فهرست مطالب نورالله نیک پور

Many factors are involved in agricultural development such as climatic conditions, soil moisture, evapotranspiration and etc. For their effectiveness, it is necessary to examine the key parameters. Timely and accurate monitoring of these committees with the help of satellite imagery is a necessity in this regard. Herat plain is one of the plains where soil salinity and lack of moisture has led to a critical situation of gardens and agricultural lands.

In this research, we have tried to study soil salinity, soil moisture and actual evapotranspiration using the MODIS sensor data for the four months of February, May, August and November 2017.

The first stage of vegetation survey shows 0.4 in May (growing season). While the maximum land surface temperature was recorded in August (54 ° C) and May (45.15 ° C). Then, in the next step, using the results of two indicators of vegetation and land surface temperature, the humidity of the area is investigated by TVDI. The humidity of the region was divided into five classes from zero to 0.5, which indicates the low soil moisture and dryness in the Herat plain. Finally, due to the dryness of the area and to verify the TVDI method, field soil samples were taken from different parts of Herat and especially its agricultural lands to estimate the soil salinity (EC, PH and soil moisture). The results showed that the soil moisture content of the samples at a depth of 5 cm above the ground varies between 0 and 0.3. Also, out of 12 soil samples, 6 samples have saline soils and one sample has saline-acid soils. Of course, it is also important to note that some of the agricultural lands whose soils are in the saline group are dry and left to their own devices.
Finally, the study of actual evapotranspiration with the SEBAL algorithm showed that in this region, despite the lack of moisture, actual evapotranspiration is very high, especially in the hot month of August.

Soil salinization is one of the dominant processes of land degradation in arid and semi-arid regions.  Soil salinity is one of the most important problems affecting many parts of the world. Salty soils in agricultural areas reduce the annual crop yield of most crops. As a first step, soil sampling and Landsat images are pre-processed. Different salinity indices such as NDSI (normalized salinity index), BI (brightness index) and SI (salinity index) were used to map the salinity of the study area. As well as Laboratory measurements of electrical conductivity (EC) and soil acidity (pH) have also been performed. In this regard, the values of three salinity indices NDSI, BI, SI for 2017, 2015, 2010, 2005, and 2000 were calculated in ENVI and GIS software. Based on the results of satellite imagery analysis, saline soils in the west and southwest of Ilam province (sub-basins of Mehran, Musian-Abdanan, Abbas-west-east and Molab basins) are located. According to field surveys and soil sampling for different areas of Ilam province, it was found that pH values below Mehran basin, south Dehloran and downstream of Simareh Dam are above 8.5 and indicate alkaline and sodium soils. And other examples show unusual, up to slightly salted soil. This means that the results of the remote sensing analyzs partially confirm the data obtained from estimating soil EC and pH values in the study area.

