فصلنامه پژوهش های فرسایش محیطی
سال یازدهم شماره 3 (پیاپی 43، پاییز 1400)

Coastlines are defined as the contact line between land and water body and have strategic natural, social and economic importance. One of the most important features of coastal areas is their dynamics. These dynamics lead to advances and regressions along the coastline and lead to erosion and sedimentation in the coastal regions. Coastline changes are one of the significant threats to coastlines. The study area of this research is on the southeastern coast of Makran and between Chabahar and Quatre Bay. This region is of special strategic importance today. The study area is divided into three geomorphological units of marine terraces, sandy beaches, and coastal barriers. The rate and trend of shoreline changes in each of these units were investigated to determine the stability of each geomorphological unit and evaluate and suggest suitable areas for future development. In addition, the future trend of changes in this regionchr('39')s sensitive and strategic areas in some important parts of this region in the next 10 and 20 years will be evaluated.

The purpose of this study is to investigate the changes in coastlines of the study area. Hence, shoreline changes through shoreline monitored between 1989 and 2020 using Landsat (TM) satellite data (1989, 1995 and 2010, ETM for 2001 and OLI 2015). The extracted shorelines were entered into DSAS software, and shoreline changes were evaluated in this system in ArcGIS software. In this study, endpoint rate (ERP), linear regression rate (LRR), shoreline displacement rate (NSM), and shoreline average change (SCE) indices were evaluated. In addition, the prediction of shoreline changes was examined in the next 10 and 20 years in areas of great importance for development.

 Results :

One of the purposes of studying coastline changes is to study the sustainability of the coastline to plan for coastal development. Identifying stable and unstable areas along the coastline allows planners to identify areas that have the potential for development in terms of establishing coastal structures and minimizing the risk of future natural damage to coastal structures. Therefore, the study of coastline changes is one of the important parameters in these programs. This study was examined separately to analyze better the shoreline changes in each of the geomorphological units. The average changes were prepared according to LRR, EPR, NSM, and SCE values ​​in each unit. The results show that the highest amount of shoreline changes is observed in the coastal barriers of the study area. The average rate of change in coastal barriers in the LRR index in coastal barriers is 2.75 meters per year, which shows the ratio of sandy beaches (0.03 meters per year) and high beaches (0.11 meters per year) is very high. In addition, according to the NSM index, maximum advance (399.55 m) and the highest regression (725 m) can be seen in the geomorphological unit of coastal barriers, while the average values ​​of NSM on the sandy beach for shoreline are 103.7. the maximum regression rate is about 49.5 meters between 1989 and 2020. In addition, the NSM index values ​​for the terraces beaches are 36 meters forward and 41 meters backward, respectively.

Changes and instability of coastlines are some of the major challenges that planners face in developing coastal structures, and not paying attention to these changes in the past and its future trend can impose irreparable damage to development projects. The present study was conducted in a very important area of ​​Chabahar to Goater to evaluate the stability of coastlines using periodic satellite data and DSAS tools. The results showed that the NDWI index separates the water area from the land better than other indicators. This study showed that the analysis of shoreline changes in the coastal region could be more accurate when geomorphological units in the coastal zone are separated and shoreline changes in these areas are evaluated. The results show that the two coastal areas and sandy beaches are relatively stable. Thet changes have occurred in sand dams, which can be attributed to the simultaneous effect of morphodynamic factors of land and sea in this area. Therefore, in the development of beaches and the establishment of coastal structures, coasts have risen, and also sandy beaches can be among the priorities of coastal planners in these areas. In addition, the structures constructed in the coastal zone have greatly impacted changing and intensifying the processes of erosion and sedimentation. Its example can be seen well in the port of Chabahar and Beris, which can cause problems in the future in the field of exploitation. It created ports.

Global warming has occurred in recent decades, and its warming trend will continue due to increasing concentrations of atmospheric greenhouse gases from human activities. Changes in the average rainfall in many areas have also been recorded in connection with global warming due to rising atmospheric humidity. Climate change is another threat to the security of water resources. Therefore, climate change has a significant impact on the hydrological cycle on a global and local scale. The issue of understanding climate change is of particular importance for areas dependent on seasonal water availability and areas exposed to vulnerable climates. On the other hand, Iranchr('39')s geographical location in the subtropical region has caused it to be located in the dry belt of the world. Due to this geographical location, the average rainfall in Iran (255 mm) is much lower than the global average (860 mm). A noteworthy point about Iranchr('39')s rainfall, in addition to low rainfall, is its high variability. On the other hand, in the last century, global climate change has been reflected in increasing temperatures, increasing precipitation changes, and decreasing glacial and snow regions.

