منصور جهان تیغ

The aim of this study was to determine properties of soil Citrullus colocynthis habitat. First implement the distribution status of this plant in Nimroz city and by establishing two transects, each with a length of 250 meters and at a distance of 50 meters, a plot of 3× 3 meters was determined according to the type of cover. Also the characteristics of cover percentage, bare soil and litter were determined. forty soil samples were taken from habitats of this plant and control areas from a depth of 0-50 cm and analyzed some soil properties. T-test and principal component analysis (PCA) method were used to compare the soil properties and to determine the factors affecting the establishment of plant species. Results showed that there is a significant difference between the mean of acidity, carbon, total calcium and magnesium, sodium, sodium adsorption ratio, soluble sodium, total cations, absorbed phosphorus and potassium, clay, silt and sand in the two studied areas. But between other data, it is not statistically significant. The multivariate analysis indicate that the plant tends to settle in soils with higher organic matter, phosphorus, potassium and clay and the variables of sodium content, sodium uptake ratio, total cations and sand percentage are the most important obstacles to the establishment of this plant in study area. Conclusion the soil characteristics of this plant, its ecological needs are low in the harsh ecological conditions of the region and can be adapted to poor soils.

Today, water security is one of the important limitations of development, especially in dry and desert areas. Because these areas not only have low rainfall, but also this low rainfall is not properly distributed. Despite the increase in irrigation efficiency in some agricultural methods, the limitation of freshwater resources in some areas makes it necessary to use salt water in agriculture. However, the use of these water sources has negative effects on the soil and the environment. So the salinity of soil and irrigation water reduces crop yield and puts soil resources at serious risk. It is possible to increase the crop yield and control soil erosion by using the appropriate irrigation method. The problem of salinity in plants is due to the accumulation of excessive amounts of sodium chloride, which is widely spread in coastal areas, soils of dry areas, and fertile lands. Studies have shown that the use of saline water, especially in conditions of equal fertilization between treatments, often reduces the absorption of important nutrients such as nitrogen due to the existence of a significant relationship between the absorption of water and nutrients. Research in the north of Golestan province showed that salinity causes a significant decrease in plant biomass. The effect of salinity stress on the accumulation of sodium, potassium, and chlorine in the plant was significant and the highest amount of ions was accumulated in the leaves. The plant's root system is selective in absorbing and transferring sodium to its aerial parts.

To do this research, first, by selecting 36 experimental units, holes with a diameter of 50 cm and a depth of 60 cm were dug in the center of each one, and then the treatments were prepared. This research is in the form of treatments consisting of irrigation factor (clay and drip irrigation method), salinity level (salinity up to 1200, salinity up to 2200, and salinity up to 3200 µmhos cm-2), and plant (Rose and Hibiscus sabdariffa) in three repetitions and it was done factorial randomized complete blocks design. Three water sources each with a capacity of 200 liters were placed at a height of less than two meters from the ground. Rose plant was prepared in the form of potted seedlings and Hibiscus sabdariffa seeds were planted in the greenhouse and after about two weeks in March, it was transferred to the field. The growth height of the plants, as well as the crown, the diameter of the plant stem, and the number of their branches in the growing season were measured. Also, three soil samples were collected and their characteristics of salinity, acidity, and texture were measured. In order to analyze the data, the statistical method of analysis of variance (ANOVA) and the least significant difference (LSD) test were used to compare the average of the studied indicators using MSTAT-C software and SPSS software.

The results of variance analysis of some growth traits of the studied species showed that seedling height and stem diameter were affected by different levels of salinity and the values ​​of this plant characteristic showed a statistically significant difference. The reason for the decrease in plant growth in a plant that is irrigated with more salinity is that the presence of salt in the soil exceeds the tolerance threshold of the plant, and as a result, the accumulation of excess salt in the root zone is a limiting factor for plant growth. According to the results of the effect of irrigation methods, as well as the interaction effect of salinity and irrigation method on the aforementioned indicators, there was no statistically significant difference. The interaction effect of plant and water salinity levels on the values ​​of these variables was significant. The comparison of the average data showed that the height of the studied species was significantly increased by using the clay irrigation method. The maximum diameter of the stem was also measured in the clay irrigation method, which was associated with an increase of 1.7\% compared to the drip irrigation method. Also, the results show that the highest values ​​of the studied variables are related to the rose flower plant, which is 1.7 and 3 times more than the sour tea plant, respectively. Clay irrigation causes water to be transferred to the root area of ​​the plant, which improves the performance and growth of the plant by providing the required moisture around the root. In other words, the way to distribution soil moisture in clay irrigation takes place in the form of percolation and uniformly around the root of the plant, which causes the moisture to be placed directly around the root area and thus affects the growth of the plant. In addition, the canopy data and the number of branches showed that there is no significant difference between them.

This research tested the effect of different levels of water salinity and clay and drip irrigation on the establishment of plants in the Sistan plain, considering the existence of a water shortage crisis in the region, in order to use saline water on two plants, rose and Hibiscus sabdariffa. The results showed that clay irrigation performance was better than drip irrigation at all salinity levels. Because in the drip irrigation method, with the occurrence of drought stress, it reduces plant growth compared to the clay irrigation method. In addition, in the drip irrigation method, water is placed on the soil surface and deep penetration is limited, and as a result, the increase in humidity in the subsurface layers is less. In the clay irrigation method, due to deep penetration and uniform distribution of moisture in the soil profile, the amount of moisture stored in the soil increases.

  Wind erosion is affected by climate change and several droughts have caused environmental degradation in arid regions. This process causes sand and dust storm (SDS) phenomenon which is one of the most important challenges in fragile areas. This phenomenon is harmful for human health and causes socio-economic problems. Over the past two decades, SDS have been increasing in Iran, particularly in the south-east of the country. Therefore, in order to manage this environmental phenomenon in arid areas, it is an urgent need to identify the dust storm sources. The changes of factors such as vegetation, soil moisture, slope, land temperature, and geological units have effective roles in the occurrence of dust storms. So, investigating the changes in these factors is an effective solution to identify dust storm sources. In this regard, using remote sensing data is one of the effective methods for the detection and mapping of dust storms resource, which combined with field methods, provides a coherent approach to manage and control this phenomenon. This study aimed to identify dust sources and storms in the southeast of Iran with emphasis on the Sistan dust storm by using field work and remote sensing data.

The study area is located in the south east of Iran and contains some of the border areas of Iran and Afghanistan (including some parts of the south Khorasan and Sistan and Baluchestan province in Iran as well as Farah and Nimroz province in Afghanistan with coordinates of 60˚ 16′ - 61˚ 36′ east longitude and 29˚ 8′ - 32˚ 32′ north latitude). In north of the study area, the mountainous and low-altitude areas are intertwined but the southern area is mostly flat and lacks topography and natural features. The most important characteristics of this area is 120-day winds, which sometimes reach speeds of more than 120 kilometers per hour and is accompanied by high intensity of sand and dust storms. In this study, to identify dust storm sources, the combination of remote sensing, field study and wind analysis methods are used. To achieve this purpose, at first effective factors in the occurrence of dust storms such as vegetation, soil moisture, slope, land temperature, and geological units were prepared. In this regard, by using Modis satellite images, map of vegetation, soil moisture and land temperature were prepared by applying Soil Adjusted Vegetation Index (SAVI), integrating temperature vegetation dryness index (TVDI) and Land surface temperature (LST), respectively. Also slope map (using Aster satellite) and geological units were prepared. In the next stage, the fuzzy logic method was employed to combine layers and prepare the map of dust storms source, which is assessed by an error matrix and available dust source map. Detection of sand dust storms were performed by using BTD dust detection indicator. For winds analysis, we used WRplot view 8 Software. In the field study, several dust storms sources were determined and their characteristics were recorded.

