East Azarbaijan Agricultural and Natural Resources Research and Education Center, Agricultural Research Education and Extension Organization (AREEO), Tabriz, Iran , j.yarahmadi@areeo.ac.ir
Abstract: (121 Views)
1- Introduction
Dunes are one of the most important and sensitive landforms sensitive to wind erosion. Their activity level varies depending on the intensity of various climatic and terrestrial factors. Dust caused by wind erosion in the area of dunes is one of the most important dangers and serious challenges in arid and semi-arid regions of the world, which has been aggravated by climate changes in recent years. Due to the location of IRAN in the dry and semi-arid belt, it has been exposed to numerous local and extra-local dust systems. Dust storms have been a serious crisis in the country's provinces for the past few years and have brought dangerous consequences for the residents of these provinces in terms of environment, health, and economy. The prolonged recent droughts in East Azerbaijan and the drying up of Lake Uremia have made the threat of sand and salt storms in the coastal areas of Lake Uremia possible. The purpose of this research was to introduce the dunes in the Uremia Lake basin in East Azerbaijan province, where the mobility of dunes was determined using the Lancaster index, and the level of their future activity was predicted by carrying out a sensitivity analysis.
2- Methodology
The dunes in the Lake Uremia basin in East Azarbaijan province were identified through the literature review and field visits, and then, using Google Earth images, their area was verified and then their spatial distribution map was prepared in the ArcGIS software environment. In the present project, the sand dunes of Shush Qom located in the village of Maqsoodlou and Gildir in the political area of Harris County are reported for the first time. Here, the mobility of sand dunes in the study area is calculated based on the Lancaster index. To calculate this index, meteorological data from the last 30 years of synoptic weather stations near the studied sand dunes have been used. Blaney Kridel method was used to calculate the annual potential evapotranspiration, and its calculations were done in the R program environment separately for each meteorological station. Also, the frequency of winds with a speed higher than the erosion threshold speed (6 m/s) at a height of 10 meters from the ground is considered. After calculating the amount of sand dunes mobility, the sensitivity analysis method has been used to reveal the possible effects of climatic change elements on the mobility of sand dunes.
3- Results
The results showed that the sand dunes of Qom Tepeh, located on the edge of Lake Urmia and west of Tabriz metropolis, were active in 81% of the last 30 years, and in other words, they were not active in only 19% of the statistical period. Also, the results of the Lancaster index indicate the intensification of the mobility of the sands in the Qom Tepeh dunes in recent years. This fact can be justified in the form of the prolonged of droughts and the expansion of the dry areas of the Uremia lake bed; Also, field observations indicate the instability of the surface of these dunes due to the indiscriminate extraction of sand from these hills for use in the sand brick production plant and other agricultural and industrial uses. The dominant wind direction of Shush Qom region is south-southwest and winds with intensity greater than (>6m/sec) constitute about 12% of all observed winds at the Harris synoptic station. Based on the results of the Lancaster index, the dunes of the Shush Qom region have been active in half of the studied period; Of course, the short statistical period of the Harris station (last 12 years) has prevented a detailed analysis of the past behavior of this sandy area. In both study sites, the activity of the sands was mainly limited to the top of the dunes. Despite observing a direct relationship between the Lancaster index with the frequency of winds above the threshold of erosion and evapotranspiration and an inverse relationship with precipitation, the sensitivity of the Lancaster index to the decreasing or increasing changes of climate variables is not the same in the mentioned sites.
4- Discussion & Conclusions
Sand dunes are one of the famous geomorphological forms in arid and semi-arid regions of the world, and their activity has intensified with climate changes in recent years. Therefore, investigating and monitoring the behavior of this phenomenon in terms of its impact on the emergence and escalation of the dust phenomenon is an undeniable necessity to reduce the effects of environmental crises. Even though today the Lancaster index is widely used in discussions related to the monitoring of sand dune activity in different weather conditions around the world, it is necessary to mention the lack of proper spatial distribution of weather stations and the short period of statistical observation. Also, the use of data from meteorological stations that are located further away from the sandy areas, makes the accuracy and correctness of the calculations of the Lancaster index doubtful, and the results should be evaluated with field observations and other valid scientific documents. On the other hand, in addition to analyzing the sensitivity of the Lancaster index, it is necessary to use the results of different climate change scenarios and appropriate downscaling methods in revealing the climate data changes affecting the Lancaster index in predicting the future behavior of sand dunes.
