طاهره انصافی مقدم

The phenomenon of dust storms has become a global environmental challenge. As a natural disaster, it has significantly affected Khuzestan province due to its geographical location and proximity to vast desert areas. This study aims to examine land management strategies to mitigate dust production in the southeastern dust source of Ahvaz by implementing effective land management techniques to control wind erosion in this region.

To conduct this research, ecological land resources—including climate, geology, soil properties, land use, vegetation cover, wind erosion, and agricultural and livestock conditions were analyzed using satellite imagery and extensive field surveys. By overlaying maps, the dust source area was classified into ecologically homogeneous units (work units). Based on the physical and chemical properties of the soil, the vegetative potential for biological stabilization was determined according to the ecological requirements of native plant species. Soil samples were collected from 106 points at three depths, and soil erodibility was assessed using a wind tunnel. A wind erosion sensitivity map was then generated to prioritize the stabilization of work units. The characteristics of erosive winds were analyzed using hourly wind speed and direction data from 21 meteorological stations. After creating a database of ecological resources in a GIS environment, the vegetative potential of the work units was evaluated using soil properties. Subsequently, specific stabilization projects were proposed for each work unit.

The findings of this study indicate that the stabilization strategy was planned systematically, considering the ecosystem type, and dust control projects were designed based on land use classifications. The land use distribution of the dust source area includes 37% rangelands, 10% bare lands, 11% dried wetlands, 24% rainfed agriculture, and 13% irrigated agriculture. The proposed projects included biological measures such as shrub planting, afforestation, roadside tree planting, and living windbreaks along farm edges, as well as management strategies such as soil moistening, leaching, irrigation, grazing control, construction of non-living windbreaks, and rainwater harvesting techniques. Analysis of the energy trend of erosive winds over the past decade revealed no significant changes. Instead, the activation of dust sources was attributed to land use changes, precipitation patterns, and drought occurrences.

The lack of water allocation to downstream ecosystems, combined with the construction of large dams and multiple watershed management structures in upstream areas, has led to the transformation of wetlands and sedimentary plains into major dust sources and has contributed to surface soil salinization. Restoring flood capacity in these areas was achieved through the construction of water supply channels to meet the water demands of biological stabilization projects and facilitate the moistening of wind erosion-sensitive units. Overall, the implementation of these projects demonstrated that this ecosystem restoration-based approach, with a focus on wind erosion-prone lands, can serve as an effective model for stabilizing the country’s dust source areas.

Urban river valleys are natural corridors and aquatic habitats that provide an enlivening landscape for Tehran and play an essential role in environmental, social, and cultural issues for urban residents and development in their lives and their area. The structure and function of these valuable elements have been ruined due to non-planning growth. Regardless of environmental subjects in municipal management and Tehran landscape planning, they have been converted to the runoff canal network or effluent. The main rivers of Tehran are Vardavard, Kan, Farahzad, Darake, Darband, Golabdareh, Velenjak, Darabad and Sorkheh Hesar. This paper aims to elaborate on the natural structures of the river valleys of Tehran with specific consideration of 9 river valleys and to familiarize with the crossing route of the urban river valleys of Tehran from their neighborhoods and some of the high-risk areas during floods, which will be realized.

