Studying Parameters of Plant Morphology, Morphometric, Mineralogy, and Grading of Wind Deposits of Nebkas in Sarakhs Region

Wind processes include deposit transportation by wind which occurs in different areas such as coastal regions, cold and hot deserts, and agricultural lands. Common feature of all these locations is that the vegetation is sparse and/or there is no vegetation. Aeolian processes lead to the dispersion of clay particles, mud, sand, and grit and create sand hills in different regions. These regions are varied in terms of air quality, soil chemistry and nutrients due to the migration of these hills through strong winds and their invasion to nearby ecosystems. Many studies have been done in recent years on sand particles and their morphology in Iran which have shifted from qualitative to quantitative view over time. The current study attempts to present a quantitative-analytical comparison on granulometry and morphoscopy of sands and plants' morphological indicators with morphometric indicators of Nebkas in Sarakhs region to better specify the nature of them and analyze their creation by finding their similarity and differences. Nebkas, which is studied in this work, extends in western Nebkalands of Sarakhs from northwest to southwest in geographical coordination from 36 28' 41" to 36 37' 59" north and from 61 1' 30" to 61 3' 43" east. These regions are of critical centers of wind erosion in Sarakhs town and dominant wind direction is from west north to east south. Three sites in northern, almost central, and southern parts of Nebkalands were selected after reviewing satellite images and field surveys. First site (Yaztape) is located in the most northern point of the region where most Nebkas have alhagi plants. Second site (Tam Rasoul) is located in the furthermost southern part of site 1 and dominant plant of these Nabkas is wild rue. Third site (Samad Abad) is located in the southern part of study area and dominant plant of this Nebka is stipagrostis plumose. To study the samples of Nebkas' wind deposits, two transects in Yaztape area (northern part of Nabkaland), two transects In Tam Rasoul (central parts of the area), and two transects in Samad Abad (southern part of the area) were obtained. The length of each transect was 100 meters and the locations of transects were selected randomly. To study the indicators of plant morphology and morphometric indicators of Nebka and also to investigate the relations between them along each transects, parameters such as height, length, and volume of Nebka and height, leaf diameter, volume and the environment of the plant and also samples of wind deposits of each Nebka were used. Five samples were selected from deposit samples of each three study area along wind blast through Nebka random selection to perform pH tests, EC, texture, mineralogy, and grading operations. Mineralogy of deposits from each three sites was determined using XRD test. Hydrometric method was used to determine deposit texture. Wet sieve was used to determine deposit grading indicators and more common formulas were applied to specify mean, skewness, stretch, and standard deviation and Folk's classification. Correlation coefficient was calculated to investigate the effect of plant morphology indicators on morphometric indicators of Nebka more accurately. Mineralogy tests (XRD)
Based on results of mineralogy tests, it can be observed that minerals of all three sites are almost similar and generally have deposit origin.
Deposit texture test
Removal area of deposits is not far from sedimentation area as the portion of sand is very high in deposits and also all deposit samples are placed in sand texture class.
pH determination and EC tests
Electrical conductivity of deposits is very low and this low electrical conductivity is decreased from site 1 (Yzatape) towards site 3 (Samad Abad) while the distance of deposit transportation is increased. Analysis of deposits' pH based on deposit transportation distance shows that pH of wind deposits increases with deposit transportation distance.
Correlation of plant morphology indicators with Nebka morphometric indicators
Highest correlation coefficient is between plant volume indicators and Nebka's volume. Generally, large diameter of Nebka creates the highest correlation with Nebka's morphometric indicators and environment and plant volume indicators come after that. This study shows that the indicator of plant height among plant morphology has the lowest effect on Nebka's morphometric indicators. Analysis of explanation coefficient of studied indicators shows that the strongest explanatory relation among studied indicators is between plant volume and Nebka volume.
Studying plant morphology and Nebka morphometric parameters
Studies done show that the most important factor affecting Nebka morphometric indicators is not deposit transportation distance but the most important indicator of plant morphology is studied and the effective factor of this research is plant volume.
Grading tests
Plant volume indicator is more effective in changes of Nebka's deposit diameter than the indicator of deposit transportation distance. Also, it can be said that deposit transportation distance is between 20 and 50 Km as D50 of all samples and the average diameter of most deposit grins is in the class of very fine sand. Considering the results of mineralogy tests, deposit texture determination, evidences of locals, and dominant wind direction, it can be argued that these regions have similar origin. It can be said that the origin of Nebkas' deposits is probably the southern regions of Turkmenistan near Iran's border as the origin of most minerals, their salts, and the grading of studied sample is sedimentary. Statistical analysis shows that indicators of plant's large diameter, plant environment and volume, and finally plant height among studied plant morphology indicators have the highest correlation coefficient with morphometric indicator of Nebkas. In other words, in a certain vegetative form which the height variations of plant is low, the indicator of plant height has less effect on morphometric indicators of Nebkas than other plant morphologic indicators. The most effective factor on Nebka's volume among studied plant morphology indicators is plant volume. Analysis of Nebka's height trend shows that this morphometric indicator of Nebka decreases gradually in the direction of wind so that the ability of wind regime to carry deposit reduces by increasing the distance. After investigating results of grading tests for indicators of D10, D50, and D90, and average diameter of particles, it can be said that plant volume have larger effect on the value of these indicators compared with distance from removal area. Results of deposit grading tests in these three sites showed that particles' homogeneity is very well. When skewness is considered, it can be said the further the distance of deposit carrying is, the more the value of skewness is increased and skewness is directed towards fine-grained particles. However, the effect of deposit carrying distance is less than plant volume created Nebkas. Another study done on the extension of deposit showed that as it was expected, the extension of deposits is reduced by increasing deposit carrying distance and in this case, the effect of deposit carrying distance is more than the volume of plants created Nebkas.