This study was conducted in the southern region of Kerman. In this study, the first daily temperature and rainfall data of Jiroft and Kahnooj synoptic stations were prepared by the Kerman Meteorological Organization to investigate climate change during the period (1989-2017). After collecting data, SDSM4.5 software was used to study climate change and the trend of these changes.

The results of the performance of the CanESM2 model for its ability to microscale exponential parameters of precipitation and average temperature during the base period indicate that this model has a high capability in simulating climate change in the south of Kerman province for the period (2050-2021 and 2080-2021) .According to the exponential microscale results, the average temperature has the best performance relative to the daily precipitation, which can be one of the reasons that the temperature changes relative to the precipitation change over a period of time, while the precipitation parameter fluctuates widely. According to the three evaluation criteria of NSE, RMSE, and R2, the performance of the CanESM2 model is in a very good and good class. The results show that the temperature changes in both periods and both stations are incremental. However, the changes in rainfall in each of the scenarios did not follow a specific rule and are increasing and decreasing.The results show that the average temperature during the period (2050-2021) in Jiroft synoptic station indicates that under the scenarios of RCP2.6, RCP4.5, and RCP8.5, respectively, 1.63, 1.61 and It rises to 2.06 ° C. These temperature changes in the period (2080-2051) are also positive. Following the mentioned scenarios, the temperature will increase by 2.02, 2.88, and 4.23 ° C. The results of temperature change and precipitation in the base period (1989-2017) showed that in the base period for synoptic stations of Jiroft and Kahnooj, the temperature parameter due to the P-value value is less than 0.05, which means that this trend also includes Kendallchr('39')s tau and age line slope. The trend of temperature changes in the future in both stations is significant and indicates an increase in temperature in the future. Also, changes in precipitation in the base period in Jiroft synoptic station are without trend.On the other hand, these changes in Kahnooj synoptic station are significant and decreasing. In the next period, rainfall in Jiroft synoptic station is without trend. The results also show that only in the period (2080-2051) in the RCP4.5 scenario in Kahnooj station, its precipitation trend is significant and decreasing.

In the present study, to study climate change in the south of Kerman province, the model of the fifth report of the International Board of Climate Change CanESM2 and new release scenarios in the next two periods (2080-2051 and 2050-2021) were used. Also, to clarify the trend of annual changes in temperature and precipitation components as inputs of hydrological models, a non-parametric Mann-Kendall test was used. The results of evaluating the accuracy of the CanESM2 model showed that this model has good accuracy in both temperature and precipitation components in both synoptic stations.. On the other hand, the trend of temperature changes in the future indicates that temperature changes have had an increasing trend.

The Earthchr('39')s environment and ecosystem is an extensive and complex set of different components and factors that have been formed as a result of the gradual evolution of living organisms and the components of the Earthchr('39')s surface. This collection includes nature and all living things. As one of these beings and a part of the environment, man is affected by nature and is also affected by it. This effect, which manifests itself in various forms, is mainly due to the various activities. From the past until now, nature has been used and exploited in multiple ways. As a result of this impact on the environment, it has mainly manifested itself in the form of degradation and has increased in recent decades for various reasons. This issue means that the increasing trend of exploitation of nature, due to the intensity and nature, causes various concerns that manifest themselves in the form of ambiguities and essential questions. In the general case (exploitation of nature), the general and key questions are what mechanism follows this growing process of exploitation of nature, to what extent it is correct and logical, and the primary purpose of this exploitation?One of the forms (types) of use and exploitation of nature globally and in Iran is mining activity. Naturally, the general and key questions raised above, both in general and in the discussion of specific uses (here mining activity) can be examined and explored. However, in recent years, this activity can be examined in various situations (in terms of exploitation intensity and increasing mining trend. But it seems that a general explanation and the nature of the action and activity, not based on the intensity of activity, also has sufficient credibility and an excellent position. Is. However, as stated, the purpose is to investigate basically and in general the relationship between nature exploitation in Iran in the form of mining activities with nature? Basically, in this regard, the only and always the aforementioned goal in such industrial (economic) activities, or does nature itself have a place and importance in this? This study aims to provide an appropriate answer to the key question that to what extent economic activities and exploitation of nature, mining here, are in line with naturechr('39')s capacity and follow the principles of sustainable development? In summary, the present study seeks to properly assess the environmental sustainability or instability of mining activities and, in this regard, the degree of proportionality between the positive (mainly economic) and negative (mainly environmental) effects on the environment of residents in affected areas. To become clear.