    The results showed that the ranges of SAVI index are + 0.6 to -1 and the highest amount of this index coordinate with highest soil moisture (TVDI) and the lowest land surface temperature (LST) area. This area is mostly related to rangeland, combination of wetland-rangeland, hand-planted forests and agricultural lands. The amount of SAVI index and soil moisture reaches its minimum value in the salt marsh lands, abandoned agricultural lands, desert areas and degraded rangeland. By merging the layers and preparing the map of dust storm sources, it was found that the critical dust storms resources coordinate with high land surface temperature and low vegetation and soil moisture areas. In addition, the highest dust source area is in the slopes of 0 to 4 % with geological units such as playa deposits, eolian deposits, alluvium sediment and wet playa deposit. According to the results, the incoming dust storms into the study area come from the east and southeast of south Khorasan province in Iran and the southwest of Farah province in Afghanistan.

  In this study by using effective factors including vegetation, soil moisture, land surface temperature, slope and geological units, the sources of dust production were identified. According to the results, poor vegetation and low soil moisture in flat areas with sensitive formations are the key factors to create dust storm resources in the study area. Also, the most important active hot-spot areas for dust storm is concentrated in the southwest of Afghanistan and north of sistan region (dry lake bed of Hamoon). Therefore, it can be concluded that using satellite images and the studied factors, the dust sources can be properly identified. Furthermore, by using Time series images of modis and the updated dust source maps, a coherent approach can be provided in order to manage and control this phenomenon.

The excessive use of water and soil resources, especially in arid and semi-arid regions, causes increased soil erosion, followed by the appearance of destructive floods, the emergence of dust, and intensifying the phenomenon of desertification. Therefore, in order to prevent the environmental problems of these areas, there is a need for efficient management of their water and soil resources. The rainwater catchment systems are one of the strong points of dry and desert areas, which have a high ability to develop these areas. This study investigated the effect of rain catchment systems on the physical and chemical characteristics of rainwater catchment systems soil in the Mil Nadir area of Sistan. For this purpose, six soil samples were taken from the rainwater catchment systems and the control area and their physical and chemical properties were measured. The results of this study showed that there is a significant difference of 1% between the average percentage of clay, silt, and sand in the soil of the rainwater catchment systems areas compared to the control area (P<0.01). With the increase in the percentage of clay and silt, the soil texture from class Loamy-sandy in the control area was changed to loamy class in rainwater catchment systems, which caused a 28% increase in soil moisture compared to the control area. In the examination of soil chemical properties, the findings indicate that the amount of acidity, electrical conductivity, sodium, and sodium absorption ratio significantly (P<0.01) in the soil of rainwater catchment systems decreased, but the amount of organic matter, nitrogen, and potassium increased. The effect of rain catchment surface systems has improved the physico-chemical properties of the soil, due to the existing environmental crises and the acceleration of the desertification process in this region. The use of these catchment systems in the Sistan Region provides suitable conditions for improvement. It provides ecological and environmental protection of these areas.

land degradation and desertification in arid areas are the most important environmental challenges in the world. This process due to the lack of precipitation and the occurrence of drought, while the unreasonable exploitation of natural and agricultural areas with increasing demand to provide human food needs, affects various environmental and socio-economic dimensions. So, the continuation of this condition during recent years with the destruction of vegetation and soil, wind and water erosion, soil salinity, soil compaction, and declining groundwater aquifers have significant consequences for the production of agricultural products and biodiversity in an arid region. Since the pattern and dimensions of vegetation changes are the most important factors in detecting land degradation, monitoring the vegetation changes is the best approach to analyzing land degrading and desertification trends in an arid region. Therefore, according to the capabilities of remote sensing data due to the wide coverage and multi-timed,  the use of satellite imagery to monitor vegetation changes by using vegetation index is one of the best methods that developed in recent years. Moreover, concurrent access to high spatial and temporal resolution imageries is one of the important factors that affect the monitoring of vegetation changes. To achieve this goal, It needs to incorporate different satellites with high spatial (e.g., Landsat satellite) and temporal (e.g., MODIS satellite) images. The purpose of this study is the monitoring vegetation changes using daily Landsat simulated images at 30 m Spatial Resolution in three years of wet, normal, and drought in the Nimroze area.

 The study area is located in the north of the Sistan and Baluchistan provinces. Low precipitation (50 mm), high temperature (48 oC), high evaporation (5 m), and 120-day winds are among the specific climatic conditions that characterize this region. In this study, at first, the hydrological drought status of the Hirmand River was investigated. Using the Hydrostats package in R software, the amount of threshold of flood by running the related codes (by running codes such: daily.cv, ann.cv, high. spell, and low. spell) during the statistical period of study (29 years) was calculated. To determine wet, normal, and drought years calculated the length of periods that flood is higher (high. spell. lengths) and lower (low. spell. lengths) than the threshold. To increase the accuracy of monitoring vegetation changes, it needs to incorporate different satellites with high spatial (e.g., Landsat) and temporal (e.g., MODIS) images. To achieve this purpose, in this study, the Enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM) was evaluated with actual satellite data (OLI, ETM+, TM image). For this purpose at first, pre-processing (geometric, radiometric, and atmospheric correction) was performed on satellite images, and by using the ESTRFM model, simulated daily Landsat images at 30 m spatial resolution for wet, normal, and drought years. In-field operations from different plant communities by GPS were sampled. Comparing filed data with the Normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI), the vegetation index that had the highest correlation with field data was selected. To investigate vegetation changes, using the vegetation index (the vegetation index with high correlation), the map of vegetation for each year was prepared (wet, normal, and drought years). After the classification maps of vegetation, by comparison, approach (cross tab), the map of vegetation changes was extracted.

 The results of analyzing wet and dry periods showed that, flood volume in dry years compare to normal and wet years decreased 31 and 82 percentages, respectively. To incorporation MODIS and Landsat (OLI, ETM+, TM) Images, using enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM), finding indicate that this model improves the accuracy of predicted fine-resolution reflectance and preserves spatial details for heterogeneous landscapes too. So that the mean coefficient of determination (R2) of blue, green, red and near-infrared estimation bands with actual satellite images data is 0.91, 0.89, 0.92 and 0.91 respectively. Also the average Root-Mean-Square Error (RMSE) in four bands obtained 0.01, 0.027, 0.028 and 0.031 successively. Comparing the obtained field data with the Normalized difference vegetation index (NDVI) and the soil adjusted vegetation index (SAVI), indicate that SAVI index has the highest correlation (R2= 87) with vegetation of study region. By calculate the regression model (using SAVI and field data) and classify the vegetation maps of wet, normal and drought years, 6 class obtained (class1=0-10%, class2=20-10%, class3=20-30%, class4=40-50%, class5=60-80% and class6=>80%). The results of investigation vegetation changes indicate that during the drought period 70% of study area has less than 10% vegetation (equal to 138176.3 hectares) and during normal and wet years by increasing vegetation, this area decreased by 30 and 48% respectively (equal to 66269.98 and 50559.7 hectares, respectively). According to the results during the study period, the most vegetation changes is relate to conversion of class 1 to class 2 (equivalent to 48.5%). moreover 18 and 27% of vegetation changes relate to class 1 and 2 to class 4 and 5 respectively (equal to 16284.26 and 11471.88 hectares, respectively). Also the finding indicates that the most vegetation changes occurrence in wetland-forest (28%), forest-rangeland (21%) and poor rangeland (19%) land uses respectively. Field study also showed that, the most important plant species that grows in this land-use such as the results of analyzing wet and dry periods showed that flood volume in dry years compare to normal and wet years decreased by 31 and 82 percent, respectively. To incorporation MODIS and Landsat (OLI, ETM+, TM) Images, using enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM), the finding indicates that this model improves the accuracy of predicted fine-resolution reflectance and preserves spatial details for heterogeneous landscapes too. So that the mean coefficient of determination (R2) of blue, green, red, and near-infrared estimation bands with actual satellite images data is 0.91, 0.89, 0.92, and 0.91 respectively. Also, the average Root-Mean-Square Error (RMSE) in four bands obtained 0.01, 0.027, 0.028, and 0.031 successively. Comparing the obtained field data with the Normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI), indicate that the SAVI index has the highest correlation (R2=87) with the vegetation of the study region. By calculating the regression model (using SAVI and field data) and classifying the vegetation maps of wet, normal, and drought years, 6 classes obtained (class1=0-10%, class2=20-10%, class3=20-30%, class 4=40-50%, class5=60-80% and class6=>80%). The results of the investigation of vegetation changes indicate that during the drought period, 70% of the study area has less than 10% vegetation (equal to 138176.3 hectares) and during normal and wet years by increasing vegetation, this area decreased by 30 and 48% respectively (equal to 66269.98 and 50559.7 hectares, respectively). According to the results during the study period, most vegetation changes are related to the conversion of class 1 to class 2 (equivalent to 48.5%). moreover, 18 and 27% of vegetation changes relate to class 1 and 2 to class 4 and 5 respectively (equal to 16284.26 and 11471.88 hectares, respectively). Also, the finding indicates that the most vegetation changes occur in wetland-forest (28%), forest-rangeland (21%), and poor rangeland (19%) land use respectively. The field study also showed that the most important plant species that grow in this land use such as Aeluropus littoralis, Chenopodiace sp, Tamarix aphylla, Haloxylon aphylum are adaptive to climatic regime in study area.

