Search results for: sandy desert

Authors: Milad Alizadeh Galdiani, Navid Sabet, Mohamad Ali Mohit, Fatemeh Palizdar

Abstract:

Railway as one of the most important transportation modes, passes through ‎various areas with different conditions ‎inevitably, and in many countries such as ‎China, United States, Australia, and Iran, it passes through sandy ‎desert areas. One ‎of the main problems in these areas is the movement of sand, causing various ‎damages ‎to ballasted railway track such as corrosion in the railway fastening system. ‎The soil composition of some desert areas like Fahraj in Iran consists of sand ‎and ‎salt. Due to the movement of sand and corrosive ions of salt, the fastening system ‎of the railway is ‎corroded, which, in turn, reduces the thickness of the components ‎and their life span.‎ In this research, the Nano-coating for fastening system of ‎the railway is ‎introduced, and its performance has been investigated in both ‎laboratory and field tests. The Nano-coating of ‎the fastening system consists of zinc-rich, epoxy, polyurethane, and additive, which is produced through ‎Nano ‎technology. This layer covers the surface of the fastening system and ‎prohibits the chemical reactions, which result in ‎corrosion. The results of ‎Electrochemical Impedance Spectroscopy (EIS) ‎indicate that corrosion resistance ‎increases 315 times by using nano-coating, salt spray test results demonstrate that ‎nano-coated components remained intact after 1000 hours.‎

Keywords: ballasted railway, Nano-coating, railway fastening system, sandy desert

Procedia PDF Downloads 88

Authors: Modi M. Ahmed, Noor Al-Dousari, Ali M. Al-Dousari

Abstract:

Cornulaca aucheri is an annual herb consider as disturbance indicator currently visible and widely distributed in disturbed lands in Liyah area. Such area is suffered from severe land degradation due to multiple interacting factors such as, overgrazing, gravel and sand quarrying, military activities and natural process. The restoration program is applied after refilled quarries sites and levelled the surface irregularities in order to rehabilitate the natural vegetation and wildlife to its original shape. During the past 10 years of rehabilitation, noticeable greenery healthy cover of Cornulaca sp. are shown specially around artificial lake and playas. The existence of such species in high density it means that restoration program has succeeded and transit from bare ground state to Cornulaca and annual forb state. This state is lower state of Range State Transition Succession model, but it is better than bare soil. Cornulaca spp is native desert plant grows in arid conditions on sandy, stony ground, near oasis, on sand dunes and in sandy depressions. The sheep and goats are repulsive of it. Despite its spiny leaves, it provides good grazing for camels and is said to increase the milk supply produced by lactating females. It is about 80 cm tall and has stems that branched from the base with new faster greenery growth in the summer. It shows good environmental potential to be managed as natural types used for the restoration of degraded lands in desert areas.

Keywords: land degradation, range state transition succession model, rehabilitation, restoration program

Procedia PDF Downloads 326

Authors: Ahmed Ali Samejo, Riffat Sultana

Abstract:

Pakistan has the sandy Thar Desert in the eastern area, which share border line with India and has exotic fauna and flora, the livelihood of native people rely on livestock and rain fed cultivated fields. The climate of Thar Desert is very harsh and stressful due to frequent drought and very little rainfall, which may occur during monsoon season in the months of July to October and temperature is high, and wind speed also increases in April to June. Schistocerca gregaria is a destructive pest of vegetation from Mauritania to the border line of Pakistan and India. Sometimes they produce swarms which consume all plant where ever they land down and cause the loss in agro-economy of the world. During the recent study, we observed that vegetation was not unique throughout the Thar Desert in the year 2015, because the first spell of rainfall showered over all areas of the Thar Desert in July. However, the second and third spell of rain was confined to village Mahandre jo par and surroundings from August to October. Consequently, vegetation and cultivated crops grew up specially bajra crop (Pennistum glaucum). The climate of Mahandre jo par and surroundings became favorable for S.gregaria, and remaining areas of Thar Desert went hostile. Therefore desert locust attracted to the pleasant area (Mahandre jo par and surroundings) and gradually concentrated, increased reproductive activities, but did not gregarize due to the harvest of bajra crop and the onset of the winter season with an immediate decrease in temperature. An outbreak was near to come into existence, and thereupon conditions become stressful for hoppers to continue further development. Afore mentioned was one reason behind hurdle to the outbreak, another reason might be that migration and concentration of desert locust took place at the end of the season, so climate becomes unfavorable for hoppers, due to dryness of vegetation. Soils also become dry, because rainfall was not showered in end of the season, that’s why eggs that were deposited in late summer were desiccated. This data might be proved fruitful to forecast any outbreak update in future.

