most quartz is introduced into the sedimentary system as sand-size particles (about 500µ); if the critical thermal break size is above 500µ, then the thermal breakage process will not produce loess-size particles.