 In summary, the recent research was carried out in several stages as follows: In the first stage, based on the nature of the issue and attention to factors such as the proximity of the mine to residential areas and people, as well as the importance of different factors affecting the mine and Bastak area and In particular, Paytaveh gypsum mine was designated for research. In the next step, general and specialized questionnaires were designed by considering different aspects of my impact. A general questionnaire for surveying the general public and, in fact, residents of areas adjacent to the mine, and a specialized questionnaire for obtaining more technical and comprehensive data and information from relevant experts (environment, natural resources, industry, and mining), environmental activists and villagers and responsible people in that village. Paytaveh village) was designed and used for use in the final tables of the evaluation method (RIAM method). In the last step, these data and scores, and status classes were used to determine the environmental stability or instability of the mine in a method called the Phillips method.

Results :

As mentioned in the research method, the raw information and data extracted from the opinions of different people were used to score and determine the status of various factors. The results showed that among the 15 factors studied in this study, 7 factors have a negative effect, 5 factors have a neutral effect (ineffective), and 3 factors (all in the category of economic factors) have a positive effect. Meanwhile, socio-cultural factors did not affect, and all four factors in this category were completely neutral and ineffective. By placing the numbers in the said formulas, the final number S in the Phillips formula was determined to be zero. Therefore, according to the classification, the resulting number, zero, is in the instability range. In simpler terms, the calculations show that the mining project is considered unstable and has led to environmental instability.

 The Phillips method was used to investigate and determine the environmental stability or instability due to mining activity in the Paytaveh Bastak area based on information obtained from the RIAM method. The results showed that this project has different effects in the study area. ‌‌‌But in general, the result of the effects indicates the dominance of negative effects over positive effects, and as a result, the environment caused by these effects is unstable. Finally, there is a key issue to consider: the balance between the benefits of mining and its environmental impact is essential to achieving sustainable exploitation of mineral resources. Although the results showed that in the study area, there is no balance between the positive and negative effects of mining activity, but the evaluation and analysis of the views of residents show that the efforts of miners to increase the weight of positive effects (mainly economic: employment of villagers in mining and cooperation with villagers in to carry out the necessary construction and infrastructure activities of the residents) will help increase the satisfaction of the residents and at least in the short term the continuation of the project will be acceptable from the residentschr('39') point of view and will lead to relative relative positive effects in the short term (employment and income for residents). Development and essential infrastructure of residents) will help increase residentschr('39') satisfaction, and at least in the short term, the continuation of the project will be acceptable to residents. It will lead to the relative maintenance of tangible positive effects in the short term (employment and income for residents. However, the use of the word sustainability and especially sustainable development for this activity in general and in this region will not have a proper scientific and logical aspect. In short, mining, as one of the main pillars in many developed and developing countries has always faced many economic, social, and environmental challenges concerning its stakeholders. This has led mining companies to pay more attention to better interact with their stakeholders in recent decades. Therefore, achieving sustainable development has become one of the industrychr('39')s priorities. This key issue will be achieved only if the exploiters try to increase the positive effects, reduce the negative effects of mining and generally pay attention to the demands of the residents of the adjacent areas of the mine, as the main stakeholders, to improve their quality of life and environmental concerns. Perhaps only then will it be appropriate and effective to talk about the environmental sustainability of mining activities in such areas.

Introduction :

Jazmourian basin in southeastern Iran includes parts of Kerman and Sistan, and Baluchestan provinces. This region is one of the sources of dust production in southeastern Iran. The maximum dust emissions in the Sistan region occur in eastern Iran, southwestern Afghanistan, and Pakistan in the summer, and these storms load dust from local scales to regions. Vegetation and its type also play an important role in the severity of dust. There is positive feedback between precipitation and dust emission from the surface; This means that the dust from desert areas reduces rainfall and decreases rainfall, causes the soil to dry out, and further increases dust. In addition to the effect on rainfall, the presence of dust is also effective in its spatial distribution.