Dunes are one of the most important and sensitive landforms sensitive to wind erosion. Their activity level varies depending on the intensity of various climatic and terrestrial factors. Dust caused by wind erosion in the area of dunes is one of the most important dangers and serious challenges in arid and semi-arid regions of the world, which has been aggravated by climate changes in recent years. Due to the location of IRAN in the dry and semi-arid belt, it has been exposed to numerous local and extra-local dust systems. Dust storms have been a serious crisis in the country's provinces for the past few years and have brought dangerous consequences for the residents of these provinces in terms of environment, health, and economy. The prolonged recent droughts in East Azerbaijan and the drying up of Lake Uremia have made the threat of sand and salt storms in the coastal areas of Lake Uremia possible. The purpose of this research was to introduce the dunes in the Uremia Lake basin in East Azerbaijan province, where the mobility of dunes was determined using the Lancaster index, and the level of their future activity was predicted by carrying out a sensitivity analysis.
2- Methodology
The dunes in the Lake Uremia basin in East Azarbaijan province were identified through the literature review and field visits, and then, using Google Earth images, their area was verified and then their spatial distribution map was prepared in the ArcGIS software environment. In the present project, the sand dunes of Shush Qom located in the village of Maqsoodlou and Gildir in the political area of Harris County are reported for the first time. Here, the mobility of sand dunes in the study area is calculated based on the Lancaster index. To calculate this index, meteorological data from the last 30 years of synoptic weather stations near the studied sand dunes have been used. Blaney Kridel method was used to calculate the annual potential evapotranspiration, and its calculations were done in the R program environment separately for each meteorological station. Also, the frequency of winds with a speed higher than the erosion threshold speed (6 m/s) at a height of 10 meters from the ground is considered. After calculating the amount of sand dunes mobility, the sensitivity analysis method has been used to reveal the possible effects of climatic change elements on the mobility of sand dunes.
3- Results
The results showed that the sand dunes of Qom Tepeh, located on the edge of Lake Urmia and west of Tabriz metropolis, were active in 81% of the last 30 years, and in other words, they were not active in only 19% of the statistical period. Also, the results of the Lancaster index indicate the intensification of the mobility of the sands in the Qom Tepeh dunes in recent years. This fact can be justified in the form of the prolonged of droughts and the expansion of the dry areas of the Uremia lake bed; Also, field observations indicate the instability of the surface of these dunes due to the indiscriminate extraction of sand from these hills for use in the sand brick production plant and other agricultural and industrial uses. The dominant wind direction of Shush Qom region is south-southwest and winds with intensity greater than (>6m/sec) constitute about 12% of all observed winds at the Harris synoptic station. Based on the results of the Lancaster index, the dunes of the Shush Qom region have been active in half of the studied period; Of course, the short statistical period of the Harris station (last 12 years) has prevented a detailed analysis of the past behavior of this sandy area. In both study sites, the activity of the sands was mainly limited to the top of the dunes. Despite observing a direct relationship between the Lancaster index with the frequency of winds above the threshold of erosion and evapotranspiration and an inverse relationship with precipitation, the sensitivity of the Lancaster index to the decreasing or increasing changes of climate variables is not the same in the mentioned sites.
4- Discussion & Conclusions
Sand dunes are one of the famous geomorphological forms in arid and semi-arid regions of the world, and their activity has intensified with climate changes in recent years. Therefore, investigating and monitoring the behavior of this phenomenon in terms of its impact on the emergence and escalation of the dust phenomenon is an undeniable necessity to reduce the effects of environmental crises. Even though today the Lancaster index is widely used in discussions related to the monitoring of sand dune activity in different weather conditions around the world, it is necessary to mention the lack of proper spatial distribution of weather stations and the short period of statistical observation. Also, the use of data from meteorological stations that are located further away from the sandy areas, makes the accuracy and correctness of the calculations of the Lancaster index doubtful, and the results should be evaluated with field observations and other valid scientific documents. On the other hand, in addition to analyzing the sensitivity of the Lancaster index, it is necessary to use the results of different climate change scenarios and appropriate downscaling methods in revealing the climate data changes affecting the Lancaster index in predicting the future behavior of sand dunes.
Received: 2023/11/29
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