 In this research for the first time in the Nimroz region of Sistan Vegetation changes were studied using Landsat simulated images during periods of low water, normal, and high water years. Due to low rainfall and harsh climate in the study area, floods in the Helmand River are the only source of water supply required in the study area. The results of analyzing wet and dry periods showed that flood volume in dry years compared to normal and wet years has decreased by 31 and 82, respectively. According to the reduction of flood volume during a drought year, 70% of the study area has poor vegetation and during normal and wet years, providing plants with water needs and increasing vegetation, this area had decreased by 30% and 48%, respectively. According to the results of this study, change in hydrological conditions of the Hirmand River has a significant role in vegetation changes in the study area by using simulated images with high spatial and temporal resolution can improve the accuracy of monitoring vegetation changes to control and management the desertification in Sistan area.

With rapid population growth and increasing demand for food, water shortage is one of the challenges of development in countries, because more than 98% of the water on the earth is salt water. In addition, the use of some fresh water sources is also limited. Such a situation will worsen with time. This limitation is more in dry and desert areas that have little rainfall and their distribution is not suitable. The country of Iran, which is located on a dry belt and its rainfall is less than a third of the global amount, is one of those areas that is facing a lot of water stress. Due to the lack of rainfall in the country and, on the other hand, the lack of scientific use of the country's natural and agricultural areas, the ground has been laid for the destruction of natural ecosystems. Accordingly, due to the limited supply of fresh water for agricultural purposes in the world, especially in dry areas, saline water is widely used to irrigate crops to provide the water needed by plants. Due to the use of saline water with a high concentration of salt, especially sodium salt in the soil, it causes a decrease in production efficiency and destruction of the physical and chemical properties of the soil. Since most of the water resources are consumed in the agricultural sector, an appropriate irrigation pattern should be used to prevent soil degradation and erosion in addition to increasing crop yields. Clay pot irrigation is one of the methods that has a better performance than other irrigation methods such as surface and drip type. This type of irrigation is suitable in dry areas that have high evaporation and transpiration and are associated with water crisis.

In order to carry out this research, first, 36 holes with a depth of 60 cm and a diameter of 50 cm were dug, and in 18 holes, a clay pot was placed with a height of 40 cm and a diameter of 5 cm, and 18 holes were selected as control and without clay pot. Three soil samples were taken from a depth of 50 cm at the beginning and at the end of the research period. Soil changes were made by irrigation with saline water and the characteristics of pH, EC, Na, SAR, organic matter, P, K, Ca, Mg and soil texture were measured. Considering that three types of water with different salinity (1200, 2200 and 3200 umho/cm) were used, three sources of water each with a volume of 200 liters were placed beside the location of implementation. By using the variety of saline water that existed in this area, bringing the EC of water to the level required for the research was done in the laboratory and stored in the relevant water sources. Cultivation of two plants, Rosa damascena and Hibiscus sabdariffa, was tested. Soil moisture (by weight) was measured monthly at a depth of 60 cm.

Examining the pH of the soil samples shows that there is not much difference in the value of this characteristic of the soil of the research area, such that the range of this characteristic varied between 8-8.4. Changes in the EC of the investigated area at the beginning of the project fluctuated between 4.4 and 5.2 mg/liter. After the implementation of the saline water plan, it has been affected, such that the range of this feature has been varying between 16.5-9.7 mg/liter. Measuring the amount of Na at the time of starting the work showed that the range of changes fluctuated between 43.3-43.85 mg/liter. Total Ca and K were measured as 19.7-24.2 mg/liter, while the amount of this feature changed between 26.5-18.4 mg/liter after the completion of the project. The amount of SAR of soil samples at the beginning of the implementation of the project was between 13-3-17, but after the implementation of the project, this range changed between 12-7-18-4. The range of total cations of the soil samples collected at the beginning of the research varied between 43.5-43.5 mg/liter. But after the end of the project, this range changed to 103.5-72.8 mg/liter. Examining the texture of the soil samples at the start of the project showed that the range of clay changes varied between 14-15%, but after the completion of the research, it changed between 10-14%. The amount of silt in the soil samples at the time of starting the project was 43-47%, while this value changed to 44-48% in the samples after the end of the plan. Examining the amount of sand in the soil samples at the beginning of the research showed that the range of changes was between 42-39%, which did not change at the end of the project.

In this research, the effect of two irrigation methods with saline water on soil moisture and physical and chemical properties was investigated. The results showed that compared to the average of all characteristics, clay pot irrigation performance was better. The work process in this irrigation method is such that the clay pot plays the role of a filter and suitable water is provided for the plant. In this type of irrigation, the transfer of water is limited to the area of ​​the plant's roots, which causes an increase in soil moisture in this area, and improves the plant's performance. In other words, the distribution of moisture in the soil during percolation clay irrigation is such that the water enters the root area of ​​the plant uniformly, which, in addition to meeting the water requirement, also reduces the temperature of the soil. But in drip irrigation, moisture is placed on the soil surface, after which the moisture spreads horizontally on the soil surface and the water does not penetrate deep into the soil. This situation causes evaporation and transpiration to increase and plant roots face water stress. Also, soil solutes cause the soil to become salty through evaporation. In addition, water salinity also increases the intensity of soil salinity, which leads to soil degradation and erosion. Therefore, for the continuation of exploitation in dry and desert areas, it is necessary to use the appropriate method of irrigation in order to sustainably exploit the land without harming its ecosystem components, including the soil. Therefore, according to the existing methods of irrigation, the clay pot type is more important than other types of methods. It can thus be concluded that due to the lack of fresh water resources in Sistan and the limited flow of water from Afghanistan and the existence of subsurface saline water sources, it is necessary to use them, that the use of clay irrigation method has a positive effect on the vegetation and the improvement of the environmental situation and the continuation of exploitation.