 In this study, first, using the optical depth data of the MISR sensors of Terra satellite with a horizontal separation of 0.5 degrees, the monthly and seasonal average optical depth of the aerators in the Jazmourian basin is determined. In order to study the trend of AOD change, the average AOD regions of TODRA satellite MODIS sensor are shown annually in the period 2000 to 2020, and the regression line slope was calculated by age estimation method and Mann-Kendall method with 95% and 99% confidence levels. The amount of vegetation changes in the region has been studied using the annual average of the NDVI index in the Jazmourian region. Since precipitation is one of the factors affecting the occurrence of dust events, the average annual precipitation rates of the TRMM satellite have also been studied. Finally, to investigate the effect of vegetation change on dust, the correlation between the average annual data of AOD and NDVI data and the correlation between the average annual rainfall data and NDVI was calculated to investigate the effect of annual rainfall on vegetation.

Results :

 The monthly average values of the optical depth of air vents were in the period 2000 to 2020. In January, AOD values in the center of the Jazmourian Basin, located on the border of Sistan and Baluchestan and Kerman provinces, are slightly higher than in other parts. From February to July, an increase in AOD is observed in the region so that in large parts of the Jazmourian Basin, the average optical depth of air vents in this month has reached about 0.6. Since August, AOD values have gradually decreased until December; only in the central areas of the basin, small amounts of AOD are observed. As expected, the maximum AOD in this region is observed in summer, and then in spring is in second place. The amount of AOD has decreased significantly in autumn and winter. According to the results, NDVI values were low in years when the mean optical depth of the particles was high. For example, in 2008 and 2012, when AOD values were higher than in other years, the average annual NDVI values decreased. Interestingly, the average annual values of optical particle depth in 2020 and 2017 were lower than in other years, but in the same years, the average annual NDVI values are higher than in neighboring years. The results show that in the years when there is an increase in rainfall in the region, an increase in vegetation and a relative decrease in AOD compared to previous years are also observed. It should be noted that in some years, with increasing rainfall and vegetation, the amount of AOD has not decreased much that it can be said that the amount of AOD, in addition to the activity of local dust sources, is due to dust particles from other areas to the study area and AOD changes only Not due to changes in rainfall and vegetation in the area.

The average monthly light depth values of air vents in the period from 2000 to 2020 show that in January, the AOD values in the center of Jazmourian Basin, located on the border of Sistan and Baluchestan and Kerman provinces, are slightly higher than other sectors. From February to July, an increase in AOD is observed in the region so that in large parts of the Jazmourian Basin, the average optical depth of air vents in this month has reached about 0.6. From August, when small amounts of AOD were observed only in the central areas of the basin, AOD values gradually decreased until December. Also, the average monthly AOD values in the region in the period 2000 to 2020 show that the highest AOD values in July are related to 2003 and 2001, and in June are related to 2008, which is significantly different from other years. Examination of the seasonal average values of the optical depth of air vents in the period under study shows that the maximum amount of AOD in this region is observed in summer and then spring, and AOD values in the autumn and winter seasons have decreased significantly.

Landslides are natural hazards that destroy nature and often cause severe damage to natural resources and loss of life and human property (Intaravichin and Dasananda, 2010; Feyzzadeh et al., 2013). Despite significant advances in risk analysis and landslide risk management, this natural hazard remains a real threat to the lives and property of people in mountainous areas (Getz et al., 2011). Natural factors affecting landslides can be rainfall, lithology, slope, and the like (Talebi and Niazi, 1390). Among the natural factors affecting the occurrence of landslides, we can mention factors such as rainfall, lithology, slope, and the like (Talebi and Niazi, 1390). In general, Iran is considered a high-risk country due to favorable geographical conditions, lack of comprehensive environmental management, and non-compliance with environmental thresholds. Approximately 38 hazards have been identified and recorded in Iran, and due to the multiplicity, diversity, recurrence, and severity of natural hazards and environmental unrest are among the ten most prosperous countries in the world (Mohammadi et al., 2004). Considering landslide hazard zoning map is essential for a proper understanding of its mechanisms in recent research (Sun, 2014).