Keywords: agro-economy, destructive pest, climate, outbreak, vegetation

Procedia PDF Downloads 145

Authors: Olusegun Paul Adesanya, Oluwatomilade Olominu, Olusegun Idowu

Abstract:

This study investigates new dangers that West African migrants travelling through the Sahara Desert to Europe contend with. COVID-19 has left an unprecedented impact on all aspects of global politics, migration inclusive. In turn, limitations to migration have drastically increased, especially the stricter visa application measures set by European countries. This intensified attempts at crisscrossing the desert to Europe. In turn, several migrants used the Sahara as the highway to Europe. While some persons successfully travelled through the desert-scape, several others were unsuccessful. Notwithstanding the negative experiences of previous migrants, several other nationals across the region have plans to travel through the desert to Europe. As such, this study employs a mixed method of research reliant on qualitative and quantitative methods of data gathering and analysis. The study holds that there are new dangers to the aspirations of West Africans travelling to Europe through the Sahara and the Mediterranean Sea.

Keywords: migrants, Sahara Desert, West Africa, crisscrossing, dangers, irregular migration

Procedia PDF Downloads 156

Authors: A. Nazeri, R. Ziaie Moayed, H. Ghiasinejad

Abstract:

The present research has been performed to investigate the effect of base course application on load-settlement characteristics of sandy subgrade using plate load test. The main parameter investigated in this study was the subgrade reaction coefficient. The model tests were conducted in a 1.35 m long, 1 m wide, and 1 m deep steel test box of Imam Khomeini International University (IKIU Calibration Chamber). The base courses used in this research were in three different thicknesses of 15 cm, 20 cm, and 30 cm. The test results indicated that in the case of using base course over loose sandy subgrade, the values of subgrade reaction coefficient can be increased from 7  to 132 , 224 , and 396  in presence of 15 cm, 20 cm, and 30 cm base course, respectively.

Keywords: modulus of subgrade reaction, plate load test, base course, sandy subgrade

Procedia PDF Downloads 215

Authors: W. S. Mohamed, A. A. Hammam

Abstract:

Sandy soils under arid and semi-arid conditions are characterized by poor physical and biochemical properties such as low water retention, rapid organic matter decomposition, low nutrients use efficiency, and limited crop productivity. Addition of organic amendments is crucial to develop soil properties and consequently enhance nutrients use efficiency and lessen organic carbon decomposition. Two years field experiments were developed to investigate the feasibility of using poultry manure and its derived biochar integrated with different levels of N fertilizer as a soil amendment for newly reclaimed sandy soils in Western Desert of El-Minia Governorate, Egypt. Results of this research revealed that poultry manure and its derived biochar addition induced pronounced effects on soil moisture content at saturation point, field capacity (FC) and consequently available water. Data showed that application of poultry manure (PM) or PM-derived biochar (PMB) in combination with inorganic N levels had caused significant changes on a range of the investigated sandy soil biochemical properties including pH, EC, mineral N, dissolved organic carbon (DOC), dissolved organic N (DON) and quotient DOC/DON. Overall, the impact of PMB on soil physical properties was detected to be superior than the impact of PM, regardless the inorganic N levels. In addition, the obtained results showed that PM and PM application had the capacity to stimulate vigorous growth, nutritional status, production levels of wheat and sorghum, and to increase soil organic matter content and N uptake and recovery compared to control. By contrast, comparing between PM and PMB at different levels of inorganic N, the obtained results showed higher relative increases in both grain and straw yields of wheat in plots treated with PM than in those treated with PMB. The interesting feature of this research is that the biochar derived from PM increased treated sandy soil organic carbon (SOC) 1.75 times more than soil treated with PM itself at the end of cropping seasons albeit double-applied amount of PM. This was attributed to the higher carbon stability of biochar treated sandy soils increasing soil persistence for carbon decomposition in comparison with PM labile carbon. It could be concluded that organic manures applied to sandy soils under arid and semi-arid conditions are subjected to high decomposition and mineralization rates through crop seasons. Biochar derived from organic wastes considers as a source of stable carbon and could be very hopeful choice for substituting easily decomposable organic manures under arid conditions. Therefore, sustainable agriculture and productivity in newly reclaimed sandy soils desire one high rate addition of biochar derived from organic manures instead of frequent addition of such organic amendments.

Keywords: biochar, dissolved organic carbon, N-uptake, poultry, sandy soil

Procedia PDF Downloads 116

Authors: Mohammed Sherzad

Abstract:

The Sahara desert covers third of the total surface of Africa with a quarter of this area within the national boundaries of Algeria. Sand drift and deposition is considered one of the major factors of the desertification process in the area. It is estimated that a third of the world's hot arid lands are covered by aeolian sand deposits, forming extensive sand bedforms. The Gourrara region in the Grand Erg Occidental (west of Algerian Sahara) and the region of Souf in the Grand Erg Oriental (east of Algerian Sahara) have been chosen as case studies. These were significant cultural and trading centers for many centuries despite their remote location and their harsh desert environment particularly solar radiation and sand drift and deposition. The architecture of the sustained vernacular settlements in each of the two regions has unique design features for this environment. So do the irrigation systems used - palm groves and the foggara system for capturing and distributing groundwater. However, the ecological balance which enabled the Saharans to live with the desert has been upset. New buildings often use technology based on models imported or imposed from areas that climatically have little in common. These make the inhabitants live ‘in the desert’ rather than ‘with the desert’. This paper will describe the qualities of the vernacular architecture and demonstrate its effectiveness and adaptability to the region’s harsh desert environment in comparison with contemporary buildings. Developing design guides and approaches based on lessons from the traditional architecture is important to ensure sustained livelihoods of the inhabitants in these areas.

