چکیده:
Aeolian process and subsequently soil erosion are key factors in dryland environments. Such phenomena are related not only to geoecological factors (lithology, topography, and climatology) but also to land-use and plant cover changes. Formation of new sand dunes in Damghan explains the development of human activities over the past. The aim of this study is to explain the land use changes and their contributions and impacts on Aeolian sediments in Damghan Region. The study was carried out using topographic and geologic maps, satellite imagery, aerial photographs, meteorological data, field observation and samplings. According to meteorological data, period of strong winds (May to Jun) were identified. This period is wind activity period. So, based on this period, unprotected soil surface by crop residues with the interpretation of satellite images was determined. The field samples were carried out from May to June 2008 when the wind was active. The study methods include sieving soil granulometry, and analyzing the particle size. Granulometric analyses were performed using conventional dry sieve method. The results of statistical analysis of grain size distribution showed that the mean and median of particle size were composed of coarse and very coarse sand particles. The study indicated that 90% of the agricultural lands contained more than 23% soil aggregates, where in areas with sensitive particles to erosion the Figure was 35%. It can be argued that agricultural land in study area are resistant to wind erosion.
خلاصه ماشینی:
"A study on the wind erosion potential of agricultural lands after crop harvesting (Case study: Damghan Region) N.
The study indicated that 90% of the agricultural lands contained more than 23% soil aggregates, where in areas with sensitive particles to erosion the Figure was 35%.
-Soil sampling To assess the influence of soil physical properties on wind erosion, the granulometry survey was carried out in the selected agricultural lands.
Soil sampling was carried out based upon three principles; a: dry period in area b: season with strong winds and c: soil without covering vegetation or crop residues.
-Determination of sensitive and resistant areas to erosion based on grain size (potential of the sedimentation) Dynamic and physical analysis of grain movement by wind showed that particles with different diameters had experienced different forms of transport, and each of the forms of transportation complied with wind specified speeds (Lancaster 2009).
Resistant areas to wind erosion based on resistant particles (View the image of this page) -Relationship between the amounts of soil aggregates and soil erodibility Figure 7 shows the relationship between the amounts of soil aggregates and soil erodibility, which is a logarithmic relationship.
The research indicated that, in study region, the average particle size of the all soil samples are coarse sand (895.
Generally, according to the favorable condition of climate factors for erosion in area, the impact of wind erosion in agricultural land depends on vegetation and surface soil properties.
The impact of agricultural periodic activities on wind erosion (Case study: Damghan area)."