To conduct this research, first by preparing the land use map using Landsat 8 OLI sensor images and its combination with geological map, homogeneous units were determined and sampling was done in randomly-systematically in the representative areas of each plant community. Sampling was done along 3 transects of 500m which were vertical, in each site. In each transect placed 10 plots of 3×3m2 at a distance of 50 meters from each other And characteristics related to any plant including vegetative form, scientific name, genus, canopy percentage were harvested. Also, 48 soil samples were taken from a depth of 0-20cm and properties such as soil texture, organic matter, salinity, pH and adsorption ratio sodium were measured. To classification plant communities and investigate the relationships between these communities and soil properties using cluster analysis and principal components analysis respectively in Rstudio software. According to the cluster analysis results, four plant communities were identified and tamarix stricta and Suaeda fruticosa plant species with shrub-shrub vegetative form had the highest frequency with 37.2% and 26.5%, respectively. Results of ANOVA indicated that there were significant differences between some soil properties in identified plant communities. There is also a relationship between the plant communities distribution and environmental factors (p<0.05). The results also showed that the most important factors affecting the establishment and distribution of plant communities in the study area are the percentage of sand, electrical conductivity, sodium absorption ratio and percentage of organic matter

The objective of the study was to compare the desert environments soil physical and chemical characteristics with different vegetation types. This study has done in southwestern of Sistan region (Tasoki and Torsh Ab).
Study

The study areas were distinguished based on geologic maps in scales of 1:50,000 and field observations, and global positioning system (GPS). Four soil samples were taken from the 0-45 cm depth at each location and analyzed for pH, EC, organic matter, organic carbon, nitrogen, CaCO3, ESP, potassium, moisture, sodium, phosphorus, magnesium, calcium, sodium adsorption ratio, chlorine and texture. Dates were analyzed using SPSS software. 

The data indicated that there are no statistically significant differences between soil properties including: pH, nitrogen, phosphorus, moisture, magnesium, and silt, at the 0.05 levels (p> 0.05). But, there are statistically significant differences between soil properties including: organic matter, organic carbon, CaCO3, ESP, potassium, sodium adsorption ratio, calcium, clay and sand were statistically significant at the 0.05 levels (p< 0.01).

Concluded that the study area soil no limits to incrase of vegetation cover. The studies concluded that there were no soil limite for incrase of vegetation cover in study area.

Shortage of rainfall and drought are among the factors affecting the water shortage crisis in arid regions due to the high rate of evaporation in these areas, while reducing the amount of water productivity, it reduces soil moisture. Therefore, the application of conservation methods by reducing the rate of evaporation and maintaining soil moisture in addition to improving plant growth and yield increases water productivity. The aim of this study was investigation of the effect of sand mulch and nano-clay in buried clay pot irrigation on temperature and humidity changes in one of the wind erosion centers of Sistan region. For this purpose, wind sediments accumulated in Sistan plain as well as flood sediments of Helmand riverbed (sediments transported during floods entering from Afghanistan) were sampled. By determining the particle size of sediment samples, the largest particle size of wind sediments was separated to prepare a sandy cover using a sieve. To prepare clay nanoparticles, Flood sediments were also pulverized using ball mill by examining the particle size and determining the main elements (using the XRF method). By preparing treatments including sand cover, nano-clay and control by installing thermometers and probes at depths of 10, 30 and 50 cm Soil temperature and humidity were measured (using TDR) for a period of 186 days. Also, at the end of the test period to evaluate soil stability indices by sampling from different depths, the mean weight diameter (MWD) and geometric mean index (GMD) of aggregate diameter were measured based on dry sieving method. The results showed that there was significant different at 5% level on soil moisture and temperature distribution between treatments. In depth 10 cm, the highest amount of retained moisture were measured in sand mulch treatment (1.2 and 1.4 times retains moisture compared to nano-clay and witness treatments, respectively). The highest amount of retained moisture in depth 30 and 50 cm is related to nano-clay treatments (45 and 68% more maintain compared to sand mulch and witness treatments, respectively). The results also show that the highest and the lowest amount of soil temperature at different depths related to witness and sand mulch treatment respectively. Mulch cover by shaping temperature equilibrium in soil profiles, caused 17.2 and 33 % reduction of temperature compared to nano-clay and witness treatments. The results also showed that, there were significant differences between treatments in mean weight diameter (MWD) and geometric mean diameter (GMD) and the highest amounts of this index related to nano-clay treatment (p<0.05). Based on the results of this study, the use of sand mulch and nano-clay by reduces the temperature and improving the stability of aggregates, increases the volume of soil moisture in the subsurface layers by 30 to 45% and also increases the retention time in soil moisture and reduces irrigation frequency compared to the state without protective action in the soil. Therefore, the application of the methods used in this study, provides the required moisture to the plants to establish vegetation in the wind erosion centers of the study area.

Soil as a bed of life plays an important role in meeting the nutritional needs of human societies. But due to unscientific poisoning, it is eroding and causing problems for humans, especially in arid areas. Today, a significant part of the soil of these areas is out of use and is practically not suitable for agriculture and exploitation. In addition, by destroying the soil structure, conditions are provided for the movement of soil particles under the influence of wind and water, one of the destructive effects of which is the destruction of the environment. Therefore, since soil is the only source of nutrients, its protection not only reduces evaporation, but also prevents salinization of the soil and also improves plant yield and growth. Therefore, improving the physical and chemical properties of soil and increasing its resistance to corrosive agents (water and wind) is essential. One of the important and efficient methods to improve the physical and chemical properties of soil is the use of mulch, which controls the physic-chemical and biological degradation of soil. Numerous studies have been conducted to investigate the effect of mulch on the physical and chemical properties of soil in and outside the country. One of the arid and desert areas of the country where the decline of natural areas today has caused environmental degradation and also the expansion of erosion centers is Sistan region which has been exposed to soil degradation due to wind erosion and poor vegetation due to lack of water and soil moisture, which in turn has expanded desert areas. This phenomenon has intensified and spread sandstorms and dust. Therefore, due to the importance of studying soil conservation methods and also the urgent need to provide a suitable model compatible with climatic conditions in Sistan region and achieve a principled and efficient management for sustainable use of soil resources in this region, some research studies are needed. Accordingly, the aim of this study was to investigate the long-term effects of using sandy loam and clay nanoparticles on some physical and chemical properties and soil erodibility indices in one of the erosion centers of Nimroz city in Sistan region.

The experiment had been conducted in a randomized complete block design with 3 treatments in 4 replications. The treatments included: nano-clay, sand mulch and witness. In this study, the sand mulch was prepared from windy sediments deposits of the Sistan plain. Also, to prepare nano-clay, sediments from floods that entered Sistan River were used (to pulverize the flood sediments, ball mill were used and to determine the particle size and main elements, DLS and xrf methods were used, respectively). By sampling from each treatment, the physical chemistry characteristics were measured. To study the physical properties of soil, hydrometer method was used and the soil texture was determined. To investigate the chemical characteristics, the soil properties such as organic carbon, acidity (PH), electrical conductivity (EC), sodium absorption ratio (SAR), Na and available P were measured in laboratory. Irrigation of the studied treatments was done by clay method. The pottery used in this research is about 40 cm high and 5 cm in diameter. Sour tea was the plant cultivated in this study. Experimental treatments in this study included: Control treatment, with aerated sand and clay nanoparticles, was coducted in a randomized complete block design with four replications. Statistical analysis of data was performed using SPSS 23 software. The means of the studied parameters were compared using Duncan's multiple range test at the level of 5%.