Keywords: vernacular architecture, desert architecture, hot climate, aeolian sand deposition

Procedia PDF Downloads 435

Authors: Sujo Meghwar, Zulfqar Ali laghari, Kanji Harijan, Muhib Ali Lagari, G. M. Mastoi, Ali Mohammad Rind

Abstract:

Thar Desert is the most populous Desert of the world. Climate variation in Thar Desert has induced an increase in the magnitude of drought. The variation in climate variation has caused a decrease in natural vegetations. Some plant species are eliminated forever. We have applied the SPI (standardized precipitation index) climate model to investigate the drought induced by climate change. We have gathered the anthropogenic response through a developed questionnaire. The data was analyzed in SPSS version 18. The met-data of two meteorological station elaborated by the time series has suggested an increase in temperature from 1-2.5 centigrade, the decrease in rain fall rainfall from 5-25% and reduction in humidity from 5-12 mm in the 20th century. The anthropogenic responses indicate high impact of climate change on human life and vegetations. Triangle data, we have collected, gives a new insight into the understanding of an association between climate change, drought and human activities.

Keywords: Thar desert, human impact, vegetations, temperature, rainfall, humidity

Procedia PDF Downloads 368

Authors: R. Ziaie Moayed, M. Hamidzadeh

Abstract:

The use of waste rubber chips not only can be of great importance in terms of the environment, but also can be used to increase the shear strength of soils. The purpose of this study was to evaluate the variation of the internal friction angle of liquefiable sandy soil using waste rubber chips. For this purpose, the geotechnical properties of unmodified and modified soil samples by waste lining rubber chips have been evaluated and analyzed by performing the triaxial consolidated drained test. In order to prepare the laboratory specimens, the sandy soil in part of Rudsar shores in Gilan province, north of Iran with high liquefaction potential has been replaced by two percent of waste rubber chips. Samples have been compressed until reaching the two levels of density of 15.5 and 16.7 kN/m³. Also, in order to find the optimal length of chips in sandy soil, the rectangular rubber chips with the widths of 0.5 and 1 cm and the lengths of 0.5, 1, and 2 cm were used. The results showed that the addition of rubber chips to liquefiable sandy soil greatly increases the shear resistance of these soils. Also, it can be seen that decreasing the width and increasing the length-to-width ratio of rubber chips has a direct impact on the shear strength of the modified soil samples with rubber chips.

Keywords: improvement, shear strength, internal friction angle, sandy soil, rubber chip

Procedia PDF Downloads 118

Authors: Seyed Abolhasan Naeini, Mohammad Mahdi Shojaedin

Abstract:

Oil leakage from the pipelines and the tanks carrying them, or during oil extraction, could lead to the changes in the characteristics and properties of the soil. In this paper, conducting a series of experimental cyclic triaxial tests, the effects of oil contamination on the liquefaction potential of sandy soils is investigated. The studied specimens are prepared by mixing the Firoozkuh sand with crude oil in 4, 8 and 12 percent by soil dry weight. The results show that the oil contamination up to 8% causes an increase in the soil liquefaction resistance and then with increase in the contamination, the liquefaction resistance decreases.

Keywords: cyclic triaxial test, liquefaction resistance, oil contamination, sandy soil

Procedia PDF Downloads 490

Authors: Hai Zhou, Wenzhi Zhao

Abstract:

Water is one of the most important factors limiting plant growth and development in desert ecosystems. In order to understand how desert shrubs cope with variation in water sources over time, it is important to understand plant–water relations in desert-oasis ecotone. We selected the typical desert shrubs: Nitraria sibirica, Calligonum mongolicum and Haloxylon ammodendron of 5-, 10-, 20- and 40-year old as the research species, to study the seasonal variation of plant water sources and response to precipitation in the desert-oasis ecotone of Linze, Northwestern China. We examined stable isotopic ratios of oxygen (δ18O) in stem water of desert shrubs as well as in precipitation, groundwater, and soil water in different soil layers and seasons to determine water sources for the shrubs. We found that the N. sibirica and H. ammodendron of 5-, 10-year old showed significant seasonal variation characteristics of δ18O value of stem water and water sources. However, the C. mongolicum and 20- and 40-year H. ammodendron main water sources were from deep soil water and groundwater, and less response to precipitation pulse. After 22.4 mm precipitation, the contribution of shallow soil water (0-50cm) to the use of N. sibirica increased from 6.7% to 36.5%; the C. mongolicum rarely use precipitation that were about 58.29% and 23.51%, absorbed from the deep soil water and groundwater; the contribution of precipitation to use of H. ammodendron had significantly differences among the four ages. The H. ammodendron of 5- and 10-year old about 86.3% and 42.5% water sources absorbed from the shallow soil water after precipitation. However, the contribution to 20- and 40-year old plant was less than 15%. So, the precipitation was one of the main water sources for desert shrubs, but the species showed different water utilization. We conclude that the main water source of the N. sibirica and H. ammodendron of 5-, 10-year was soil water recharged by precipitation, but the deeply rooted H. ammodendron of 20‐ and 40‐year‐old and the C. mongolicum have the ability to exploit a deep and reliable water source.