Animated sand dunes are a major threat to wind erosion, causing severe damage to transportation networks, agricultural products, water resources and residential areas ) Ahmadi, 2006). Sand hills are also one of the most important facets of wind erosion. Sometimes the speed and direction of the winds in the area can help a lot to understand the morphometric properties of sand dunes (Pourmand et al., 2015). The use of remote sensing over the past few decades as a tool to study the characteristics of sand dunes and study its changes over time has made it possible to extract former climatic diets and monitor marginal areas that are prone to desertification (Otterman, 1981; Tucker et al., 1994). Image processing is one of the techniques used in data analysis and interpretation of satellite data to study natural hazards such as sand dunes. In general, monitoring the changes and spatial-temporal progress of sand dunes as one of the most important environmental hazards in arid regions of the world is essential. Therefore, Sistan plain in eastern Iran in recent decades due to environmental and human factors, influx The flow of sand and the advance of the sand dunes in it have stopped human activities in most parts of it and have caused irreparable damage. Studying this environmental risk in this area will not be without merit to reduce its destructive effects and sustainable management in the area. This study uses the time series of Landsat satellite data to monitor the trend of changes in the sand dunes of Sistan plain and its effects on people's social life. To do this, Landsat 5 and 7 satellite images (July and August images between 1995 and 2018) were used. After obtaining the required data from USGS site and forming a database, the steps of correction and analysis were applied to them with the help of GIS and ENVI software, and then four Landsat image tiles were mosaiced together to completely cover the study area. . In this study, a field visit was made to identify the location of hills and other sand forms and during the maximum likelihood classification in Envi.5.3 software environment, the affected areas of hills and other sand forms were identified and The changes in this phenomenon were compared between 1995 and 2018. Several factors affect the movement of quicksand in the Sistan plain. One of the most important is the 120-day winds in the dry seasons, which burn at 110 to 170 kilometers per hour. The results of the Golbad drawing for July are shown in Figure 3. July, like June, which is affected by the 120-day winds of Sistan, offers a similar pattern both in terms of direction and speed of wind. This month's wind direction is northwest to southeast. Satellite images were taken over six periods to study how sand dunes developed and spread in the region in July and August. Between 1995 and 2000, with the drying up of Hamoon Wetland, the spread of sand dunes on the shores of the lake is clearly visible. Although Lake Hamoon has been flooded in 2015, the spread of sand dunes affected by the lake's dryness in the past is still visible, due to strong winds and the loss of vegetation during the pre-basin period. It's time. In 2010 images, the lake's flooding during this period had a positive effect on stabilizing and reducing the surface of the sand dunes. However, in the following years, with the decrease of the lake's water level, the amount of sand dunes in Sistan plain has increased again, which can be clearly traced from the prepared images. Analysis of meteorological data on wind direction and speed in this area showed that the prevailing winds determine the movement of sand dunes, 120-day winds, and there is a direct relationship between wind speed and the rate of movement and progress of sand dunes. Landscape sandstone expansion plans from the Landsat Measures Processing for July and August, the most turbulent months in terms of winds, were developed in 1995 and 2018 to monitor changes in the region's sand dunes. Which clearly depicts the dynamics of sand dunes in different years. According to the results of a study of Landsat satellite remote sensing data, the area of sand dunes in August increased from 8.23 percent in 1995 to 11 percent, and in July 2018 from 7.55 percent to 10 percent of the range Cover the study. Which indicates an almost dramatic increase in sand dunes. Also, the drastic changes in the area of Lake Hamoon from 1995 to 2018 can be clearly seen in the prepared maps, and it is said that the expansion of sand dunes in different years is directly related to changes in lake level at different times. Field studies show that during the frequent droughts in the Sistan region, the movement of sand dunes has been so high that it has buried a large number of rural houses and destroyed agricultural lands. This has led to the unemployment of a large number of farmers in the region and has caused severe damage to water supply facilities and canals, so that its compensation requires a lot of time and money. Many people in the area have migrated to escape the situation, and many have resorted to false jobs to earn a living, including fuel smuggling, smuggling and tourism. Comparing the results of this study with the study of writing (2007) that examined the damages caused by the relocation of sand dunes in eastern Zabul, shows almost the same results, with the difference that this study generally considers the Sistan plain. Data and a complete study of the trend of changes in sand dunes in Sistan plain show, but the study study in 2007 was only focused on sand dunes in the east of Zabol.

Coasts are among the most important and strategic places with special importance for countries. Having 673 km of water border in the north and 2098 km in south, Iran has a great potential for commercial, touristic, and military purposes. The beaches, as one of the most endangered places under the influence of sea waves, are constantly undergoing geomorphological changes. Tombolo is one of the effects of coastal sand compression that is affected by waves and the resulting hazards always threaten the inhabitants of the area, so it is necessary to study this effect. The purpose of this study was to monitor the time series of geomorphological changes in Tombolo of Bandar Tang on the coasts of Sistan and Baluchestan province using remote sensing and field surveys. The Tang Seaport tombolo is located on the southeastern coasts of Iran between longitude of °59 ′53 ″10 to °59 ′54 ″10 E and latitude of °25 ′20 ″29 to °25 ′21 ″01 N. This geomorphological feature with the area of 0.3 km2 is located at the south of Sistan and Baluchistan Province, Konarak County, 97 km distance from the west of Konarak at the south of Tang Seaport. therefore, it is essential to study the geomorphological shape of coasts in order to manage the reduction of such hazards.