Based on the results obtained from the particle size distribution, the findings indicated that the percentage of clay, silt and sand at a depth of 0 to 10 cm in the soil of nano-clay treatments and wind sand cover at 5% level significantly differed with the control soil. The highest percentage of sand was in the sandy and nano-clay soil cover treatments, respectively, and the highest percentage of silt was related to the control treatment. Also, the highest values ​​of clay percentage were measured in the nano-clay treatment and the lowest in the wind-blown sandy soil treatment (p>0.05). Particle size in the surface layer of the findings indicated significant changes in the percentage of silt and clay in the treatment of aeolian sand cover. In the same vein, with the preparation of sandy loam soil, the particle size was mainly in the average sand size (0.3 mm), which during the study period was 12.1 and 7.9% of the particles in the average silt (0.031 mm) and clay with > 0.0039 mm, respectively. In analyzing the amount of the above-mentioned parameters in the depths of 10-30 and 30-30 cm of the soil, the findings showed no significant differences between these variables in the treatments of wind-blown sand and control condition. However, the values ​​of these parameters in the nano-clay treatment showed a significant difference compared to other treatments. In control treatments, the percentage of sand, silt and clay decreased by increasing depth of the trend. However, in the treatment of aeolian sand cover, except for the percentage of sand, the trend of changes in the percentage of silt and clay increased. Moreover, in the nano-clay treatment, the studied parameters remained unchanged and, in general, the particle size distribution had the same structure in the studied layers. In the study of the percentage of soil saturation moisture in the treatments, the findings indicated that the rate of this parameter is higher in the nano-clay treatment compared to the two treatments and aerated sand cover. The mean values ​​of this parameter in the mentioned treatments were 33.9, 18.9 and 8.6%, respectively, which are significant at the 95% probability level. The trend of changes in this parameter in other sampling depths compared to the control treatment showed a significant difference. In general, its values ​​in nano-clay and sandy loam treatments are higher than the control treatment. In examining the texture distribution of the collected samples, the findings indicated that in the surface layer (0 to 10 cm) the soil texture was in sandy loam sandy loam treatment.

In this research, which was conducted for the first time in Nimroz city in the north of Sistan region, the long-term effects of nano-clay and aeolian sand cover on physicochemical properties and some soil erodibility indices were investigated. In examining soil physical properties, the results showed that the percentage of clay, silt and sand under the protective effect of soil in the studied treatments are different. In the surface layer, the values ​​of the studied variables in control, nano-clay and aeolian sand cover treatments were significantly different (P <0.05). In fact, with the use of aeolian sand cover on the soil surface with a particle size of 0.316 mm, the soil texture was changed from loamy to sandy loam class and in other sampling depths that did not use sandy loam underwent no significant difference compared to the control treatment. In nano-clay treatment, although changes in the values ​​of the above variables had no effect on soil texture, there was a significant difference in particle size distribution compared to control and aeolian sand cover at all sampling depths. In addition, the presence of nanoparticles among soil particles for increasing the specific surface area had a significant effect on water absorption and thus increased soil moisture. The increase of 1.2 and 1.6 times soil moisture in nano-clay treatment compared to wind-blown sandy soil and control treatments showed a significant difference in the 95% probability level. It has already been found that increasing soil moisture due to the presence of clay nanoparticles in the soil increases the total specific surface area and this in turn increases moisture absorption due to hydrophobicity and high moisture absorption of clay in the soil, which is consistent with the results of this study.

The aim of this research was Study on soil chemical and physical properties at various ‎depths of Hamoun wetland soil ecosystem causes in recent decade floods. In this research soil ‎samples were taken from the 0-5, 5-50, 50-75 and 75-100 cm depth at each location, and analyzed ‎for pH, EC, ESP, CaCO3, organic mater, organic carbon, potassium, nitrogen, phosphorus, SAR, ‎SP, calcium and texture. The data was organized and entered into Statistical Package for Social ‎Sciences (SPSS) software version 20.0 for windows. The data shows that pH, EC, ESP, CaCO3, ‎organic mater, organic carbon, potassium, nitrogen, phosphorus, SAR, SP, calcium and clay has ‎been indirectly relationship with depth. The relationships between this parameters and soil depth ‎has significantly in 1% level (P

Water scarcity is currently one of the worldchr('39')s challenges, especially in arid and semi-arid regions; This is because population growth and rising living standards require more food and water. Therefore, excessive use of natural resources has led to the destruction of potential agricultural lands and natural resources. The final process is floods, dust, and desertification, as a large part of the fertile agricultural lands have been affected by erosion and have been removed from agricultural use and farmer has migrated to other places. As a result, rural farmers have migrated to other areas due to a lack of income. According to the reports, by climate and land use change, desertification affected 6% of the worldchr('39')s arid regions from 1982 to 2015. Such a process in arid ecosystems has led to the development of soil erosion hotspots. Numerous studies have been conducted by national and international researchers on drought and its impact on water resources. Therefore, changes in the hydrological cycle and the impact on water resources have a significant role in land use and natural ecosystemschr('39') sustainability. Hence to the importance of studying land use changes and determining erosion areas that provides a good basis for control and stabilization of erosion centers in these areas. This study aimed to investigate landuse changes and erosion areas by simulating time series images with a high spatial and temporal resolution during periods of water scarcity, normal and wet in the Nimroz region of Sistan.

The study area is located in the north of Sistan and Baluchestan province and part of Nimroz city and the southern part of Hamoon Lake and borders with Afghanistan and at about 480 meters above sea level. This area is mostly flat and lacks topography and natural features. The average rainfall in this area is 50 mm, that most of which falls in winter. One of the Sistan regionchr('39')s characteristics is 120-day winds, which sometimes reach speeds of more than 120 kilometers per hour, accompanied by much dust. The development of the Sistan region depends on the water inflow from the Helmand River for 1,200 km, which originates from the mountains of northern Afghanistan. For this purpose, at first, using micro-scale exponential methods, time series of satellite images with high spatial and temporal resolution were prepared using Landsat and Modis satellite images. To monitor the changes in erosion region, land use maps related to the years of water scarcity (2002), normal (2009), and floods (2019) were extracted, and by evaluating the classification accuracy of the maps, change detection operations were performed using the post-classification comparison method for these maps.

The results shows that the during the period of water shortage to normal, the highest percentage of changes (35.84%) related to the conversion of barren lands to erosion areas with an area of ​​about 32708.68 hectares. The next rank related to conversion of erosion areas to lands Rangeland with vegetation is less than 10% (25.24%).The results also show that during the water shortage to wet, the highest percentage of changes is equal to 25.38 and 25.98%, respectively, and are related to the conversion of erosion area to water and rangeland area. The results also show that during the flood period, with the increase of floodplain areas in the study area, the area of ​​erosion region has decreased by 60% compared to the water shortage period (equivalent to 8059.36 hectares).

Due to the dry climate and low rainfall in Sistan, floods from Afghanistan only meet the water needs of the regionchr('39')s ecosystems. By studying the volume of incoming floods during periods of water shortage, normal and high water, the results showed significant fluctuations in the volume of incoming floods to the Sistan region during the studied periods. Since land use is more affected by climatic and hydrological factors, they play a significant role in land use changes. The results shows that the during the period of water shortage, more than 46% of the study area is eroded region, which has been mainly related to the conversion of barren landscapes, dried bed of Hamoon wetland, and flood agricultural lands to these areas.Therefore, it can be concluded that the changes in the hydrological conditions of inflows to the Sistan region play an important role in the extent of erosion areas with respect to the water needs of water-dependent ecosystems. Despite the environmental crises in Sistan region and its regression, the improvement of environmental conditions in Sistan region requires the demand of water rights in Sistan region from Afghanistan.

Mulberry is one of the plants that are compatible with dry areas. A little research has been done on the irrigation of mulberry seedlings using different methods in arid and special areas of Sistan. In the past, there were suitable climatic conditions for the establishment of mulberry trees in Sistan. If mulberry orchards are revived in the area, in addition to fruit production and the prosperity of the breeding industry, it will also play an effective role in controlling erosion and improving the environment. Due to the harmful effects of water shortage and lack of proper efficient methods used in the agricultural sector of the country, it is necessary to study and use new methods. This research examines the establishment of fruitful mulberry seedlings with three methods of subsurface irrigation, pottery, and drip irrigation in the Helmand watershed. By establishing vegetation while saving limited water consumption in the region, along with its economic aspects for the stakeholders, should also be effective as windbreaks and improvement of the environment for the development of the region.