Keywords: water use pattern, water resource, stable isotope, seasonal change, precipitation pulse

Procedia PDF Downloads 397

Authors: Massoud Farag Abouklaish

Abstract:

The main aim of the present study is to investigate and classify the particle size distribution of sandy soils in Libya. More than fifty soil samples collected from many regions in North, West and South of Libya. Laboratory sieve analysis tests performed on disturbed soil samples to determine grain size distribution. As well as to provide an indicator of general engineering behavior and good understanding, test results are presented and analysed. In addition, conclusions, recommendations are made.

Keywords: Libya, grain size, sandy soils, sieve analysis tests

Procedia PDF Downloads 565

Authors: Hisham Mortada

Abstract:

For thousands of years mud houses have represented the practical wisdom and spirituality of people, particularly those of desert regions, who learned how to use local materials to build homes that fitted the environmental and cultural conditions which they lived in. As a case study, the central region of Saudi Arabia exhibits a tradition of earth architecture that is unique in style, culture and sustainability. Aiming to contribute towards the local debate of the suitability of the traditional mud architecture for today’s lifestyle of Saudis, this paper explores the sustainable nature of the traditional adobe architecture of this hot arid region from environmental, social and technical points of view.

Keywords: desert architecture, alternative materials, Saudi Arabia, arid climate, green architecture

Procedia PDF Downloads 340

Authors: Ali Montazar

Abstract:

California and the Colorado River Basin are facing increasing uncertainty concerning water supplies. The Colorado River is the main source of irrigation water in the low desert of California. Currently, due to an increasing water-use competition and long-term drought at the Colorado River Basin, efficient use of irrigation water is one of the highest conservation priorities in the region. This study aims to present some of current irrigation technologies and management approaches in the low desert and assess the viability and potential of these water management practices. The results of several field experiments are used to assess five water conservation practices of sub-surface drip irrigation, automated surface irrigation, sprinkler irrigation, tail-water recovery system, and deficit irrigation strategy. The preliminary results of several ongoing studies at commercial fields are presented, particularly researches in alfalfa, sugar beets, kliengrass, sunflower, and spinach fields. The findings indicate that all these practices have significant potential to conserve water (an average of 1 ac-ft/ac) and enhance the efficiency of water use (15-25%). Further work is needed to better understand the feasibility of each of these applications and to help maintain profitable and sustainable agricultural production system in the low desert as water and labor costs, and environmental issues increase.

Keywords: automated surface irrigation, deficit irrigation, low desert of California, sprinkler irrigation, sub-surface drip irrigation, tail-water recovery system

Procedia PDF Downloads 116

Authors: Jacques M. Berner, Monja Gerber, Gillian L. Maggs-Kolling, Stuart J. Piketh

Abstract:

The enigmatic melon species, Acanthosicyos horridus Welw. ex Hook. f., locally known as !nara, is endemic to the hyper-arid Namib Desert, where it thrives in sandy dune areas and dry river banks. The Namib Desert is characterized by extreme weather conditions which include high temperatures, very low rainfall, and extremely dry air. Plant and animals that have made the Namib Dessert their home are dependent on non-rainfall water inputs, like fog, dew and water vapor, for survival. Fog is believed to be the most important non-rainfall water input for most of the coastal Namib Desert and is a life line to many Namib plants and animals. It is commonly assumed that the !nara plant is adapted and dependent upon coastal fog events. The !nara plant shares many comparable adaptive features with other organisms that are known to exploit fog as a source of moisture. These include groove-like structures on the stems and the cone-like structures of thorns. These structures are believed to be the driving forces behind directional water flow that allow plants to take advantage of fog events. The !nara-fog interaction was investigated in this study to determine the dependence of !nara on these fog events, as it would illustrate strategies to benefit from non-rainfall water inputs. The direct water uptake capacity of !nara shoots was investigated through absorption tests. Furthermore, the movement and behavior of fluorescent water droplets on a !nara stem were investigated through time-lapse macrophotography. The shoot water potential was measured to investigate the effect of fog on the water status of !nara stems. These tests were used to determine whether the morphology of !nara has evolved to exploit fog as a non-rainfall water input and whether the !nara plant has adapted physiologically in response to fog. Chlorophyll a fluorescence was used to compare the photochemical efficiency of !nara plants on days with fog events to that on non-foggy days. The results indicate that !nara plants do have the ability to take advantage of fog events as commonly believed. However, the !nara plant did not exhibit visible signs of drought stress and this, together with the strong shoot water potential, indicates that these plants are reliant on permanent underground water sources. Chlorophyll a fluorescence data indicated that temperature stress and wind were some of the main abiotic factors influencing the plants’ overall vitality.