In order to prepare a landslide susceptibility map using Dempster-Schiffer theory, first, using the landslide database, the General Department of Natural Resources of Mazandaran province, and field studies, landslide points in the region were identified. During the field observations, the accuracy of the collected information was evaluated, and the position of the landslide points was checked using the Global Positioning System (GPS), and 26 new landslides were recorded. A total of 134 slide points were examined. In this research, 12 information layers including altitude map, slope direction, slope degree, slope shape, distance from fault, distance from road, land use, geology, distance from waterway, Slope length or sediment transport index (STI), topographic moisture index (TWI) and vegetation were prepared and classified using ArcMap and ENVI software using 1: 50,000 topographic maps, 1: 100,000 geology, geology and satellite imagery, IRS for 2012. In order to evaluate the Dempster-Schaefer theory in landslide risk analysis, the relative performance curve of the relative efficiency of variables (ROC) is used. ROC curve analysis is used to determine the accuracy and efficiency of the model (Egan, 1975; Soots, 1988; Williams et al., 1999). This curve is one of the most efficient methods in providing diagnostic properties, probability identification, and prediction systems that quantitatively estimate the modelchr('39')s accuracy (Soots, 1988). The area under the ROC curve represents the prediction value of the system by describing its ability to accurately estimate its occurrence events (landslide occurrence) and its non-occurrence events (non-landslide occurrence). Therefore, the area of ​​the curve is used as a measure of the accuracy of the model. In this study, out of 134 slip points, several points were used for modeling, and part of it was used to evaluate the model (with a ratio of about 70 to 30%) (Matthew et al., 2007; Pourghasemi et al., 2009; Constantine et al., 2010).

The study of the slope factor shows that although the highest percentage of landslides is related to the class of 15-30 degrees with 52.127 percent, which is consistent with the views (Moradi et al., 2010). However, the highest weight is related to the class of 5-15 degrees, which can be attributed to road construction and unprincipled constructions that have caused the slope to be cut in the region. No landslides have been observed or recorded in areas with a slope above 50 degrees, which can be due to the rocky outcrop and the lack of soil layer in the high slopes. According to the results of this study, the western and southern slopes with 19.15% and 18.1%, respectively, had the highest percentage of landslides in the region, which with the results of studies (Pour Ghasemi et al., 2009) and (Lee, 2007) corresponds. The study of altitude factors indicates that the altitude class of 1000-500 with 56.38% of landslides, the highest number of landslides, and the altitude class of 0-500 have the highest weight, also, with increasing altitude in the study area, the sensitivity to landslides decreases, which is consistent with the studies of Moradi et al. (2010) and Pourghasemi et al. (2011). At altitudes above 2000 m, no landslides have been observed or recorded, which indicates a decrease in sensitivity to landslides with increasing altitude (Moradi et al., 2010). The highest weight for the geological factor belongs to group 1, which includes deposits and unhardened alluvial deposits of the Quaternary period, while the highest percentage of landslides occurred in the units. The lithology of the Shemshak Formation is located at 37.23%, which is consistent with the views (Naji, 2006), (Shadfar et al., 2008), (Pourghasemi et al., 2011). The study of the linear element of the distance from the waterway has shown that because the highest percentage of landslides occurred at a distance of more than 400 meters at the rate of 31.915%. However, the highest weight in calculations by class is allocated 0-100 meters, which is in accordance with the opinions (Pourghasemi et al., 2009), (Dokota et al., 2013). Investigation of the distance from the road showed that the highest percentage of landslides occurred at a distance of more than 500 meters (30.85%); however, the highest weight in the calculations to the class 0-100 for the distance from the road is allocated which is consistent with the results of studies of Mazouki et al. (2011), Pourghasemi et al. (2009, 2012).

River and river processes are considered the most significant geomorphic systems active on the earth’s surface. Over time, many changes in the morphology and dynamics of the river system can occur. The effects of river adjustment caused by the natural factors require a much longer period to reveal. However, there are few exceptions that natural factors such as river floods, landslides, or earthquakes can induce channel adjustments in a concise time. In contrast, human activities can significantly impact natural processes and trends, resulting in a compressed time scale for river adjustments. Consequently, the flow regime of many rivers has been dramatically altered from their natural flow regime.Redirection, deformation of the canal, destruction of the banks and lands along the river are observed in Qaranqoochay river. Therefore, the purpose of this study is to investigate the effects of Sahand Dam construction on the hydrological conditions of the Qaranqoochay River, determine the geometric components of the river, and investigate the displacement and shape changes of the Qaranqoochay River Canal.

In this research, the topography map with a scale of 1:50000, geology map with a scale of 1:100000, google earth and Landsat images, hydrological data from and field data are used. ENVI 5.3, Arc GIS 10.5, Excel, and SPSS software were also used for image processing and data analysis. To study the hydrological conditions of the study area, the data of the Chapini station were studied using 26 hydrological indices. Then, a paired T-test was used for statistical analysis of indices to study the significance of indices changes and, consequently, the effect of dam construction. The geomorphological parameters of the river and their variations, including bending coefficient and central angle, were measured. The curvature coefficient is one of the few criteria used in river shape segmentation using s = 1/ (y.2), i.e., dividing the valley length by wavelength for each arc (Pittchr('39')s coefficient). It is calculated. The central angle of the arcs on each of the intervals was calculated using the relation A = 180L / Rπ, where A is the central angle, R, of the fitted circle radius (Kornias coefficient). The lateral changes of the canal were investigated using the transect method and calculation of river migration rate. According to the Transect method, lines with distinct distances from both sides of the duct are depicted as baselines. These lines are constant for the periods studied and can be calculated quantitatively for duct movements relative to these lines.