This research was carried out to evaluate the Mulberry growth using three methods including subsurface irrigation, clay pot, and drop irrigation in dryland regions. Therefore, after preparing hold digs, three soil samples has collected from depth 50 cm of each treatment, and soil characteristics were analyzed. Six-month-old mulberry seedlings were planted in the pits. This research was randomly tested the clay pot irrigation, drop and surface irrigation on mulberry with three treatments and four iterations. Tree high, branch number, diameter, and canopy have been measured. Also, soil moisture was measured at a depth of 60 cm before irrigation. The data were analyzed using SPSS software.

According to the climatic conditions of the region, a total of 700 L of water was given to each seedling. The average moisture content of subsurface irrigation treatment was higher than other treatments. Moisture content in subsurface irrigation, pottery, and surface drops were 18, 14.25, and 13.4%, respectively. The moisture content of subsurface irrigation treatment was 20.8% and 25.5% higher than the moisture content of clay irrigation treatment and drip type, respectively. The mean values have been compared based on the Duncan test and showed the amount of moisture in subsurface irrigation classified in one group and in clay type and surface drops in another group. Statistical analysis showed that there was a significant difference between the moisture content of the three treatments (α< 0.01). Also, significant differences were observed between the mean of plants height of the subsurface (78.5 cm), clay pot (45.5 cm), and drop (59.7 cm) irrigation methods. But, there was no significant difference between canopy, diameter, and branch number. The plant water needs are better provided in the surface irrigation method, and more water is available compared with clay pot and drop irrigation.

The results of this experiment showed that the subsurface irrigation treatment had a better condition in all characteristics than the pottery and drip irrigation methods. Because it provides more moisture to the plant. This situation is due to the lack of high evaporation in subsurface irrigation, water enters the root zone directly through gravity. Therefore, it is concluded that the subsurface irrigation method is more suitable for plant growth than pottery and drip irrigation which reduces the water loss from the soil surface and better moisture distribution.

Excessive use of water and soil resources, especially in arid and semi-arid regions, increases soil erosion, destructive storms, the occurrence of dust, and desertification. Therefore, to prevent environmental problems in these areas, it is necessary to efficiently manage water and soil resources in arid and semi-arid regions. Rainwater catchment systems are one of the management and operational methods, which can be used in arid and semi-arid areas. This study investigates the effect of rainwater catchment systems on vegetation characteristics of the Tasuki region of Sistan. In this research, the ​​rainwater catchment area was selected as the study area, and the adjacent area was selected as the control treatment. Due to the distribution of plant species in the ​​rainwater catchment area, the size of the plots was selected in a way to have more accuracy for plant cover and shrub species evaluation. For this purpose, two linear transects each with a length of 250 meters was placed in each research unit, then every 50 meters, a 3 × 3-meter plot was arranged, and a 1 × 1-meter plot was placed inside them to measure the canopy percentage, forage production amount, litter percentage, number of rootstocks and bare soil surface. Forage was harvested by hand and after drying, was weighed with a digital scale with an accuracy of 0.01 g. The outcomes were analyzed using SPSS statistical software. The results showed that Alhagi camelorum, Aeluropus littoralis, Tamarix stricta, Haloxylon aphylum, Hammada salicornica species have grown in the study area, but only Hammada salicornica distributed in the control area. Statistical analysis showed that all the characteristics of the control treatment and rainwater catchment area were significantly different at the one percent significance level, which indicates the proper performance of this system in improving vegetation cover of the area.

Existing challenges in arid regions have caused climatic and environmental problems such as low rain, winds with high speed and intensity as well as lack of vegetation. These problems happen by destroying and transporting particles leading to the influx of sand flowing into agricultural lands and residential centers. This is one of the most concerns of residents in the arid and desert region of the country. Because, it causes a lot of life and financial losses, the move of sands, and the formation of sand dunes are influenced by interactions between wind flow, the site of deposition, and the morphology of the sedimentation site that gives rise to wind landforms. The vegetation cover plays an important role in determining the morphology and dynamicsby influencing transportation conditions and trapping the sand carried by the winds. This process takes the form of creating a wind vision during a natural reaction, with the creation of the Nebaka phenomenon. The phenomenon appears in desert areas to neutralize wind erosion stress. Accordingly, the presence of vegetation is a prerequisite for Nebakas and controlling the flow of sand flows in arid and desert areas due to the specific climatic conditions in these areas. Numerous studies have been conducted to investigate the effect of vegetation factors on Nebaka formation. The volume of Nebakas is influenced by the vegetative form. The volume of its constituents is different from each other. Vegetation factors have played an important role in the development of Nebakas. Studies have shown that the vegetation cover has the main role in the formation and development of Nebakas so that vegetation reduces sediment replacement and limits its source. Among the critical areas that are referred to as the main focus of wind erosion, the Sistan region has always been affected by wind erosion. The present study was conducted with the aim of investigating the effect of vegetation restoration on morphometric components of Nebaka and its effect on sand dunes stabilization in the Nimroz area of Sistan province.

To achieve the purpose of the present study, after floodwater spreading and forestry operations in the Nimroz area of Sistan during 2003, parameters of Nebaka including Nebaka high, Nebaka base diameter, Nebaka volume, vegetation cover, plant height, wind direction, and back to the wind in 45 Nebakas to the Tamarix species were measured at different time intervals in a 16-year period by restoration vegetation and installing 5 linear transects with a length of 50 m randomly in the area. Then, by measuring the morphometric properties of Nebakas, the correlation of morphometric components was investigated using correlation analysis and multivariate regression analysis.

In the correlation analysis regarding the morphometric characteristics of Nebaka, the findings showed that a significant correlation (at the level of 0.99) of the plant characteristics such as vegetation cover and high plant parameters such as Nebaka high, Nebaka base diameter, Nebaka volume, wind direction, and back to the wind. The multiple regression analysis approved 92.9 percentage of the volume changes of the Nebaka with the vegetation cover. Investigating the amount of sediment stabilized in the Nebaka also showed that increasing vegetation wills increased the volume of Nebaka in such a way that with increasing vegetation, the volume of Nebakas on average increased from .0.53m3 in 2008 to 15.69m3 in 2018 with the amount of stabilized sediments increased from 184.97 ton to 879.79 ton. The statistical comparison of the measured data showed that there is a significant difference (at the level of 0.01) between the mean stabilized sediments in Nebakas during the research process. According to the results of the study, the restoration of vegetation in the study area shows a good background for the formation of Nebakas. As a result, a considerable amount of sands has stabilized in these Nebakas.

In this study, the role of wind activity in the formation and development of Nebaka areas where wind power was low was confirmed. Based on the result of this research, a significant amount of wind sediments has been stabilized in Nebakas. As a result, the Sistan area is always affected by wind erosion and the problem of sand dunes. The method of restoring vegetation by doing flood and forestry plans in susceptible areas is effective to stabilize the sand with the creation of the Nebaka phenomenon in the study area. Re-vegetation in the study area has provided a good basis for the creation of Nebakas in the region.

Aim of this research was Studying and Recognition of lithology and Erosion Rivers in Sistan region. To done this research distinct situation of rivers according of basin and collected inform about basin of Sistan and review different parts of them such as type of erosion in river banks by using available reports and filed works. We have used available scale of 1:50,000, 1:250,000, Geologic maps, field observation and global positioning system (GPS). We found erodible area of river banks according to scale of 1:250,000 erodible Geologic maps. The data show that’s the main factor of cause to erosion is effect geologic conditions. The main parts of the basin covered with sediment of quaternary which is very sensitive to water erosion. The sistan rivers classification shows that stone, alluvium and other are 20.7, 38.1 and 41.2 percentage of rivers length, respectively. 7.2 percentages of area rivers occur erosion that bed and banks erosion are 85.1 and 14.9%, respectively.

