azadeh gohardoust

Numerous studies have individually examined the influence of neighboring countries on dust generation in southwestern Iran (Khuzestan). However, the specific countries and regions within those countries with the most significant impact on dust events in the southwest still need to be clarified. This study aimed to identify the primary sources of dust emissions affecting Khuzestan using the Aerosol Optical Depth (AOD) index for dust detection and the HYSPLIT model for tracing dust pathways.

Dust events in Khuzestan province from 2003 to 2017 were identified using MODIS imagery and a suitable dust detection algorithm. Three criteria were applied to each event: spatial extent exceeding 50% of synoptic stations, horizontal field of view less than 5 km, and detection in at least three consecutive synoptic reports. Considering typical dust ingress into Iran at lower and middle atmospheric layers, dust pathways were investigated at 500, 1000, and 1500 meters above ground level. HYSPLIT model outputs for dust event days were combined with AOD images from each year's day before the event in Khuzestan. Areas with the highest dust emissions towards Khuzestan were identified by analyzing AOD concentrations in the days preceding dust events. Regions exceeding a threshold of 30 times the AOD concentration were designated as dust sources or intensification zones. This analysis was performed for each year and the entire period, allowing for prioritization of the most significant dust source areas.

Our analysis of dust events revealed that different regions dominated dust emissions toward Khuzestan across the study period. In 2003, northern and eastern Arabia contributed the most dust. Subsequent years exhibited varying source regions, including the Iraq-Syria border (2004), Saudi Arabia (2005), southern Iraq (2006), southern and southeastern Iraq (2007-2008), southwestern Iraq and northern Iraq alongside northern and eastern Arabia (2009), southern and southwestern Iraq (2010), western, southern, and northern/eastern Iraq alongside Arabia (2011), and again southern and southwestern Iraq (2012-2013). In 2014 and 2015, northern and eastern Arabia re-emerged as the primary source. Finally, the Iraq-Syria border, western Iraq, and southern Iraq were identified as dominant sources in 2016 and 2017, respectively. Across the entire study period (2003-2017), eastern Iraq, the Iraq-Syria border, southern Iraq, and northern and eastern Arabia emerged as the most significant dust source regions impacting Khuzestan.

Our analysis revealed that Iraq contributes the highest proportion of dust emissions impacting Khuzestan province (68.8%), followed by Saudi Arabia, Syria, and Kuwait. Considering anticipated climate change and intensified dam construction activities in upstream countries, particularly Iraq, dust generation will likely worsen. The dust originating from these regions, situated along the path of synoptic systems towards Iran, has significantly impacted the environment, especially the Zagros forests. Identifying the primary dust source areas empowers policymakers to develop tailored and effective diplomatic strategies for controlling and mitigating the effects of regional fine dust.

Wind erosion and dust phenomenon are considered as one of the important processes of land degradation and a serious challenge in Iran. This phenomenon occurs due to the interaction between weather and terrestrial processes. The purpose of this research is to investigate and analyze the trend of temporal and spatial changes in the number of dusty days in Iran and to investigate the role of climate in its spread.

In this research, after receiving hourly and daily statistics of dust events (through 148 synoptic and climatology stations) and parameters of precipitation, evaporation, temperature as key climatic elements (from 171 stations) in 22 provinces located in arid and semi-arid regions of Iran, The spread of dust was investigated and the correlation between climate and dust was determined. After calculating the number of dust days in Iran, the information was called in the GIS environment and a map of the spatial changes of the parameter of the number of dust days in the three decades of 1987-1996, 1997-2006, 2007-2016 was prepared. In the following, the spatial analysis of this parameter and its expansion over three decades were investigated. Next, the climate parameter that had the highest correlation with the number of dusty days was selected and after preparing a map of its spatial changes in the GIS software environment, the spatial compatibility of the desired parameter with the expansion of the number of dusty days was investigated. In the next step, after performing the homogeneity test on the dust occurrences, the partial square regression model was used to determine the contribution of the three mentioned climatic elements as independent variables and the number of dust days as a dependent variable.

The results showed that the number of dusty days and the area of its occurrence have increased in Iran, so that in the last decade under study (2007-2016) compared to the previous two decades, the dustiest event occurred in Iran. This increase has been more intense especially in the western and southwestern regions of the country, which were also affected by extra-local dust events. These dust events have spread to the central regions of the country with greater frequency. The homogeneity test in many provinces showed a common change point (year 2007-2008) in the number of dusty days, which could be related to the beginning of severe droughts and climate changes from this year in Iran. The study of climatic parameters (temperature, precipitation and evaporation) on changes in the number of dust days in Iran showed that during recent years, temperature had the highest significant correlation level (0.58) with the occurrence of dust. The temperature gradient map in the last decade (2007-2016) compared to the previous decade (1997-2006) also showed the increasing trend of temperature, especially in the western and southwestern regions as well as the southeastern regions of Iran. Modeling the effect of climatic parameters of temperature, precipitation and evaporation on the parameter of the number of dusty days showed that the contribution of the studied climatic parameters to the occurrence of dusty days is about 33% and other effects can be related to things such as human factors or soil characteristics, type of vegetation, solar radiation, etc.

In general, the results of examining the trend of changes in the number of dust days and climatic indicators for nearly 3 decades indicate a significant increase in the number of dust days in most parts of Iran and the conditions for this increase have been provided and if the trend of changing these indicators in the coming years is according to the current trend, the risk of environmental problems in the country can be expected to increase.

