Soil science
H. Emami; M. Memarzadeh
Abstract
Introduction
Wind Erosion is the natural process of transportation and deposition of soil by wind. It is a common phenomenon occurred mostly in dry, sandy soils or anywhere the soil is loose, dry, and finely granulated. Heavy metals are found in the environment and soils may become contaminated by accumulation ...
Read More
Introduction
Wind Erosion is the natural process of transportation and deposition of soil by wind. It is a common phenomenon occurred mostly in dry, sandy soils or anywhere the soil is loose, dry, and finely granulated. Heavy metals are found in the environment and soils may become contaminated by accumulation of heavy metals through emissions from the rapidly expanding industrial areas, mine tailings, disposal of high metal wastes, leaded gasoline and paints, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater irrigation, coal combustion residues, spillage of petrochemicals, and atmospheric deposition. Soils are the major sink for heavy metals released into the environment by the aforementioned anthropogenic activities and their total concentration in soils persists for a long time after their introduction. The heavy metal contamination of soil and its potential risks to humans and the ecosystem is a significant concern. Windy deposition, which is the process of heavy metals being transported by erosive winds and deposited onto soil, is one of the sources of heavy metal contamination. Due to the geographical situation and climatic conditions such as arid soil, erosive winds are blown in periods of year in Tabas. Since wind are erosion is severe in this area, huge amounts of wind deposition accompanied with erosive winds entered into this town. Heavy metals through the windy deposition are suspended, translated and finally deposited in residential regions, which can create some problems for human health. Therefore, the knowledge of wind erosion and the human risk of these deposits is essential. The aim of this research was to determine the rate of wind erosion and the concentration of some heavy metals in these deposits.
Materials and Methods
For this purpose, the rate of suspended load was measured monthly from February 2021 to January 2022. Based on previous information from the erosive winds and storms, suspended depositions were gathered in some directions (north, northwest, northeast, west and southwest) of the Tabas entrance. In addition, the suspended load in the city center of Tabas was also measured. The cumulative load of suspended depositions was measured monthly and the concentration of some heavy metals such as manganese (Mn), iron (Fe), cupper (Cu), and zinc (Zn) were measured in these suspended particles. Soil digestion was made by Aqua regia (nitric acid and chloridric acid; ratio of 3:1), and after then atomic absorption was used to measure the total concentration of above heavy metals.
Results and Discussion
The results indicate that Tabas experiences significant wind deposition of suspended loads, with the highest rates entering from the northeast direction and the lowest rates from the southwest direction. This pattern aligns with the wind rose of Tabas, which illustrates the prevailing wind directions in the region. Additionally, substantial suspended loads are observed in the northwest and north directions. The variations in suspended load discharge reveal that the maximum discharge occurs in the city center of Tabas during the months of June and July 2021. This corresponds to the arid climate conditions of these months, where plant growth is limited, soil cohesion is low, and loose soil particles on the surface are susceptible to wind forces. As a result, these loose particles are easily detached by the wind, contributing to the high levels of suspended load. Regarding the spatial variation of heavy metals in suspended particles, the cumulative concentrations of Mn, Fe, Cu, and Zn are found to be higher in the west, northwest, north, and west directions, respectively. This suggests that these heavy metals are transported and deposited in specific areas within Tabas due to the prevailing wind patterns. In terms of temporal variation, the highest concentrations of Mn and Fe in suspended particles are observed in April 2021, predominantly in the northeast and west directions, respectively. On the other hand, the highest concentrations of Cu and Zn are found in May 2021, with the southwest and northeast directions being the primary deposition areas for each metal, respectively. These findings highlight the spatial and temporal dynamics of suspended load and heavy metal deposition in Tabas, emphasizing the influence of wind patterns and climatic conditions on these processes. Understanding these variations is crucial for assessing the potential risks associated with heavy metal contamination and implementing appropriate mitigation measures in the region.
Conclusion
The results of this research showed that most contents of the suspended load are entered from the northeast direction into Tabas. In addition, the spatial variation of heavy metals indicated that the concentrations of studied heavy metals (Mn, Fe, Cu, and Zn) in suspended particles, especially in the western, northwestern, and northern in spring, are very high and they can cause carcinogenic effects on human life. Therefore, the management practices should be mostly made in these directions to control or reduce soil erosion and reduce its damage effects.
Soil science
Fatemeh Nooralivand; A. Farrokhian Firouzi
Abstract
Introduction Wind erosion is one of the important processes of soil degradation in arid and semi-arid regions. Increased soil surface resistance is a key factor to prevent wind erosion. Mulch can increase the resistance of soil surface against erosive agents by creating a coating on the soil surface. ...