Keywords: Acanthosicyos horridus, chlorophyll a fluorescence, fog, foliar absorption, !nara

Procedia PDF Downloads 118

Authors: Soheir El-Shazly, Gouda Abdelgawad, Yasser Salama, Dina Sayed

Abstract:

Abstract- The Late Eocene rocks (Qasr El-Sagha ) Formation, north east of Birket Qarun in Fayum area of Egypt reveals 6 Ichnogenera Thalassinoides Ehrenberg, 1944, Ophiomorpha Lundgren (1891), Skolithos Haldemann (1840), Diplocraterion Torell, 1870, Arenicolites Salter, 1857 and Planolites Nicholson, 1873. These Ichnogenera are related to Skolithos ichnofacies of typical sandy shoreline environment, only the ichnogenus Planolites is related to Cruziana ichnofacies, which occurs in somewhat deeper water than the Skolithos ichnofacies. Four microfacies types have been distinguished from the study sections, Mudstone, Sandy micrite (wackstone), Sandy dolomitic ferruginous biomicrite (Packstone), Sandy glauconitic biomicrite (packstone). The ichnofacies and the microfacies study indicates that the study area was deposited in shelf lagoon with open circulation environment

Keywords: Egypt, Fayum, icnofacies, late eocene, microfacies

Procedia PDF Downloads 180

Authors: Abdulah Hamads Alatiah

Abstract:

The green architecture represents the essence of the sustainability process and the fundamental rule in the desert areas' reconstruction seeking to maintain the environmental balance. This study is based on the analytical descriptive approach, to extract the objectives of green architecture in the desert areas, and reveal the most important principles that contribute to highlight its economic, social, and environmental importance, in addition to standing on the most important technical standards that can be relied upon to deal with its environmental problems. The green architecture aims: making use of the alternative energy, reducing the conventional energy consumption, addressing its negative effects, adapting to the climate, innovation in design, providing the individuals' welfare and rationalizing the use of the available resources to maintain its environmental sustainability.

Keywords: green architecture, the warm-dry climate, natural lighting, environmental quality, renewable energy, weather changes

Procedia PDF Downloads 291

Authors: Muna A. Eissawi, Safaa Abed Elfataah, Haytham Hago, Fatima E Abukunna, Ibtisam Amin Goreish, Nahid Gornas

Abstract:

The study examined and analyzed the genetic diversity of DRB1locus of exon 2 of major histocompatibility complex of Sudanese desert sheep using PCR-RFLP and DNA sequencing. Five hundred samples belonging to five ecotypes of Desert Sudanese sheep (Abrag (Ab), Ashgar (Ash), Hamari (H), Kabashi (K) and Watish (W) were included. Amplification of exon 2 of the DRB1 gene yielded (300bp) amplified product in different ecotypes. Nine different digestion patterns corresponding to Five distinct alleles were observed with Rsa1 digestion. Genotype (ag) was the most common among all ecotypes, with a percentage comprised (40.4 %). The Hardy-Weinberg equilibrium (HWE) test showed that the studied ecotypes have significantly deviated from the theoretical proportions of Rsa1 patterns; probability values of the Chi-square test for HWE for MHC-DRB1 gene in SDS were 0.00 in all ecotypes. The constructed phylogenetic tree revealed the relation of 22 Sudanese isolates with each other and showed the shared sequences with 47 published foreign sequences randomly selected from different geographic regions. The results of this study highlight the effect of heterozygosity of MHC genes of the Desert sheep of Sudan which may clarify some of genetic back ground of their disease resistance and adaptation to environment.

Keywords: desert sheep, MHC, Ovar-DRB1, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP)

Procedia PDF Downloads 30

Authors: Hazem Bunkheila

Abstract:

Ghadames is an oasis on the edge of the Sahara Desert in southwestern Libya at the border with Algeria and Tunisia. It is the oldest oasis in the world that provides a fascinating example of traditional urban in the desert environment. The urban of the small city is considered a genuine adaptation to the harsh desert climate. The historic city of Ghadames remained unaffected by the rapid after oil changes. That makes it a good field to study sustainable, vernacular, earth architecture and urban design. The aim of this paper is to investigate the urban structure, concept, and fabric of the old oasis. The research also surveys the environmental considerations in the city that shades the sustainable features in this traditional residential area. In addition, the paper addresses the modern applications in the new city of Ghadams and sides of success and failure compared to the traditional urban fabric.