The purpose of this paper is to identify the patterns used by of spatial distribution of moisture flux in rainy days in the southwestern stations of Iran. For this purpose, the codes of the current weather conditions transmitted by the stations located in seven southwestern provinces of Iran during the period of 1986-2016 and the most important cases of daily rainfall were examined in the thirty-year period in the region and were obtained a classification based on Geographies distribution from the maximum daily precipitation. In this study, ten case maps, which are based on gridded data of temperature, sea level pressure, geopotential height (HGT), component result Orbital (U) and meridional (V) winds and arrangement of vertical velocity patterns (Omega) prepared at different atmospheric levels from the United States National Oceanic and Atmospheric Sciences Base (NCEP/NCAR) databases (1986–2016) has been analyzed. The results indicate that in patterns with south to southwesterly currents, the low-pressure surface center extends from the south of the Red Sea to southern Turkey and is associated with the mid-level trough, where the moisture fluxes converge in the south of the Red Sea, southwest/south of Iran, and east of the Mediterranean Sea. On the other hand, the spatial distribution patterns of heavy rains are directly related to the topographical factors in the atmospheric conditions of the humid westerlies. In this study for investigating moisture flux patterns, meteorological data at 45 synoptic stations were studied during recent 30 years. «First of all, occurrence of daily rain is classified and then genesis and severity conditions of them were considered from the synoptical view point. Then prediction of time and spatial occurrences of daily rain is the major object of this study. Then using circulation under environment approach, the most important of patterns which play key role over climate of southwest provinces of Iran were classified. In the first step the "mean daily sea level pressure data were selected from the NCEP reanalysis data encompassing the region from 20°-60°N latitude by 20°-80°E longitude, with a 2.5 spatial resolution and for the 30 years period 1986-2016 in moisture flux. Selected territory is located in a geographical situation that covers all the effecting systems on Iran. For classification and delineate synoptical patterns Principal Component Analysis (PCA) and clustering method were used"(Kianipour et al., 2022).Results and Discussion Study of 10 selected moisture flux and rainfall samples show that extracted information presents general synoptical patterns. Any type pattern was studied at sea level pressure and 850 hPa level as follows. Results showed that in this region, "the moisture flux have three general circulation patterns. Analyzing these patterns show that there is a trough which restricted to 30-45°E longitude in 850 hPa chart, and at least one relatively strong low pressure over Arabian Peninsula in sea level pressure extending to the west, south west and the study region. This study shows that above aspects are the major specifications of moisture flux (Kianipour, 2022)." Based on the results, the presence of low pressure over the western Kazakhstan and high pressure over the Arabian Sea and low pressure in eastern Arabian Peninsula, play key roles in moisture penetration into Iran and increasing atmospheric moisture"(Golkar et al., 2016). This study has classified the synoptic patterns affecting Iran and the Middle East from 1986 to 2016, for all seasons months and days and with a higher accuracy using data with 0.5° resolution on a daily time scale. Then, composite maps of the mean sea level pressure (MSLP), and 500 hPa geopotential height (GPH) were prepared and analyzed. Previous studies have focused mainly on 500 hPa and MSLP parameters. «However, in the present study, the 850-hPa moisture flux, which was considered an important quantity for the precipitation occurrence, was calculated and analyzed in each of the patterns»(Raziei, 2007). One of the conditions in forming moisture flux is existence of a trough in 850 hPa charts, between 30 to 45°E longitudes that extends at least to 25°N latitude and lower. Because of cold advection in behind of the trough from mid-latitudes to the south, and warm advection in ahead of it from south latitudes to the north, increasing of pressure gradient and wind velocity at ground surface is observed. Existing at least one relatively strong low pressure on the north of Saudi Arabian Peninsula at sea surface charts, associated with a trough over red sea or west of Arabian Peninsula at 850 hPa level, and extending to the west, south west and the region under study in Iran. This situation is one of the most important specifications of moisture flux. This low pressure cause to increasing pressure gradient on the north of Saudi Arabian Peninsula and south west of Iran. Position of troughs at 850 hPa level are in a form that they can lead and send the air masses from deserts in north of Saudi Arabian Peninsula, Iraq, Syria and Jordan to Iran. Because these areas are at the front of the trough which is very unstable (Kianipour, 2022).

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.

While the Greenhouse gases impacts of Powerhouse، cars، and other man-made particulate matter on air quality and public health، well known، their impact on climate is not fully understood. Scientists have shown that aerosols can lower surface temperatures either directly، by reflecting sunlight skyward، or indirectly، by increasing the reflectivity of clouds، but until now have not figured out the role airborne particles play in shaping the distribution of rain and snowfall around the world. Suspended dust particles, especially in urban and industrial areas, act as a reducing agent for rainfall. Large fine dust (larger than 1 micron) can increase rainfall. But very fine dust particles in the upper atmosphere can suppress heavy rainfall. The current study aimed at investigating atmospheric precipitable water capacity and its relationship with periods of dust occurrences data in South west of Iran during (1986 –2016). In this paper، MODIS surface classification data was used to consider this influence. In this paper، the effect of dust occurances on rainfall studied by using classified data of MODIS/Terra Calibrated Radiances (MOD06). The results of this study by examining remote sensing data such as the amount of atmospheric precipitable water content and the occurrences of dust in some selected cases، showed that over time when dust rises، the amount of atmospheric precipitable water content which indicates the potential for rainfall، significantly reduced.The results of this study showed that one of the effects of dust events in southwestern Iran، there was a decrease in rainfall during a period of thirty years(1986-2016) and dust can significantly to act as reducing agent or rain suppressor in study region. On the other hand، in this study، in proof of dust reducing effect on atmospheric precipitable water content، the high performance of the MOD06 product appeared in the southwestern region of Iran.