The ecosystem of arid and desert areas has difficult conditions for plant growth and development, due to lack of moisture, high temperature, strong winds, soil erosion and land degradation caused by human activity, as a limited number of plant species are able to survive. Wind erosion is one of the problems in these areas due to lack of vegetation. There is a need to increase vegetation to prevent this erosion. In such areas, native plants with the ability to adapt to hard environmental conditions are valuable species that are important to be identified. To conduct this research, two random transects with a length of 250 m were first placed to measure the vegetation status and at a distance of 50 meters from each other, plots were thrown 3×3  meters according to the condition of the cover.Also, 1×1m plots were used to measure the percentage of canopy, bare soil, rocks, density and litter. Three soil samples were taken and some of its characteristics were measured. To estimate the amount of eroded soil, the remnants of erosion-resistant areas as well as the depth of degraded soil around the stems and roots of shrub and shrub species were measured at 10 points. The protective performance of plant species against wind erosion was estimated using the difference in the height of the stabilized soil under each canopy relative to the surrounding soil.The results showed that the species of Tamarix sp, Alhagi camelorum, Aeluropus littoralis, Suaeda fruticosa have good adaptation to areas subject to wind erosion in the study area. The predominant species in the region is the Tamarix shrub. Each turmeric shrub has an average canopy cover of 2 square meters in this area, which stabilizes an average of 3.3 square meters of soil. On average, during the droughts of the last 10 years, about 102 tons of soil per hectare of the area has been eroded annually. Therefore, it is suggested that in order to improve the environment of the region, a suitable conditions should be provided for the establishment of species compatible with the region.

Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased moisture in the plant root zone. For this pupose, three soil samples were collected from 0-50 cm depth and their pH, EC, C, Ca, Mg, K, Na, ESP, available phosphor, cations and texture were tested. This research had eight treatments including plant, soil and irrigation which have been done in split split-plot in four  replication durig tow years. After plating a 20 cm layer of sand was applied on the soil surface in each pit. In this experiment, soil moisture was measured monthly and plant growth was measured in growing season. Statistical analysis of the data was performed using MSTAT software. Result showed that the amount of moisture was 28% higher in sand compared to other treatments at the level of 99%. According to the findings of statistical analysis on the impotance of methods used for soil moisture, the sand along with subsurface irrigation of toot had better groth at the level of 99% and were in class A and the other treatments were in class B. The conclusion was that sand causes decreasing in capillary, reducing soil evaporation, increasing moisture around root zone of the plants and water and soil conservation.

Water is crucial for survival and development. Long-term access to water resources provides the ground for scientific and technological developments. Geographically, Iran is located in an arid part of the world. Water scarcity and mismanagement could create a water crisis in the world, and that droughts may exacerbate different environmental and socio-economic aspects of life. As revealed in a report issued by the United Nations’ Environment Programme, 80 percent of the world’s population currently live in places with no water security, and that 1.5 billion people throughout the world are facing anhydrous risk. As Iran has, in recent years, been affected by drought, access to water for agricultural, industrial, and drinking purposes is now of great concern for inhabitants of the country’s drylands. According to the reports issued by the World Bank, mismanagement and inefficiency of irrigation systems are the main reasons for water insecurity in the world. In recent years, mismanagement of available water resources in the arid region has followed by the destruction of natural ecosystems that are dependent on water resources. As a result, changes in land use over a long period and the expansion of desert areas have led to environmental degradation. Sistan is located in an arid region in Iran where difficulty to access surface water resources due to drought in recent years has brought about environmental degradation in the region. Low precipitation (50mm), high temperature (48o), high transpiration (5000mm), and 120-day winds are among the specific climatic conditions that characterize the region. Sistan is also hit by floods for a limited period when the Hirmand river flows as a result of torrential rainfall in Afghanistan, providing the required water for its 120,000 ha agricultural land.

This study sought to investigate the environmental impacts of hydrological drought and traditional utilization of floods streams on Land Degradation and Desertification in Sistan. Located at the southeastern border of Iran and Afghanistan, Sistan forms part of the Dasht-e-Lut desert land, possessing an extreme arid climatic regime. The region is a roughly flat and featureless arid plain with an average height of 475–500m ASL in its eastern parts. To realize the purpose of the research, the hydrological drought status of the Hirmand river was investigated. Using the Streamflow Drought Index (SDI), the hydrological drought was then calculated for 22 years. The distribution and utilization of flood streams in the Sistan area were examined via Infield operation. On the other hand, the Irrigation system of the area was examined through library studies and the factors affecting the circulation of surface water resources were identified. Weighting these variables via Analytic Hierarchy Process (AHP) and integration of data layers, access priority map of sectors to the water resource was estimated. The land-use map of the years when the hydrological drought occurred and didn’t occur were extracted through the Landsat satellite images of the years 2002 and 2018. The identification of changes in the region was then carried out by assessing the accuracy of the images and their classification, using the comparison approach. Moreover, the land-use change maps were overlapped whit the access priority map of sectors to the water resource to investigate the effect of the utilization method on desertification and land degradation.

The findings of this study showed that the severity of drought in Sistan has increased over the past 18 years. On the other hand, the findings for the areas with years of hydrological drought indicated that barren land had increased by 41 percent, and that agricultural, residential, and water zone areas had decreased by 61, 31, and 84 percent respectively. It was also found that the distribution and transmission of incoming floods to the Sistan area lead to limited access to these surface waters in areas such as Hirmand (Gregory sector), Nimroz (post ab sector), and Zabul (Central sector) because of their seasonality and uncertain continuity. The most land-use changes were found to be the conversion of water zone, (equivalent to 12581 hectares) agricultural lands (equivalent to 3073/22 ha), and poor rangelands (equivalent to 4495/8 hectares) into barren lands where access to floodwaters is limited.

This study proved the clear environmental effects of hydrological drought and traditional utilization of water resources on the Sistan region. Reduction of streamflow in the Hirmand river due to the recent occurrence of hydrological droughts and limited access to water resources because of the irrigation system and the traditional methods of utilizing water resources led to the land-use change as a result of the destruction of water-dependent ecosystems, increasing the desert areas and critical points in the Sistan area accordingly. Having said that, breaking the drought, improving environmental conditions, and using efficient production methods require new approaches for proper utilization and management of water resources in the Sistan area.

Aim of this research was study effect of flood on soil carbon and nitrogen sequestration the soil of the habitat of three plant species Tamarix sp., Halostachys belangeriana and Suaeda  fruticosa Sistan region. To do this research first by survey satellite images, the areas were found that watering and no watering (control treatments) from Afghanistan floods. Then select the introductory treatments, 48 soil samples with five repetitions were collected randomly at 0-30 centimeter soil depth and analyzed Organic carbon, nitrogen, sequestered soil carbon and sequestered soil nitrogen from the three flood and control sites. In order to the compare carbon sequestration and nitrogen between treatments and control treatment using the one-way analysis of variance. Data shows that there were significant difference between soil organic carbon percentage and nitrogen in 0.05 levels. The Pearson correlation coefficient between data shows that the maximum amount of correlation of organic carbon and nitrogen was with organic matter (96%) which was significant at the 99% probability level. The result also shows that the above parameter has 99% negative correlation with soil apparent specific weight. Average comparison mean of carbon sequestration and nitrogen of soil shows that the maximum carbon sequestration and nitrogen were in Tamarix forest with 21.89 and 2.43 ton/ha, respectively. This is equivalent to 80.33 and 8.01 ton of carbon dioxide and air nitrogen dioxide in soil which 2.2 and 2.5 times of carbon sequestration and nitrogen of control treatment (9.76 and 0.97 ton/ha). Environmental economic value of carbon sequestration and nitrogen in floodplain is equivalent $ 300 and 85 billion per hectare, respectively. It is recommended to prevent further effects of climate change on the dry and sensitive ecosystem of Sistan region, increase vegetation through the flow of incoming floods from Afghanistan to eroded areas and seedlings should also be planted in these areas.