Read More
Introduction Wind erosion is one of the important processes of soil degradation in arid and semi-arid regions. Increased soil surface resistance is a key factor to prevent wind erosion. Mulch can increase the resistance of soil surface against erosive agents by creating a coating on the soil surface. The effectiveness of mulch on wind erosion control is on the quantity, type, and durability of the used in dust sources of Iran for stabilizing soil surface against wind erosion. In recent decades, petroleum mulch has been broadly used for stabilizing soil surface against wind erosion in dust sources of Iran. Bio-polymers (e.g. cellulose hydrogel and biochar) and naturally accessible materials (e.g. nanoclay) as environment-friendly mulches can be an alternative to chemical polymers and petroleum mulches. In arid and semi-arid regions, wetting-drying cycles play a crucial role in soil aggregate formation and strength. However, there have been limited studies assessing the impact of wetting-drying cycles on the durability of applied mulches. The main objective of this study was to assess the effectiveness of different types of mulches, including inorganic montmorillonite nanoclay, chemical polyvinyl acetate polymer, and biological biochar and cellulose hydrogel, at various time intervals. The study aimed to improve the physical and mechanical properties of soil, as well as control wind erosion in a loamy sand soil using a wind tunnel. Additionally, the durability of these mulches was evaluated over time after subjecting them to four wetting-drying cycles.Materials and Methods A factorial experiment was conducted based on completely randomized design with three replications. The factors including mulch type (four levels: nanoclay montmorillonite, polyvinyl acetate polymer, biochar and cellulose hydrogel), mulch concentration (Nanoclay montmorillonite: 0, 16 and 32, Polyvinyl Acetate polymer: 0, 8, and 16, biochar and cellulose hydrogel: 0, 65 and 200 g/m2) and duration (21, 42, 63 and 126 days). The soil used in the wind tunnel experiments was collected from a dust source in the southeast of Ahvaz (Site Number 4). Trays measuring 50×30×5 cm were filled with this soil. The soil surface was then uniformly sprayed with an emulsion of Nanoclay and Polyvinyl Acetate. Additionally, biochar and cellulose hydrogel were mixed uniformly with the soil. Water was sprayed on the soil surface to maintain a constant moisture content of 75% of field capacity. After a specified period, soil properties such as mean weight diameter of aggregates, fractal dimension, penetration resistance, and shear strength were measured. The trays were then placed in a wind tunnel, and a wind erosion test was conducted at a wind speed of 20 m/s for a duration of 5 minutes. The amount of soil loss was measured using the weight method. Then, at each time, the best treatment from each mulch (in terms of reducing wind erosion) was selected and subjected to wet and dry cycles (four cycles).Results and Discussion The results showed a significant interaction effects (p<0.01) of mulch type, mulch concentration and time factors on soil aggregate stability and fractal dimension, penetration resistance, shear strength were significant (p<0.01). Soil loss decreased in soils amended with biochar and cellulose hydrogel and increased in the case of montmorillonite and polyvinyl acetate polymer over the time. The amount of soil loss in soil amended with cellulose hydrogel decreased by 99.3%. The highest amount of soil penetration resistance and shear strength was observed in cellulose hydrogel mulch at the fourth time which were equal to 1038 and 123 kPa, respectively. Over time, the mean weight diameter of aggregates increased in the soil treated with cellulose and biochar hydrogels, but decreased in the polyvinyl acetate and montmorillonite nanoclay treatments. There was a negative correlation between aggregate stability and the fractal dimension of aggregates. In terms of soil loss, at the fourth measurement time, soils modified with cellulose hydrogels, biochar, polyvinyl acetate, and montmorillonite nanoclay experienced reductions of 99%, 71%, 84%, and 85% respectively, compared to the control. After four wet and dry cycles, the soil loss further decreased by 98%, 64%, 76%, and 81% in the respective treatments, compared to the control.Conclusion In general, it can be concluded that cellulose hydrogel presented the greatest effect on reducing soil loss and controlling wind erosion. In the soils amended with biochar and cellulose hydrogel, the effect of mulches on reducing soil loss increased over the time. However, the opposite results were found in the case of polyvinyl acetate and montmorillonite nanoclay polymers. Therefore, biochar and cellulose hydrogel in the long term and polyvinyl acetate polymer and montmorillonite nanoclay in the short term can control wind erosion. Wet and dry cycles at all durations increased soil loss. But their effect remained on soil loss reduction until the end of the fourth cycle. The results revealed that environmentally friendly biopolymers synthesized from biomass components can be considered as sustainable sources to reduce wind erosion. Bio-polymers are a new window into the use of sustainable biomaterials instead of synthetics in wind erosion control.