Keywords: dessert climate design, Ghadames, sustainable urban design, traditional urban design

Procedia PDF Downloads 328

Authors: Abou Bakr Merdji, Alaa Mhawish, Xiaofeng Xu, Chunsong Lu

Abstract:

The characteristics of optical and microphysical properties of aerosols near deserts are analyzed using 11 AErosol RObotic NETwork (AERONET) sites located in 6 major desert areas (the Sahara, Arabia, Thar, Karakum, Taklamakan, and Gobi) between 1998 and 2021. The regional mean of Aerosol Optical Depth (AOD) (coarse AOD (CAOD)) are 0.44 (0.187), 0.38 (0.26), 0.35 (0.24), 0.23 (0.11), 0.20 (0.14), 0.10 (0.05) in the Thar, Arabian, Sahara, Karakum, Taklamakan and Gobi Deserts respectively, while an opposite for AE and Fine Mode Fraction (FMF). Higher extinctions are associated with larger particles (dust) over all the main desert regions. This is shown by the almost inversely proportional variations of AOD and CAOD compared with AE and FMF. Coarse particles contribute the most to the total AOD over the Sahara Desert compared to those in the other deserts all year round. Related to the seasonality of dust events, the maximum AOD (CAOD) generally appears in summer and spring, while the minimum is in winter. The mean values of absorbing AOD (AAOD), Absorbing AE (AAE), and the Single Scattering Albedo (SSA) for all sites ranged from 0.017 to 0.037, from 1.16 to 2.81 and from 0.844 to 0.944, respectively. Generally, the highest absorbing aerosol load are observed over the Thar, followed by the Karakum, the Sahara, the Gobi, and then the Taklamakan Deserts, while the largest absorbing particles are observed in the Sahara followed by Arabia, Thar, Karakum, Gobi, and the smallest over the Taklamakan Desert. Similar absorption qualities are observed over the Sahara, Arabia, Thar, and Karakum Deserts, with SSA values varying between 0.90 and 0.91, whereas the most and least absorbing particles are observed at the Taklamakan and the Gobi Deserts, respectively. The seasonal AAODs are distinctly different over the deserts, with parts of Sahara and Arabia, and the Dalanzadgad sites experiencing the maximum in summer, the Southern Sahara, Western Arabia, Jaipur, and Dushanbe in winter, while the Eastern Arabia and the Muztagh Ata in autumn. AAOD and SSA spectra are consistent with dust-dominated conditions that resulted from aerosol typing (dust and polluted dust) at most deserts, with a possible presence of other absorbing particles apart from dust at Arabia, the Taklamakan, and the Gobi Desert sites.

Keywords: sahara, AERONET, desert, dust belt, aerosols, optical properties

Procedia PDF Downloads 47

Authors: Syed Ahsan, Saleh Alshomrani, Ishtiaq Rasool, Ali Hassan

Abstract:

In this oral presentation, we will provide an overview of the technical and semantic architecture of a desert border security and critical infrastructure protection security system. Modern border security systems are designed to reduce the dependability and intrusion of human operators. To achieve this, different types of sensors are use along with video surveillance technologies. Application of these technologies in a harsh desert environment of Saudi Arabia poses unique challenges. Environmental and geographical factors including high temperatures, desert storms, temperature variations and remoteness adversely affect the reliability of surveillance systems. To successfully implement a reliable, effective system in a harsh desert environment, the following must be achieved: i) Selection of technology including sensors, video cameras, and communication infrastructure that suit desert environments. ii) Reduced power consumption and efficient usage of equipment to increase the battery life of the equipment. iii) A reliable and robust communication network with efficient usage of bandwidth. Also, to reduce the expert bottleneck, an ontology-based intelligent information systems needs to be developed. Domain knowledge unique and peculiar to Saudi Arabia needs to be formalized to develop an expert system that can detect abnormal activities and any intrusion.

Keywords: border security, sensors, abnormal activity detection, ontologies

Procedia PDF Downloads 450

Authors: Saad M. Howladar, Ashraf Sh. Osman, Mostafa M. Rady, Hassan S. Al-Zahrani

Abstract:

The effects of soil inoculation with phosphorien-containing Phosphate-Dissolving Bacteria (PDB) and/or magnesium (Mg) foliar application at the rates of 0, 0.5 and 1mM on growth, green pod and seed yields, and chemical constituents of Pisum sativum L. grown on a sandy calcareous soil were investigated. Results indicated that PDB and/or Mg significantly increased shoot length, number of branches plant–1, total leaf area plant–1 and canopy dry weight plant–1, leaf contents of pigments, soluble sugars, free proline, nitrogen, phosphorus, potassium, magnesium, and calcium, and Ca/Na ratio, while leaf Na content was reduced. PDB and/or Mg also increased green pod and seed yields. We concluded that PDB and Mg have pronounced positive effects on Pisum sativum L. plants grown on sandy calcareous soil. PDB and Mg, therefore, have the potential to be applied for various crops to overcome the adverse effects of the newly-reclaimed sandy calcareous soils.

Keywords: bio-p-fertilizer, mg foliar application, newly-reclaimed soils, Pisum sativum L.