In recent decades, dust storms have intensified due to climate changes, including drought and human interventions. In addition to removing soil particles, dust brings storms bring about severe economic, social, and health problems. Due to its strategic conditions – including its status as an industrial and agricultural hub and the province hosting more than 29 million Iranian and international pilgrims, especially during the seasons and months with specific holidays – should be prioritized in the examination of dust storm frequency. The purpose of this study was to examine and track the frequency of dust storms and analyze the effect of climactic changes on them through the investigation of drought trend as well as the trend of changes in the land surface coverage percentage during the statistical analysis period. The results of counting the dust codes showed that dust storms with local origin had the highest frequency. According to the monthly analysis, Sarakhs and Mashhad stations had the most dust phenomena, with the most dusty days in the study area during summer and spring seasons, especially June and July months. The results of regression analysis of drought index and the monthly local dusty days indicated the existence of a significant, positive relationship between dust increase and drought intensity in Mashhad and Sarakhs stations during the statistical period of 27 years at 99 percent confidence interval. Finally, in the light of the results obtained from the examination of the land surface changes, it is recommended that land use plans be used along with short-term methods of soil stabilization in order to reduce the economic damages and preserve people’s health against dust during busy months and seasons so as to achieve the goals of long-term methods.

Desert dust is an important risk factor to human health in the southwestern provinces of Iran. This study is an attempt to highlight the relationship between changes in optical depth values extracted from the Deep Blue algorithm with the frequency of dust events in meteorological ground stations which is located in seven provinces of Ilam, Lorestan, Chaharmahal and Bakhtiari, Kohgiluyeh and Boyer-Ahmad, Khuzestan, Bushehr, and Fars For this purpose, the number of days with dust and daily data of dust events, and daily horizontal visibility were obtained from 45 meteorological stations in the fifty-year period (1966 to 2016) and analyzed. The results showed that the average annual number of days with dust increased after 2000. This figure is estimated at 82.3 days in the first decade of the trend, 46.3 days in the second decade of the trend, 84.6 days in the third decade of the trend, and 71/1 days in the whole thirty-year trend. The most severe dust conditions during the period under review were 2009 and the lowest dust conditions were in 1994. In order to verify, the AOD product was compared with the frequency of severe dust events of the Meteorological Organization. There was a perfect agreement between the temporal and spatial distribution of the dust concentration in AOD images and the temporal and spatial distribution of the frequency of dust events at meteorological ground stations. The highest annual average AOD was fully consistent with severe dust events in 2008 and 2009, as well as the most severe dust events in the summer.

In the present study, the Miqan sub-basin of the Arak region was quantitatively investigated to find out the temporal and spatial variations of groundwater level in the nine Qanats (subterranean canals).  The methodology to evaluate the spatial and temporal changes of groundwater level,  the  26 years data of changes in underground water (1365 -1390) produced by the Water Authority Bureau of Arak city for the Miqan-sub-catchment were collected and analyzed using GIS software and time series methodology processing of data. In this methodology, firstly the mean of water discharge and withdrawals of qanats water for daily, monthly and annually were analyzed and monitored.  Then the trend of changes in the water level of all investigated wells for the 26 years data was graphically determined for those time series respectively. Secondly, a group of hydrograph for this sub-catchment were presented in figures and compared for all-time series based on daily, monthly, seasonally and annually respectively mentioned in the paper. Linear regression (simple linear) and Mann-Kendall statistics method were used to test the significant trend of changes in the underground level for all the periods' mentioned above. In the last stage, to produce the sub-catchment maps for showing the groundwater hydrograph of the plain, interpolation on maps was performed using ARC GIS software. The results indicated that according to the hydrograph of the 26 years of groundwater level has decreased drastically. Available hydrogeological data also show a sharp drop in aquifer water levels in recent years. The maximum rate of decline has been observed in the central parts, located below the Miqan basin. The most important reasons in increasing the rate of groundwater level are the mismanagement and uncontrolled withdrawal of groundwater resources by resident farmers and also the frequent reduction of precipitation