M. Moeinfar; M.H. Rasouli Sadaghiani; M. Barin; F. Asadzadeh
Abstract
Introduction: Dust is one of the most important destructive phenomena in the world, that annually causing damage to human health and the environment. This issue ranks after two major challenges of climate change and water scarcity as the third most important challenge facing the world in the ...
Read More
Introduction: Dust is one of the most important destructive phenomena in the world, that annually causing damage to human health and the environment. This issue ranks after two major challenges of climate change and water scarcity as the third most important challenge facing the world in the 21st century that is considered. Microbial-induced calcite precipitation (MICP) is a relatively green and sustainable soil improvement technique. It utilizes biochemical process that exists naturally in soil to improve engineering properties of soils. The calcite precipitation process is uplifted by the mean of injecting higher concentration of urease positive bacteria and reagents into the soil. In this process, the enzyme present in the bacteria hydrolyzes the urea in the environment and through reacting with the calcium ion, leads in the deposition of calcium carbonate. The main objective of this study is isolation native ureolytic bacteria from different soil of around Urmia Lake and then, the evaluation their efficiency in the MICP for stabilization of sandy soils and reduce windy erosion.
Materials and Methods: In order to isolate ureolytic bacteria, 25 soil samples were taken from different land use in West Azarbaijan province, Iran. To increase the number of ureolytic bacteria in soil samples were used from the enrichment solution and then ureolytic bacteria were isolated and purified. These isolates were subjected to various biochemical tests, as well as the growth curve and urease activity were determined. In order to investigate the potential for soil improvement, a factorial experiment was conducted based on a completely randomized design with two factors including microbial treatment in eight levels (including five isolated bacteria (U3, U8, U16, U35 and U40) and Bacillus pasteurii (as control Positive), non-bacterial and non-cementation (as control negative) and non-microbial but with cementation solution treatments) and another factor including different concentrations of calcium chloride solution with urea at three levels (0.1, 0.5 and 1 molar), in three replications. After injection of cementation solution and bacterial solution to soil, penetration resistance and windy erosion rates in sandy soil were assessed
Results and Discussion: In study, overall 45 isolates of the bacteria were isolated and purified. Among of 44 isolates, five bacterial isolates (U3, U8, U16, U35 and U40) had the highest urease activity. The growth curve of bacterial isolates showed that the highest urease activity and microbial population were in the time period of 13 to 16 hours after microbial culture, which it is represents the best time use bacterial solution in the MICP process. According to the results of soil improvement tests, the amount of soil erosion in the MICP treatment at a wind speed of 25 m/s was zero and the rate of penetration resistance was averaged over 13 MPa, which has a very impressive impact on MICP in controlling wind erosion, especially at high speeds of wind. The results showed that U3 and U16 isolates had the highest amount of urea hydrolysis and also U16 and U3 had the lowest and the highest tolerance to salinity, respectively. The results of the wind tunnel showed that the wind erosion threshold in negative control samples (non-bacterial and non-cementation) were 9.4 m/s and for MICP samples (including five isolated bacteria and Bacillus pasteurii ) were much higher than the wind tunnel speed in the wind tunnel machine in Urmia university (25 m/s). The maximum penetration resistance (13.5 MPa) was obtained in the sample treated with U3 isolate and 1 molar calcium chloride, but negative control treatments (non-bacterial and non-cementation) as well non-microbial but with cementation solution treatments were 0 and 97.0 MPa, respectively.
Conclusion: The amount of soil wind erosion was zero in MICP treatment with the wind tunnel speed 25 m/s that indicates very important effects MICP to control wind erosion of sandy soils to compare control treatments (non-bacterial and non-cementation and non-microbial but with cementation solution) in high wind speeds. The application of MICP treatment in the soil, in addition to increasing its wind erosion resistance, also increased penetration resistance in the soil. Increasing the penetration resistance of MICP treatments (including five isolated and Bacillus pasteurii) can be due to the activity of bacterial isolates, chemical interactions, and the formation of calcium carbonate precipitation into soil cavities, which causes to form a hard layer in soil. Also, obtained resistance by using isolated bacteria indicates that there are many unknown microorganisms that can carry out MICP better than Bacillus pasteurii and probably they will be better compatible and establish because they are native.