The present study was conducted using statistical analysis, field survey, and remote sensing. In order to investigate the geomorphological changes in the tombolo of Tang Seaport, different information was used. In this regard, the Landsat satellite imagery from 1972 to 2016 was used. To analyze the regime of the atmospheric and sea currents in this region, the statistics of the stations close to the region was used, which included the daily statistics of Chabahar and Jask synoptic stations, and statistics of the PMO buoy station as well as marine buoy station at city of Chabahar. In order to analyze the geomorphological features of the tombolo in Tang Seaport, Gis & Rs was used. Satellite imagery was provided during the statistical period and underwent band composition using ENVI software. Then, it was digitized in GIS software and the morphometric changes of the tombolo and sandspit were calculated. Afterwards, using WRPlot software, the wind rose and wave rose of the region were depicted and their association with geomorphological changes was investigated.

The obtained results showed that during the studied statistical period, the tombolo’s connection to the mainland was interrupted in four cases in 1972, 1989, 2000, and 2016, the main reason of which was the surges along the wind direction that have eroded and destroyed the tombolo sand spit. The main cause of these currents was the summer monsoons of the southeastern Asia, which cause the anomalies in the Sea of Oman currents every year. Since the tombolo sand spit is located at the north of island, the changes and power of the waves in the Sea of Oman from west and east have eroded and removed the sand spit so that the western direction of the waves in 1988 and 2015 and their eastern direction in 1999 have resulted in the disconnection of this geomorphological feature. The existing evidence showed that the eastern currents in the Sea of Oman were the cause of the disconnection of the tombolo sand spit in 1972, which had acceptable correlation with the sand spit separation in 1999. According to the results of the above table, physiography of the tombolo and its sand spit as well as position of Tang Seaport and its sand spit had a close relationship with the relatively calm years in the Sea of Oman, and whenever the seasonal currents of Southeastern Asia had less energy, the erosion processes were weaker and sedimentation was increased, so that the specific geomorphological changes occurred proportionate to the direction of the waves in that year.

Studies have shown significant geomorphological changes in this phenomenon. The results of field visits, time-series analyzes (45 years) of Landsat satellite data and statistics of synoptic and buoy stations showed that in some years severe sea currents and waves caused extensive geomorphological changes, such as discontinuation of sandbags and elimination of tombolo. The harbor has been narrowed, so that during the statistical period, waves in 1972, 1989, 2000, and 2016 interrupted the island's connection with the land through sandy tongue erosion. Marked with time intervals of 17, 11 and 16 years, respectively. Therefore, the active dynamics of the waves in Tombolo, the port of Tang, have prevented the hazards of the waves from creating human settlements in the area. Due to the existing conditions and for the coastal management of Tombolo Port Tang and the use of existing potentials, the construction of artificial barriers for sedimentation of coastal sands seems necessary. It should be noted that this geomorphologic complication has never been eliminated during the period under study and has only undergone changes that have.

Land degradation is a global challenge that results in reduced soil fertility and eventually becomes one of the major environmental issues worldwide. The issue of land use and land cover changes by mankind is one of the most important factors of environmental change at the local and global scale which has significant implications for ecosystem health, water quality and sustainable land management (Foley et al., 2005; Lubchenco, 1998). The problem of land degradation in the Ilam province is affected by a combination of natural and anthropogenic factors, including deforestation, drought, overgrazing, intensive agriculture, increased sediment performance due to soil erosion, evaporation, dam construction and drought. These environmental problems are ultimately linked to changes in land cover and land use. Therefore, it is important to consider land cover and land-use changes to monitor environmental changes and sustainable resource management plans for fragile ecosystems such as Ilam province and provide results to area managers and planners for restoration and prevention.