 Results :

According to the results of calculating hydrological indices and T-test analysis, in terms of hydrology Q5, Q10, Q15, minimum flow, maximum flow, and Mode flow, between the two periods before and after the construction of the dam, a significant difference was seen. It can be stated that the construction of Sahand Dam and the changes in the flow by the dam can affect the amount, timing and it affects the duration of upstream and downstream currents. Also, it can provide suitable bedding for intensifying hydrological changes and, subsequently, river morphological changes. Downstream changes include sedimentation and erosion in parts of the river, displacement of meanders, flooring, and wall demolition. The average curvature coefficient had increased from 1.15 in 1995 to 1.18 in 2018, and in 1995, 21.43 of the river patterns were straight (curvature coefficient 1-1/05), but in 2018, there is no direct pattern in the path. The plan of the duct in both periods is sinusoidal (curvature coefficient 1/5-1.05). According to the values ​​of the central angle, in 1995, the studied route from Qaranqoo river was Highly developed as a meandering river (central angle 296-158), and in 2018 it was extended to the meandering river (central angle 158-85), it arrives. With the decrease of the average central angle in 2018, the average radius of the circles has also decreased. The average wavelength and valley length in 2018 compared to 1995, and the decrease in wavelength indicates a decrease in the distance of successive turns.The average rate of river canal migration during the 24 years studied was about 0.143 m per year. The ductchr('39')s maximum amount of transverse displacement in transect one is 0.41 m per year, and the lowest amount of displacement in transect eleven is 0.022 m per year.

Discussion & Conclusions :

In general, the changes in the plan of the Qaranqoo river in the studied time and place period have been in the form of expansion of existing meanders, shifting of the river course, and formation of small meanders. Formation and morphological changes of the Qaranqoo river in the studied time and place period are mostly influenced by hydrological processes caused by dam construction (significant reduction of runoff in the river and accumulation of sediment load in the bed path) and lithological conditions of the bed and side. Of the river. Also, human beings have changed the pattern of the Qaranqoo canal in the studied area by harvesting river materials, encroaching on the river area in the form of land-use change, farming in river lands, and pumping water for agricultural lands along the rivers, construction of bridges.

The ability of soil to provide products in the ecosystem, protect soil and water and perform its environmental functions reflects the quality and health of the soil. Soil health is an index for assessing soil functions such as crop production and growth of microorganisms. Soil health is affected by soilchr('39')s physical, chemical, and biological properties, and its integrated evaluation needs to consider the collective effect of these characteristics. In this study, to present the cumulative soil health index, an integrated quality index (IQI) and Nemero quality index (NQI) were used. These indices are designed initially to assess soil quality, but they are used to assess soil health in this study. To determine these Indices, the most important characteristics affecting soil health were determined by the PCA method.

In this study, 72 soil samples were taken from 208 hectares in the Khaneghah Namin area of Ardabil province, which included 19 samples of agricultural lands and 53 samples of rangelands. In each soil sample, 16 physical, chemical, and biological properties of soil (pH, EC, organic carbon, percentage of lime, percentage of sand, silt and clay, porosity, bulk density, the population of soil microorganisms, basic microbial respiration, microbial respiration Substrate stimulated, microbial biomass carbon, microbial biomass nitrogen, biomass carbon to organic carbon ratio and metabolic fraction) were determined as total data set (TDS). Among these properties, five factors were obtained as minimum data set (MDS) using PCA. Then, soil health indices were calculated based on the two methods of the integrated quality index (IQI) and Nemero quality index (NQI), and using two TDS and MDS data sets. The significant correlation of indices calculated by TDS with MDS (Correlation of IQITDS with IQIMDS and NQITDS with NQIMDS) confirmed the efficiency of selected MDS to determine the soil health indices. Also, the difference of soil health indices between agricultural and rangelands was compared by a non-paired t-test. 