Evapotranspiration is one of the most important outcomes in the water balance equation for any natural area or water body. It is also a crucial component of the hydrologic cycle. The main purpose in this research was to detect the changes generated in the study region’s water balance for climate impact assessment by using statistical analysis. To reach this purpose, following steps were done. The relationship of temperature-evapotranspiration was obtained using the Thornthwaite method in Arak plain. The parameters including actual evaporation and soil moisture content in this area were estimated using the Thornthwaite model for each month. Remaining parts of water balance equation including: actual evapotranspiration, soil moisture supply of the area in each month and later months were estimated from Thornthwait model. The net water requirements were estimated using the model by assuming that evaporation was the only path for water loss. The results indicated that the timing of recharge was very important in preserving plain hydrology in this region. This modified climate diagram prompts an intuitive understanding of the relationship between recharge and consequent wetness in Arak plain. It may be used as a standard tool for determining adequate water demand in arid regional water resources management that considers wetland protection or restoration.

This paper was carried out to determine the cycle of dust storm in relation with precipitation in 12 months of the year, using processing of digital time series and their correlation with two variables mentioned above. Hence to accomplish the aim of the paper, the frequency of time series for dust storm and rainfall have been analyzed for the long time statistical data collected from 45 synoptic stations(1986-2016), located in the south east of  Iran. In order to understand whether or not any correlation with these two variables, firstly a diagram of the daily changes in dust storm and rainfall cycles was drawn for each month separately. Then, to make sure that the statistics data are normal, the data were analyzed using Kolmogorov-Smirnov test in SPSS software. The results of data normality showed that all statistical data of the parameters used in this research were normal. The results of calculating the correlation coefficients of each month during the course of thirty years, indicated that the correlation of data are significant at (P<0.01 & P<0.05) only in the cold months of the year (January, February, March, April, May, November and December). Also, this study showed that the relationship between the amounts of daily precipitation with an abundance of dust events in the area was negative, and this indicates that the dust could be significantly as reducer or repressive downpours in the region.

Dust in the atmosphere and their interactions with precipitation have great impacts on regional climate where there are large arid and semiarid regions. Dust is one of the factors affecting precipitation. There are many ambiguities about the cause of the difference between amount of rainfall from an area to another area and from time to time. So that even with the spread of knowledge and technology yet still there is not completely specified the cause of these fluctuations. Nowadays, satellite images are broadly used for monitoring the effects of dust variations on the precipitation changes. Nowadays, satellite images are broadly used for monitoring the effects of dust variations on the precipitation changes. The aim of this study was to investigate the relationship between dust dynamic and precipitation variations. This research can be help to find the impact of dust occuarrances on precipitation changes in the South-West parts of Iran during thirty years by cluster analysis, remote sensing, and aridity zoning in GIS software. In this investigation, we analyzed data sets of daily average visibility(a proxy for surface aerosol concentration), daily No of reports frequency of dust occurance and daily precipitation at 45 meteorological stations during past 30 years(1986-2016)were obtained from the Iran Meteorological Organization. The consistent trends in observed changes in visibility, precipitation, and daily No of reports frequency of dust occurance appear to be a testimony to the effects of dust. In present study, we tried to determine the relationship between dust events data and measured precipitation changes in a ground stations. Therefore frequency of dust occurrence from 1986 to 2016 at 30 stations, compared with rainfall anomalies for South-West of Iran as a whole. Rainfall is expressed as a regionally averaged, standardized departure (departure from the long-term mean divided by the standard departure), but the axis of the rainfall graph is inverted to facilitate comparison with dust occurrence. Dust is represented by the number of days with dust haze. Then‚ dust days ratios which measured by number of days with dust in month and horizontal viewing which measured by number of days with visibility min

This study was designed to evaluate the presence of some heavy metals in dust as well as their influences on soil, leaves and twigs of Brant`s oak (Quercusbrantii Lindl.) at a study site located in Meleh-Siah, Ilam province. For two groups intact and declined trees, we measured four elements including Pb, Zn, Ni and Cd in twodifferent time spots (April and September 2013) during the growth period corresponding to the dust events. Sampling results showed an increase in the amount of all elements except for zinc in the sub-canopy soil for both groups of trees. By showing a significant increase (p

The present study firstly sets out the procedure for the generation of climatic files for localities with climatic records and secondly, The process of obtaining maps of the climatic zones for all of the localities in the Salt Lake Basin of Iran. For the generation of the climatic records such as rainfall periods and intensity, provided by the 34 climatology stations for a total of 44 years data from (1957-2000), was used as a source of information. These data was then subjected to a statistical analysis, using SPI method for the calculation of the frequency, intensity and duration of drought process. Finally for the mapping drought zoning in all localities of the Salt Lake Basin for the long term period, the Inverse Distance Weighted Method(IDV) was used in the Arc view software environment. The results showed that the study area is very sensitive to climatic drought.