In this study, we used MODIS Terra Satellite Land Cover Products (MCD12Q1) to study the monitoring of land cover changes in the Ilam province for the period of 2001 to 2013. All data for the study area were mosaicked and sampled with the UTM Global Coordinate System, using the nearest neighbor sampling method. Then they were Geo-referenced and finally, on Gis-Envi software correction operations (geometric, radiometric and atmospheric) were run and then the study area was clipped. The method initially classified the images into 17 classes and then calculated the number of pixels (zeros up to 255) of each class for the duration of 13 years and mapped the trends and percentages of changes occurring to each class.

Shrub forests have begun to grow in size since 2009 and their numbers appear to have increased in the coming years. Conversely, forest-savannahs and savannas in 2001-2007 had a small area (34 pixels in total) of their own, and since 2007 species of this type have become extinct and are not observed at all, in the studied level. The water levels (code zero) in the study area underwent very little change from 2001 to 2013, and only from 2004 to 2008 did the extent of the water levels show greater values than other years. The maximum amount of water in 2005 was 29 pixels (that means, 7250000 m = 500*500*29), which is mostly related to the Karkheh and several pixels of the Simare River in the south and east of the border. But water levels appear to have increased since 2013 due to the construction of several dams in the study area. Also, the levels for urban and residential areas (Code 13) from 2001 to 2013 are consistently 159 pixels per year across the study area, and we don't see any increase or decrease in it. Finally (code 7, 10, 12 and 15), respectively, each are 564.424 and 8.953 and 47.030 and 443.520 pixels for 13 years. That is %99.78 of the area covered. Among these areas, open forest shrubs with 564,424 pixels and no vegetation areas with 443,520 pixels had the highest amount of land cover (%94.5) in the area.

According to the extracted map (Map No. 2) the story lacking vegetation named Code 15 which is marked yellow in the map, is mostly located in the west and southwest of the study area, including the lowland basins, namely Western Abbas plain, Eastern Abbas plain, Chenane, Abadan, Mehran, Dehloran, Salehabad, and Sumar. In some years, due to the increasing trend of land degradation, it is advancing toward the center and east of the region. Overall, the trend of changes in the amount of no vegetation levels over the past 13 years show an increase, and this can be a concerning issue in terms of land degradation. This should be seriously taken into consideration. As the maps show, there is a decreasing inclination in the trend of open shrub forest zones during the study period as well.

Deforestation or vegetation degradation is one of the main drivers of global earth changes, which has significant consequences in terms of ecosystem performance and biodiversity conservation. One of the ways for studying vegetation changes as the most important indicator of land degradation is remote sensing. In this study, in order to monitor the vegetation degradation trend in Ilam Province.After obtaining and preparing the required data (410 downloaded images) in the ArcGIS and Surfer software, the multiplication, mosaic and georeferencing operations are made. Converting format of images into ASCII is the next stage of the study. By converting this format, the total number of 953552 pixels is studied within the range; after removing the lost and negative values, 328042 pixels are analyzed. Besides, using parametric statistical method of the classical linear regression and programming in R software, the trend of slope variations and significance of slope variations of vegetations are obtained for the 17-year period (2000-2016). Results of this study show that the focus of the highest trend of declining slope variations (trend of negative slop variations) is in the NDVI index across the western half of the studied area and the focus of the highest trend of increasing slope variations (trend of positive slop variations) is in the NDVI index in the center and east. Significance of the trend of slope variations also approves this claim. Thus, the focus of the highest trend of slope variations (negative) in the west and southwest of the studied area along with the highest trend of slope variations (positive) in the center and east is significant at the probable level of 0.05