Results :

Based on PCA results, five biological and physical soil properties were selected as the minimum data set. These properties include basal soil respiration, soil biomass carbon, soil biomass nitrogen, bulk density, and total soil porosity as the most important characteristics affecting soil health. In IQI index for a combination of soil properties as an integrated index, weighted scores of properties calculated. For scoring the soil properties used from fuzzy membership functions that scoring between 0-1. The commonality of properties is divided by the sum of commonalities in a data set to weighting the properties. The results showed that IQITDS and IQIMDS soil health indices rated the regionchr('39')s soils as grade II, while NQITDS and NQIMDS indices ranked the soils as grade IV. A significant correlation was obtained between the indicators calculated with TDS and MDS in the region and rangeland and agricultural land use. The average IQITDS, IQIMDS, NQITDS, and NQIMDS indices in the rangeland were 0.71, 0.67, 0.03, and 0.082, respectively. The indices in agricultural fields were 0.66, 0.66, 0.027, and 0.08, respectively. The mean comparison between two land-use shows that IQITDS and NQITDS have a significant difference, and IQIMDS and NQIMDS do not have a significant difference. These results show that rangelands have significantly more soil health in comparison to agricultural lands. Also, these results show that the integrated quality index (IQI) is more suitable for evaluating soil health in comparison to nemero quality index (NQI). 

This study shows that the PCA method had efficient in selecting the most important characteristics that affect soil health. Qi et al. (2009) and Shahab et al. (2018) confirmed the PCA efficiency in MDS selection. It was also observed that the use of soil biological properties in determining the cumulative indices of IQI and NQI could lead to better modeling of soil quality and health so that most of the characteristics selected as MDS by PCA are the biological characteristics. Zhou et al. (2020) reported that the use of soil biological properties as indicators of soil health could be used to detect soil degradation. Comparison of soil health between agricultural and rangeland showed that cumulative indicators with TDS data could provide a better index for evaluating land use impact on soil health.

Gully erosion is the most obvious form of soil erosion, which leads to reduced production capacity, significant soil losses, and the production of large amounts of sediment and restricting land use. It can be a severe risk to agricultural areas and villageschr('39') roads and structures. Due to the lack of information on soil erosion and sediment production in many watersheds of the country, the use of new technologies such as remote sensing and GIS is necessary so that the use of this technology can be a valuable source of information to understand the trend of Gully changes. The study area is located in the west of Bandar-e-Lengeh city in the Hormozgan provinc. The approximate geographic coordinat is 54° 19¢ 11² to  54° 30¢ 40 longitudes and 26° 40¢ 57² to 26° 56¢ 04² latitude. The study area is mainly formed by sedimentary rocks belonging to the Mesozoic period (Fars group formations) with low permeability. This factor, along with the low rainfall and very high intensity, has destructive effects on natural resource ecosystems.

This research is focused on gully erosion mapping and monitoring at multiple spatial scales using multi-source Arial photo and remote sensing data for gullies extend in the past decades. Aerial photos of 1957, Landsat satellite images of 1994, 1984, 2004, and GeoEye satellite images for 2014 and 2016 have been used to study the long-term changes in the growth of Gully erosion. Image visual interpretation with field verification was employed to map the geometric gully features and evaluate the growth of the gully in the last 60 years.

The results showed the gully areas increased from 112 hectares to 206 hectares from 1984 to 2004. The results also show that during the period 2004 to 2014, the gully areas increased from 206 hectares to 316 hectares and 370 hectares in 2014 to 2016.50 gullies were studied to investigate the longitudinal growth of ditches in the study area. The results show the annual rate of gullieschr('39') longitudinal growth is 4.9 meters for1984-2004 and 6.8 and 2.95 meters for 2004 to 2012 and 2012 to 2016 periods, respectively.