The aim of this study was investigating the effects of incoming floods from Afghanistan on the quantitative and qualitative changes of groundwater resources in Sistan plain. For this purpose, first by determining the direction of flood flow in Sistan plain, 16 wells drilled near the flood flow were selected. Estimates of reservoir volume changes as well as comparison of rainfall in the region in the same period. In the following, Using groundwater balance equations and single hydrograph equations before and after flood entry, quantitative changes in groundwater resources in Sistan region over a period of 4 years (1394-1398) were investigated. The qualitative changes in aquifer with sampling of observation wells during the balance and investigation of time changes in water quality parameters such as electrical conductivity (EC) and acidity (pH) was analyzed. The data shows that the floods increased the water level in the wells by an average of 0.39 meters the process of change has a high correlation (R² = 0.85) with the volume of floods in the region. Also, the hydrographic survey of the plain unit indicates significant changes in groundwater level before and after the flood in the area. As, during the 4-year period, the average water level is 2.16 meters higher than before Floods have increased. With the flooding amount of 20.66202 million cubic meters during the balance period, the reservoir volume has been naturally increased. Due to the low rainfall in the region, the nutrition of groundwater aquifers is affected by low rainfall.

The aim of this research was to study how water use management can increases vegetation cover inrainwater catchment systems. The study was conducted through comparison of two methods of irrigation, i.e. traditional sub-surface drip irrigation and drip irrigation. Three soil samples were taken and analyzed from three locations in north of Sistan from a depth of 50 cm. A furrow was dug with a base depth of 60 cm, width of 50 cm, and  length of 48 m. 12 holds were dug 4 m long, 70 cm deep and 50 cm in diameter. For subsurface irrigation, a 3-inch pipe with a length of 48 m was placed horizontally in the furrow. At 8-m intervals, 2-mm holes were made in the pipe. In the drip irrigation method, a ½-inch pipe with a length of 48 m was placed on the furrow and drippers were connected every 8 m. In each pit, a mulberry tree was planted. Soil moisture was measured every month and growth was measured each season. Data shows that the amount moisture, increase in plant height, and trunk diameter in subsurface irrigation were 53.1, 91.6, and 52.8 percent more than drip irrigation, respectively. Statistical analyses show that soil moisture, plant height, and trunk diameter were significantly higher in subsurface irrigation (P<0.05). In subsurface irrigation, water directly flows to the root zone. Because in this method transpiration is less than drip method, subsurface irrigation has good potential to establish suitable moisture levels for plant growth.

The land-use change is one of the critical worldwide issues that has caused a problem in natural resource sustainability. The dynamics of land-use and land-cover change (LULC) affected by the anthropogenic activities and climate change in arid areas, were caused environmental degradation of these areas. This process has the negative effects on soil physicochemical properties. Soil degradation is the key component of land degradation that affected by land-use changes. So that it causes organic waste carbon, decreases the soil aggregate stability and structure and, consequently the raises of soil erodibility. So to understand the impacts related to these changes in land-use (LU), assessment of the effects of these changes on soil characteristics is important. Therefore, the current study aim was to investigate the effect of land-use change on physico-chemical characteristics of soil and erosion in Sistan area.

This research has done in Sistan area. This area laid southeastern border Iran and Afghanistan. The Sistan region forms a part of the Dasht-e-Lut and hence an exhibits extreme arid climatic regime. The region is nearly flat and featureless arid plain with an average height of 465–500m ASL in its eastern parts. In this study, at first spatial land-use changes in Sistan area determined. To achieve this purpose, used satellite images. By using the Landsat satellite images related to the years 2001 and 2019, the land use maps prepared, and by comparison approach in Idrisi Selva software, the map of land-use change was extraction. After that, the areas that converted from rangeland to flood-agri and bare land determined and that accuracy were assessed. Infield operation, 60 soil samples were collected from tow depths 0-25 and 25-50 cm in different land-use such as rangeland, flood-agri, and bare land. The Samples were collected in a completely randomized block design. To study the physical properties of soil, by hydrometer method, by the soil texture, and by measuring the mean weight diameter (MWD), the geometric mean diameter (GMD) and dry stable aggregates (DSA), the aggregate stability was determined. Also, the soil moisture and bulk density were measured. To investigate the chemical characteristics, the soil properties such as organic carbon, acidity (PH), electrical conductivity (EC), sodium absorption ratio (SAR), CaCO3, Na, and available K and P measured in the soil laboratory. The soil erodibility index calculated five characteristics, including sand, silt with fine sand, organic matter, soil structure class, and the infiltration rate class of the soil profile. To analysis the mean of parameters among different land uses were used the Duncan test.

The result of the study of physical properties showed that the percentages of sand, silt, and clay particles among the land-use that under study were significantly different. So that by the land-use change from rangeland to flood-agri and bare land, the distribution of soil particle size differently, that consequently the soil texture has changed from loam-silt-clay class in rangeland to lighter class loam-silt and loam-sand in flood-agri and bare land respectively. According to this change, the aggregate stability of soil inland converted from rangeland to flood-agri, and bare land 34 and 45 percent have decreased. Also by land-use change, the soil moisture 18% and 43 % has decreased respectively. The results also showed that the bulk density of soil, acidity, electrical conductivity, Na, CaCO3 and absorption ratio (SAR), increased in converted land-use whereas, the organic carbon and available K soil, have decreased significantly. In addition, after land-use change, the erodibility index has increased significantly (P < 0.05). So that the amount of this index in flood-agri and bare land compared to the rangeland land-use, more than equal 4 and 7 respectively.    

In this study, for the first time, has investigated the physico-chemistry characteristics of soil and erodibility in land converted from rangeland in Sistan area. The results revealed that the conversion of natural rangeland to flood-agri and bare land had negative effects on the measured soil properties. So that the percent of sand has increased, that changed the distribution of soil particle size, and according to that, the soil texture has changed also. This caused the aggregate stability soil to reduce. In addition, by decreasing the soil moisture, the plant growth has limited in this lands and given the high evaporation potential in Sistan area, the evaporation from land surface increased and according to that the electrical conductivity, acidity, Na and absorption ratio (SAR) in converted lands have increased, whereas, the organic carbon and available K soil, have decreased. This process has caused the Soil degradation, that affected by land-use changing. Therefore, the land-use change by destroying the soil structure and land-cover in converted lands, cause increases the potential of erodibility, that given exist environmental crises in Sistan area, has required the suitable planning to principle productivity of lands in Sistan area.

The object of this research is evaluated of flood productivity on vegetation cover changes. For this purpose, 5 linear transects with a length of 50 m were installed before flooding in the year 2006. In each of these transects, two plots 3×3 were identified at a height of 50 m at the beginning and 1% in length, and within each of them a plot of 1×1 was laid out for uniform harvesting at equal distances, their coordinates using specific GPS and feature the percentages of canopy cover, forage production, bare soil percentage, density and litter before starting flood spreading in 2003 were estimated. In addition, the vegetation characteristic changes were measured in the same place after the flood propagation in the year 2019. Landsat satellite images for a period of 16 years (2003-2019) was also used to study vegetation changes before and after flood propagation. For this purpose, after applying pre-processing on the images, the vegetation index was adjusted according to the soil adjusted vegetation index (SAVI) and soil water index (SWI) over five different time periods. Field results showed that with the application of flood propagation application, the amount of forage production increased from 68 to kg/ha, the percentage of canopy cover increased from 5.9 to 31.4%, as well as the amount of litter from 2 to 16.8% and bare soil decreased from 92.1 to 51.8%. Statistical analysis of vegetation characteristics before and after flood propagation revealed a significant difference between these parameters (p<0.01). In addition, the results showed significant changes in the SAVI and SWI indices over the period. The SAVI and SWI indices increased from 0.027 and 0.5 in the year 2003 to 0.49 and 1 in the year 2019, respectively, and the trend of changes in these indices showed high correlation (R² = 0.65) in flood propagation area. The results of this study showed that flooding productivity by providing soil moisture in the study area improved germination and plant growth conditions, which resulted in the establishment and improvement of vegetation cover in the floodplain.