Has been stated in various sources, soil as one of the most important natural resources has a major, role on the lives of humans. Today soil erosion and sediment production, a problem that is increasing day to day process and loss of surface soils and sediment accumulation in dam reservoirs, canals and also sedimentation damage to the country's economy. One of the most important types of water erosion, gully erosion or (Galli formation). This type of erosion and loss of soil due to sediment production and enormous damages to land, roads and infrastructures, is of great importance. Soil erosion is one of the most important factors that threatens large areas of Iran annually and decreases or eliminates the quality of agricultural lands and rangelands. Due to highlands of Iran in comparison with the grounds and surrounding plains (mean elevation of 1250 m), it has been affected by water erosion. So it is very important to study erosion and present management strategies to reduce the impacts of erosion in basins of Iran. This study to Target morphometry gullies and the influencing factors on gully erosion in the South West sub-basin of ILAM (Cham Fusel).
The average height in the area between 50 and 1,200 meters above sea level and has a dry climate with an average annual rainfall of less than 200 mm and the average annual temperature is above 25 degrees C°. In terms of the main geological formation of this area is affected by gully erosion, Aghajari formation (red mudstone, siltstone and sandstone) are related to Miocene period. Basin area of over 150 hectares affected by gully erosion and slope threshold for gully erosion in the area between 8-2 percent.
The research method in this study is field research, library study and morphometric measurements of gully erosion forms. Besides, on the basis of the geological maps of 1/100000 and topographic 1/50000 and DEM 30 meter area, the software of GIS Arc has been used to make the required maps. Furthermore, the GPS device and a camera has been used in the field to harvest. o
The average height in the area between 50 and 1,200 meters above sea level and has a dry climate with an average annual rainfall of less than 200 mm and the average annual temperature is above 25 degrees C°. In terms of the main geological formation of this area is affected by gully erosion, Aghajari formation (red mudstone, siltstone and sandstone) are related to Miocene period. Basin area of over 150 hectares affected by gully erosion and slope threshold for gully erosion in the area between 8-2 percent. The study, which the sub basin in Cham Fusel ILAM province is located in the South West, with the aim of gully morphometric including deep, height, length, height from sea level, and geographical location as well as classification criteria in three sample gully gully of area, In order to identify factors affecting the development of erosion in the basin plain Cham Fusel was evaluated. The results of morphometric and field visits to the region, factors such as climate factors, slope and aspect, geology (Land genus), tectonic activity and faulting, land use, overgrazing of amount plants, including the most important factors recognized were identified in the development of gully. Which layers to extract some of these factors in Arc GIS software designed and based on creation of maps and data to analyze each of these parameters and their impact on Gully Erosion percent has been paid.
According to the morphometric data, it can be concluded that the gullies basin largely toothed and clawed, permanent, of medium to large gullies, which have expanded continuously. Below you can see images of morphometric gullies sample was collected during the field visit of the area. The results show that due to the widespread earthquake in the region in recent years and local faults can be concluded that one of the most important factors in the formation Galli uplift of the Earth. Also overgrazing by cattle ranchers in the area Tuesday Abdanan city, murmury, Dahlgren and ranchers outside the province of Hamedan and Kermanshah provinces such as ranchers who use the area as Qishlaq, Another important factor in the development of gully erosion in the area. Due to the climatic amount of rain, sleet, snow, ice, temperature and wind could be the climate factors in the rise of water erosion. As the geographical location and local climatological data suggests, the study area is influenced by the Mediterranean winter rains. Which are imported to Country from the West in winter and more in the form of showers and hail rainstorm conditions caused severe erosion gully in the area easy. Lack of growth of vegetation and bare Land is another contributing factor is considered in the development of gully erosion in the area. That is because the rainy season in the winter when the soil in the area is almost devoid of vegetation. The lack of vegetation in the region as one of the important factors, has caused soil erosion, its most destructive erosion of the gullies show. Also according to the map slope and aspect of the region was marked within the range of between 2-8 percent and Create Gully and aspect with the West and the South West and North West are more affected by gully erosion. Finally, all factors except factors of land use, all other factors were named among the important factors affecting the development of gully erosion are the region. It was also found other factors in the evolution of land use contrary to gully erosion region. That is because of the lack of culture in this area and dropping land by farmers as wasteland, and also because of the recent drought in the region has caused more and more extend of gully erosion and land with the ability crop damage and destroy all. The results obtained showed that the study area in terms of of gully erosion in critical condition.