Procedia PDF Downloads 330

Authors: F. Allag, S. Bouharati, M. Belmahdi, R. Zegadi

Abstract:

The rapid expansion of deserts in recent decades as a result of human actions combined with climatic changes has highlighted the necessity to understand biological processes in arid environments. Whereas physical processes and the biology of flora and fauna have been relatively well studied in marginally used arid areas, knowledge of desert soil micro-organisms remains fragmentary. The objective of this study is to conduct a diversity analysis of bacterial communities in unvegetated arid soils. Several biological phenomena in hot deserts related to microbial populations and the potential use of micro-organisms for restoring hot desert environments. Dry land ecosystems have a highly heterogeneous distribution of resources, with greater nutrient concentrations and microbial densities occurring in vegetated than in bare soils. In this work, we found it useful to use techniques of artificial intelligence in their treatment especially artificial neural networks (ANN). The use of the ANN model, demonstrate his capability for addressing the complex problems of uncertainty data.

Keywords: desert soil, climatic changes, bacteria, vegetation, artificial neural networks

Procedia PDF Downloads 365

Authors: Saeed Talamkhani, Seyed Abolhassan Naeini

Abstract:

In recent years, the occurrence of several liquefactions in sandy soils containing various values of clay content has shown that in addition to silty sands, clayey sands are also susceptible to liquefaction. Therefore, it is necessary to investigate the properties of these soil compositions and their behavioral characteristics. This paper presents the effect of clay fines on the undrained shear strength of sands at various confining pressures. For this purpose, a series of unconsolidated undrained triaxial shear tests were carried out on clean sand and sand mixed with 5, 10, 15, 20, and 30 percent of clay fines. It was found that the presence of clay particle in sandy specimens change the dilative behavior to contraction. The result also showed that increasing the clay fines up to 10 percent causes to increase the potential for liquefaction, and decreases it at higher values fine content. These results reveal the important role of clay particles in changing the undrained strength of the sandy soil.

Keywords: clayey sand, liquefaction, triaxial test, undrained shear strength

Procedia PDF Downloads 157

Authors: Reza Ziaie Moayed, Javad Shamsi Soosahab

Abstract:

The bearing capacity of shallow foundations is one of the interesting subjects in geotechnical engineering. Soil improvement by geosynthetic reinforcements is a modern method used in different projects to improve the bearing capacity of foundations. In this paper, numerical study is adopted to investigate the effect of geogrid soil reinforcement on shallow foundation behavior resting on anisotropic sand with using a finite element limit analysis software. The effect of the ratio of horizontal elastic modulus with respect to vertical elastic modulus (EH/EV) investigates on bearing capacity of foundations. The results illustrate that in sandy soils, the anisotropic ratio of elastic modulus (EH/EV) has notable effect on bearing capacity of shallow foundations. Also, based on the results of this study, it was concluded that geogrid could be used as soil reinforcement elements to improve the bearing of sandy soils and reduce its settlement possible remarkably.

Keywords: shallow foundations, bearing capacity, numerical study, soil anisotropy, geogrid

Procedia PDF Downloads 116

Authors: Eman Ghoneim

Abstract:

The Arabian deserts include some of the driest areas on Earth. Yet, its landforms reserved a record of past wet climates. During humid phases, the desert was green and contained permanent rivers, inland deltas and lakes. Some of their water would have seeped and replenished the groundwater aquifers. When the wet periods came to an end, several thousand years ago, the entire region transformed into an extended band of desert and its original fluvial surface was totally covered by windblown sand. In this work, radar and thermal infrared images were used to reveal numerous hidden surface/subsurface features. Radar long wavelength has the unique ability to penetrate surface dry sands and uncover buried subsurface terrain. Thermal infrared also proven to be capable of spotting cooler moist areas particularly in hot dry surfaces. Integrating Radarsat images and GIS revealed several previously unknown paleoriver and lake basins in the region. One of these systems, known as the Kufrah, is the largest yet identified river basin in the Eastern Sahara. This river basin, which straddles the border between Egypt and Libya, flowed north parallel to the adjacent Nile River with an extensive drainage area of 235,500 km2 and massive valley width of 30 km in some parts. This river was most probably served as a spillway for an overflow from Megalake Chad to the Mediterranean Sea and, thus, may have acted as a natural water corridor used by human ancestors to migrate northward across the Sahara. The Gilf-Kebir is another large paleoriver system located just east of Kufrah and emanates from the Gilf Plateau in Egypt. Both river systems terminate with vast inland deltas at the southern margin of the Great Sand Sea. The trends of their distributary channels indicate that both rivers drained to a topographic depression that was periodically occupied by a massive lake. During dry climates, the lake dried up and roofed by sand deposits, which is today forming the Great Sand Sea. The enormity of the lake basin provides explanation as to why continuous extraction of groundwater in this area is possible. A similar lake basin, delimited by former shorelines, was detected by radar space data just across the border of Sudan. This lake, called the Northern Darfur Megalake, has a massive size of 30,750 km2. These former lakes and rivers could potentially hold vast reservoirs of groundwater, oil and natural gas at depth. Similar to radar data, thermal infrared images were proven to be useful in detecting potential locations of subsurface water accumulation in desert regions. Analysis of both Aster and daily MODIS thermal channels reveal several subsurface cool moist patches in the sandy desert of the Arabian Peninsula. Analysis indicated that such evaporative cooling anomalies were resulted from the subsurface transmission of the Monsoonal rainfall from the mountains to the adjacent plain. Drilling a number of wells in several locations proved the presence of productive water aquifers confirming the validity of the used data and the adopted approaches for water exploration in dry regions.

