Mohammadreza Rahdari; Hasan Ahmadi; Ali Tavili; Mohammad Jafari; Aliakbar Nazari Samani; mohammad khosroshahi; Shahrooz Sharifi
Volume 26, Issue 1 , June 2019, , Pages 226-240
Abstract
Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway ...
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Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway (178 km). For this reason, hourly wind speed and direction data were analyzed. Annual wind roses showed that West and Northwest winds were predominantly about 40%, 50%, 42% and 57% at the stations of Tehran, Shahriyar, Qom, and Imam Khomeini airport, respectively. The highest amount of sand drift potential was at the Imam Airport station (DP= 574, UDI=0.8) in the west and its lowest value was at Qom station (DP= 109, UDI= 0.47) in the south of the region. The drift potential (DP) for aeolian deposits was generally high (DP >400) in the Garmsar (DP= 481), Salafchegan (DP= 485), Saveh (DP= 552) and Imam Khomini airport (DP=574) climatological stations. DP was relatively moderate (200>DP>400) at the Shariyar and Kahak stations in the northwest and south of study area, respectively; and weak (DP<200) in the Tehran and Qom climatological stations. There was an increasing trend in the transport of sand when moving from Namakzar railway station to the Imam Khomeini railway station. Also field evaluations indicated the sensitivity of the Separ Rostam-Namakzar block to entry of sand, which was 21.3 kilometers long. Finally, it is suggested to railway directors of the Islamic Republic of Iran to proceed with the assessment of sand drift potential near railways station for control of sand deposition.
Ali Akbar Nazari Samani; leila Biabani; Hamidreza Abbasi; Hasan Khosravi
Volume 25, Issue 3 , November 2018, , Pages 594-612
Abstract
Wind, as a major driving factor on soil erosion in arid and semi-arid areas, needs to be investigated precisely to prevent its undesirable effects. The main purpose of this research was to determine the spatial variability of wind erosivity and sand drift around Urmia Lake. For this aim, ...
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Wind, as a major driving factor on soil erosion in arid and semi-arid areas, needs to be investigated precisely to prevent its undesirable effects. The main purpose of this research was to determine the spatial variability of wind erosivity and sand drift around Urmia Lake. For this aim, the anemometry data of eight synoptic stations adjusted to the Lake were analyzed for the whole period time. Annual wind-roses showed that despite the very high spatial and temporal changes of wind variables (speed and direction), major prevailing winds were blown from the East and West, respectively. Also, annual storm-roses depicted that the erosive winds blew mainly from South and Southwest direction. These winds had a unidirectional regime in summer and spring, while in fall and winter, a multi directional regime was observed. The results of calculated sand drift power by Fryberger and Dean Formula indicated a low to moderate class of wind erosion potential and the final direction of sediment transport was mainly to northeast. According to the Letu-Letu equation, sand transport flux is varied between 0.05 to 0.76 Ton/m/year. Although the windiness of study area is moderate, the Tsoar sand mobility index is less than one, indicating inactive sand dunes. However, due to the low vegetation established on the sand dunes surface, it can be drawn that the role of human factors (especially cattle grazing and trampling) as well as the salinity caused by the drying of the Lake are responsible for this situation.