Moslem Yazdani; Hamidreza Azimzadeh; Hamidreza Karimzadeh; Mohsen Soleimani
Volume 32, Issue 1 , May 2025, , Pages 18-34
Abstract
Background and ObjectivesAccurate measurement of wind erosion and dust intensity requires precise sediment traps. However, traps with varying geometric and aerodynamic properties differ in their efficiency for collecting, retaining, and selecting wind-blown particles. This study evaluates the collection ...
Read More
Background and ObjectivesAccurate measurement of wind erosion and dust intensity requires precise sediment traps. However, traps with varying geometric and aerodynamic properties differ in their efficiency for collecting, retaining, and selecting wind-blown particles. This study evaluates the collection efficiency, retention capacity, and particle selectivity of two widely used wind erosion sediment traps—the Cox Sand Catcher (CSC) and the Modified Wilson and Cooke (MWAC)—in Iran, where they have recently been implemented for wind erosion monitoring.MethodologyTests were conducted using soils from two wind erosion hotspots in Iran: God-e-Govar (Bafq) and Gavkhuni (Sajzi). A suction-type wind tunnel was equipped with custom-designed bases for the traps and soil trays. Experiments were performed in a controlled laboratory setting at wind speeds of 6.1, 7.88, 9.35, and 10.62 m/s. Collection efficiency, retention capacity, and particle selectivity were measured for both traps.ResultsFor loamy sand soil, the CSC trap’s collection efficiency at wind speeds of 6.1, 7.88, 9.35, and 10.62 m/s was 20.61 ± 1.11%, 43.06 ± 2.47%, 35.90 ± 5.12%, and 29.41 ± 1.78%, respectively. For sandy soil from Bafq, efficiencies were 25.35 ± 3.35%, 47.33 ± 4.00%, 41.68 ± 5.19%, and 33.11 ± 3.83%. In contrast, the MWAC trap’s efficiencies for loamy sand were 29.75 ± 4.02%, 31.95 ± 7.18%, 57.57 ± 5.21%, and 62.84 ± 5.82%, and for sandy soil, 43.92 ± 8.83%, 44.23 ± 4.34%, and 47.19 ± 2.97% at the respective wind speeds. Both traps exhibited retention efficiencies exceeding 95% for both soil textures. Selectivity was lower for very fine particles (<100 µm) and very coarse particles (>1 mm), but the CSC trap showed greater selectivity for sand particles due to its design.ConclusionThe MWAC trap’s collection efficiency increased with wind speed for both loamy sand and sandy soils, whereas the CSC trap’s efficiency peaked at approximately 8 m/s before declining. These differences stem from the traps’ geometric and aerodynamic designs. Both traps showed reduced selectivity for very fine (<100 µm) and very coarse (>1 mm) particles, with the CSC trap being more selective for sand particles. Collection efficiency, retention, and selectivity depend on soil particle size distribution, wind speed, and trap design.
Morteza Akbari; Hamid reza Karim zadeh; Reza Modares; Bahareh Chakoshi
Volume 14, Issue 2 , January 2007, , Pages 124-142
Abstract
Desertification is the ecologic and biologic reduction which may occur naturally or non naturally. Desertification process usually effects arid and semi arid region and reduce the land efficiency very rapidly. This study has been conducted to evaluate and classify desertification with the aim of geographic ...
Read More
Desertification is the ecologic and biologic reduction which may occur naturally or non naturally. Desertification process usually effects arid and semi arid region and reduce the land efficiency very rapidly. This study has been conducted to evaluate and classify desertification with the aim of geographic information system and remote sensing techniques. In this study, TM data of 25 shahriver 1369(16 October 1990) and ETM+ data of 16 shahrivar 1380 (7 October 2001) were used. Geometric, radiometric and sun height angle correction were carried out on the images. Supervised and unsupervised classification were used for both two images and 9 land uses were classified and compare quantitatively due to geomorphology and desertification attributes. Each main and partial desertification factor was input to geographic information database and scaled to make the map of desertification severity based on recommended method for Iran and FAO map of desertification vulnerability. The result of desertification severity which shows desertification condition, velocity and potentiality, showed that natural desertification occurs in 35 % of area with different medium, high and very high desertification severity. Anthropogenic desertification includes 65 % of study area with high and very high condition. But in desertification vulnerability map, very high desertification vulnerability was determined in 20 % of area with simultaneous human and animal effect and high desertification vulnerability was determined on 80 % area with only animal effect. According to the map, for arid region of north of isfahan, it was identified that range land use change to agriculture, improve agricultural patterns, over grazing, incident economic condition and ground water over exploitation are the most important anthropogenic factor, and drought and soil and water salinity are the most important natural factors. Desertification trend is enhancing to north west of the study area which will make trouble for rangelands, residential and industrial areas.