Many climatology scientist adopted temperature and precipitation among all climaticparameters to identify desert regions from non-desert areas. There is no one definition of a desert that is accepted by all. The boundaries of a desert change radically depend on the variance in the range of proposed criteria definition accepted. Thus this study was carried out to identify the boundaries of a desert territory from non-desert regions using climatic data such as total precipitation, average intensity of daily precipitation, annual average temperature and evaporation together with the coefficient of variance and seasonal concentration. For each climatic factor a digital map was produced for all studied provinces using Geographical Information System (GIS). By overlaying all digitized climatic factors a transitional strip of boundary was recognized and then its accuracy was checked with field data and topographic map. Based on this boundary strip, three zones were recognized as 1- true desert zone located inside the strip of boundary.2- non-desert area, outside of the boundary and 3-Semi-true desert zone located in the boundary strip itself. It was concluded that true or natural desert that known as climatology desert are 700991 km2 or 42.5 % of the Iran map.

Of the many Climatic events that influence earth’s environmental fabric‚ drought is perhaps the one that is most linked with desertification(WMO‚1997).This Investigation is an effort for assessment of acceptability about many of Climatic current Drought Indices in reagent and sample stations of Salt Lake Basin of Iran. These drought indices which are used in world active systems, are Percent of normal precipitation Index PNI, Deciles of precipitation Index DPI, Standardized precipitation Index SPI, and Z Score Index ZSI.The above mentioned indices were calculated first by average of monthly precipitation data for a 44 years period from 1957 to 2000 relate to 34 synoptic and climatological stations in their common time scales. Based on obtained results from one hypotheses, DPI and SPI indices in the contemporary with minimum occurrence, showed, extremely drought in the studied stations. These acceptability of indices in more than of other indices and according of this investigation,DPI index sit on the first place, SPI sit on the second place, ZSI index sit on the third place, and finally PNI Index, sit on the forth place. In next stage the Standardized Precipitation Index SPI, based on precipitation values from 34 monitoring stations around the Salt Lake Basin of Iran, is computed monthly and was performanced for climatic interpret and characteristic include assess drought relative frequency, intensity, expand and duration and calculated return period of the most intense drought and according to the point stations data, drew intense map. This investigation indicate the most intense drought in Salt Lake Basin of Iran belong to Hamadan(Nozheh) and the longest drought duration in Avaj ‚Dooshantappeh‚ and Kashan Stations with the highest relative frequency digit of drought (38/6%) and the lowest relative frequency digit of drought (18/1%) belong to Golpayegan. The most of severe year has occurred in 1973 and 1967 in 44 years period.

Salt Lake Basin of Iran which is situated on the arid and semi-arid climatic region and located at central Alborz southern slopes, covers an area of 92750 sq km and lies between 33º till 37° northern latitude and 48° till 52° 30´ easthern longitude. Salt Lake Basin of Iran according to “Country Water Comprehensive project” Classification, has been specified under the title: “The seventh Basin”. This basin consisted of 7 provinces: Tehran, Qazvin, Zanjan, Qom, Hamadan, Markazi province and some parts of Isfahan Province. In order to analyze of meteorological data, the statistics of one long-term time series past 40 for the years, from 1957 to 1996, were extracted for the 35 stations on this basin, for the climatic parameters which was studied in selected meteorological stations, consist of monthly precipitation, maximum daily precipitation, monthly maximum temperature average, monthly minimum temperature average, absolute maximum temperature, absolute minimum temperature. Meteorological data calculatefor one long-term time series 40 years indicates, rainfall average of Salt Lake Basin, is 256.5 mm and rainfall variability average is 35.11%. The Rainfall variability average of Salt Lake Basin, during 40 years differs between 22.1% in Malayer and 62.4% in Doozaj and annual precipitation disorder coefficient differs between 8.3% in Zanjan and 38.9% in Kavir. Annual mean temperature during 40 years is 13.9 °C. Absolute maximum and Absolute minimum temperature are 48°C and –35°C. Temperature variability average, during 40 years is 11.49°C. Aridity coefficient average during 40 years has been calculated to 11.092 and the regional climate average is Semi-Arid according to the method of Demartonne.