This study provides an applied method to estimate the land sensitivity of wind erosion in the Hamoun-e Baringak Sistan, as an ephemeral lake. Due to the wide extent of the sources of dust and sand production in Sistan, finding areas that are prone to wind erosion is of paramount importance in prioritizing stabilization. For this purpose, indices of transport rate (erodibility), soil shear strength, and SAVI were conducted.  To investigate the land erodibility to aeolian transport, 74 graduated pins were embedded randomly in the ephemeral Baringak Lake bed and the aeolian transport rates were measured for the total study period. The shear strength of the soil surface was measured using Torvane. The vegetation canopy density was extracted from digital images using the SAVI index. The results showed that there is a very significant relationship (1%) between soil shear strength and SAVI indices with transport rates. It means that this proposed method may be also applied to estimate land sensitivity in environments instead of threshold friction velocity of wind erosion in the field. Comparison of the results of regression model estimation with transport rates in the field were significant.

Recently, Khuzestan province has been faced by dust storms with a higher mass concentrations and longer durations. Providing the water needed to irrigate the seedlings is one of the basic needs. The potential for runoff production at dust sources has been evaluated in the present paper. For this purpose, the volume and depth of runoff were determined based on the area's hydrologic soil group, vegetation cover and land use layers using the US Soil Conservation Organization (SCS-CN) method at the unit level of the studied areas.The results showed that most of the dust centers with an area of 643300 hectares are covered by barren lands with low vegetation and an area of 522,300 hectares is also included in the hydrological soil group C and D. The calculations derived from the amount of runoff generated in the dust center showed that in South East Dust Center of Ahvaz in the November to January quarter per hectare respectively 80, 120 and 95 cubic meters of water can be extracted. It is possible to produce runoff in the Omidieh-Hindijan dust center in December and January from about 60 to a maximum of 160 cubic meters per hectare, in Hoor Al-Azim-Khorramshahr dust center from 30 to about 80 cubic meters per hectare in the second half of the year and in the place of planting projects that the necessary arrangements must be made to manage the use of this possibility).

Iranchr('39')s location on the arid world belt, the occurrence of climate change and global warming and the increased in human interference have resulted in dust storms phenomenon in the western and southwestern parts of the country, especially in Khuzestan province. The present study has been aimed at investigating the existing water resources of the province for the watering operation of the southeastern dust source of Ahvaz with the first priority for providing A quick solution. Since this site is located within the catchment area of the river of Koopal, to study the discharge rate and its runoff the station of koopal number 3 was selected and its average discharge and rainfall were surveyed during the years 1982 - 12014 and 1982 – 2012 respectively and the soil conservative service method of USA along with GIS and RS tehniques were used.The results showed that the average annual discharge rate of the Koopal River was, 2.49 m 3/s, so that the highest was in winter and the lowest was in summer. On the other hand, the results showed that the studied area from the southeast of Ahwaz can produce an annual runoff volume of 34.14 million cubic meters Which is 31 million cubic meters in fall and winter seasons. Therefore, regarding the annual runoff volume of koopal River and the southeast dust source of Ahwaz, especially in the winter season because of the increasing in the frequency of south-eastern wind as the main cause of dust storms phenomenon, to carry out the operations of watering and restoring vegetation cover with a proper management water usage plan in the upstream of the river.

Shadegan International Wetland is one of the most important environmental assets of the country due to its very high biodiversity and diverse functions. Awareness of wetland changes is one of the basic needs in the proper management and exploitation of this valuable ecosystem. In this regard, remote sensing methods are a useful tool to study and detect changes in wetlands. Therefore, in this study, with the aim of investigating the trend and revealing the changes in Shadegan wetland, Landsat TM, ETM + and OLI satellite images of 1988-1998-2007 and 2017 were used. Three stages of preprocessing, processing and post-processing were performed on the images, Supervised vector classification (SVM) was used and the images were classified into three classes of water, vegetation and without cover or soil. Classification accuracy for images was calculated using two indicators, overall accuracy and kappa. In order to reveal these classes, changes in 9 classes were analyzed. To show the changes, the graph revealing the changes of uses in three time periods was used. The results showed that in the period 1988 to 1998, water area increased by 1.5% in 1998 and vegetation increased by 5% and soil or uncovered area decreased by approximately 7%. Between 1998 and 2007, water area increased by 4% and vegetation decreased by 20%, and soil or uncovered area increased by approximately 15%. In 2017, there was a 7% decrease in water, a 36% decrease in vegetation, and a 30% increase in soil or uncovered area. This study demonstrates the need for immediate attention to the conservation of wetland residual resources for sustainable use for the next generation.

The Middle East, Iran and Khuzestan are located on the dry belt of the world and the dust phenomenon is one of its inherent characteristics. Long-Term survey of synoptic stations in Khuzestan Province shows that dust phenomenon with domestic and foreign origin has existed since 50 years ago; however, the share of internal and external resources of dust is not determined by a scientifically valid method. The occurrence of dust phenomenon is reported at each meteorological station every three hours with different codes. If the dust observed is from the source outside the station and comes from another area, it is reported with code 06, but if it is caused with the rise of dust in the area and around the station, it is reported with code 07. In a 15-year common statistical period (2002-2016), the data of dust codes were extracted for 12 synoptic stations and the dust with internal origin was separated from the external origin. Overall, the results showed that the share of internal and external resources was 8.4% and 91.6%, respectively. The output of results was zoned and analyzed using the usual Kriging method in the GIS software environment. Long-term changes in internal and external events at the Ahwaz station, indicating the highest occurrence during the total statistical period (4876), showed that the share of foreign resources increased sharply in recent years.