The long-term growth rate of gullies in the study area (1975-2016) is an average of 5.2 meters per year, which is very high comparing to researches conducted in the world and Iran. For example, in their study, Ghezelsofloo et al. (2018) estimated the annual erosion rate of 0.99 m for the Shurdreh catchment, and Ahmadi et al. (2007) estimated the annual growth rate of 0.206 m for the Hablehroud basin.In other studies, conducted by Rostamizad et al. (2015), the annual growth rate of 0.85 m for the city of Darhshahr, Tavakoli Rad et al. (2014) 1.29 m in the Samal Basin of Bushehr, Nazari Samani et al. (2014), growth 1.3 meters for the Kore Dareh catchment.In other countries, Malik (2007) estimated the average erosion rate of the small gully at 0.63 m per year. Millington et al. (2013) also estimated the average rate of gully erosion on slopes from 0.21 to 0.51 m per year on the southern plateau of Poland.In another study, the growth rate of the ditch was calculated by Pellikka et al. (2005) for the Tiata hills of Kenya as 0.1 to 0.7 m per year.In addition, the research results show that the High sensitivity of Fars Group formations to erosion, arid climate, weakness and degradation of vegetation and very high intensity of 24-hour rainfall in the study area, lack of flood management are main reasons for the high longitudinal growth of gully in the study area. Other reasons are human manipulation in flood diversion and concentration, a very high percentage of soil silt, release of rainfed lands and the existence of a wide network of local access roads. The resuls are consistent with the results of Karimi et al. (2007), Mohammad Ebrahimi et al. (2017), Asghari Sarskanrood (2017), Besharati et al. (2018).

One of the environmental crises that have caused a lot of concern in recent years is the pollution caused by wind erosion in arid and semi-arid regions, especially in Iran. Recently, it has been reported that about 26% of changes in atmospheric dust concentrations occurred due to changes in the drought index resulting from changes in precipitation to evapotranspiration. Increasing air pollutants concentrations, especially dust particles, had negative effects on agricultural production, human health, and the environment. Therefore, temporal and spatial analysis and continuous monitoring of these events in different regions, especially in arid and semi-arid regions, are of great importance. Accordingly, the main purpose of this study is to analyze the trend of dust pollution caused by wind erosion at different time scales and to investigate the spatial distribution of dust particles in Fars province, southwestern Iran, during the years 2000 to 2018.

In this study, using the pollution of dust storm index (PDSI), the pollution caused by wind erosion events in eleven synoptic stations located in Fars province was calculated. The frequency of local, moderate, and severe dust events was used to calculate this index. Then, the Mann-Kendall test was used to analyze the trend of monthly, seasonal, and annual changes. The trend of changes was calculated separately for the study stations. Furthermore, the map of spatial changes of air pollution in Fars province from 2000 to 2018 was prepared using the reverse distance weighting method. Finally, areas more sensitive to wind erosion were identified based on the generated maps using this method.

 Results :

Analyzing the trend of monthly changes in PDSI using the Mann-Kendall test showed that the most incremental and significant changes in dust pollution occurred in April, May, and February in Fasa, Shiraz, Dorodzan, and Zarghan stations. Meanwhile, the trend of decreasing and significant changes in PDSI has occurred mainly in Lar and Darab stations and from May to October. The results of the seasonal change trend showed that regardless of the confidence level, more than 70% of the study stations have experienced an upward trend in spring, summer, and autumn. In winter, all stations except Darab station have experienced increasing changes in air pollution. On an annual scale, the trend of decreasing changes was observed only in Darab and Lar stations, while the trend of changes in other stations of Fars province was increasing. The pattern of the spatial distribution of dust particles in Fars province showed that in 2003 and 2005, more than two-thirds of Fars province and mainly the central to southeast areas were faced with high dust concentrations. In recent years, and especially in 2017 and 2018, the distribution of dust particles has changed. In recent years, residents of the central to southwestern Fars province have suffered more from reduced air quality due to increased concentrations of atmospheric dust particles.

The growing trend of dust pollution caused by wind erosion events in recent decades has raised major concerns at various regional, national and global levels. Therefore, it is necessary to understand the trend of temporal and spatial changes of pollution caused by these events to reduce their adverse consequences in different regions. Based on the findings of this study, the trend of temporal changes in dust events and the pattern of dust particle distribution in the southern half of Fars province is also worrying because, in most cities of Fars province, an increasing trend in air pollution was observed. In addition, according to PDSI maps, a large part of the province is exposed to the dangers of dust storms and air pollution. Considering that PDSI is calculated based on the frequency of local to severe events, it can be concluded that the frequency of wind erosion events has increased in most cities of Fars province. In other words, these findings indicate the intensification of dust events and pollution caused by it in this province. Our results also showed that in the long-term (2000-2018), the southern half of Fars province, compared to the northern half, was more sensitive to dust events and, as a result, played a major role in dust production across the province. One of the reasons is drying the bed of Bakhtegan-Tashk, Maharloo, and Parishan wetlands, located in the southern half of the province, and have acted as dust generating sources, especially in recent years. As a whole, the results of this study can help managers and planners to prioritize managerial and executive measures to combat the risk of desertification and reduce the adverse impacts of dust storms in dusty areas.