Keywords: radarsat, SRTM, MODIS, thermal infrared, near-surface water, ancient rivers, desert, Sahara, Arabian peninsula

Procedia PDF Downloads 212

Authors: Nejib Turki, Karima Kouki Khalfallah

Abstract:

The effect of six treatments of organic amendments were evaluated on a sandy soil in the region of Soukra in Tunisia. T1: cattle manure 55 t.ha-1, T2: commercial compost from Germany to 1 t.ha-1, T3: a mixture of 27.5 t.ha-1 of T1 with 0.5 t. ha-1 of T2, T4: commercial compost from France 2 t.ha-1, T5: a Tunisian commercial compost to 10 t.ha-1 and T0: control without treatment. The nitrogen in the soil increase to 0.029 g.kg-1 of soil treatment for the T1 and 0.021 g. kg-1 of soil treatment for the T3. The highest content of P2O5 has been registered by the T3 treatment that 0.44 g kg-1 soil with respect to the control (T0), which shows a content of 0.36 g.kg-1 soil. The soil was initially characterized by a potassium content of 0.8 g kg-1 soil, K2O exchangeable rate varied between 0.63 g.Kg-1 and 0.71 g.kg-1 soil respectively T2 and T1.

Keywords: compost, organic amendement, Ntot, P2O5, K2O

Procedia PDF Downloads 590

Authors: Eng. M. Ahmed, A. Ibrahim, M. Ashour

Abstract:

One of the major concerns facing dam is the repair of their structures to prevent the seepage under them. In previous years, many existing dams have been treated by grouting, but with varying degrees of success. One of the major reasons for this erratic performance is the unsuitable selection of the grouting materials to reduce the seepage. Grouting is an effective way to improve the engineering properties of the soil and strengthen of the permeability of the soil to reduce the seepage. The purpose of this paper is to focus on the efficiency of current available grouting materials and techniques from construction, environmental and economical point of view. The seepage reduction usually accomplished by either chemical grouting or cementious grouting using ultrafine cement. In addition, the study shows a comparison between grouting materials according to their degree of permeability reduction and cost. The application of seepage reduction is based on the permeation grouting using grout curtain installation. The computer program (SEEP/W) is employed to model a dam rested on sandy soil, using grout curtain to reduce seepage quantity and hydraulic gradient by different grouting materials. This study presents a relationship that takes into account the permeability of the soil, grout curtain spacing and a new performance parameter that can be used to predict the best selection of grouting materials for seepage reduction.

Keywords: seepage, sandy soil, grouting, permeability

Procedia PDF Downloads 338

Authors: Tienfuan Kerh, Hsienchang Lu, Rob Saunders

Abstract:

Shoreline erosion problems caused by global warming and sea level rising may result in losing of land areas, so it should be examined regularly to reduce possible negative impacts. Initially in this study, three sets of survey images obtained from the years of 1990, 2001, and 2010, respectively, are digitalized by using graphical software to establish the spatial coordinates of six major beaches around the island of Taiwan. Then, by overlaying the known multi-period images, the change of shoreline can be observed from their distribution of coordinates. In addition, the neural network approximation is used to develop a model for predicting shoreline variation in the years of 2015 and 2020. The comparison results show that there is no significant change of total sandy area for all beaches in the three different periods. However, the prediction results show that two beaches may exhibit an increasing of total sandy areas under a statistical 95% confidence interval. The proposed method adopted in this study may be applicable to other shorelines of interest around the world.

Keywords: digitalized shoreline coordinates, survey image overlaying, neural network approximation, total beach sandy areas

Procedia PDF Downloads 243

Authors: Riffat Sultana, Ahmed Ali Samejo

Abstract:

Desert Locust is a critical pest of crop and non-crop plants throughout the old world including Pakistan. Geographically, this pest invades 31 million km2 in about 60 countries during the gregarious phase which may bring calamity. The present study is carried out in order to conduct field observations on oviposition behavior from Thar Desert, Pakistan. Females preferred loose soil for oviposition rather than packed or hard soil. The depth of egg pods inside the soil was measured up to 8.996±1.40 cm, and duration of egg laying was measured up to 105.9±26.4 min. Besides this, an insightful recognition has been made that the solitary females oviposited predominantly in the vicinity of pearl millet (Pennisetum glaucum) and guar or cluster bean (Cyamopsis tetragonoloba) crops in cultivated fields while in uncultivated land preferred the surroundings of bekar grass (Indigofera caerulea) and snow bush (Aerva javanica). It was also observed that nymphs preferred to feed on these host plants. Furthermore, experimental outcomes indicated that gravid females oviposited on the bottom of perforated plastic cages while, they did not find suitable soil for oviposition.

Keywords: calamity, cultivated fields, desert locust, host plants, oviposition behavior

Procedia PDF Downloads 161