Samira Zamani; Majid Mahmoodabadi; Najme Yazdanpanah; Mohammad Hady Farpoor
Abstract
Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion ...
Read More
Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion dominates large parts of the country due to the climate and land mismanagement. In this regard, Kerman as the largest province in Iran has been under influence of erosive winds with high damaging potential. Wind erosion is a function of two agents including erosivity and erodibility. As wind velocity increases, the rate of wind erosion increases as well, while an increase in threshold friction velocity results in sand drift potential reduction. On the other hand, soil properties can control wind erosion rate through affecting both soil erodibility and threshold velocity. In addition, wind erosion is directly influenced by the direction and velocity of wind. Therefore, for better understanding of this phenomenon, analysis of wind erosivity based on meteorological data is of importance. The aim of this study was to analysis wind erosivity in Kerman province and the wind erosion potential in different parts of the province.
Materials and Methods: This study was conducted to investigate the potential of wind erosion in different parts of Kerman province based on seasonal wind data obtained for the period from 2006 to 2010. For this purpose, eight synoptic stations were selected and wind rose and sand rose were plotted for each station using WR Plot View.8 and Sand Rose Graph 3. For each season and for the whole period, erosive wind speed classes, prevailing wind direction, and the sand rose components including drift potential, sediment load and uni-directional index were obtained for each station.
Results and Discussion: This study results indicated that the intermediate wind speed class i.e. 7.7 to 9.8 m s-1 with the west and southwest directions had the highest frequency at most stations. The most erosive winds occurred during winter and summer, while the lowest ones were found in autumn. In winter, the highest wind speed class i.e. >13 m s-1 was the most frequent class. However, precipitations mostly occurring during winter can moderate the sand transport potential, since the higher precipitation causes a higher soil moisture level and enhanced threshold velocity. In addition, Jiroft station had the most frequent calm winds, whereas Lalehzar station exhibited the least frequency of these winds as this site is located in a mountainous region. Among the stations, the highest potential of sand transport (1637 vector unit) and the greatest sediment discharge (102.62 kg m-1 s-1) were observed at Rafsanjan station. However, the lowest sediment discharge was found at Jiroft station with 22.40 kg m-1 s-1. In all stations, the values of DPt were more than 400 indicating high wind erosion potentials in most areas of the province. The assessment of the uni-directional index illustrated that the investigated wind properties varied for different seasons and regions. Analysis of this index showed that Zarand and Jiroft had multi-directional winds, while other stations with a uni-directional index ranging from 0.3 to 0.8 experienced bi-directional winds with moderate variations. Furthermore, the analysis of resultant drift direction implied that the sand transport direction in Kerman, Jiroft, Sirjan, Rafsanjan and Shahrbabak sites was from west to east, at Lalehzar station was from southwest to northeast, at Bam station was from north to south, and at Zarand station was from northwest to southeast. The highest values of total drift potential in Bam, Jiroft and Zarand were obtained in summer season, while the maximum total drift potential was recorded in wintertime for Kerman, Rafsanjan, Shahrbabak, Sirjan and Lalehzar locations. The findings of this study revealed the significance of wind erosivity analysis in order to make a better understanding of wind erosion processes and achieve a more suitable strategy to combat this environmental threat.
Conclusions: It was concluded that due to climate conditions, Kerman province as the largest province of Iran has experienced high potentials of wind erosion and sand transport. In addition, the prevailing direction and most frequent velocity classes of winds differ among different parts of the province demonstrating the possibility of the formation of different features of wind erosion. Finally, the high values of DPt (> 400) were obtained for most stations, showed a high wind erosion potential in the province.
T. Jamili; B. Khalilimoghadam; E. Shahbazi
Abstract
Introduction: Wind erosion is one of the most serious problems in southwest Iran. Fine-grained structure of sand dunes with not enough strong composition and their low moisture retention property make them susceptible to wind erosion. They lack organic matter and are considered inherently of low fertility ...
Read More
Introduction: Wind erosion is one of the most serious problems in southwest Iran. Fine-grained structure of sand dunes with not enough strong composition and their low moisture retention property make them susceptible to wind erosion. They lack organic matter and are considered inherently of low fertility (Ahmadi, 2002). Studies have shown that non-erodible materials which include bentonite clay (Diouf et al., 1990), ureamelamine formaldehyde and urea–formaldehyde with 0.25% sodium chloride (Lahalih and Ahmed, 1998), acids, enzymes, lignosulfonates, polymers, tree resins (Santoni et al., 2001), waterborne polymer emulsion (Al-Khanbashi and Abdalla, 2006), polyvinyl alcohol and a polyvinyl acetate emulsion (Newman et al., 2005; Han et al., 2007), ash and polyacrylamide (Yang and Zejun, 2012).have significant potential in reducing wind erosion The area under farming of sugarcane in Khuzestan, Iran, is more than 130,000, ha. Vinasse and Filter Kike are two organic ingredients of sugarcane residues which are generated as byproduct materials insugarcane processing. In recent years these residues have been released into the environment and cause it regarded as water pollutant. Over 800,000 m3 of Vinasse is annually stored in each agro-industry. Vinasse also is rich in K, Ca, and Mg with moderate amounts of P and N,and non toxic complexes or heavy metals. Filter Kike is another residue produced in huge amounts by the agro-industry that is composed of cellulosic substances, CaCO3, N, P, K, organic matter, and clay. Therefore, the objective of this research is to investigate the effect of sugarcane mulch on water holding capacity in soil. This study is performed to evaluate the feasibility of using sugarcane residues inproduce of ecofriendly mulches for environmental use. In order of achieving these goals, Vinase, Filter Cake, and clay soil from near the sand dunes were used as sugarcane mulches. Further comparison between traditional oil mulches and sugarcane mulches was also carried out.
Materials and Methods: The experiments were conducted in the soil laboratory of Khuzestan-Ramin University of Agricultural and Natural Resources. For this purpose, Vinasse and clay soil samples were used to make sugarcane mulches. Different quantities of Vinase, Filter Kike, and clay samples were mixed in water to select the best batch mix (by trial and error). A mulch sprayer was then used to spray the batch mixes on sand dune beds packed in trays 1054510cm. In addition, the same procedures were employed to choose an oil mulch treatment as control for comparison with sugarcane mulch treatments. Water holding capacity was measured in 100, 333, 1000, 5000, 10000, 15000 hPa suction by pressure plate and Macro elements ( N, P, K ) and microelements (Fe, Cu, Zn) were determined by conventional methods and atomic absorption in each treatment. Experiments were carried out using a factorial experiment with a completely random design in threereplicants.
Results and Discussion: The wide range of pH values obtained were dependent on the different batch mixes of Vinase, clay soil, and Filter Kike. Reaction (pH) of Vinase was lower (5.00) than those of Filter Kike (7.5) and soil (8.07). EC and SAR values of treatments were both affected by Vinase, soil, and Filter Kike. This could be due to the higher EC and the low level of SAR in Vinase in contrast to soil and Filter Kike. EC and SAR are two major chemical factors known to affect sand dune stabilization (Bresler, 1982). Based on Table 3, N, P, K, Fe, Zn, and Cu in sugarcane mulches varied from 0.15-0.66 (%), 10.82-28.46 (mg.Kg-1), 133.01-633.33 (meq.Li-1), 15.22-36.76 (mg.Kg-1), 2.19-2.93 (mg.Kg-1), and 0.92-4.1 (mg.Kg-1), respectively. The results revealed that sugarcane mulches are rich in N, P, and K that are essential in soil fertility.
The results determined that there was significant effect (p
S. Poormand; Ahmad Gholamalizadeh Ahangar; A. Dehvari
Abstract
Introduction: Wind erosion is one of the most important factors in desert environments. Prevailing winds can shift sand dunes and affect their accumulation and morphology. Also, wind regime determines the direction of sand dune mobility in different ways. Therefore, the wind regime, frequency, direction ...
Read More
Introduction: Wind erosion is one of the most important factors in desert environments. Prevailing winds can shift sand dunes and affect their accumulation and morphology. Also, wind regime determines the direction of sand dune mobility in different ways. Therefore, the wind regime, frequency, direction and velocity are supposed to be the most important factors to form the morphology of sand dunes. Wind energy and changes in different directions (wind regime) have large impacts on the morphology, maintenance and transformation of wind features. Having a global knowledge of the magnitude of aeolian processes, we can assess the powerful impact of sand dune mobility on residential areas and infrastructures. The most important factors including the frequency, magnitude and directional mobility of aeolian processes have a very important effect on the entrainment and form of sand dunes.
Materials and Methods: To understand and identify the wind erosion regions, wind regime is a useful way since there is a strong correlation between wind regimes and sand dune morphology and structure. Sand rose and wind rose are assumed to be easy, fast and most accurate methods for the identification of wind erosion. Wind regimes processes have been studied by many researchers who believed that investigating wind regimes and sand dune mobility gives a measure of drift potential. Drift potential is a measure of the sand-moving capability by wind; derived from reduction of surface-wind data through a weighting equation. To predict drift potential, wind velocity and direction data from meteorological synoptic stations were used. Regarding the estimation of sand transport rate by wind, many formulas exist such as Bagnold, Kawamura, and Lattau. Also, many software applications have been suggested. However, among these formulas, Fryberger’s is the best and has been widely used since 1979.
Results and Discussion: The aim of this study was to analyze wind velocities and directions from 1992 to 2003 in order to predict the volume of sand transportation and its direction using sand-rose and wind-rose softwares. As described earlier, in this research, the drift potential (DP) is estimated for all possible wind speed categories, summed up for all categories of each direction sector using Fryberger’s Equation. The sand drift potential in Shileh was estimated about 3439 vector units with a resultant drift direction along the Southeast, which places it in the high class of wind erosive power based on the Fryberger and Dean (1979) classification method. The sand drift potential values show that the resultant drift direction is from the Northwest towards the Southeast. It was also found that the most powerful winds (the prevailing winds) blow in the summer and the spring seasons, respectively. In contrast, the percentage of calm winds increases during autumn and winter times. The sand transport discharge was predicted to be 20.422 t m-1 year-1 using Lattau and Lattau Equation. With regard to the monthly sand rose, it was seen that the resultant drift potential was low in December and January and high in June and July. The prevailing wind direction ranged from North to Northwest in all seasons. The winds with the highest velocities were observed in the summer, while the winds with lower velocities were observed during the winter. Wind velocities higher than 11 m s-1 had the largest frequencies in the summer and the lowest frequencies in the winter. Wind unidirectional index (UDI) is estimated to be 0.95, implying that the index provides a suitable condition for the creation of transverse (barchanoid) dunes.
Conclusion: The Sistan plain is one of the windiest places in the world that is exposed to wind erosion and dust storms. The result of this study is very important due to the construction of an international roadway that connects Chabahar port to Sistan plain and continues towards the Afghanistan border. Therefore, the practical result of this research could be used to protect this highway from sand dune migration. The residential areas and the infrastructure can be damaged by the migration of sand dunes since the sand dunes can move both spatially and temporally. For example, we can even notify the highway passengers about the rate of monthly and seasonal migration of sand dunes so that they avoid travelling during high-storm seasons. The results of this study are also important regarding wind-break design to protect the infrastructure such as highways and agricultural fields. Therefore, sand encroachment hazards affect man-made infrastructures due to wind speed and direction. Sand drift potential is a serious hazard to settlements and other lands as well. This problem is accelerated by the extreme arid conditions (such as the case of Shileh) that may occur in different months of summer.
Keywords: Resultant Drift Direction, Sand Drift Potential, Sand Dune, Wind Erosion, Wind Regime
F. Bahreini; A. Pahlavanravi; A. Moghaddamnia; Gh. Rahi
Abstract
Desertification and land degradation in arid, semi-arid and sub-humid dry regions, are a global environmental problem. Therefore, accurate assessment of desertification trend will be useful to prevent and eradicate these problems. The study area is located in Daiyer city of Boushehr province. In this ...
Read More
Desertification and land degradation in arid, semi-arid and sub-humid dry regions, are a global environmental problem. Therefore, accurate assessment of desertification trend will be useful to prevent and eradicate these problems. The study area is located in Daiyer city of Boushehr province. In this study, in order to assess land degradation according to local conditions of the study area, two factors of wind erosion and climate were selected as the main factors affecting desertification. Assessment of desertification status in the study area was conducted on basis of these two factors and weighting indices according to the IMDPA model. After separating work units (Geomorphologic facies), numerical value of each index was determined for each work unit, a data layer for each index was prepared and the layer related to each factor was specified by calculating the geometric mean of its indices score. Then, desertification intensity map was created by combination and determination of geometric mean of factors. The results indicated that 31.74% of the studied area falls within the medium class, 62.62% in the severe class and 4.65% in very severe desertification intensity class. Work units 6 and 8 with maximum quantitative values were placed in first priority of degradation. The work units 9, 13, 12, 10, 14, 15, 2, 7, 4, 3, 1, 11 and 5 with minimum quantitative values had lower priorities, respectively. Among the studied indices, two indices of dryness and non- living cover density percentage were the most important factors causing the desertification in this region.
